阅读说明：本技术 用于可变直流链路电压的开关磁阻电动机功率估计补偿 (Switched reluctance motor power estimation compensation for variable DC link voltage ) 是由 J·L·米勒 E·伊诺雅 J·格迪斯 A·C·克罗斯曼三世 C·E·尼诺-巴伦 T·M·小 于 2018-06-04 设计创作，主要内容包括：一种用于开关磁阻(SR)电动机(206)的控制系统(200)包括直流(DC)电源(202)和逆变器(204)。控制系统(200)包括用户界面,该用户界面配置为使得操作员能够指定期望扭矩输出。控制系统(200)还包括控制器(216),该控制器(216)将由逆变器(204)供应给SR电动机(206)的交流电流(AC)转换为DC电流。控制器(216)基于由DC电源(202)供应给逆变器(204)的DC电压和转换的DC电流来估计由SR电动机(206)产生的实际功率输出。控制器(216)基于SR电动机(206)的实际功率输出和转速来估计实际扭矩输出。控制器(216)比较实际扭矩输出和期望扭矩输出以计算扭矩误差。控制器(216)调节SR电动机(206)的扭矩输出极限和转速。(A control system (200) for a Switched Reluctance (SR) motor (206) includes a Direct Current (DC) power source (202) and an inverter (204). The control system (200) includes a user interface configured to enable an operator to specify a desired torque output. The control system (200) also includes a controller (216), the controller (216) converting Alternating Current (AC) supplied by the inverter (204) to the SR motor (206) to DC current. The controller (216) estimates an actual power output generated by the SR motor (206) based on the DC voltage supplied by the DC power source (202) to the inverter (204) and the converted DC current. The controller (216) estimates an actual torque output based on the actual power output and the rotational speed of the SR motor (206). The controller (216) compares the actual torque output and the desired torque output to calculate a torque error. A controller (216) regulates a torque output limit and a rotational speed of the SR motor (206).)

1. A control system (200) for a switched reluctance motor (206), the control system (200) comprising:

a DC power supply (202);

an inverter (204) coupled to the direct current power source (202) towards an input side of the inverter (204) and to the switched reluctance motor (206) towards an output side of the inverter (204), wherein the inverter (204) is configured to receive a direct current voltage from the direct current power source (202) and to supply an alternating current to the switched reluctance motor (206);

a user interface configured to enable an operator to specify a desired torque output and to generate a signal indicative of the desired torque output;

a controller (216) communicably coupled to the switched reluctance motor (206), the direct current power source (202), the inverter (204), and the user interface, wherein the controller (216) is configured to:

converting alternating current supplied by the inverter (204) to the switched reluctance motor (206) into direct current;

estimating an actual power output generated by the switched reluctance motor (206) based on at least the direct current voltage and the converted direct current;

determining a rotational speed of the switched reluctance motor (206);

estimating an actual torque output based on the actual power output and the rotational speed of the switched reluctance motor (206);

receiving a signal from the user interface indicative of the desired torque output;

comparing the actual torque output and the desired torque output to calculate a torque error;

adjusting a torque output limit based on the calculated torque error, an

Adjusting the rotational speed of the switched reluctance motor (206) based on the adjusted torque output limit.

2. The control system (200) of claim 1, wherein the controller (216) estimates the actual power output based on inverter efficiency, switched reluctance motor efficiency, direct voltage, and direct current.

3. The control system (200) of claim 1, wherein the controller (216) calculates an output torque error by calculating a 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 a direct current voltage by a direct 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 a rotational speed of the switched reluctance motor (206).

6. The control system (200) of claim 1, wherein the controller (216) determines the rotational speed of the switched reluctance motor (206) via at least one of a speed sensor or a speed estimation module (214).

7. A switched reluctance motor speed regulation system comprising:

a switched reluctance motor (206) having a stator and a rotor configured to rotate within the stator;

a DC power supply (202);

an inverter (204) coupled to the direct current power source (202) towards an input side of the inverter (204) and to the switched reluctance motor (206) towards an output side of the inverter (204), wherein the inverter (204) is configured to receive a direct current voltage from the direct current power source (202) and to supply an alternating current to the switched reluctance motor (206);

a user interface configured to enable an operator to request a desired torque output and to generate a signal indicative of the desired torque output;

a controller (216) communicably coupled to the switched reluctance motor (206), the direct current power source (202), the inverter (204), and the user interface, wherein the controller (216) is configured to:

