Wheel hub motor high frequency harmonic suppression sensorless control system and method

Abstract

The application relates to the technical field of driving and equipment control, in particular to a position sensorless control system and method for wheel hub motor high-frequency harmonic suppression, output alpha-beta axis current i α 、 β After passing through a signal separation module, high-frequency alpha-beta axis current i αh 、 βh and low-frequency alpha-beta axis current signal i αl 、 βl are output, the alpha-beta axis current i αh 、 βh of the high-frequency signal and a rotor position estimation value are input into a rotor position error extraction module to extract errors and obtain a rotor position error epsilon; and the alpha-beta axis current signal i αl 、 βl of the low-frequency signal is input into a PARK conversion module to obtain gamma-delta reference axis current i δ 、 γ which is used for current closed-loop control. The application aims at the error harmonic problem caused by high-frequency signal injection and estimation, combines a dynamic circulation iteration strategy, introduces a forgetting factor, adjusts the estimated rotor position on line, realizes error signal harmonic suppression and compensation, and thus guarantees the performance stability of wheel hub motor position sensorless control.

Description

Technical Field

[0001] This invention relates to the field of drive and equipment control technology, and in particular to a sensorless control system and method for suppressing high-frequency harmonics in hub motors. Background Technology

[0002] With the development of advanced technologies and the depletion of non-renewable resources, electric vehicles (EVs) use batteries as their power source and electric motors to drive the vehicle, offering advantages such as low energy consumption and zero pollution. The rapid development of the EV industry has also driven advancements in motor drive and control technologies. Permanent magnet synchronous motors, asynchronous motors, and switched reluctance motors are all alternative drive solutions for EVs. Distributed motor drive technology, which mounts the drive motor on the wheels, offers advantages such as high transmission efficiency and reduced vehicle weight, and is therefore widely researched and applied.

[0003] In-wheel motors, installed on all four wheels, generate power within the wheels to drive the vehicle. This not only reduces the weight of traditional driveshafts, universal joints, and other transmission components but also provides faster torque response and more precise torque control. Therefore, distributed in-wheel motor drive systems represent a significant future trend in electric vehicle drive systems.

[0004] To achieve more reliable maneuverability, faster acceleration, and better stability in hub motor operation, research on motor controllers and control technologies is crucial. In actual motor operation, position sensors collect rotor position information for high-performance motor control. However, harsh environments such as high temperatures and humidity can cause sensor malfunctions or even damage, severely impacting motor speed control performance and reducing operational stability. Furthermore, installing high-precision position sensors not only increases the cost of the electric drive system but also its size and complexity. Therefore, research into sensorless control technology for hub motors is essential.

[0005] Currently, there are two main types of sensorless control strategies for permanent magnet hub motors: when the motor is running at high speed, rotor position information is extracted through the back electromotive force or stator current signal; while when the motor is running at low speed, the rotor position information is difficult to obtain directly due to the weak back electromotive force and current signal, so a high-frequency signal injection method is usually adopted. This involves superimposing a high-frequency voltage or current signal onto the motor's own voltage or current signal, then extracting position information from the current signal after the motor's response and filtering it with an appropriate filter, and finally using an error algorithm to estimate the rotor position. However, the use of artificial high-frequency signal injection inevitably introduces high-frequency signal interference. At the same time, due to the nonlinearity of the motor and the coupling characteristics of the motor's magnetic field and current, the current and rotor position signals after the response will generate certain high-order harmonics.

[0006] The existing patent application number "201910825097.2" addresses a sensorless low-speed motor control method, employing a novel pulse high-frequency signal injection method and using a linearized algorithm for high-frequency response signal separation. However, it does not consider the high-order harmonics generated in the rotor position signal during pulse high-frequency signal injection and rotor position estimation. The presence of these high-order harmonics not only reduces the accuracy of rotor position estimation but also leads to a decrease in motor speed regulation performance. Summary of the Invention

[0007] To address the shortcomings of existing algorithms, this invention addresses the error harmonics caused by high-frequency signal injection and estimation in current sensorless control strategies for hub motors. Based on traditional high-frequency signal injection methods and rotor position estimation and extraction methods, it combines a dynamic iterative strategy and introduces a forgetting factor to adjust the estimated rotor position online, thereby suppressing and compensating for error signal harmonics and ensuring the stable performance of sensorless control of hub motors.

