A predictive control method for electromagnetic noise of silicon carbide controller for automobile

Abstract

The present invention provides a method for predicting and controlling electromagnetic noise of a silicon carbide controller for a vehicle, comprising receiving parameters such as d-axis current, q-axis current, rated torque and actual speed to calculate a speed error signal; using a discrete anti-integral saturation speed PI controller to calculate a reference torque according to the error signal, and further deriving the modulation wave frequency, electrical angular frequency and stator flux. Through a current prediction control algorithm, the d-axis and q-axis voltages at the next moment are predicted and compensated to obtain the predicted values ​​of torque and electromagnetic noise, and the carrier ratio predicted value at the next moment is calculated. The cost function under different switching states is calculated, and the function comprehensively considers the weight factors of the carrier ratio and the common mode voltage EMI suppression value. The value that minimizes the cost function is selected for digital filtering and output to the silicon carbide controller, thereby driving the permanent magnet synchronous motor to operate. It is intended to effectively reduce the electromagnetic interference generated in high-frequency switching operations and improve the output performance of the motor.

Description

Technical Field

[0001] The present invention relates to the field of electromagnetic interference technology, and in particular to a method for predicting and controlling electromagnetic noise of a silicon carbide controller for a vehicle. Background Art

[0002] As the world pays more attention to environmental protection and sustainable development, electric vehicles (EVs), as a clean energy means of transportation, are gradually becoming an important direction for the development of the automotive industry. At present, the core of electric vehicles lies in their electric drive systems, which provide power for the vehicle through efficient electric energy conversion, and the performance of the electric drive system directly affects the driving efficiency and reliability of electric vehicles.

[0003] In the electric drive system of electric vehicles, the motor controller plays a vital role. It is responsible for accurately controlling the speed and torque of the motor to ensure the power output and driving performance of the electric vehicle. However, with the increase in the operating frequency of the motor controller, especially in the controller using silicon carbide (SiC) devices, the problem of electromagnetic interference (EMI) generated by high-frequency switching operations has become particularly prominent. Specifically, electromagnetic interference will not only reduce the performance of electronic equipment inside electric vehicles, but may also cause electromagnetic pollution to the surrounding environment, affect the normal operation of other electronic equipment, and even interfere with radio communication facilities. Therefore, electromagnetic compatibility (EMC) has become a key factor that must be considered in the design of electric vehicles.

[0004] In the current market, silicon carbide controllers are widely used in electric drive systems of electric vehicles due to their excellent high-temperature performance, high efficiency and high-frequency characteristics. However, the EMI problem generated by silicon carbide devices during high-frequency switching not only poses a challenge to the stability and reliability of the entire vehicle system, but also causes electromagnetic pollution to the surrounding environment. Traditional EMI suppression methods often have limited effects and may affect the performance of the motor controller.

[0005] In view of this, this application is filed. Summary of the invention

[0006] The present invention provides a method for predicting and controlling electromagnetic noise of a silicon carbide controller for a vehicle, which can at least partially improve the above-mentioned problem.

[0007] To achieve the above object, the present invention adopts the following technical solutions:

[0008] A method for predicting and controlling electromagnetic noise of a silicon carbide controller for a vehicle, comprising:

[0009] Acquire a reference speed, a rated torque, and an actual output speed of the electric vehicle to be controlled, and obtain a speed error signal according to the reference speed and the actual output speed of the motor, and update the speed error signal and the rated torque to update and calculate a reference torque of a PI controller of the electric vehicle to be controlled;

[0010] Performing calculation preprocessing on the actual output speed of the motor to obtain the modulation wave frequency, electrical angle frequency and stator flux linkage of the electric vehicle to be controlled;

[0011] Obtaining the d-axis current and q-axis current of the electric vehicle to be controlled, calculating the voltage of the permanent magnet synchronous motor of the electric vehicle to be controlled according to the d-axis current, the q-axis current and the electrical angular frequency, discretizing the voltage of the permanent magnet synchronous motor based on the electrical angular frequency, and performing current prediction control calculation to obtain an estimated value of the d-axis voltage at time k+1 and an estimated value of the q-axis voltage at time k+1;

