Brushless direct current motor simulator system and method

Abstract

The invention relates to a brushless direct current motor simulator system and method. The brushless direct current motor simulator system comprises a motor simulator unit and an energy feedback unit. In the motor simulator unit, a motor resolving model calculates and outputs three-phase current as instruction current based on an input line voltage and a load torque instruction; the motor simulator unit controller takes an interface input side phase current as a tracking current and adopts a current tracking control strategy based on dynamic current deviation compensation to obtain an instruction voltage so as to drive and control a motor simulation power converter; in the energy feedback unit, a phase-locked loop obtains a power grid phase angle based on alternating current side voltage and current; and the energy feedback unit controller generates instruction voltage by adopting a fixed direct current side voltage control strategy based on power grid voltage orientation so as to drive and control the energy feedback power converter. Compared with the prior art, the square wave current and the trapezoidal wave back electromotive force of the brushless direct current motor and the external port characteristics of the brushless direct current motor under normal operation and fault working conditions can be accurately simulated.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of aerospace technology, in particular to a CMG high-speed rotor brushless DC motor simulator system and a control method thereof. BACKGROUND

[0002] At present, the actuator commonly used in the spacecraft attitude control system mainly includes a jet propeller, a reaction flywheel and a control moment gyroscope (CMG). Among them, the driving motor of the high-speed rotor of the CMG usually selects a brushless DC motor. The high-speed rotor electric drive system of the CMG is the core of the high-speed rotor power system of the CMG, and its performance has an important influence on the reliability and safety of the whole CMG system. Therefore, before the CMG system is put into application, testing and evaluation of the high-speed rotor electric drive system of the CMG is a necessary stage to ensure the performance. The motor simulator can flexibly change the motor parameters, simulate different types of motors according to the needs, and also can modify the motor parameters and load in real time according to the test to simulate the port electrical characteristics of the real motor in different working states such as steady state operation, start-up and overload. It is not limited by the problems of long test period, large occupied space and difficult to realize motor fault test of the traditional test and control platform. At the same time, the energy feedback unit can feedback the power output by the driver to the power grid, saving electricity. Therefore, the research of the motor simulator has great significance for practical application.

[0003] At present, the existing research mainly focuses on the permanent magnet synchronous motor simulator. Since the current waveform of the permanent magnet synchronous motor is a sine wave, the current tracking of the motor simulator is relatively easy. Compared with the permanent magnet synchronous motor, the brushless DC motor adopts square wave driving, has trapezoidal back electromotive force characteristics, and the driving current is usually square wave current, which contains multiple sawtooth-shaped current peaks, greatly increasing the difficulty of current tracking. Therefore, in the research of the brushless DC motor simulator, the simulation of the trapezoidal back electromotive force of the brushless DC motor and the high-precision tracking control of the square wave current face great challenges.

[0004] In the prior art, such as Chinese patent application CN 201810267675.0, a brushless DC motor simulation device with adjustable operating parameters and compatible sensor and sensorless driving methods and a control method are disclosed. In addition, the voltage control adopted in the present application depends on digital analog converter (DAC) and operational amplifier, which is limited by the bandwidth, linearity and response time of the device, which may cause output voltage waveform distortion or dynamic response lag.

[0005] A modified brushless direct current motor simulation system and control method are disclosed in Chinese patent application CN202311186038.8, which switches the phase voltage reconstruction and reference voltage calculation mode through a non-conducting phase judgment module to reduce the interference of high-frequency components on the non-conducting phase of the simulator. However, the non-conducting phase judgment module of the invention relies on specific working conditions and parameter settings, and has poor adaptability to atypical loads or fault conditions, which may lead to misjudgment.

[0006] A linear current source is used as the power amplification unit of the BLDCME to complete the tracking of the command current in the document with DOI number 10.1109 / IECON.2017.8216356, but this scheme cannot simulate the trapezoidal back EMF of the target motor.

[0007] In the document with DOI number 10.1007 / 978-981-96-1387-8_13, a two-level VSC is used as the power amplification unit of the BLDCME, and a deadbeat predictive current control is used as the control strategy of the BLDCME to realize the simulation of the square wave current and trapezoidal back EMF of the target motor, but the control effect of this control strategy is limited by the interface filter parameters, resulting in a decrease in current tracking accuracy. SUMMARY

[0008] The purpose of the present application is to solve the problems existing in the prior art and provide a CMG high-speed rotor brushless direct current motor simulator system and its control method.

