A dual three-phase permanent magnet synchronous motor voltage stabilization control method based on capacitance current compensation

Abstract

The application relates to the technical field of aviation motors and discloses a dual three-phase permanent magnet synchronous motor voltage stabilization control method based on capacitor current compensation, which comprises the following steps: S1, decoupling two sets of three-phase windings of a dual three-phase permanent magnet synchronous motor to obtain a mathematical model of the dual three-phase motor; S2, determining initial controller parameters of a voltage outer loop and a current inner loop based on the mathematical model, and setting a compensation coefficient; S3, collecting the voltage of a direct-current bus in real time and calculating capacitor current values of the direct-current bus; and S4, obtaining a compensation amount of a q-axis current instruction according to the compensation coefficient and the capacitor current values of the direct-current bus voltage. The dual three-phase permanent magnet synchronous motor voltage stabilization control method based on capacitor current compensation reflects the instantaneous change of a load according to the sudden change of the capacitor current values of the direct-current bus, and then uses the capacitor current values to compensate the current instruction of the current inner loop, so that the current instruction is more rapid, and the dynamic response of the system is accelerated.

Description

Technical Field

[0001] This invention relates to the field of aviation motor technology, and in particular to a voltage regulation control method for a dual three-phase permanent magnet synchronous motor based on capacitor current compensation. Background Technology

[0002] In addition to the advantages of ordinary three-phase permanent magnet synchronous motors, such as high efficiency and energy saving, high power density, simple structure and high reliability, dual three-phase permanent magnet synchronous motors can also output high power using low-voltage power electronic devices. Moreover, the structure of two sets of windings facilitates fault-tolerant control. It has broad prospects in the aviation field and has been extensively studied. It is suitable for use as an aircraft starter generator.

[0003] When used as a starter generator, the dual three-phase permanent magnet synchronous motor has two operating modes: starting and generating. In starting mode, the motor acts as an electric motor, driving the aircraft engine to ignition speed and then maintaining positive torque to provide power for a smooth start-up of the aircraft. In generating mode, the motor acts as a generator, providing electrical energy to airborne equipment through voltage regulation control.

[0004] In terms of voltage regulation control, dual three-phase permanent magnet synchronous motors differ from electrically excited motors. Their rotor magnetic field is generated by permanent magnets, which is difficult to adjust, requiring a rectifier and voltage regulator to output a stable DC voltage. PWM controllable rectification enables bidirectional power transmission and provides high-quality control of the output DC voltage, making it the most popular rectification method currently. For the control strategy of the PWM rectifier, a field-oriented (FOC) vector control strategy can be selected.

[0005] Traditional vector control strategies consist of three parts: an outer voltage loop, an inner current loop, and an SVPWM (Single-Voltage Width Modulation) component. The outer voltage loop compares the measured DC bus voltage with a setpoint, uses PI control to minimize the voltage error, and then outputs the current command for the inner current loop via negative feedback. This current command is then processed by the inner current loop's PI controller and SVPWM to generate the final rectifier PWM signal, achieving voltage regulation and stabilizing the bus voltage at the setpoint. However, traditional dual-loop vector control methods suffer from insufficient dynamic response and large DC bus voltage fluctuations during load abrupt changes. This is because, during load abrupt changes, the outer voltage loop only changes the current command when the detected actual DC bus voltage deviates from the reference DC voltage. However, due to the DC bus capacitance, the DC voltage does not change abruptly. This prevents the outer voltage loop from generating a fast and effective current command to offset the load disturbance, leading to a decrease in control performance. Summary of the Invention

[0006] In view of this, the present invention proposes a voltage regulation control method for a dual three-phase permanent magnet synchronous motor based on capacitor current compensation. According to the sudden change of the DC bus capacitor current value, the instantaneous change of the load is reflected, and then the capacitor current value is used to compensate the current command of the inner current loop, making the current command faster and thus accelerating the dynamic response of the system.

[0007] The technical solution of this invention is implemented as follows: This invention provides a voltage regulation control method for a dual three-phase permanent magnet synchronous motor based on capacitor current compensation, comprising the following steps:

[0008] S1 decouples the two sets of three-phase windings of the dual three-phase permanent magnet synchronous motor to obtain the mathematical model of the dual three-phase motor.

