TECHNICAL FIELD

The present invention relates to an actuating device interposable between an electric motor and an electric battery, and to an electric powertrain which uses it .

BACKGROUND ART

As known, many vehicles provided with electric motors are available to date. Specifically, the so- called electric vehicles are known, which are provided with one or more electric type engines, and the so- called hybrid vehicles are known, which are provided with at least one electric motor and at least one motor of a different type, typically an internal combustion engine . In the case of both electric vehicles and hybrid vehicles, the vehicle is equipped with an electric powertrain, having the function of moving the vehicle itself.

As shown by way of example in figure 1, an electric powertrain 1 comprises an electric battery 2, typically of the high-voltage type (in the order of 200- 400 Volts) , a master switch 4, electrically connected to the electric battery 2 , at least one power management unit 6 electrically connected to the master switch 4, and at least one electric motor 8, electrically- connected to the power management unit 6 , and operatively coupled to a corresponding wheel 10 of the vehicle (not shown) . In the case in point, the electric powertrain 1 shown in figure 1 comprises a first and second electric motors, indicated with 8a and 8b respectively, and operatively coupled to a first and second wheels, indicated with 10a, 10b respectively; furthermore, the electric powertrain 1 comprises a first and second power management units, respectively indicated with 6a and 6b, and respectively connected to the first and second electric motors 8a, 8b.

The electric powertrain 1 further comprises a voltage converter 12 of the DC/DC ("direct current/direct current") type, electrically connected to the electric battery 2 , and a further electric battery 14, of the low voltage type (typically capable of supplying a voltage approximately equal to 12V) and electrically connected to the voltage converter 12, so as to be charged by the electric battery 2. Furthermore, the electric powertrain 1 comprises an electronic control unit 16, electrically connected to the first and second power management units 6a, 6b, to the further electric battery 14, to the master switch 4 and to the voltage converter 12 , and in charge of superintending the operation of the electric powertrain 1.

In greater detail, the first and second power management units 6a, 6b present corresponding electric power inputs 20a and 20b, corresponding control inputs 22a and 22b, and corresponding electric outputs 24a and 24b. Instead, the first and second electric motors 8a, 8b- present corresponding power inputs 27a, 27b. Specifically, the power input 27a of the first electric motor 8a is connected to the electric output 24a of the first power management unit 6a, while the power input 27b of the second electric motor 8b is connected to the electric output 24b of the second power management unit 6b. The electric power inputs 20a, 20b of the first and second power management units 6a, 6b are instead connected to the master switch 4. Finally, the control inputs 22a, 22b of the first and second power management units 6a, 6b are connected to the electronic control unit 16.

Operatively, the master switch 4 electrically couples/uncouples in a controlled manner the first and second power management units 6a, 6b from the electric battery 2, e.g. in order to couple them to the electric battery 2 when the vehicle starts and uncouple them when the vehicle shuts off, or in case of accident. For practical purposes, when the master switch 4 is closed, the electric power inputs 20a, 20b of the first and second power management units 6a, 6b are electrically connected to the electric battery 2, and electric power is transferred from the electric battery 2 to the electric motors 8a, 8b, with a consequent application of torque on the vehicle wheels 10.

An example of a power management unit 6 is shown in. detail in figure 2, in which it is assumed that the master switch 4 is closed, and in which a voltage sensor 30 and a current sensor 31, arranged at the input of the power management unit 6 and in series to the electric battery 2, respectively, and connected to the electronic control unit 16 are further present. Instead, the further electric battery 14, the voltage converter 12 and the corresponding connections are not shown.

Specifically, the power management unit 6, the electric output 24 of which is connected to the electric motor 8, comprises a filter capacitor 32, an electric protection circuit 34 and a voltage converter of the DC/AC ("direct current/alternating current") type, which hereinafter will be referred to as the inverter 36. Furthermore, the electric power input 20 of the power management unit 6 is formed by a first and second terminals 40, 42, connected to the positive pole and to the negative pole of the electric battery 2, respectively .