[0009] The purpose of the present application can be achieved by the following technical solutions: As a first aspect of the present application, a brushless direct current motor simulator system is provided, which comprises a motor simulator unit and an energy feedback unit; The main circuit of the motor simulator unit comprises a fault switching circuit, an interface filter circuit and a motor simulation power converter connected in sequence, and the input side of the fault switching circuit is connected with the output side of the motor driver; the control circuit of the motor simulator unit comprises a motor solving model, a motor simulator unit controller and a motor simulator unit PWM drive circuit connected in sequence; The input side of the motor solving model is connected with the line voltage sampling circuit of the AC output side of the motor driver to obtain the line voltage output by the motor driving unit, and the motor solving model calculates the output three-phase current based on the line voltage and the load torque command as the command current of the motor simulator unit controller, while outputting physical quantities including the Hall signal for the closed-loop control of the motor driver and the monitoring of the motor operating state; The motor simulator unit controller input side is connected with a motor solution model to obtain an instruction current, and the motor simulator unit controller input side is connected with an interface filter circuit input side phase current sampling circuit to obtain a tracking current, the motor simulator unit controller adopts a current tracking control strategy based on dynamic current deviation compensation to obtain an instruction voltage, and the motor simulator unit controller drives the motor simulator unit PWM drive circuit to drive and control the motor simulator power converter; The main loop of the energy feedback unit includes an energy feedback power converter and a grid-connected filter circuit, the energy feedback power converter input side is connected with the motor simulator power converter output side, the energy feedback power converter output side is connected with the grid-connected filter circuit, and the grid-connected filter circuit feeds back the motor simulator unit energy to a three-phase power grid; the control loop of the energy feedback unit includes a phase-locked loop, an energy feedback unit controller and an energy feedback unit PWM drive circuit connected in sequence; The phase-locked loop input side is connected with an energy feedback unit alternating current side voltage and current sampling circuit to obtain an energy feedback unit alternating current side voltage and current, and extract a power grid phase angle; the energy feedback unit controller adopts a direct current side voltage control strategy based on power grid voltage orientation to generate an instruction voltage, converts the instruction voltage through the power grid phase angle to obtain an instruction voltage in a synchronous stationary coordinate system, and drives and controls the energy feedback power converter through the energy feedback unit PWM drive circuit.

[0010] As a preferred technical solution, the motor simulator power converter includes a T-type three-level PWM rectifier, and the T-type three-level PWM rectifier is composed of three-phase bridge arms and a direct current side capacitor; The direct current side is composed of two symmetrically distributed capacitors to form a voltage division capacitor group for providing a stable midpoint potential; Each phase bridge arm includes two main power switching tubes and two intermediate auxiliary power switching tubes, and each power switching tube is connected with a reverse freewheeling diode in parallel, wherein the main power switching tubes of the upper and lower bridge arms are connected with a direct current bus, and the intermediate auxiliary power switching tubes are connected in back-to-back to the midpoint of the voltage division capacitor group to realize switching between the output voltage level and the direct current midpoint, so that three levels of each phase output are realized.

[0011] As a preferred technical solution, the fault switching circuit is composed of contactors and fault resistors; A first fault simulation resistor is connected in series on each fault phase, and each first fault simulation resistor is connected in parallel with a first contactor, which is used to simulate a stator resistance imbalance fault of the motor; A second fault simulation resistor is connected between two fault phases, and each second fault simulation resistor is connected in series with a second contactor, which is used to simulate a phase-to-phase short circuit fault of the motor; A third contactor is arranged on each fault phase to control the fault phase circuit breaking, which is used to simulate an open circuit fault of the motor.

[0012] As a preferred technical scheme, the energy feedback power converter is composed of a two-level PWM inverter, the two-level PWM inverter adopts a three-phase half-bridge structure, each group of bridge arms is composed of an upper bridge arm switch tube and a lower bridge arm switch tube, and each power tube is connected in parallel with a reverse current diode; the direct current side is connected to the positive and negative bus through an energy storage capacitor; and the three-phase alternating current side output end is connected to a three-phase power grid through a filtering circuit.

[0013] As a second aspect of the present application, a brushless direct current motor simulation method is provided, the method is based on the brushless direct current motor simulator system as described above, and the specific steps are as follows: The motor simulator unit adopts a current tracking control strategy based on dynamic current deviation compensation, the motor simulator command voltage is obtained by solving a discrete current prediction equation of the target motor and the motor simulator; the command voltage is compensated according to the deviation between the tracking current effective value and the command current effective value; and the switching signal of the motor simulation power converter is generated through a modulation algorithm; The energy feedback unit adopts a direct current side voltage control strategy based on grid voltage orientation, the voltage outer ring takes the direct current side bus voltage as the control object, compares the reference voltage and the actual voltage, and outputs the direct axis reference current; the quadrature axis reference current is set to zero, the current inner ring takes the current tracking as the target, compares the reference current with the actual current to generate the command voltage, and the command voltage is transformed to the synchronous stationary coordinate system through the grid phase angle obtained by the phase-locked loop; and the switching signal of the energy feedback power converter is generated through a modulation algorithm.

[0014] As a preferred technical scheme, the current tracking control strategy based on dynamic current deviation compensation is specifically as follows: The motor drive output side line voltage is sampled and taken as the input of the motor calculation model together with the load torque command, the three-phase current is calculated as the command current, and the motor Hall signal and back electromotive force are outputted; According to the discrete current prediction equation of the target motor and the motor simulator, the back electromotive force is taken as the calculation variable, the tracking current at the next moment is equal to the command current, and the preliminary command voltage is obtained by solving; The interface filtering circuit input side phase current is sampled as the tracking current; According to the running state of the motor, the compensation voltage is obtained according to the deviation between the tracking current effective value and the command current effective value; Combined with the Hall signal, the compensation voltage is used to correct the preliminary command voltage to obtain the final command voltage, and the switching signal of the motor simulation power converter is generated through a modulation algorithm.

[0015] As a preferred technical scheme, for different motor running states, the compensation voltage is specifically obtained as follows: When the simulation motor is in normal state, the direct current equivalent currents of the command current and the tracking current are constructed in combination with the Hall signals, the effective values of the direct current equivalent currents of the command current and the tracking current are calculated respectively using a sliding window, and the compensation voltage is obtained based on the difference between the effective values of the two currents through a control algorithm; When the simulation motor is in a fault state, the effective values of the three-phase command current and the tracking current are calculated respectively, and the compensation voltage is obtained based on the difference between the effective values of the two currents through a control algorithm.