[0009] S2 uses a mathematical model to determine the initial controller parameters for the voltage outer loop and the current inner loop, and sets the compensation coefficients.

[0010] S3 collects the voltage of the DC bus in real time and calculates the capacitance current value of the DC bus.

[0011] S4 obtains the compensation amount of the q-axis current command based on the compensation coefficient and the capacitor current value of the DC bus voltage.

[0012] S5 determines the transfer function of the voltage outer loop after adding capacitor current compensation based on the compensation amount of the q-axis current command.

[0013] S6 adjusts the initial controller parameters of the voltage outer loop based on the transfer function after adding capacitor current compensation, and obtains the final controller parameters of the voltage outer loop. The motor is then regulated and controlled using the final controller parameters of the voltage outer loop.

[0014] Based on the above technical solution, preferably, in step S1, the mathematical model includes voltage equation, flux linkage equation, and torque equation, wherein the voltage equation, flux linkage equation, and torque equation are respectively:

[0015]

[0016] Among them, u d1 u d2 u q1 u q2 These are the dq-axis voltages of the two windings, i d1 i d2 i q1 i q2 These are the dq-axis currents of the two sets of windings, respectively. The dq axis flux linkages are two sets of windings, ω e The electric angular velocity of the motor. For permanent magnet flux linkage, L d L qFor the dq axis inductance, L dd L qq For the d-axis mutual inductance and q-axis mutual inductance between the two sets of windings, T e denoted as the electromagnetic torque of the motor, and p as the number of pole pairs of the motor.

[0017] Based on the above technical solutions, preferably, step S1 includes the following steps:

[0018] S11 transforms the current of the two sets of three-phase windings of the dual three-phase permanent magnet synchronous motor into two independent dq coordinate systems;

[0019] S12 expresses the voltage equations of the two windings of the motor as independent dq-axis voltage equations in the dq coordinate system;

[0020] S13 associates the flux linkage equations of the two windings with the corresponding dq axis currents and inductance matrices, respectively, to decouple the flux linkages and obtain the mathematical model of the dual three-phase motor.

[0021] Based on the above technical solutions, preferably, step S2 includes the following steps:

[0022] S21 determines the controller parameters for the inner current loop based on the mathematical model;

[0023] S22 obtains the closed-loop transfer function of the current inner loop through the controller parameters of the current inner loop;

[0024] S23 obtains the initial controller parameters of the voltage outer loop based on the closed-loop transfer function of the inner current loop.

[0025] More preferably, in step S21, the bandwidth of the outer current loop is set to 1 / 10 of the switching frequency, and the controller parameters of the inner current loop are:

[0026]

[0027] Where, k id k pd These are the integral and proportional coefficients of the d-axis current controller, respectively, k iq k pq These are the integral and proportional coefficients of the q-axis current controller, respectively; R is the stator resistance of the motor; and T is the linear coefficient. s For the switching period, ω c This is the cutoff frequency of the inner current loop.

[0028] More preferably, in step S22, the transfer function of the inner current loop and its simplified result are:

[0029]

[0030] Where, k iS represents the integral coefficients of the d-axis and q-axis controllers of the current inner loop, and S is the complex frequency variable.

[0031] More preferably, in step S23, the initial controller parameters for the outer voltage loop are:

[0032]

[0033] Where, k i k p These are the integral and proportional coefficients of the voltage outer loop controller, ω. cu R is the voltage outer loop cutoff frequency, T is the current inner loop equivalent time constant, and R is the voltage outer loop cutoff frequency. L C is the load resistance, and C is the DC bus capacitance.

[0034] Based on the above technical solution, preferably, in step S3, the capacitance current value of the DC bus is expressed as:

[0035]

[0036] Among them, I c T is the capacitor current value. delay ΔU represents the delay time between the two voltage acquisitions, and ΔU represents the difference between the two DC bus voltage acquisitions.

[0037] Based on the above technical solution, preferably, step S2 further includes determining the value of the compensation coefficient K according to the transfer function of the load disturbance signal, wherein the transfer function of the load disturbance signal is:

[0038]

[0039] Among them, G I For the closed-loop transfer function of the inner current loop, i L U is the load current, U is the bus voltage, S is the complex frequency variable, C is the DC bus capacitance, and T is the load current. s For the switching period, k i k p These are the integral coefficient and proportional coefficient of the voltage outer loop controller, respectively.

