Permanent magnet synchronous motor current harmonic open-loop optimization method and device and medium

Abstract

The invention relates to a current harmonic open-loop optimization method and device of a permanent magnet synchronous motor and a medium, and the method comprises the following steps: injecting 6n-order harmonics of which the amplitude and phase can be calibrated into a rotor angle of the permanent magnet synchronous motor, n being a positive integer; when the rotating speed of the motor is out of the enabling interval, the 6n-th harmonic angle injection amplitude is linearly reduced to 0 in the buffering rotating speed interval; and when the rotating speed of the motor is in the enabling interval, the amplitude and phase angle of 6n-order harmonic waves are adjusted in real time according to the real-time torque, rotating speed and bus voltage of the permanent magnet synchronous motor, and current harmonic wave optimization is realized. Compared with the prior art, the method has the advantages of open-loop injection, simple parameter calibration, small CPU load and the like.

Description

Technical Field

[0001] The invention relates to the field of permanent magnet synchronous motor control, and in particular to a method, a device and a medium for optimizing current harmonics of a permanent magnet synchronous motor through an open loop. Background Art

[0002] Electric vehicles have developed rapidly in recent years, and permanent magnet synchronous motors have been widely used in the field of electric vehicles due to their high power density, low moment of inertia and high efficiency.

[0003] Motor controllers with high control performance and high reliability have become the current development trend. However, due to factors such as inverter nonlinearity and non-sinusoidal back EMF waveform, the permanent magnet synchronous motor windings will contain 5th and 7th harmonics, resulting in torque pulsation and affecting the stability of control. At the same time, current harmonics will also have varying degrees of adverse effects on important performance indicators such as NVH, EMC and system efficiency, thereby affecting the competitiveness of the product. In order to improve the current harmonic characteristics, the commonly used control optimization strategy is mainly multi-rotation PI control to inject or eliminate harmonic currents. This strategy has a relatively good harmonic suppression effect, but it requires multiple PI controllers, and parameter adjustment is more difficult. At the same time, its complexity will increase the CPU load.

[0004] Moreover, due to the limitation of high-speed weak magnetic voltage utilization, this method is not suitable for high-speed harmonic optimization. At the same time, as the speed increases, the number of sampling points decreases, and the harmonic characteristics are difficult to be accurately extracted and suppressed. Therefore, how to simplify the harmonic optimization strategy to reduce its impact on the CPU load and achieve better harmonic suppression effects in high-speed and even weak magnetic ranges has become the main research goal. Summary of the invention

[0005] The purpose of the present invention is to overcome the defects of the above-mentioned prior art and to provide a method, device and medium for optimizing the current harmonics of a permanent magnet synchronous motor in an open loop.

[0006] The purpose of the present invention can be achieved by the following technical solutions:

[0007] A method for optimizing the current harmonics of a permanent magnet synchronous motor in an open loop comprises the following steps:

[0008] A 6nth harmonic whose amplitude and phase can be calibrated is injected into the rotor angle of the permanent magnet synchronous motor, where n is a positive integer;

[0009] When the motor speed is outside the enabling range, the 6nth harmonic angle injection amplitude decreases linearly to 0 within the buffer speed range;

[0010] When the motor speed is within the enabling range, the amplitude and phase angle of the 6nth harmonic are adjusted in real time according to the real-time torque, speed and bus voltage of the permanent magnet synchronous motor to achieve current harmonic optimization.

[0011] Furthermore, the process of adjusting the amplitude and phase angle of the 6nth harmonic in real time is:

[0012] According to the torque, speed and bus voltage of the permanent magnet synchronous motor, the amplitude and phase of the harmonic angle are obtained by searching the 3D table of the amplitude and phase angle of the harmonic angle injection;

[0013] Obtain the rotor angle of the current sampling period, and calculate the harmonic angle to be injected by combining the amplitude and phase of the harmonic angle;

[0014] The harmonic angle to be injected is added to the rotor angle to obtain the control angle;

[0015] Use the control angle for current coordinate transformation and SVPWM.

[0016] Furthermore, the calculation expression of the harmonic angle to be injected is:

[0017] θ 6th =θ gain sin(6nθ sample +θ phase )

[0018] In the formula, θ 6th is the harmonic angle to be injected, θ gain is the amplitude of the harmonic angle, θ sample is the rotor angle of the current sampling period, θ phase is the phase of the harmonic angle.