reconstructing the alternating current supplied by the inverter (204) to the switched reluctance motor (206) as a direct current;

estimating an actual power output produced by the switched reluctance motor (206) based on at least the direct current voltage and the reconstructed direct current;

determining a rotational speed of the switched reluctance motor (206);

estimating an actual torque output based on the actual power output and the rotational speed of the switched reluctance motor (206);

receiving a signal from the user interface indicative of the desired torque output;

comparing the actual torque output and the desired torque output to calculate a torque error;

adjusting a torque output limit based on the calculated torque error; and

adjusting the actual torque output of the switched reluctance motor (206) based on the adjusted torque output limit.

8. The switched reluctance motor speed regulation system of claim 7, wherein the controller (216) estimates the actual power output based on inverter efficiency, switched reluctance motor efficiency, direct voltage, and direct current.

9. The switched reluctance motor speed regulation system of claim 7, wherein the controller (216) calculates an output torque error by calculating a difference between the actual torque output and the desired torque output.

10. The switched reluctance motor speed regulation system of claim 7, wherein the controller (216) estimates the actual power output by multiplying a direct current voltage by a direct current.

Technical Field

The present invention relates to a switched reluctance motor. More particularly, the present invention relates to a control system for a switched reluctance motor.

Background

An electric drive system for a work machine, such as a track-type tractor, may generally include an engine (e.g., an internal combustion engine), a generator coupled to the engine, a Direct Current (DC) power source, and an electric motor. The DC power source may be electrically coupled between the generator and the motor to drive one or more ground elements of the machine. The converter may be electrically coupled between the generator and the DC power source. The converter may be controlled to convert Alternating Current (AC) power to DC power when the generator generates electricity, and to convert the DC power to AC power when the generator drives the motor with electric power. The inverter may be electrically coupled between the DC power source and the motor. The inverter may be configured to convert DC power from the DC power source into AC power when the generator drives the motor with electric power, and to convert the AC power into DC power during electric braking of the motor.

The motor may be a Switched Reluctance (SR) motor. Conventionally, an SR motor is controlled using open loop table-based control. However, this type of control cannot compensate for dynamic changes in the system, such as the DC link voltage or phase current of the phases of the SR motor. This is due to the fact that: the control table is tuned or calculated according to the test bench settings at a fixed DC link voltage. In practice, if the DC link voltage deviates from this voltage, or the actual phase current has deviated from the commanded phase current, the actual torque produced by the SR motor may deviate substantially from the requested torque.

To account for variations in DC link voltage, a control chart developed off-line should include an axis for the DC link voltage. In addition to requiring higher dimensional interpolation algorithms to account for the extra dimension, this requirement also increases the required storage space at a rate proportional to the number of voltage points considered. The higher DC link voltage reduces the reliability and/or accuracy of the initial position algorithm of the SR motor. The risk of lower torque accuracy is further increased due to the lower accuracy of the initial position algorithm. Moreover, part-to-part variations in SR motor manufacturing increase the risk of torque accuracy errors. The torque tuning process is expensive and time consuming, but is currently required each time a new design is implemented. On SR motors where speed is controlled to a speed target, adjusting the torque output directly based on an algorithm may make it difficult to tune the speed control. Furthermore, if the torque limit is set too high, damage to mechanical and electrical components may occur. On the other hand, if the torque limit is set too low, the motor performance is degraded

Accordingly, there is a need for an improved control arrangement for an SR motor.

Disclosure of Invention

In one aspect of the present invention, a control system for a Switched Reluctance (SR) motor is provided. The control system includes a Direct Current (DC) power source and an inverter coupled to the DC power source at an input side of the inverter. The inverter is coupled to the SR motor at an output side of the inverter. The inverter receives a DC voltage from a DC power source and supplies an Alternating Current (AC) current to the SR motor. The control system includes a user interface that enables an operator to specify a desired torque output. The user interface generates a signal indicative of a desired torque output. The control system also includes a controller in communication with the SR motor, the DC power source, the inverter, the speed sensor, and the user interface. The controller determines the DC current by converting the AC current supplied to the SR motor by the inverter. The controller estimates an actual power output generated by the SR motor based at least on the DC voltage and the converted DC current. The controller determines a rotational speed of the SR motor. The controller estimates an actual torque output based on the actual power output and speed of the SR motor. The controller receives a signal from the user interface indicative of a desired torque output. The controller compares the actual torque output to the desired torque output to calculate a torque error. Further, the controller adjusts a torque output limit based on the torque error and adjusts a rotational speed of the SR motor based on the torque output limit.

