Permanent magnet synchronous motor sensorless control method based on self-adaptive high-frequency signal injection

Abstract

The invention provides a permanent magnet synchronous motor sensorless control method based on self-adaptive high-frequency signal injection, and the method comprises the steps: carrying out the online calculation of the amplitude of an optimal high-frequency injection signal through building a relation model of the amplitude of a pulsating square wave high-frequency voltage signal, the total harmonic distortion rate of motor current, and the fundamental current; generating a pulsating square wave high-frequency voltage signal with the optimal amplitude; a current envelope containing rotor position information is extracted from high-frequency response current through a high-pass filtering and synchronous demodulation technology, and rotor position and rotating speed information is extracted by adopting a phase-locked loop structure and fed back to a closed-loop control system. According to the method, the current harmonic content is strictly limited within the preset range by dynamically adjusting the amplitude of the injection signal, high-frequency noise caused by a traditional fixed amplitude injection method is reduced, quick response and robustness of a system during load sudden change are ensured, and the contradiction that noise and precision are irreconcilable in a traditional method is effectively solved.

Description

Technical Field

[0001] This invention belongs to the field of sensorless control technology for permanent magnet synchronous motors, and relates to a sensorless control method for permanent magnet synchronous motors based on adaptive high-frequency signal injection. Background Technology

[0002] With their high efficiency, high power density, excellent dynamic response, and good torque control performance, permanent magnet synchronous motors (PMSMs) are widely used in industrial automation, electric vehicles, aerospace, and robot servo systems. However, traditional PMSM control methods typically rely on position sensors (such as photoelectric encoders and resolvers) to obtain rotor position information in order to achieve precise field-oriented control (FOC) or direct torque control (DTC). While these sensors can provide high-precision position feedback, they also introduce several problems:

[0003] 1. Higher cost: The high price of high-precision encoders or rotary transformers increases the overall cost of the motor drive system, especially in large-scale industrial applications or consumer products where cost control is particularly important.

[0004] 2. Low reliability: Mechanical sensors are susceptible to environmental factors such as vibration, dust, and temperature changes. Long-term operation may lead to signal drift, poor contact, or even failure, affecting the stability and lifespan of the system.

[0005] 3. High complexity: The installation of sensors requires additional mechanical structure design and must consider the anti-interference problem of signal transmission, which increases the design difficulty and maintenance cost of the system.

[0006] To overcome the aforementioned problems and eliminate reliance on sensors, sensorless control technology has emerged. This technology estimates rotor position using the motor's own electrical characteristics (such as back electromotive force), thereby eliminating the need for mechanical sensors, improving system reliability, and reducing costs. Currently, sensorless control methods are mainly classified into the following categories:

[0007] 1. Methods based on back electromotive force (Back-EMF):

[0008] Suitable for medium to high-speed operation, such as sliding mode observers (SMO) and extended Kalman filters (EKF). Disadvantage: At low or zero speeds, the back electromotive force amplitude is too low, leading to decreased estimation accuracy or even failure.

[0009] 2. Methods based on High-Frequency Signal Injection (HFSI):

[0010] By injecting high-frequency voltage or current signals into the motor, rotor position information can be extracted using the motor's saliency effect or magnetic saturation effect. This method is suitable for low-speed or even zero-speed operation, and common methods include high-frequency sine wave injection and high-frequency square wave injection. However, traditional high-frequency signal injection methods (such as fixed-amplitude square wave or sine wave injection) can lead to excessively high total harmonic content of the current, generating sharp high-frequency noise and affecting the acoustic performance of the motor.

[0011] 3. Artificial intelligence (AI) based methods:

[0012] In recent years, AI technologies such as deep learning and neural networks have been introduced into sensorless control to improve the robustness of position estimation. Disadvantages include high computational complexity and stringent real-time requirements; currently, it remains primarily in the research stage and has not yet been widely applied.