In detail, the filter capacitor 32 and the electric protection circuit 34 are electrically connected between the first and second terminals 40, 42. Specifically, the electric protection circuit 34 comprises a protection diode D _p and a protection resistor R _p , connected in parallel between the first terminal 40 and a common node N _p , the cathode of the diode D _p being connected to the first terminal 40. The electric protection circuit 34 further comprises a protection transistor T _p , e.g. of the IGBT type, having the function of switch. More in detail, the collector of the protection transistor T _p is connected to the common node N _p ; the emitter is connected to the second terminal 42, while the gate is electrically connected to the electronic control unit 16.

The inverter 36 presents two electric input terminals electrically coinciding with the aforesaid first and second terminals 40, 42; furthermore, it presents an electric output coinciding with the electric output 24 of the power management unit 6. Again in greater detail, the inverter 36 comprises a first, a second and a third elementary units indicated by 50a, 50b and 50c, respectively.

Since the three elementary units 50a, 50b and 50c have the same structure, i.e. present the same components and the same electric connections, in the following only the first elementary unit 50a will be described for the sake of simplicity. Instead, with regards to the second and third elementary units 50b and 50c, the corresponding components are indicated with the numerals used for the corresponding components of the first elementary unit 50a, followed by letter b and by letter c, respectively.

More in detail, the first elementary unit 50a is interposed between the first and second terminals 40, 42, and presents an output node 56a, a first control terminal 58a and a second control terminal 60a. Furthermore, the first elementary unit 50a comprises a first and second diodes 62a and 64a, and a first and second transistors 66a and 68a, typically of the IGBT or MOSFET type. Again in greater detail, the cathode of the first diode 62a and the collector of the first transistor 66a are connected to the first terminal 40, while the anode of the first diode 62a and the emitter of the first transistor 66a are connected to the output node 56a. Furthermore, the cathode of the second diode 64a and the collector of the second transistor 68a are connected to the output node 56a, while the anode of the second diode 64a and the emitter of the second transistor 68a are connected to the second terminal 42. The first and second control terminals 58a, 60a are formed by the gates of the first and second transistors 66a, 68a, respectively, and are both electrically connected to the electronic control unit 16. Again with reference to figure 2, the output nodes 56a, 56b, 56c of the first, second and third elementary units 50a, 50b, 50c form the electric output of the inverter 36. Furthermore, the output nodes 56a, 56b, 56c are electrically connected to corresponding power terminals of the electric motor 8, indicated by 28a, 28b, 28c, respectively, and forming the power input 27 of the electric motor 8, which is thus, in the example shown, an electric motor with a three-phase input .

The electronic control unit 16 monitors the currents actually entering in the power terminals 28a, 28b, 28c of the electric motor 8 by means of appropriately current sensors (not shown) .

In addition to monitoring the currents entering the electric motor 8, the electronic control unit 16 controls the voltage present on the control terminals 58a-58c and 60a-60c, i.e. on the gates of the transistors 66a-66c and 68a-68c, so that such transistors work as switches.

