FIELD OF INVENTION

[0001] The present subject matter is related to, in general, motor systems and, in particular, control of motor systems. BACKGROUND

[0002] A Capacitor start and run (CSR) motor is used to drive a low- power pump, such as a pump with a power rating of up to 1.5 Horse Power (HP). The pump is used to pump liquids, such as water, from one place to another, such from a well to an overhead tank. The CSR motor has a capacitor to facilitate starting and running of the motor.

BRIEF DESCRIPTION OF DRAWINGS

[0003] The detailed description is provided with reference to the accompanying figures. In the figures, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears. The same numbers are used throughout the drawings to reference like features and components.

[0004] Fig. 1 illustrates a motor system, in accordance with an implementation of the present subject matter;

[0005] Fig. 2 illustrates a method for controlling a motor, in accordance with an implementation of the present subject matter; and

[0006] Fig. 3 illustrates a method for controlling a motor, in accordance with an implementation of the present subject matter.

DETAILED DESCRIPTION

[0007] A Capacitor start and run (CSR) motor is used in low power applications, such as for driving a pump with a power rating of up to 1.5 HP. A CSR motor converts electrical energy into mechanical energy to drive the pump. The CSR motor incudes a stator, a rotor, and a capacitor. The stator includes a first stator winding and a second stator winding. The capacitor facilitates starting and running of the motor by creating a phase difference between the current supplied to the first stator winding and the second stator winding.

[0008] In some scenarios, such as failure of a bearing of the motor, deposition of debris on the pump, and the unavailability of adequate amount of liquid pumped by the pump (i.e., a dry run condition), the motor experiences extreme load conditions, such as an overload condition, or an underload condition. The extreme load conditions cause over-heating of the motor and may eventually lead to the failure of the motor. To prevent the motor from the getting damaged due to the extreme load conditions, the extreme load conditions are to be detected and the current supply to the motor has to be cut off upon the detection.

[0009] In this regard, in some cases, to detect the overload condition and to subsequently stop the current supply, a thermal overload protector is used. The thermal overload protector has a thermal sensor to detect the temperature of the motor. When the current supplied to the motor increases, the temperature of the motor increases. When the temperature increases beyond an allowable value, the thermal overload protector opens to stop the current supply to the motor. However, the increase in temperature of the motor due to the increase in current may happen gradually. Therefore, the thermal overload protector takes time to detect the overloading condition, and thereby the protection of the motor may be hampered.

[0010] Further, in some cases, to detect the dry run condition of the pump and thereby, to identify the underload condition of the motor, a dry run sensor is used. The dry run sensor may include a dry run probe and may detect the dry run condition when the liquid level falls below a threshold level (which causes the dry run probe to become dry). However, due to the adhesive force between the probes and the liquid, the dry run probes may tend to remain wet despite the liquid level falling below the threshold. Accordingly, accurate detection of the underload condition of the motor may not be possible.

[001 1 ] The present subject matter relates to integrated pump controller. With the implementations of the present subject matter, the motor and the pump may be prevented from getting damaged due to extreme load condition.

[0012] In accordance with an example implementation, a motor system may include a motor. The motor may include a stator. The stator may have a first stator winding. The motor system may include a relay, which may be connected in series with the first stator winding. An integrated controller may be coupled to the relay and may control the relay.

[0013] In an example, the motor system may detect the overload condition and the underload condition based on power supplied to the motor. For estimating the power supplied, the integrated controller may acquire a plurality of samples of the voltage supplied to the motor and a plurality of samples of the current supplied to the motor. Further, the integrated controller may estimate the power based on the acquired plurality of samples of the voltage and the acquired plurality of samples of the current. The integrated controller may detect the overload and the underload condition based on a comparison of the power with a first power threshold and a second power threshold and switch off the relay upon the detection. For instance, the estimated power being less than the first power threshold indicates the underload condition and the power being higher than the second power threshold indicates the overload condition. The integrated controller may switch off the relay to turn off the motor if the power is less than the first power threshold or if the power is higher than the second power threshold. Accordingly, the motor system protects the pump during extreme load conditions.

