One problem with microprocessor control of separately excited motors results from the fact that the fiel flux expected from a given field current, as derived from the motor equations employed, is not always as expected. Specifically, actual field flux will differ from a given value, primarily as a result of magnetic hysteresis in the field poles. This variation in fiel flux is also attributable to motor-to-motor variations arising from manufacturing tolerances. Thus, while theory may predict optimal motor performance under given torque and speed conditions, in reality, the resulting operation is often not what is expected or desired. Accordingly, there is a need for a motor control scheme for a separately excited DC motor that accounts for the difference between the expected fiel flux and the actual field flux to improve the operation of the motor.

Another problem associated with microprocessor control of battery-powered separately excited motors arises when the voltage of the battery power source decreases with use. As the voltage decreases, the armature current decreases and the performance of the motor suffers. Accordingly, there is a need for a motor control scheme for a separately excited DC motor that additionally accounts for the decrease in battery voltage and armature current.

SUMMARY OF THE INVENTION These needs are met by the present invention wherein a motor control system is provided including a microprocessor programmed to modify the field current of a

separately excited motor to account for any reduction in-battery voltage by increasing the armature current. The microprocessor is also programmed to generate an armature voltage reference signal and a field current setpoint, compare the armature voltage reference signal to a measured armature voltage signal, generate an armature voltage error signal based on the comparison, and generate a field current correction signal as a function of the armature voltage error signal.

In a preferred embodiment of a motor control scheme according to the present invention, the field current is de-boosted when battery voltage begins to fall in order to maintain desired motor performance. Field de-boost is a field current modification based on an error signal between an armature current lookup table value and a measured armature current when armature voltage is substantially equal to battery voltage. Improved control over motor torque within the commutation limit of the motor is achieved for battery conditions below 90% state of charge. The field de-boost calculation adjusts the field current lookup table value to increase actual armature current up to the setpoint value. Field de-boost is only active during motoring, armature current positive forward and reverse states.

In addition, according to the motor control scheme of the present invention, the microprocessor may be programmed to execute a field current control function wherein optimal field current and armature current setpoints are established in accordance with tabulated values selected for providing a required torque and speed.

A table of corresponding armature voltage values is also maintained. Flux losses in the motor are detected indirectly by measuring the motor's armature voltage.

Specifically, a reduction of back EMF acting on the armature indicates a flux decrease. A voltage sensor sends measured values of armature voltage to an armature voltage comparator for comparison with expected values thereof as read out from the above-mentioned table. The differences are used for adjusting the field current setpoint and thereby adjusting the flux.

More specifically, the controller of this invention compensates for flux losses by using a table of armature voltage values to determine an armature voltage reference point. An armature voltage sensor measures the actual average armature voltage

and sends the measured value back to a microprocessor. The microprocessor compares the measured armature voltage with the armature voltage reference point and multiplies the difference by a variable gain factor to obtain a correction term. The correction term then is added to the field current setpoint in order to adjust flux as required.

In another preferred embodiment of a motor control scheme according to the present invention, optimal field current and armature current setpoints are established in accordance with tabulated values selected for providing a required torque and speed. A table of corresponding armature voltage values is also maintained. Flux losses in the motor are detected indirectly by measuring the motor's armature voltage. Specifically, a reduction of back EMF acting on the armature indicates a flux decrease. A voltage sensor sends measured values of armature voltage to an armature voltage comparator for comparison with expected values thereof as read out from the above-mentioned table. The differences are used for adjusting the field current setpoint and thereby adjusting the flux.

More specifically, the controller of this invention compensates for flux losses by using a table of armature voltage values to determine an armature voltage reference point. An armature voltage sensor measures the actual average armature voltage and sends the measured value back to a microprocessor. The microprocessor compares the measured armature voltage with the armature voltage reference point and multiplies the difference by a variable gain factor to obtain a correction term. The correction term then is added to the field current setpoint in order to adjust flux as required.

The look-up tables of the present invention, described in further detail herein, output field and armature current values that are optimized to minimize component heating by minimizing armature current. The tables are generated based on empirical fit functions to dynamometer data on a limited sampling of a particular motor configuration. Since the tables are constructed based on a defined model, component tolerances, wear, heating, and state of battery charge can contribute to sample-to-sample variances in resultant output horsepower or energy conversion.

Further, since the tables are built using a nominal battery voltage at 90% state of charge, any level below this will not only lower armature voltage but will also lower armature current, resulting in a reduction in peak torques and a corresponding premature loss in vehicle acceleration. Peak torque reduction can be lessened by holding armature currents to their desired level.

In accordance with one embodiment of the present invention, a motor control system is provided comprising an electrically charged battery, an electrical motor, a battery voltage sensor, an armature voltage sensor, an armature current sensor, and a microprocessor. The electrical motor is coupled to the battery and includes an armature assembly responsive to an armature current and a field assembly responsive to a field current. The magnitude of the armature current is a function of a predetermined armature current setpoint signal la sET. The magnitude of the field current is a function of a predetermined field current setpoint signal If SET and a field current de-boost signal If DE-BOOST The battery voltage sensor is arranged to generate an operating battery voltage signal VBAT. The armature voltage sensor arranged to generate a measured armature voltage signal Va from the electrical potential of the armature assembly. The armature current sensor is arranged to generate a measured armature current signala indicative of an amount of current flowing through the armature assembly. The microprocessor is programmed to generate an armature current setpoint signal la sEr, a field current setpoint signal If SET, and an armature-to-field current check function. The check function defines a <BR> <BR> <BR> <BR> set of armature current to field current ratio values (la/If VCHECK as a function of armature current. The microprocessor is also programmed to calculate a ratio of the measured armature current signala to the field current setpoint signal If SET to <BR> <BR> <BR> establish an operating ratio value la/If SET and to compare the operating ratio value<BR> <BR> <BR> <BR> <BR> <BR> la/If SET to a corresponding armature current to field current ratio value

( CHECK of the armature-to-field current check function. Finally, the microprocessor is programmed to establish the field current de-boost signal If DE- Boosr'wherein the magnitude of the field current de-boost signal If_DE-BOOST is a function of the measured armature current signala and the comparison of the operating ratio value la//fSET to the corresponding ratio value (la/If) CHECK The microprocessor may be programmed to compare the operating ratio value la//fSETtO the corresponding armature current to field current ratio value (Ia/If) CHECK by determining whether the operating ratio value Ia/If_SET is greater than the corresponding ratio value (la /If)CHECK. The microprocessor may be programmed to establish the magnitude of the field current de-boost signal If DE- BoosT according to a selected one of two distinct de-boost equations. The identity of the selected equation depends upon the outcome of the comparison of the operating <BR> <BR> <BR> ratio value la/If SET to the corresponding armature current to field current ratio value<BR> <BR> <BR> <BR> <BR> ( CHECK Preferably, the two distinct de-boost equations are as follows : la If _SET= Ia/ /Iw CHECK If_SET = If_SET-[(Ia_ERROR)#If_GAIN] where I'f_SET represents a de-boosted field current setpoint signal, where If GAIN represents a preselected gain parameter, and wherein the microprocessor is further programmed to generate an armature current error signal la ERROR bY comparing the armature current setpoint signal la SET and the measured armature current signal la.

Preferably, the microprocessor is programmed to select the first equation when the

operating ratio value la//fSETS greater than the corresponding armature current to<BR> <BR> <BR> <BR> <BR> <BR> <BR> field current ratio value (la//f) CHECK and to select the second equation when the operating ratio value Ia/If_SET is not greater than the corresponding armature current to field current ratio value (Ia/If)CHECK.

The electrical motor is characterized by a set of commutation limits and the microprocessor is preferably programmed to generate the armature-to-field current check function such that the check function simulates the commutation limits as a function of armature current. Preferably, the armature-to-field current check function is defined by the following equations : \ I p If CHECK (Xf) MG (Xf) GHIN (Xf) (Xf) CHECK (Xf) MIN (Xf) GHIN equation (1) equation (2) where (Ia/If)MAX represents a maximum armature current to field current ratio within the commutation limits, (Ia/If)MIN represents a minimum armature current to field current ratio within the commutation limits, (Ia/If)GAIN represents the following product <BR> <BR> <BR> <BR> GDE-BOOST X (VREF-YBAT)<BR> <BR> <BR> <BR> <BR> <BR> <BR> where GDE-BOOSTS a predetermined gain parameter, VREF represents a reference<BR> <BR> <BR> <BR> <BR> <BR> battery voltage, e. g., 36 volts, and (la/If) SLOPE represents the following product<BR> <BR> <BR> <BR> <BR> Ia X MDE BOOST<BR> <BR> <BR> <BR> <BR> <BR> <BR> where m DE-BOOST is a predetermined slope parameter. The predetermined gain<BR> <BR> <BR> <BR> <BR> <BR> parameter GDE-BOOST represents an allowable increase in armature to field current ratio per battery volts. The predetermined slope parameter represents a maximum ratio of armature to field current per amp of armature current. The microprocessor

may be programmed to generate the armature to field current check function such that the check function is defined by equation (1) when (Y, f) CHE CK) [ (Yf) MIN + (Yf) GA IN] and by equation (2) when (Ia If1 CHECK \IQ If l MIN +'IQ IfJGAIN The microprocessor may further be programmed to : generate a full-on indication signal when the measured armature voltage signal Va is substantially equal to the operating battery voltage signal ABAT, generate an armature current error signal la ERROR bY comparing the armature current setpoint signal la SET and the measured armature current signala ; generate a low armature current indication signal when the armature current error signal la ERROR exceeds a predetermined value ; and enable the field current de-boost signal establishing step according to whether the full-on indication signal and the low armature current indication signal are generated. Preferably, the microprocessor is further programmed to generate the armature current error signal according to the following equation <BR> <BR> <BR> <BR> la_ ERROR = Ia-Ia-SET and to generate the full-on indication signal when<BR> <BR> <BR> <BR> <BR> <BR> <BR> <BR> <BR> Va > VBAT-IlBAT-TOLERANCE, where VBAT TOLERANCE S a predetermined voltage tolerance. Alternatively, the microprocessor is programmed to generate the low <BR> <BR> <BR> <BR> armature current indication when la < Ia_SET-Ia_TOLERANCE, where la TOLERANCES a predetermined current tolerance.