[0008] The technical solution adopted in this invention is as follows: The sensorless control system for high-frequency harmonic suppression of hub motors consists of a permanent magnet hub motor system, a rotor position error extraction module, a rotor position information calculation module, a rotor position harmonic dynamic suppression module, a signal separation module, and a PARK conversion module connected in series. The αβ axis current i output by the permanent magnet hub motor system... α i β After passing through the signal separation module, a high-frequency αβ axis current i is output. αh i βh and low-frequency αβ axis current signal i αl i βl αβ axis current i of high frequency signal αh i βh and rotor position estimate The input is fed to the rotor position error extraction module for error extraction to obtain the rotor position error ε; while the low-frequency signal αβ axis current signal i αl i βl The input is then given to the PARK transformation module to obtain the γδ reference axis current i. δ i γ Used for current closed-loop control.

[0009] Furthermore, the permanent magnet hub motor system consists of a PARK inverter module, an SVPWM modulation module, a three-phase inverter module, a permanent magnet hub motor, and a CLARK converter module connected in series, with a reference voltage for injecting a high-frequency signal along the γδ reference axis. and rotor position estimate As the input to the PARK inverse transformer module, the output is the αβ axis reference voltage. And it serves as the input to the SVPWM modulation module, which outputs a three-phase voltage u. abc This serves as the input to the three-phase inverter module, which outputs a three-phase current i. abc ; and serves as the input to the permanent magnet hub motor and the CLARK converter module, with the CLARK converter module outputting the αβ axis current i α i β .

[0010] Furthermore, the rotor position error extraction module consists of a PARK transformation module, a first low-pass filter, and a per-unit module. The PARK transformation module uses the αβ axis current i of the high-frequency signal. αh i βh and rotor position estimate As input, the output γδ reference axis high-frequency current i γh i δh The expression is:

[0011]

[0012] Among them, i γh i δh For the high-frequency current of the γδ reference axis, i αh i βh For αβ axis current;

[0013] i γh i δh The high-frequency signal in the input current is filtered by the first low-pass filter to obtain the low-frequency current i′. γh 、i′ δh The current signal is then input to the per-unit module for per-unit processing to obtain the rotor position error ε, which is expressed as:

[0014]

[0015] Where, i′ γh 、i′ δh It is a low-frequency current.

[0016] Furthermore, the rotor position information calculation module uses the rotor position error ε and the high-frequency current error compensation value ΔI. c As input, the two signals are summed and then passed through two adjustment modules. Finally, a second low-pass filter module is used to filter the high-frequency signal, thereby obtaining the speed estimate. Rotor position estimation value The estimated rotational speed is obtained by using an integral module, and the expression is:

[0017]

[0018] Where, k p k i These are the gain values ​​of the adjustment module, ε is the rotor position error, and ΔI is the gain value of the adjustment module. c This is the high-frequency current error compensation value. This is an estimated value for the rotational speed. This is the estimated rotor position.

[0019] Furthermore, the rotor position harmonic dynamic suppression module uses the speed reference value Speed ​​estimate Using the two signals as input, the difference is calculated to obtain the rotor speed estimation error. The rotor speed estimation error, after passing through a dynamic integration module and time-varying iterative gains Γ(t) and Φ(t), is compared with the high-frequency current error compensation value ΔI. c The feedback gain value is used for cyclic compensation, and the expression is:

[0020]

[0021] Where Γ(t) and Φ(t) are time-varying iterative gains, and ΔI c (t) represents the high-frequency current error compensation value; λ is the forgetting factor; X is the average error evaluation function, k p1 k i1 With k p2 k i2 These are the PI adjustment parameter values ​​for the time-varying iterative gain functions Γ(t) and Φ(t), respectively.

