Harmonic current suppression method and device, electronic equipment and storage medium

Abstract

The present application relates to the technical field of motor control, and discloses a harmonic current suppression method and device, electronic equipment and a storage medium. The harmonic current suppression method is applied to a low-speed light-load working condition of a motor, and includes: collecting sine envelope signals and cosine envelope signals of a rotary transformer, dynamically calibrating the amplitude and bias of the sine envelope signals and the cosine envelope signals for self-learning, so that the output current signal becomes a first current signal; performing dead zone compensation in a three-phase asymmetric dead zone compensation mode, so that the output current signal changes from the first current signal to a second current signal; and accumulating an adjustment voltage on a current loop output voltage, so that the output current signal changes from the second current signal to a final current signal, and the adjustment voltage is output by a proportional-resonant control algorithm with improved bandwidth enhancement. The present application can suppress the noise caused by harmonic current of low-speed light-load working condition and high-order current noise, and has a good current harmonic suppression effect.

Description

Technical Field

[0001] This invention relates to the field of motor control technology, and more specifically to harmonic current suppression methods, devices, electronic equipment, and storage media. Background Technology

[0002] With the rapid development of new energy vehicles, the application of motor control technology in areas such as main drive, power generation, steering, and braking is becoming increasingly mature. Among these, NVH (Noise, Vibration, and Harshness) is a major focus of the new energy vehicle industry. Under low-speed, light-load conditions, the motor exhibits low voltage utilization, small phase voltage vector amplitude, and significant dead-zone voltage drop, tube voltage drop, and line voltage drop. Furthermore, when the fundamental current is relatively low, harmonic currents also exhibit high coupling, high proportion, asymmetry, and complex order.

[0003] There are many traditional methods for suppressing harmonic currents, generally targeting the source of the harmonic current and its vibration and noise. Examples include: cogging torque compensation schemes, which compensate for the motor's cogging torque; and open-loop voltage injection schemes, which compensate for specific harmonic orders, such as the 5th and 7th, 11th and 13th harmonics. However, cogging torque compensation schemes have coarse current harmonic suppression effects, and open-loop voltage injection schemes suffer from large compensation deviations under low-speed, light-load conditions. Summary of the Invention

[0004] This invention provides a method, apparatus, electronic device, and storage medium for suppressing harmonic currents, in order to solve the problem that traditional methods for suppressing harmonic currents are ineffective in suppressing current harmonics under low-speed and light-load conditions of motors.

[0005] In a first aspect, the present invention provides a harmonic current suppression method, applied to low-speed, light-load conditions of motors, comprising: The sinusoidal and cosine envelope signals of the rotary transformer are acquired, and the amplitude and bias of the sinusoidal and cosine envelope signals are dynamically calibrated through self-learning so that the output current signal becomes the first current signal. Dead zone compensation is performed by using a three-phase asymmetrical dead zone compensation method, so that the output current signal changes from the first current signal to the second current signal; An adjustment voltage is accumulated on the output voltage of the current loop, so that the output current signal changes from the second current signal to the final current signal. The adjustment voltage is output by an improved proportional resonant control algorithm, which is an improved algorithm with enhanced bandwidth.

[0006] In one optional implementation, the sinusoidal and cosine envelope signals of the rotary transformer are acquired, and the amplitude and bias of the sinusoidal and cosine envelope signals are dynamically calibrated through self-learning, including: After power-on, once the amplitude and frequency of the excitation signal output by the controller to the rotary transformer are fixed, two arrays with preset index lengths are used as moving sampling windows to collect the amplitude and bias of the sine envelope signal and the cosine envelope signal, respectively. The amplitudes of the sine and cosine envelope signals are extracted using a dynamic averaging method to obtain dynamically calculated amplitude values. The bias of the sine and cosine envelope signals is obtained by subtracting the peaks and troughs and then averaging the results, thus obtaining the dynamically calculated bias value. Dynamic averaging is performed on the dynamically obtained amplitude values ​​and the dynamically obtained bias values ​​to obtain the dynamic calibration values ​​for amplitude and bias. Before the controller initialization is complete, save the amplitude dynamic calibration value and the bias dynamic calibration value to the chip's memory; Upon power-on again, the stored amplitude dynamic calibration value and bias dynamic calibration value are read from the memory and compared with the dynamically obtained values ​​during the power-on initialization process to perform self-learning dynamic calibration.

[0007] In one optional implementation, during dead zone compensation, the compensation value and compensation rate for each phase of the three-phase asymmetry dead zone are dynamically calibrated online until the degree of three-phase asymmetry is reduced.

[0008] In one optional implementation, the inputs to the proportional resonance control algorithm include direct-axis current error, quadrature-axis current error, and a proportional resonance term. The outputs of the proportional resonance control algorithm include direct-axis adjustment voltage and quadrature-axis adjustment voltage. The proportional resonance term is determined based on the electric angular velocity calculated after self-learning dynamic calibration and compensation.

[0009] In one alternative implementation, the closed-loop transfer function of the proportional resonant control algorithm is based on the resonant bandpass filter transfer function with the addition of a damping coefficient, a resonant gain coefficient, and a proportional coefficient.

[0010] In one alternative implementation, the closed-loop transfer function is discretized into several mathematical branches by first reducing its order and then merging like terms. Each mathematical branch is discretized to differential, integral, or constant form.

[0011] In one alternative implementation, the direct-axis regulating voltage and the quadrature-axis regulating voltage are low-pass filtered voltages.