The field assembly may be further responsive to a field current correction signal If CORRECTION, the motor control system may further comprise a motor speed sensor arranged to generate an actual motor speed signal Ct) representative of an

actual speed of the electrical motor, and the microprocessor may be further programmed to : generate an armature voltage reference signal Va REF, compare the armature voltage reference signal Va REF to the measured armature voltage signal Va and generate an armature voltage error signal Va ERROR based on the comparison, and generate the field current correction siGnal If CORRECTION as a function of the armature voltage error signal.

In accordance with yet another embodiment of the present invention, a motor control system is provided comprising an electrically charged battery, an electrical motor, a battery voltage sensor, a motor speed sensor, an armature voltage sensor, an armature current sensor, and a microprocessor. The electrical motor is coupled to the battery and includes an armature assembly responsive to an armature current and a field assembly responsive to a field current. The magnitude of the armature <BR> <BR> <BR> <BR> current is a function of a predetermined armature current setpoint signal/a sET and the magnitude of the field current is a function of a predetermined field current <BR> <BR> <BR> <BR> setpoint signal/fSETX a field current correction siGnal/fCORRECTlONS and a field<BR> <BR> <BR> <BR> <BR> <BR> <BR> current de-boost signal/fDE-BOOST The microprocessor programmed to generate an armature current setpoint signal la SET, a field current setpoint signal If SET, and an armature voltage reference signal Va REF. Further, the microprocessor is programmed to (i) compare the armature voltage reference signal Va REF to the measured armature voltage signal Va and generate an armature voltage error signal Va ERROR based on the comparison ; (ii) generate the field current correction signal If CORRECTiON as a function of the armature voltage error signal ; (iii) generate an armature-to-field current check function, wherein the check function defines a set of <BR> <BR> <BR> <BR> armature current to field current ratio values (la//f) CHECK as a function of armature current ; (iv) calculate a ratio of the measured armature current signala to the field

current setpoint signal If SET to establish an operating ratio value la//fSET (V) compare the operating ratio value Ia/If_SET to a corresponding armature current to <BR> <BR> <BR> <BR> field current ratio value (la//f) CHECK °f the armature-to-field current check<BR> <BR> <BR> <BR> <BR> <BR> <BR> function, and (vi) establish the field current de-boost signal/fDE-BOOSTs wherein the magnitude of the field current de-boost signal If_DE-BOOST is a function of the measured armature current signala and the comparison of the operating ratio value /a/If SET to the corresponding ratio value (la//f) CHECK- The microprocessor may further be programmed to generate the field current correction signal/fCORRECT/ON such that it is inversely proportional to the actual motor speed signal #, to generate the field current correction signal If CORRECTION as a function of the armature voltage error signal Va ERROR and the actual motor speed signal Ct), or to generate the field current correction signal If CORRECTION according to the following equation : If _ CORRECUON = Va LIUtOR X Cl X (gt) where Va ERRORS the armature voltage error signal, C1 is a constant, Guis a variable gain parameter, and # is the actual speed of the motor. The microprocessor may be further programmed to modify the measured armature voltage signal Va by summing the measured armature voltage signal Va and the operating battery voltage signal VBAT prior to comparing the measured armature voltage signal Va to the armature voltage reference signal Va REF.

The motor control system may further comprise a speed command generator arranged to generate a speed command signal S indicative of a desired speed of the electrical motor and the microprocessor may be further programmed to generate the

armature voltage reference signal Va REF, the field current setpoint/fSET and the<BR> <BR> <BR> <BR> <BR> <BR> armature current setpoint la SET as a function of the speed command signal S and the actual motor speed signal Ct). The microprocessor may additionally be programmed to generate the armature voltage reference signal Va REF, the field <BR> <BR> <BR> <BR> current setpoint If SET, and the armature current setpoint la SET from a look-up table having at least one input value derived from the speed command signal S and the actual motor speed signal CO. The look-up table may be a dual-input look-up table, <BR> <BR> <BR> <BR> wherein a first input of the look-up table comprises a torque setpoint signal TSET and wherein a second input of the look-up table comprises the actual motor speed signal <BR> <BR> <BR> <BR> cet7. The microprocessor may be programmed to generate the torque setpoint signal TSET as a function of the actual motor speed signal d) and the speed command signal S.

In accordance with yet another embodiment of the present invention, a motor control system is provided comprising an electrical motor, a motor speed sensor, a speed command generator, an armature voltage sensor, and a microprocessor. The electrical motor includes an armature assembly and a field assembly. The armature assembly is responsive to an armature current, the magnitude of which is a function of a predetermined armature current setpoint. The field assembly is responsive to a field current, the magnitude of which is a function of a predetermined field current setpoint and a field current correction signal. The motor speed sensor is arranged to generate an actual motor speed signal representative of an actual speed of the electrical motor. The speed command generator is arranged to generate a speed command signal indicative of a desired speed of the electrical motor. The armature voltage sensor is arranged to generate a measured armature voltage signal from an electrical potential of the armature assembly. The microprocessor is programmed to : (i) generate an armature voltage reference signal, the field current setpoint, and the armature current setpoint, wherein the armature voltage reference signal, the field

current setpoint, and the armature current setpoint as a function of the speed command signal and the actual motor speed signal ; (ii) compare the armature voltage reference signal to the measured armature voltage signal and generate an armature voltage error signal based on the comparison ; and, (iii) generate the field current correction signal as a function of the armature voltage error signal.

The microprocessor may further be programmed to generate the field current correction signal such that it is inversely proportional to the actual motor speed signal.

The microprocessor may also be programmed to generate the field current correction signal as a function of the armature voltage error signal and the actual motor speed signal. Further, the microprocessor may be programmed to generate the field current correction signal in response to the armature voltage error signal and the actual motor <BR> <BR> <BR> <BR> speed signal or to generate the field current correction signal 7/corn. c according to the following equation : If c7yo, v = Va ERRORX CIX (GI _ where Va-ERRoR is the armature voltage error signal, C1 is a constant, Guis a variable gain parameter, and d) is the actual speed of the motor. The constant C1 preferably includes a motor constant K, unit scaling corrections, and a coefficient for , where If SETS the field current setpoint and B represents the magnetic flux in the air gap of the electrical motor.

Where the armature assembly includes high and low voltage nodes, the armature voltage sensor is preferably arranged to measure armature voltage at the low voltage node. Where the electrical motor is driven by a battery voltage characterized by a battery voltage signal, the microprocessor may be programmed to modify the measured armature voltage signal by summing the measured armature voltage signal and the battery voltage signal prior to comparing the measured armature voltage signal to the armature voltage reference signal.

The microprocessor may be programmed to generate the armature voltage

reference signal, the field current setpoint, and the armature current setpoint from a look-up table. According to one embodiment of the present invention, the look-up table is a dual-input look-up table, wherein a first input of the look-up table comprises a torque setpoint signal, and wherein a second input of the look-up table comprises the actual motor speed signal. The microprocessor may be programmed to generate the torque setpoint signal as a function of the speed command signal and the actual motor speed signal. Additionally, the microprocessor may be programmed to generate the armature voltage reference signal, the field current setpoint, and the armature current setpoint from a look-up table having at least one input value derived from the speed command signal and the actual motor speed signal.

In accordance with yet another embodiment of the present invention, a motor control circuit is provided comprising a motor speed sensor, a speed command generator, an armature voltage sensor, and a microprocessor programmed to : (i) generate an armature voltage reference signal, a field current setpoint, and an armature current setpoint, wherein the armature voltage reference signal, the field current setpoint, and the armature current setpoint are generated as a function of the speed command signal and the actual motor speed signal ; (ii) compare the armature voltage reference signal to the measured armature voltage signal and generate an armature voltage error signal based on the comparison ; and, (iii) generate a field current correction signal as a function of the armature voltage error signal.

In accordance with yet another embodiment of the present invention, a motor control system is provided comprising an electrical motor, a motor speed sensor, an armature voltage sensor, and a microprocessor programmed to : (i) generate an armature voltage reference signal and the field current setpoint ; (ii) compare the armature voltage reference signal to the measured armature voltage signal and generate an armature voltage error signal based on the comparison ; and, (iii) generate the field current correction signal as a function of the armature voltage error signal.

In accordance with yet another embodiment of the present invention, a motor control circuit is provided comprising a motor speed sensor, an armature voltage

sensor, and a microprocessor programmed to : (i) generate an armature voltage reference signal and a field current setpoint ; (ii) compare the armature voltage reference signal to the measured armature voltage signal and generate an armature voltage error signal based on the comparison ; and (iii) generate a field current correction signal as a function of the armature voltage error signal.