More in detail, and considering the first elementary unit 50a, the electronic control unit 16 generates a first and second control signals si, s2, typically voltage signals, which are applied to the gate of the first transistor 66a and to the gate of the second transistor 68a, respectively. Both the first and second signals S _x , S ₂ are periodical with the same period T, also known as switching time, depending on the type of transistors used and on the electronic control unit 16. In the case of the example shown, and thus in the case of transistors IGBT, the switching frequency, i.e. the reverse of the switching time T, is approximately 2OkHz. As shown in greater detail in figure 3a, the first control signal S ₁ is such that, in a first sub- period Ti, it assumes a first value, e.g. ^w l" , while in a second sub-period T ₂ it assumes a second value, e.g. ^w 0", the sum of the first and second sub-periods T ₁ , T ₂ being equal to the period T. Specifically, the value "1" and the value "0" are such that the first transistor 66a is respectively either saturated or cut-off. In other words, the value "1" and the value "0" are not to be regarded as absolute, but must instead be understood as references to corresponding values, possibly also negative, so that the first transistor 66a is either saturated or off. As shown in figure 3b, the second control signal S ₂ is in phase with the first signal si. Furthermore, the second control signal S ₂ assumes value "0" , i.e. a value so that the second transition 68a is cut off in a time interval equal to the sum of the first sub-period T ₁ and a dead time Ta (being a much shorter time than T ₁ ) ; subsequently, in the time interval T ₃ comprised between T ₁ H-T _d and T, the second control signal S ₂ assumes the value "1", i.e. a value such that the second transistor 68a is saturated. Assuming, as usually the case, that the transistors of the inverter 36 are all of the same type, the values "0" and "1" are the same values mentioned with regards to the first control signal S ₁ . Regardless of this, the first and second transistors 66a and 68a are never conducting at the same time.

Similarly, the electronic control unit 16 generates a third and fourth control signals S ₃ , S ₄ , which are applied to the gate of the first transistor 66b and to the gate of the second transistor 68b of the second elementary unit 50b, respectively. Furthermore, the electronic control unit 16 generates a fifth and sixth control signals S ₅ , S ₆ , which are applied to the gate of the first transistor 66c and to the gate of the second transistor 68c of the third elementary unit 50c, respectively.

In detail, and again assuming that all the transistors in the inverter 36 are of the same type, the third and fourth control signals S ₃ , S ₄ are equal respectively to the first and second control signals S _x , S ₂ , but are offset with respect thereto by a number of degrees which depends on the type of electric motor 8 used; typically, such a number of degrees is essentially equal to 120°. Similarly, the fifth and sixth control signals S ₅ , S ₆ are the same as the first and second control signals Si, S ₂ , but are offset with respect thereto by a number of degrees essentially equal to 240° . Again with reference to the values ⁿ l" , "0", as mentioned, they must be understood as values of an electric quantity (typically, voltage) generated by the electronic control unit 16, and such that, when such a quantity is applied to a gate of a transistor, the transistor either conducts or is cut off, respectively. Therefore, the module and possibly the sign of the values "1", and ^u 0" depend on the type of transistors used and on the electronic control unit 16. Furthermore, electric powertrains are known in which, unlike that shown in figure 2, a corresponding driver circuit (not shown) is interposed between each gate of the transistors 66a-66c, 68a-68c and the electronic control unit 16, the input of which driver circuit is controlled by the electronic control unit 16, and the output of which driver circuit drives the gate of the corresponding transistor. In this case, the module and possibly the sign of the value ^w l" and of the value "0" also depend on the driver used.

Regardless of the implementation details, a conversion of direct voltage into alternating three- phase voltage is obtained by controlling the transistors of the elementary units 5Oa- 5Oc in the described manner. Specifically, the direct voltage supplied by the electric battery 2 to the power management unit 6 is converted into three alternating voltages, present at the output nodes 56a-56c of the power management units 6. Therefore, the three alternating voltages are applied to the power terminals 28a-28c of the electric motor 8, with a consequent generation of torque by the electric motor 8 , such a torque being applied to at least one wheel of the vehicle 10. A transfer of electric power is thus obtained from the electric battery 2 to the electric motor 8, and the vehicle is in a step of accelerating.

During a step of accelerating, the electric motor 8 behaves from the electric point of view as a resistive- inductive type load. Furthermore, the aforesaid power transfer can be increased/decreased by increasing/decreasing the time of the first sub-period T ₁ with respect to the second sub-period T ₂ ; specifically, the electronic control unit 16 typically acts so that Ti>T ₂ (and thus, Tχ>T ₃ ) . This means that during the step of accelerating, the control signals Si, S ₃ , S ₅ present a duty-cycle higher than 0.5, with the duty-cycle of a control signal being the ratio between the duration of the time interval in which the corresponding transistor is conducting and the period T. Instead, the control signals S ₂ , S ₄ , S ₆ present a duty- cycle shorter than 0.5.