[0019] Furthermore, the process of establishing the 3D table of amplitude and phase angle of harmonic angle injection is as follows:

[0020] Based on the existing data, select the harmonic angle injection amplitude, record the data of the three-phase current or NVH effect gradually changing with the phase angle of the 6nth harmonic, and perform three-phase current offline FFT analysis or NVH effect comparison to obtain the optimal phase angle;

[0021] The phase angle of harmonic angle injection is fixed as the optimal phase angle, and the data of the gradual change of three-phase current or NVH effect with the amplitude of 6n harmonic angle injection is recorded. Offline FFT analysis of three-phase current or comparison of NVH effect is performed to obtain the optimal injection amplitude.

[0022] Calibrate all operating points that require harmonic current optimization to obtain the optimal phase angle and optimal injection amplitude combination corresponding to each operating point;

[0023] According to the optimal phase angle and optimal injection amplitude combination corresponding to each operating point, a three-dimensional table of the amplitude and phase angle of the sixth harmonic angle injection related to the torque, speed and bus voltage is generated offline.

[0024] Furthermore, the three-phase current offline FFT analysis is specifically as follows: comparative analysis is performed on 6n-1 and 6n+1 harmonics.

[0025] Furthermore, the NVH effect comparison is specifically as follows: a comparative analysis is conducted on the 6n-order noise of the electrical frequency.

[0026] Furthermore, the phase angle of the sixth harmonic changes from 0° to 360°, with a change of 5° each time.

[0027] Furthermore, the amplitude variation process of the 6nth harmonic angle injection is: from 0.1° to the maximum value, each time changing by 0.1°.

[0028] A second aspect of the present invention is a device for optimizing the current harmonics of a permanent magnet synchronous motor of an automobile, comprising a memory, a processor, and a program stored in the memory, wherein when the processor executes the program, the device implements any of the above methods for optimizing the current harmonics of a permanent magnet synchronous motor.

[0029] A third aspect of the present invention is a storage medium having a program stored thereon, which, when executed, implements any of the above methods for open-loop optimization of current harmonics of a permanent magnet synchronous motor.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] 1) The present invention judges the harmonic angle injection effect through three-phase current FFT analysis or NVH effect. It only needs to calibrate the amplitude and phase of the harmonic angle injection. The parameter calibration method is simple, which is an open-loop injection method without the need for a PI closed loop, thus reducing the complexity of the system and having little impact on the CPU load.

[0032] 2) The present invention sets a rotation speed buffer to ensure the continuity of the switching between enabling and disabling the angle harmonic injection function.

[0033] 3) The present invention can inject the corresponding harmonic voltage into the output voltage without being affected by the voltage utilization limit. The technology can also reduce the 6nth harmonic of the dq axis current in the current control loop and improve the stability of the control. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a control block diagram of the present invention.

[0035] Figure 2 This is the linearization diagram of the harmonic angle amplitude in the speed buffer. DETAILED DESCRIPTION

[0036] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0037] Example 1

[0038] The present invention is a method for optimizing the harmonics of a permanent magnet synchronous motor current in an open loop. The method optimizes the fifth and seventh harmonics in the actual current by injecting the sixth harmonic of appropriate amplitude and phase into the rotor angle. Specifically,

[0039] Injecting the sixth harmonic with calibrable amplitude and phase into the rotor angle of the permanent magnet synchronous motor;

[0040] When the motor speed is outside the enabling range, the 6th harmonic angle injection amplitude decreases linearly to 0 within the buffer speed range;

[0041] When the motor speed is within the enabling range, the amplitude and phase angle of the sixth harmonic are adjusted in real time according to the real-time torque, speed and bus voltage of the permanent magnet synchronous motor to achieve current harmonic optimization.

[0042] like Figure 1 As shown in the figure, the process of real-time adjustment of the amplitude and phase angle of the sixth harmonic is:

[0043] According to the torque, speed and bus voltage of the permanent magnet synchronous motor, the amplitude and phase of the harmonic angle are obtained by searching the 3D table of the amplitude and phase angle of the harmonic angle injection;

[0044] Obtain the rotor angle of the current sampling period, and calculate the harmonic angle to be injected by combining the amplitude and phase of the harmonic angle;

[0045] The calculation expression of the harmonic angle to be injected is:

[0046] θ 6t h=θ gain sin(6θ sample +θ phase )

[0047] In the formula, θ 6th is the harmonic angle to be injected, θ gain is the amplitude of the harmonic angle, θ sample is the rotor angle of the current sampling period, θ phase is the phase of the harmonic angle.