[0016] As a preferred technical solution, the direct current side voltage control strategy based on grid voltage orientation is specifically as follows: The AC side voltage and current of the energy feedback unit are obtained, the grid phase angle is obtained through a phase-locked loop, and a rotating coordinate system synchronized with the grid voltage is established, the grid voltage is decomposed into a direct-axis component and an alternating-axis component in the rotating coordinate system to obtain a feedforward compensation amount, and the filter inductance current is decomposed into a direct-axis component and an alternating-axis component to obtain an actual current; The voltage outer loop takes the DC side bus voltage as a control object, samples the DC side voltage of the energy feedback unit as an actual voltage, compares the reference voltage with the sampled DC bus actual voltage, and outputs a direct-axis reference current through a control algorithm; The current inner loop takes current tracking as a target, sets the alternating-axis reference current to zero, compares the reference current with the alternating and direct-axis components of the filter inductance actual current, and generates alternating and direct-axis command voltages through a control algorithm; For the generated alternating and direct-axis command voltages, cross-coupling compensation and grid voltage feedforward are introduced to realize decoupling control; The compensated command voltage is subjected to coordinate inverse transformation based on the grid phase angle obtained through the phase-locked loop to obtain a command voltage in the synchronous stationary coordinate system, and a switching signal of the energy feedback power converter is generated through a modulation algorithm.

[0017] As a preferred technical solution, the cross-coupling compensation and grid voltage feedforward are specifically as follows: The product of the electrical angular frequency of the grid side AC voltage, the inductance value of the grid-connected filter circuit and the alternating-axis component of the filter inductance current is added to the direct-axis voltage command, and the product of the electrical angular frequency of the grid side AC voltage, the inductance value of the grid-connected filter circuit and the direct-axis component of the filter inductance current is subtracted from the alternating-axis voltage command, and the direct-axis and alternating-axis components of the grid voltage are introduced as feedforward signals to perform feedforward compensation on the direct-axis and alternating-axis command voltages.

[0018] As a preferred technical solution, the method simulates the external port characteristics of the brushless direct current motor under three fault conditions of stator resistance imbalance, open circuit fault and phase-to-phase short circuit fault through a fault switching circuit, and is specifically as follows: When the simulation motor is in a stator resistance imbalance fault, the first contactor is controlled to disconnect the corresponding fault phase and connect the corresponding first fault simulation resistance; When the simulation motor is in an open circuit fault, the third contactor is controlled to disconnect the corresponding fault phase. When the simulation motor is in an open circuit fault, the third contactor is controlled to disconnect the corresponding fault phase.

[0019] Compared with the prior art, the present application has the following beneficial effects: 1) The brushless direct current motor simulator power stage conversion device adopted by the present application can flexibly modify the motor type and motor parameters compared with the signal level hardware-in-the-loop system test technology and the traditional electric drive system test bench, can provide different load working conditions for different test requirements, can simulate the electrical external port characteristics of the motor under different working conditions such as steady-state operation, starting, overload, normal operation and fault, thereby reducing the development cost, accelerating the research and development progress, and providing a complete electric drive system test and verification environment for component suppliers; the power electronic components (such as inverters) that bear high voltage and large current during actual system operation can be tested.

[0020] 2) The current tracking control strategy based on dynamic current deviation compensation adopted by the present application has the ability to simulate the square wave current and trapezoidal back electromotive force of the target brushless direct current motor, and solves the problems of insufficient square wave current tracking accuracy and difficulty in simulating trapezoidal wave back electromotive force existing in the prior art.

[0021] 3) The present application adopts a topology structure of three-level PWM rectifier + two-level PWM inverter, which can simulate the trapezoidal back electromotive force of the brushless direct current motor without the need for an external linear voltage source, and can control the bidirectional flow of energy, feed the energy of the motor simulator system back to the power grid, and realize green energy saving of the test.

[0022] 4) The present application can simulate the external port characteristics under three fault working conditions of brushless direct current motor stator resistance imbalance, open circuit fault and interphase short circuit fault, and solves the problem that the traditional electric drive test platform is difficult to realize motor fault test.

[0023] 5) The motor solution model in the present application is based on the FPGA real-time operation unit, which meets the requirements of high precision and high real-time of the motor solution model, the motor simulator unit controller and the energy feedback unit controller are based on the DSP embedded digital control chip, which meets the requirements of microsecond-level response of the control link of the motor simulator, and can realize real-time monitoring of motor parameter setting, working condition setting and key state quantity of the motor. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 is a schematic diagram of the overall structure of the brushless direct current motor simulator system of the present application; Figure 2Fig. 1 is a schematic diagram of a motor simulator unit in the embodiment of the present application; Figure 3 Fig. 2 is a control block diagram of a control strategy of the motor simulator unit in the embodiment of the present application under normal state of the motor; Figure 4 Fig. 3 is a control block diagram of a control strategy of the motor simulator unit in the embodiment of the present application under fault state of the motor; Figure 5 Fig. 4 is a schematic diagram of an energy feedback power converter in the embodiment of the present application; Figure 6 Fig. 5 is a control block diagram of a control strategy of an energy feedback unit in the embodiment of the present application; Figure 7 Fig. 6 is a schematic diagram of a phase-locked loop used in the control system of the energy feedback unit in the embodiment of the present application; Figure 8 Fig. 7 is a schematic diagram of a fault switching circuit of the motor simulator unit in the embodiment of the present application; Figure 9 、 Figure 10 Fig. 8 is a test result of port characteristics of the motor simulator under steady state working condition 1 in the embodiment of the present application; Figure 11 、 Figure 12 Fig. 9 is a test result of port characteristics of the motor simulator under steady state working condition 2 in the embodiment of the present application; Figure 13 Fig. 10 is a test result of port characteristics of the motor simulator under dynamic working condition in the embodiment of the present application.