[0040] Based on the above technical solutions, preferably, the transfer function of the voltage outer loop after adding capacitor current compensation is:

[0041]

[0042] Among them, G I Let S be the closed-loop transfer function of the inner current loop, S be the complex frequency variable, C be the DC bus capacitance, and T be the current inner loop closed-loop transfer function. s For the switching period, k p ω is the proportional coefficient of the voltage outer loop controller. cWhere is the cutoff frequency of the inner current loop, and K is the compensation coefficient.

[0043] The voltage regulation control method for dual three-phase permanent magnet synchronous motors based on capacitor current compensation of the present invention has the following advantages over the prior art:

[0044] (0) By introducing a real-time compensation mechanism for capacitor current, the dynamic response problem of traditional dual closed-loop vector control under load change is significantly improved. Compared with the traditional method, this scheme not only relies on the detection of bus voltage in the outer voltage loop, but also calculates the capacitor current of DC bus in real time and uses it as a compensation quantity to directly adjust the q-axis current command, so that the inner current loop can respond quickly to load changes. This compensation mechanism effectively reduces the large fluctuation of DC bus voltage, enhances the dynamic response capability and voltage regulation accuracy of the system, and significantly improves the control performance and stability of the system, especially under load change.

[0045] (1) The DC bus capacitance is calculated by using the difference between the two DC bus voltage acquisitions and the delay time between the two voltage acquisitions. Based on the calculation of instantaneous voltage changes, the change of capacitor current can be reflected in real time, which helps to respond quickly to the dynamic changes of the system. Furthermore, by accurately calculating the capacitor current, the accuracy of the outer loop voltage control can be effectively improved, the voltage regulation performance of the system can be enhanced, and voltage fluctuations can be reduced. Attached Figure Description

[0046] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0047] Figure 1 This is a schematic diagram illustrating the steps of the voltage regulation control method for a dual three-phase permanent magnet synchronous motor based on capacitor current compensation according to the present invention.

[0048] Figure 2 This is a block diagram of the voltage regulation control method for a dual three-phase permanent magnet synchronous motor based on capacitor current compensation according to the present invention.

[0049] Figure 3 This is a voltage outer loop block diagram of the voltage regulation control method for dual three-phase permanent magnet synchronous motors based on capacitor current compensation according to the present invention.

[0050] Figure 4 This is a current inner loop block diagram of the voltage regulation control method for dual three-phase permanent magnet synchronous motors based on capacitor current compensation according to the present invention.

[0051] Figure 5This is a schematic diagram illustrating the capacitor current calculation in the voltage regulation control method for dual three-phase permanent magnet synchronous motors based on capacitor current compensation according to the present invention.

[0052] Figure 6 This is a schematic diagram of the system response to a step change in load current in the voltage regulation control method for dual three-phase permanent magnet synchronous motors based on capacitor current compensation according to the present invention.

[0053] Figure 7 Bode plots of system transfer functions corresponding to different K values ​​for the voltage regulation control method of dual three-phase permanent magnet synchronous motor based on capacitor current compensation of the present invention;

[0054] Figure 8 This is a schematic diagram of a simulation setup embodiment of the voltage regulation control method for dual three-phase permanent magnet synchronous motors based on capacitor current compensation according to the present invention;

[0055] Figure 9 This is an example diagram comparing the capacitor current waveforms before and after compensation in the voltage regulation control method for dual three-phase permanent magnet synchronous motors based on capacitor current compensation according to the present invention.

[0056] Figure 10 This is an example diagram showing the current command waveforms before and after compensation in the voltage regulation control method for dual three-phase permanent magnet synchronous motors based on capacitor current compensation according to the present invention.

[0057] Figure 11 This is a perspective view of the voltage regulation control method for dual three-phase permanent magnet synchronous motors based on capacitor current compensation according to the present invention. Detailed Implementation

[0058] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0059] Traditional vector control rectification and voltage regulation strategies suffer from insufficient current command in the inner current loop when faced with sudden load changes, resulting in inadequate system dynamic response, large DC voltage fluctuations, and long voltage recovery times. This makes them unsuitable for applications with high power generation quality requirements, such as aircraft starter generators. Therefore, this solution proposes a voltage regulation control method for dual three-phase permanent magnet synchronous motors based on capacitor current compensation. By reflecting the instantaneous changes in the load based on the sudden changes in the DC bus capacitor current value, the capacitor current value is used to compensate for the current command in the inner current loop, making the current command more rapid and thus accelerating the system's dynamic response.