[0014] The present subject matter prevents the malfunctioning and failure of the motor system caused due to the extreme load conditions, such as an overload condition and an underload condition. Further, by computing the power supplied to the motor and utilizing the computed power to estimate the extreme load condition, the present subject matter detects the extreme loading conditions instantaneously and prevents a time lag between the occurrence of the extreme loading conditions and the detection. The present subject matter eliminates use of separate components, such as the dry run sensor, to detect the underload condition of the motor. The present subject matter facilitates fast, safe, and efficient protection of the motor.

[0015] The present subject matter is further described with reference to Figs. 1 -3. It should be noted that the description and figures merely illustrate principles of the present subject matter. Various arrangements may be devised that, although not explicitly described or shown herein, encompass the principles of the present subject matter. Moreover, all statements herein reciting principles, aspects, and examples of the present subject matter, as well as specific examples thereof, are intended to encompass equivalents thereof.

[0016] Fig. 1 illustrates a motor system 100, in accordance with an implementation of the present subject matter. The motor system 100 may be coupled to input power supply lines 102 and 104 to supply electric current, hereinafter referred to as current, to the motor system 100. The motor system may include a motor 106. The motor 106 may include a stator and a rotor (not shown in Fig. 1 ). The stator may include a first stator winding 108 and a second stator winding 1 10. The first stator winding 108 may be referred to as a start winding and the second stator 1 10 winding may be referred to as a run winding. The second stator winding 1 10 may be connected in parallel to the first stator winding 1 08. The first stator winding 108 and the second stator winding 1 10 may be positioned perpendicular to each other on the stator. A pump (not shown in Fig. 1 ) may be coupled to the motor 106 to be driven by the motor 106. In particular, the rotor may be coupled to a shaft of the pump. The pump may pump liquid from a liquid source to another place. For instance, the pump may pump liquid from a well to an overhead tank.

[0017] The motor system 100 may include a relay 1 12. The relay 1 12 may be connected between the motor 106 and the input power supply line 102 to control the flow of current to the motor 106. In an example, the relay 1 12 may be solid-state relay, mechanical relay, or another type of relay.

[0018] The motor system 100 may include a capacitor 1 14. The capacitor 1 14 may be connected between and in series to the relay 1 12 and the start winding 108. The capacitor 1 14 may facilitate both starting and running of the motor 106. Accordingly, another capacitor is not used specifically for starting of the motor 106. The capacitor 1 14 is permanently connected to the start winding 108 during operation. That is, the capacitor 1 14 does not get disconnected from the start winding 108 after the motor 106 attains full speed. Since, the motor system 100 includes a single capacitor for causing starting and running of the motor 106, the motor system 100 may be referred to as the capacitor start and run (CSR) motor system.

[0019] During operation, the run winding 1 10 may receive the current supply from the relay 1 12. Further the capacitor 1 14 may receive the current supply from the relay 1 12 and may provide current to the start winding 108. The connection of the start winding 108 to the capacitor 1 14 creates a phase difference between the current supplied to the start winding 1 08 and that supplied to the run winding 1 10. The phase difference created by the capacitor 1 14 may provide sufficient torque to facilitate starting of the motor 106 and may keep the motor 106 running subsequently. For instance, the phase difference creates a rotating magnetic field that rotates the rotor and the rotor keeps rotating till the current supply to the motor 106 is cut off.

[0020] The motor system 100 may include a controller 1 16. The controller 1 16 may be implemented as a microprocessor, a microcomputer, a microcontroller, a digital signal processor, a state machine, a logic circuitry, and/or a device that manipulate signals based on operational instructions. Among other capabilities, the controller 1 16 may fetch and execute computer-readable instructions stored in a memory (not shown in Fig. 1 ), such as a volatile memory (e.g., RAM) or a non-volatile memory (e.g., EPROM, flash memory, Memristor, etc.), of the controller 1 16. The controller 1 16 may be coupled to the relay 1 12.