[0013] While existing high-frequency signal injection methods have achieved rotor position estimation at zero and low speeds in sensorless control, they still have significant limitations in practical applications. First, traditional methods typically use fixed-amplitude high-frequency voltage signals (such as sine or square waves) for injection, resulting in high total harmonic distortion (THD) and consequently sharp high-frequency noise, severely impacting the motor's acoustic performance and system stability. Second, fixed-amplitude injection methods cannot dynamically adapt to load changes: when the motor load suddenly increases, if the injected signal amplitude... If the current is too low, the high-frequency response current will decay rapidly, leading to a decrease in position estimation accuracy or even failure; while if... While excessively high values ​​can improve the signal-to-noise ratio, they can further exacerbate current harmonics and noise problems, creating an irreconcilable contradiction.

[0014] Furthermore, existing methods lack [further details needed]. The system's active control capability limits it to a static trade-off between noise and accuracy, preventing real-time optimization based on operating conditions. For example, under light load or steady-state operation, a fixed... This may introduce unnecessary harmonic interference; and under heavy load or dynamic conditions, insufficient amplitude may affect control performance. This rigid design not only limits the system's adaptability but also increases the difficulty of debugging, making it difficult to balance parameters in engineering applications and meet the requirements of high efficiency, low noise, and high precision operation.

[0015] In summary, the problems with existing technologies include:

[0016] 1. Noise and accuracy are incompatible: the amplitude is fixed and cannot be dynamically balanced. With estimation accuracy.

[0017] 2. Poor load adaptability: When the load changes abruptly, the fixed load... This may lead to insufficient high-frequency current response and inaccurate position estimation.

[0018] Therefore, there is an urgent need for a method that can dynamically adjust the high-frequency injection signal and simultaneously optimize... A new control strategy for estimating accuracy. Summary of the Invention

[0019] This invention provides a sensorless control method for permanent magnet synchronous motors based on adaptive high-frequency signal injection. It is a dynamically optimized high-frequency signal injection method that establishes the harmonic content (…). ), Axial base wave current ( ) and injection amplitude ( The physical relationship model is designed to improve some problems in sensorless control of permanent magnet synchronous motors based on high-frequency signal injection, as follows:

[0020] Configure as needed The parameters control the current harmonic content within a certain range, thereby reducing the sharp noise caused by high-frequency signal injection and improving acoustic performance; while ensuring motor noise, the rotor position estimation accuracy is maximized, improving the dynamic performance and stability of the system.

[0021] The technical solution of this invention is as follows:

[0022] A sensorless control method for a permanent magnet synchronous motor based on adaptive high-frequency signal injection, the method comprising:

[0023] Step 1: Establish the amplitude of the pulsed square wave high-frequency voltage injection signal and A physical model of the relationship between the fundamental frequency current and the total harmonic distortion (THD) was developed, and the specific relationship between the three variables was fitted by collecting data.

[0024] Step Two: Using the fitting relationship, based on the collected data... Shaft fundamental frequency current, set Calculate the optimal amplitude of the high-frequency voltage injection signal and generate a pulsed square wave high-frequency voltage injection signal with the optimal amplitude.

[0025] Step 3: Inject the pulsed square wave high-frequency voltage injection signal into the permanent magnet synchronous motor in the low-speed range of the motor's operation, and extract the current response signal.

[0026] Step 4: Perform high-pass filtering on the extracted current, and use the demodulated signal to extract the high-frequency response current envelope containing rotor position information from the filtered high-frequency response current. The demodulated signal is obtained by delaying the high-frequency square wave voltage injection signal by one sampling period.

[0027] Step 5: Use a phase-locked loop structure to extract rotor position and speed information from the high-frequency response current envelope, and use the extracted information as a feedback signal to perform closed-loop control of the permanent magnet synchronous motor without sensors.

[0028] A computing device includes: at least one processor and a memory storing program instructions; when the program instructions are read and executed by the processor, the computing device causes the computing device to perform a sensorless control method for a permanent magnet synchronous motor based on adaptive high-frequency signal injection.

[0029] A readable storage medium storing program instructions, which, when read and executed by a computing device, cause the computing device to perform a sensorless control method for a permanent magnet synchronous motor based on adaptive high-frequency signal injection.

[0030] A computer program product includes a computer program that, when executed by a processor, implements a sensorless control method for a permanent magnet synchronous motor based on adaptive high-frequency signal injection.