[0012] Secondly, the present invention provides a harmonic current suppression device, the device comprising: The preprocessing module is used to acquire the sinusoidal and cosine envelope signals of the rotary transformer, and to perform self-learning dynamic calibration on the amplitude and bias of the sinusoidal and cosine envelope signals so that the output current signal becomes the first current signal. The modulation processing module is used to perform dead zone compensation by means of three-phase asymmetric dead zone compensation, so that the output current signal is changed from the first current signal to the second current signal. The input processing module is used to accumulate and adjust the voltage on the current loop output voltage, so that the output current signal changes from the second current signal to the final current signal. The adjusted voltage is output by an improved proportional resonant control algorithm, which is an improved algorithm with enhanced bandwidth.

[0013] Thirdly, the present invention provides an electronic device, comprising: a memory and a processor, wherein the memory and the processor are communicatively connected to each other, the memory stores computer instructions, and the processor executes the computer instructions to perform the harmonic current suppression method of the first aspect or any corresponding embodiment described above.

[0014] Fourthly, the present invention provides a computer-readable storage medium storing computer instructions for causing a computer to perform the harmonic current suppression method of the first aspect or any corresponding embodiment thereof.

[0015] The technical solution provided by this invention has at least the following beneficial effects: By acquiring the sinusoidal and cosine envelope signals of the rotary transformer and performing self-learning dynamic calibration on the amplitude and bias of these signals, the second harmonic current under low speed and light load conditions can be almost completely eliminated, meaning the second harmonic current is essentially eliminated from the first current signal. Furthermore, by employing three-phase asymmetrical dead-time compensation, the third harmonic current under low speed and light load conditions can be somewhat suppressed, and the amplitudes of the 11th and 13th harmonic currents are significantly reduced, meaning the second current signal not only essentially eliminates the second harmonic current but also... The method effectively suppresses not only the second harmonic current, but also the third, eleventh, and thirteenth harmonic currents. An regulated voltage is accumulated on the current loop output voltage, output by an improved proportional-resonant control algorithm. This algorithm, with enhanced bandwidth, achieves closed-loop harmonic suppression, effectively reducing the amplitudes of the remaining third, fifth, seventh, eleventh, and thirteenth harmonic currents to very low levels. In other words, noise caused by order harmonic currents and higher-order current noise in the final current signal is suppressed. The harmonic current suppression method provided by this invention has excellent current harmonic suppression performance. Attached Figure Description

[0016] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0017] Figure 1 This is a schematic flowchart of a harmonic current suppression method according to an embodiment of the present invention; Figure 2 This is a schematic diagram of a harmonic current suppression method according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the self-learning dynamic calibration process according to an embodiment of the present invention; Figure 4 This is a schematic diagram of an improved proportional resonance control algorithm according to an embodiment of the present invention; Figure 5 This is a schematic diagram of the discretization of the closed-loop transfer function according to an embodiment of the present invention. Figure 6 This is a waveform diagram of the three-phase current of a motor without any harmonic suppression measures according to an embodiment of the present invention; Figure 7 This is a diagram showing the FFT waveform of the three-phase motor current after self-learning dynamic calibration according to an embodiment of the present invention. Figure 8 This is a diagram showing the FFT waveform of the three-phase current of the motor after asymmetric dead zone compensation according to an embodiment of the present invention. Figure 9 This is a diagram showing the FFT waveform of the three-phase current of the motor after enabling the proportional resonance control algorithm according to an embodiment of the present invention. Figure 10 This is a comparison diagram of the phase current before and after the implementation of the harmonic current suppression method according to an embodiment of the present invention; Figure 11 This is a comparison diagram of the three-phase current order noise before and after the implementation of the harmonic current suppression method according to an embodiment of the present invention. Figure 12 This is a comparison diagram of the noise effect of torque in the tangential, radial and axial directions before and after the execution of the harmonic current suppression method according to an embodiment of the present invention; Figure 13 This is a structural block diagram of a harmonic current suppression device according to an embodiment of the present invention; Figure 14 This is a schematic diagram of the hardware structure of an electronic device according to an embodiment of the present invention. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] It is understood that before using the technical solutions disclosed in the various embodiments of the present invention, users should be informed of the types, scope of use, and usage scenarios of the personal information involved in the present invention and their authorization should be obtained in accordance with relevant laws and regulations through appropriate means.

[0020] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0021] In related technologies, schemes for compensating for motor cogging torque employ torque compensation in the low-speed range near 0 motor speed. This involves calibrating the negative sequence compensation angle and torque, and then applying the torque compensation, obtained by multiplying the calibrated torque by the sine of the negative sequence angle, to the actual output torque. However, this cogging torque compensation scheme relies on the stable speed and load of the dynamometer test bench, which cannot simulate the complex operating conditions of a vehicle on a real-world road. Furthermore, calibration under vehicle conditions is entirely based on vibration and noise data, making dynamic calibration heavily dependent on sensory perception. This makes it difficult to effectively observe the order data of harmonic currents, resulting in coarse-grained current harmonic suppression.

[0022] While the open-loop voltage injection scheme is relatively simple to calibrate and implement, it involves a significant workload. Furthermore, under low-speed, light-load conditions, the amplitude and phase of the injected voltage are significantly affected by the small fundamental current amplitude, leading to a substantial increase in noise introduced by current sampling and dead-zone voltage drop. Under the influence of temperature, voltage, speed, and torque variations, the deviation between the open-loop pre-injection amount and the actual compensation required after changes in environmental conditions is substantial, resulting in a loss of cancellation effectiveness to some extent. Since harmonic cancellation requires extremely high phase accuracy, a phase deviation exceeding 30° generally reduces the cancellation effect to below 50%, and a phase deviation approaching 180° can actually amplify harmonics. At low speeds and light loads, the resolver position pulsation error is large, and the complex and significant harmonic order makes it difficult for the phase of the injected harmonics to accurately match the required cancellation harmonics. This mismatch in cancellation can actually reduce the suppression effect or even have the opposite effect.