In accordance with yet another embodiment of the present invention, a motor control system is provided comprising an electrical motor, a motor speed sensor, a speed command generator, an armature voltage sensor, and a microprocessor. The electrical motor is driven by a battery voltage characterized by a battery voltage signal, and includes an armature assembly including high and low voltage nodes and a field assembly. The armature assembly is responsive to an armature current, wherein a magnitude of the armature current is a function of a predetermined armature current setpoint. The field assembly is responsive to a field current, wherein a magnitude of the field current is a function of a predetermined field current setpoint and a field current correction signal. The motor speed sensor is arranged to generate an actual motor speed signal representative of an actual speed of the electrical motor. The speed command generator is arranged to generate a speed command signal indicative of a desired speed of the electrical motor. The armature voltage sensor is arranged to generate a measured armature voltage signal from an electrical potential of the armature assembly at the low voltage node. The microprocessor is programmed to : (i) generate an armature voltage reference signal, the field current setpoint, and the armature current setpoint from a dual-input look-up table, wherein a first input of the look-up table comprises a torque setpoint signal, wherein a second input of the look-up table comprises the actual motor speed signal, and wherein the microprocessor is programmed to generate the torque setpoint signal as a function of the speed command signal and the actual motor speed signal ; (ii) compare the armature voltage reference signal to the measured armature voltage signal and generate an armature voltage error signal based on the comparison ; (ii) modify the measured armature voltage signal by summing the measured armature voltage signal and the battery voltage signal prior to comparing the measured armature voltage signal to the armature voltage reference signal ; and, (iii)-generate the field current correction signal If correction according to the following equation : if-coRREc27oN = Va ERROR Xcl X (GI Accordingly, it is an object of the present invention to provide a motor control scheme for a separately excited DC motor that accounts for the difference between the expected field flux and the actual fiel flux to expand the power envelope of the motor. Further, it is an object of the present invention to provide a motor control scheme for a separately excited DC motor that accounts for the difference between the expected fiel flux and the actual field flux to improve the operating efficiency of the motor. Other objects of the present invention will be apparent in light of the description of the invention embodied herein.

BRIEF DESCRIPTION OF THE DRAWINGS The following detailed description of the present invention can be best understood when read in conjunction with the following drawings, where like structure is indicated with like reference numerals and in which : Fig. 1 is a schematic block diagram illustrating a motor control system of the present invention ; Figs. 2 and 3 are complementary portions of a detailed schematic block diagram illustrating a motor control system of the present invention ; Fig. 4 illustrates the manner in which Figs. 2 and 3 are combined to form a complete detailed schematic block diagram of the motor control system of the present invention ; Fig. 5 is a flow chart illustrating the process by which voltage and current values are determined and stored in look-up tables according to the present invention ; Fig. 6 is a graph illustrating a pair of commutation limit plots for a separately excited DC motor ; Figs. 7A-C are flow chart illustrating alternate field current modification

schemes of the present invention ; Fig. 8 is a flow chart illustrating a field current compensation scheme of the present invention ; Fig. 9 is a flow chart illustrating a field current de-boost scheme of the present invention ; Fig. 10 is a graph illustrating the manner in which an armature-to-field current check function is generated according to the present invention ; Fig. 11 is a graph illustrating the behavior of motor speed (left y-axis) and torque (right y-axis) as a function of acceleration time, without field current de-boost ; Fig. 12 is a graph illustrating the behavior of armature current as a function of acceleration time, without field current de-boost ; Fig. 13 is a graph illustrating the behavior of field current as a function of acceleration time, without field current de-boost ; Fig. 14 is a graph illustrating the behavior of armature voltage as a function of acceleration time, without field current de-boost ; Fig. 15 is a graph illustrating the behavior of motor speed (left y-axis) and torque (right y-axis) as a function of acceleration time, with field current de-boost ; Fig. 16 is a graph illustrating the behavior of armature current as a function of acceleration time, with field current de-boost ; Fig. 17 is a graph illustrating the behavior of field current as a function of acceleration time, with field current de-boost ; and Fig. 18 is a graph illustrating the behavior of armature voltage as a function of acceleration time, with field current de-boost.

DETAILED DESCRIPTION OF THE INVENTION Referring now to Figs. 1-4, a motor control system 100 according to the present invention is illustrated in detail. The motor control system 100 comprises an electrical motor 10 including an armature assembly 12 and a field assembly 14, a speed command generator 16, an armature voltage sensor (see line 45), a microprocessor 15, and a motor control circuit 20. A speed sensor 25, e. g., an

encoder or tachometer, provides an output on a line 30-representing the actual speed cl) (rad/sec) of the motor 10.

Shown within the microprocessor 15 are several blocks that represent functions performed by the microprocessor 15 and the associated hardware. The blocks or routines of particular interest include a speed comparator function 50, a set of two-way look up tables 60, an armature voltage error function 70, an armature current error function 73, and a field current modification function 75.

Setpoint Determination.

The speed comparator function 50 compares a speed command signal on a line 35 to the actual motor speed signal on the line 30 and, in response thereto, provides a torque command signal on a line 55 to the look up tables 60. Specifically, referring to Figs. 2 and 3, which figures represent respective portions of the entire motor control system 100 and which figures are interconnected to one another as shown in Fig. 4, the speed command signal S on the line 35 and the actual speed signal Gl) on the line 30 are applied to the speed comparator function 50 in the microprocessor 15. More specifically, the signals S and Ware inputs to a comparator 51, the output of which is applied to an amplifier function or amplifier 52 which has a gain Kp set to command a torque high enough for rapid response to a speed error but low enough to avoid stability problems. Thus, the output of amplifier 52 is Tp = Kp (s- Proportional plus integral control (PIC) is achieved by integrating the speed error and adding the result to the output of the amplifier 52. This is done by an amplifier function or amplifier 53, which integrates the output of the comparator 51. <BR> <BR> <BR> <BR> <P>Thus, its output is Ti = Kif (s-w) dt. The outputs of the amplifiers 52 and 53 are added by function 54, giving the torque setpoint signal T = Ti + Tp on the line 55. The gain of Kp of the amplifier function 52 and the gain Ki of the amplifier function or amplifier 53 are conditionally proportional to the motor speed signal on the line 30. At low motor speed, the gain is higher than at higher speeds. This provides stability and the

necessary torque for hill holding. The amplifier 52 provides the initial response to a new speed command. The response from the integrator amplifier 53 builds up slowly and predominates as the speed error is driven to zero. The steady state output from the integrator amplifier 53 produces torque setpoint values appropriate for handling a steady state load with no error signal from the speed comparator 51.

Referring now to the look up tables 60, table 62 contains a matrix of expected armature voltage values Va, table 64 contains a matrix of field current values If, and table 66 contains a matrix of armature current values Field current and armature current setpoints are produced by the look-up tables 64 and 66, based upon the actual speed signal 0) and the torque command or torque setpoint signal on the line 55, and are applied to the motor control circuit 20. The field current setpoint is modified by the field current modification function 75, as will be explained in detail below.

It is contemplated by the present invention that, although the embodiment described herein, where the torque setpoint signal and the actual speed signal S are used as inputs to a look up table to determine the field current and armature current setpoints and the expected armature voltage values, others schemes may be employed to determine the setpoints and expected values without departing from the scope of the present invention. This is particularly the case for embodiments of the present invention where the determination of these values is not the critical aspect of the particular embodiment.

Field Current Modification.

Referring to Figs. 7A to 7C, three schemes for executing field current modification according to the present invention are illustrated. Generally, the field current modification function 75 includes two distinct components : field current compensation (also identifiable as field current boost) and field current de-boost. The field current compensation component is described in detail herein with reference to Figs. 1-3 and 8. The field current de-boost component is described in detail herein

with reference to Figs. 1-3 and 9-18.

The first scheme for achieving field current compensation and field current de- boost is illustrated in Fig 7A, wherein the field modification routine 200 first determines whether field compensation is needed, see step 202. If fiel compensation is needed, it is executed, see step 204, if not, the routine 200 determines whether field de-boost is needed, see step 206. If fiel de-boost is needed, it is executed, see step 208, if not, the routine returns to step 202. The field modification routine 200'of Fig. 7B is slightly different that the routine 200'.

Specifically, the field modification routine 200'first determines whether field compensation is needed, see step 210. If field compensation is needed, it is executed, see step 212, and the routine returns to step 210 without even attempting to determine if de-boost is needed. If, and only if, field compensation is not needed, does the routine 200'attempt to determine whether field de-boost is needed, see step 214. If field de-boost is needed, it is executed, see step 216, if not, the routine returns directly to step 210. The field compensation routine 200"of Fig. 7C is similar to the one illustrated in Fig. 7B. Specifically, the field modification routine 200"first determines whether field de-boost is needed, see step 218. If field de-boost is needed, it is executed, see step 220, and the routine returns to step 218 without even attempting to determine if field compensation is needed. If, and only if, field de-boost is not needed, does the routine 200"attempt to determine whether field compensation is needed, see step 222. If field compensation is needed, it is executed, see step 224. If not, the routine returns directly to step 218. In the field compensation routine 200'of Fig. 7B, field compensation may be identified as the primary modification scheme, while, in the field compensation routine 200"of Fig. 7C, field de-boost may be identified as the primary modification scheme. Selection of an appropriate modification scheme 200, 200', 200"is dependent upon the specific programming preferences of those practicing the present invention. The alternative routines are merely presented herein to provide a clear description of the present invention. The specific steps involved with executing field current compensation and field current de-boost are described in detail below with reference to Figs. 8-10.

Field Current Compensation.

Referring now to Figs. 1-3, a voltage signal on the line 45 from the armature assembly 12, from which flux level is derived, is fed back to the armature voltage error function 70 of the microprocessor 15. The field current modification function 75 adjusts the field current setpoint in accordance with the signal output from the armature voltage error function 70. Specifically, if the armature voltage on the line 45 is not what is expected, based on the torque command signal on the line 55 and the actual speed of the motor represented on the line 30, then the field current signal on a line 42 is adjusted accordingly. The reason armature voltage will not be as expected is due primarily to hysteresis in the flux characteristics in the motor field poles, and also to motor-to-motor manufacturing tolerances. The armature voltage values Va in table 62 are calculated based on the expected flux. The expected flux is determined as a function of the nominal flux characteristics of the particular motor.

