A low-speed position sensorless control method for a dual three-phase permanent magnet synchronous motor

Abstract

This invention relates to the field of permanent magnet synchronous motor control technology and provides a low-speed sensorless control method for dual three-phase permanent magnet synchronous motors. The method includes: Step 1, establishing a high-frequency voltage model considering coupled inductance and its asymmetry under the observation shaft system; Step 2, designing an alternating high-frequency square wave voltage injection method for the dual observation shaft system, utilizing the difference in self-inductance and mutual inductance effects between windings to achieve half-wave antisymmetry of the bias disturbance signal; Step 3, extracting a current component at one injection frequency based on amplitude-frequency analysis results to reconstruct the position tracking deviation signal, eliminating the bias disturbance; Step 4, inputting the reconstructed position tracking deviation signal into a phase-locked loop to obtain the rotor position and speed. This method eliminates the bias disturbance in the position tracking deviation signal, improving the position observation accuracy and system stability under heavy load conditions.

Description

Technical Field

[0001] This invention belongs to the field of permanent magnet synchronous motor control technology, and particularly relates to a low-speed sensorless control method for dual three-phase permanent magnet synchronous motors. Background Technology

[0002] Permanent magnet synchronous motors (PMSMs) are widely used in home appliances and electric vehicles due to their high power density and efficiency. Among them, the dual three-phase PMSM, as a typical topology in multi-phase PMSM systems, exhibits lower torque ripple and stronger fault tolerance, showing significant application prospects in aerospace, wind power generation, and marine transportation. For achieving high-performance drive of the motor system, obtaining accurate rotor position is crucial; therefore, encoders are an important component of the motor drive control system. However, under extreme operating conditions, encoder reliability becomes a significant factor affecting system stability. To improve the reliability of the motor drive system under harsh conditions, sensorless control technology can be employed. This technology uses algorithms to estimate rotor position, thereby replacing traditional mechanical position sensors.

[0003] When a motor operates in the zero-speed range, high-frequency voltage injection is typically used to achieve sensorless control. This method utilizes the salient pole effect of the motor to observe the rotor position. However, as the motor load increases and magnetic saturation strengthens, coupling inductance exists between the motor's dq shaft system. This leads to an error between the observed rotor position obtained based on high-frequency voltage injection and the actual position. If the position observation error is too large, the sensorless control system will become unstable. Compared to traditional single-phase three-phase permanent magnet synchronous motors, the coupling inductance relationship between the dq shaft systems of dual-phase three-phase permanent magnet synchronous motors is more complex, including coupling inductance between dq shaft systems with the same winding and coupling inductance between dq shaft systems with different windings. Due to differences in the coupling magnetic circuit and manufacturing tolerances, an inherent asymmetry exists between these two types of coupling inductance. When using traditional single-shaft high-frequency voltage injection in dual-phase three-phase permanent magnet synchronous motors, this coupling inductance asymmetry will affect the position tracking deviation signal. Introducing bias perturbation signal This significantly reduces the accuracy of position observation, and large position observation errors can affect the control performance of sensorless systems, even causing instability in the control system. Therefore, it is of great significance to study a low-speed sensorless control method for dual three-phase permanent magnet synchronous motors with high position observation accuracy. Summary of the Invention

[0004] The purpose of this invention is to provide a low-speed sensorless control method for dual three-phase permanent magnet synchronous motors, aiming to solve the problems mentioned in the background art.

[0005] The present invention is implemented as follows: a low-speed sensorless control method for a dual three-phase permanent magnet synchronous motor includes the following steps: Step 1: Establish a high-frequency voltage model of a dual three-phase permanent magnet synchronous motor considering the coupled inductance and its asymmetry under the observation axis; Step 2: Design a dual-observation-axis alternating high-frequency square wave voltage signal injection method, and use the difference between the self-inductance and mutual inductance effects between windings to achieve half-wave antisymmetry of the bias disturbance signal caused by the asymmetry of the coupled inductance within the high-frequency injection cycle; Step 3: Based on the amplitude-frequency analytical calculation results of the components of the high-frequency current in a single-axis system, a bandpass filter is used to extract the current component with a higher signal-to-noise ratio at the injection frequency from the high-frequency current for position tracking deviation signal reconstruction, thereby eliminating the bias disturbance in the original position tracking deviation signal. Step 4: Input the reconstructed position tracking deviation signal into a proportional-integral phase-locked loop to obtain the rotor position and speed, thereby ultimately achieving sensorless control and improving position observation accuracy.