[0048] The harmonic angle to be injected is added to the rotor angle to obtain the control angle;

[0049] Use the control angle for current coordinate transformation and SVPWM.

[0050] The injection process includes two parts: online injection and parameter calibration:

[0051] Online injection part:

[0052] Since the harmonic order response of the 5th and 7th harmonic characteristics in the three-phase current in the dq axis current is the 6th harmonic, the rotor angle participates in the coordinate transformation calculation. Therefore, injecting the 6th harmonic with scalable amplitude and phase into the rotor angle can optimize the actual voltage output and optimize the three-phase current. θ is the rotor angle obtained by real-time sampling, θ 6th is the injected 6th harmonic.

[0053] like Figure 2 As shown, in actual engineering, harmonic current suppression is often performed in a specific speed range. In order to ensure the continuity of the harmonic injection enabling range and the disabling range, a buffer speed range is added. In this range, the angle harmonic injection amplitude changes linearly. When the speed enters the disabling range from the enabling range, the harmonic angle injection amplitude decreases linearly to 0 in the buffer speed range.

[0054] Among them, the buffer speed range is set according to the specific project requirements, and the linearity depends on the range of the buffer speed range.

[0055] Parameter calibration part:

[0056] All operating points that require harmonic current optimization need to be calibrated. Since the parameter calibration method for different operating points is the same, the calibration process for the operating point is as follows:

[0057] Based on the existing data (based on engineering experience), the harmonic angle injection amplitude is selected, the phase angle is adjusted from 0° to 360°, and the data of the gradual change of the three-phase current or NVH effect with the phase angle of the sixth harmonic is recorded every 5°, and the three-phase current offline FFT analysis or NVH effect comparison is performed to obtain the optimal phase angle;

[0058] The phase angle of harmonic angle injection is fixed to the optimal phase angle, and the amplitude is adjusted from 0.1° to the maximum value (based on engineering experience). The data of the gradual change of the three-phase current or NVH effect with the amplitude of the sixth harmonic angle injection is recorded every 0.1°, and the three-phase current offline FFT analysis or NVH effect comparison is performed to obtain the optimal injection amplitude;

[0059] Calibrate all operating points that require harmonic current optimization to obtain the optimal phase angle and optimal injection amplitude combination corresponding to each operating point;

[0060] According to the optimal phase angle and optimal injection amplitude combination corresponding to each operating point, a three-dimensional table of the amplitude and phase angle of the sixth harmonic angle injection related to the torque, speed and bus voltage is generated offline.

[0061] Among them, FFT analysis mainly compares and analyzes the 5th and 7th harmonics that need to be optimized, and NVH mainly compares and analyzes the 6th order noise of the electrical frequency.

[0062] The present invention utilizes that the characteristics of current harmonics under fixed operating points are fixed, and the 5th and 7th harmonics are represented as 6th harmonics in the dq axis system, and the rotor angle participates in the current coordinate transformation and SVPWM modulation output, so the 6th harmonic angle can be injected into the rotor angle, thereby injecting the corresponding harmonic into the output voltage to optimize the current harmonic characteristics. As an open-loop optimization method, the present invention does not require a PI closed loop, reduces the complexity of the system, and has little impact on the CPU load.

[0063] Based on the method of the present invention, if one wants to optimize the 11th harmonic and the 13th harmonic in the three-phase, the 12th harmonic can be injected into the angle, and the harmonic order in the harmonic angle calculation formula is set to 12.

[0064] Example 2

[0065] On the basis of Example 1, the program code for implementing the method of the present invention can be written in any combination of one or more programming languages. These program codes can be provided to a processor or controller of a general-purpose computer, a special-purpose computer or other programmable data processing device, so that the program code, when executed by the processor or controller, enables the functions / operations specified in the flow chart and / or block diagram to be implemented. The program code can be executed entirely on the machine, partially on the machine, partially on the machine as a stand-alone software package and partially on a remote machine, or entirely on a remote machine or server.

[0066] In the context of the present invention, a machine-readable medium may be a tangible medium that may contain or store a program for use by or in conjunction with an instruction execution system, device, or equipment. A machine-readable medium may be a machine-readable signal medium or a machine-readable storage medium. A machine-readable medium may include, but is not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, devices, or equipment, or any suitable combination of the foregoing. A more specific example of a machine-readable storage medium may include an electrical connection based on one or more lines, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

[0067] The preferred specific embodiments of the present invention are described in detail above. It should be understood that a person skilled in the art can make many modifications and changes based on the concept of the present invention without creative work. Therefore, any technical solution that can be obtained by a person skilled in the art through logical analysis, reasoning or limited experiments based on the concept of the present invention on the basis of the prior art should be within the scope of protection determined by the claims.