In another aspect of the invention, a switched reluctance motor governor system is provided. The switched reluctance motor speed regulation system includes a stator and a rotor configured to rotate within the stator. A switched reluctance motor speed control system includes a Direct Current (DC) power source and an inverter coupled to the DC power source toward an input side of the inverter. The inverter is coupled to the SR motor toward an output side of the inverter. The inverter receives a DC voltage from a DC power source and supplies an Alternating Current (AC) current to the SR motor. The switched reluctance motor speed control system includes a user interface that enables an operator to provide a desired torque output. The user interface generates a signal indicative of a desired torque output. The switched reluctance motor speed regulation system also includes a controller in communication with the SR motor, the inverter, the speed sensor, and the user interface. The controller determines the DC current by converting the AC current supplied to the SR motor by the inverter. The controller estimates an actual power output generated by the SR motor based at least on the DC voltage and the converted DC current. The controller determines a rotational speed of the SR motor. The controller estimates an actual torque output based on the actual power output and the rotational speed of the SR motor. The controller receives a signal from the user interface indicative of a desired torque output. The controller compares the actual torque output to the desired torque output to calculate a torque error. Further, the controller adjusts a torque output limit based on the torque error and adjusts an actual torque output of the SR motor based on the torque output limit.

In yet another aspect of the present invention, a method of controlling a Switched Reluctance (SR) motor is provided. The method includes determining a Direct Current (DC) current by converting an Alternating Current (AC) current by a controller. The AC current is supplied to the SR motor by an inverter. The method includes estimating, by the controller, an actual power output generated by the SR motor based at least on the converted DC current and the DC voltage. The DC voltage is supplied to the inverter by a DC power source. The method includes determining, by a controller, a rotational speed of the SR motor. The method includes estimating, by a controller, an actual torque output based on an actual power output and a rotational speed of the SR motor. The method includes receiving, by the controller, a signal from the user interface indicative of a desired torque output. The method includes comparing, by the controller, the actual torque output and the desired torque output to calculate a torque error. The method includes adjusting, by the controller, the torque output limit. The method also includes adjusting, by the controller, a rotational speed of the SR motor based on the torque output limit.

Drawings

FIG. 1 is an exemplary machine, shown as a track type tractor, according to an embodiment of the present disclosure;

FIG. 2 is a block diagram that schematically represents a control system for the machine of FIG. 1, in accordance with an embodiment of the present disclosure; and is

FIG. 3 is a flow chart illustrating a method of controlling the machine of FIG. 1, in accordance with an embodiment of the present invention.

Detailed Description

Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts. Fig. 1 illustrates an exemplary machine 100. Machine 100 may be a mobile machine that performs operations associated with an industry such as mining, construction, farming, transportation, landscaping, and the like. For example, machine 100 may be a track type tractor or a dozer as shown in FIG. 1, a motor grader, or any other earth moving machine known in the art. While the following detailed description describes exemplary aspects associated with a track-type tractor, it should be understood that the description is equally applicable to use of the invention in other machines.

As shown, the machine 100 includes an operator station or cab 102. The cab 102 may include a user interface (not shown) for operating the machine 100. The user interface may be provided with or may include, for example, one or more displays. The user interface may be configured to propel machine 100 and/or control other machine components. In some embodiments, the user interface may be an accelerator pedal or a digital interface that enables an operator to provide a desired torque command to operate the machine 100. The user interface may also include one or more joysticks disposed within the cab 102 and adapted to receive input from an operator indicative of a desired movement of the machine 100. The display may convey information to an operator and may include a keyboard, a touch screen, or any suitable mechanism for receiving input from an operator to control and/or operate machine 100 and/or other machine components.

The machine 100 also includes an implementation system 104. Fulfillment system 104 may be adapted to engage, penetrate, or cut ground 106 of a worksite, and may also be adapted to move soil to accomplish a predetermined task. The worksite may include, for example, a mine site, a landfill, a quarry, a construction site, a golf course, or any other type of worksite. The machine 100 also includes ground engaging members 108 for propelling the machine 100 in a forward or rearward direction over the ground 106. In the illustrated embodiment, the ground engaging members 108 are shown as continuous tracks. In some embodiments, ground engaging members 108 may also be implemented as wheels. The desired torque command provided by the operator via the user interface may be a desired torque for operating implement system 104, a desired torque for propelling machine 100 via ground engaging members 108, or a combination of both based on application requirements.

