COMPENSATION OF A VARIABLE DC LINK VOLTAGE WHEN ESTIMATING THE POWER OF A SWITCHED RELUCTANCE MOTOR

Abstract

A control system (200) for a switched reluctance (SR) motor (206), the control system (200) comprising: a direct current source (202); a power converter (204) coupled on its input side to the DC power source (202) and coupled on its output side to the SR motor (206), wherein the power converter (204), which operates primarily as an inverter, is configured to receive DC voltage (DC) from the DC power source (202) and to supply AC current (AC) to the SR motor (206); a user interface configured to enable an operator to specify a desired torque output and generate signals indicative of the desired torque output; a controller (216) communicatively coupled to the SR motor (206), the DC power source (202), the power converter (204), and the user interface, the controller (216) being configured to converting a direct current from the alternating current supplied to the SR motor (206) from the power converter (204); to estimate the actual power output of the SR motor (206) based on at least the DC voltage and the converted DC current; to determine the speed of the SR motor (206); to estimate the actual torque output based on the actual power output and the speed of the SR motor (206); receive the signals indicating the desired torque output from the user interface; compare the actual torque output and the desired torque output to determine the torque deviation; to set the torque output limit based on the determined torque deviation and adjust the speed of the SR motor (206) based on the set torque output limit.

Description

Technical area

[0001] The present disclosure relates to a switched reluctance motor. More specifically, the present disclosure relates to a control system for the switched reluctance motor. background

[0002] An electric powertrain for work machines, such as a tracked tractor, may typically include a prime mover (e.g., an internal combustion engine), a generator coupled to the prime mover, a direct current (DC) power source, and a motor. The direct current (DC) source may be electrically coupled between the generator and the motor to drive one or more ground engaging elements of the machine. A converter, which primarily functions as a rectifier, may be electrically coupled between the generator and the DC power source. The converter, which primarily functions as a rectifier, may be controlled to convert alternating current (AC) to direct current (DC) when the generator is producing electricity, and to convert direct current to alternating current (DC) when the generator is producing electricity.uses electrical power to drive the motor. An inverter, also known as a drive amplifier, may be electrically coupled between the DC power source and the motor. The inverter, which operates primarily as an inverter, may be configured to convert direct current (DC) or DC power from the DC power source to alternating current (AC) or AC power when the generator is using electricity or electrical power to drive the motor, and to convert AC power to DC or AC power to DC power during electrical braking of the motor.

[0003] The motor can be a switched reluctance motor (SR motor). Traditionally, the SR motor is controlled using a table-based control system. However, this type of control cannot compensate for dynamic variations in the system, such as the DC link voltage or the phase currents of the SR motor's phases. This is due to the fact that the control tables are tuned or calculated at a fixed DC link voltage depending on the test bench setup. In practice, if the DC link voltage deviates from this voltage or the actual phase current has drifted from the target phase current, the actual torque generated by the SR motor can deviate significantly from the requested torque.

[0004] To account for DC link voltage fluctuations, control maps developed independently of the test bench setup should include an axis or dimension for the DC link voltage. This requirement increases the required memory space proportional to the number of voltage points considered, and a higher-dimensional interpolation algorithm is required to account for the additional dimension. A higher DC link voltage reduces the reliability and / or accuracy of an SR motor's initial position algorithm. As a result of the lower accuracy of the initial position algorithm, the risk of reduced torque accuracy increases even further. In addition, part-to-part variations that occur during SR motor manufacturing increase the risk of torque accuracy errors.The process of torque tuning is costly and time-consuming, but is currently required for every new design implementation. For an SR motor, where the speed is controlled to a speed target, directly adjusting the torque output based on an algorithm can complicate speed control tuning. Furthermore, setting the torque limit too high can cause damage to mechanical and electrical components. Setting the torque limit too low, on the other hand, will degrade motor performance.

[0005] Consequently, improved means for controlling the SR motor are required.