[0025] In the figures, 1 is a motor simulation power converter, 2 is a fault switching circuit, 3 is an interface filter circuit, 4 is a driver output side line voltage sampling circuit, 5 is a motor solution model, 6 is a motor simulator unit controller, 7 is an interface filter circuit input side phase current sampling circuit, 8 is a motor simulator unit PWM drive circuit, 9 is an energy feedback power converter, 10 is a grid-connected filter circuit, 11 is an energy feedback unit DC side voltage sampling circuit, 12 is an energy feedback unit controller, 13 is a phase-locked loop, 14 is an energy feedback unit AC side voltage and current sampling circuit, 15 is an energy feedback unit PWM drive circuit, and 16 is a motor parameter setting, working condition setting and running state monitoring module. DETAILED DESCRIPTION

[0026] The present application will be described in detail below in conjunction with the accompanying drawings and specific embodiments. The present embodiment is implemented on the premise of the technical solution of the present application, and detailed implementation manners and specific operation processes are given, but the protection scope of the present application is not limited to the following embodiments.

[0027] The present application relates to a CMG high-speed rotor brushless DC motor simulator system, as shown in the figure, which comprises a motor simulator unit and an energy feedback unit. Figure 1 The present application relates to a CMG high-speed rotor brushless DC motor simulator system, as shown in the figure, which comprises a motor simulator unit and an energy feedback unit.

[0028] The main circuit of the motor simulator unit comprises a motor simulation power converter 1, a fault switching circuit 2 and an interface filter circuit 3. The control circuit of the motor simulator unit comprises a driver output side line voltage sampling circuit 4, an interface filter circuit input side phase current sampling circuit 7, a motor calculation model 5, a motor simulator unit controller 6 and a motor simulator unit PWM drive circuit 8.

[0029] The main circuit of the energy feedback unit comprises an energy feedback power converter 9 and a grid-connected filter circuit 10. The control circuit of the energy feedback unit comprises an energy feedback unit DC side voltage sampling circuit 11, an energy feedback unit AC side voltage and current sampling circuit 14, a phase-locked loop 13, an energy feedback unit controller 12 and an energy feedback unit PWM drive circuit 15. The motor parameter setting, working condition setting and operating state monitoring module 16 is connected to the motor simulator unit and the energy feedback unit respectively.

[0030] The input side of the fault switching circuit 2 is connected to the output side of the motor driver. The output side of the fault switching circuit 2 is connected to the input side of the interface filter circuit 3. The output side of the interface filter circuit 3 is connected to the input side of the motor simulation power converter 1. The motor calculation model 5, the motor simulator unit controller 6 and the motor simulator unit PWM drive circuit 8 are connected in sequence. The energy feedback power converter 9 is connected to the grid-connected filter circuit 10. The phase-locked loop 13, the energy feedback unit controller 12 and the energy feedback unit PWM drive circuit 15 are connected in sequence.

[0031] Further, the topology of the motor simulation power converter 1 is as shown in Figure 2 It is a T-type three-level PWM rectifier topology, which is composed of three-phase bridge arm structure and DC side capacitor. The three-phase bridge arms are A phase, B phase and C phase. Each phase bridge arm is composed of two main power switch tubes and two intermediate auxiliary switch tubes, which are , , , , , , , , , , , , of which the upper and lower bridge arm main power switch tubes are used to connect the DC bus. The intermediate auxiliary switch tubes are connected back to back, which is used to realize the switching between the output voltage level and the DC midpoint, so as to make each phase output three levels. The DC side is composed of two symmetrically distributed capacitors and to form a voltage dividing capacitor group, which provides a stable midpoint potential.

[0032] Further, the motor simulator unit controller 6 is based on a DSP embedded digital control chip, and adopts a current tracking control strategy based on dynamic current deviation compensation, and its control block diagram is shown in Figure 3 、 Figure 4 . First, the discrete current prediction equation is obtained according to the circuit model of the target motor and the motor simulator, and the tracking current at k+1 time is equal to the command current, and the preliminary command voltage is obtained by solving 、 、 , wherein the command current 、 、 and the tracking current 、 、 are subjected to low-pass filtering processing. On this basis, dynamic current deviation compensation is further introduced, and is processed according to the running state of the motor. When the simulated motor is in a normal state, the direct current equivalent current of the command current and the direct current equivalent current of the tracking current are constructed in combination with the Hall signal, and the effective values thereof are calculated using a sliding window effective value calculation module, and the difference between the effective values is sent to a PI regulator to obtain the compensation voltage ; when the simulated motor is in a fault state, the effective values of the three-phase command current and the tracking current are calculated, and the difference between the effective values is sent to a PI regulator to obtain three-phase compensation voltage . Finally, the compensation voltage is used to correct the preliminary command voltage in combination with the Hall signal to obtain the final command voltage 、 、 , and the switching signal of the motor simulation power converter 1 is generated through the SVPWM modulation algorithm.

