A stand-alone decoupled motor simulation device

Abstract

The application provides an independent decoupling motor simulation device, comprising: a power hardware module for generating electrical stress of a to-be-tested electric drive system; and an electrical stress control module connected with the power hardware module, for controlling the motor simulator and providing signals for the to-be-tested electric drive system. The control reference value of the motor simulation device is generated by using signals easily obtained by itself, a target motor model and a model of a port filter, and the AC voltage / current is reproduced at the AC test port through closed-loop / open-loop control, without the need of signal transmission or voltage sampling on the electric drive side. The application can realize decoupling with the to-be-tested electric drive converter, is independent of the voltage sampling accuracy of the to-be-tested electric drive converter port and the signal transmission of the electric drive system, and realizes plug-and-play of the motor simulation device.

Description

Technical Field

[0001] This invention relates to the field of power electronics technology, and more specifically, to an independently decoupled motor simulation device. Background Technology

[0002] With the development of power electronics and motor technologies, motors and electric drive systems have been widely used in industry and electric drive fields. The power rating and power density of power electronic converters in electric drive systems are constantly increasing, and their operating conditions are becoming increasingly complex. Before being put into use, electric drive systems often require a series of functional and reliability tests and verifications. Motor simulation devices are becoming the mainstream testing method for functional and reliability testing of electric drive systems.

[0003] Currently, the most typical motor simulators often use a power electronic converter or power amplifier to reproduce the voltage and current of the electric drive system under test under actual operating conditions. This type of motor simulation device has the following limitations:

[0004] 1. Narrow applicability. The port voltage of the electric drive system under test is often a pulse wave, requiring a low-pass voltage filter to filter the voltage. The cutoff frequency of the low-pass voltage filter limits the switching frequency range of the electric drive system under test.

[0005] 2. Low accuracy and stability. Low-pass voltage filters are often second-order filters, which have obvious resonance peaks. These resonance peaks lead to low accuracy and stability in motor simulation devices.

[0006] The search revealed:

[0007] Chinese invention patent application CN113411032A, entitled "Simulation System and Method for Full-Bandwidth Electric Drive System Operating Conditions Based on Voltage Signal Transmission," employs a three-phase DC / AC converter on the drive side to simulate the port voltage of the motor drive at the circuit level; it also employs a three-phase DC / AC converter on the motor side to simulate the current response of the motor at the circuit level; it uses an electric drive speed controller to describe the electrical behavior characteristics of the drive side; and it transmits the voltage modulation signal of the drive-side converter to the electric drive operating condition simulation mathematical model module through a voltage signal transmission module and a ripple suppression passive impedance network module to describe the electrical and mechanical behavior characteristics of the target motor; finally, it employs a full-bandwidth current control module to control the current response of the target motor across the entire frequency band. Compared with this application, this method has the following technical problems and differences:

[0008] 1. This method uses modulation signal transmission to bypass the voltage low-pass filter, which requires the driver-side converter to transmit the voltage modulation signal to the analog-side converter, and it does not have plug-and-play capability.

[0009] 2. This method uses an open-loop control strategy, and the error between the model value and the actual value of the passive impedance network will lead to inaccurate AC test port voltage. Summary of the Invention

[0010] In view of the shortcomings of the prior art, the purpose of this invention is to provide an independently decoupled motor simulation device.

[0011] According to one aspect of the present invention, an independently decoupled motor simulation device is provided, comprising:

[0012] A power hardware module is used to generate the electrical characteristics of the electric drive system under test. The power hardware module includes a motor simulator, an impedance network B, and an impedance network C. The AC terminal of the motor simulator is connected to the AC test port through the impedance network B and then connected to the electric drive system under test. The DC terminal of the motor simulator is connected to the DC power supply port through the impedance network C.

[0013] An electrical stress control module, connected to the power hardware module, is used to control the motor simulator and provide mechanical characteristic signals to the electric drive system under test. The electrical stress control module includes a motor simulator controller, a target model group, and a signal generator. Based on the readily available signals from the motor simulator, a control reference quantity for the motor simulator is generated through the target model group. The motor simulator controller controls the motor simulator to reproduce the electrical characteristics of the target motor in the electric drive system under test at the AC test port. The signal generator reproduces the mechanical characteristics of the target motor at the signal port.