[0021 ] The controller 1 16 may include an input/ output interface 1 18. The input/output interface 1 18 may include a variety of machine-readable instructions-based interfaces and hardware interfaces that allow the controller 1 16 to interact with different entities of the motor system 100, such as the relay 1 12. Further, the input/output interface 1 18 may enable the components of the controller 1 16 to communicate with computing devices, web servers, and external repositories. The interface may facilitate multiple communications within a wide variety of networks and protocol types, including wireless networks, wireless Local Area Network (WLAN), RAN, satellite-based network, etc.

[0022] The controller 1 16 may protect of the motor 106 from conditions that may damage the motor 106, such as an overload condition, and an underload condition. In the underload condition, the power supplied to the motor 106 is lesser than a first power threshold of a rated power range of the motor 106. In the overload condition, the power supplied to the motor 106 is higher than a second power threshold of the rated power range of the motor 106. The rated power range may be determined based on a mathematical product of a rated current range and a rated voltage range. The rated current range may be a range of current that the motor 106 is designed for and that the motor 106 should be supplied with for normal operation of the motor 106 and the rated voltage range may be a range of voltage that the motor 106 is designed for and that the motor 106 should be supplied with for normal operation of the motor 106. The rated current range may have a first current threshold as its lower limit and a second current threshold as its upper limit. The rated voltage range may have a first voltage threshold as its lower limit and a second voltage threshold as its upper limit. The rated power range may have the first power threshold as its lower limit and the second power threshold as its upper limit. Since, the rated power range may be determined based on the mathematical product of the rated voltage range and the rated current range, the first power threshold may be determined based on a mathematical product of the first current threshold and the first voltage threshold and the second power threshold may be determined based on a mathematical product of the second current threshold and the second voltage threshold.

[0023] In order to protect the motor 106, the controller 1 16 may acquire samples of voltage A supplied to the motor 106 and current B supplied to the motor 106. Based on a plurality of samples of the voltage and a plurality of samples of current, the controller 1 16 may estimate power supplied to the motor 106. For instance, the controller 1 16 may determine a root mean square value (RMS) value of the voltage and an RMS value of the current supplied to the motor 106.

[0024] In some cases, the motor 106 may get damaged due to an undervoltage condition or an overvoltage condition. The undervoltage condition may be a condition where the voltage falls below the rated voltage range of the motor 106. The overvoltage condition may be a condition where the voltage is higher than a rated voltage range. The undervoltage condition may result in reduced starting ability of the motor 106, decrease in performance, and reduced efficiency of the motor 106, while the overvoltage may result in overheating of the motor 106 and failure of the motor 106. To protect the motor 106 from the overvoltage condition and the undervoltage condition, the controller 1 16 may switch off the relay 1 12 if it detects the overvoltage condition or the undervoltage condition, as will be described with reference to Fig. 2 and Fig. 3.

[0025] To detect the overload condition and the underload condition, the controller 1 16 may compare the estimated power with the first power threshold and the second power threshold. The estimated power being less than the first power threshold may indicate the underload condition and the estimated power being higher than the second power threshold may indicate the overload condition. For an ideal operation of the motor 106, the power should be between the first power threshold and the second power threshold. Therefore, the controller 1 16 may switch off the relay 1 12 to turn off the motor 106 if the estimated power is less than the first power threshold or if the estimated power is more than the second power threshold.

[0026] In an example, the controller 1 16 may display various parameters associated with the operation of the motor 106, such as the values of voltage supplied to the motor 106, and values of current supplied to the motor 106 on a display unit 120 of the motor system 100. The display unit 120 may include, for example, a liquid crystal display (LCD) display, a light emitting diode (LED) display, or the like.

[0027] As mentioned above, the controller 1 16 may perform functions, including protecting the motor 106 from overload condition, underload condition, overvoltage condition, undervoltage condition, and displaying of values of the samples of the voltage and the current. Accordingly, the controller 1 16 may be referred to as the integrated controller.