[0060] like Figure 1-7As shown, the voltage regulation control method for dual three-phase permanent magnet synchronous motors based on capacitor current compensation of the present invention specifically includes steps S1-S6.

[0061] Step S1: Decouple the two sets of three-phase windings of the dual three-phase permanent magnet synchronous motor to obtain the mathematical model of the dual three-phase motor.

[0062] The two windings of a dual three-phase motor are coupled. To achieve better control, it is necessary to decouple the two windings. Existing decoupling methods include dual dq decoupling and vector space decoupling. In this embodiment, the dual dq decoupling method is used. Coordinate transformations are performed on the two three-phase windings of the dual three-phase permanent magnet synchronous motor to obtain the equivalent mathematical model of the decoupled dual three-phase motor, which includes voltage equations, flux linkage equations, and torque equations. The voltage equations, flux linkage equations, and torque equations are as follows:

[0063]

[0064] Among them, u d1 u d2 u q1 u q2 These are the dq-axis voltages of the two windings, i d1 i d2 i q1 i q2 These are the dq-axis currents of the two sets of windings, respectively. The dq axis flux linkages are two sets of windings, ω e The electric angular velocity of the motor. For permanent magnet flux linkage, L d L q For the dq axis inductance, L dd L qq For the d-axis mutual inductance and q-axis mutual inductance between the two sets of windings, T e denoted as the electromagnetic torque of the motor, and p as the number of pole pairs of the motor.

[0065] The dual dq decoupling method is a commonly used decoupling technique in the control of dual three-phase permanent magnet synchronous motors. It mainly achieves decoupling control of the motor by transforming the coordinates of the currents of the two sets of three-phase windings. Specifically, it can be carried out using steps S11-S13.

[0066] Step S11: Transform the currents of the two sets of three-phase windings of the dual three-phase permanent magnet synchronous motor into two independent dq coordinate systems.

[0067] The dual dq decoupling method first introduces two independent dq coordinate systems, used to describe the two sets of three-phase windings of a dual three-phase permanent magnet synchronous motor. These two dq coordinate systems are typically chosen based on the motor rotor flux linkage, which allows the AC component of the stator current to be converted into a DC component, facilitating control.

[0068] Then, through dq transformation, the two sets of three-phase stator currents are transformed into two independent dq coordinate systems.

[0069] Step S12: In the dq coordinate system, express the voltage equations of the two sets of windings of the motor as independent dq-axis voltage equations.

[0070] This allows for separate control of the voltage of each winding, thus achieving initial decoupling. In the dq coordinate system, the voltage equation is expressed as dq-axis components in an independent manner, which can be controlled separately to adjust the voltage of the two windings independently, reducing the coupling effect between them.

[0071] Step S13: Associate the flux linkage equations of the two sets of windings with the corresponding dq axis currents and inductance matrices respectively, and decouple the flux linkages to obtain the mathematical model of the dual three-phase motor.

[0072] For each winding, the flux linkage can be expressed as the product of the current and the inductance matrix. In actual motors, there is a certain mutual inductance between the two windings, which causes the flux linkage equations to affect each other. By decoupling the dq current and flux linkage, the torque equation is established, and independent control of the total electromagnetic torque is achieved.

[0073] Step S2: Based on the mathematical model, determine the initial controller parameters for the voltage outer loop and the current inner loop, and set the compensation coefficients.

[0074] Based on the mathematical model of a dual three-phase motor, controlling the q-axis current controls the motor torque, and controlling the d-axis current controls the motor magnetic field. Building upon this, a voltage outer loop can be set. First, the actual DC voltage value is sampled and compared with a set DC voltage reference value to obtain the voltage error. This voltage error is then input to the PI controller in the voltage outer loop for adjustment. The output of the PI controller serves as the q-axis current setpoint for the current inner loop, further controlling the motor torque.