[0031] Beneficial effects:

[0032] 1. Online real-time control Based on harmonic content and fundamental current Feedback to dynamically adjust the amplitude of the injected signal ,make sure Always limited to a set threshold;

[0033] 2. Maximize estimation accuracy: In Adaptive boosting under constraints To reach the critical value, in order to optimize the signal-to-noise ratio (SNR);

[0034] 3. Noise and performance synergistic optimization: Breaking through the static limitations of the traditional fixed amplitude method, it achieves low noise and high precision control under all operating conditions. Attached Figure Description

[0035] Figure 1 This is a flowchart of the sensorless control method for permanent magnet synchronous motors based on adaptive adjustment of the amplitude of high-frequency square wave injection signal according to the present invention;

[0036] Figure 2 This is a structural block diagram of the overall control system of the present invention;

[0037] Figure 3This is a block diagram of a phase-locked loop (PLL). Detailed Implementation

[0038] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the disclosure to those skilled in the art. It should be noted that, unless otherwise specified, embodiments and features described herein can be combined with each other.

[0039] This invention proposes a sensorless control method for permanent magnet synchronous motors based on adaptive high-frequency signal injection, which can improve the problems of high noise and estimation accuracy of permanent magnet synchronous motors under high-frequency signal injection. Figure 1 A schematic flowchart of the method is shown. (e.g.) Figure 1 As shown, the method includes:

[0040] Step 1: Establish the amplitude of the pulsed square wave high-frequency voltage injection signal and Shaft fundamental frequency current, total harmonic distortion (THD) The physical model between the three variables was constructed, and the specific relationship between the three variables was fitted by collecting data.

[0041] Specifically, in step one:

[0042] Based on the estimated high-frequency current response of the permanent magnet synchronous motor in the stationary coordinate system under pulsed square wave high-frequency voltage injection in the rotating coordinate system, the following is given:

[0043] (1)

[0044] In the formula, These represent the high-frequency components of the current in the stationary coordinate system after filtering and demodulation, respectively. for Shaft inductance component; Indicates the frequency of the injected high-frequency voltage signal; This indicates the amplitude of the injected high-frequency square wave voltage; This represents the actual rotor position of the permanent magnet synchronous motor.

[0045] Write the fundamental current equation, high-frequency current response equation, and total harmonic distortion rate expression for the permanent magnet synchronous motor:

[0046] (2)

[0047] in, These represent the fundamental frequency components of the current in the rotating coordinate system; The total harmonic distortion of the current. These represent the base frequency current and high frequency current of the permanent magnet synchronous motor, respectively. Representing electric current Second harmonic components.

[0048] calculate The effective value of the current needs to be used, and the result calculated by equation (2) is... Since the value is the amplitude, we can transform the above equation to obtain:

[0049] (3)

[0050] In a sensorless control system for a permanent magnet synchronous motor based on high-frequency signal injection, current harmonics are mainly caused by factors such as high-frequency response, inverter nonlinearity, and motor asymmetry. Among these, the high-frequency current response is dominant, and the harmonic components generated by other factors can be considered as minimal disturbances, approximating as constants. Therefore, the above equation can be transformed into:

[0051] (4)

[0052] Where, constant ,constant , This is for error compensation.

[0053] By collecting data from simulations and experiments By fitting the data, we can deduce... The accurate value is obtained, and thus the accurate relational expression is derived.

[0054] Step Two: Using the fitting relationship, based on the collected data... Shaft fundamental frequency current, set The optimal amplitude of the high-frequency injection signal is calculated, and a pulsed square wave high-frequency voltage injection signal with the optimal amplitude is generated.

[0055] Specifically, step two includes: utilizing the collected data in simulations or experiments. Shaft fundamental frequency current and setting The optimal amplitude of the high-frequency square wave injection signal is calculated, and a high-frequency square wave signal with the optimal amplitude is generated.

[0056] Set according to actual needs The values ​​are used to limit the total harmonic distortion (THD) and high-frequency noise of the permanent magnet synchronous motor (PMSM) within the required range; the current of the PMSM is sampled and its coordinates are transformed to obtain its... The shaft current is then low-pass filtered to obtain the fundamental frequency current. The obtained and Substituting the values ​​into the fitted equation (4), we can derive the equation that satisfies... Maximum required high-frequency square wave voltage signal amplitude .

