A brushless dc motor simulator system and method

Abstract

The application relates to a brushless direct current motor simulator system and method, which comprises a motor simulator unit and an energy feedback unit; in the motor simulator unit, a motor solution model calculates output three-phase current as a command current based on input line voltage and load torque instruction; a motor simulator unit controller takes the interface input side phase current as a tracking current, adopts a current tracking control strategy based on dynamic current deviation compensation to obtain a command voltage, and drives a motor simulation power converter; in the energy feedback unit, a phase angle of a power grid is obtained by a phase-locked loop based on alternating current side voltage and current; an energy feedback unit controller adopts a direct current side voltage control strategy based on power grid voltage orientation to generate a command voltage, and drives an energy feedback power converter. Compared with the prior art, the application can accurately simulate the square wave current and trapezoidal wave back electromotive force of the brushless direct current motor and the external port characteristics under normal operation and fault conditions of the brushless direct current motor.

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 improved brushless DC 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 the document number 10.1109 / IECON.2017.8216356, but this scheme cannot simulate the trapezoidal back EMF of the target motor.

[0007] In the document with the document 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 the 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 DC motor simulator system and a control method thereof.

[0009] The purpose of the present application can be achieved by the following technical solutions:

[0010] As a first aspect of the present application, a brushless DC motor simulator system is provided, which comprises a motor simulator unit and an energy feedback unit;

[0011] 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;

[0012] The input side of the motor solving model is connected with a 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 and outputs three-phase current as the command current of the motor simulator unit controller based on the line voltage and the load torque command, while outputting physical quantities including Hall signals for closed-loop control of the motor driver and monitoring of the motor operating state;

[0013] 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;

[0014] 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 feeds back energy of the motor simulator unit to a three-phase power grid through the grid-connected filter circuit; 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;

[0015] 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 grid phase angle; the energy feedback unit controller adopts a direct current side voltage control strategy based on grid voltage orientation to generate an instruction voltage, converts the instruction voltage through the 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.

[0016] As a preferred technical solution, the motor simulator power converter includes a T-type three-level PWM rectifier, the T-type three-level PWM rectifier is composed of three-phase bridge arms and a direct current side capacitor;

[0017] The direct current side is composed of two symmetrically distributed capacitors to form a voltage division capacitor group for providing a stable midpoint potential;

[0018] Each phase bridge arm includes two main power switching tubes and two intermediate auxiliary power switching tubes, 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, the intermediate auxiliary power switching tubes are connected in back-to-back to the midpoint of the voltage division capacitor group, and are used to realize switching between an output voltage level and a direct current midpoint, so that three levels of each phase output are realized.

[0019] As a preferred technical solution, the fault switching circuit is composed of contactors and fault resistors;

[0020] A first fault simulation resistor is connected in series on each fault phase, each first fault simulation resistor is connected in parallel with a first contactor, and is used to simulate a stator resistance imbalance fault of the motor;

[0021] A second fault simulation resistor is connected between two fault phases, each second fault simulation resistor is connected in series with a second contactor, and is used to simulate a phase-to-phase short circuit fault of the motor;

[0022] A third contactor is arranged on each fault phase to control the fault phase breaking, which is used to simulate the open circuit fault of the motor.

[0023] As a preferred technical solution, 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 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 freewheeling diode; the DC side is connected to the positive and negative bus through an energy storage capacitor; and the three-phase AC side output end is connected to a three-phase power grid through a filtering circuit.

[0024] As a second aspect of the present application, a brushless DC motor simulation method is provided, which is based on the brushless DC motor simulator system as described above, and the specific steps are as follows:

[0025] The motor simulator unit adopts a current tracking control strategy based on dynamic current deviation compensation, solves the motor simulator command voltage through the discrete current prediction equation of the target motor and the motor simulator, compensates the command voltage according to the deviation between the tracking current effective value and the command current effective value, and generates a switching signal to control the motor simulation power converter through a modulation algorithm;

[0026] The energy feedback unit adopts a direct current side voltage control strategy based on grid voltage orientation, the voltage outer ring takes the DC 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 a 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; a switching signal is generated to control the energy feedback power converter through a modulation algorithm.