[0075] In the inner current loop, the d-axis current reference value is fixed to 0. This is because the d-axis current primarily affects the motor's magnetic field, and under this control strategy, the magnetic field remains constant to simplify the control process. The main task of the inner current loop is to control the q-axis current. The q-axis current setpoint generated by the outer voltage loop is used as the target value for the inner current loop. The actual q-axis current is adjusted by a PI controller to accurately track the target value, thereby controlling the motor's torque output. It is important to ensure that the setpoints for the d- and q-axis currents of both windings are always identical, ensuring that the d-axis and q-axis controls of the motor are independent and avoiding cross-interference, thus achieving effective decoupling control.

[0076] For the inner current loop and the outer voltage loop, without adding capacitor current compensation, the initial controller parameters are obtained through steps S21-S23. These parameters are then modified and adjusted during current compensation to achieve voltage regulation control.

[0077] Step S21: Determine the controller parameters for the inner current loop based on the mathematical model.

[0078] The selection of parameters for the current inner loop controller needs to consider bandwidth, phase margin, and dynamic performance. The bandwidth of the current inner loop is usually set high to ensure that the current can respond quickly to external changes. The phase margin is used to ensure the stability of the system. Dynamic performance can balance response speed and system stability, which is achieved by selecting appropriate proportional and integral gains.

[0079] In one specific embodiment, the bandwidth of the outer current loop is set to 1 / 10 of the switching frequency, then the controller parameters of the inner current loop are:

[0080]

[0081] Where, k id k pd These are the integral and proportional coefficients of the d-axis current controller, respectively, k iq k pq These are the integral and proportional coefficients of the q-axis current controller, respectively; R is the stator resistance of the motor; and T is the linear coefficient. s For the switching period, ω c This is the cutoff frequency of the inner current loop.

[0082] Step S22: Obtain the closed-loop transfer function of the current inner loop using the controller parameters of the current inner loop.

[0083] Based on the mathematical model of the motor and the parameters of the designed PI controller, the open-loop transfer function of the current inner loop can be obtained. Then, by substituting the open-loop transfer function into the derivation formula of the closed-loop transfer function, the closed-loop transfer function of the current inner loop can be obtained.

[0084] Based on the controller parameters of the aforementioned inner current loop, the closed-loop transfer function of the inner current loop and its simplified result can be obtained as follows:

[0085]

[0086] Where, k i S represents the integral coefficients of the d-axis and q-axis controllers of the current inner loop, and S is the complex frequency variable.

[0087] This closed-loop transfer function describes the response characteristics of the actual current under a given current reference value.

[0088] Step S23: Obtain the initial controller parameters of the voltage outer loop based on the closed-loop transfer function of the inner current loop.

[0089] The main objective of the outer voltage loop is to control the DC bus voltage and stabilize it at a set value by adjusting the q-axis current reference value of the inner current loop. The closed-loop transfer function of the current loop describes the dynamic behavior of the current loop and can be used to analyze the response time and stability of the current loop.

[0090] The bandwidth of the voltage outer loop needs to be selected according to the actual DC voltage requirements. The initial controller parameters of the voltage outer loop can be set according to the simplified current loop transfer function.

[0091] Based on the aforementioned closed-loop transfer function for the inner current loop, the initial controller parameters for the outer voltage loop are set as follows:

[0092]

[0093] Where, k i k p These are the integral and proportional coefficients of the voltage outer loop controller, ω. cu R is the voltage outer loop cutoff frequency, T is the current inner loop equivalent time constant, and R is the voltage outer loop cutoff frequency. L C is the load resistance, and C is the DC bus capacitance.

[0094] It should be noted that if the voltage outer loop controller alone cannot generate a fast and effective current command, a capacitor current compensation stage is added. First, the capacitor current value must be obtained, and then the compensation coefficient K is introduced.

[0095] like Figure 6 As shown, in this embodiment, the compensation coefficient K needs to be set. The specific value of the compensation coefficient K needs to be determined according to the actual system conditions. Specifically, the value of the compensation coefficient K can be determined through the transfer function of the load disturbance signal. The transfer function of the load disturbance signal is:

[0096]

[0097] Among them, G I For the closed-loop transfer function of the inner current loop, i L U is the load current, U is the bus voltage, S is the complex frequency variable, C is the DC bus capacitance, and T is the load current. s For the switching period, k i k p These are the integral coefficient and proportional coefficient of the voltage outer loop controller, respectively.