[0057] Within a reasonable range, when the frequency of the injected high-frequency square wave voltage signal is constant, increasing the injection amplitude of the high-frequency square wave can improve the signal-to-noise ratio and reduce the position estimation error. Therefore, choosing... The amplitude of the high-frequency square wave injection signal can satisfy... Minimize position and velocity estimation errors while meeting requirements.

[0058] Step 3: Inject the high-frequency voltage injection signal into the permanent magnet synchronous motor during the low-speed range of its operation, and extract the current response signal.

[0059] Specifically, step three:

[0060] A high-frequency voltage injection signal is injected into the estimated rotating coordinate system.

[0061] The high-frequency voltage injection signal is represented in the estimated rotating coordinate system as follows:

[0062] (5)

[0063] in, Indicates a high-frequency injection signal. Estimation of rotating coordinate system for high-frequency voltage injection signal Axial voltage component, unit square wave function , For runtime, The sampling period is for Divide by The remaining items.

[0064] Step 4: Perform high-pass filtering on the extracted current, and use the demodulated signal to extract the high-frequency response current envelope containing rotor position information from the filtered high-frequency response current. The demodulated signal is obtained by delaying the high-frequency square wave voltage injection signal by one sampling period.

[0065] Specifically, in step four:

[0066] By sampling the phase current of the permanent magnet synchronous motor and transforming it from a three-phase coordinate system to a stationary coordinate system, the current in the two-phase stationary coordinate system is obtained. ,make The high-frequency response current envelope is extracted using a high-pass filter. Demodulate.

[0067] The high-frequency response current is represented in the stationary coordinate system as:

[0068] (6)

[0069] in, For differential operators, The high-frequency component of the current in a stationary coordinate system. This represents the actual rotor position. For the actual rotor position and the estimated rotor position angular difference, They represent Shaft inductance component;

[0070] Injecting high-frequency voltage into the signal Substituting into equation (6), when the estimated position is the actual position, i.e., the angle difference... When it is zero, there is and Therefore:

[0071] (7)

[0072] Multiplying the extracted high-frequency current signal by a unit high-frequency voltage injection signal delayed by one sampling period yields the demodulated high-frequency current response:

[0073] (8)

[0074] in, This represents the demodulated signal obtained by delaying the high-frequency voltage injection signal by one sampling period. It is evident that this high-frequency current response contains rotor position information.

[0075] Step 5: Use a phase-locked loop structure to extract rotor position and speed information from the high-frequency response current envelope, and use the extracted information as a feedback signal to perform closed-loop control of the permanent magnet synchronous motor without sensors.

[0076] Specifically, in step five:

[0077] Figure 3 This is a block diagram of a phase-locked loop (PLL). The PLL structure mainly includes a proportional-integral (PI) controller and an integral element. Figure 3 In this context, PI stands for Proportional Integral Controller. For the points-based process, Indicates the estimated electric angular velocity, This represents the number of pole pairs of the motor. It is estimated location information. This is the estimated rotational speed. The demodulated high-frequency current response signal... enter Figure 3The phase-locked loop structure shown can be used to estimate the rotor position and speed.

[0078] In this embodiment, the injection signal for the permanent magnet motor is obtained by calculating the amplitude of a high-frequency square wave voltage signal. This method improves upon existing fixed-amplitude square wave signal injection methods, thereby reducing current harmonic content and keeping it within a set range, thus achieving noise suppression. While meeting conditions such as harmonic content, it can select the maximum injection signal amplitude, ensuring high position and speed observation accuracy in motor control, stable system operation, and good dynamic performance.

[0079] Figure 2 This is a structural block diagram of an example overall control system of the present invention, used to illustrate the complete sensorless control process from injection signal amplitude calculation, coordinate transformation, current sampling, high-pass filtering to signal demodulation and phase-locked loop observation. The following is in conjunction with... Figure 2 The following is a detailed description of the entire control process of the permanent magnet synchronous motor of the present invention:

[0080] Figure 2 The system mainly consists of four parts: amplitude calculation, signal processing, observer, and control system.