[0027] As a preferred technical solution, the current tracking control strategy based on dynamic current deviation compensation is as follows:

[0028] The motor drive output side line voltage is sampled and used 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 Hall signal and the back electromotive force of the motor are output;

[0029] 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 solved;

[0030] The phase current at the input side of the interface filtering circuit is sampled as the tracking current;

[0031] 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;

[0032] The compensation voltage is used to modify the preliminary instruction voltage in combination with the Hall signal to obtain a final instruction voltage, and a modulation algorithm is used to generate a switching signal of a motor analog power converter.

[0033] As a preferred technical solution, the compensation voltage is obtained as follows for different operating states of the motor:

[0034] When the analog motor is in a normal state, direct current equivalent currents of the instruction current and the tracking current are constructed in combination with the Hall signal, effective values of the direct current equivalent currents of the instruction 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;

[0035] When the analog motor is in a fault state, effective values of the three-phase instruction 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.

[0036] As a preferred technical solution, the direct current side voltage control strategy based on grid voltage orientation is as follows:

[0037] 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;

[0038] 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;

[0039] 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;

[0040] For the generated alternating and direct-axis instruction voltages, cross-coupling compensation and grid voltage feedforward are introduced to realize decoupling control.

[0041] The compensated instruction voltage is coordinate-reverse-transformed based on the grid phase angle obtained through the phase-locked loop to obtain an instruction voltage in a synchronous stationary coordinate system, and a modulation algorithm is used to generate a switching signal of an energy feedback power converter.

[0042] As a preferred technical solution, the cross-coupling compensation and grid voltage feedforward are as follows:

[0043] In the direct axis voltage instruction, the product of the electrical angular frequency of the grid side alternating voltage, the inductance value of the grid connection filter circuit and the filter inductance current decomposed into the direct axis component is added, and the product of the electrical angular frequency of the grid side alternating voltage, the inductance value of the grid connection filter circuit and the filter inductance current decomposed into the cross axis component is subtracted in the cross axis voltage instruction, and the direct axis component and the cross axis component of the grid voltage are introduced as feedforward signals to feedforward compensate the direct axis and cross axis instruction voltages respectively.

[0044] As a preferred technical solution, the method simulates the external port characteristics of the brushless DC motor under three fault conditions of stator resistance imbalance, open circuit fault and inter-phase short circuit fault through a fault switching circuit, and specifically as follows:

[0045] When simulating the motor in the stator resistance imbalance fault, the first contactor is controlled to disconnect the corresponding fault phase and access the corresponding first fault simulation resistance;

[0046] When simulating the motor in the inter-phase short circuit fault, the second contactor is controlled to close the corresponding fault phase and access the second fault simulation resistance between the corresponding two fault phases;

[0047] When simulating the motor in the open circuit fault, the third contactor is controlled to disconnect the corresponding fault phase.

[0048] Compared with the prior art, the present application has the following beneficial effects:

[0049] 1) The power stage conversion device of the brushless DC motor simulator adopted in 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, and can provide different load conditions for different test requirements, can simulate the electrical external port characteristics of the motor under different 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 can withstand high voltage and large current during actual system operation can be tested.

[0050] 2) The current tracking control strategy based on dynamic current deviation compensation adopted in the present application has the ability to simulate the square wave current and trapezoidal back electromotive force of the target brushless DC motor, solving the problems of insufficient square wave current tracking accuracy and difficulty in simulating trapezoidal back electromotive force in the prior art.

[0051] 3) The topology structure of three-level PWM rectifier + two-level PWM inverter adopted in the present application can simulate the trapezoidal back electromotive force of the brushless DC 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 grid, and realize green energy saving of the test.