[0014] Preferably, the motor simulator includes a power electronic converter and a resistor network A, wherein the external terminal of the power electronic converter is a DC terminal, and the external terminal of the resistor network A is an AC terminal; wherein:

[0015] The power electronic converter adopts any DC / AC topology or power semiconductor device to reproduce the port voltage and current characteristics of the converter under test in the electric drive system under test.

[0016] The resistive impedance network A is used for filtering, and it can be a current-mode filter or a voltage-mode filter of any structure.

[0017] Preferably, the impedance network B is located at the connection between the AC test port and the power electronic converter to block the common-mode current in the AC bus.

[0018] The impedance network C is disposed between the power electronic converter and the DC power supply port to block the common-mode current ripple of the DC bus.

[0019] Preferably, the resistive impedance network adopts one or more of the following:

[0020] The impedance network B uses an AC common-mode inductor;

[0021] The impedance network B uses a transformer; wherein, the side of the transformer connected to the AC test port adopts a Δ connection, and the side of the transformer connected to the AC terminal adopts a Δ or Y connection.

[0022] The impedance network C uses a DC common-mode inductor.

[0023] Preferably, the target model group uses readily available signals from the motor simulator to generate controller reference quantities for the motor simulator; the readily available signals include the modulation signal of the motor simulator, the AC test port current signal, and the converter output current signal of the motor simulator; the control reference quantities include the AC test port voltage reference quantity, the AC test port current reference quantity, the signal generator speed reference quantity, and the signal generator angle reference quantity; the motor simulator controller, based on the control reference quantities generated by the target model group, uses a current closed-loop / open-loop or voltage closed-loop / open-loop control method to control and restore the electrical characteristics of the electric drive system under test;

[0024] The signal generator is connected to the motor simulator controller and is used to generate the mechanical characteristics required for the control of the electric drive system under test, so as to achieve decoupling between the motor simulator controller and the controller of the electric drive system under test.

[0025] Preferably, when the signal readily available to the motor simulator is the modulation signal e of the analog converter, the target model group includes: target motor model G. m (s), resistive network model G f (s), the output of the target model group is the AC test port current reference quantity i ref And satisfy:

[0026]

[0027] Preferably, when the signal readily available from the motor simulator is the AC test port current signal i s At that time, the target model group includes: target motor model G m (s), resistive network model G f (s), where the output of the target model group is the analog converter modulation signal e, and satisfies:

[0028]

[0029] Preferably, when the signal readily available from the motor simulator is the AC test port current signal is At that time, the target model group includes: target motor model G m (s), the output of the target model group is the AC test port voltage reference u. ref :

[0030]

[0031] Preferably, the reference value of the signal generator speed is obtained by calculating or sampling the current value using the following mathematical formula:

[0032]

[0033]

[0034] Among them, T e p represents the electromagnetic torque of the target motor. n ψ is the number of pole pairs per phase of the motor. f L is the flux linkage amplitude of the permanent magnet in the motor. d L q T represents the equivalent inductance values ​​of the motor stator along the d and q axes. load Where ωm is the load torque, J is the equivalent moment of inertia of the motor, ωm is the mechanical angular frequency of the motor, and F is the viscous friction coefficient of the motor.

[0035] The angle reference value of the signal generator is obtained by integrating the rotational speed reference value of the signal generator.

[0036] Preferably, the motor simulator controller includes a controller and a pulse width modulator; wherein:

[0037] The controller is used to receive the control reference quantity output by the target model group, and generate the modulation signal of the motor simulator converter by means of current closed-loop / open-loop control, voltage single closed-loop control, voltage double closed-loop control or voltage open-loop control.

[0038] The pulse width modulator output controls the switching sequence of the motor simulator, causing the AC test port to generate the electrical characteristics of the target motor.

[0039] Compared with the prior art, the present invention has at least one of the following beneficial effects:

[0040] Traditional LCR low-pass filters suffer from excessive damping, leading to deviations in the amplitude and phase of the sampled signal from the actual values. This results in inaccuracies in system reference calculations and control. Conversely, insufficient damping can reduce amplitude and phase deviations but introduces resonance peaks, causing system resonance. The independently decoupled motor simulation device in this invention eliminates the need for a voltage low-pass filter, ensuring the accuracy and stability of the motor simulation device.