[0022] Furthermore, the method for a sensorless control system for high-frequency harmonic suppression of hub motors includes the following steps:

[0023] Step 1: Inject a high-frequency signal into the γδ reference shaft voltage and input it to the permanent magnet hub motor system, outputting the αβ shaft current i. α i β ;

[0024] Step 2: Convert the αβ axis current i α i β The input is fed into the signal separation module to obtain the high-frequency αβ axis current i. αh i βh and low-frequency αβ axis current signal i αl i βl ;

[0025] Step 3: Convert the αβ axis current i of the high-frequency signal αh i βh and rotor position estimate The rotor position error is input into the rotor position error extraction module to obtain the rotor position error ε;

[0026] Step 4: Compensate the rotor position error ε and the high-frequency current error value ΔI output by the rotor position harmonic dynamic suppression module. c The accumulated values ​​are then input into the rotor position information calculation module to obtain the rotor position estimate. Speed ​​estimate

[0027] Step 5: Set the speed reference value Speed ​​estimate The input is fed into the rotor position harmonic dynamic suppression module to obtain the high-frequency current error compensation value ΔI. c This leads to the cyclical iterative suppression and compensation of rotor position estimation error.

[0028] The beneficial effects of this invention are:

[0029] 1. By constructing a rotor position harmonic dynamic suppression module, the rotor position signal harmonics generated by high-frequency signal injection and estimation are fully suppressed. A cyclic iterative strategy is used, and a forgetting factor is introduced to obtain the rotor position tracking error in real time and generate a compensation value.

[0030] 2. By constructing a rotor position error extraction module and a rotor position information calculation module, the extraction of rotor position information from high-frequency current signals is ensured, thereby improving the stability of the motor controller's control performance.

[0031] 3. The control variables are all simple and easy to measure, and the sensorless algorithm used by the controller can be implemented through software programming or model building without the need for additional hardware facilities, which reduces the cost of the controller, improves the performance and quality of the controller, and is conducive to engineering practice. Attached Figure Description

[0032] Figure 1 This is a structural block diagram of the permanent magnet hub motor system of the present invention;

[0033] Figure 2 This is a connection diagram of a sensorless control system for high-frequency harmonic suppression of a hub motor;

[0034] Figure 3 This is a block diagram of the rotor position error extraction module.

[0035] Figure 4 This is a block diagram of the rotor position information calculation module.

[0036] Figure 5 This is a block diagram of the rotor position harmonic dynamic suppression module.

[0037] Figure 1Among them, 11. PARK inverse converter module, 12. SVPWM modulation module, 13. three-phase inverter module, 14. permanent magnet hub motor, and 15. CLARK converter module;

[0038] Figure 2 The system consists of: 1. Permanent magnet hub motor system; 2. Rotor position error extraction module; 3. Rotor position information calculation module; 4. Rotor position harmonic dynamic suppression module; 5. Signal separation module; and 6. PARK conversion module. Detailed Implementation

[0039] The present invention will be further described below with reference to the accompanying drawings and embodiments. The drawings are simplified schematic diagrams, which only illustrate the basic structure of the present invention in a schematic manner, and therefore only show the components related to the present invention.

[0040] like Figure 1 As shown, the permanent magnet hub motor system 1 consists of a PARK inverter module 11, an SVPWM modulation module 12, a three-phase inverter module 13, a permanent magnet hub motor 14, and a CLARK converter module 15 connected in series; the permanent magnet hub motor system 1 uses a reference voltage with a high-frequency signal injected along the γδ reference axis. and rotor position estimate As input, with αβ axis current i α i β For output; the PARK inverse converter module 11, SVPWM module 12, and three-phase inverter module are connected in series, and the reference voltage for injecting high-frequency signals along the γδ reference axis. and rotor position estimate As the input to PARK inverse transformer module 11, the output αβ axis reference voltage is... This voltage serves as the input to the SVPWM modulation module 12, and the SVPWM modulation module 12 outputs a three-phase voltage u. abc This voltage serves as the input to the three-phase inverter module 13, and the three-phase inverter module 13 outputs a three-phase current i. abc This current serves as the input to the permanent magnet hub motor 14 and the CLARK converter module 15, and the CLARK converter module 15 outputs the αβ axis current i. α i β .