[0033] Further, the energy feedback power converter 9 has a topology as shown in Figure 5 , which is a two-level PWM inverter topology structure, including three groups of bridge arms, each group of bridge arms being composed of an upper bridge arm switch tube and a lower bridge arm switch tube, respectively and for phase A, and for phase B, and and for phase C, and each power tube is connected in parallel with a reverse current diode. The DC side is connected to the positive and negative bus through an energy storage capacitor , providing a stable DC voltage for the converter. The three-phase AC side output of the converter is connected to the power grid after filtering circuit.

[0034] Furthermore, both the energy feedback unit controller 12 and the phase-locked loop 13 operate based on a DSP embedded digital control chip, employing a constant DC-side voltage control strategy based on grid voltage orientation. Their control block diagram is shown below. Figure 6 As shown. First, the grid-connected voltage is sampled, and the grid phase angle is extracted through phase-locked loop 13. This establishes a rotating coordinate system synchronized with the grid voltage, as shown in the schematic diagram of phase-locked loop 13. Figure 7 As shown. In this coordinate system, the grid voltage is decomposed into direct-axis components. and cross-axis components The filter inductor current is decomposed into direct-axis components. and cross-axis components The outer voltage loop uses the DC-side bus voltage as the control object, and sets the reference voltage... and actual voltage Comparison: The direct-axis reference current output by the PI regulator This is to stabilize the DC-side voltage of the energy feedback unit. The quadrature-axis reference current is set to zero, i.e., let... This is to achieve unity power factor grid connection for the energy feedback unit. The inner current loop aims at current tracking, using the reference current... , With actual current , The command voltage is generated by the PI regulator. , To overcome cross-coupling caused by inductance parameters, compensation is performed in the direct-axis voltage command. The term is compensated in the quadrature axis voltage command. The item also introduces the grid voltage component. and As a feedforward signal, it enables decoupling control of the current loop. Among other things, The electrical angular frequency of the grid-side AC voltage. L This represents the inductance value of the grid-connected filter circuit. Finally, the command voltage is obtained in the synchronous stationary coordinate system after inverse coordinate transformation. , The switching signal for the energy feedback power converter 9 is generated using the SVPWM modulation algorithm.

[0035] Furthermore, the topology of fault switching circuit 2 is as follows: Figure 8 As shown, this circuit consists of nine contactors and six fault resistors, and can be used to simulate stator resistance imbalance faults, phase-to-phase short circuit faults, and open circuit faults in a brushless DC motor. Contactors ~ Control the introduction of a fault resistor in the faulty phase , , Simulate stator resistance unbalance fault of motor, contactor Control fault resistance connected between fault two phases Simulate inter-phase short circuit fault of motor, contactor Control fault phase open circuit fault of motor, contactor Normally closed, contactor Normally open, contactor Normally closed.

[0036] Further, the driver output side line voltage sampling circuit 4 selects LEM CV 3-100 / SP3 voltage sensor, and the sampled line voltage will be used as the voltage input of the motor calculation model 5 for solving the command current. The interface filter circuit input side phase current sampling circuit 7 selects Hall current sensor LAH 50, and the sampled phase current is the tracking current of the motor simulator, and the tracking current and the command current are input to the motor simulator unit controller 6 to dynamically adjust the voltage, so as to realize the closed-loop control of the motor simulator unit.

[0037] Further, the motor simulator unit controller 6 and the energy feedback unit controller 12 both select TMS320F28335 type DSP embedded digital control chip of Texas Instruments Company as the main control calculation core, the chip has ePWM, QEP, SCI and many other peripheral modules, and can meet the design needs of different control algorithms of the system. The control logic of the motor simulator unit controller 6 and the energy feedback unit controller 12 adopts the design idea based on model (Mode Based Design, MBD), and the embedded C code is generated by using the Matlab / Simulink automatic code generation technology.

[0038] ​​​​​​​Further, the motor solution model 5 is based on FPGA real-time operation unit, which can realize microsecond time step simulation, and meet the requirements of high precision and high real-time of the motor solution model. The motor solution model includes voltage equation, torque equation and motion equation of the motor, and involves motor parameters such as stator winding resistance, phase inductance, moment of inertia, torque coefficient, etc. The motor solution model 5 can also use a finite element motor model based on a finite element lookup table, which is used to consider the nonlinear problems caused by the saturation of the motor magnetic core, high-order harmonics, slotting effect, etc. The model takes the port voltage and load torque as input, calculates the motor current in real time as the command current of the motor simulator unit, and calculates the back electromotive force as a calculation variable in the motor simulator control strategy to provide reference information for back electromotive force simulation. In addition, the motor solution model 5 can also calculate the virtual speed, virtual electromagnetic torque, Hall signal, virtual angular position, etc., to realize the closed-loop control of the motor driver and the monitoring of the motor operating state.