The machine 100 includes an engine 110 for providing power for various purposes, such as propelling the machine 100, operating the implement system 104, and the like. The engine 110 may be an internal combustion engine, such as a gasoline engine, a diesel engine, or a gas powered engine. The motor 110 provides power to the implement system 104 and/or the ground engaging elements 108 through a switched reluctance motor governor system. The various components and operational aspects of the switched reluctance motor governor system are explained with the aid of fig. 2.

Fig. 2 illustrates a control system 200 for a switched reluctance motor governor system for the machine 100. The control system 200 includes a DC power source 202 that may be coupled to the engine 110. The engine 110 may supply power to the DC power source 202 via a generator (not shown). The engine 110 generates mechanical power and supplies the mechanical power to the generator. The generator converts the mechanical power to electrical power and supplies the electrical power to the DC power source 202. A converter (not shown) may be provided between the generator and the DC power source 202 for converting power from the generator to DC power for supply to the DC power source 202. Control system 200 also includes an inverter 204. The inverter 204 has an input side and an output side. The inverter 204 is coupled to the DC power source 202 toward an input side of the inverter 204 such that the inverter 204 receives DC power from the DC power source 202. The inverter 204 is coupled to a Switched Reluctance (SR) motor 206 toward an output side of the inverter 204. The inverter 204 receives DC power from the DC power source 202 and supplies AC power to the SR motor 206.

The SR motor 206 includes a rotor that rotates inside a stator of the SR motor 206. The SR motor 206 is configured to convert electrical energy to mechanical energy (in a motoring mode) or mechanical energy to electrical energy (in a braking mode). In the motoring mode, the SR motor 206 is operable to receive electrical energy from the inverter 204 and convert it to mechanical energy. In the braking mode, the SR motor 206 may be operable to convert mechanical energy into electrical energy for supply to the inverter 204 to brake (i.e., slow) the rotational speed of the SR motor 206 and, thus, the speed of the machine 100. The SR motor 206 may be further coupled to a final drive 208 of the machine 100. The SR motor 206 may be configured to provide a torque output to the final drive 208, which may be further distributed to the ground engaging elements 108 through the final drive 208, depending on application requirements.

In some embodiments, the SR motor 206 can be provided with a torque output limit based on the application requirements. The limits may include a maximum torque output value and a minimum torque output value. The maximum and minimum torque output values define a range of torque outputs that may be provided by the SR motor 206 to the final drive 208. The torque output limit may depend on various factors such as, but not limited to, operating conditions of the SR motor 206, such as wear states of the rotor and stator, inherent characteristics of the SR motor 206, such as the number of poles of the rotor, dimensions of the stator and rotor, magnetization curves, and the like. The torque output limit may also depend on the application for which the machine 100 is used, such as excavation, classification, etc., machine specifications and SR motor efficiency, as well as operating characteristics of other components of the switched reluctance motor governor system, such as inverter efficiency, maximum energy storage capacity of the DC power source, etc. In this way, power generated by the motor 110 is provided to the ground engaging elements 108 through the switched reluctance motor speed regulation system.

The control system 200 includes a voltage sensor 210 coupled to the DC power source 202. The voltage sensor 210 measures the DC voltage provided by the DC power source 202 to the inverter 204. The DC voltage provided by the DC power source 202 to the inverter 204 may also be referred to as a DC link voltage. The voltage sensor 210 may be any type of voltage sensor that can be configured to measure the DC voltage supplied by the DC power source 202 to the inverter 204. The voltage sensor 210 generates a signal indicative of the measured DC voltage. Control system 200 also includes a current sensor 212 coupled to inverter 204. The current sensor 212 measures the AC current supplied by the inverter 204 to the SR motor 206. The current sensor 212 may be any type of current sensor capable of measuring the AC current supplied by the inverter 204 to the SR motor 206. In some embodiments, the SR motor 206 is implemented as a three-phase motor. In this case, the current sensor 212 is electrically coupled to one of the three phases of the SR motor 206 to sense a phase current of the phase and output a phase current signal indicative thereof.