[0041] like Figure 2 The sensorless controller for the permanent magnet hub motor shown comprises a permanent magnet hub motor system 1, a rotor position error extraction module 2, a rotor position information calculation module 3, a rotor position harmonic dynamic suppression module 4, a signal separation module 5, and a PARK conversion module 6, forming a closed-loop sensorless controller. The αβ axis current i output by the permanent magnet hub motor system 1... α i βAfter passing through signal separation module 5, the high-frequency αβ axis current i is output. αh i βh and low-frequency αβ axis current signal i αl i βl αβ axis current i containing high-frequency signals αh i βh and rotor position estimate The input is fed to rotor position error extraction module 2 for error extraction to obtain rotor position error ε; while the low-frequency αβ shaft current signal i αl i βl The input is then given to PARK transformation module 6 to obtain the γδ reference axis current i. δ i γ Used for current closed-loop control.

[0042] like Figure 3 As shown, the rotor position error extraction module 2 consists of a PARK conversion module 21, a low-pass filter 22, and a per-unit conversion module 23. The PARK conversion module 21 uses the αβ axis current i of the high-frequency signal. αh i βh and rotor position estimate As input, the output γδ reference axis high-frequency current i γh i δh ,expression:

[0043]

[0044] Among them, i γh i δh For the high-frequency current of the γδ reference axis, i αh i βh For the αβ axis current.

[0045] i γh i δh The low-pass filter 22 filters the high-frequency signal in the current to obtain the low-frequency current i′. γh 、i′ δh The current signal is input to the per-unit module 23 for per-unit processing, and then the rotor position error ε is obtained, with the expression as follows:

[0046]

[0047] Where, i′ γh 、i′ δh It is a low-frequency current;

[0048] like Figure 4 As shown, the constructed rotor position information calculation module 3 uses the rotor position error ε and the high-frequency current error compensation value ΔI. cAs input, the two signals are summed and then passed through two adjustment modules. Finally, a low-pass filter module 31 is used to filter the high-frequency signal to obtain the speed estimate. Rotor position estimation value The rotor position information calculation module 3 obtains the rotor position information mainly based on the following expression by using an integral module to obtain the estimated rotational speed:

[0049]

[0050] In the formula, k p k i These are the gain values ​​of the adjustment module, typically ranging from 1 to 10, ε is the rotor position error, and ΔI is the gain value of the adjustment module. c This is the high-frequency current error compensation value. This is an estimated value for the rotational speed. This is the estimated rotor position.

[0051] like Figure 5 As shown, the rotor position harmonic dynamic suppression module 4 uses the speed reference value Speed ​​estimate Using the two signals as input, the difference is calculated to obtain the rotor speed estimation error. The rotor speed estimation error, after passing through the dynamic integration module 41 and the time-varying iterative gains Γ(t) and Φ(t), is compared with the high-frequency current error compensation value ΔI. c The feedback gain value is cyclically compensated, mainly based on the following expression:

[0052]

[0053] Among them, the time-varying iterative gains Γ(t), Φ(t), and ΔI c The initial value of (t) can be set to 0; the value of the forgetting factor λ can affect the effect of the time-varying iterative gain on the cyclic iteration suppression of rotor estimation error, so its value range is 0 to 1; X, as the standard for adjusting the iterative learning gain by comparing it with the average error evaluation function, can be set according to the rated speed, such as 1% of the rated speed of the motor. λ and X can be fine-tuned according to the requirements of the control system. p1 k i1 With k p2 k i2 These are the PI adjustment parameter values ​​for the time-varying iterative gain Γ(t) and Φ(t) functions, respectively, and their values ​​typically range from 1 to 10.

[0054] The permanent magnet hub motor system 1, rotor position error extraction module 2, rotor position information calculation module 3, and rotor position harmonic dynamic suppression module 4 are connected in series. A high-frequency voltage signal is injected into the γ-axis, and the feedback rotor error and γδ reference shaft current i are processed. δi γ The speed loop and current loop are constructed separately for PI regulation, thereby realizing sensorless control of the permanent magnet hub motor; the proposed rotor position error extraction module 2 and rotor position information calculation module 3 ensure the extraction and calculation of rotor position information, realizing basic sensorless control;

[0055] The rotor position harmonic dynamic suppression module 4 compensates for the error of the estimated rotor position by using a time-varying iterative gain function and feedback compensation with a forgetting factor. This enables iterative processing of harmonics and high-frequency signals present in the estimation error, further accurate calculation of rotor position information, and ensures the stability of the sensorless control performance of the hub motor.