[0006] From DE 10 2004 039 385 B4 a motor drive control device is known which limits a torque setpoint according to the input voltage and the input current of a power converter driving the motor to the range of the maximum power of the motor.

[0007] Furthermore, EP 1 716632 B1 discloses a control of electrical machines which compensates for differences between an applied DC link voltage and a predetermined DC link voltage by means of an associated correction factor for ignition angles. Brief description

[0008] In one aspect of the present disclosure, a control system for a switched reluctance (SR) motor is provided. The control system includes a DC power source and a power converter coupled to the DC power source on its input side. The power converter is coupled to the SR motor on its output side. The power converter, operating primarily as an inverter, receives DC voltage from the DC power source and supplies alternating current (AC) to the SR motor. The control system includes a user interface that allows an operator to specify a desired torque output. The user interface generates signals indicative of the desired torque output. The control system further includes a controller in communication with the SR motor, the DC power source, the power converter, the speed sensor, and the user interface.The controller determines a direct current by converting the alternating current supplied to the SR motor from the power converter. The controller estimates the actual power output of the SR motor based on at least the DC voltage and the converted DC current. The controller determines the speed of the SR motor. The controller estimates the actual torque output based on the actual power output and the speed of the SR motor. The controller receives signals from the user interface indicating the desired torque output. The controller compares the actual torque output and the desired torque output to determine the torque deviation. In addition, the controller sets a torque output limit based on the torque deviation and adjusts the speed of the SR motor based on the torque output limit.

[0009] In another aspect of the present disclosure, a switched reluctance drive is provided. The switched reluctance drive includes a stator and a rotor configured to rotate within the stator. The switched reluctance drive includes a DC power source and a power converter coupled to the DC power source on its input side. On its output side, the power converter is coupled to the SR motor. The power converter, which operates primarily as an inverter, receives DC voltage from the DC power source and supplies alternating current (AC) to the SR motor. The switched reluctance drive includes a user interface that allows an operator to determine a desired torque output. The user interface generates signals indicative of the desired torque output.The switched reluctance drive also includes a controller in communication with the SR motor, the power converter, the speed sensor, and the user interface. The controller determines a DC current by converting the AC current supplied to the SR motor from the power converter. The controller estimates the actual power output of the SR motor based on at least the DC voltage and the converted DC current. The controller determines the speed of the SR motor. The controller estimates the actual torque output based on the actual power output and the speed of the SR motor. The controller receives signals from the user interface indicating the desired torque output. The controller compares the actual torque output and the desired torque output to determine the torque deviation. The controller also sets a torque output limit based on the torque deviation and adjusts the actual torque output of the SR motor based on the torque output limit.

[0010] In yet another aspect of the present disclosure, a method for controlling a switched reluctance (SR) motor is provided. The method includes determining, by a controller, a direct current (DC) by converting an alternating current (AC). The alternating current is supplied to the SR motor from a power converter. The method includes estimating, by the controller, the actual power output of the SR motor based on at least the converted direct current and a direct voltage. The direct voltage is supplied to the power converter from a direct current source. The method includes determining, by the controller, the speed of the SR motor. The method includes estimating, by the controller, the actual torque output based on the actual power output and the speed of the SR motor. The method includes receiving, by the controller, signals indicative of the desired torque output from the user interface.The method includes comparing the actual torque output and the desired torque output to determine the torque deviation. The method includes setting a torque output limit using the controller. Furthermore, the method includes adjusting the speed of the SR motor based on the torque output limit using the controller. Short description of the drawings Fig. 1 is an exemplary machine, illustrated as a tracked tractor, according to an embodiment of the present disclosure; Fig. 2 is a block diagram showing a control system for the machine of Fig. 1 schematically illustrates an embodiment of the present disclosure; and Fig. 3 is a flowchart showing a method for controlling the machine of Fig. 1 according to an embodiment of the present disclosure. Detailed description

[0011] Where possible, the same reference symbols are used throughout the drawing to designate identical or similar parts. Fig. 1 illustrates an exemplary machine 100. The machine 100 may be a mobile machine that performs work associated with industries such as mining, construction, agriculture, transportation, landscaping, or the like. For example, the machine 100 may be a tracked tractor or a bulldozer, as shown in Fig. 1, may be a motor grader or other commonly known earth-moving machine. While the following detailed description presents an exemplary aspect in connection with a tracked tractor, it should be understood that the description is equally applicable to the application of the present disclosure to other machines.