[0081] First, set the maximum permissible total harmonic distortion rate based on actual needs. Using relational expressions (in (All are constants), obtained through data collection Shaft fundamental frequency current Derive the optimal (maximum) high-frequency square wave signal amplitude. And generate the corresponding high-frequency square wave injection signal. Using the reference speed With feedback speed The difference is used to obtain the reference current through a proportional-integral (PI) controller. Next, through the reference current ( ) and the low-frequency component of the feedback current ( The difference is used to obtain the current error, which is then input into the current regulator to obtain the voltage required for motor vector control. and and the square wave voltage generated by the high-frequency square wave signal generator. The final voltage signal injected into the motor is obtained by superimposing these signals. This is then compared with the estimated position information. The combined action performs a coordinate transformation to obtain a given voltage signal in the stationary coordinate system. This signal is converted into a Space Vector Pulse Width Modulation (SVPWM) voltage signal and input into the motor for control. Then, the motor current is sampled to obtain the three-phase AC current. The current in the stationary coordinate system is obtained by performing a stationary coordinate transformation (Clark transformation). This includes a random high-frequency response current component and a low-frequency component used for vector control. Therefore, a low-pass filter (LPF) is added to the current feedback path to extract the low-frequency component of the current. The low-frequency component of the feedback current is obtained by combining it with the estimated location. To obtain location information, it is necessary to combine it with a sampling period that has been delayed ( The demodulated signal output from the high-frequency square wave signal generator is filtered by a high-pass filter (HPF) to obtain the current. Signal processing is performed to obtain the envelope signal of the high-frequency response current that includes the location. The estimated position is obtained by inputting the data into the phase-locked loop observer. Compared with the estimated speed .

[0082] The present invention also provides a computing device, comprising: at least one processor and a memory storing program instructions; when the program instructions are read and executed by the processor, the computing device causes the computing device to perform a sensorless control method for a permanent magnet synchronous motor based on adaptive high-frequency signal injection.

[0083] The present invention also provides a readable storage medium storing program instructions, which, when read and executed by a computing device, cause the computing device to perform a sensorless control method for a permanent magnet synchronous motor based on adaptive high-frequency signal injection.

[0084] The present invention also provides a computer program product, including a computer program that, when executed by a processor, implements a sensorless control method for a permanent magnet synchronous motor based on adaptive high-frequency signal injection.

[0085] The above embodiments are only used to illustrate the design concept and features of the present invention, and their purpose is to enable those skilled in the art to understand the content of the present invention and implement it accordingly. Therefore, all equivalent changes or modifications made based on the principles and design ideas disclosed in the present invention are within the protection scope of the present invention.

Claims

1. A sensorless control method for a permanent magnet synchronous motor based on adaptive high-frequency signal injection, characterized in that, The method includes: Step 1: Establish the amplitude of the pulsed square wave high-frequency voltage injection signal and Shaft fundamental frequency current, total harmonic distortion The physical model between the three variables was constructed, and the specific relationship between the three variables was fitted by collecting data. Step Two: Using the fitting relationship, based on the collected data... Shaft fundamental frequency current, set Calculate the optimal amplitude of the high-frequency voltage injection signal and generate a pulsed square wave high-frequency voltage injection signal with the optimal amplitude. Step 3: Inject the pulsed square wave high-frequency voltage injection signal into the permanent magnet synchronous motor in the low-speed range of the motor's operation, and extract the current response signal. Step 4: Perform high-pass filtering on the extracted current, and use the demodulated signal to extract the high-frequency response current envelope containing rotor position information from the filtered high-frequency response current. The demodulated signal is obtained by delaying the high-frequency square wave voltage injection signal by one sampling period. Step 5: Use a phase-locked loop structure to extract rotor position and speed information from the high-frequency response current envelope, and use the extracted information as a feedback signal to perform closed-loop control of the permanent magnet synchronous motor without sensors.