[0039] The brushless DC motor simulator system of the present application works in the following way: The motor simulator unit control system first samples the output side line voltage of the motor driver output side voltage sampling circuit 4 to obtain , 、 , and sends it to the FPGA real-time operation unit of the motor solution model 5, together with the load torque command T L , as the input of the motor solution model 5. The motor solution model 5 calculates the three-phase current , , as the command current of the motor simulator unit. At the same time, the motor solution model 5 outputs the back electromotive force as a calculation variable in the motor simulator control strategy, providing reference information for the simulation of the motor simulator back electromotive force. In addition, the motor solution model 5 outputs the virtual speed, virtual torque, rotor angular position, Hall signal and other physical quantities of the motor, which are used for closed-loop control of the motor driver and monitoring of the motor operating state. Then the interface filter circuit input side phase current is sampled to obtain the tracking current , , . The discrete current prediction equation is obtained by combining the mathematical model of the target motor and the motor simulator, and the command voltage is solved. The command voltage is compensated according to the deviation between the tracking current effective value and the command current effective value. Finally, the switching signal of the motor simulation power converter 1 is generated through the SVPWM modulation algorithm, so as to realize the tracking of the command current output by the motor solution model 5 of the motor simulator unit, and thus complete the simulation of the port electrical characteristics of the target motor. On the other hand, the energy feedback unit control system first samples the grid-connected voltage, and then extracts the phase angle , thereby establishing a rotating coordinate system synchronized with the power grid. The voltage outer loop takes the DC side bus voltage as the control object, outputs the direct axis reference current, and sets the cross axis reference current to zero to achieve unity power factor grid connection. The current inner loop compares the reference current with the actual current, and the deviation is adjusted by the PI regulator to obtain the command voltage 、 At the same time, the grid voltage feedforward and cross coupling compensation are introduced to realize the decoupling control of the direct axis and cross axis currents, thereby obtaining the direct axis and cross axis voltage commands, and generating the switching signal of the energy feedback power converter 9 through the SVPWM modulation algorithm to realize the energy feedback unit to feedback energy to the grid under the conditions of high power factor and low harmonic content, while maintaining the stability of the DC side voltage of the energy feedback unit.

[0040] Further, in the present embodiment, when the simulated motor is in a stator resistance imbalance fault, the contactors ~ corresponding to the fault phase are controlled to be disconnected, and the fault resistance is connected 、 、 When the simulated motor is in an inter-phase short circuit fault, the contactors ~ corresponding to the fault phase are controlled to be closed, and the fault resistance is connected 、 、 When the simulated motor is in an open circuit fault, the contactors ~ corresponding to the fault phase are controlled to be disconnected.

[0041] The specific working process of the motor simulator unit of the brushless direct current motor simulator system is as follows: 1.1) Obtain the motor drive output side line voltage as the input quantity of the motor solving model, solve the motor current, Hall signal, etc., and obtain the motor simulator unit command current; 1.2) Sample the interface filter circuit input side phase current and compare it with the command current, and obtain the control signal of each switch tube of the motor simulator unit through the motor simulator unit controller; 1.3) Convert the PWM control signal through the motor simulator unit PWM drive circuit into the PWM drive signal of the switch tube of the motor simulator power converter, and then realize the turn-on and turn-off of the switch tube, so that the motor simulator unit and the target motor have the same external port characteristics.

[0042] The specific working process of the energy feedback unit is as follows: 2.1) Obtain the DC side voltage of the energy feedback unit as the input of the voltage outer loop of the energy feedback unit controller, and obtain the AC side voltage and current of the energy feedback unit and the phase-locked loop to obtain the electrical angle of the energy feedback unit controller; 2.2) The voltage outer loop compares the sampled DC bus voltage with the reference voltage, and generates a reference current through a PI regulator; the current inner loop takes unit power factor as the control target, and outputs the control signals of the switches of the energy feedback power converter in combination with the electrical angle obtained by the phase-locked loop; 2.3) The PWM control signal is converted into the PWM drive signal of the switch of the energy feedback power converter through the PWM drive circuit of the energy feedback unit, and then the switch is turned on and off, so that the energy feedback unit can feedback energy to the power grid under the condition of high power factor and low harmonic content, while maintaining the stability of the DC side voltage of the energy feedback unit.

[0043] Embodiment 2 As one of the specific embodiments of the present application, this embodiment is verified by a simulation method. The verification environment is that under the same test conditions, the motor driver adopts a closed-loop operation mode to provide driving input for the motor simulator, tests and verifies under different working conditions, and compares with the target motor operating state quantity.

[0044] The target motor simulated in this embodiment is a brushless direct current motor with 8 pole pairs, the motor phase inductance is 15 , the motor phase resistance is 0.3 , the torque constant is 0.025 , and the moment of inertia is 0.126 . The resistance of the interface filter circuit 3 is 0.3 , the inductance of the interface filter circuit 3 is 15 , the switching frequency of the motor driver is 20 kHz, the switching frequency of the motor simulator is 100 kHz, the DC bus voltage of the motor driver is 30 V, and the DC bus voltage of the motor simulation power converter 1 is 30 V. In this embodiment, the same motor driver is connected to the target motor and the motor simulator respectively, and the performance of the motor simulator is tested by comparing the port electrical characteristics and mechanical characteristics of the target motor and the brushless direct current motor simulator.

[0045] Verification condition one: speed 5000r / min, load 0.05 . The test results are shown in Figure 9 , Figure 10 , Figure 9 In window one is the motor simulator A phase tracking current, is the motor simulator A phase command current, in window two is the motor simulator A phase tracking current, Target motor A phase current, in window three Motor emulator virtual speed, Target motor speed, in window four Motor emulator virtual electromagnetic torque, Target motor electromagnetic torque. Figure 10 In window one Target motor A phase terminal voltage, in window two Motor emulator A phase terminal voltage. Test results show that the proposed control strategy has good steady-state performance and can well simulate the external port characteristics of the brushless DC motor under steady-state working conditions.