[0023] In summary, due to the characteristics of high coupling, high proportion, asymmetry, and complex order of harmonic currents in motors under low-speed and light-load conditions, and the differences in assembly processes of different motors leading to consistency issues, the cogging torque compensation scheme and the open-loop injection voltage scheme have relatively weak harmonic current suppression effects under low-speed and light-load conditions.

[0024] This invention provides a harmonic current suppression method. By introducing a three-step suppression scheme based on self-learning dynamic calibration, three-phase asymmetric dead zone compensation, and bandwidth enhancement proportional resonant control algorithm, it can suppress noise caused by first-order harmonic currents under low speed and light load conditions, as well as high-order current noise, and has a good current harmonic suppression effect.

[0025] According to an embodiment of the present invention, a method for suppressing harmonic current is provided. It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions. Furthermore, although a logical order is shown in the flowchart, in some cases, the steps shown or described may be executed in a different order than that shown here.

[0026] This embodiment provides a harmonic current suppression method, which can be used in the motor control system of new energy vehicles. Figure 1 This is a flowchart of a harmonic current suppression method for low-speed, light-load operating conditions of a new energy vehicle motor according to an embodiment of the present invention, such as... Figure 1 As shown, the process includes the following steps: Step S100: Acquire the sine envelope signal and cosine envelope signal of the rotary transformer, and perform self-learning dynamic calibration on the amplitude and bias of the sine envelope signal and cosine envelope signal so that the output current signal becomes the first current signal.

[0027] Specifically, a resolver is an electromagnetic sensor used to measure the angular displacement and angular velocity of a rotating object's axis; it can be simply called a resolver. In practical implementation, it is combined with... Figure 2 First, step S100 is executed in the preprocessing stage 100. For example, when performing position decoding in the motor soft decoding signal preprocessing part, the amplitude and bias of the acquired resolver's sinusoidal envelope signal (i.e., sin envelope signal) and cosine envelope signal (i.e., cos envelope signal) are dynamically calibrated through self-learning to eliminate the severe second harmonics caused by the three-phase asymmetry due to resolver sampling deviation. Self-learning dynamic calibration is to eliminate the consistency problems caused by the motor assembly process, which in turn lead to the deviation between motors.

[0028] Step S200: Dead zone compensation is performed using a three-phase asymmetrical dead zone compensation method, so that the output current signal changes from the first current signal to the second current signal.

[0029] Specifically, three-phase asymmetric dead-zone compensation can be performed using voltage-based real-time compensation, with compensation for each phase dead-zone performed separately. In practice, after step S100 is executed, step S200 is executed in the modulation stage 200. For example, in the stage of space vector pulse width modulation (SVPWM) controlling the inverter, by performing asymmetric dead-zone compensation on the three phases, the phase imbalance caused by the asymmetric voltage drop in the motor can be further eliminated, and the 3rd harmonic and most of the 11th and 13th harmonics can be effectively eliminated.

[0030] In step S300, an adjustment voltage is accumulated on the output voltage of the current loop, so that the output current signal changes from the second current signal to the final current signal. The adjustment voltage is output by an improved proportional resonant control algorithm, which is an improved algorithm with enhanced bandwidth.

[0031] Specifically, the current loop is implemented based on a proportional-integral (PI) controller. The current loop can include a direct-axis current loop (d-axis current loop) and a quadrature-axis current loop (q-axis current loop). In practice, after executing step S200, step S300 is executed in the voltage input stage 300. For example, a bandwidth-enhanced second-order generalized integral improved closed-loop proportional resonant controller (PR controller) is connected in parallel with both the d-axis and q-axis current loops, with the resonant point set to 6 times the electric angular velocity of the motor. This eliminates the remaining 3rd, 5th, and 7th harmonics, while also suppressing the remaining 11th and 13th harmonics. The PR controller is equipped with the improved proportional resonant control algorithm described in step S300.

[0032] The harmonic current suppression method provided in this embodiment, by acquiring the sinusoidal and cosine envelope signals of the rotary transformer and performing self-learning dynamic calibration on the amplitude and bias of the sinusoidal and cosine envelope signals, can essentially eliminate the second harmonic current of the motor under low speed and light load, that is, the second harmonic current is basically eliminated in the first current signal; by using three-phase asymmetrical dead-zone compensation, the third harmonic current under low speed and light load can be suppressed to a certain extent, and the amplitudes of the 11th and 13th harmonic currents are significantly reduced, that is, the second current signal... This method not only essentially eliminates the second harmonic current but also effectively suppresses the third, 11th, and 13th harmonic currents. An regulated voltage is accumulated on the current loop output voltage, output by an improved proportional-resonant control algorithm. This algorithm, with its enhanced bandwidth, achieves closed-loop harmonic suppression, effectively reducing the amplitudes of the remaining 3rd, 5th, 7th, 11th, and 13th harmonic currents to very low levels. In other words, noise caused by order harmonic currents and higher-order current noise in the final current signal is suppressed. The harmonic current suppression method provided in this embodiment exhibits excellent current harmonic suppression performance.