The control system 200 also includes a speed estimation module 214. The speed estimation module 214 may be a single or multiple microprocessors, or microcontrollers, or any other such type of component that can perform the necessary calculations to estimate the rotational speed of the SR motor 206. The speed estimation module 214 may estimate the rotational speed of the SR motor 206 based on various parameters, such as the inherent characteristics of the SR motor 206, the position of the rotor, and so forth. In some embodiments, the rotational speed of the SR motor 206 may be determined by a speed sensor coupled to the SR motor 206. The speed sensor may measure the rotational speed of the SR motor 206. More specifically, the speed sensor may measure the rotational speed of the rotor within the stator of the SR motor 206. The speed sensor may be any type of speed sensor capable of accurately measuring the rotational speed of the SR motor 206. The speed sensor may generate a signal indicative of the measured rotational speed of the SR motor 206.

The control system 200 also includes a controller 216. The controller 216 may be implemented using one or more of a processor, microprocessor, microcontroller, Digital Signal Processor (DSP), Field Programmable Gate Array (FPGA), Electronic Control Module (ECM), Electronic Control Unit (ECU), or any other suitable means for electronically controlling the functions of the control system 200. The controller 216 may be configured to operate in accordance with a predetermined algorithm or set of instructions for operating the switched reluctance motor speed control system based on the rotational speed and/or position of the rotor relative to the stator and other operating characteristics of the electric drive. Such algorithms or sets of instructions may be preprogrammed or incorporated into a memory accessible to and/or disposed within the controller 216, as is well known in the art. For example, when the SR motor 206 begins operation, the controller 216 can determine an initial position of the rotor relative to the stator. The controller 216 may then control operation of the SR motor 206 based on the initial rotor position. It should be appreciated that the controller 216 may control operation of the switched reluctance motor speed regulation system based on various parameters, and that the example of an initial rotor position does not limit the scope of the present invention in any way.

The controller 216 is communicatively coupled to the DC power source 202, the inverter 204, and the SR motor 206. The controller 216 is also in communication with the voltage sensor 210, the current sensor 212, and the speed estimation module 214. The controller 216 receives a signal generated by the voltage sensor 210 indicative of the DC voltage provided by the DC power source 202 to the inverter 204. The controller 216 receives a signal generated by the current sensor 212 indicative of the AC current supplied by the inverter 204 to the SR motor 206. The controller 216 also receives the rotational speed of the SR motor via the speed estimation module 214. In some embodiments, the controller 216 receives a signal from a speed sensor indicative of the rotational speed of the SR motor 206.

Upon receiving a signal generated by the current sensor 212 indicative of the AC current supplied by the inverter 204 to the SR motor 206, the controller 216 converts the AC current to a DC current. The controller 216 may convert the AC current to DC current based on any conventional method or algorithm known in the art that may be appropriate depending on the application requirements. Furthermore, the invention is not in any way limited to a method or algorithm for DC current conversion.

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 by the DC power source 202 to the inverter 204. The controller 216 receives a signal indicative of the DC voltage from the voltage sensor 210. In some embodiments, when the controller 216 is in communication with the DC power source 202, the controller 216 may have information about the state of charge of the DC power source 202, and the controller 216 may determine the DC voltage based on the state of charge. The actual power output may also be interpreted 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 inverter efficiency in an associated memory. In some embodiments, the controller 216 may also consider the inverter efficiency while estimating the actual power output of the SR motor 206. For example, the controller 216 may use the inverter efficiency while converting AC current to DC current. Further, the controller 216 may estimate the actual power output by multiplying the converted DC current, the DC voltage, and the SR motor efficiency. The controller 216 may estimate the actual power output by multiplying the reconstructed DC current, the DC voltage, and the inverter efficiency.

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

In addition, the controller 216 is also in communication with the user interface. The controller 216 may receive a signal indicative of a desired torque output specified/identified by an operator using a user interface. The controller 216 then compares the actual torque output to the desired torque output. The controller 216 may calculate a torque error based on a comparison of the actual torque output and the desired torque output. The controller 216 adjusts the torque output limit of the SR motor 206 based on the torque error. The controller 216 adjusts the torque output limit so that the torque output error can be minimized and the SR motor 206 operates within the appropriate torque range as required by the application. Further, the controller 216 may adjust the torque output of the SR motor 206 based on the adjusted torque output limit. The controller 216 can adjust the torque output such that the SR motor 206 operates under operating conditions in which the torque output of the SR motor 206 is as close as possible to the desired torque output specified by the operator. In some embodiments, the controller 216 adjusts the speed of the SR motor 206 based on the adjusted torque output limit.