[0028] Fig. 2 illustrates a method 200 for controlling the motor 106, in accordance with an implementation of the present subject matter. The order in which the method 200 is described is not intended to be construed as a limitation, and any number of the described method blocks may be combined in any order to implement the method 200 or an alternative method. Furthermore, the method 200 may be implemented by processor(s) or computing device(s) through any suitable hardware, non-transitory machine-readable instructions, or a combination thereof. The method 200 may be utilized in the motor system 100. Further, the steps of the method 200 may be performed by controller 1 16.

[0029] Referring to the Fig. 2, at block 202, the operation of the controller 1 16 may be initialized, for example, with the switching on of the motor 106, at block 202. In an example, a first plurality of samples of the current and a first plurality of samples of the voltage per cycle of the input voltage are to be used for an accurate determination of the RMS value of the current and the RMS value of the voltage respectively. The first plurality of samples of the voltage and the first plurality of samples of the current may be, for example, 20. Accordingly, if the input AC voltage has a frequency of 50 Hz, 1000 samples are to be acquired per second. That is, one sample of current and one sample of voltage is to be acquired in each millisecond.

[0030] In this regard, to acquire a sample of the voltage and a sample of the current periodically, at block 204, the controller 1 16 may determine if a first period has expired. The first period may be, for example, 1 milli second. To determine if the first period has expired, a first interrupt may be utilized. The first interrupt may alert the controller 1 16 to acquire samples of the current and samples of the voltage periodically, i.e., upon expiry of the first period.

[0031 ] If the first period has expired, the controller 1 16 may acquire a sample of the current and a sample of the voltage, at block 206. Further, at block 206, the controller 1 16 may increment the sample count by one upon acquiring the sample of the voltage and the sample of the current, to keep track of the number of samples acquired so far.

[0032] Further, as mentioned earlier, for accurate determination of the RMS value of the voltage and the RMS value of the current, the first plurality of samples of the voltage and the first plurality of samples of the current may be required. Accordingly, at block 208, the controller 1 16 may determine if the first plurality of samples of the voltage and the first plurality of samples of the current are acquired. To determine if the first plurality of samples of the voltage and the first plurality of samples of the current are acquired, the controller 1 16 may determine if the sample count equals the first plurality of samples. For instance, if the sample count is 20, the controller 1 16 may determine if the 20 samples of current and 20 samples of voltage are acquired. The controller 1 16 may store the first plurality of samples of the current and the first plurality of samples of the voltage. [0033] In an example, the controller 1 16 may display the values of the samples of the voltage and the values of the samples of the current on the display unit 120. The display unit 120 may be refreshed at a frequency lesser than the frequency at which the samples are acquired due to the limitations in the refresh rate of the display unit 120. Accordingly, the display unit 120 may be updated periodically with values of the samples of the voltage and the samples of current at a second period, which is based on the refresh rate of the display unit 120. The second period may be greater than the first period. In an example, the second period may be 5 milli second. The samples may be acquired once in 1 millisecond and the display unit 120 may be refreshed once in 5 milli second. That is, the display unit 120 may display values of five samples of current and five samples of the voltage. To update the display unit 120 periodically, at block 210, the controller 1 16 may determine if the second period has expired. To determine if the second period has expired, the controller 1 16 may utilize a second interrupt. If it is determined that the second period has expired, at block 212, the controller 1 16 may update the display unit 120 with the values of samples of the voltage and the values of samples of the current acquired.

[0034] When the first plurality of samples is acquired, at block 214, the controller 1 16 may compute the RMS value of the voltage based on the first plurality of samples of the voltage and the RMS value of the current based on the first plurality of samples of the current. Furthermore, the controller 1 16 may estimate the power based on the RMS value of the voltage and the RMS value of the current. For instance, the controller 1 16 may compute a product of the RMS value of the current and RMS value of the voltage to obtain the power. Also, at block 214, the controller 1 16 may reset the sample count for the next cycle.

[0035] As mentioned earlier, the controller 1 16 may detect the overvoltage condition and the undervoltage condition and may protect the motor 106 by switching off the relay 1 12 upon the detection. Accordingly, to detect the overvoltage and the undervoltage condition, at block 216, the controller 1 16 may determine if the obtained RMS value of the voltage is within the rated voltage range. The controller 1 16 may store the rated voltage range of the motor 106, i.e., the first voltage threshold and the second voltage threshold. In an example, the first voltage threshold may be 180 V and the second voltage threshold may be 250 V.