[0012] Based on the d-axis current, the q-axis current, the estimated value of the d-axis voltage at time k+1, and the estimated value of the q-axis voltage at time k+1, compensation processing, coordinate conversion processing, and calculation processing are performed to obtain the torque prediction value and the EMI prediction value at time k+1;

[0013] Acquire the initial switching frequency of the electric vehicle to be controlled, and calculate the carrier ratio prediction value at the next moment according to the initial switching frequency and the modulation wave frequency;

[0014] Repeat the above steps to calculate the cost function corresponding to each switching state of the space vector pulse width modulation SVPWM of the electric vehicle to be controlled, screen out the switching state corresponding to the minimum cost function value, and perform digital filtering on the d-axis voltage and q-axis voltage corresponding to this switching state, and input the filtered d-axis voltage and q-axis voltage into the silicon carbide controller of the electric vehicle to be controlled to drive the permanent magnet synchronous motor of the electric vehicle to be controlled.

[0015] In summary, the electromagnetic noise predictive control method of the automotive silicon carbide controller aims to significantly reduce the electromagnetic interference caused by the high-frequency switching operation of the silicon carbide device, while optimizing the output characteristics of the motor; through a carefully designed predictive control algorithm, the method can monitor and adjust the operating status of the motor in real time to ensure that the electromagnetic noise is effectively suppressed, thereby improving the stability and reliability of the electric drive system of the electric vehicle.

[0016] Specifically, the core steps of the method include: inputting key motor operating parameters, such as initial switching frequency, d-axis and q-axis currents, rated torque and reference speed; using a PI controller to process the speed error signal and calculate the reference torque; calculating the modulation wave frequency, electrical angular frequency and stator flux; applying a zero-beat predictive control algorithm to predict the d-axis and q-axis voltages at the next moment; obtaining the predicted values ​​of torque and electromagnetic noise through delay compensation; and finally, selecting the optimal control strategy by minimizing the cost function, which comprehensively considers the weight factors of the carrier ratio and the EMI suppression value.

[0017] Compared with the existing technology, the uniqueness of this method lies in the use of discrete anti-integral saturation speed PI controller and the optimization of EMI suppression effect by adjusting the EMI weight factor in the cost function. It can not only monitor and reduce the EMI of the silicon carbide controller in real time, but also achieve stable operation and good output characteristics of the motor, effectively reducing the electromagnetic interference of the inverter induction motor system. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the overall process of the electromagnetic noise prediction control method of the automotive silicon carbide controller provided by an embodiment of the present invention;

[0019] Figure 2 It is a flow chart of an electromagnetic noise prediction and control method of a silicon carbide controller for a vehicle provided by an embodiment of the present invention;

[0020] Figure 3 The PI controller provided by the embodiment of the present invention is a design diagram of a discrete anti-integral saturation speed controller;

[0021] Figure 4 3. It is a schematic diagram of THD analysis of conventional current prediction at a switching frequency of 30kHz provided by an embodiment of the present invention;

[0022] Figure 5 3. It is a schematic diagram of PSD analysis of conventional current prediction at a switching frequency of 30kHz provided by an embodiment of the present invention;

[0023] Figure 6 3 is a schematic diagram of THD analysis of an electromagnetic noise prediction control method of a silicon carbide controller for a vehicle at a switching frequency of 30 kHz provided by an embodiment of the present invention;

[0024] Figure 7 It is a PSD analysis diagram of the electromagnetic noise prediction control method of the automotive silicon carbide controller at a switching frequency of 30kHz provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0026] refer to Figure 1 , Figure 2 As shown, the first embodiment of the present invention discloses a method for predicting and controlling electromagnetic noise of a silicon carbide controller for a vehicle, which can be executed by a device for predicting and controlling electromagnetic noise of a silicon carbide controller for a vehicle (hereinafter referred to as a control device), and in particular, by one or more processors in the control device to implement the following method:

[0027] S1, obtaining a reference speed, a rated torque, and an actual output speed of the electric vehicle to be controlled, and obtaining a speed error signal according to the reference speed and the actual output speed of the motor, and updating the speed error signal and the rated torque to update and calculate a reference torque of a PI controller of the electric vehicle to be controlled;