[0012] As shown, the machine 100 includes an operator's station or cab 102. The cab 102 may include a user interface (not shown) for operating the machine 100. For example, the user interface may be provided along with or may include one or more displays. The user interface may be configured to propel the machine 100 and / or control other machine components. In embodiments, the user interface may be an accelerator pedal or a digital interface that may enable an operator to provide a desired torque command for operation of the machine 100. Additionally, the user interface may include one or more joysticks provided inside the cab 102 and configured to receive input from an operator indicative of a desired movement of the machine 100.The display may communicate information to the operator and may include a keyboard, a touchscreen, or any suitable mechanism for receiving operator inputs to control and / or operate the machine 100 and / or the other machine components.

[0013] The machine 100 further includes an attachment system 104. The attachment system 104 may be adapted to engage, penetrate, or mill a ground surface 106 of a construction site, and may further be adapted to move earth to perform a predetermined task. The construction site may include, for example, a mine site, a landfill, a quarry, a construction site, a golf course, or another type of construction site. Furthermore, the machine 100 includes ground-engaging elements 108 for propelling the machine 100 forwardly or reversely on the ground surface 106. In the illustrated embodiment, the ground-engaging elements 108 are shown as track chains. In some embodiments, the ground-engaging elements 108 may also be implemented as wheels.The desired torque command provided by the operator via the user interface may be a torque required to operate the attachment system 104, a torque required to drive the machine 100 via the ground engaging elements 108, or a combination of the two, based on the needs of the application.

[0014] The machine 100 includes a prime mover 110 that provides power for various purposes, such as driving the machine 100, operating the attachment system 104, etc. The prime mover 110 may be an internal combustion engine, such as a gasoline engine, a diesel engine, or a gas engine. The prime mover 110 supplies power to the attachment system 104 and / or the ground engaging elements 108 via a switched reluctance drive. Various components and operational aspects of the switched reluctance drive are described with the aid of Fig. 2 explained.

[0015] Fig.2 illustrates a control system 200 for the switched reluctance drive of machine 100. Control system 200 includes a DC power source 202 coupled to prime mover 110. Prime mover 110 may supply power to DC power source 202 via a generator (not shown). Prime mover 110 generates mechanical power and supplies the mechanical power to the generator. The generator converts the mechanical power into electrical power and supplies it to DC power source 202. A converter (not shown), primarily operating as a rectifier, may be provided between the generator and DC power source 202 to convert the electrical power from the generator into DC power to supply DC power source 202. Control system 200 further includes an inverter 204. Inverter 204 has an input side and an output side.On its input side, the power converter 204 is coupled to the DC power source 202, so that the power converter 204, which operates primarily as an inverter, receives DC power from the DC power source 202. On its output side, the power converter 204 is coupled to a switched reluctance (SR) motor 206. The power converter 204 receives the DC power from the DC power source 202 and supplies AC power to the SR motor 206.

[0016] The SR motor 206 includes a rotor that rotates within a stator of the SR motor 206. The SR motor 206 is configured to convert electrical energy into mechanical energy (in a motoring mode) or to convert mechanical energy into electrical energy (in a braking mode). The SR motor 206 is operable in the motoring mode to receive electrical energy from the power converter 204 and convert it into mechanical energy. In the braking mode, the SR motor 206 is capable of converting mechanical energy into electrical energy supplied to the power converter 204, thereby decelerating (i.e., slowing down) the speed of the SR motor 206 and consequently the speed of the machine 100. The SR motor 206 may further be coupled to a final drive 208 of the machine 100.The SR motor 206 may be configured to deliver torque to the final drive 208, which torque may be further distributed to the ground engaging elements 108 by the final drive 208 according to the requirements of the application.