[0036] If the RMS value of the voltage is determined to be outside of the rated voltage range, i.e., the RMS value is either higher than the second voltage threshold or lower than the first voltage threshold, at block 218, the controller 1 16 may switch off the relay 1 12. This is because, the RMS value of the voltage being higher than the second voltage threshold indicates the overvoltage condition and the RMS value of the voltage being lower than the rated voltage indicates undervoltage condition. By switching off the relay 1 12, the controller 1 16 may stop the current supply to the motor 106 and thereby, the motor 106 may be turned off.

[0037] If the RMS value of the voltage is determined to be within the rated voltage range, then the controller 1 16 may repeat the step at block 214 to compute the RMS value of the voltage based on subsequent samples of voltage to be able to protect the motor 106 whenever the RMS value of the voltage is outside of the rated voltage range.

[0038] Further, the controller 1 16 may protect the motor 106 from extreme load conditions, such as the overload condition and the underload condition. In an example, to protect the motor 106 from the extreme load condition, the controller 1 16 may utilize the power supplied to the motor 106, which is computed at block 214.

[0039] At block 220, the controller 1 16 may determine if the power supplied to the motor 106 is less than the first power threshold. In an example, the controller 1 16 may determine if the power supplied to the motor 106 is less than the first power threshold for a first time. The first time may be, for example, 15 s. If it is determined that the power is less than the first power threshold, the controller 1 16 may switch off the relay 1 12, at block 218, since the power being less than the first power threshold indicates the underload condition. However, if it is determined that the power is higher than the first power threshold, the controller 1 16 may repeat the step at block 214 to compute the power based on subsequent samples of the current and subsequent samples of the voltage to be able to protect the motor 106 whenever the power is less than the first power threshold. In an example, the first power threshold may be stored in the controller 1 16.

[0040] Further, at block 222, the controller 1 16 may determine if the power is higher than the second power threshold. In particular, the controller 1 16 may determine that the power is higher than the second power threshold for a second time, such as 15 s. If the controller 1 16 determines that the power is higher than the second power threshold, the controller 1 16 may switch off the relay 1 12 to turn off the motor, at block 218. This is because the power being high than the second power threshold indicates the overload condition. If the controller 1 16 determines that the power is less than the second power threshold, the controller 1 16 may repeat the step at block 214 to compute the power based on subsequent samples of the current and subsequent samples of the voltage to be able to protect the motor 106 whenever the power is higher than the second power threshold. In an example, the second power threshold and the second time may be stored in the controller 1 16.

[0041 ] Fig. 3 illustrates a method 300 for controlling the motor 106, in accordance with an implementation of the present subject matter. The order in which the method 300 is described is not intended to be construed as a limitation, and any number of the described method blocks may be combined in any order to implement the method 300 or an alternative method. Furthermore, the method 300 may be implemented by processor(s) or computing device(s) through any suitable hardware, non-transitory machine-readable instructions, or a combination thereof. The method 300 may be utilized in the motor system 100. Further, the steps of the method 300 may be performed by controller 1 16. [0042] At block 302, the controller 1 16 may receive motor system 100 initialization instruction. The initialization instruction may be, for example, the turning on of the motor 106. In another example, the motor initialization instruction may be an intimation that a time slot in which the motor 106 is to be operated in an auto mode of the motor 106 has commenced. The auto mode and the time slot will be explained with reference to blocks 310-314.

[0043] At block 304, the controller 1 16 may switch on the relay 1 12 upon initializing the motor system 100. Subsequently, at block 306, the controller 1 16 may determine the voltage based on a plurality of samples of the voltage. For instance, the controller 1 16 may determine the RMS value of the voltage based on the first plurality of samples of the voltage, as explained with reference to Fig. 2. The controller 1 16 may utilize the determined voltage to protect the motor 106 from the overvoltage and undervoltage condition. Accordingly, to protect the motor 106 from the overvoltage and the undervoltage condition, the controller 1 16 may determine if the RMS value of the voltage is within the rated voltage range, at block 308.