[0006] A further technical solution is that, in step 1, the high-frequency voltage model considering the coupled inductance and its asymmetry under the observation axis is as follows: ; In the formula, For the high-frequency voltage vector of the γ1-δ1 axis system, For the high-frequency voltage vector of the γ2-δ2 axis system, For the high-frequency current vector of the γ1-δ1 axis system, For the high-frequency current vector of the γ2-δ2 axis system, For differential operators, This represents the position estimation error; Let dq be the self-inductance matrix of the axis system; Let dq be the mutual inductance matrix of the axis system; The four-dimensional coordinate transformation matrix is ​​represented as follows: ; ; ; ; In the formula, For the γ1 axis high-frequency voltage; For the γ2 axis high-frequency voltage; For the high-frequency current of the γ1 axis; For high-frequency current in the γ2 axis system; , , and These are the self-inductance and mutual inductance of the dq axis system, where... , , Leakage; This is a coupling inductance between the dq axis and the same winding. The ratio of the coupling inductance between the dq axis systems of the same winding to the coupling inductance between the dq axis systems of different windings indicates an inherent asymmetry in the coupling inductance between the windings of a dual three-phase permanent magnet synchronous motor. ; It is a two-dimensional coordinate transformation matrix; It is a zero matrix.

[0007] A further technical solution is that, in step 2, the high-frequency square wave voltage signal injected under the dual observation axis system is: ; In the formula, This represents the amplitude of a high-frequency square wave voltage. The period of a high-frequency square wave voltage; For a unit amplitude period signal, it is represented as: ; for Delay Periodic signals after a certain time; Substituting the expression for the alternating high-frequency square wave voltage injected under dual observation axes into the high-frequency voltage equation, we can solve for... High-frequency current in shaft system The expression is: ; In the formula, It serves as a high-frequency response current reference; Mainly coupled inductor; It is a secondary coupled inductor; It is a common-mode inductor; For differential inductors, these parameters are expressed as follows: ; ; Defined as bias perturbation signal It is caused by the asymmetry of the coupled inductance and is expressed as .

[0008] A further technical solution is that, in step 3, the high-frequency current... From DC component Odd harmonic components Even frequency components The composition, calculated through amplitude-frequency analysis, is as follows: ; ; In the formula, For component order; The angular frequency of the injected high-frequency signal; and They are respectively in Shaft system and When the shaft system is subjected to high-frequency voltage injection The response amplitudes are expressed as follows: ; In the formula, for The amplitude.

[0009] A further technical solution involves using a bandpass filter to extract the high-frequency current in step 4. One-time injection frequency component Its expression is: ; Will Shaft system next injection frequency component and Shaft system next injection frequency component Transform to a measuring axis system that is 45° out of phase to obtain the measuring axis system. The expression for high-frequency current in the shaft system is: ; The reconstructed position tracking deviation signal Represented as: ; In the formula, and High frequency current and The amplitude; Will Inputting the information into a proportional-integral phase-locked loop (PLL) enables the observation of rotor position and speed, thereby improving the accuracy of position observation.

[0010] This invention provides a low-speed sensorless control method for a dual three-phase permanent magnet synchronous motor. The method establishes a high-frequency voltage model of the motor considering coupled inductance and its asymmetry in the observation shaft system. It designs an alternating high-frequency square wave voltage injection method in the dual observation shaft system, utilizing the difference between self-inductance and mutual inductance effects between windings to achieve half-wave antisymmetry of the bias disturbance signal caused by coupled inductance asymmetry. Based on the spectral analysis calculation results of the high-frequency current, a component of one injection frequency is extracted from the high-frequency current using a bandpass filter, and this component is used to reconstruct the position tracking deviation signal to eliminate the bias disturbance signal. Finally, the reconstructed position tracking deviation signal is used to achieve position and speed observation. The proposed method eliminates the bias disturbance caused by coupled inductance asymmetry in the position tracking deviation signal, improves the position observation accuracy under heavy load conditions, and thus enhances the stability and load-carrying capacity of the sensorless control system. Attached Figure Description

