Hybrid excitation motor two-phase static coordinate system sensorless control method and system

Abstract

The invention discloses a hybrid excitation motor two-phase static coordinate system position-sensorless control method and a hybrid excitation motor two-phase static coordinate system position-sensorless control system. The method comprises the following steps of: firstly, applying high-frequency square wave voltage excitation in an excitation winding, detecting generated high-frequency response current under a two-phase static coordinate system by utilizing a carrier separation mathematical method, and discretizing a detected high-frequency response current signal; then, the discrete current signals are processed through vector cross multiplication and a sign function, and rotor position and rotating speed information is obtained; and finally, substituting the real-time estimated values of the rotor position and the rotating speed into a vector control system of the hybrid excitation motor to control the hybrid excitation motor. According to the method, the precision of rotor position estimation under the zero-low-speed working condition is improved, dependence on a complex filter is not needed, the bandwidth of the system is expanded, and the control performance of the motor system is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of motor control, and particularly to a sensorless control method for a hybrid-excitation motor in a two-phase stationary coordinate system. Background Art

[0002] With the continuous development of motor control technology, sensorless control methods are of great significance in reducing costs, simplifying structures, and improving system reliability. However, traditional sensorless control methods mainly rely on motor back-electromotive force information, which can achieve relatively accurate rotor position estimation under medium and high-speed operating conditions. However, in the zero-speed and low-speed regions, due to the extremely low amplitude of the motor back-electromotive force and the sharp decline in the signal-to-noise ratio, the estimation accuracy of the rotor position and speed is severely limited, making it difficult to meet the requirements of smooth motor starting and stable low-speed operation.

[0003] In response to this, the high-frequency signal injection technology extracts rotor position and speed information by applying an external high-frequency signal to the motor winding and utilizing the response characteristics of the motor magnetic circuit to the high-frequency signal. Traditional high-frequency square-wave injection methods are mainly implemented based on a two-phase rotating coordinate system. However, when using a two-phase rotating coordinate system, electrical quantities require obtaining electrical angle information, and problems such as slow convergence speed or even non-convergence of the observed angle may occur during the algorithm iteration process. In addition, traditional high-frequency square-wave injection methods separate high-frequency signals from fundamental-frequency signals through a filter, and then estimate the rotor position based on the filtered high-frequency response signal. However, due to the inherent bandwidth limitation and filter phase delay problems in the filtering process, such methods are prone to introducing large time delays and errors during high-speed dynamic response and low-speed starting, affecting the response speed and stability of the overall control system. Summary of the Invention

[0004] The purpose of the present invention is to provide a sensorless control method and system for a hybrid-excitation motor with high control accuracy, strong stability, fast response speed, and strong real-time performance.

[0005] The technical solution to achieve the purpose of the present invention is: A sensorless control method for a hybrid-excitation motor in a two-phase stationary coordinate system, comprising the following steps:

[0006] Step 1: By applying a high-frequency square-wave voltage excitation to the excitation winding, detect the generated high-frequency response current i αh 、i βh in the two-phase stationary coordinate system using a carrier separation mathematical method;

[0007] Step 2: Discretize the detected high-frequency response current signal;

[0008] Step 3: Process the discretized current signal using vector cross product and sign function to obtain rotor position and speed information;

[0009] Step 4: Substitute the real-time estimated values of the rotor position and speed into the vector control system of the hybrid excitation motor to control the hybrid excitation motor.

[0010] Furthermore, in Step 1, by applying a high-frequency square-wave voltage excitation to the excitation winding, the high-frequency response currents i αh and i βh generated are detected in the two-phase stationary coordinate system by using the carrier separation mathematical method, specifically as follows:

[0011] Step 1.1: Apply a high-frequency square-wave voltage excitation to the excitation winding:

[0012] u fh = (-1) k U inj

[0013] where u fh is the high-frequency square-wave voltage excitation; U inj is the amplitude of the high-frequency injection voltage; k is the sampling time series;

[0014] Step 1.2: The carrier separation mathematical method regards the response current component as composed of the high-frequency current component i h and the fundamental-frequency current component i f superimposed. The sampling values at three adjacent sampling moments are used to separate the fundamental-frequency signal and the high-frequency signal. The formula is:

[0015]

[0016] where i αβf (k) and i αβh (k) are the fundamental-frequency current component and the high-frequency current component in the two-phase stationary coordinate system at the k-th moment respectively; i αβ (k) is the response current component in the two-phase stationary coordinate system at the k-th moment;

[0017] Step 1.3: Through coordinate transformation and the carrier separation mathematical method, the high-frequency response currents i αh and i βh generated by the motor in the two-phase stationary coordinate system are obtained. The formula is:

[0018]

[0019] where p is the differential operator; M sfh is the amplitude of the high-frequency mutual inductance between the armature winding and the excitation winding; L dh is the amplitude of the high-frequency direct-axis inductance of the armature winding; L qh is the amplitude of the high-frequency inductance of the excitation winding; θ is the electrical angle.

[0020] Further, the discretization process of the detected high-frequency response current signal in step 2 is carried out according to the formula:

[0021]

[0022] In the formula, Δi αh and Δi βh are the differences of the high-frequency response currents in the two-phase stationary coordinate system within adjacent sampling periods respectively; T s is the sampling period.