[0041] Traditional LCR low-pass voltage filters have a fixed cutoff frequency, typically 1 / 10 of the switching frequency, making them unsuitable for converters under test with different switching frequencies. The independently decoupled motor simulation device in this invention does not require sampling the converter's port voltage. It uses a current signal that can be sampled without a low-pass filter or a modulation signal calculated in the controller. Therefore, it is not affected by the switching frequency and has a wider range of applications.

[0042] Existing technologies require controller communication to transmit voltage, current, and speed between the motor simulator and the electric drive system under test, thus lacking plug-and-play functionality. In contrast, the independently decoupled motor simulation device in this invention obtains the current signal directly through current sampling, calculates the voltage signal directly from the modulation signal of the motor simulator, and generates the speed signal through a signal generator. It can operate normally without any communication methods that do not exist in the actual electric drive system, thus achieving plug-and-play functionality. Attached Figure Description

[0043] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0044] Figure 1 This is a schematic diagram of an independently decoupled motor simulation device in one embodiment of the present invention;

[0045] Figure 2 This is a schematic diagram of the topology of a three-phase DC / AC power electronic converter based on IGBT in a preferred embodiment of the present invention.

[0046] Figure 3 This is a schematic diagram of the topology of a passive resistive impedance network A in a preferred embodiment of the present invention;

[0047] Figure 4 This is a schematic diagram of the topology of a passive resistive impedance network B in a preferred embodiment of the present invention;

[0048] Figure 5 This is a schematic diagram of the topology of a passive resistive impedance network C in a preferred embodiment of the present invention;

[0049] Figure 6 This is a schematic diagram of the controller control loop in a preferred embodiment of the present invention;

[0050] Figure 7 This is a schematic diagram of the target model group in a preferred embodiment of the present invention. Detailed Implementation

[0051] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention. These all fall within the scope of protection of the present invention.

[0052] See Figure 1 The present invention provides an embodiment of an independently decoupled motor simulation device, comprising a power hardware module and an electrical stress control module.

[0053] The power hardware module is used to generate electrical stress in the electric drive system under test. The power hardware module includes a motor simulator, impedance network B, and impedance network C. The AC terminal of the motor simulator is connected to the AC test port via impedance network B and then to the electric drive system under test; the DC terminal of the motor simulator is connected to the DC power supply port via impedance network C.

[0054] The electrical stress control module, connected to the power hardware module, is used to control the motor simulator and provide signals to the electric drive system under test. The electrical stress control module includes a motor simulator controller, a target model group, and a signal generator. Based on the readily available signals from the motor simulator, it generates control reference quantities for the motor simulator through the target model group. The motor simulator controller then controls the motor simulator to reproduce the electrical characteristics of the target motor at the AC test port, and the signal generator reproduces the mechanical characteristics of the target motor at the signal port.

[0055] Among them, electrical characteristics are the electrical stresses that the system experiences during actual operation, generated by the power hardware module at the test point. Electrical characteristics include voltage and current; mechanical characteristics mainly include speed and angle.

[0056] This embodiment achieves decoupling from the converter in the electric drive system under test, without relying on the port voltage sampling accuracy of the converter under test and the signal transmission of the electric drive system, thus realizing plug-and-play functionality of the motor simulation device.

[0057] In a preferred embodiment of the present invention, the motor simulator includes a power electronic converter and a resistive impedance network A, which is connected to the AC test port and the electric drive system under test through the resistive impedance network B, and connected to the DC power supply through the resistive impedance network C.

[0058] Specifically, the power electronic converter adopts any DC / AC topology, including but not limited to: single-phase two-level half-bridge, single-phase three-level half-bridge, three-phase two-level half-bridge, three-phase three-level half-bridge, and cascaded multi-level topology. Preferably, in this embodiment of the invention, the power electronic converter in the motor simulation device adopts a three-phase two-level half-bridge topology, such as... Figure 2 As shown.

[0059] In a preferred embodiment of the present invention, the impedance network A is used to filter out high-frequency voltage and current ripple. Selectable impedance networks include, but are not limited to: an L-type filter network mainly composed of inductors and resistors, an LCL filter network mainly composed of inductors, capacitors, and resistors, and an LC filter network mainly composed of inductors and capacitors. Preferably, in this embodiment of the present invention, the impedance network A in the motor simulation device adopts an L-type filter network mainly composed of inductors and resistors, such as... Figure 3 As shown.