[0046] Verification condition two: speed 9000r / min, load 0.05 . Test results are shown in Figure 11 , Figure 12 , Figure 11 In window one Motor emulator A phase tracking current, Motor emulator A phase command current, in window two Motor emulator A phase tracking current, Target motor A phase current, in window three Motor emulator virtual speed, Target motor speed, in window four Motor emulator virtual electromagnetic torque, Target motor electromagnetic torque. Figure 12 In window one Target motor A phase terminal voltage, in window two Motor emulator A phase terminal voltage. Test results show that the proposed control strategy has good steady-state performance and can well simulate the external port characteristics of the brushless DC motor under steady-state working conditions.

[0047] Verification condition three: speed 9000r / min, load from 0.02 to 0.05 , test results are shown in Figure 13 , in window one Motor emulator A phase tracking current, Motor emulator A phase command current, in window two Motor emulator A phase tracking current, Target motor A phase current, in window three Motor emulator virtual speed, Target motor speed, in window four Motor emulator virtual electromagnetic torque, The target motor electromagnetic torque is obtained. Test results show that the proposed control strategy has good dynamic performance and can effectively simulate the external port characteristics of the brushless DC motor under dynamic working conditions.

[0048] The preferred embodiments of the present application are described in detail above. It should be understood that those of ordinary skill in the art can make modifications and variations without departing from the concept of the present application. Therefore, any technical solutions obtained by logical analysis, reasoning or limited experiments based on the concept of the present application and the prior art in the technical field should be within the protection scope defined by the claims.

Claims

1. A brushless DC motor simulator system, characterized by, The system comprises a motor simulator unit and an energy feedback unit; The main circuit of the motor simulator unit comprises a fault switching circuit (2), an interface filter circuit (3) and a motor simulation power converter (1) connected in sequence, and the input side of the fault switching circuit (2) is connected with the output side of the motor driver; the control circuit of the motor simulator unit comprises a motor solution model (5) and a motor simulator unit controller (6) connected in sequence; The input side of the motor solution model (5) is connected with a line voltage sampling circuit (4) of the AC output side of the motor driver to obtain the line voltage output by the motor driving unit, and the motor solution model (5) calculates the output three-phase current as the instruction current of the motor simulator unit controller (6) based on the line voltage and the load torque instruction, and simultaneously outputs physical quantities including the Hall signal for the closed-loop control of the motor driver and the monitoring of the motor operating state; The input side of the motor simulator unit controller (6) is connected with the motor solution model (5) to obtain the instruction current, and simultaneously connected with a phase current sampling circuit (7) of the input side of the interface filter circuit to obtain the tracking current, and the motor simulator unit controller (6) adopts a current tracking control strategy based on dynamic current deviation compensation to obtain the first instruction voltage and drive the control of the motor simulation power converter (1); The main circuit of the energy feedback unit comprises an energy feedback power converter (9) and a grid-connected filter circuit (10), the input side of the energy feedback power converter (9) is connected with the output side of the motor simulation power converter (1), the output side of the energy feedback power converter (9) feeds back the energy of the motor simulator unit to the three-phase power grid through the grid-connected filter circuit (10); the control circuit of the energy feedback unit comprises a phase-locked loop (13) and an energy feedback unit controller (12) connected in sequence; The input side of the phase-locked loop (13) is connected with an AC side voltage and current sampling circuit (14) of the energy feedback unit to obtain the AC side voltage and current of the energy feedback unit and extract the grid phase angle; the energy feedback unit controller (12) adopts a direct DC side voltage control strategy based on the grid voltage orientation to generate the second instruction voltage, converts the second instruction voltage in the synchronous stationary coordinate system through the grid phase angle, and drives the control of the energy feedback power converter (9).

2. A brushless DC motor simulator system according to claim 1, wherein, The motor simulation power converter (1) comprises a T-type three-level PWM rectifier composed of three-phase bridge arms and a DC side capacitor; The DC side is composed of two symmetrically distributed capacitor groups for providing a stable midpoint potential; Each phase bridge arm comprises two main power switching tubes and two intermediate auxiliary power switching tubes, and each power switching tube is connected in parallel with a reverse freewheeling diode, wherein the main power switching tubes of the upper and lower bridge arms are connected with the DC bus, and the intermediate auxiliary power switching tubes are connected in back-to-back to the midpoint of the voltage division capacitor group for switching between the output voltage level and the DC midpoint, so as to make each phase output three levels.

3. A brushless DC motor simulator system according to claim 1, wherein, The fault switching circuit (2) is composed of a contactor and a fault resistor. A first fault simulation resistor is connected in series with each fault phase, and each first fault simulation resistor is connected in parallel with a first contactor, for simulating a stator resistance imbalance fault of the motor; A second fault simulation resistor is connected between two fault phases, and each second fault simulation resistor is connected in series with a second contactor, for simulating an inter-phase short circuit fault of the motor; A third contactor is arranged on each fault phase to control the disconnection of the fault phase, for simulating an open circuit fault of the motor.

4. A brushless DC motor simulator system according to claim 1, wherein, The energy feedback power converter (9) is composed of a two-level PWM inverter, the two-level PWM inverter adopts a three-phase half-bridge structure, each bridge arm is composed of an upper bridge arm switch tube and a lower bridge arm switch tube, and each power tube is connected in parallel with a reverse current diode; the direct current side is connected to the positive and negative bus through an energy storage capacitor; and the three-phase alternating current side output end is connected to a three-phase power grid through a filtering circuit.