[0052] 4) The application can simulate the external port characteristics of the brushless DC motor stator resistance imbalance, open circuit fault, and interphase short circuit fault, and solve the problem that the traditional electric drive test platform cannot realize motor fault test.

[0053] 5) The motor solving model in the application is based on the FPGA real-time operation unit, meets the requirements of high precision and high real-time of the motor solving model, the motor simulator unit controller and the energy feedback unit controller are based on the DSP embedded digital control chip, meet the requirements of microsecond level response of the motor simulator to the control link, and can realize real-time monitoring of motor parameter setting, working condition setting and key state quantity of the motor. BRIEF DESCRIPTION OF DRAWINGS

[0054] Figure 1 It is the overall structure schematic diagram of the brushless DC motor simulator system of the application.

[0055] Figure 2 It is the motor simulation power converter topology structure diagram in the embodiment.

[0056] Figure 3 It is the control strategy control block diagram of the motor simulator unit under the normal state of the simulated motor in the embodiment.

[0057] Figure 4 It is the control strategy control block diagram of the motor simulator unit under the fault state of the simulated motor in the embodiment.

[0058] Figure 5 It is the energy feedback power converter topology structure diagram in the embodiment.

[0059] Figure 6 It is the control strategy control block diagram of the energy feedback unit in the embodiment.

[0060] Figure 7 It is the phase-locked loop schematic diagram adopted by the control system of the energy feedback unit in the embodiment.

[0061] Figure 8 It is the fault switching circuit topology structure diagram of the motor simulator unit in the embodiment.

[0062] Figure 9 , Figure 10 It is the motor simulator port characteristic test result under the steady state working condition one in the embodiment.

[0063] Figure 11 , Figure 12 It is the motor simulator port characteristic test result under the steady state working condition two in the embodiment.

[0064] Figure 13 It is the motor simulator port characteristic test result under the dynamic working condition in the embodiment.

[0065] The figure shows: 1, motor analog power converter, 2, fault switching circuit, 3, interface filter circuit, 4, driver output side line voltage sampling circuit, 5, motor solution model, 6, motor simulator unit controller, 7, interface filter circuit input side phase current sampling circuit, 8, motor simulator unit PWM drive circuit, 9, energy feedback power converter, 10, grid-connected filter circuit, 11, energy feedback unit DC side voltage sampling circuit, 12, energy feedback unit controller, 13, phase-locked loop, 14, energy feedback unit AC side voltage and current sampling circuit, 15, energy feedback unit PWM drive circuit, 16, motor parameter setting, working condition setting and running state monitoring module. DETAILED DESCRIPTION

[0066] The application will be described in detail below in combination with the drawings and specific embodiments. The embodiments are implemented on the premise of the technical scheme of the application, and detailed implementation and specific operation processes are given, but the protection scope of the application is not limited to the following embodiments.

[0067] The application relates to a brushless DC motor simulator system for a CMG high-speed rotor, as shown in the figure. Figure 1 The brushless DC motor simulator system comprises a motor simulator unit and an energy feedback unit.

[0068] The main circuit of the motor simulator unit comprises a motor analog 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 solution model 5, a motor simulator unit controller 6 and a motor simulator unit PWM drive circuit 8.

[0069] 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 running state monitoring module 16 is connected to the motor simulator unit and the energy feedback unit respectively.

[0070] The fault switching circuit 2 is connected with the motor driver on the input side, the output side of the fault switching circuit 2 is connected with the input side of the interface filter circuit 3, the output side of the interface filter circuit 3 is connected with the input side of the motor analog power converter 1, the motor calculation model 5, the motor analog unit controller 6 and the motor analog unit PWM drive circuit 8 are connected in sequence, the energy feedback power converter 9 and the grid-connected filter circuit 10 are connected, the phase-locked loop 13, the energy feedback unit controller 12 and the energy feedback unit PWM drive circuit 15 are connected in sequence.