[0033] In some alternative implementations, such as Figure 3 Step S100 includes: Step S110: After power-on, once the amplitude and frequency of the excitation signal output by the controller to the rotary transformer are fixed, two arrays with preset index lengths are used as moving sampling windows to collect the amplitude and bias of the sine envelope signal and the cosine envelope signal, respectively. Step S120: The amplitudes of the sine envelope signal and the cosine envelope signal are extracted using a dynamic mean method to obtain the dynamically calculated amplitude values. Step S130: Obtain the bias of the sine envelope signal and the cosine envelope signal by subtracting the peaks and troughs and then averaging them, and obtain the dynamically calculated bias value. Step S140: Perform dynamic averaging on the dynamically obtained amplitude value and the dynamically obtained bias value to obtain the dynamic calibration value of amplitude and the dynamic calibration value of bias. Step S150: Before the controller initialization is complete, save the amplitude dynamic calibration value and the bias dynamic calibration value to the chip's memory; Step S160: Upon power-on again, read the stored amplitude dynamic calibration value and bias dynamic calibration value from the memory, and perform self-learning dynamic calibration with the dynamically obtained values ​​during the power-on initialization process.

[0034] Specifically, in this embodiment, the amplitude and bias of the sin envelope signal and cos envelope signal are calibrated. The main purpose is to eliminate the second harmonic current caused by the three-phase asymmetry due to deviations in angle amplitude and phase. The second harmonic current is most likely to be generated under low-speed and light-load conditions of the motor. Under low-speed and light-load conditions, the fundamental amplitude of the motor output current is small, the noise introduced by current sampling, dead-zone voltage drop, etc. increases significantly, the resolver position pulsation error is large, the motor back EMF is low at low speed, and the control disturbance rejection is weak. These factors lead to severe three-phase asymmetry in the motor control system, which in turn generates a phase current with a negative sequence disturbance of 1, forming a second harmonic current, i.e., the second harmonic of the phase current.

[0035] In this embodiment, the controller can be understood as a motor controller used to control the operation of the motor. Self-learning dynamic calibration of the amplitude and bias of the sin and cos envelope signals refers to the process after power-on, waiting for the controller to stabilize at low voltage, determining that the amplitude and frequency of the excitation signal output by the resolver are fixed, and then triggering sampling. Two arrays with a preset index length (e.g., index length 100) are used as moving sampling windows to collect the amplitude and bias of the sin and cos envelope signals respectively. The data update of the moving sampling windows adopts a stacked first-in-first-out (FIFO) format, effectively avoiding the drawback of sample loss during fixed-period data updates. The amplitudes of the sin and cos envelope signals are extracted using dynamic averaging. The bias is obtained by subtracting the peaks and troughs and then averaging. Finally, the dynamically calculated amplitude and bias values ​​obtained through the two moving sampling windows are dynamically averaged. Before the controller initialization is complete, the obtained dynamic amplitude calibration values ​​and dynamic bias calibration values ​​are stored in the chip's memory. Simultaneously, based on these values, the amplitude and bias of the sine and cosine envelope signals are calibrated. The memory can be an EEPROM (Electrically Erasable Programmable Read-Only Memory). Upon power-up, a self-learning dynamic calibration is performed based on the dynamic amplitude calibration values ​​and dynamic bias calibration values ​​in the memory (such as EEPROM). This not only filters out outliers but also effectively eliminates resolver consistency issues between motors caused by assembly processes.

[0036] In some optional implementations, during dead zone compensation, the compensation value and compensation rate for each phase of the three-phase asymmetry dead zone are dynamically calibrated online until the degree of three-phase asymmetry is reduced.

[0037] Specifically, in this embodiment, when using three-phase asymmetric dead zone compensation, the compensation value and compensation rate for each phase dead zone are dynamically calibrated online until the second and third orders of phase current are significantly improved, that is, the degree of three-phase asymmetry in the motor control system is reduced.

[0038] It should be noted that in the control circuit of an AC synchronous motor with a star connection and no center line, the ideal third harmonic is a zero-sequence component. According to Kirchhoff's laws and the structure of the motor with a star connection and no center line, there is no effective loop for the zero-sequence current to flow, therefore a truly pure zero-sequence third harmonic cannot be formed. In this embodiment, the third harmonic monitored by the oscilloscope in Fast Fourier Transform mode under low-speed and light-load conditions is a positive-sequence and negative-sequence third harmonic caused by asymmetric distortion, modulation distortion, and saturation distortion.

[0039] In some optional implementations, the inputs to the proportional resonance control algorithm include direct-axis current error, quadrature-axis current error, and a proportional resonance term. The outputs of the proportional resonance control algorithm include direct-axis adjustment voltage and quadrature-axis adjustment voltage. The proportional resonance term is determined based on the electric angular velocity calculated after self-learning dynamic calibration and compensation.

[0040] Specifically, in combination Figure 2 and Figure 4 The PR controller used to implement the proportional-resonant control algorithm can be understood as a closed-loop control system with bandwidth enhancement, a second-order generalized integral improved bandpass filter, or a harmonic suppression closed-loop system, respectively, using table lookup for the d-axis current. and lookup table q-axis current Given the actual d-axis and q-axis currents (i.e., d-axis feedback currents) after undergoing Clark and Park transformations, and q-axis feedback current This serves as feedback, forming a closed-loop control. The d-axis current is referenced from a table. and lookup table q-axis current The error is obtained from the Idq table using a lookup method. The direct-axis current error is determined by looking up the d-axis current table. and d-axis feedback current The quadrature-axis current error is obtained by referring to the table for the q-axis current. and q-axis feedback current The proportional resonance term can be set to 6 times the electric angular velocity of the motor. That is, the proportional resonance term is set to The current loop output voltage includes the direct-axis output voltage of the current loop. and current loop cross-axis output voltage Direct-axis voltage adjustment and cross-axis regulating voltage Accumulated to the output of the current loop (current loop direct-axis output voltage) and current loop cross-axis output voltage The final control voltage (direct-axis control voltage) is formed on the axis. and quadrature axis control voltage The harmonic suppression closed-loop system in this embodiment does not require coordinate transformation of high-order currents, nor does it require extraction of high-order currents. It also does not require distinguishing between the positive and negative sequences of harmonic currents, which simplifies the program implementation and helps save computing power.