[0028] Specifically, step S1 includes: obtaining a reference speed of the electric vehicle to be controlled , Rated torque , and the actual output speed of the motor of the electric vehicle detected by the preset detector ;

[0029] According to the reference speed And the actual output speed of the motor The speed error signal e is calculated using the following formula: ;

[0030] According to the formula Calculate the reference torque of the PI controller of the electric vehicle to be controlled ,in, , is the proportional gain, is the integral gain, is the sampling period of the PI controller, is the discretization level in the z plane, The initial value is .

[0031] See also Figure 3 Preferably, the PI controller of the electric vehicle to be controlled adopts a discrete anti-integral saturation speed controller.

[0032] In this embodiment, the initial switching frequency, d-axis current, q-axis current, rated torque and reference speed are first input; the actual output speed is compared with the reference speed to obtain a speed error signal, and the PI controller receives the speed error signal to calculate the reference torque.

[0033] S2, performing calculation preprocessing on the actual output speed of the motor to obtain the modulation wave frequency, electrical angle frequency and stator flux of the electric vehicle to be controlled;

[0034] Specifically, step S2 includes: according to the formula Calculate the modulation wave frequency of the electric vehicle to be controlled ,in, is the pole pair number;

[0035] According to the modulation wave frequency Calculate the electrical angular frequency of the electric vehicle to be controlled , the calculation formula is: ;

[0036] The electrical angular frequency Substitute into the formula Calculate the stator flux ,in, is the no-load reverse electromotive force.

[0037] In this embodiment, the corresponding modulation wave frequency, electrical angular frequency and stator flux are calculated according to the parameter values ​​calculated in the previous step.

[0038] S3, obtaining the d-axis current and q-axis current of the electric vehicle to be controlled, calculating the voltage of the permanent magnet synchronous motor of the electric vehicle to be controlled according to the d-axis current, the q-axis current and the electrical angular frequency, discretizing the voltage of the permanent magnet synchronous motor based on the electrical angular frequency, and performing current prediction control calculation to obtain an estimated value of the d-axis voltage at time k+1 and an estimated value of the q-axis voltage at time k+1;

[0039] Specifically, step S3 includes: obtaining the d-axis current of the electric vehicle to be controlled and q-axis current ;

[0040] Based on d-axis current , q-axis current , electrical angular frequency And voltage formula Calculate the voltage of the permanent magnet synchronous motor of the electric vehicle to be controlled, where: is the d-axis voltage, is the q-axis voltage, is the stator resistance, is the d-axis inductance, is the q-axis inductance, is the time derivative of the d-axis current, is the time derivative of the q-axis current;

[0041] The voltage of the permanent magnet synchronous motor is discretized to obtain a discretized voltage formula: ,in, is the d-axis voltage at time k, is the q-axis voltage at time k, is the d-axis current at time k, is the q-axis current at time k, is the time derivative of inductance, is the d-axis current at the time k+1 after discretization, is the q-axis current at the time k+1 after discretization;

[0042] Based on the voltage formula and the discretized voltage formula, current prediction control calculation is performed to obtain the estimated value of the d-axis voltage at time k+1 , and the estimated value of the q-axis voltage at time k+1 , the calculation formula is: ,in, is the given value of d-axis current, is the given value of q-axis current.

[0043] In this embodiment, estimated values ​​of the d-axis voltage and the q-axis voltage at time k+1 are calculated by current prediction control.