The controller 216 may adjust the torque output of the SR motor 206 and/or the rotational speed of the SR motor 206 to minimize torque errors and operate the switched reluctance motor speed regulation system to produce an actual torque output as close as possible to the desired torque output. The controller 216 may use any conventional feedback control means to minimize the torque error, such as Proportional Integral Derivative (PID) control, Proportional Integral (PI) control, and the like. The present invention is not in any way limited to a feedback control arrangement that minimizes torque error.

Industrial applicability

The present invention provides an improved method 300 for controlling the SR motor 206 of a switched reluctance motor governor system for a machine 100. The method 300 includes converting, by the controller 216, the DC current at step 302. The controller 216 converts the DC current based on the AC current supplied to the SR motor 206 by the inverter 204. The controller 216 may use any method and/or algorithm known in the art to convert the DC current based on the AC current.

The method 300 estimates the actual power output generated by the SR motor 206 at step 304. The controller 216 estimates the actual power output based on the converted DC current and the DC voltage supplied by the DC power source 202 to the inverter 204. The controller 216 can be communicatively coupled with the DC power source 202 and can determine the DC voltage based on a state of charge of the DC power source 202. In some embodiments, the controller 216 may receive a signal 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 by the DC power source 202 to the inverter 204. In some embodiments, the controller 216 may also consider the inverter efficiency and the SR motor efficiency while estimating the actual power output. The controller 216 may use the inverter efficiency while converting the AC current to the DC current. Further, the controller 216 may estimate the actual power output by multiplying the converted DC current, the DC voltage, and the SR motor efficiency.

The method 300 determines the rotational speed of the SR motor 206 at step 306. For example, the controller 216 receives the rotational speed of the SR motor 206 via the speed estimation module 214. In some embodiments, the controller 216 may receive a signal from a speed sensor indicative of the rotational speed of the SR motor 206. The method 300 includes estimating an actual torque output at step 308. The controller 216 determines an actual torque output based on the actual power output and the rotational 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 rotational speed of the SR motor 206. In some embodiments, the controller 216 may also consider SR motor efficiency while estimating the actual torque output.

The method 300 includes receiving a signal from a user interface indicative of a desired torque output at step 310. The controller 216 receives a signal generated by the user interface indicative of a desired torque output. In some embodiments, the user interface may be an accelerator pedal, a digital interface, or a joystick. The method 300 includes comparing the actual torque output to the desired torque output at step 312. The controller 216 compares the actual torque output to the desired torque output to calculate a torque error. The controller 216 may include the required devices for comparing the actual torque output to the desired torque output and subsequently calculating the torque error.

The method 300 includes adjusting the torque output limit at step 314. The torque output limit may depend on various factors such as, but not limited to, the operating conditions of the SR motor 206, the inherent characteristics of the SR motor 206, the application for which the machine 100 is used (e.g., digging or trenching, etc.), the machine specifications, the SR motor efficiency, and the operating characteristics of other components of the switched reluctance motor governor system, etc. The controller 216 adjusts the torque output limit based on the calculated torque error and then controls the SR motor 206 based on the adjusted torque limit. The method 300 adjusts the speed of the SR motor 206 based on the adjusted torque output limit at step 316. The controller 216 adjusts the speed of the SR motor 206 based on the adjusted torque output limit.

The present invention provides an improved method of controlling the SR motor 206 by taking into account the DC link voltage while providing an algorithm for controlling the torque output and speed of the SR motor 206. Since the varying DC-link voltage is no longer of interest, there is no need to have an additional axis in the control algorithm for the DC-link voltage value. Further, the present invention allows the controller 216 to determine a desired torque output in order to achieve and maintain the target speed of the SR motor 206 depending on the application requirements. The accuracy of the torque output is illustrated by adjusting the torque output range according to the desired speed of the SR motor 206. Further, the accuracy of the torque output is maintained despite initial position errors and/or torque command errors due to variable or high DC link voltages.

While aspects of the present invention have been particularly shown and described with reference to the foregoing embodiments, it will be understood by those skilled in the art that various additional embodiments may be devised by modifying the disclosed machines, systems, and methods without departing from the spirit and scope of the disclosure. Such embodiments are to be understood as falling within the scope of the present invention as determined based on the claims and any equivalents thereof.