Instead, when the vehicle is in a step of braking, the electric motor 8 behaves as a voltage generator, therefore it is possible to transfer electric power from the electric motor 8 to the electric battery 2, thus recharging the electric battery 2, in which a recharge current I of a continuous type enters, except for an inevitable ripple.

In order to optimize recharging, the electronic control unit 16 generally modifies the control signals Si-S ₆ so that Ti<T _3/ thus T ₁ -CT ₂ , occurs, i.e. so that the control signals S ₁ , S ₃ , S ₅ present duty-cycle lower than 0.5, and the signals S ₂ , S ₄ , s ₆ present duty-cycle higher than 0.5.

Since an excessive recharging current I may be generated during the step of braking, with a consequent risk of damaging the electric battery 2, the electronic control unit 16 makes use of the aforementioned voltage and current sensors 30, 31 to detect possible faults during the recharging process. In the case of faults, the protection of the electric battery 2 is entrusted to the electric protection circuit 34, which is controlled by the electronic control unit 16. More specifically, the electronic control unit 16 applies a control voltage V _c to the gate of the protection transistor T _p (figure 2) , or to a protection driver interposed between the gate of the protection transistor T _p and the electronic control unit 16 (case not shown) .

Specifically, during the step of accelerating, the control voltage V _c is such that the protection transistor T _p is cut off, so that the electric protection circuit 34 is not involved in the power transfer of the electric battery 2 to the electric motor 8.

During the step of braking, if the recharging occurs regularly, the control voltage V _c remains such that the power transistor T _p is cut off. On the other hand, if the voltage and current sensors 30, 31 indicate the occurrence of a fault, the control voltage V _c is such that the protection transistor T _p is saturated, with consequent creation of a conductive path arranged in parallel to the electric battery 2, dissipation of electric power in the protection resistor R _p and reduction of the recharging current I actually entering the electric battery 2.

Although the example shown in figure 2 refers to the case of electric motor 8 having power input 27 of the three-phase type, electric powertrains comprising electric motors with power inputs of the single-phase type are also known, consequently employing single-phase inverters, and thus with only two elementary units, and thus only two output nodes .

Operatively, the use of electric powertrains allows to obtain satisfactory performances in terms of torque, polluting emissions and range, however implies the need to periodically recharge the electric battery 2.- For this purpose, the possibility shown again in figure 1, which is characteristic of the so-called electric/hybrid vehicles of the plug- in type, is known for electrically connecting the electric battery 2 to an electric network 80, external to the vehicle. The connection between the electric battery 2 and the electric network 80 occurs by interposition of an AC/DC converter 82 arranged onboard the vehicle, or external thereto.

In detail, the electric network 80 may be a domestic electric network, and may thus employ a single- phase alternating voltage, with effective voltage equal to 230 V. In such a case, the AC/DC 12 converter is of the single-phase type, and is arranged so as to receive in input the alternating voltage provided by the electric network 80, and to output, i.e. in input to the electric battery 2, a continuous voltage, so as to recharge the electric battery 2.

Instead of a domestic electric network, it is further possible to use an industrial type electric network 80, i.e. an electric network employing a three- phase system, providing an AC/DC converter 82 of three- phase type is used.

The recharging scheme defined by the AC/DC converter 82 and by the arrangement of the AC/DC converter 82 with respect to the electric powertrain 1, i.e. by the connection present between the AC/DC converter 82 and the electric battery 2, has been proven efficient in many fields of application, however implies the need to employ an additional component with respect to the electric powertrain assembly 1. The use of such an additional component implies an increase of complexity, as well as, if the AC/DC converter 82 is arranged onboard the vehicle, an increase of weight and of size of the vehicle itself.