[0011] Figure 1 This is an overall control block diagram of a low-speed sensorless control method for a dual three-phase permanent magnet synchronous motor provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of a reference coordinate system (where the subscripts "1" and "2" represent the first and second sets of windings, respectively, and the coordinate system includes...). Shaft system Shaft system Shaft system and Shaft systems, respectively representing stationary shaft systems, rotating shaft systems, observation shaft systems, and measurement shaft systems. Figure 3 To reconstruct the position tracking deviation signal structure block diagram; Figure 4 The experimental waveforms are shown for the motor operating at 150 r / min and 62.5% of rated load using the traditional single-shaft high-frequency voltage injection method. Figure 5 The experimental waveforms are shown when the motor is running at 150 r / min under rated load using this method. Detailed Implementation

[0012] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0013] The specific implementation of the present invention will be described in detail below with reference to specific embodiments.

[0014] like Figures 1-3 As shown, an embodiment of the present invention provides a low-speed sensorless control method for a dual three-phase permanent magnet synchronous motor, comprising the following steps: Step 1: Establish a high-frequency voltage model of a dual three-phase permanent magnet synchronous motor considering the coupled inductance and its asymmetry under the observation axis; Figure 1 The main components include dual-dq axis closed-loop vector control, dual-axis alternating high-frequency square wave voltage injection, response current extraction, position tracking deviation signal reconstruction module, and phase-locked loop (PLL). First, high-frequency square wave voltage signals are alternately injected into the dual observation axes of the system. Next, the current response signal is extracted and input to the position tracking deviation signal reconstruction module. Finally, the obtained position tracking deviation signal is input to the PLL to complete the observation of rotor position and speed. The high-frequency voltage model considering the coupled inductance and its asymmetry in the observation axis is as follows: ; In the formula, For the high-frequency voltage vector of the γ1-δ1 axis system, For the high-frequency voltage vector of the γ2-δ2 axis system, For the high-frequency current vector of the γ1-δ1 axis system, For the high-frequency current vector of the γ2-δ2 axis system, For differential operators, This represents the position estimation error; Let dq be the self-inductance matrix of the axis system; Let dq be the mutual inductance matrix of the axis system; The four-dimensional coordinate transformation matrix can be represented as follows: ; ; ; ; In the formula, For the γ1 axis high-frequency voltage; For the γ2 axis high-frequency voltage; For the high-frequency current of the γ1 axis; For high-frequency current in the γ2 axis system; , , and These are the self-inductance and mutual inductance of the dq axis system, where... , , Leakage; This is a coupling inductance between the dq axis and the same winding. The ratio of the coupling inductance between the dq axis systems of the same winding to the coupling inductance between the dq axis systems of different windings is given. Due to differences in the coupling magnetic circuit and manufacturing tolerances, the coupling inductance between the windings of a dual three-phase permanent magnet synchronous motor exhibits an inherent asymmetry. ; It is a two-dimensional coordinate transformation matrix; It is a zero matrix; Step 2: Design a dual-observation-axis alternating high-frequency square wave voltage signal injection method, which utilizes the difference between the self-inductance and mutual inductance effects between windings to achieve half-wave antisymmetry of the bias disturbance signal caused by the asymmetry of the coupled inductance within the high-frequency injection cycle.