[0044] S4, performing compensation processing, coordinate conversion processing, and calculation processing based on the d-axis current, the q-axis current, the estimated value of the d-axis voltage at time k+1, and the estimated value of the q-axis voltage at time k+1, to obtain a torque prediction value and an EMI prediction value at time k+1;

[0045] Specifically, step S4 includes: calculating the d-axis current at time k and the q-axis current at time k Perform delay compensation to obtain the d-axis current at time k+1 and the q-axis current at time k+1 , the formula is: ,in, is the d-axis voltage at time k-1, is the q-axis voltage at time k-1;

[0046] According to the d-axis current at time k+1 and the q-axis current at time k+1 Calculate the predicted value of the d-axis voltage at time k+1 , and the predicted value of the q-axis voltage at time k+1 , the formula is: ;

[0047] Based on the stator flux , d-axis current at time k+1 and the q-axis current at time k+1 Calculate the torque prediction value at time k+1 ;

[0048] The predicted value of the d-axis voltage at the k+1 moment And the predicted value of the q-axis voltage at time k+1 Perform coordinate transformation to obtain the three-phase voltage value , , ;

[0049] According to the three-phase voltage value , , Calculating EMI predictions , the calculation formula is: .

[0050] S5, obtaining the initial switching frequency of the electric vehicle to be controlled, and calculating the carrier ratio prediction value at the next moment according to the initial switching frequency and the modulation wave frequency;

[0051] Preferably, the carrier ratio prediction value The calculation formula is: ,in, is the initial switching frequency.

[0052] In this embodiment, the torque prediction value is obtained by delay compensation, and the predicted carrier ratio and EMI prediction value are calculated.

[0053] S6, repeat the above steps, calculate the cost function corresponding to each switching state of the space vector pulse width modulation SVPWM of the electric vehicle to be controlled, filter out the switching state corresponding to the minimum cost function value, and perform digital filtering on the d-axis voltage and q-axis voltage corresponding to this switching state, and input the filtered d-axis voltage and q-axis voltage into the silicon carbide controller of the electric vehicle to be controlled to drive the permanent magnet synchronous motor of the electric vehicle to be controlled to operate.

[0054] Preferably, the formula of the cost function g is: ,in, is the weight factor of the carrier ratio in the cost function, , is the weight factor of the common mode voltage EMI suppression value in the cost function.

[0055] Preferably, before calculating the cost function corresponding to each switching state of the space vector pulse width modulation SVPWM of the electric vehicle to be controlled, the method further includes:

[0056] Let the weight factor of the common mode voltage EMI suppression value be is 0, and the weight factor of the common mode voltage EMI suppression value is gradually increased according to the preset growth value ;

[0057] Record the weight factor of each common mode voltage EMI suppression value The corresponding output speed, carrier ratio and EMI measurement value;

[0058] Filter out the weight factor of the common mode voltage EMI suppression value corresponding to the minimum EMI measurement value , as the final value.

[0059] Preferably, the first order of magnitude of the preset growth value is {0, 0.001, 0.01, 0.1, ..., R}, and the second order of magnitude of the preset growth value is half of the first order of magnitude, wherein R is a natural number.

[0060] Specifically, in this embodiment, the cost function in each switch state in the sampling period is finally calculated as above, and the data corresponding to the minimum value of the cost function is used as the output value to complete the EMI suppression control.

[0061] In this embodiment, , it means that the motor torque and the carrier ratio are given the same weight.

[0062] Furthermore, by changing the weight factor of EMI in the cost function To adjust the impact of EMI on the motor output torque and carrier ratio, adjust The method is: at the beginning ,Then The value increases continuously, and each The output speed, carrier ratio and EMI measurement value corresponding to the value are selected to minimize EMI while ensuring good motor output characteristics. At the beginning, it is prioritized to determine the order of magnitude, and the values ​​are set to 0, 0.001, 0.01, 0.1, 1…, and then the optimal order of magnitude is selected, and the values ​​are continued to be determined in units of half the new interval (0.005, 0.05, 0.5…) until the required value is obtained.

[0063] In this embodiment, the space vector pulse width modulation SVPWM of the electric vehicle to be controlled includes 8 switches, so the values ​​that minimize the cost function under the 8 switch states are taken for digital filtering and output to the silicon carbide controller, which drives the permanent magnet synchronous motor to operate.

[0064] In summary, the automotive silicon carbide controller electromagnetic noise prediction control method achieves stable operation of the motor by calculating the output torque prediction value of the motor at the next sampling moment, as well as the carrier ratio prediction value, and then tracks the motor output torque reference value and the motor carrier ratio reference value, while outputting the switching state that minimizes EMI at the next moment. It can effectively reduce the electromagnetic interference of the inverter induction motor system, detect and reduce the EMI of each switching state of the silicon carbide controller in real time, and achieve good output characteristics.