DISCLOSURE OF INVENTION

It is an object of the present invention to provide an electric powertrain which at least partially solves the drawbacks of the prior art. According to the present invention, an actuating device interposable between an electric motor and an electric battery, an electric powertrain, a vehicle and a recharging method of an electric battery are provided, as defined in claims 1, 15, 16 and 17, respectively.

In practice, the electric battery of an electric powertrain is charged by means of the inverter present in the power management unit of the electric powertrain, instead of employing an additional AC/DC converter with respect to the electric powertrain.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the invention, embodiments thereof will be described hereafter only by way of non- limitative example, and with reference to the accompanying drawings, in which: figure 1 shows a block chart of a known electric powertrain and a recharging scheme of a known type of such electric powertrain;

^' - figure 2 shows a detail of the circuit diagram in figure 1;

- figures 3a and 3b schematically show the time plot of the known control signals; - figure 4 shows a circuit diagram of an embodiment of the electric powertrain according to the present invention, and of the corresponding recharging scheme; figure 5 shows a perspective view of an electric connector according to the present invention;

- figure 6 shows a circuit diagram of a further embodiment of the electric powertrain according to the present invention, and of the corresponding recharging scheme;

- figure 7 shows a circuit diagram of a further embodiment of the electric powertrain according to the present invention, and of the corresponding recharging scheme .

BEST MODE FOR CARRYING OUT THE INVENTION

A first embodiment of the present electric powertrain is shown in figure 4, in which the components already present in figure 2 are indicated by means of the same numeral used above .

Specifically, the present electric powertrain is indicated by numeral 90 and comprises an onboard electric connector 92, which is electrically connected by means of corresponding electric connections

(indicated by 93a and 93b respectively) to two of the output nodes 56a- 56c of the power management unit 6 (in the case in point, the output nodes 56a, 56b) . The onboard electric connector 92 may mechanically and electrically connect to an external electric connector 94 for connecting to an electric network 80.

The electric powertrain 90 further comprises a switching device 95, e.g. a relay, interposed between the power management unit 6 on one side and the electric motor 8 and the onboard electric connector 92, on the other. Specifically, the switching device 95 presents first electrical terminals 96a electrically coinciding with corresponding output nodes 56a-56c of the inverter 36, second terminals 96b connected to the electric motor 8, and third terminals 96c connected to the onboard electric connector 92.

In detail, the switching device 95 controls the electric connections between the power terminals 28a-28c of the electric motor 8 and the output nodes 56a-56c of the power management unit 6; furthermore, it belongs to the electric connections 93a, 93b present between the onboard electric connector 92 and the power management unit 6, such electric connections 93a, 93b thus being also controlled by the switching device 95.

Even more in detail, the switching device 95 is such that, in a first operative condition, the power management unit 6 is electrically coupled to the electric motor 8, and uncoupled from the onboard electric connector 92, i.e. the first terminals 96a are electrically connected to the second terminals 96b, and are electrically disconnected from the third terminals 96c. Furthermore, the switching device 95 is such that, in a second operative condition, the power management unit 6 is electrically uncoupled from the electric motor 8, and electrically coupled to the onboard electric connector 92, i.e. the first terminals 96a (thus the output nodes 56a-56c) are electrically disconnected from the second terminals 96b, and are electrically connected to the third terminals 96c.

As described in greater detail below, the switching device 95 is controlled so that the switching device 95 is in the first operative condition when the vehicle is moving, or however not being recharged by the electric network 80; on the other hand, the switching device 95 is switched to the second operative condition when the electric battery 2 is to be recharged from the electric network 80.

In the embodiment shown in figure 4, the switching device 95, e.g. formed by a mechanically actuated relay (known in itself) , is mechanically coupled to the onboard electric connector 92, by which it is controlled. Specifically, the onboard electric connector 92 mechanically controls the switching device 95 so that the switching device 95 works in the aforesaid second operative condition when the onboard electric connector 92 itself is mechanically coupled to the external electric connector 94, while the switching device 95 operates in the aforesaid first operative condition when the onboard electric connector 92 is mechanically uncoupled from the external electric connector 94.