2. The sensorless control method for permanent magnet synchronous motors based on adaptive high-frequency signal injection according to claim 1, characterized in that, In step one, the high-frequency current response of the permanent magnet synchronous motor in the stationary coordinate system based on the estimated high-frequency voltage injection of the pulsating square wave in the rotating coordinate system is: （1） In the formula, These represent the high-frequency components of the current in the stationary coordinate system after filtering and demodulation, respectively. for Shaft inductance component; Indicates the frequency of the injected high-frequency voltage signal; This indicates the amplitude of the injected high-frequency square wave voltage; This represents the actual rotor position of the permanent magnet synchronous motor. Write the fundamental current equation, high-frequency current response equation, and total harmonic distortion rate expression for the permanent magnet synchronous motor: （2） in, These represent the fundamental frequency components of the current in the rotating coordinate system; The total harmonic distortion of the current. These represent the base frequency current and high frequency current of the permanent magnet synchronous motor, respectively. Representing electric current Second harmonic components; Further written as: （4） Where, constant ,constant , This is for error compensation.

3. The sensorless control method for permanent magnet synchronous motors based on adaptive high-frequency signal injection according to claim 2, characterized in that, Step two includes: Set according to actual needs The values ​​are used to limit the total harmonic distortion (THD) and high-frequency noise of the permanent magnet synchronous motor (PMSM) within the required range; the current of the PMSM is sampled and its coordinates are transformed to obtain its... The shaft current is then low-pass filtered to obtain the fundamental frequency current. The obtained and Substituting the values ​​into the fitted equation (4), we can derive the equation that satisfies the following online: Maximum required high-frequency square wave voltage signal amplitude .

4. The sensorless control method for permanent magnet synchronous motors based on adaptive high-frequency signal injection according to claim 3, characterized in that, Step three includes: injecting a high-frequency voltage injection signal into the estimated rotating coordinate system, wherein the high-frequency voltage injection signal is represented in the estimated rotating coordinate system as follows: （5） in, Indicates a high-frequency injection signal. Estimation of rotating coordinate system for high-frequency voltage injection signal Axial voltage component, unit square wave function , For runtime, The sampling period is for Divide by The remaining items.

5. The sensorless control method for permanent magnet synchronous motors based on adaptive high-frequency signal injection according to claim 4, characterized in that, Step four includes: sampling the phase current of the permanent magnet synchronous motor and transforming it from a three-phase coordinate system to a stationary coordinate system to obtain the current in a two-phase stationary coordinate system. ,make The high-frequency response current envelope is extracted using a high-pass filter. Demodulate.

6. The sensorless control method for permanent magnet synchronous motors based on adaptive high-frequency signal injection according to claim 5, characterized in that, In step four, the high-frequency response current is represented in the stationary coordinate system as follows: （6） in, For differential operators, The high-frequency component of the current in a stationary coordinate system. This represents the actual rotor position. For the actual rotor position and the estimated rotor position angular difference, They represent Shaft inductance component; Injecting high-frequency voltage into the signal Substituting into equation (6), when the estimated position is the actual position, i.e., the angle difference... When it is zero, there is and ,therefore: （7） The extracted high-frequency current signal is multiplied by a unit high-frequency voltage injection signal delayed by one sampling period to obtain the demodulated high-frequency current response: （8） in, This represents the demodulated signal obtained by delaying the high-frequency voltage injection signal by one sampling period.

7. The sensorless control method for permanent magnet synchronous motors based on adaptive high-frequency signal injection according to claim 6, characterized in that, In step five: the phase-locked loop structure includes a proportional-integral controller (PI) and an integral element.

8. A computing device, characterized in that, include: At least one processor and a memory storing program instructions; When the program instructions are read and executed by the processor, the computing device performs the sensorless control method for permanent magnet synchronous motors based on adaptive high-frequency signal injection as described in any one of claims 1-7.

9. A readable storage medium storing program instructions, characterized in that, When the program instructions are read and executed by the computing device, the computing device performs the sensorless control method for permanent magnet synchronous motors based on adaptive high-frequency signal injection as described in any one of claims 1-7.

10. A computer program product, comprising a computer program, characterized in that, When the computer program is executed by the processor, it implements the sensorless control method for permanent magnet synchronous motors based on adaptive high-frequency signal injection as described in any one of claims 1-7.

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