[0065] The above is a preferred embodiment of the present invention. It should be pointed out that a person skilled in the art can make several improvements and modifications without departing from the principle of the present invention. These improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A method for predicting and controlling electromagnetic noise of a silicon carbide controller for a vehicle, characterized in that: include: Acquire a reference speed, a rated torque, and an actual output speed of the electric vehicle to be controlled, and obtain a speed error signal according to the reference speed and the actual output speed of the motor, and update the speed error signal and the rated torque to update and calculate a reference torque of a PI controller of the electric vehicle to be controlled; Performing calculation preprocessing on the actual output speed of the motor to obtain the modulation wave frequency, electrical angle frequency and stator flux linkage of the electric vehicle to be controlled; Obtaining the d-axis current and q-axis current of the electric vehicle to be controlled, calculating the voltage of the permanent magnet synchronous motor of the electric vehicle to be controlled according to the d-axis current, the q-axis current and the electrical angular frequency, discretizing the voltage of the permanent magnet synchronous motor based on the electrical angular frequency, and performing current prediction control calculation to obtain an estimated value of the d-axis voltage at time k+1 and an estimated value of the q-axis voltage at time k+1; Based on the d-axis current, the q-axis current, the estimated value of the d-axis voltage at time k+1, and the estimated value of the q-axis voltage at time k+1, compensation processing, coordinate conversion processing, and calculation processing are performed to obtain the torque prediction value and the EMI prediction value at time k+1; Acquire the initial switching frequency of the electric vehicle to be controlled, and calculate the carrier ratio prediction value at the next moment according to the initial switching frequency and the modulation wave frequency; Repeat the above steps to calculate the cost function corresponding to each switching state of the space vector pulse width modulation SVPWM of the electric vehicle to be controlled, select the switching state corresponding to the minimum cost function value, and perform digital filtering on the d-axis voltage and q-axis voltage corresponding to the switching state, and input the filtered d-axis voltage and q-axis voltage into the silicon carbide controller of the electric vehicle to be controlled to drive the permanent magnet synchronous motor of the electric vehicle to be controlled to operate; The reference speed, rated torque, and actual output speed of the electric vehicle to be controlled are obtained, and a speed error signal is obtained according to the reference speed and the actual output speed of the motor. The speed error signal and the rated torque are updated to update and calculate the reference torque of the PI controller of the electric vehicle to be controlled, specifically: Get the reference speed of the electric vehicle to be controlled , Rated torque , and the actual output speed of the motor of the electric vehicle detected by the preset detector ; According to the reference speed And the actual output speed of the motor The speed error signal e is calculated using the following formula: ; According to the formula Calculate the reference torque of the PI controller of the electric vehicle to be controlled ,in, , is the proportional gain, is the integral gain, is the sampling period of the PI controller, is the discretization level in the z plane, The initial value is .

2. The method for predicting and controlling electromagnetic noise of a silicon carbide controller for a vehicle according to claim 1, characterized in that: The PI controller of the electric vehicle to be controlled adopts a discrete anti-integral saturation speed controller.

3. The method for predicting and controlling electromagnetic noise of a silicon carbide controller for a vehicle according to claim 1, characterized in that: The actual output speed of the motor is calculated and preprocessed to obtain the modulation wave frequency, electrical angle frequency and stator flux of the electric vehicle to be controlled, specifically: According to the formula Calculate the modulation wave frequency of the electric vehicle to be controlled ,in, is the pole pair number; According to the modulation wave frequency Calculate the electrical angular frequency of the electric vehicle to be controlled , the calculation formula is: ; The electrical angular frequency Substitute into the formula Calculate the stator flux ,in, is the no-load reverse electromotive force.