The actual flux of the motor will be somewhat different from the expected flux, due primarily to hysteresis. The motor control scheme of the present invention accounts for this difference in flux by adjusting the field current.

The armature voltage error function 70 includes a comparator function 72 that receives a signal representing battery voltage on a line 71 and a signal representing the voltage Va1 from the low voltage side of the armature bridge on the line 45. Both lines 45 and 71 include analog to digital, or A-D, converter circuits, 92 and 93, see Fig. 3. The output Vg'ofthe comparator function 72 is compared with the output Va REFERENCE from the look-up table 62. If the voltage output signal Va of the comparator 72 is less than what is called for by the look-up table 62, then an output <BR> <BR> <BR> <BR> signal VA-ERRER is generated and applied to an amplifier 74. The amplifier 74 also receives the motor speed signal Cc). The output of the amplifier 74 is added to the If <BR> <BR> <BR> <BR> setpoint signal on a line 41 in adder function 76 to produce an adjusted or modified/f setpoint on a line 42.

Regarding the operation of the amplifier 74, it is initially noted that the back EMF E of a motor is defined as E=KxBxw where K is a motor design constant, B is the magnetic flux in the air gap of the motor (the gap between the poles of the field assembly 14 and the core of the armature assembly 12), and # is the rotational speed of the armature assembly 12.

Differentiating the equation with respect to If yields Rearranging the equation for dlfyields In practice, this equation is implemented in a field adjustment gain term Gv in the following form : if-coRREcyyoA, = Va-ERRoi ? X Cl X W) where Va ERRORS the armature voltage error signal A (see Fig. 2), Ci is a constant, <BR> <BR> <BR> Gv is a variable gain parameter, and co is the actual speed of the motor, and where the magnitude of the field current correction signal is inversely proportional to the actual motor speed signal Gl). The constant Cl includes the motor constant K, unit scaling corrections, and a coefficient for where If is the field current setpoint and B represents the magnetic flux in the air gap of the electrical motor. The motor constant K is computed as follows <BR> <BR> (NC)(NP)<BR> K =<BR> 2#(NA)

where Nc is the number of conductors in the armature assembly 12, Np is the number of poles in the armature assembly 12, and NA is the number of parallel armature current paths in the armature assembly 12. The value for Gv, the variable gain parameter, is selected to tune the amplifier 74 for optimum performance. It is noted that, although typical values for Gv range from about 100 to about 500, the specific value for Gv is subject to determination for each individual motor to be controlled by the motor control scheme of the present invention.

It is contemplated by the present invention that, in certain embodiments or applications of the present motor control scheme, it may be preferable to establish a <BR> <BR> <BR> <BR> <BR> threshold motor speed CUBOOST below which the armature voltage error function will be inactivated. Further, it is contemplated by the present invention that, in certain embodiments or applications of the present motor control scheme, it may be preferable to establish a maximum armature voltage setpoint threshold slightly below the actual value of the battery voltage, e. g., about 0. 03 volts below the actual value of the battery voltage. Finally, it is contemplated by the present invention that, in certain embodiments or applications of the present motor control scheme, the field current will be adjusted only where : (i) the actual motor speed is greater than a minimum speed threshold corresponding to the adjusted field current setpoint ; and (ii) the actual armature voltage is less than the armature voltage setpoint. Preferably, there are no limitations placed on the degree to which the field current may be increased by the armature voltage error function 70, with the exception, of course, that the field current and the armature voltage setpoint cannot exceed the physical limitations of the battery power source. Specifically, the maximum field current cannot be greater than the battery voltage divided by the field resistance and the armature voltage setpoint cannot be greater than the battery voltage.

Referring now to Fig. 8, certain aspects of a field current compensation routine 300 according to the present invention are illustrated in detail. The routine 300 includes three distinct queries. According to a first query, the routine 300 establishes a maximum value for the armature voltage setpoint when the armature voltage

setpoint is close to, or greater than, the actual value of the battery voltage, see steps 302, 304. According to a second query, the routine 300 determines whether the actual motor speed l. is greater than the predetermined threshold motor speed <BR> <BR> <BR> <BR> <BR> <BR> WBOOST and generates a command to disable field current compensation if the actual<BR> <BR> <BR> <BR> <BR> <BR> <BR> <BR> <BR> motor speed W is not greater than the threshold motor speed Boosr'see steps 306, 310. A final query determines whether the actual armature voltage is less than the armature voltage setpoint, see step 308. If the actual armature voltage is less than the armature voltage setpoint, the field current is corrected according to the above-described algorithm, see step 312. If the actual armature voltage not less than the armature voltage setpoint, a command to disable field current compensation is generated, see step 310.

Field De-Boost.

Referring now to Figs. 1-3, 9, and 10, the field current de-boost component 400 of the field current modification routine of the present invention is described in detail. The armature assembly 12 of the motor 10 is responsive to an armature current, the magnitude of which is a function of a predetermined armature current setpoint signal la SET (see Fig. 2, line 40). Similarly, the field assembly 14 is responsive to a field current, the magnitude of which is a function of a predetermined field current setpoint signal If SET (see line 41) and a field current de-boost signal If DE-BOOST (see line 43). The microprocessor 15 is programmed to generate the armature current setpoint signal la SET and the field current setpoint signal If SET, in the manner described in detail herein. Further, the microprocessor 15 is programmed to generate the field current de-boost signal If DE-BOOST to accomplish suitable modification of the field current according to the present invention.

Generally, referring to the field current de-boost routine 400 illustrated in Fig. 9, as will be described in greater detail in the following paragraphs, the field current de-

boost siGnal/fDE-BOOSTiS generated after performing a set of predetermined threshold queries, see steps 402, 404, and 406. First, an armature-to-field current check function is generated that defines a set of armature current to field current ratio values (la//f) CHECK as a function of armature current, see steps 408, 410, and 412. An operating ratio value Ia/If_SET is established and compared to a corresponding armature current to field current ratio value (la//f) CHECK °f the armature-to-field current check function, see step 414. The operating ratio value <BR> <BR> <BR> <BR> la//fSETiS calculated as a ratio of the measured armature current signala to the<BR> <BR> <BR> <BR> <BR> <BR> <BR> <BR> field current setpoint signal/fSET The result of the comparison of the operating ratio<BR> <BR> <BR> <BR> <BR> <BR> <BR> <BR> <BR> value la/If SET and the field current ratio value (la//f) CHECKiS used to establish the field current de-boost signal If_DE-BOOST, see steps 416 and 418. The magnitude of the field current de-boost signal If_DE_BOOST is a function of the measured armature current signala input from line 36 (see Figs. 2 and 3) and the comparison of the operating ratio value la//fSET to the corresponding ratio value ! CHECK The first threshold query is designed to generate a"no de-boost"condition unless the motor 10 is being operated in a"full-on"condition, see steps 402 and 406.

Specifically, a full-on indication signal is generated when the measured armature <BR> <BR> <BR> <BR> voltage signal Va is substantially equal to the operating battery voltage signal VBAT, for example, when Va > VBAT - VBAT_TOLERANCE, wher eVBAT_TOLERANCE is a predetermined voltage tolerance. The armature voltage signal Va may be measured directly from the armature or measured indirectly through measurements of the output <BR> <BR> <BR> <BR> Va'of the comparator function 72 on line 69 and the battery voltage signal VBAT on line 71. The field current de-boost signal If DE-BOOST is not generated under the"no de-boost"condition.

The second threshold query is designed to generate a"no de-boost"condition if the armature current is not below a predetermined armature current value, see steps 404 and 406. Specifically, an armature current error signal la ERROR iS generated by comparing the armature current setpoint signal la SET and the measured armature current signal A low armature current indication signal is generated when the armature current error signal/a ERROR indicates that the measured armature current signal la is below the predetermined armature current value. The microprocessor 15 is programmed to generate the armature current error <BR> <BR> <BR> <BR> <BR> signal according to the following equation : Ia_ FRnoR = la-Ia_ SET. The generation of the low armature current indication signal is conditioned upon whether the armature <BR> <BR> <BR> <BR> <BR> current error signal/a_ERROR exceeds a predetermined current tolerance value<BR> <BR> <BR> <BR> <BR> <BR> <BR> <BR> <BR> <BR> /a_TOLERANCE The armature-to-field current check function is generated so as to simulate the commutation limits of the electrical motor 10 being controlled. Specifically, referring to Figs. 6 and 10, the commutation limits of the electrical motor 10 are illustrated. In Fig. 6, the commutation limits of the field and armature currents are plotted for a motor operating at 24 volts and a motor operating at 36 volts. As the graph illustrates, the number of specific armature and field current combinations for operation below the commutation limits of the motor increases as the operating voltage decreases. In Fig. 10, the commutation limit ratio (la/If) is plotted as a function of armature current, for each operating voltage, to help illustrate the manner in which the check function is determined. Specifically, the check function is generated so as to simulate the commutation limits ratio as a function of armature current for the electrical motor 10 operating at 36 volts. As is described in detail herein appropriately selected gain parameters are utilized to correct the function for operating voltages other than 36 volts.

Referring specifically to Fig. 10, a check function according to the present invention is illustrated as the combination of two distinct sub-functions or lines C1 and C2. The lines C1, C2 are defined so as to represent a close fit approximation of the actual commutation limit ratio plotted as a function of armature current. Specifically, the armature-to-field current check function is defined by the following equations : (llf) CHECK \I a If MAX + I IQ If JGAIN \I p If l SLOPE (Yif) CHECK (7/f) MIN (S/f) GSIN equation (1) equation (2) (/,/If) represents the maximum armature current to field current ratio within<BR> <BR> <BR> <BR> <BR> <BR> <BR> <BR> <BR> the commutation limits, approximately 72 in the Fig. 10 example. (la//f) MIN represents the minimum armature current to field current ratio within the commutation limits, approximately 20 in the Fig. 10 example. la/If) GAIN represents the following product <BR> <BR> <BR> <BR> <BR> GDE-BOOST X (VREF-VBAT),<BR> <BR> <BR> <BR> <BR> <BR> <BR> <BR> <BR> where Gdeboostis a predetermined gain parameter, approximately 1. 7 in the Fig. 10<BR> <BR> <BR> <BR> <BR> <BR> <BR> <BR> <BR> example, and VREF represents a reference battery voltage of the commutation limit plot to which the sub-functions or lines are fit, 36 volts in the illustrated example.