[0071] Further, the motor analog power converter 1 topology structure is as shown in Figure 2 , which is a T-type three-level PWM rectifier topology structure composed of three-phase bridge arm structure and DC side capacitor. The three-phase bridge arms are A phase, B phase and C phase, and each phase bridge arm is composed of two main power switch tubes and two intermediate auxiliary switch tubes, which are , , , of A phase, , , , of B phase, , , , of C phase, wherein the upper and lower bridge arm main power switch tubes are used to connect the DC bus, the intermediate auxiliary switch tubes are connected in back-to-back, 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.

[0072] Further, the motor analog 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 as 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 solved , , , wherein the command current , , and the tracking current , , are all low-pass filtered. On this basis, dynamic current deviation compensation is further introduced, and is processed according to the running state of the motor. When the analog motor is in a normal state, the direct current equivalent currents of the command current and the tracking current are constructed respectively in combination with the Hall signal, and the effective values of the two are calculated respectively by using a sliding window effective value calculation module, and the difference between the effective values is sent to a PI regulator to obtain a compensation voltage ; when the analog motor is in a fault state, the effective values of the three-phase command current and the tracking current are calculated respectively, and the difference between the effective values is sent to a PI regulator to obtain three-phase compensation voltages . Finally, the compensation voltage is used in combination with the Hall signal to correct the preliminary command voltage to obtain the final command voltage 、 、 , and the switching signal of the motor analog power converter 1 is generated through an SVPWM modulation algorithm.

[0073] Further, the energy feedback power converter 9 topology structure is 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 being and for the A phase, being and for the B phase, and being and for the C phase, and each power tube being connected in parallel with a reverse freewheeling diode. The positive and negative bus bars are connected through an energy storage capacitor to provide a stable DC voltage for the converter. The three-phase AC side output terminals of the converter are connected to the grid three-phase after a filtering circuit.

[0074] Further, the energy feedback unit controller 12 and the phase-locked loop 13 are both based on a DSP embedded digital control chip, and adopt a direct current side voltage control strategy based on grid voltage orientation, and the control block diagram is shown in Figure 6 . First, the grid voltage is sampled and the grid phase angle is extracted through the phase-locked loop 13, so as to establish a rotating coordinate system synchronized with the grid voltage, and the schematic diagram of the phase-locked loop 13 is shown in Figure 7 . In this coordinate system, the grid voltage is decomposed into a direct-axis component and a quadrature-axis component , and the filter inductance current is decomposed into a direct-axis component and a quadrature-axis component . The voltage outer loop takes the DC side bus voltage as the control object, compares the reference voltage with the actual voltage , and outputs a direct-axis reference current , to realize the stability of the DC side voltage of the energy feedback unit. The quadrature axis reference current is set to zero, i.e. , to realize the unity power factor of the energy feedback unit. The current inner loop takes current tracking as the target, and the reference current , is compared with the actual current , to generate the instruction voltage , , to overcome the cross coupling caused by the inductance parameter, the term is compensated in the direct axis voltage instruction, and the term is compensated in the quadrature axis voltage instruction, while the grid voltage components and are introduced as feedforward signals to realize the decoupling control of the current loop. Wherein, is the electrical angular frequency of the grid-side AC voltage, L is the inductance value of the grid filter circuit. Finally, the instruction voltage is obtained after coordinate inverse transformation, i.e. , , and the switching signal of the energy feedback power converter 9 is generated through the SVPWM modulation algorithm.

[0075] Further, the fault switching circuit 2 topology is shown in Figure 8 , which is composed of nine contactors and six fault resistors, and can be used to simulate the stator resistance imbalance fault, inter-phase short circuit fault and open circuit fault of the brushless DC motor. The contactor ~ controls the fault resistance in series in the fault phase , , to simulate the stator resistance imbalance fault of the motor, the contactor ~ controls the fault resistance connected between the fault two phases , , to simulate the inter-phase short circuit fault of the motor, and the contactor ~ controls the fault phase circuit to simulate the open circuit fault of the motor. The contactor ~ is normally closed, the contactor ~ is normally open, and the contactor ~ is normally closed.