Claims

1. A method for optimizing the current harmonics of a permanent magnet synchronous motor in an open loop, characterized in that: The following steps are involved: A 6nth harmonic whose amplitude and phase can be calibrated is injected into the rotor angle of the permanent magnet synchronous motor, where n is a positive integer; When the motor speed is outside the enabling range, the 6nth harmonic angle injection amplitude decreases linearly to 0 within the buffer speed range; When the motor speed is within the enabling range, the amplitude and phase angle of the 6nth harmonic are adjusted in real time according to the real-time torque, speed and bus voltage of the permanent magnet synchronous motor to achieve current harmonic optimization.

2. A permanent magnet synchronous motor current harmonic open-loop optimization method according to claim 1, characterized in that: The process of real-time adjustment of the amplitude and phase angle of the 6nth harmonic is as follows: According to the torque, speed and bus voltage of the permanent magnet synchronous motor, the amplitude and phase of the harmonic angle are obtained by searching the 3D table of the amplitude and phase angle of the harmonic angle injection; Obtain the rotor angle of the current sampling period, and calculate the harmonic angle to be injected by combining the amplitude and phase of the harmonic angle; The harmonic angle to be injected is added to the rotor angle to obtain the control angle; Use the control angle for current coordinate transformation and SVPWM.

3. A permanent magnet synchronous motor current harmonic open-loop optimization method according to claim 2, characterized in that: The calculation expression of the harmonic angle to be injected is: i 6t h=θ gain sin(6nθ sample +θ phase ) In the formula, θ 6th is the harmonic angle to be injected, θ gain is the amplitude of the harmonic angle, θ sample is the rotor angle of the current sampling period, θ phase is the phase of the harmonic angle.

4. A permanent magnet synchronous motor current harmonic open-loop optimization method according to claim 2, characterized in that: The process of establishing the 3D table of amplitude and phase angle of harmonic angle injection is as follows: Based on the existing data, select the harmonic angle injection amplitude, record the data of the three-phase current or NVH effect gradually changing with the phase angle of the 6nth harmonic, and perform three-phase current offline FFT analysis or NVH effect comparison to obtain the optimal phase angle; The phase angle of harmonic angle injection is fixed as the optimal phase angle, and the data of the gradual change of three-phase current or NVH effect with the amplitude of 6n harmonic angle injection is recorded. Offline FFT analysis of three-phase current or comparison of NVH effect is performed to obtain the optimal injection amplitude. Calibrate all operating points that require harmonic current optimization to obtain the optimal phase angle and optimal injection amplitude combination corresponding to each operating point; According to the optimal phase angle and optimal injection amplitude combination corresponding to each operating point, a three-dimensional table of the amplitude and phase angle of the 6nth harmonic angle injection related to the torque, speed and bus voltage is generated offline.

5. A method for optimizing the current harmonics of a permanent magnet synchronous motor in an open loop according to claim 4, characterized in that: The three-phase current offline FFT analysis specifically includes: performing comparative analysis on 6n-1 and 6n+1 harmonics.

6. A method for optimizing current harmonics of a permanent magnet synchronous motor in an open loop according to claim 4, characterized in that: The NVH effect comparison is specifically as follows: a comparative analysis is performed on the 6n-order noise of the electrical frequency.

7. A permanent magnet synchronous motor current harmonic open-loop optimization method according to claim 4, characterized in that: The phase angle of the sixth harmonic changes from 0° to 360°, with a change of 5° each time.

8. A method for optimizing current harmonics of a permanent magnet synchronous motor in an open loop according to claim 4, characterized in that: The amplitude variation process of the 6th harmonic angle injection is: from 0.1° to the maximum value, each time changing by 0.1°.

9. A current harmonic optimization device for a permanent magnet synchronous motor of an automobile, comprising a memory, a processor, and a program stored in the memory, characterized in that: When the processor executes the program, it implements a permanent magnet synchronous motor current harmonic open-loop optimization method as described in any one of claims 1-8.

10. A storage medium having a program stored thereon, characterized in that: When the program is executed, a permanent magnet synchronous motor current harmonic open-loop optimization method as described in any one of claims 1-8 is implemented.

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