[0056] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A sensorless control system for high-frequency harmonic suppression of hub motors, characterized in that, The permanent magnet hub motor system is composed of a permanent magnet hub motor system, a rotor position error extraction module, a rotor position information calculation module, a rotor position harmonic dynamic suppression module, a signal separation module, and a PARK conversion module connected in series. The output of the permanent magnet hub motor system is... shaft current , After passing through the signal separation module, the high frequency is output. shaft current , and low frequency shaft current signal , High-frequency signals shaft current , and rotor position estimate The input is fed into the rotor position error extraction module for error extraction to obtain the rotor position error. ; while low-frequency signals shaft current signal , Then the input is given to the PARK transformation module to obtain... Reference axis current , Used for current closed-loop control; The rotor position harmonic dynamic suppression module uses the speed reference value Speed ​​estimate Using the two signals as input, the difference is calculated to obtain the rotor speed estimation error. The rotor speed estimation error is processed by a dynamic integration module and a time-varying iterative gain. , Later, the high-frequency current error compensation value The feedback gain value is used for cyclic compensation, and the expression is: (4) in, , For time-varying iterative gain, This is the high-frequency current error compensation value; Forgetting factor; The average error evaluation function is... , and , These are for time-varying iterative gains , The PI adjustment parameter value of the function; Rotor position error and high-frequency current error compensation value The calculated estimated speed value and rotor position estimate .

2. The sensorless control system for high-frequency harmonic suppression of hub motors according to claim 1, characterized in that, The permanent magnet hub motor system consists of a PARK inverter module, an SVPWM modulation module, a three-phase inverter module, a permanent magnet hub motor, and a CLARK converter module connected in series. Reference voltage for injecting high-frequency signals into the reference axis , and rotor position estimate As the input to the PARK inverse transform module, the output is... Shaft reference voltage , This serves as the input to the SVPWM modulation module, which outputs a three-phase voltage. ; This serves as the input to the three-phase inverter module, which outputs three-phase current. ; It serves as the input to the permanent magnet hub motor and the CLARK converter module, and the CLARK converter module outputs... shaft current , .

3. The sensorless control system for high-frequency harmonic suppression of hub motors according to claim 1, characterized in that: The rotor position error extraction module consists of a PARK transform module, a first low-pass filter, and a per-unit module. The PARK transform module uses high-frequency signals... shaft current , and rotor position estimate As input, output Reference axis high frequency current , The expression is: (1) in, , for Reference axis high-frequency current, , for High-frequency signal of shaft current; , The high-frequency signal in the input current is filtered by the first low-pass filter to obtain the low-frequency current. , The current signal is then input to the per-unit module for per-unit processing to obtain the rotor position error. The expression is: (2) in, , It is a low-frequency current.

4. The sensorless control system for high-frequency harmonic suppression of hub motors according to claim 1, characterized in that: The rotor position information calculation module uses rotor position error and high-frequency current error compensation value As input, the two signals are summed and then passed through two adjustment modules. Finally, a second low-pass filter module is used to filter the high-frequency signal, thereby obtaining the speed estimate. The rotor position estimate The result is obtained by using an integral module on the outputs of the two adjustment modules, expressed as: (3) in, , These are the gain values ​​of the adjustment module. For rotor position error, This is the high-frequency current error compensation value. This is an estimated value for the rotational speed. This is the estimated rotor position.

5. A method for a sensorless control system for high-frequency harmonic suppression of a hub motor as described in any one of claims 1-4, characterized in that, Includes the following steps: Step 1: Inject high-frequency signal The reference shaft voltage is input to the permanent magnet hub motor system, and the output is... shaft current , ; Step 2, shaft current , The input is fed into the signal separation module to obtain high frequency signals. shaft current , and low frequency shaft current signal , ; Step 3: Convert the high-frequency signal shaft current , and rotor position estimate The rotor position error is input into the rotor position error extraction module to obtain the rotor position error. ; Step 4: Adjust rotor position error and the high-frequency current error compensation value output by the rotor position harmonic dynamic suppression module. The accumulated values ​​are then input into the rotor position information calculation module to obtain the rotor position estimate. Speed ​​estimate ; Step 5: Set the speed reference value Speed ​​estimate The input is fed into the rotor position harmonic dynamic suppression module to obtain the high-frequency current error compensation value. This leads to the cyclical iterative suppression and compensation of rotor position estimation error.

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