[0041] In some alternative implementations, the closed-loop transfer function of the proportional resonant control algorithm is based on the resonant bandpass filter transfer function with the addition of a damping coefficient, a resonant gain coefficient, and a proportional coefficient.

[0042] Specifically, the transfer function of an ideal resonant bandpass filter can be expressed by the following formula: ; in, For the Laplace transform of the output signal, The Laplace transform of the input signal (error signal), For the differential factor, It is the resonant angular frequency, i.e., the electric angular velocity.

[0043] In this embodiment, the closed-loop transfer function of the proportional resonance control algorithm is obtained by adding a damping term coefficient to the denominator of the transfer function of the ideal resonant bandpass filter. This increases the resonant cutoff bandwidth. In other words, it extends the high-gain range to the resonant angular frequency. Centered on a specific cutoff frequency, the amplitude is broadened to maintain high gain throughput for the input signal within a certain frequency range. Simultaneously, to ensure the fundamental function of high gain at the resonant angular frequency, the numerator must also possess a damping coefficient. Thus, when the input signal is At that time, that is At this time, the denominator When the value equals 0, the damping coefficient can be canceled out in both the numerator and denominator. At the same time, to ensure high gain, the resonant gain coefficient needs to be increased in the molecule. This is to ensure the high-pass characteristics of the resonance. The resonant gain at this point is... The gain is no longer infinite. For practical engineering applications, zero-steady-state-error tracking does not require infinite gain. However, to ensure fast tracking and zero amplitude attenuation, a proportional term coefficient can be added to the resonant term, i.e. This completes the improvement of the resonant filter. The improved resonant filter retains the high gain characteristics of a resonant filter while also widening the system bandwidth, reducing the system's susceptibility to oscillation and divergence, and improving the system's robustness and reliability. It can effectively address the urgent problem of high harmonic content in the current of hub motors under low speed and light load conditions.

[0044] In this embodiment, the closed-loop transfer function of the proportional resonance control algorithm, namely the improved bandwidth-enhanced second-order generalized integral improved closed-loop PR proportional resonance algorithm, is expressed by the following formula: ; in, For the Laplace transform of the output signal, The Laplace transform of the input signal (error signal), For the differential factor, This is the proportional term coefficient, also known as the proportional term gain (equivalent to the proportional gain in a PI controller). This is the resonant gain coefficient, also known as the resonant term gain (which determines the peak gain at the resonant point). The cutoff frequency, The resonant angular frequency is the electrical angular velocity (which is consistent with the angular frequency of the sinusoidal signal to be tracked). It is used to broaden the frequency range of high-gain operation, reduce the risk of system oscillation, suppress system divergence, and improve the stability of resonant systems.

[0045] In some alternative implementations, the closed-loop transfer function is discretized into several mathematical branches by first reducing its order and then merging like terms. Each mathematical branch is discretized to differential, integral, or constant form.

[0046] Specifically, when applying the closed-loop transfer function to the harmonic current suppression method in this embodiment, the closed-loop transfer function needs to be discretized. For example, it can be converted into a difference equation or subjected to effective difference. In this embodiment, the closed-loop transfer function is discretized by first reducing its order and then merging like terms, until each simplified mathematical branch is discretized to only have differentials, integrals, and constants. The conversion process is as follows: First, the closed-loop transfer function is transformed using a polynomial, resulting in the following formula: ; Then reduce the order: ; Then transform the polynomial: ; Combining polynomials: ; Combine polynomials again: ; Combine the polynomials again and simplify until each term retains its integral or differential (e.g.) Figure 5 The final formula is expressed as follows: .

[0047] In some alternative implementations, the direct-axis regulating voltage and the quadrature-axis regulating voltage are low-pass filtered voltages.

[0048] For details, please refer to Figure 4 The PR controller is configured with an improved bandwidth-enhanced second-order generalized integral PR proportional resonance algorithm, which belongs to the resonance term. In order not to affect the basic function of suppressing low-order harmonic currents, and to eliminate high-frequency noise that may be introduced by the improvement, a first-order low-pass filter can be connected in series with the resonance term for low-pass filtering.

[0049] To verify the specific role of the harmonic current suppression method in this embodiment, we take the troubleshooting and resolution of the problem of severe current distortion, order vibration and noise in a hub motor under low speed and light load (45rpm, 80Nm) conditions on a dynamometer bench as an example.

[0050] The hub motor has a peak speed of 1500 rpm, a peak torque of 1400 Nm, a peak power of 120 kW, 20 pole pairs, and a rated voltage of 435 V. The experimental environment is a dynamometer bench. The experimental equipment includes: hub motor and controller, INCA (Integrated Calibration and Application Platform), oscilloscope with fast Fourier transform function, power analyzer, Rogowski coil current sensor, voltage sensor, torque sensor, towed dynamometer bench, 12V DC regulated power supply, energy-absorbing high-voltage power supply, cooling water supply equipment, NVH noise and vibration acquisition equipment, etc.