5. A method of simulating a brushless DC motor, characterized by, The method is based on the brushless direct current motor simulator system of any one of claims 1-4, and the specific steps are as follows: The motor simulator unit adopts a current tracking control strategy based on dynamic current deviation compensation, and the motor simulator command voltage is obtained by solving the discrete current prediction equation of the target motor and the motor simulator; The command voltage is compensated according to the deviation between the tracking current effective value and the command current effective value; and the switching signal of the motor simulation power converter is generated through a modulation algorithm; The energy feedback unit adopts a direct current side voltage control strategy based on grid voltage orientation, the voltage outer ring takes the direct current side bus voltage as the control object, compares the reference voltage and the actual voltage, and outputs the direct axis reference current; The quadrature axis reference current is set to zero, the current inner ring takes current tracking as the target, compares the reference current with the actual current to generate the command voltage, and the grid phase angle obtained through the phase-locked loop (13) is used to transform the command voltage to the synchronous stationary coordinate system; The switching signal of the energy feedback power converter is generated through a modulation algorithm.

6. The method of claim 5, wherein, The current tracking control strategy based on dynamic current deviation compensation is as follows: The motor drive output side line voltage is sampled and used as the input of the motor solving model (5) together with the load torque command, the three-phase current is calculated as the command current, and the motor Hall signal and back electromotive force are output; According to the discrete current prediction equation of the target motor and the motor simulator, the back electromotive force is used as the calculation variable, the next time tracking current is equal to the command current, and the preliminary command voltage is obtained by solving; The interface filtering circuit input side phase current is sampled as the tracking current; According to the running state of the motor, the compensation voltage is obtained according to the deviation between the tracking current effective value and the command current effective value; Combined with the Hall signal, the compensation voltage is used to modify the preliminary command voltage to obtain the final command voltage, and the switching signal of the motor simulation power converter (1) is generated through a modulation algorithm.

7. A method of simulating a brushless DC motor as claimed in claim 6, wherein, For different motor running states, the compensation voltage is obtained as follows: When the simulation motor is in a normal state, the direct current equivalent currents of the command current and the tracking current are constructed combined with the Hall signal, the effective values of the direct current equivalent currents of the command current and the tracking current are calculated using a sliding window, and the compensation voltage is obtained based on the difference between the effective values of the two currents through a control algorithm. When the simulation motor is in a fault state, effective values of three-phase instruction currents and tracking currents are calculated respectively, and a compensation voltage is obtained based on a difference between the effective values of the two through a control algorithm.

8. The method of claim 5, wherein, The direct current side voltage control strategy based on grid voltage orientation is as follows: The AC side voltage and current of the energy feedback unit are obtained, the grid phase angle is obtained through a phase-locked loop (13), and a rotating coordinate system synchronized with the grid voltage is established, the grid voltage is decomposed into a direct-axis component and an alternating-axis component in the rotating coordinate system to obtain a feedforward compensation amount, and the filter inductance current is decomposed into a direct-axis component and an alternating-axis component to obtain an actual current; The outer voltage loop takes the DC side bus voltage as a control object, samples the DC side voltage of the energy feedback unit as an actual voltage, compares the reference voltage with the sampled DC bus actual voltage, and outputs a direct-axis reference current through a control algorithm; The current inner loop takes current tracking as a target, sets the alternating-axis reference current to zero, compares the reference current with the alternating and direct-axis components of the filter inductance actual current, and generates alternating and direct-axis instruction voltages through a control algorithm; For the generated alternating and direct-axis instruction voltages, cross-coupling compensation and grid voltage feedforward are introduced to realize decoupling control; The compensated instruction voltage is subjected to coordinate inverse transformation based on the grid phase angle obtained by the phase-locked loop (13) to obtain an instruction voltage in the synchronous stationary coordinate system, and a switching signal of the energy feedback power converter (9) is generated through a modulation algorithm.

9. The method of claim 8, wherein, The cross-coupling compensation and grid voltage feedforward are as follows: In the direct-axis voltage instruction, the product of the electrical angular frequency of the grid side AC voltage, the inductance value of the grid-connected filter circuit, and the alternating-axis component of the filter inductance current is added, in the alternating-axis voltage instruction, the product of the electrical angular frequency of the grid side AC voltage, the inductance value of the grid-connected filter circuit, and the direct-axis component of the filter inductance current is subtracted, and the grid voltage direct-axis component and the alternating-axis component are introduced as feedforward signals to perform feedforward compensation on the direct-axis and alternating-axis instruction voltages.

10. The method of claim 5, wherein, The method simulates the external port characteristics of the brushless direct current motor under three fault conditions of stator resistance imbalance, open circuit fault, and inter-phase short circuit fault through a fault switching circuit (2), and is as follows: When the simulation motor is in a stator resistance imbalance fault, the first contactor is controlled to disconnect the corresponding fault phase and connect the corresponding first fault simulation resistance; When the simulation motor is in an inter-phase short circuit fault, the second contactor is controlled to close the corresponding fault phase and connect the second fault simulation resistance between the corresponding two fault phases; When the simulation motor is in an open circuit fault, the third contactor is controlled to disconnect the corresponding fault phase.

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