(Ia/If)Slope represents the following product Ia X mDE_ BOOST where mDE-BOOST is a predetermined slope parameter representing the slope of the line C1 in Fig. 10. The predetermined gain parameter GDE-BOOST represents the allowable increase in armature to field current ratio per battery volts. The predetermined slope parameter m DE-BOOST corresponds to a maximum ratio of armature to field current per amp of armature current.

The check function is defined by equation (1) when (Xf) CHECK vLt xf) MIN (Wf) GAIN I and by equation (2) when (p/f) CHECK (F/f) MIN (2/f) GAIN H in order to ensure the check function closely approximates the actual armature current to field current ratio as a function of the armature current.

Referring now to step 414 of Fig. 9, once the check function has been defined, If) CHECK must be compared with the operating ratio value la/If SET to determine the value of the de-boosted field current setpoint signal. Specifically, the microprocessor 15 is programmed to determine whether the operating ratio value /a/If greater than the corresponding ratio value (la//f) CHECK The outcome of this comparison determines the manner in which the de-boosted field current setpoint signal is calculated. The microprocessor 15 is programmed to <BR> <BR> <BR> <BR> <BR> establish the magnitude of the field current de-boost signal/fDE-BOOST according to a selected one of two distinct de-boost equations, see steps 416 and 418. The identity of the selected equation depends upon the outcome of the comparison of the <BR> <BR> <BR> <BR> <BR> operating ratio value la//fSETtO the corresponding armature current to field current<BR> <BR> <BR> <BR> <BR> <BR> <BR> <BR> <BR> ratio value (la//f) CHECK The two distinct de-boost equations are as follows : Ia If _ SET = (IXI) \ f l CHECK equation (3) If SET = If_SET-[(Ia_ERROR)#If_GAIN] equation (4)

where//gr represents the de-boosted field current setpoint signal on line 42 and where If GAIN represents a preselected gain parameter that is selected to optimize performance of the motor control scheme. Typically, If_GAIN will range from about 0. 1 to about 1. 0. The microprocessor is programmed to generate the armature current error signal la ERROR bY comparing the armature current setpoint signal la SET and the measured armature current signal The microprocessor 15 is programmed to select equation (3) when the <BR> <BR> <BR> <BR> operating ratio value la//fSETiS greater than the corresponding armature current to<BR> <BR> <BR> <BR> <BR> <BR> field current ratio value (la//f) CHECKs see steps 414 and 416, and to select equation (4) when the operating ratio value la/If SET is not greater than the corresponding armature current to field current ratio value (Ia/If)CHECK, see steps <BR> <BR> <BR> <BR> 414 and 418. In this manner, if la/If SET is greater than la If) CHECK, the<BR> <BR> <BR> <BR> <BR> <BR> magnitude of I'f_SET is tied directly to (la//f) CHECK On the other hand if la/fSET<BR> <BR> <BR> <BR> <BR> <BR> <BR> is not greater than (la//f) CHECK. the magnitude of I'f_SET, then I'f-SET is proportional to the armature current error signal la ERROR Figs. 11-18 illustrate the effectiveness of the above-described field de-boost control scheme. Specifically, Figs. 11-14 illustrate speed, torque, armature current, field current, armature voltage, and battery voltage values, over time, as a motor is subject to acceleration without field current de-boost control according to the present invention. Referring to Fig. 11, note that actual speed 500 is significantly lower that the set speed 505 and that actual torque 510 is significantly lower than the set torque 515. Similarly, referring to Fig. 12, note that actual armature current 520 is significantly lower than the armature current set point 525. The field current set point 535 and actual field current 530 are illustrated in Fig. 13. The battery voltage 545, armature voltage 540, and armature voltage setpoint 550 are illustrated in Fig. 14.

In contrast, the values illustrated in Figs. 15-18 correspond to acceleration executed under the field current de-boost control according to the present invention.

Referring initially to Fig. 15, with de-boost control, the actual speed 600 comes much closer to the set speed 605 and reaches a higher maximum value than the actual speed 500 in Fig. 11. Similarly, the actual torque 610 is very close to the set torque 615. Fig. 16 illustrates the close correspondence of the actual armature current 620 and the armature current setpoint 625, particularly when compared with Fig. 12. Fig.

17 illustrates the fact that the actual field current 630 is less than the look-up table field current setpoint 635. Fig. 18 illustrates the fact that battery voltage 645, the actual armature voltage 640, and the armature voltage setpoint 650 each closely correspond to each other.

Look-up Table Construction.

Referring now to Fig. 5, the process by which the values stored in the look-up tables 60 are determined is described in detail. It is contemplated by the present invention, however, that a number of different schemes could be employed to determine preferred values for armature current, field current, and armature voltage setpoints, including schemes that do not utilize any look-up tables. Fig. 5 represents a routine 110 for minimizing armature current. The first step, see block 111, is to specify model parameter files for the desired motor configuration. The second step, see block 112, is to specify battery power constraints, minimum and maximum speed, minimum and maximum torque and look-up table size. The next step, see block 113 is to specify controller hardware current limits and commutation limits. Next, see block 114, limits on field current range based on power envelope and motor parameters are determined. In block 115, iman, imin to iman. Jmax are determined and represent a range of speed and torque setpoints. In block 117, the field excitation current which results in minimum armature current within a given range is determined.

The tables are generated based on empirical fit functions to dynamometer data on a limited sampling of a particular motor configuration. Since the tables are constructed based on a defined model, component tolerances, wear, heating, and state of battery

charge can contribute to sample-to-sampie variances in resultant output horsepower or energy conversion. Commutation voltage is calculated in block 118 and this data is put into matrices, see block 119. The process is then repeated, see block 120 for each element (i, j) in the tables. Finally, the tables are compile, see block 130, and stored. Thus, the following items are calculated and stored : armature current igrm (i, j) ; field current Ifld (i, j) ; armature voltage Va (i, j) ; calculated torque (i, j) ; motor efficiency (i, j) ; and, commutation voltage (i, j).

Table 1 is an example of a look-up table giving the desired armature current la for various values of torque T setpoints (left vertical column) and actual speed (top row). Similarly, Table 2 is an example of a look-up table for desired field current 1, at specified torques and speeds. Table 3 is an example of a look-up table that provides expected armature voltages Va at those specified torques and speeds. Table 4 represents expected torque. The torque value T in newton-meters (Nm) is provided by the speed comparator function 50 of the microprocessor 15 and the actual speed value is provided by the encoder 25. Speed is given in radians/second. In the preferred embodiment of this invention, the torque values in each table are in 5 newton-meter increments and the speed ranges from 0 to 400 radians/second. The data in these specific tables are unique to a given motor configuration or design since they are generated with reference to such factors that include but are not limited to the size, torque, and speed of the motor and internal motor losses. Interpolation may be used to determine values of If, la and Va for intermediate speed and torque values.

It is important to note that, although the following look-up tables are presented in substantial detail, the information embodied therein could be gleaned, through interpolation and routine experimentation, from a significantly abbreviated reproduction of the tables.