In this manner, it works according to the known art when the vehicle is not connected to the electric network 80. On the other hand, when the vehicle is connected to the electric network 80, the vehicle is recharged in the so-called plug-in mode, without needing to employ additional components. Indeed, when the vehicle is connected to the electric network 80, the electric motor 8 is uncoupled from the power management unit 6, and a number of output nodes 56a-56c (the output nodes 56a, 56b in the example shown) are put into electrical contact with the electric network 80. In such conditions, the inverter 36 behaves as an AC/DC. voltage converter and generates an essentially continuous voltage between its terminals 40, 42, with a consequent recharging of the electric battery 2.

It should be noted that in order to optimize the recharging process of the electric battery 2, the electronic control unit 16 can be programmed so that when the vehicle is connected to the electric network 80, it generates control signals Si-S ₆ with duty-cycles similar to those used for the corresponding control signals Si-S ₆ generated during the step of braking. In other words, it is possible to program the electronic control unit 16 so that when the vehicle is connected to the electric network 80, it generates control signals Si, S ₃ , s _Ξ with duty-cycles smaller than 0.5, and control signals S ₂ , S ₄ , S ₆ with duty-cycles greater than 0.5. In order to allow the electronic control unit 16 to determine when the vehicle is actually connected to the electric network 80, the switching device 95 can be connected to the electronic control unit 16, so that the electronic control unit 16 is able to determine if the switching device 95 is operating in the first or in the second operative condition.

It should also be noted that the embodiment shown in figure 4 refers to the case in which the electric network 80 is of the domestic type, i.e. the case in which the external electric connector 94 provides two single-phase poles, in addition to a possible ground pole, e.g. equal to 230 volt root mean square; such single-phase poles are arranged in electric contact by means of the onboard electric connector 92, with two output nodes 56a-56c of the power management unit 6, in the case in point the output nodes 56a, 56b.

By way of example only, figure 5 shows a possible embodiment of the onboard electric connector 92 in the case of domestic type electric network 80. In such an embodiment, the onboard electric connector 92 is similar to- an industrial socket compliant to International Electrotechnical Commission standard 309 (IEC 309) , and comprises a hollow cylinder 100, a flange 102, partially surrounding the hollow cylinder 100, and a grommet 104, also cylindrical and mechanically coupled to the hollow cylinder 100 by means of the flange 102. The hollow cylinder 100, the flange 102 and the grommet 104 are formed by insulating material, e.g. plastic.

Terminal portions of the electric connections 93a, 93b are accommodated inside the hollow cylinder 100 and the grommet 104 so that, when the onboard electric connector 92 is mechanically coupled to the external electric connector 94, such terminal portions of the electric connections 93a, 93b come into contact with the aforesaid two single-phase poles. A ground connection pole adapted to possibly come into contact with the ground pole of the external electric connector 94 may be present inside the hollow cylinder 100.

The hollow cylinder 100 further presents a coupling tooth 108 known in itself and adapted to favour the mechanical coupling with the external connector 94. The onboard electric connector 92 further comprises an actuating portion 110, arranged in contact with the coupling tooth 108, sliding with respect thereto and adapted to be pushed, when the external electric connector 94 is mechanically coupled to the onboard electric connector 92, through a groove 112 present in the flange 102 next to the coupling tooth 108, so as to at least partially protrude beyond the flange 102, in direction of the grommet 104. By choosing the switching device 95 and the position of the switching device 95 with respect to the actuating portion 11 in a manner known in itself, it is possible to obtain that when the external electric connector 94 is mechanically coupled to the onboard connector 92, the actuating portion 110 abuts against the switching device 95, taking it to the aforesaid second operative condition. Actuators or mechanical transmissions (not shown) may be possibly arranged between the actuating portion 110 and the switching device 95. The onboard electric connector 92 further comprises a spring (not shown) , mechanically coupled to the flange 102 and to the actuating portion 110 so that when the external electric connector 94 is uncoupled from the onboard electric connector 92, the actuating portion 110 is returned in direction of the hollow cylinder 100, without protruding beyond the flange 102 any longer. In this manner, the switching device 95 is returned to the aforesaid first operative condition.