[0098] As shown in the figure, the system's anti-disturbance capability under different K values ​​is calculated based on the transfer function of the load disturbance signal, and then the appropriate compensation coefficient K value is determined according to the actual voltage requirements.

[0099] Step S3: Real-time acquisition of the DC bus voltage and calculation of the DC bus capacitance current value.

[0100] There is generally no current sensor on the DC bus capacitor. The capacitor current value needs to be calculated from the DC bus voltage using the capacitor current formula.

[0101] like Figure 5 As shown, the capacitance current value of the DC bus is expressed as:

[0102]

[0103] Among them, I c T is the capacitor current value. delay ΔU represents the delay time between the two voltage acquisitions, and ΔU represents the difference between the two DC bus voltage acquisitions.

[0104] Since the capacitor current is reactive current, if T delay If the selected value is too small, the calculated current will fluctuate greatly, causing voltage fluctuations after compensation; if T... delay If the chosen value is too large, it will be unable to reflect load changes instantaneously and will not be able to accelerate the system's dynamic response. Therefore, an appropriate T value needs to be selected based on the actual response speed of the outer voltage loop. delay Value. Note T. delay The current cannot exceed the time T required for the current command to reach the desired command without capacitor current compensation. If the capacitor current is negative, it indicates capacitor discharge, a drop in DC bus voltage, and a sudden load change. According to the power expression for a dual three-phase permanent magnet synchronous motor... (ω) m (where q is the mechanical angular velocity). In this case, the q-axis current setpoint needs to be increased to increase the motor output power, thereby raising the DC bus voltage. Similarly, if the capacitor current is positive, it means that the capacitor is charging and the DC bus voltage is rising. The load change is a sudden unloading. In this case, the q-axis current setpoint needs to be decreased to reduce the motor output power, thereby reducing the DC bus voltage.

[0105] Step S4: Obtain the compensation amount of the q-axis current command based on the compensation coefficient and the capacitor current value of the DC bus voltage.

[0106] Using the compensation coefficient in step S2 and the capacitor current value calculated in step S3, the compensation amount of the q-axis current command is calculated. This compensation amount is used to adjust the q-axis current reference value to cope with the fluctuation of DC bus voltage.

[0107] Specifically, the compensation amount is obtained by multiplying the capacitor current value by the compensation coefficient K, and then subtracting the compensation amount from the original q-axis current command of the inner current loop output by the outer voltage loop to get the new q-axis current command value.

[0108] Step S5: Determine the transfer function after adding capacitor current compensation to the outer voltage loop based on the compensation amount of the q-axis current command.

[0109] Based on the compensated q-axis current command, the transfer function of the outer voltage loop is recalculated. The compensated transfer function takes into account the influence of capacitor current and can more accurately describe the dynamic behavior of the system.

[0110] Step S6: Based on the transfer function after adding capacitor current compensation to the voltage outer loop, adjust the initial controller parameters of the voltage outer loop to obtain the final controller parameters of the voltage outer loop, and perform voltage regulation control on the motor using the final controller parameters of the voltage outer loop.

[0111] Based on the voltage outer loop compensation transfer function obtained in step S5, adjust the initial controller parameter K. p and K i This ensures that the system's response during actual operation meets design requirements. This step guarantees that the compensated controller can effectively control the DC bus voltage, preventing overshoot or instability in the system.

[0112] In one specific embodiment, the open-loop transfer function after adding capacitor current compensation to the outer voltage loop is:

[0113]

[0114] Among them, G I Let S be the closed-loop transfer function of the inner current loop, S be the complex frequency variable, C be the DC bus capacitance, and T be the current inner loop closed-loop transfer function. s For the switching period, k p ω is the proportional coefficient of the voltage outer loop controller. c Where is the cutoff frequency of the inner current loop, and K is the compensation coefficient.

[0115] like Figure 7 As shown, by analyzing the system's transfer function, it can be seen that the capacitor current compensation has already accelerated the system's dynamic response and increased the system's gain margin. Therefore, appropriately increasing the voltage outer loop gain can further accelerate the system's dynamic response and enhance the system's control effect.

[0116] By adjusting the final controller parameters, the voltage outer loop can stabilize the DC bus voltage under operating conditions, ensuring the stability and efficiency of motor operation.