Table 1 - IARM T# ## 0 16 32 48 64 80 96 112 128 144 160 80 560 560 560 560 560 560 560 560 560 560 560 75 560 560 560 560 560 560 560 560 560 560 560 70 530 533 537 540 542 543 544 545 546 547 549 65 493 496 500 503 504 505 507 508 509 510 511 60 456 459 462 466 467 468 469 470 471 473 474 55 418 422 425 428 430 431 432 433 434 435 436 50 381 384 388 391 393 394 395 396 397 398 399 45 344 347 350 354 355 356 357 359 360 361 362 40 307 310 313 317 318 319 320 321 322 323 323 35 269 273 276 279 281 282 283 284 285 286 287 30 232 235 239 242 243 245 246 247 248 249 250 25 195 198 201 205 206 207 208 209 211 212 213 20 158 161 164 167 169 170 171 172 173 174 175 15 120 123 127 130 132 133 134 135 136 137 138 10 83 86 89 93 94 95 96 98 99 100 101 5 46 49 52 56 57 58 59 60 61 62 64 0 8 12 15 19 20 21 22 23 24 25 26 Table 1 (Cont.) T# ## 208 224 240 256 272 288 304 320 336 352 368 40 392 362 344 331 323 317 312 306 299 293 37.5 341 344 331 323 317 312 306 299 293 35 392 313 341 331 323 317 312 306 299 293 32.5 287 309 331 323 317 312 306 2899 293 30 292 262 281 303 323 317 312 306 299293 27.5 239 256 273 293 314 312 306 299 293 25 392 217 232 245 262 280 299 306 299 293 22.5 198 207 219 233 248 263 280 297 293 20 339 180 186 1894 206 218 231 244 258 273 287 17.5 161 164 171 180 190 200 211 223 235 247 15 253 142 143 149 156 163 171 190 189 1899 209 12.5 124 125 128 133 138 144 151 158 166 173 10 179 105 106 108 111 115 119 124 129 134 140 7.5 9687 89 91 92 96 98 10 106 19 5 104 67 68 69 70 71 72 74 78 78 90 2.5 47 48 49 49 49 50 50 51 62 53 0 30 31 32 33 34 35 36 37 38 39 40 Table 1 (Cont.) T# ## 0 16 32 48 64 80 96 112 128 144 160 - 5 56 48 45 - 44 - 44 - 45 - 46 - 47 - 48 - 49 - 50 -10 97 87 85 -80 -81 - 81 -82 - 83 - 84 - 85 - 86 -15 136 126 124 -117 -116 -116-117 -117 -118 -118 -119 -20 174 164 162 -151 -151 -151 -150 -149 -149 -152 -152 -25 210 200 198 195 -179 -178 -181 -180 -181 -181 -182 -30 244 234 232 230 -211 -210 -209 -28 -209 -28 -209 -35 277 266 263 259 -245 -244 -242 -241 -240 -240 -240 -40 309 298 295 293 -280 -279 -278 -277 -276 -275 -274 -45 343 333 330 327 -317 -316 -315 -314 -314 -313 -312 -50 379 369 365 362 -354 -353 -352 -351 -350 -349 -347 -55 414 403 440 397 -391 -390 -389 -388 -387 j-386 -385 -60 451 441 438 434 -428 -427 -426 -425 -424 -423 -422 -65 487 476 473 469 468 -464 -463 -462 -461 -460 -459 -70 524 513 510 507 505 -502 -501 -500 -498 -497 -496 -75 560 551 547 544 543 -539 -538 -537 -536 -535 -534 -80 560 560 56 560 560 560 -560 -560 -560 -560 -560 -560 Table 1 (Cont.) T# ## 208 224 240 256 272 288 304 320 336 352 368 -5 - 53 - 54 -55 -56 -57 -58 -59 -60 -61 -62 -63 -10 - 90 - 91 -92 -93 -95 -96 -97 -98 -100 -11 -102 -15 -123 -122 -124 -126 -127 -129 -130 -131 -133 -: 135 -135 -20 254 -155 -156 -157 -158 -160 -161 -162 -164 -166 -167 -25 -185 -185 -186 -186 -188 -190 -191 -192 -193 -195 -195 -30 -211 -210 -209 -215 -216 -218 -219 -221 -221 -223 -220 -35 -239 -239 -239 -240 -241 -242 -241 -244 -244 -242 -220 -40 -273 -272 -271 -270 -271 -271 -270 -272 -260 -242 -220 -45 -308 -307 -306 -305 -304 -303 -302 -283 -260 -242 -220 -50 -344 -343 -342 -341 -340 -340 -310 -283 -260 -242 -220 -55 -382 -381 -380 -378 -372 -341 -310 -283 -260 -242 -220 -60 -419 -418 -417 -404 -372 -341 -310 -283 -260 -242 -220 -65 -456 -455 -436 -404 -372 -341 -310 -283 -260 -242 -220 -70 -493 -468 -436 -404 -372 -341 -310 -283 -260 -242 -220 -75 -500 -468 -436 -404 -372 -341 -310 -283 -260 -242 -220 -80 -500 -468 -436 -404 -372 -341 -310 -283 -260 -242 -220 Table 2 - IFIELD T# ## 0 16 32 48 64 80 96 112 128 144 160 80 50.0 50.0 23.6 23.9 24.0 29.8 24.2 24.1 24.0 24.2 21.4 75 500 50.0 23.6 23.9 24.0 29.8 24.2 24.1 24.0 24.2 21.4 70 23.8 24.2 23.5 23.8 23.4 23.4 23.5 23.5 23.6 23.7 23.2 65 23.6 23.7 23.4 23.5 23.9 24.2 23.3 23.4 23.4 23.4 23.5 60 23.4 23.5 23.8 23.4 23.6 23.7 23.8 23.9 24.2 23.3 23.3 55 24.2 23.3 23.5 23.9 23.4 23.4 23.5 23.5 23.6 23.7 23.8 50 23.6 23.8 23.3 23.5 23.2 23.2 23.3 23.4 23.4 23.4 23.5 45 23.4 23.5 24.0 23.3 23.6 23.8 24.0 23.1 23.2 23.2 23.3 40 23.1 23.3 23.5 23.1 23.4 23.4 23.5 23.6 23.7 23.9 23.0 35 23.7 29.0 23.3 23.6 23.1 23.1 23.2 23.3 23.4 23.4 23.5 30 23.3 23.5 22.9 23.3 23.8 22.8 22.8 22.9 23.0 23.1 23.1 25 23.0 23.1 23.6 22.8 23.3 23.4 23.5 23.8 22.6 22.6 22.7 20 22.5 22.7 23.1 23.8 22.8 22.9 23.0 23.2 23.3 23.4 23.5 15 23.2 23.5 22.5 23.0 22.2 22.3 22.4 22.5 22.5 22.6 22.7 10 22.4 22.7 23.9 22.2 23.0 23.3 23.8 21.3 21.3 21.4 21.4 5 20.8 21.1 22.2 20.3 21.1 21.2 21.4 21.6 21.8 22.4 16.0 0 3.6 4.3 5.9 5.8 5.6 5.1 4.7 4.3 4.1 3.8 3.6 Table 2 (Cont.) T# ## 208 224 240 256 272 288 304 320 336 352 368 40 15.6 13.2 10.9 9.3 8.1 7.2 6.4 5.0 5.5. 5.1 37.5 14.2 10.9 9.3 8.1 7. 6.4 5.0 5.5 5.1 35 15.6 15.8 10.9 9.3 8.1 7.2 6.4 5.0 5.5 5.1 32.5 17.8 12.3 9.3 8.1 7.2 6.4 5.0 5.5 5.1 30 15.6 19.1 19.8 10.1 8.1 7.2 6.4 5.0 5.5 5.1 27.5 20.7 14.6 11.0 8.8 7.2 6.4 5.0 5.5 5.1 25 15.6 22.9 15.7 12.1 9.4 7.7 6.6 5.0 5.5 5.1 22.5 23.4 17.8 13.3 10.2 8.3 7.1 6.2 5.5 5.1 20 19.2 22.2 18.5 14.8 11.1 8.9 7.6 6.6 5.9 5.3 4.8 17.5 22.6 20.2 15.8 12.1 .7 8.1 7.0 6.2 6.6 5.1 15 23.3 23.2 23.4 17.0 13.0 10.5 8.8 7.5 6.7 5.9 5.4 12.5 21.3 21.2 18.0 13.0 11.4 9.5 8.0 7.1 6.3 5.7 10 22.2 21.3 21.2 18.4 14.8 11./8 10.0 8.5 7.6 6.7 6.1 7.5 21.6 21.3 15.0 13.4 12.9 10.5 9.1 7.8 7.1 6.4 5 21.3 16.3 14.7 13.4 12.4 11.4 10.7 9.0 8.0 7.3 6.8 2.5 17.9 18.7 19.0 8.5 13.7 8.2 9.0 7.0 7.2 6.7 0 3.0 2.8 2.7 2.6 2.6 2.5 2.4 2.3 2.3 2.2 2.1 Table 2 (Cont.) T# ## 0 16 32 48 64 80 96 112 128 144 160 -5 -6.3 -5.6 -5.4 5.0 4.9 4.7 4.5 4.4 4.2 4.1 4.0 -10 -8.8 -8.7 -8.2 8.6 8.2 8.1 7.8 7.5 7.3 7.1 6.9 -15 -1.8 -10.6 -10.3 11.3 11.3 11.0 1.7 10.5 10.2 10.0 9.7 -20 -12.5 -12.3 -12.0 14.2 13.9 13.8 13.8 13.8 13.5 12.7 12.5 -25 -14.4 -14.0 -13.8 -13.8 18.1 18.1 16.9 16.9 16.5 16.1 15.6 -30 -16.3 -16.0 -15.7 -15.3 20.6 20.6 20.6 20.5 20.1 19.9 19.5 -35 -18.1 -18.1 -18.1 -18.1 22.1 22.1 22.1 22.1 22.1 21.8 21.3 -40 -19.9 -19.9 -19.9 -19.6 22.8 22.8 22.8 22.8 22.8 22.8 22.8 -45 -21.0 -20.8 -20.6 -20.6 23.5 23.4 23.2 23.0 22.8 22.8 22.8 -50 -21.3 -21.3 -21.3 -21.3 23.5 23.5 23.5 23.5 23.5 23.5 23.5 -55 -22.1 -22.1 -22.1 -22.1 23.5 23.5 23.5 23.5 23.5 23.5 23.5 -60 -22.3 -22.1 -22.1 -22.1 23.9 23.9 23.9 23.9 23.9 23.9 23.7 -65 -22.8 -22.8 -22.8 -22.8 -22.8 23.9 23.9 23.9 23.9 23.9 23.9 -70 -22.8 -22.8 -22.8 -22.8 -22.8 23.9 23.9 23.9 23.9 23.9 23.9 -75 -22.8 -22.8 -22.8 -22.8 -22.8 23.9 23.9 23.9 23.9 23.9 23.9 -80 -23.5 -23.5 -23.5 -23.5 -23.5 23.9 23.9 23.9 23.9 23.9 23.9 Table 2 (Cont.) T# ## 208 224 240 256 272 288 304 320 336 352 368 -5 3.7 3.6 3.5 3.4 3.3 3.3 3.2 3.1 3.1 3.0 3.0 -10 6.3 6.1 6.0 5.8 5.6 5.5 5.4 5.3 5.2 5.1 4.0 -15 8.8 8.7 8.5 8.2 8.0 7.7 7.5 7.4 7.2 7.0 6.9 -20 11.5 11.3 11.1 10.7 10.4 1.1 9.9 9.6 9.3 9.0 8.8 -25 14.4 14.1 13.8 13.7 13.0 12.6 12.4 12.0 11.7 11.3 11.2 -30 18.1 18.1 18.1 16.6 16.1 15.6 15.1 14.6 14.4 13.9 13.5 -35 21.0 20.6 20.4 19.9 19.5 19.1 19.1 18.1 18.1 16.1 13.5 -40 22.1 22.1 22.1 22.1 21.6 21.3 21.3 20.6 19.2 16.1 13.5 -45 22.8 22.8 22.8 22.8 22.8 22.8 22.7 21.3 19.2 16.1 13.5 -50 23.5 23.5 23.5 23.5 23.5 23.2 22.8 21.3 19.2 16.1 13.5 -55 23.5 23.5 23.5 23.5 23.5 23.4 22.8 21.3 19.2 16.1 13.5 -60 23.5 23.5 23.5 23.5 23.5 23.4 22.8 21.3 19.2 16.1 13.5 -65 23.9 23.9 23.9 23.5 23.5 23.4 22.8 21.3 19.2 16.1 13.5 -70 23.9 23.9 23.9 23.5 23.5 23.4 22.8 21.3 19.2 16.1 13.5 -75 23.9 23.9 23.9 23.5 23.5 23.4 22.8 21.3 19.2 16.1 13.5 -80 23.9 23.9 23.9 23.5 23.5 23.4 22.8 21.3 19.2 16.1 13.5 Table 3 - VA T# ## 016 32 48 64 80 96 112 128 144 160 80 7.8 9.8 11.9 14.1 16.2 18.3 20.5 22.6 24.8 26.9 28.7 75 7.8 9.8 11.9 14.1 16.2 18.3 20.5 22.6 24.8 26.9 28.7 70 7.4 9.5 11.7 13.8 16.0 18.1 20.3 22.5 24.6 26.8 28.9 65 7.1 9.1 11.3 13.4 15.6 17.8 19.9 22.1 24.2 26.4 28.5 60 6.7 8.7 10.9 13.1 15.2 17.4 19.5 21.7 23.9 26.0 28.1 55 6.3 8.3 10.5 12.7 14.8 17.0 19.2 21.3 23.5 25.6 