[0044] If it is determined that the RMS value of the voltage is outside of the rated voltage range, the controller 1 16 may repeat the step at block 306 to determine the RMS value of the voltage based on subsequent samples of voltage. On the other hand, if it is determined that the RMS value of the voltage is within the rated voltage range, the controller 1 16 may determine a mode of operation of the motor 106, at block 310.

[0045] In an example, the pump may be operated in an automatic mode or a manual mode. The automatic mode may be referred as the auto mode. In the auto mode, the pump is to operate within a first time slot. For instance, in the auto mode, the pump is to operate between a given time slot of the day, such as between 10 AM and 1 1 AM. In such a case, the pump and the motor 106 may automatically turn on at the beginning of the time slot and turn off at the end of the time slot. To keep track of time of operation of the motor 106, the motor system 100 may include a clock coupled to the controller 1 16. In some examples, the clock may be in-built with the controller 1 16. Further, the time slot in which the motor 106 is to run may be pre-loaded in the controller 1 16 or the memory, so that the controller 1 16 may operate the motor 106 in the time slot. In the manual mode, the motor 106 is to run whenever the motor 106 and the pump are turned on.

[0046] If the mode is determined to be the auto mode, at block 312, the controller 1 16 may read the time of operation of the motor 106, and at block 314, the controller 1 16 may determine if the read time is within the first time slot. If it is determined that the read time is outside of the first time slot, the controller 1 16 may switch off the relay 1 12, at block 316, since in the auto mode, the motor 106 may operate only in the first time slot. If it is determined that the time of operation of the motor 106 Is within the first time slot, the controller 1 16 may detect underload condition and the overload condition based on the power supplied to the motor 106 to protect the motor 106 from the overload or underload conditions. If, at block 310, it is determined that the mode of operation is manual mode, the controller 1 16 may detect the overload condition and the underload condition.

[0047] To detect the overload condition, or the underload condition, and to subsequently protect the motor 106 upon the detection, at block 318, the controller 1 16 may estimate the power supplied to the motor 106 based on the plurality of samples of the voltage and the plurality of samples of the current. In an example, the controller 1 16 may estimate the power based on the first plurality of samples of the voltage and the first plurality of samples of the current, as explained with reference to Fig. 2.

[0048] Further, at block 320, the controller 1 16 may determine if the power supplied to the motor 106 is within the threshold range, such as between the first power threshold and the second power threshold. If it is determined that the power is outside of the range, i.e., the power being either less than the first power threshold or higher than the second power threshold, the controller 1 16 may switch off the relay 1 12 to turn off the motor 106 at block 316, as explained with reference to block 220 and block 222. On the other hand, if it is determined that the power is within the threshold range, the controller 116 may repeat the step at block 318 to estimate the power based on subsequent samples of the current and subsequent samples of the voltage to be able to protect the motor when the power is higher than the second power threshold or the power is less than the first power threshold.

[0049] Although in the above examples, the motor system 100 is explained with reference to driving a pump, in some examples, the motor system 100 may be coupled to a compressor to drive the compressor.

[0050] The present subject matter prevents the malfunctioning and failure of the motor system caused due to the extreme load conditions, such as an overload condition and an underload condition. Further, by computing the power supplied to the motor and utilizing the computed power to estimate the extreme load condition, the present subject matter detects the extreme loading conditions instantaneously and prevents a time lag between the occurrence of the extreme loading conditions and the detection. The present subject matter eliminates use of separate components, such as the dry run sensor, to detect the underload condition of the motor. The present subject matter facilitates fast, safe, and efficient protection of the motor.

[0051] Although the present subject matter has been described with reference to specific embodiments, this description is not meant to be construed in a limiting sense. Various modifications of the disclosed embodiments, as well as alternate embodiments of the subject matter, will become apparent to persons skilled in the art upon reference to the description of the subject matter.