4. The method for predicting and controlling electromagnetic noise of a silicon carbide controller for a vehicle according to claim 3, characterized in that: The d-axis current and q-axis current of the electric vehicle to be controlled are obtained, and the voltage of the permanent magnet synchronous motor of the electric vehicle to be controlled is calculated according to the d-axis current, the q-axis current and the electrical angular frequency. The voltage of the permanent magnet synchronous motor is discretized and the current prediction control calculation is performed based on the electrical angular frequency to obtain an estimated value of the d-axis voltage at time k+1 and an estimated value of the q-axis voltage at time k+1, specifically: Get the d-axis current of the electric vehicle to be controlled and q-axis current ; Based on d-axis current , q-axis current , electrical angular frequency And voltage formula Calculate the voltage of the permanent magnet synchronous motor of the electric vehicle to be controlled, where: is the d-axis voltage, is the q-axis voltage, is the stator resistance, is the d-axis inductance, is the q-axis inductance, is the time derivative of the d-axis current, is the time derivative of the q-axis current; The voltage of the permanent magnet synchronous motor is discretized to obtain a discretized voltage formula: ,in, is the d-axis voltage at time k, is the q-axis voltage at time k, is the d-axis current at time k, is the q-axis current at time k, is the time derivative of inductance, is the d-axis current at the time k+1 after discretization, is the q-axis current at the time k+1 after discretization; Based on the voltage formula and the discretized voltage formula, current prediction control calculation is performed to obtain the estimated value of the d-axis voltage at time k+1 , and the estimated value of the q-axis voltage at time k+1 , the calculation formula is: ,in, is the given value of d-axis current, is the given value of q-axis current.

5. The method for predicting and controlling electromagnetic noise of a silicon carbide controller for a vehicle according to claim 4, characterized in that: Based on the d-axis current, the q-axis current, the estimated value of the d-axis voltage at time k+1, and the estimated value of the q-axis voltage at time k+1, compensation processing, coordinate conversion processing, and calculation processing are performed to obtain the torque prediction value and EMI prediction value at time k+1, which are specifically: For the d-axis current at time k and the q-axis current at time k Perform delay compensation to obtain the d-axis current at time k+1 and the q-axis current at time k+1 , the formula is: ,in, is the d-axis voltage at time k-1, is the q-axis voltage at time k-1; According to the d-axis current at time k+1 and the q-axis current at time k+1 Calculate the predicted value of the d-axis voltage at time k+1 , and the predicted value of the q-axis voltage at time k+1 , the formula is: ; Based on the stator flux , d-axis current at time k+1 and the q-axis current at time k+1 Calculate the torque prediction value at time k+1 ; The predicted value of the d-axis voltage at the k+1 moment And the predicted value of the q-axis voltage at time k+1 Perform coordinate transformation to obtain the three-phase voltage value , , ; According to the three-phase voltage value , , Calculating EMI predictions , the calculation formula is: .

6. The method for predicting and controlling electromagnetic noise of a silicon carbide controller for a vehicle according to claim 5, characterized in that: The carrier ratio prediction value The calculation formula is: ,in, is the initial switching frequency.

7. The method for predicting and controlling electromagnetic noise of a silicon carbide controller for a vehicle according to claim 6, characterized in that: The formula of the cost function g is: ,in, is the weight factor of the carrier ratio in the cost function, , is the weight factor of the common mode voltage EMI suppression value in the cost function.

8. The method for predicting and controlling electromagnetic noise of a silicon carbide controller for a vehicle according to claim 7, characterized in that: Before calculating the cost function corresponding to each switching state of the space vector pulse width modulation SVPWM of the electric vehicle to be controlled, it also includes: Let the weight factor of the common mode voltage EMI suppression value be =0, and gradually increase the weight factor of the common mode voltage EMI suppression value according to the preset growth value ; Record the weight factor of each common mode voltage EMI suppression value The corresponding output speed, carrier ratio and EMI measurement value; Filter out the weight factor of the common mode voltage EMI suppression value corresponding to the minimum EMI measurement value , as the final value.

9. The method for predicting and controlling electromagnetic noise of a silicon carbide controller for a vehicle according to claim 8, characterized in that: The first order of magnitude of the preset growth value is {0, 0.001, 0.01, 0.1, ..., R}, and the second order of magnitude of the preset growth value is half of the first order of magnitude, wherein R is a natural number.

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