Regardless of the implementation details of the onboard electric switch 92, the electric powertrain 90 shown in figure 4 allows, in presence of an electric network 80 capable of providing approximately 230 volt root mean square, to theoretically recharge the electric battery 2 at voltages in the order of 320 volts.

Figure 6 shows a further embodiment related to the case in which the electric network 80 is of the industrial type, and thus the external electric connector 94 presents, in addition to a neutral pole (irrelevant for the purposes of the present invention) , three poles related to the three-phases of the industrial electric network.

Specifically, all the three output nodes 56a-56c of the power management unit 6 are here connected to the onboard electric connector 92 by means of the electric connections 93a- 93c. The switching device 95 is arranged in a manner similar to that shown above, and also controls the electric connection 93c. In this manner, when the switching device 95 is in the aforesaid second operative condition, each of the three output nodes 56a- 56c is arranged in electric contact with a corresponding pole of the external electric connector 94, such a pole being associated to a corresponding phase of the electric network 80.

The electric powertrain 90 shown in figure 6 comprises a further voltage sensor 115, interposed between the onboard electric connector 92 and the switching device 95. The voltage sensor 115 is in electric contact with the onboard electric connector 92, and is connected to the electronic control unit 16; furthermore, when the voltage sensor 115 detects the coupling between the onboard electric connector 92 and the external electric connector 94 , it sends a coupling signal to the electric control unit 16.

Unlike that described above with respect to the embodiment shown in figure 4, the switching device 95 is here controlled by the electronic control unit 16; for example, the switching device 95 is formed by an electronically actuatable relay and controlled by the electronic control unit 16. The onboard electric connector 92 may thus be formed by a common electric socket of the three-phase type (known in itself) .

The other elements of the electric powertrain 90 are the same as those present in figure 4 and will therefore not be described again.

From an operative point of view, the further voltage sensor 115 detects if the onboard electric connector 92 is connected to the external electric connector 94 , and informs the electronic control unit 16, sending the coupling signal. In turn, the electronic control unit 16 controls the switching device 95 so that when the onboard electric connector 92 is connected to the external electric connector 94, the switching device 95 works in the aforesaid second operative condition, otherwise it works in the aforesaid first operative condition.

It is worth noting that also in the case of three-phase type external electric network, embodiments are possible in which the switching device 95 is mechanically controlled by the onboard electric connector 92 in a manner similar to that described above .

It should also be noted that the electric powertrain 90 shown in figure 6 allows, in presence of an electric network 80 of the three-phase type and capable of supplying approximately 400 volts root mean square between phases, to theoretically recharge the electric battery 2 at voltages in the order of 560 volts . Figure 7 shows a further embodiment of the present electric powertrain 90, which allows to recharge the electric battery 2 at voltages higher than those which can be obtained in theory on the basis of the features of the electric network 80. Here, the first electric powertrain 90 comprises a first, a second and a third additional diode, indicated by 120a-120c, respectively. The anodes of the first, second and third additional diodes 12Oa-12Oc are electrically connected respectively to the output nodes 56a-56c of the power management unit, here indicated by numeral 129, while the cathodes are connected to a same boost node 125. Furthermore, instead of the electric protection circuit 34, the power management unit 129 comprises a dual function electric circuit 130, which is similar to the previously described electric protection circuit 34, but further comprises an inductor L and a switch I _p . Specifically, the switch I _p , e.g. formed by an electromechanical baffle or an electromechanical switch, is controlled by the electronic control unit 16 and is arranged so that, in a first state, it connects the protection resistor R _p to the collector of the protection transistor T _p while, in a second state, it connects the collector of the protection transistor T _p to a first pole of the inductor L. A second pole of the inductor L is instead connected to the boost node 125.