[0076] 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 instruction 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 instruction 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.

[0077] Further, the motor simulator unit controller 6 and the energy feedback unit controller 12 both select the TMS320F28335 type DSP embedded digital control chip of Texas Instruments Company as the main control 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 model-based design idea (Mode Based Design, MBD), and the embedded C code is generated by using the Matlab / Simulink automatic code generation technology.

[0078] Further, the motor calculation model 5 is based on the FPGA real-time operation unit and can realize microsecond-level time step simulation, so as to meet the requirements of high precision and high real-time of the motor calculation model. The motor calculation model includes the voltage equation, the torque equation and the motion equation of the motor, and the motor parameters include the stator winding resistance, the phase inductance, the moment of inertia, the torque coefficient and the like. The motor calculation model 5 can also use the finite element motor model based on the finite element lookup table, which is used to consider the nonlinear problems caused by the magnetic core saturation, high-order harmonic, slotting effect and the like. The model takes the port voltage and the load torque as the input, calculates the motor current in real time as the instruction current of the motor simulator unit, and calculates the back electromotive force as the calculation variable in the motor simulator control strategy to provide the reference information of the back electromotive force simulation. In addition, the motor calculation model 5 can also calculate the virtual speed, the virtual electromagnetic torque, the Hall signal, the virtual angle position and the like, so as to realize the closed-loop control of the motor driver and the motor operation state monitoring.

[0079] The brushless direct current motor simulator system of the application works in the following way:

[0080] The motor simulator unit control system firstly samples the motor driver output side line voltage sampling circuit 4 、 、 , and sends it to the FPGA real-time operation unit of the motor calculation model 5, and the load torque instruction T Ltogether as the input of the motor calculation model 5. The motor calculation model 5 calculates three-phase currents , , as the instruction current of the motor simulator unit. At the same time, the motor calculation 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 back electromotive force of the motor simulator. In addition, the motor calculation model 5 outputs physical quantities such as the virtual speed, virtual torque, rotor angle position, and Hall signal of the motor, which are used for closed-loop control of the motor driver and monitoring of the operating state of the motor. Then, the interface filter circuit samples the input side phase current to obtain the tracking current , , . The discrete current prediction equation is obtained by combining the mathematical models of the target motor and the motor simulator, the instruction voltage is solved, and the instruction voltage is compensated according to the deviation between the effective value of the tracking current and the effective value of the instruction current. 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 instruction current output by the motor calculation model 5 of the motor simulator unit, so as to complete the simulation of the electrical characteristics of the port of the target motor. On the other hand, the energy feedback unit control system first samples the grid-connected voltage and extracts the phase angle through the phase-locked loop 13 , so as to establish a rotating coordinate system synchronized with the grid. The voltage outer loop takes the DC side bus voltage as the control object, outputs the direct-axis reference current, and sets the quadrature-axis reference current to zero to realize the unit 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 instruction voltage , , and the grid voltage feedforward and cross-coupling compensation are introduced, so as to realize the decoupling control of the direct-axis and quadrature-axis currents, thereby obtaining the direct-axis and quadrature-axis voltage instructions, and generating the switching signal of the energy feedback power converter 9 through the SVPWM modulation algorithm, so as to realize the energy feedback of the energy feedback unit 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.

[0081] Further, in the present embodiment, when the simulated motor is in a stator resistance imbalance fault, the contactors ~ are controlled to be disconnected for the corresponding fault phase, and the fault resistance is connected , , . When the simulated motor is in an inter-phase short circuit fault, the contactors ~ are controlled to be closed for the corresponding fault phase, and the fault resistance is connected , , . When the simulated motor is in an open circuit fault, the contactors ~ disconnection of the corresponding faulty phase.