[0015] The high-frequency square wave voltage signal injected under dual observation axes is: ; In the formula, This represents the amplitude of a high-frequency square wave voltage. The period of a high-frequency square wave voltage; For a unit amplitude period signal, it can be represented as: ; for Delay The periodic signal after time. Substituting the expression for the alternating high-frequency square wave voltage injected under dual observation axes into the high-frequency voltage equation yields the solution. High-frequency current in shaft system The expression is: ; In the formula, It serves as a high-frequency response current reference; Mainly coupled inductor; It is a secondary coupled inductor; It is a common-mode inductor; For differential inductors, these parameters can be expressed as follows: ; ; Defined as bias perturbation signal This is caused by the asymmetry of the coupled inductance and can be expressed as: In traditional single-axis high-frequency square wave injection methods, bias disturbance signals will exist in the position tracking deviation signal. This severely degrades the accuracy of position observation. By employing alternating high-frequency signal injection in a dual-axis system, the difference in self-inductance and mutual inductance between windings is utilized to achieve bias disturbance signal within the high-frequency injection cycle. Half-wave antisymmetry; Step 3: Based on the amplitude-frequency analytical calculation results of the high-frequency current components of the single-axis system, a bandpass filter is used to extract the current component with a higher signal-to-noise ratio (SNR) at the injection frequency from the high-frequency current for position tracking deviation signal reconstruction, thereby eliminating the bias disturbance in the original position tracking deviation signal.

[0016] Combination Figure 3As shown, based on the high-frequency response current amplitude-frequency analytical calculation results, the component of one-time injection frequency is extracted to reconstruct the position tracking deviation signal: High frequency current From DC component Odd harmonic components Even frequency components The composition, calculated through amplitude-frequency analysis, is as follows: ; ; In the formula, For component order; The angular frequency of the injected high-frequency signal; and They are respectively in Shaft system and When the shaft system is subjected to high-frequency voltage injection The response amplitudes can be expressed as follows: ; In the formula, for The amplitude.

[0017] Step 4: Input the reconstructed position tracking deviation signal into a proportional-integral phase-locked loop to obtain the rotor position and speed, thereby ultimately achieving sensorless control and improving position observation accuracy.

[0018] High-frequency current is extracted using a bandpass filter. One-time injection frequency component Its expression is: ; Will Shaft system next injection frequency component and Shaft system next injection frequency component Transform to a measuring axis system that is 45° out of phase to obtain the measuring axis system. The expression for high-frequency current in the shaft system is: ; The reconstructed position tracking deviation signal It can be represented as: ; In the formula, and High frequency current and The amplitude of the reconstructed position tracking deviation signal. The bias disturbance signal was eliminated. By inputting this information into a proportional-integral phase-locked loop (PLL), the rotor position and speed can be observed, and the accuracy of position observation can be improved.

[0019] To further verify the beneficial effects of the present invention, a specific embodiment is described below: The experiment was conducted on a dual three-phase permanent magnet synchronous motor (PMSM) tractor platform. A 3-kW PMSM was coaxially connected to an induction motor, with the induction motor providing the load torque. The main parameters of the PMSM used were: rated voltage 380 V, rated current 2.2 A, rated torque 19 N∙m, rated speed 1500 r / min, stator resistance 2.5 Ω, d-axis inductance 9.03 mH, q-axis inductance 13.3 mH, leakage inductance 1.5 mH, and number of pole pairs 2. A high-frequency square wave voltage with a frequency of 625 Hz and an amplitude of 12.5 V was alternately injected into the dual observation axis system.

[0020] Figure 4 The figure shows the steady-state operation results of a single-shaft system with high-frequency voltage injection under 62.5% rated load. It can be observed that the observed rotor position successfully tracks the actual rotor position, but there is a significant observation error of -22.12°. At this point, the position observation error is too large, and further increasing the load will lead to system instability.

[0021] Figure 5 The figure shows the steady-state operation results when using this method at 100% rated load. At this point, the rotor position observation error is relatively small, with a magnitude of -5.23°. Compared with single-shaft injection, the proposed method improves the position observation accuracy by more than 75% and increases the load-carrying capacity by more than 30% while ensuring system stability, enabling stable operation at 100% rated load.