From an operative point of view, when the switch I _p is in the first state, the dual function electric circuit 130 becomes structurally and functionally similar to the electric protection circuit 34. Therefore, according to the state of the transistor T _p (conducting or cut off) , it allows to avoid damage to the electric battery 2. On the other hand, when the switch I _p is in the second state, the dual function electric circuit 130 becomes a so-called electric boost circuit. In detail, assuming that the switch I _p is in the second state, and defining the voltage present on the boost node 125 as boost voltage V ₅ , a mesh comprising the protection transistor T _p and the inductor L is formed when the protection transistor T _p is conducting. A boost current I _B circulates in such a mesh. When the protection transistor T _p is cut off instead, the aforesaid mesh opens and the boost current I _B flows towards the protection diode D _p , and thus the electric battery 2, regardless of the voltage at the terminals of the electric battery 2 itself. Therefore, by alternating periods in which the protection transistor T _p is conducting to periods in which the protection transistor T _p is cut off, e.g. according to a pulse width modulation technique (PWM) , the electric battery 2 can be recharged at a voltage higher than that which can be theoretically obtained on the basis of the features (voltage) of the electric network 80.

From the operative point of view, when the vehicle is not connected to the electric network 80, the electronic control unit 16 controls the switch I _p so that in the first state, in a manner known in itself, neither the additional diodes 12Oa- 12Oc, nor the inductor L intervene in the operation of the powertrain 90. On the other hand, either when the vehicle is connected to the electric network 80, or during the step of braking (if the electronic control unit 16 detects no faults or overloads of the electric battery 2) , the electronic control unit 16 controls the switch I _p so that it is in the second state, and that the dual function electric circuit 130 can work as electric boost circuit . It should also be noted that, although figure 7 explicitly refers to the case of electric network 80 of the three-phase type, embodiments provided with the dual function electric circuit 130 are provided and configured to electrically couple with the electric networks of the single-phase type. Such embodiments are provided with only two additional diodes, connected to two output nodes of the power management unit 129, and to the onboard electric connector 92, respectively.

The described electric powertrain 90 thus allows to recharge the electric battery 2 by means of an external electric network, without needing to use additional voltage converters with respect to the inverter 36.

It is finally apparent that changes and variations can be made to the described electric powertrain without however departing from the scope of the present invention, defined by the accompanying claims .

Specifically, embodiments are possible in which the electric motor 8, and consequently also the inverter 36 are of the single-phase type, in which case either a single-phase type electric network 80, or a three-phase type electric network 80 and an appropriate adapter (not show) of the type known in itself are used. In this case, if present, only two additional diodes 12Oa-12Oc are sufficient.

Furthermore, embodiments provided with the dual function electric circuit 130 are possible, but without the additional diodes 12Oa-12Oc, in which case the inductor L may be connected to a low voltage source (not shown) , e.g. formed by solar panels arranged aboard the vehicle, instead of the boost node 125. Embodiments are further possible in which the switching device 95 does not uncouple the power management unit from the onboard electric connector 92 in the first operative condition. Similarly, embodiments are possible in which the switching device 95 does not electrically uncouple the power management unit from the electric motor 8 in the second operative condition; in such embodiments, appropriate mechanisms may be used (not shown) adapted to block the electric motor 8 during the step of recharging. Finally, the present the electric powertrain 90 may be used also in the case of vehicles equipped with two or more electric motors, each associated to a corresponding power management unit, as shown for example in figure 1. In this case, the switching device 95 is preferably interposed between each electric motor and each corresponding power management unit . In such a manner, each power control unit is connected by means of the switching device 95 to the onboard electric connector 92 according to any previously described embodiment. Consequently, according to the adopted embodiment, two or three output nodes 56a-56c of each of the aforesaid power management units are in electric contact with corresponding output nodes of the other power management units, in addition to being connected to the onboard electric connector 92 by means of the switching device 95.