27.8 50 5.9 8.0 10.1 12.3 14.5 16.6 18.8 20.9 23.1 25.6 27.8 45 5.5 7.6 9.8 11.9 14.1 16.2 18.4 20.5 22.7 24.8 27.0 40 5.1 7.2 9.3 11.5 13.7 15.8 18.0 20.2 22.3 24.5 26.6 35 4.7 6.7 8.9 11.1 13.2 15.4 17.6 19.7 21.9 24.0 26.2 30 4.2 6.3 8.5 10.6 12.8 14.9 17.1 19.2 21.4 23.6 25.7 25 3.7 5.8 8.0 10.1 12.3 14.5 16.6 18.8 20.9 23.0 25.2 20 3.2 5.2 7.4 9.6 11.8 13.9 16.1 18.2 20.4 22.6 24.8 15 2.6 4.7 6.8 9.0 11.2 13.3 15.5 17.6 19.8 21.9 24.1 10 2.0 4.0 6.2 8.4 10.6 12.7 14.9 16.8 19.0 21.1 23.2 5 1.3 3.3 5.5 7.6 9.7 11.9 14.0 16.2 18.4 20.6 21.1 0 0.0 1.6 3.2 4.7 6.0 6.9 7.8 8.6 9.4 10.0 10.6 Table 3 (Cont.) T# ## 208 224 240 256 272 288 304 320 336 352 368 40 31.2 31.7 31.9 32.2 32.3 32.4 32.4 32.5 32.6 32.7 37.5 32.0 31.9 32.2 32.3 32.4 32.4 32.5 32.6 32.7 35 31.2 32.4 31.9 32.2 32.3 32.4 32.4 32.5 32.6 32.7 32.5 32.8 32.5 32.2 32.3 32.4 32.4 32.5 32.6 32.7 30 31.2 33.2 32.9 32.6 32.3 32.4 32.4 32.6 32.6 32.7 27.5 33.6 33.1 33.0 32.7 32.4 32.4 32.5 32.6 32.7 25 31.2 33.8 33.3 33.4 33.1 32.9 32.6 32.5 32.6 32.7 22.5 33.6 33.9 33.8 33.6 33.3 33.2 32.9 32.7 32.7 20 32.0 33.2 33.9 34.2 33.9 33.8 33.8 33.4 33.3 33.0 32.8 17.5 33.0 34.4 34.5 34.3 34.1 34.1 33.9 33.7 33.5 33.4 15 32.2 32.8 35.0 34.7 34.8 34.6 34.6 34.4 34.3 34.1 33.9 12.5 32.0 34.1 34.9 34.8 35.0 35.0 34.8 34.7 34.5 34.5 10 31.0 31.7 33.8 34.7 35.0 35.0 25.2 35.1 35.1 35.1 35.0 7.5 31.5 33.6 33.2 33.8 35.3 35.3 35.4 35.2 35.5 35.4 5 29.6 29.1 30.3 31.6 32.7 33.9 35.0 35.0 35.1 35.4 35.7 2.5 29.3 31.6 33.9 28.8 35.1 31.7 34.4 34.4 34.7 35.1 0 11.7 12.1 12.6 13.0 13.3 13.7 14.0 14.3 14.6 14.9 15.2 Table 3 (Cont.) T# ## 0 16 32 48 64 80 96 112 128 144 160 - 5 1.3 -0.2 -1.5 4.1 5.3 6.4 7.4 8.5 9.4 10.3 11.2 -10 2.1 0.2 -1.4 5.8 7.3 8.9 10.4 11.8 13.2 14.5 15.9 -15 2.7 0.8 -0.9 6.9 8.7 10.4 12.1 13.8 15.4 17.0 18.6 -20 3.3 1.3 -0.5 7.9 9.7 11.6 13.5 15.4 17.2 18.8 20.6 -25 3.8 1.8 -0.1 -2.1 10.9 12.9 14.8 16.7 18.6 20.5 22.3 -30 4.2 2.2 0.2 -1.7 11.9 14.0 16.0 18.1 20.1 22.1 24.1 -35 4.6 2.5 0.4 -1.6 12.9 15.0 17.1 19.2 21.3 23.4 25.4 -40 5.0 2.8 0.7 -1.4 14.0 16.1 18.2 20.3 22.4 24.5 26.7 -45 5.4 3.2 1.1 -1.1 15.2 17.4 18.5 21.6 23.7 25.8 27.9 -50 5.8 3.5 4.4 -0.7 16.6 18.7 20.8 22.9 25.0 27.1 29.2 -55 6.1 3.9 1.7 -0.4 18.1 20.2 22.3 24.4 26.5 28.6 30.7 -60 6.5 4.3 2.1 -0.1 19.7 21.8 23.9 26.0 28.1 30.2 32.3 -65 6.8 4.6 2.4 0.3 - 1.9 23.6 25.6 27.7 29.8 31.9 34.0 -70 7.2 5.0 2.8 0.6 - 1.5 25.5 27.6 29.6 31.7 33.8 35.9 -75 7.6 5.4 3.2 1.0 - 1.1 27.6 29.6 31.7 33.8 35.9 38.0 -80 8.0 5.8 3.6 1.4 - 0.8 29.8 31.9 34.0 36.0 38.1 40.2 Table 3 (Cont.) T# ## 208 224 240 256 272 288 304 320 336 352 368 - 5 13.6 14.3 15.0 15.7 16.4 17.1 17.7 18.4 19.1 19.7 20.3 -10 19.6 20.8 21.9 23.0 24.0 25.2 26.2 27.1 28.1 29.0 30.1 -15 23.1 24.7 26.0 27.3 28.7 30.0 31.2 32.5 33.7 34.8 36.1 -20 25.6 27.3 28.9 30.4 32.0 33.4 35.0 36.4 37.7 39.1 40.4 -25 27.7 29.5 31.3 33.1 34.6 36.2 37.9 39.4 41.0 42.5 44.2 -30 29.8 31.8 33.9 35.3 37.0 38.7 40.4 42.1 43.9 45.5 47.0 -35 31.6 33.5 35.6 37.4 39.4 41.2 43.3 44.9 46.9 47.5 47.0 -40 32.9 35.0 37.1 39.1 41.1 43.1 45.2 47.0 48.0 47.5 47.0 -45 34.2 36.3 38.4 40.5 42.6 44.7 46.8 47.7 48.0 47.5 47.0 -50 35.5 37.6 39.7 41.8 43.9 46.0 47.0 47.7 48.0 47.5 47.0 -55 37.0 39.1 41.2 43.3 45.2 46.1 47.0 47.7 48.0 47.5 47.0 -60 38.6 40.7 42.7 44.3 45.2 46.1 47.0 47.7 48.0 47.5 47.0 -65 40.3 42.4 43.6 44.3 45.2 46.1 47.0 47.7 48.0 47.5 47.0 -70 42.2 43.0 43.6 44.3 45.2 46.1 47.0 47.7 48.0 47.5 47.0 -75 42.5 43.0 43.6 44.3 45.2 46.1 47.0 47.7 48.0 47.5 47.0 -80 42.5 43.0 43.6 44.3 45.2 46.1 47.0 47.7 48.0 47.5 47.0 Table 4 - Expected Torque T# ## 0 16 32 48 64 80 96 112 128 144 160 80 73.6 73.6 73.1 72.7 72.5 72.4 72.2 72.1 71.9 71.8 70.5 75 73.6 73.6 73.1 72.7 72.5 72.4 72.2 72.1 71.9 71.8 70.5 70 70.0 70.0 70.0 70.0 70.0 70.0 70.0 70.0 70.0 70.0 70.0 65 65.0 65.0 65.0 65.0 65.0 65.0 65.0 65.0 65.0 65.0 65.0 60 60.0 60.0 60.0 60.0 60.0 60.0 60.0 60.0 60.0 60.0 60.0 55 55.0 55.0 55.0 55.0 55.0 55.0 55.0 55.0 55.0 55.0 55.0 50 50.0 50.0 50.0 50.0 50.0 50.0 50.0 50.0 50.0 50.0 50.0 45 45.0 45.0 45.0 45.0 45.0 45.0 45.0 45.0 45.0 45.0 45.0 40 40.0 40.0 40.0 40.0 40.0 40.0 40.0 40.0 40.0 40.0 40.0 35 35.0 35.0 35.0 35.0 35.0 35.0 35.0 35.0 35.0 35.0 35.0 30 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 25 25.0 25.0 25.0 25.0 25.0 25.0 25.0 25.0 25.0 25.0 25.0 20 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 15 15.0 15.0 15.0 15.0 15.0 15.0 15.0 15.0 15.0 15.0 15.0 10 10.0 10.0 10.0 10.0 10.0 10.0 10.0 10.0 10.0 10.0 10.0 5 5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0 0 0 0 0 0 0 0 0 0 0 0 0 Table 4 (Cont.) T# ## 208 224 240 256 272 288 304 320 336 352 368 40 44.6 39.3 35.3 32.2 29.8 27.7 25.9 24.2 22.6 21.2 37.5 37.6 35.3 32.2 29.8 27.7 25.9 24.2 22.6 21.2 35 44.6 35.0 32.2 29.8 27.7 25.9 24.2 22.6 21.2 32.5 32.5 32.5 32.2 29.8 27.7 25.9 24.2 22.6 21.2 30 44.6 30.0 30.0 30.0 29.8 27.7 25.9 24.2 22.6 21.2 27.5 27.5 27.5 27.5 27.5 27.6 25.9 24.2 22.6 21.2 25 44.6 25.0 25.0 25.0 25.0 25.0 25.0 24.2 22.6 21.2 22.5 22.6 22.6 22.6 22.6 22.6 22.6 22.6 22.6 21.2 20 40.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 19.9 17.5 17.6 17.6 17.6 17.6 17.6 17.6 17.6 17.6 17.6 17.5 15 30.0 15.0 15.0 15.0 15.0 15.0 15.0 15.0 15.0 15.0 15.0 12.5 12.5 12.5 12.5 12.5 12.5 12.5 12.5 12.5 12.5 12.5 10 20.0 10.0 10.0 10.0 10.0 10.0 10.0 10.0 10.0 10.0 10.0 7.5 7.5 7.5 7.5 7.5 7.5 7.5 7.5 7.5 7.5 7.5 5 10.0 6.0 6.0 6.0 6.0 6.0 6.0 6.0 6.0 6.0 6.0 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Table 4 (Cont.) T# ## 0 16 32 48 64 80 96 112 128 144 160 - 5 - 5.0 - 5.0 - 5.0 - 5.0 - 5.0 - 5.0 - 5.0 - 5.0 - 5.0 - 5.0 - 5.0 -10 -10.0 -10.0 -10.0 -10.0 -10.0 -10.0 -10.0 -10.0 -10.0 -10.0 -10.0 -15 -15.0 -15.0 -15.0 -15.0 -15.0 -15.0 -15.0 -15.0 -15.0 -15.0 -15.0 -20 -20.0 -20.0 -20.0 -20.0 -20.0 -20.0 -20.0 -20.0 -20.0 -20.0 -20.0 -25 -25.0 -25.0 -25.0 -25.0 -25.0 -25.0 -25.0 -25.0 -25.0 -25.0 -25.0 -30 -30.0 -30.0 -30.0 -30.0 -30.0 -30.0 -30.0 -30.0 -30.0 -30.0 -30.0 -35 -35.0 -35.0 -35.0 -35.0 -35.0 -35.0 -35.0 -35.0 -35.0 -35.0 -35.0 -40 -40.0 -40.0 -40.0 -40.0 -40.0 -40.0 -40.0 -40.0 -40.0 -40.0 -40.0 -45 -45.0 -45.0 -45.0 -45.0 -45.0 -45.0 -45.0 -45.0 -45.0 -45.0 -45.0 -50 -50.0 -50.0 -50.0 -50.0 -50.0 -50.0 -50.0 -50.0 -50.0 -50.0 -50.0 -55 -55.0 -55.0 -55.0 -55.0 -55.0 -55.0 -55.0 -55.0 -55.0 -55.0 -55.0 -60 -60.0 -60.0 -60.0 -60.0 -60.0 -60.0 -60.0 -60.0 -60.0 -60.0 -60.0 -65 -65.0 -65.0 -65.0 -65.0 -65.0 -65.0 -65.0 -65.0 -65.0 -65.0 -65.0 -70 -70.0 -70.0 -70.0 -70.0 -70.0 -70.0 -70.0 -70.0 -70.0 -70.0 -70.0 -75 -74.8 -75.0 -75.0 -75.0 -75.0 -75.0 -75.0 -75.0 -75.0 -75.0 -75.0 -80 -75.0 -76.5 -77.0 -77.4 -77.6 -77.8 -78.0 -78.1 -78.3 -78.4 -78.5 Table 4 (Cont.) T# ## 208 224 240 256 272 288 304 320 336 352 368 - 5 - 5.0 - 5.0 - 5.0 - 5.0 - 5.0 - 5.0 - 5.0 - 5.0 - 5.0 - 5.0 - 5.0 -10 -10.0 -10.0 -10.0 -10.0 -10.0 -10.0 -10.0 -10.0 -10.0 -10.0 -10.0 -15 -15.0 -15.0 -15.0 -15.0 -15.0 -15.0 -15.0 -15.0 -15.0 -15.0 -15.0 -20 -20.0 -20.0 -20.0 -20.0 -20.0 -20.0 -20.0 -20.0 -20.0 -20.0 -20.0 -25 -25.0 -25.0 -25.0 -25.0 -25.0 -25.0 -25.0 -25.0 -25.0 -25.0 -25.0 -30 -30.0 -30.0 -30.0 -30.0 -30.0 -30.0 -30.0 -30.0 -30.0 -30.0 -29.4 -35 -35.0 -35.0 -35.0 -35.0 -35.0 -35.0 -35.0 -35.0 -35.0 -33.6 -29.4 -40 -40.0 -40.0 -40.0 -40.0 -40.0 -40.0 -40.0 -40.0 -37.7 -33.6 -29.4 -45 -45.0 -45.0 -45.0 -45.0 -45.0 -45.0 -45.0 -41.9 -37.7 -33.6 -29.4 -50 -50.0 -50.0 -50.0 -50.0 -50.0 -50.0 -46.0 -41.9 -37.7 -33.6 -29.4 -55 -55.0 -55.0 -55.0 -55.0 -54.3 -50.2 -46.0 -41.9 -37.7 -33.6 -29.4 -60 -60.0 -60.0 -60.0 -58.4 -54.3 -50.2 -46.0 -41.9 -37.7 -33.6 -29.4 -65 -65.0 -65.0 -62.6 -58.4 -54.3 -50.2 -46.0 -41.9 -37.7 -33.6 -29.4 -70 -70.0 -66.7 -62.6 -58.4 -54.3 -50.2 -46.0 -41.9 -37.7 -33.6 -29.4 -75 -70.9 -66.7 -62.6 -58.4 -54.3 -50.2 -46.0 -41.9 -37.7 -33.6 -29.4 -80 -70.9 -66.7 -62.6 -58.4 -54.3 -50.2 -46.0 -41.9 -37.7 -33.6 -29.4