[0051] Based on the above experimental conditions, the dynamometer stand was driven to a low speed of 45 rpm to rotate the hub motor. The hub motor switch was given a steady-state torque of 80 Nm to conduct the experiment, thereby introducing the specific implementation plan of the harmonic current suppression method in this embodiment.

[0052] The first step, under the aforementioned bench conditions, involved online calibration using INCA. First, self-learning dynamic calibration was disabled, and manual calibration was performed to obtain accurate values. Then, power was restored, and self-learning dynamic calibration was re-enabled via INCA. The amplitude and bias of the resolver's output sin and cos envelope signals were monitored in real time, and the values ​​obtained from manual calibration and self-learning dynamic calibration were compared. Verification showed that the self-learning dynamic calibration values ​​were accurate, and observation of the fast Fourier decomposition of the phase current on an oscilloscope revealed that the second harmonic disappeared after self-learning dynamic calibration (e.g., ...). Figure 7 The experimental results can be compared. Figure 6 and Figure 7 .

[0053] The second step, maintaining the above operating conditions, involves online calibration of the dead-zone compensation using INCA. The slope and limit of the dead-zone compensation are set to the same value and then to different values. When setting different values, the changes in the harmonic current content of each order after fast Fourier decomposition of the phase current are dynamically observed on an electronic oscilloscope. Only when the harmonic current content of a certain order changes can the calibration step size be further adjusted to determine the calibration direction that reduces the harmonic current and to achieve the optimal result. After performing asymmetrical dead-zone compensation (such as...), Figure 8 The 11th and 13th harmonic currents were significantly reduced, and the experimental results can be compared. Figure 7 and Figure 8.

[0054] Third, maintaining the above operating conditions, first disable the bandwidth-enhanced second-order generalized integral improved closed-loop PR proportional resonant algorithm using INCA, then enable the algorithm to limit the amplitude of the suppressed voltage components on the d-axis and q-axis of the output to between -5V and 5V. This avoids abnormal output values ​​due to improper parameter adjustment. The adjustment parameter is: proportional term coefficient. Resonant gain coefficient Cutoff frequency The general rule for parameter adjustment is: and The larger the coefficient, the better the suppression effect of harmonic current. In specific adjustments, it should be based on... The adjustment of the value is the main focus, but the two coefficients cannot be increased indefinitely beyond an order of magnitude, the gain coefficient ( and An excessively large cutoff frequency can cause system oscillations and introduce high-frequency noise. It should not be too small or too large. Cutoff frequency Too small a value will result in an excessively small suppression range for the algorithm. Cutoff frequency Excessive interference can cause severe divergence in the phase current after harmonic suppression, and also introduce high-frequency vibration noise. When the three parameters are optimally modulated, they are fixed into the program. The harmonic suppression algorithm is first disabled via INCA, and then re-enabled. The effects before and after the algorithm is applied are compared. Figure 8 and Figure 9 As shown, after the algorithm was applied, the remaining 3rd, 5th, 7th, 11th, and 13th harmonics were almost completely suppressed, demonstrating a very significant effect in suppressing harmonic currents.

[0055] Comparing the phase current before any harmonic suppression measures were applied with the phase current after implementing the three-step harmonic current suppression method in this embodiment, as follows: Figure 10 As shown, the dead zone clamping of the phase current at the zero crossing point and the clamping effect near the peaks or troughs are significantly improved. The holding effect of the phase current at the clamping point is weakened, the distortion at the peaks and troughs is eliminated, the sinusoidal nature of the phase current is significantly increased, and the overall current waveform does not diverge.

[0056] To further verify the specific role of the harmonic current suppression method in this embodiment, we will take the investigation and resolution of the obvious order vibration and noise problem of a hub motor under the vehicle creeping condition as an example.

[0057] The hub motor has a peak speed of 1500 rpm, a peak torque of 1400 Nm, a peak power of 120 kW, and 20 pole pairs. The vehicle's high-voltage power supply is 435 V. The test environment was a full-vehicle crawl test environment. The test equipment included: a full vehicle equipped with the hub motor and controller, INCA (Integrated Vehicle Automation) system, NVH (Noise, Vibration, and Harshness) acquisition equipment, etc.

[0058] A whole-vehicle creep test was conducted under the above conditions to introduce the specific implementation plan of the harmonic current suppression method in this embodiment.

[0059] The first step, under full vehicle conditions, involves engaging drive without pressing the accelerator, allowing the vehicle to crawl in a controlled environment. The test should ideally be conducted on a smooth, flat asphalt surface to minimize the impact of tire and wind noise on the test results. Vibration and NVH noise acquisition devices are installed on the stator housing of the wheel hub motor, the passenger-side headrest, and the rear seat headrests. Using INCA, the three-stage harmonic suppression schemes in this embodiment are first disabled, and the self-learning dynamic calibration strategy for the resolver amplitude and bias is enabled. This allows for a sensory assessment of whether vibration and noise have improved. Simultaneously, vibration and noise data are collected. After collecting a complete cycle of data, the vibration and noise data are sliced, extracting the order noise and torque noise in the tangential, radial, and axial directions, primarily observing whether there is improvement in the second harmonic current noise data.

[0060] The second step is to maintain the vehicle's creeping driving condition and solidify the procedure from the first step. Then, the asymmetric dead zone compensation is turned off online via INCA, and the three-phase identical dead zone compensation is used by default. The asymmetric dead zone compensation strategy is then turned on again. First, the vibration and noise are compared sensorily to see if there is any improvement. At the same time, the vibration and noise data are collected with the asymmetric dead zone compensation turned off and on. The main observation is whether the 11th and 13th harmonic current noise data are improved before and after the asymmetric dead zone compensation switch is turned on.