[0060] In a preferred embodiment of the present invention, the impedance network B is used to suppress common-mode current at the AC terminal. Selectable impedance networks include, but are not limited to, AC common-mode inductors, transformers, etc., wherein the transformer is connected to the AC test port on one side using a delta connection, and the other side using a delta or Y connection. Preferably, in this embodiment of the present invention, the impedance network B is an AC common-mode inductor, such as... Figure 4 As shown.

[0061] In a preferred embodiment of the present invention, the impedance network C is used to suppress common-mode current at the DC end. The selectable impedance network includes, but is not limited to, a DC common-mode inductor. Preferably, in this embodiment of the invention, the impedance network C is a DC common-mode inductor, such as... Figure 5 As shown.

[0062] In a preferred embodiment of the present invention, the functions of each component in the electrical stress control module are as follows:

[0063] The motor simulator controller uses a current closed-loop or voltage open-loop control method based on the reference values ​​generated by the target model group to control and restore the electrical stress of the electric drive system under test.

[0064] A signal generator, connected to the motor simulator controller, generates the control signals required by the electric drive system under test, thus decoupling the controller of the electric drive system under test. Decoupling means that the electric drive system under test and the motor simulator do not require any additional connections not present in the actual electric drive system to function properly. The purpose of decoupling is to enable the motor simulation device to be plug-and-play like a real motor. The signals generated by the signal generator for the electric drive system under test include signals from the resolver and encoder.

[0065] The target model group uses signals readily available from the motor simulator to generate the speed reference, angle reference, voltage reference, and current reference required by the motor simulator controller. The readily available signals from the motor simulator include the motor simulator's modulation signal, the AC test port current signal, and the motor simulator's converter output current signal.

[0066] In a preferred embodiment of the present invention, the motor simulator controller includes a controller and a pulse width modulator; wherein: the controller is used to receive control reference quantities output by the target model group, and generate control signals using current closed-loop / open-loop control, voltage single closed-loop control, voltage double closed-loop control, or voltage open-loop control. The pulse width modulator outputs a switching sequence controlling the simulated converter, so that the AC test port generates the electrical characteristics of the target motor.

[0067] In this embodiment, the current reference value of the motor simulation device is generated by the modulation signal of its own port voltage, the target motor model, and the port filter model. The AC current is reproduced on the AC bus through current closed-loop control, without the need for signal transmission or voltage sampling on the electric drive side.

[0068] Furthermore, the controller is used to control the feedback quantity to track the reference quantity, and the selectable controllers include, but are not limited to, current closed-loop control, voltage dual closed-loop control, etc. The pulse width modulator is used to generate the switching signals for the switching devices, and the selectable pulse width modulation methods include, but are not limited to, SPWM, SVPWM, etc.

[0069] In a preferred embodiment, the controller uses current closed-loop control, and the pulse width modulator is SPWM. The specific process in the motor simulator controller is as follows:

[0070] S11, the current i at the output port of the resistive impedance network A is obtained through the current sampling circuit. s The input is sent to the controller, and after coordinate transformation, the current value under the dq axis is obtained and used as the feedback control signal. The given signal of the controller is the output signal of the target model group.

[0071] S12, the controller's given signal and the current i at the output port of the impedance network A. s After the difference is calculated, it is input to the proportional-integral controller to obtain the output of the proportional-integral controller;

[0072] S13, the controller uses a proportional-integral controller with dq-axis decoupling to achieve zero steady-state error control. The output of the proportional-integral controller is decoupled from the dq-axis to obtain the controller's output e, as shown below. Figure 6 As shown.

[0073] S14, the controller output is the modulation signal e, which is then passed through the pulse width modulator to generate the switching signal of the switching device in the power electronic converter in the motor simulator.

[0074] In a preferred embodiment of the present invention, the signals required by the electric drive system under test generated by the signal generator include signals generated by the rotary transformer and signals generated by the encoder.