It is contemplated by the present invention that, through a conventional interpolation process, the above tables may be expanded to include more values corresponding to more frequent torque and speed intervals.

Within the motor control circuit 20 are closed loop control circuits for maintaining both the armature and the field current at desired values, namely, armature current control circuit 80 and field current control circuit 82, see Figs. 1 and 3. The outputs from these circuits are connected to the armature assembly 12 and the field assembly 14 of the motor 10. These circuits receive feedback inputs from current sensors associated with the motor control circuits 80, 82.

The armature current and adjusted field current setpoint values on the lines 40 and 42 are applied to closed-loop control circuits 80 and 82 after being converted to analog form by digital-to-analog converters 83 and 84, see Figs. 2 and 3. The two control circuits 80 and 82 include current delivery circuits including a bridge logic arrangement which apply switching signals to an arrangement of MOSFET devices that separately regulate the flow of current from a battery 90 to the field and armature coils F and A, respectively. The current delivery circuits of the control circuits 80 and <BR> <BR> <BR> <BR> 82 include current sensors 96 and 97 which generate feedback signals,/a feedback 93 and If feedback 94, respectively, proportional to the respective measured currents.

These feedback signals are applied to a pair of comparators 85 and 86 for comparison with corresponding setpoint values. The comparators 85 and 86 then generate an armature current error signal and a field current error signal, respectively.

A pair of amplifiers 87, 88 multiply the field current error signal and the armature current error signal by gain factors K2 and K3, respectively. These circuits cause a pair of pulse width modulated (PWM) drives to supply battery current to the motor coils in pulses of constant amplitude and frequency. The amplitude of the pulses varies as a function of the state of charge of the associated battery. The duty cycles of the pulses correspond to the respective setpoint values. This effectively sets the average field current and the average armature current so as to develop the desired torque in the armature.

It should be appreciated that the armature voltage, as represented by the

output of the comparator 72, will refiect flux losses. If there has been an unexpected loss of field flux, the torque generated by the motor will decrease. There will also be a concomitant decrease in the back EMF opposing the armature current driver, so the armature driver generates less average voltage to supply the demand for armature current. Therefore, in the present invention, actual armature voltage is compared to a desired armature voltage at a given torque and speed and is used to adjust the nominal field current value to achieve the desired actual torque.

Having described the invention in detail and by reference to preferred embodiments thereof, it will be apparent that modifications and variations are possible without departing from the scope of the invention defined in the appended claims.