[0061] The third step involves maintaining the vehicle in a crawling driving condition. Building upon the procedures from the first and second steps, the three main parameters of the bandwidth-enhanced second-order generalized integral improved closed-loop PR proportional resonance algorithm are calibrated online using INCA. Since high-precision sampling of the phase current is not possible under full-vehicle conditions, the proportional coefficients on the test bench must be referenced. Resonant gain coefficient and cutoff frequency The adjustment mechanism involves adjusting these three parameters based on sensory feedback under vehicle creep conditions. Ideally, the default values ​​should be set to the optimal parameters calibrated on the test bench. Fine-tuning on the vehicle should also revolve around these optimal parameters. Once the parameters are optimal, they are then embedded into the program. Next, the bandwidth-enhanced second-order generalized integral improved closed-loop PR proportional resonance algorithm is sequentially turned on and off online using INCA. Again, the improvement in vibration and noise is compared sensorily. Simultaneously, vibration and noise data are collected with and without the algorithm, primarily observing whether there is improvement in the remaining 3rd, 5th, 7th, 11th, and 13th harmonic current noise data before and after the proportional resonance algorithm is turned on.

[0062] Comparing the three-phase circuit order noise and torque noise in the tangential, radial, and axial directions after implementing the three-step harmonic current suppression method in this embodiment without any harmonic suppression measures, such as... Figure 11 and Figure 12 As shown, the harmonic current suppression method in this embodiment has a significant harmonic current suppression effect. Figure 11 The attached diagram on the left shows that, with the three-step harmonic current suppression scheme in this embodiment disabled, the order noise caused by the 2nd, 3rd, 5th, 7th, 11th, 13th, and higher-order harmonic currents is very noticeable. (See attached diagram.) Figure 11 The attached chart on the right shows the three-step harmonic current suppression scheme in this embodiment. Except for the fundamental current, noise caused by order harmonic currents disappears, and higher-order current noise also disappears. Figure 12 The attached diagram on the left shows the three-step harmonic current suppression scheme in this embodiment. With the tangential torque direction disabled, noise caused by the order current is severe. Noise in the radial and axial torque directions is not significant, but these two directions are not the primary directions for determining NVH noise issues. Figure 12 The attached diagram on the right shows the three-step harmonic current suppression scheme in this embodiment. The noise caused by the order current in the torque tangential direction is partially eliminated and significantly reduced. The noise in the torque radial and axial directions is also reduced.

[0063] This embodiment also provides a harmonic current suppression device for implementing the above embodiments and preferred embodiments; details already described will not be repeated. As used below, the term "module" can refer to a combination of software and / or hardware that performs a predetermined function. Although the devices described in the following embodiments are preferably implemented in software, hardware implementation, or a combination of software and hardware, is also possible and contemplated.

[0064] This embodiment provides a harmonic current suppression device, such as... Figure 13 As shown, it includes: The preprocessing module 10 is used to acquire the sinusoidal envelope signal and cosine envelope signal of the rotary transformer, and to perform self-learning dynamic calibration on the amplitude and bias of the sinusoidal envelope signal and cosine envelope signal so that the output current signal becomes the first current signal. The modulation processing module 20 is used to perform dead zone compensation by means of three-phase asymmetric dead zone compensation, so that the output current signal is changed from the first current signal to the second current signal. The input processing module 30 is used to accumulate the adjustment voltage on the current loop output voltage, so that the output current signal changes from the second current signal to the final current signal. The adjustment voltage is output by an improved proportional resonance control algorithm, which is an improved algorithm with enhanced bandwidth.

[0065] The harmonic current suppression device provided in this embodiment of the invention can execute the harmonic current suppression method provided in any embodiment of the invention, and has the corresponding functional modules and beneficial effects for executing the method. Further functional descriptions of the various modules and units described above are the same as in the corresponding embodiments described above, and will not be repeated here.

[0066] Figure 14 This is a schematic diagram of the structure of an electronic device provided in an embodiment of the present invention.

[0067] The following is a detailed reference. Figure 14 The diagram illustrates a structural schematic suitable for implementing an electronic device according to embodiments of the present invention. The electronic device may include a processor (e.g., a central processing unit, graphics processor, etc.) 101, which can perform various appropriate actions and processes according to a program stored in read-only memory (ROM) 102 or a program loaded from memory 108 into random access memory (RAM) 103. The RAM 103 also stores various programs and data required for the operation of the electronic device. The processor 101, ROM 102, and RAM 103 are interconnected via a bus 104. An input / output (I / O) interface 105 is also connected to the bus 104.

[0068] Typically, the following devices can be connected to I / O interface 105: input devices 106 including, for example, touchscreens, touchpads, keyboards, mice, cameras, microphones, accelerometers, gyroscopes, etc.; output devices 107 including, for example, liquid crystal displays (LCDs), speakers, vibrators, etc.; memory devices 108 including, for example, magnetic tapes, hard disks, etc.; and communication devices 109. Communication device 109 allows electronic devices to communicate wirelessly or wiredly with other devices to exchange data. Although Figure 14 Electronic devices with various devices are shown, but it should be understood that it is not required to implement or have all of the devices shown, and more or fewer devices may be implemented or have instead.