[0017] In some embodiments, the SR motor 206 may be provided with torque output limits based on the application requirements. The limits may include, among other things, a maximum torque output and a minimum torque output. The maximum and minimum torque output define a range of torque output that can be provided by the SR motor 206 to the driveline 208. The torque output limits may depend on various factors, including, but not limited to, the operating condition of the SR motor 206, such as the wear condition of the rotor and stator, characteristics of the SR motor 206, such as the number of poles of the rotor, size of the stator and rotor, magnetization curves, etc. In addition, the torque output limit may depend on the application for which the machine 100 is used, such as excavating, grading, etc., machine specifications and the efficiency of the SR motor, as well as operating characteristics of other components of the switched reluctance drive, such as the efficiency of the power converter, the maximum energy storage capacity of the DC power source, etc. Thus, the force or power generated by the prime mover 110 is supplied to the ground engaging elements 108 by means of the switched reluctance drive.

[0018] The control system 200 includes a voltage sensor 210 coupled to the DC power source 202. The voltage sensor 210 measures the DC voltage currently supplied from the DC power source 202 to the power converter 204. The DC voltage supplied from the DC power source 202 to the power converter 204 is also referred to as the intermediate circuit voltage. The voltage sensor 210 can be any type that can be configured to measure the DC voltage currently supplied to the power converter 204 from the DC power source 202. The voltage sensor 210 generates signals indicative of the measured DC voltage. The control system 200 also includes a current sensor 212 coupled to the power converter 204. The current sensor 212 measures the AC current currently supplied to the SR motor 206 from the power converter 204.Current sensor 212 may be any type capable of measuring the AC current currently supplied to SR motor 206 from power converter 204. In some embodiments, SR motor 206 is embodied as a three-phase motor. In such a case, current sensor 212 is electrically coupled to one of the three phases of SR motor 206 to sense the phase current of that phase and output a phase current signal indicative of that phase current.

[0019] Furthermore, the control system 200 includes a speed estimation module 214. The speed estimation module 214 may be a single or multiple microprocessors, a microcontroller, or any other such component that can perform the necessary calculations to estimate the speed of the SR motor 206. The speed estimation module 214 may estimate the speed of the SR motor 206 based on various parameters, such as the characteristics of the SR motor 206, the position of the rotor, etc. In some embodiments, the speed of the SR motor 206 may be determined using a speed sensor coupled to the SR motor 206. The speed sensor may measure the speed of the SR motor 206. In particular, the speed sensor may measure the speed of the rotor within the stator of the SR motor 206.The speed sensor can be any type of speed sensor that can accurately measure the speed of the SR motor 206. The speed sensor can generate signals indicating the measured speed of the SR motor 206.

[0020] Furthermore, the control system 200 includes a controller 216. The controller 216 may be implemented using one or more elements of a processor, a microprocessor, a microcontroller, a digital signal processor (DSP), a field programmable gate array (FPGA), an electronic control module (ECM), an electronic control unit (ECU), or other suitable means to electronically control the functionality of the control system 200. The controller 216 may be configured to operate according to a predetermined algorithm or set of instructions for operating the switched reluctance drive based on the speed and / or position of the rotor relative to the stator and other operating conditions of the electric drive.Such an algorithm or list of instructions may be preprogrammed or contained in memory accessible to and / or located within the controller, as is well known. For example, the controller 216 may determine an initial position of the rotor relative to the stator when the SR motor 206 begins operation. The controller 216 may then control the operation of the SR motor 206 based on the initial position of the rotor. It should be appreciated that the controller 216 may control the operation of the switched reluctance drive based on various parameters, and the example of the initial rotor position in no way limits the scope of the present disclosure.