[0075] In a preferred embodiment of the present invention, the target model group uses signals readily available from the motor simulator to generate speed reference, angle reference, voltage reference, current reference, etc. required by the motor simulator controller. The signals readily available from the motor simulator include, but are not limited to, the modulation signal of the motor simulator, the current signal of the AC test port, the current signal of the motor simulator converter output, etc., which have low correlation with the electric drive system under test.

[0076] In a preferred embodiment, the signals readily available from the motor simulator include: the modulation signal of the motor simulator and the AC test port current signal; the target model group includes the target motor model G. m (s), resistive network model G f (s); The input to the target motor model is a signal easily obtained by the motor simulator, and the output is the control reference quantity of the motor simulator controller; The impedance network model is the relationship between the current and the two ends of the impedance network.

[0077] Target motor model:

[0078]

[0079] The resistive impedance network model, taking an inductor filter as an example:

[0080]

[0081] Furthermore, the process of generating independently decoupled speed references and angle references is as follows:

[0082] S21, directly obtain the output e of the controller in the motor simulator controller and input it into the target model group;

[0083] S22, by rearranging and combining the electromagnetic equations and resistive network model of the target motor model, we obtain:

[0084]

[0085] In equation (1), ΔR = R s –R f ,ΔL d =L d –L f ,ΔL q =L q –L f Each symbol represents the component u of the controller's output e on the dq axis in the motor simulator controller. ed and u eq The simulated permanent magnet synchronous motor stator current i s Component i on the dq axis d and i q The flux linkage amplitude ψ of the rotor permanent magnet of the simulated permanent magnet synchronous motorf The resistance R in the stator winding of the simulated permanent magnet synchronous motor s The components L of the three-phase inductance in the stator winding of the simulated permanent magnet synchronous motor after dq coordinate transformation d and L q The electric angular frequency ω of the rotor flux linkage rotation of the simulated permanent magnet synchronous motor e The resistor R in the resistive impedance network A f In the resistive impedance network A, the three-phase inductor L f .

[0086] S23, using equation (1), the reference current value i at the AC test port is calculated. d_ref and i q_ref ,like Figure 7 As shown. This current reference value is used to generate the switching signal for the analog-side converter via S11-S14;

[0087] S24, by sampling the current, obtain the AC test port current i s After coordinate transformation, the dq axis components i are obtained. d and i q The torque is calculated using the torque equation to convert the electromagnetic torque T output by the permanent magnet synchronous motor under the same stator current. e .

[0088]

[0089] S25, calculate the mechanical angular frequency ω of the permanent magnet synchronous motor using the equations of motion. m .

[0090]

[0091] S26, Calculate the mechanical angle θ of the permanent magnet synchronous motor using the position equation. m .

[0092]

[0093] In some embodiments, the signal generator is used to provide a speed signal to the electric drive system under test, including but not limited to sine and cosine signals generated by a resolver, and pulse signals generated by an incremental encoder. In this embodiment, the electric drive system under test is completely decoupled from the motor simulation device, and only the necessary signals need to be provided to the electric drive system under test through the signal generator.

[0094] Furthermore, the process of obtaining the current reference is as described in S21-23, which can also be simplified as follows: When the signal easily obtained by the motor simulator is the modulation signal e of the analog converter, the target model group includes: the target motor model G. m (s), resistive network model G f(s), the output of the target model group is the AC test port current reference quantity i ref And satisfy:

[0095]

[0096] Furthermore, the process of obtaining the voltage reference is as follows: After obtaining the AC test port current value through the motor mathematical model, the AC test port voltage reference u can be obtained by calculation according to the formula. ref :

[0097]

[0098] In a preferred embodiment, when the signal readily available from the motor simulator is the AC test port current signal i s At that time, the target model group includes: target motor model G m (s), resistive network model G f (s), the output of the target model group is the analog converter modulation signal e, and satisfies:

[0099]

[0100] The independently decoupled motor simulation device provided in the above embodiments can achieve decoupling from the electric drive converter under test, without relying on the port voltage sampling accuracy of the electric drive converter under test and the signal transmission of the electric drive system, thus realizing plug-and-play functionality of the motor simulation device.

[0101] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various modifications or variations within the scope of the claims, which do not affect the essence of the present invention. The above preferred features can be used in any combination without conflict.