[0022] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A sensorless control method for low-speed dual three-phase permanent magnet synchronous motors, characterized in that, Includes the following steps: Step 1: Establish a high-frequency voltage model of a dual three-phase permanent magnet synchronous motor considering the coupled inductance and its asymmetry under the observation axis; Step 2: Design a dual-observation-axis alternating high-frequency square wave voltage signal injection method, and use the difference between the self-inductance and mutual inductance effects between windings to achieve half-wave antisymmetry of the bias disturbance signal caused by the asymmetry of the coupled inductance within the high-frequency injection cycle; Step 3: Based on the amplitude-frequency analytical calculation results of the components of the high-frequency current in a single-axis system, a bandpass filter is used to extract the current component with a higher signal-to-noise ratio at the injection frequency from the high-frequency current for position tracking deviation signal reconstruction, thereby eliminating the bias disturbance in the original position tracking deviation signal. Step 4: Input the reconstructed position tracking deviation signal into a proportional-integral phase-locked loop to obtain the rotor position and speed, thereby ultimately achieving sensorless control and improving position observation accuracy.

2. The low-speed sensorless control method for a dual three-phase permanent magnet synchronous motor according to claim 1, characterized in that, In step 1, the high-frequency voltage model considering the coupled inductance and its asymmetry under the observation axis is as follows: ； In the formula, For the high-frequency voltage vector of the γ1-δ1 axis system, For the high-frequency voltage vector of the γ2-δ2 axis system, For the high-frequency current vector of the γ1-δ1 axis system, For the high-frequency current vector of the γ2-δ2 axis system, For differential operators, This represents the position estimation error; Let dq be the self-inductance matrix of the axis system; Let dq be the mutual inductance matrix of the axis system; The four-dimensional coordinate transformation matrix is ​​represented as follows: ； ； ； ； In the formula, For the γ1 axis high-frequency voltage; For the γ2 axis high-frequency voltage; For the high-frequency current of the γ1 axis; For high-frequency current in the γ2 axis system; , , and These are the self-inductance and mutual inductance of the dq axis system, where... , , Leakage; This is the coupling inductance between the dq axis and the same winding. The ratio of the coupling inductance between the dq axis systems of the same winding to the coupling inductance between the dq axis systems of different windings indicates an inherent asymmetry in the coupling inductance between the windings of a dual three-phase permanent magnet synchronous motor. ; It is a two-dimensional coordinate transformation matrix; It is a zero matrix.

3. The low-speed sensorless control method for a dual three-phase permanent magnet synchronous motor according to claim 2, characterized in that, In step 2, the high-frequency square wave voltage signal injected under the dual observation axis is: ； In the formula, This represents the amplitude of a high-frequency square wave voltage. The period of a high-frequency square wave voltage; For a unit amplitude period signal, it is represented as: ； for Delay Periodic signals after a certain time; Substituting the expression for the alternating high-frequency square wave voltage injected under dual observation axes into the high-frequency voltage equation, we can solve for... High-frequency current in shaft system The expression is: ； In the formula, It serves as a high-frequency response current reference; Mainly coupled inductor; It is a secondary coupled inductor; It is a common-mode inductor; For differential inductors, these parameters are expressed as follows: ； ； Defined as bias perturbation signal It is caused by the asymmetry of the coupled inductance and is expressed as .

4. The low-speed sensorless control method for a dual three-phase permanent magnet synchronous motor according to claim 3, characterized in that, In step 3, high-frequency current From DC component Odd harmonic components Even frequency components The composition, calculated through amplitude-frequency analysis, is as follows: ； ； In the formula, For component order; The angular frequency of the injected high-frequency signal; and They are respectively in Shaft system and When the shaft system is subjected to high-frequency voltage injection The response amplitudes are expressed as follows: ； In the formula, for The amplitude.

5. The low-speed sensorless control method for a dual three-phase permanent magnet synchronous motor according to claim 4, characterized in that, In step 4, a bandpass filter is used to extract the high-frequency current. One-time injection frequency component Its expression is: ； Will Shaft system next injection frequency component and Shaft system next injection frequency component Transform to a measuring axis system that is 45° out of phase to obtain the measuring axis system. The expression for high-frequency current in the shaft system is: ； The reconstructed position tracking deviation signal Represented as: ； In the formula, and High frequency current and The amplitude; Will The input is fed into a proportional-integral phase-locked loop to observe the rotor position and speed.

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