[0021] The controller 216 is communicatively coupled to the DC power source 202, the power converter 204, and the SR motor 206. The controller 216 is also communicatively coupled to the voltage sensor 210, the current sensor 212, and the speed estimation module 214. The controller 216 receives the signals generated by the voltage sensor 210, which indicate the DC voltage supplied to the power converter 204 from the DC power source 202. The controller 216 receives the signals generated by the current sensor 212, which indicate the AC current supplied to the SR motor 206 from the power converter 204. The controller 216 also receives the speed of the SR motor via the speed estimation module 214. In some embodiments, the controller 216 receives the signals indicative of the speed of the SR motor 206 from the speed sensor.

[0022] After receiving the signals generated by current sensor 212, which indicate the alternating current supplied to SR motor 206 by power converter 204, controller 216 converts the alternating current into a direct current. The conversion of the alternating current into a direct current by controller 216 can be performed based on conventional, well-known methods or algorithms suitable for the application requirements. Furthermore, the present disclosure is by no means limited to the method or algorithm used for the direct current conversion.

[0023] The controller 216 then estimates the actual power output of the SR motor 206 based on the converted DC current and the DC voltage supplied to the power converter 204 from the DC power source 202. The controller 216 receives the signals indicative of the DC voltage from the voltage sensor 210. Because it is in communication with the DC power source 202, the controller 216, in some embodiments, may have information about the state of charge of the DC power source 202 and may determine the DC voltage based on the state of charge. The actual power output may also be thought of as the electrical power supplied to the SR motor 206. The controller 216 may estimate the actual power output by multiplying the converted DC current and the DC voltage. The controller 216 may also store the efficiency of the power converter in associated memory.When estimating the actual power output of the SR motor 206, the controller 216 may, in some embodiments, also consider the efficiency of the power converter. For example, the controller 216 may use the efficiency of the power converter in converting the AC current to DC current. Furthermore, the controller 216 may estimate the actual power output by multiplying the converted DC current, the DC voltage, and the efficiency of the SR motor. The controller 216 may estimate the actual power output by multiplying the reconstructed DC current, the DC voltage, and the efficiency of the power converter.

[0024] After estimating the actual power output, the controller 216 receives the speed of the SR motor 206 from the speed estimation module 214. In some embodiments, the controller 216 may receive signals indicative of the speed of the SR motor 206 via the speed sensor. The controller 216 estimates the actual torque output of the SR motor 206 based on the actual power output and the speed. By dividing the actual power output by the speed of the SR motor 206, the controller 216 may determine the actual torque output. In some embodiments, the controller 216 may store the efficiency of the SR motor in associated memory. The controller 216 may also consider the efficiency of the SR motor when estimating the actual torque output. For example, the controller 216 may estimate the actual torque output by multiplying the actual power output and the efficiency of the SR motor to obtain a value and then dividing the value by the speed of the SR motor 206.

[0025] Furthermore, the controller 216 is in communication with the user interface. The controller 216 can receive signals indicating the desired torque output, which has been set / accurately determined by the operator via the user interface. The controller 216 then compares the actual torque output with the desired torque output. By comparing the actual torque output and the desired torque output, the controller 216 can determine a torque deviation. Based on the torque deviation, the controller 216 sets the torque output limits of the SR motor 206. The controller 216 sets the torque output limits so that the torque output deviation can be minimized, and the SR motor 206 will operate within appropriate torque ranges according to the application requirements. Furthermore, the controller 216 can adjust the torque output of the SR motor 206 based on the set torque output limits.The controller 216 can adjust the torque output to operate the SR motor 206 in an operating state where the torque output of the SR motor 206 is as close as possible to the desired torque output as specified by the operator. In some embodiments, the controller 216 adjusts the speed of the SR motor 206 based on the set torque output limits.