[0117] In a specific example, co-simulation is performed using MAXWELL and SIMPLER, and the simulation setup is as follows: Figure 8As shown, the parameters of the dual three-phase permanent magnet synchronous motor used in the simulation are as follows: number of pole pairs: 2, permanent magnet flux linkage: 0.0693Wb, rated power: 250KW, rated speed: 18500r / min, stator resistance: 0.014ohm, d-axis inductance: 76.32uH, q-axis inductance: 84.88uH, bus capacitance consists of two parallel 1600uF capacitors, totaling 3200uF, and the target voltage is 540V. The simulation lasts for 50ms, with the load conditions as follows: 20% load from 0 to 10ms, 160% load from 10 to 30ms, and 20% load from 30 to 50ms.

[0118] Using the dual dq decoupling method, the control of the two three-phase motors is transformed into the control of two parallel three-phase motors. The simulation setup is as follows: Figure 8 As shown in the figure. In the simulation, the q-axis current of both windings is given by the outer voltage loop, the d-axis current is given as 0, and the dq-axis currents of both windings are given the same value. The switching frequency is set to 25000Hz.

[0119] Design the controller parameters for the inner current loop and outer voltage loop. Select the current loop bandwidth as 1 / 10 of the switching frequency, and obtain the current loop controller parameters and the current loop closed-loop transfer function using the bandwidth method. When calculating the voltage loop controller parameters, the current loop is equivalent to its simplified closed-loop transfer function. The voltage loop bandwidth is selected based on the actual voltage requirements and fine-tuned according to simulation results. Run the simulation and observe the current command waveform output by the outer voltage loop when the load changes abruptly, obtaining the time T for the current command to reach the required command.

[0120] Design the capacitor current calculation section and select an appropriate delay time T. delay The selected delay time cannot be greater than the time T obtained in step two; otherwise, the goal of accelerating the dynamic response cannot be achieved. This patent selects T. delay The calculated capacitor current waveform is as follows (for 3 switching cycles). Figure 9 As shown.

[0121] Derive the system transfer function and the transfer function of the load disturbance signal (load current) for different K values. Plot the Bode plot of the system transfer function and the step response of the load disturbance for different K values ​​in MATLAB, and determine the appropriate K value.

[0122] At this point, readjust the voltage loop controller parameters designed in step two. The voltage loop gain can be increased by 1.5 to 2 times. Redraw the Bode plot of the system using MATLAB to verify whether the system is stable at this point. Under the premise of ensuring sufficient phase margin, select a larger voltage loop gain factor.

[0123] Run the simulation and observe the q-axis current command waveform and DC bus voltage waveform before and after adding capacitor current compensation. The current command waveform is as follows: Figure 10As shown, the voltage waveform is as follows Figure 11 As shown. By Figure 10 With the addition of capacitor current compensation, the DC current flows more rapidly. Figure 11 Without capacitor current compensation, the voltage drops by 86.85V when a load is suddenly applied and rises by 109.94V when the load is suddenly removed. After capacitor current compensation, the voltage drops by 61.87V when a load is suddenly applied and rises by 80.22V when the load is suddenly removed. Moreover, the voltage recovery speed after capacitor current compensation is faster than before compensation.

[0124] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A voltage regulation control method for a dual three-phase permanent magnet synchronous motor based on capacitor current compensation, characterized in that, Includes the following steps: S1 decouples the two sets of three-phase windings of the dual three-phase permanent magnet synchronous motor to obtain the mathematical model of the dual three-phase motor. S2 determines the initial controller parameters for the voltage outer loop and current inner loop based on a mathematical model, and sets the compensation coefficient. The value of the compensation coefficient K is determined according to the transfer function of the load disturbance signal, which is: ； Among them, G I Let i be the closed-loop transfer function of the inner current loop. L U is the load current, U is the bus voltage, S is the complex frequency variable, C is the DC bus capacitance, and T is the load current. s For the switching period, k i k p These are the integral coefficient and proportional coefficient of the voltage outer loop controller, respectively; S3 collects the voltage of the DC bus in real time and calculates the capacitance current value of the DC bus. S4 obtains the compensation amount of the q-axis current command based on the compensation coefficient and the capacitor current value of the DC bus voltage. S5 determines the transfer function of the voltage outer loop after adding capacitor current compensation based on the compensation amount of the q-axis current command. S6 adjusts the initial controller parameters of the voltage outer loop based on the transfer function after capacitor current compensation, to obtain the final controller parameters of the voltage outer loop. The motor is then regulated using these final controller parameters. The open-loop transfer function after capacitor current compensation is as follows: ； Among them, G I Let S be the closed-loop transfer function of the inner current loop, S be the complex frequency variable, C be the DC bus capacitance, and T be the current inner loop closed-loop transfer function. s For the switching period, k p ω is the proportional coefficient of the voltage outer loop controller. c Where is the cutoff frequency of the inner current loop, and K is the compensation coefficient.