[0082] The specific working procedure of the motor simulator unit of the brushless DC motor simulator system is as follows:

[0083] 1.1) Obtain the voltage on the output side of the motor driver as the input of the motor calculation model, and solve the motor current, Hall signal, etc. The solved current is the command current of the motor simulator unit;

[0084] 1.2) Sample the phase current on the input side of the interface filter circuit and compare it with the command current, and obtain the control signals of the switches of the motor simulation power converter through the motor simulator unit controller;

[0085] 1.3) Convert the PWM control signal into the PWM drive signal of the switch of the motor simulation power converter through the PWM drive circuit of the motor simulator unit, and then realize the turn-on and turn-off of the switch, so that the motor simulator unit has the same external port characteristics as the target motor.

[0086] The specific working procedure of the energy feedback unit is as follows:

[0087] 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 electrical angle of the energy feedback unit controller through the phase-locked loop;

[0088] 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 outputs the control signals of the switches of the energy feedback power converter with the unit power factor as the control target and the electrical angle obtained through the phase-locked loop;

[0089] 2.3) Convert the PWM control signal 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 realize the turn-on and turn-off of the switch, so that the energy feedback unit can feedback energy to the grid with high power factor and low harmonic content, while maintaining the stability of the DC side voltage of the energy feedback unit.

[0090] Embodiment 2

[0091] As one of the specific embodiments of the present application, this embodiment is verified by simulation method. The verification environment is as follows: under the same test conditions, the motor driver adopts a closed-loop operation mode to provide driving input for the motor simulator, and tests and verifies under different working conditions, and compares with the operating state quantity of the target motor.

[0092] The target motor simulated in this embodiment is a brushless DC motor with 8 pole pairs, the phase inductance of the motor is 15 , the phase resistance of the motor is 0.3 , the torque constant is 0.025 , 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 DC motor simulator.

[0093] Verification condition one: the speed is 5000 r / min, and the load is 0.05 . The test results are shown in Figure 9 , Figure 10 , in window one Figure 9 , the A-phase tracking current of the motor simulator is , the A-phase command current of the motor simulator is , in window two , the A-phase tracking current of the motor simulator is , the A-phase current of the target motor is , in window three , the virtual speed of the motor simulator is , the virtual electromagnetic torque of the motor simulator is , the electromagnetic torque of the target motor is Figure 10 , in window one , the A-phase terminal voltage of the target motor is , the A-phase terminal voltage of the motor simulator is . The 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 conditions.

[0094] Verification condition two: the speed is 9000 r / min, and the load is 0.05 Figure 11 . The test results are shown in Figure 12 , Figure 11 , in window one , the A-phase tracking current of the motor simulator is , the A-phase command current of the motor simulator is , in window two , the A-phase tracking current of the motor simulator is For the virtual speed of the motor simulator, For the target motor speed, in window four For the virtual electromagnetic torque of the motor simulator, The target is the electromagnetic torque of the motor. Figure 12 In Window 1 For the target motor A-phase terminal voltage, in window two The voltage at phase A of the motor simulator is shown. Test results demonstrate that the proposed control strategy exhibits excellent steady-state performance and can effectively simulate the external port characteristics of a brushless DC motor under steady-state operating conditions.

[0095] Verification condition 3: Speed ​​is 9000 r / min, load is 0.02 Cut to 0.05 The test results are as follows Figure 13 As shown in window one For tracking the current of phase A in the motor simulator, For the A-phase command current of the motor simulator, in window two For tracking the current of phase A in the motor simulator, For the target motor A-phase current, in window three For the virtual speed of the motor simulator, For the target motor speed, in window four For the virtual electromagnetic torque of the motor simulator, The target is the electromagnetic torque of the motor. Test results show that the proposed control strategy has good dynamic performance and can effectively simulate the external port characteristics of a brushless DC motor under dynamic operating conditions.

[0096] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection 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.

Images