[0026] The controller 216 may adjust the torque output of the SR motor 206 and / or the speed of the SR motor 206 to minimize the torque deviation and operate the switched reluctance drive such that the actual torque output is as close as possible to the desired torque output. To minimize the torque deviation, the controller 216 may use conventional feedback control means, such as proportional-integral-derivative (PID) control, proportional-integral (PI) control, etc. In minimizing the torque deviation, the present disclosure is by no means limited to feedback control means. Industrial applicability

[0027] The present disclosure provides an improved method 300 for controlling the SR motor 206 of the switched reluctance drive for the machine 100. The method 300 includes, at step 302, converting the DC power using the controller 216. The controller 216 converts the DC power based on the AC power supplied to the SR motor 206 from the power converter 204. The controller 216 may use one of the well-known methods and / or algorithms to convert the DC power based on the AC power.

[0028] In step 304 of method 300, the actual power output of the SR motor 206 is estimated. The controller 216 estimates the actual power output based on the converted DC current and the DC voltage supplied to the power converter 204 from the DC power source 202. The controller 216 may be communicatively coupled to the DC power source 202 and may determine the DC voltage based on the state of charge of the DC power source 202. In some embodiments, the controller 216 may receive signals indicative of the DC voltage from the voltage sensor 210 coupled to the DC power source 202. The controller 216 may estimate the actual power output by multiplying the converted DC current and the DC voltage supplied to the power converter (204) from the DC power source (202).In some embodiments, the controller 216 may also consider the efficiency of the power converter and the efficiency of the SR motor when estimating the actual power output. The controller 216 may use the efficiency of the power converter in converting the AC power to DC power. Furthermore, the controller 216 may estimate the actual power output by multiplying the converted DC current, the DC voltage, and the efficiency of the SR motor.

[0029] In step 306 of method 300, the speed of the SR motor 206 is determined. For example, the controller 216 receives the speed of the SR motor 206 using the speed estimation module 214. In some embodiments, the controller 216 may receive the signals indicative of the speed of the SR motor 206 from the speed sensor. In step 308, the method 300 includes estimating the actual torque output. The controller 216 determines the actual torque output based on the actual power output and the speed of the SR motor 206. In some embodiments, the controller 216 determines the actual torque output by dividing the actual power output by the speed of the SR motor 206. In estimating the actual torque output, the controller 216 may, in some embodiments, also consider the efficiency of the SR motor.

[0030] In step 310, method 300 includes receiving signals indicative of the desired torque output from the user interface. Controller 216 receives the signals generated by the user interface indicative of the desired torque output. In some embodiments, the user interface may be the accelerator pedal, the digital interface, or the joystick. In step 312, method 300 includes comparing the actual torque output and the desired torque output. Controller 216 compares the actual torque output and the desired torque output to determine the torque deviation. Controller 216 may include necessary means for comparing the actual torque output and the desired torque output and subsequently determining the torque deviation.

[0031] In step 314, the method 300 includes setting the torque output limit. The torque output limits may depend on various factors, such as, but not limited to, the operating condition of the SR motor 206, characteristics of the SR motor 206, an application such as excavating or trenching, etc., for which the machine 100 is used, machine specifications, the efficiency of the SR motor, and operating characteristics of other components of the switched reluctance drive, etc. The controller 216 sets the torque output limit based on the determined torque deviation and then controls the SR motor 206 based on the set torque limits. In step 316 of the method 300, the speed of the SR motor 206 is set based on the set torque output limit. The controller 216 sets the speed of the SR motor 206 based on the set torque output limit.

[0032] The present disclosure provides an improved method for controlling the SR motor 206 by taking the DC link voltage into account, while simultaneously providing an algorithm for controlling both the torque output and the speed of the SR motor 206. Because the fluctuating DC link voltage is no longer a factor, it is no longer necessary to have an additional axis or dimension for the DC link voltage values ​​in the control algorithms. Furthermore, the present disclosure enables the controller 216 to determine the torque output required to achieve and maintain the target speed of the SR motor 206 according to the requirements of the application. The accuracy of the torque output is accounted for by setting the torque output range according to the required speed of the SR motor 206.Furthermore, the torque output accuracy is maintained regardless of initial position error and / or torque command errors due to varying or high DC link voltage.