2. The voltage regulation control method for a dual three-phase permanent magnet synchronous motor based on capacitor current compensation as described in claim 1, characterized in that, In step S1, the mathematical model includes voltage equations, flux linkage equations, and torque equations, which are as follows: ； Among them, u d1 u d2 u q1 u q2 These are the dq-axis voltages of the two windings, i d1 i d2 i q1 i q2 These are the dq-axis currents of the two sets of windings, respectively. The dq axis flux linkages are two sets of windings, ω e The electric angular velocity of the motor. For permanent magnet flux linkage, L d L q For the dq axis inductance, L dd L qq For the d-axis mutual inductance and q-axis mutual inductance between the two sets of windings, T e denoted as the electromagnetic torque of the motor, p as the number of pole pairs of the motor, and R as the stator resistance of the motor.

3. The voltage regulation control method for a dual three-phase permanent magnet synchronous motor based on capacitor current compensation as described in claim 1, characterized in that, Step S1 includes the following steps: S11 transforms the current of the two sets of three-phase windings of the dual three-phase permanent magnet synchronous motor into two independent dq coordinate systems; S12 expresses the voltage equations of the two windings of the motor as independent dq-axis voltage equations in the dq coordinate system; S13 associates the flux linkage equations of the two windings with the corresponding dq axis currents and inductance matrices, respectively, to decouple the flux linkages and obtain the mathematical model of the dual three-phase motor.

4. The voltage regulation control method for a dual three-phase permanent magnet synchronous motor based on capacitor current compensation as described in claim 2, characterized in that, Step S2 includes the following steps: S21 determines the controller parameters for the inner current loop based on the mathematical model; S22 obtains the closed-loop transfer function of the current inner loop through the controller parameters of the current inner loop; S23 obtains the initial controller parameters of the voltage outer loop based on the closed-loop transfer function of the inner current loop.

5. The voltage regulation control method for a dual three-phase permanent magnet synchronous motor based on capacitor current compensation as described in claim 4, characterized in that, In step S21, the bandwidth of the outer current loop is set to 1 / 10 of the switching frequency, and the controller parameters of the inner current loop are: ； Where, k id k pd These are the integral and proportional coefficients of the d-axis current controller, respectively, k iq k pq These are the integral and proportional coefficients of the q-axis current controller, respectively; R is the stator resistance of the motor; and T is the linear coefficient. s For the switching period, ω c This is the cutoff frequency of the inner current loop.

6. The voltage regulation control method for a dual three-phase permanent magnet synchronous motor based on capacitor current compensation as described in claim 5, characterized in that, In step S22, the transfer function of the inner current loop and its simplified result are as follows: ； Where, k idq S represents the integral coefficients of the d-axis and q-axis controllers of the current inner loop, and S is the complex frequency variable.

7. The voltage regulation control method for a dual three-phase permanent magnet synchronous motor based on capacitor current compensation as described in claim 6, characterized in that, In step S23, the initial controller parameters for the outer voltage loop are: ； Where, k i k p These are the integral and proportional coefficients of the voltage outer loop controller, ω. cu R is the voltage outer loop cutoff frequency, T is the current inner loop equivalent time constant, and R is the voltage outer loop cutoff frequency. L C is the load resistance, and C is the DC bus capacitance.

8. The voltage regulation control method for a dual three-phase permanent magnet synchronous motor based on capacitor current compensation as described in claim 1, characterized in that, In step S3, the capacitance current value of the DC bus is expressed as: ； Among them, I c T is the capacitor current value. delay The delay time between the two voltage acquisitions is ΔU, the difference between the two DC bus voltage acquisitions is ΔU, and C is the DC bus capacitance.

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