[0069] In particular, according to embodiments of the present invention, the processes described above with reference to the flowcharts can be implemented as computer software programs. For example, embodiments of the present invention include a computer program product comprising a computer program carried on a non-transitory computer-readable medium, the computer program containing program code for performing the methods shown in the flowcharts. In such embodiments, the computer program can be downloaded and installed from a network via a communication device 109, or installed from a memory 108, or installed from a ROM 102. When the computer program is executed by the processor 101, it performs the functions defined in the harmonic current suppression method of the embodiments of the present invention.

[0070] Figure 14 The electronic device shown is merely an example and should not be construed as limiting the functionality and scope of use of the embodiments of the present invention.

[0071] This invention also provides a computer-readable storage medium. The methods described above according to embodiments of the invention can be implemented in hardware or firmware, or implemented as computer code that can be recorded on a storage medium, or implemented as computer code downloaded via a network and originally stored on a remote storage medium or a non-transitory machine-readable storage medium and then stored on a local storage medium. Thus, the methods described herein can be processed by software stored on a storage medium using a general-purpose computer, a dedicated processor, or programmable or dedicated hardware. The storage medium can be a magnetic disk, optical disk, read-only memory, random access memory, flash memory, hard disk, or solid-state drive, etc.; further, the storage medium can also include combinations of the above types of memory. It is understood that computers, processors, microprocessor controllers, or programmable hardware include storage components capable of storing or receiving software or computer code. When the software or computer code is accessed and executed by the computer, processor, or hardware, the harmonic current suppression method shown in the above embodiments is implemented.

[0072] Although embodiments of the invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A harmonic current suppression method, applied to low-speed, light-load motor operation, characterized in that, include: The sinusoidal and cosine envelope signals of the rotary transformer are acquired, and the amplitude and bias of the sinusoidal and cosine envelope signals are dynamically calibrated through self-learning so that the output current signal becomes the first current signal. Dead zone compensation is performed by using a three-phase asymmetrical dead zone compensation method, so that the output current signal changes from the first current signal to the second current signal; An adjustment voltage is accumulated on the output voltage of the current loop, so that the output current signal changes from the second current signal to the final current signal. The adjustment voltage is output by an improved proportional resonance control algorithm, which is an improved algorithm with enhanced bandwidth.

2. The harmonic current suppression method according to claim 1, characterized in that, Acquire the sinusoidal and cosine envelope signals of the rotary transformer, and perform self-learning dynamic calibration on the amplitude and bias of the sinusoidal and cosine envelope signals, including: After power-on, once the amplitude and frequency of the excitation signal output by the controller to the rotary transformer are fixed, two arrays with preset index lengths are used as moving sampling windows to collect the amplitude and bias of the sine envelope signal and the cosine envelope signal, respectively. The amplitudes of the sine and cosine envelope signals are extracted using a dynamic averaging method to obtain dynamically calculated amplitude values. The bias of the sine and cosine envelope signals is obtained by subtracting the peaks and troughs and then averaging them, thus obtaining the dynamically calculated bias value. The dynamically calculated amplitude value and the dynamically calculated bias value are subjected to dynamic averaging processing to obtain the dynamic amplitude calibration value and the dynamic bias calibration value. Before the controller initialization is complete, the amplitude dynamic calibration value and the bias dynamic calibration value are saved to the chip's memory; Upon power-on again, the stored amplitude dynamic calibration value and bias dynamic calibration value are read from the memory and compared with the dynamically obtained values ​​during the power-on initialization process to perform self-learning dynamic calibration.

3. The harmonic current suppression method according to claim 1, characterized in that, During dead zone compensation, the compensation value and compensation rate for each phase of the three-phase asymmetry dead zone are dynamically calibrated online until the degree of three-phase asymmetry is reduced.

4. The harmonic current suppression method according to claim 1, characterized in that, The inputs of the proportional resonance control algorithm include direct-axis current error, quadrature-axis current error, and proportional resonance term. The outputs of the proportional resonance control algorithm include direct-axis adjustment voltage and quadrature-axis adjustment voltage. The proportional resonance term is determined based on the electric angular velocity calculated after self-learning dynamic calibration and compensation.

5. The harmonic current suppression method according to claim 4, characterized in that, The closed-loop transfer function of the proportional resonant control algorithm is based on the resonant bandpass filter transfer function with the addition of a damping coefficient, a resonant gain coefficient, and a proportional coefficient.

6. The harmonic current suppression method according to claim 5, characterized in that, When the closed-loop transfer function is discretized, it is first reduced in order and then like terms are combined to discretize it into several mathematical branches. Each mathematical branch is discretized to differential, integral or constant form.

7. The harmonic current suppression method according to claim 4, characterized in that, The direct-axis adjustment voltage and the quadrature-axis adjustment voltage are voltages that have undergone low-pass filtering.

8. A harmonic current suppression device, characterized in that, The device includes: The preprocessing module is used to acquire the sinusoidal envelope signal and cosine envelope signal of the rotary transformer, and to perform self-learning dynamic calibration on the amplitude and bias of the sinusoidal envelope signal and the cosine envelope signal, so that the output current signal becomes the first current signal. The modulation processing module is used to perform dead zone compensation by means of three-phase asymmetric dead zone compensation, so that the output current signal is changed from the first current signal to the second current signal. The input processing module is used to accumulate an adjustment voltage on the current loop output voltage, so that the output current signal changes from the second current signal to the final current signal. The adjustment voltage is output by an improved proportional resonance control algorithm, which is an improved algorithm with enhanced bandwidth.

9. An electronic device, characterized in that, include: A memory and a processor are communicatively connected, the memory storing computer instructions, and the processor executing the computer instructions to perform the harmonic current suppression method according to any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer instructions for causing a computer to perform the harmonic current suppression method according to any one of claims 1 to 7.

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