Claims

1. A motor simulation device with independent decoupling, characterized in that: include: A power hardware module used to generate the electrical characteristics of the electric drive system under test; The power hardware module includes a motor simulator, an impedance network B, and an impedance network C. The AC terminal of the motor simulator is connected to the AC test port through the impedance network B and then connected to the electric drive system under test. The DC terminal of the motor simulator is connected to the DC power supply port through the impedance network C. An electrical stress control module, connected to the power hardware module, is used to control the motor simulator and provide mechanical characteristic signals to the electric drive system under test. The electrical stress control module includes a motor simulator controller, a target model group, and a signal generator; Based on the signals readily available from the motor simulator, the control reference quantity of the motor simulator is generated through the target model group, and the motor simulator controller controls the motor simulator to reproduce the electrical characteristics of the target motor in the electric drive system under test at the AC test port, and the mechanical characteristics of the target motor are reproduced at the signal port through the signal generator; The motor simulator includes a power electronic converter and a resistor network A. The external terminal of the power electronic converter is a DC terminal, and the external terminal of the resistor network A is an AC terminal; wherein: The power electronic converter adopts any DC / AC topology or power semiconductor device to reproduce the port voltage and current characteristics of the converter under test in the electric drive system under test. The resistive impedance network A is used for filtering, and it can be a current-mode filter or a voltage-mode filter of any structure. The impedance network B is located at the connection between the AC test port and the power electronic converter to block the common-mode current in the AC bus. The impedance network C is disposed between the power electronic converter and the DC power supply port to block the common-mode current ripple of the DC bus.

2. The independently decoupled motor simulation device according to claim 1, characterized in that: The target model group uses readily available signals from the motor simulator to generate controller reference quantities for the motor simulator. These readily available signals include the motor simulator's modulation signal, AC test port current signal, and motor simulator converter output current signal. The control reference quantities include AC test port voltage reference quantities, AC test port current reference quantities, signal generator speed reference quantities, and signal generator angle reference quantities. The motor simulator controller, based on the control reference quantities generated by the target model group, employs a current closed-loop / open-loop or voltage closed-loop / open-loop control method to control and restore the electrical characteristics of the electric drive system under test. The signal generator is connected to the motor simulator controller and is used to generate the mechanical characteristics required for the control of the electric drive system under test, so as to achieve decoupling between the motor simulator controller and the electric drive system under test.

3. The independently decoupled motor simulation device according to claim 2, characterized in that: When the signal readily available to the motor simulator is the modulation signal e of the analog converter, the target model group includes: target motor model G. m (s), resistive network model G f (s), the output of the target model group is the AC test port current reference quantity i ref And satisfy: 。 4. The independently decoupled motor simulation device according to claim 2, characterized in that: When the readily available signal from the motor simulator is the AC test port current signal is, the target model group includes: a target motor model Gm(s) and a resistive impedance network model Gf(s). The output of the target model group is the analog converter modulation signal e, and satisfies: 。 5. The independently decoupled motor simulation device according to claim 2, characterized in that: When the readily available signal from the motor simulator is the AC test port current signal is, the target model group includes: a target motor model Gm(s), and the output of the target model group is the AC test port voltage reference uref. 。 6. The independently decoupled motor simulation device according to claim 2, characterized in that: The reference value for the speed of the signal generator is obtained by calculating or sampling the current value using mathematical formulas. ； ； Where Te is the electromagnetic torque of the target motor, pn is the number of pairs of magnetic poles per phase of the motor, ψf is the flux linkage amplitude of the permanent magnet of the motor, Ld and Lq are the equivalent inductance values ​​of the d and q axes of the motor stator, Tload is the load torque, J is the equivalent moment of inertia of the motor, ωm is the mechanical angular frequency of the motor, and F is the viscous friction coefficient of the motor. The angle reference value of the signal generator is obtained by integrating the rotational speed reference value of the signal generator.

7. The independently decoupled motor simulation device according to claim 2, characterized in that: The motor simulator controller includes a controller and a pulse width modulator; wherein: The controller is used to receive the control reference quantity output by the target model group, and generate the modulation signal of the motor simulator converter by means of current closed-loop / open-loop control, voltage single closed-loop control, voltage double closed-loop control or voltage open-loop control. The pulse width modulator output controls the switching sequence of the motor simulator, causing the AC test port to generate the electrical characteristics of the target motor.

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