[0033] Although aspects of the present disclosure have been particularly shown and described with reference to the foregoing embodiments, it will be understood by those skilled in the art that various other embodiments may be contemplated by modifying the disclosed machines, systems, and methods without departing from the spirit and scope of the disclosure. Such embodiments are understood to be within the scope of the present disclosure as determined by the claims and equivalents thereof.

Claims

[1] A control system (200) for a switched reluctance (SR) motor (206), the control system (200) comprising: a direct current source (202); a power converter (204) coupled on its input side to the DC power source (202) and coupled on its output side to the SR motor (206), wherein the power converter (204), which operates primarily as an inverter, is configured to receive DC voltage (DC) from the DC power source (202) and to supply AC current (AC) to the SR motor (206); a user interface configured to enable an operator to specify a desired torque output and generate signals indicative of the desired torque output; a controller (216) communicatively coupled to the SR motor (206), the DC power source (202), the power converter (204), and the user interface, the controller (216) being configured to converting a direct current from the alternating current supplied to the SR motor (206) from the power converter (204); to estimate the actual power output of the SR motor (206) based on at least the DC voltage and the converted DC current; to determine the speed of the SR motor (206); to estimate the actual torque output based on the actual power output and the speed of the SR motor (206); receive the signals indicating the desired torque output from the user interface; compare the actual torque output and the desired torque output to determine the torque deviation; to set the torque output limit based on the determined torque deviation and adjust the speed of the SR motor (206) based on the set torque output limit. [2] The control system (200) of claim 1, wherein the controller (216) estimates the actual power output based on the efficiency of the power converter, the efficiency of the SR motor (206), the DC voltage, and the DC current. [3] The control system (200) of claim 1, wherein the controller (216) determines the output torque deviation by determining the difference between the actual torque output and the desired torque output. [4] The control system (200) of claim 1, wherein the controller (216) estimates the actual power output by multiplying the DC voltage and the DC current. [5] The control system (200) of claim 1, wherein the controller (216) estimates the actual torque output by dividing the actual power output by the speed of the SR motor (206). [6] The control system (200) of claim 1, wherein the controller (216) determines the speed of the SR motor (206) using at least one of a speed sensor or a speed estimation module (214). [7] Switched reluctance drive, comprising: a switched reluctance (SR) motor (206) having a stator and a rotor adapted to rotate within the stator; a direct current source (202); a power converter (204) coupled on its input side to the DC power source (202) and coupled on its output side to the SR motor (206), wherein the power converter (204), which operates primarily as an inverter, is configured to receive DC voltage (DC) from the DC power source (202) and to supply AC current (AC) to the SR motor (206); a user interface configured to enable an operator to request a desired torque output and generate signals indicative of the desired torque output; a controller (216) communicatively coupled to the SR motor (206), the DC power source (202), the power converter (204), and the user interface, the controller (216) being configured to to reconstruct a direct current from the alternating current supplied to the SR motor (206) by the power converter (204); to estimate the actual power output of the SR motor (206) based on at least the DC voltage and the reconstructed DC current; to determine the speed of the SR motor (206); to estimate the actual torque output based on the actual power output and the speed of the SR motor (206); receive the signals indicating the desired torque output from the user interface; compare the actual torque output and the desired torque output to determine the torque deviation; to set the torque output limit based on the determined torque deviation and to set the actual torque output of the SR motor (206) based on the set torque output limit. [8] A switched reluctance drive according to claim 7, wherein the controller (216) estimates the actual power output based on the efficiency of the power converter, the efficiency of the SR motor (206), the DC voltage and the DC current. [9] A switched reluctance drive according to claim 7, wherein the controller (216) determines the output torque deviation by determining the difference between the actual torque output and the desired torque output. [10] A switched reluctance drive according to claim 7, wherein the controller (216) estimates the actual power output by multiplying the DC voltage and the DC current.

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