[0023] Further, the discrete current signal is processed using vector cross product and sign function in step 3 to obtain the rotor position and speed information, specifically as follows:

[0024] Step 3.1: The position error decoupling is carried out using the method of vector cross product, and the formula is:

[0025]

[0026] In the formula, is the observed position angle; θ err is the difference between the true position angle and the observed position angle;

[0027] Step 3.2: After decoupling by the sign function, the error between the actual rotor position and the observed position is:

[0028]

[0029] In the formula, e is the rotor position error function; sgn() is the sign function.

[0030] Further, in step 4, when the observed rotor position converges to the true position, the position error signal θ err tends to 0, and θ err is put into the phase-locked loop structure to track and extract the motor rotor position signal and speed signal.

[0031] A sensorless control system for a hybrid excitation motor in a two-phase stationary coordinate system, which is used to implement the sensorless control method of the hybrid excitation motor. The system includes a first module to a fourth module, where:

[0032] The first module applies a high-frequency square wave voltage excitation to the excitation winding and detects the generated high-frequency response currents i αh and i βh in the two-phase stationary coordinate system by using the carrier separation mathematical method;

[0033] The second module discretizes the detected high-frequency response current signal;

[0034] The third module processes the discretized current signal using vector cross product and sign function to obtain the rotor position and speed information;

[0035] The fourth module substitutes the real-time estimated values of the rotor position and speed into the vector control system of the hybrid excitation motor to control the hybrid excitation motor.

[0036] A mobile terminal includes a memory, a processor, and a computer program stored on the memory and executable on the processor. When the processor executes the program, the sensorless control method for the hybrid excitation motor is implemented.

[0037] A computer-readable storage medium stores a computer program thereon. When the program is executed by a processor, the steps in the sensorless control method for the hybrid excitation motor are implemented.

[0038] Compared with the prior art, the significant advantages of the present invention are as follows: (1) By injecting a high-frequency square-wave voltage signal into the excitation winding and adopting a carrier separation mathematical method independent of filters based on the current response in the two-phase stationary coordinate system, high-precision extraction of the rotor position information of the hybrid excitation motor is achieved; (2) Utilizing the magnetic coupling characteristics between the motor excitation winding and the armature winding, even under zero and low-speed operating conditions, even when the back electromotive force amplitude of the motor is extremely low and the signal-to-noise ratio drops significantly, the rotor position and speed information contained in the high-frequency response current in the two-phase stationary coordinate system can be effectively captured, avoiding the problem that the observation angle convergence speed may be slow or even non-convergent in the algorithm iteration process of the traditional high-frequency injection method based on the two-phase rotating coordinate system; (3) Adopting the carrier separation mathematical method avoids the dynamic response problems caused by the limited filter bandwidth and phase delay, improving the real-time performance and response speed of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 It is a vector control diagram of the sensorless control method for the two-phase stationary coordinate system of the hybrid excitation motor of the present invention.

[0040] Figure 2 It is a flowchart of the mathematical calculation for separating the carrier signal in the present invention.

[0041] Figure 3 It is a structural block diagram of the equivalent structure of the phase-locked loop in the present invention.

[0042] Figure 4 It is a simulation result diagram of the motor rotor position in the embodiment of the present invention.

[0043] Figure 5 It is a simulation result diagram of the motor speed in the embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0044] A sensorless control method for a hybrid excitation motor in a two-phase stationary coordinate system according to the present invention realizes accurate tracking of the motor rotor position signal by injecting a high-frequency square wave voltage signal into the excitation winding. Due to the special magnetic circuit structure of the motor and the spatial coupling relationship between the excitation winding and the main armature winding, when a high-frequency square wave voltage is applied to the excitation winding, the high-frequency response current driven by the square wave signal will generate a high-frequency changing magnetic flux through the excitation winding. This high-frequency magnetic flux is further coupled to the stator armature winding of the motor, resulting in the armature winding current containing rotor position information. As the rotor position changes, the asymmetry of the internal magnetic circuit of the motor and the change of the coupling coefficient enable the armature winding current to effectively reflect the rotor position, thereby providing a reliable position signal for the sensorless control system.

[0045] As Figure 1 shown, a sensorless control method for a hybrid excitation motor in a two-phase stationary coordinate system according to the present invention includes the following steps:

[0046] Step 1: Apply a high-frequency square wave voltage excitation to the excitation winding, and detect the generated high-frequency response current i αh 、i βh in the two-phase stationary coordinate system by using the carrier separation mathematical method;

[0047] Step 2: Discretize the detected high-frequency response current signal;

[0048] Step 3: Process the discretized current signal by using vector cross product and sign function to obtain the rotor position and speed information;

[0049] Step 4: Substitute the real-time estimated values of the rotor position and speed into the vector control system of the hybrid excitation motor to control the hybrid excitation motor.

[0050] As a specific example, in Step 1, a high-frequency square wave voltage excitation is applied to the excitation winding, and the generated high-frequency response current i αh 、i βh is detected in the two-phase stationary coordinate system by using the carrier separation mathematical method as follows:

[0051] Step 1.1: Apply a high-frequency square wave voltage excitation to the excitation winding:

[0052] u fh =(-1) k U inj

[0053] where u fh is the high-frequency square wave voltage excitation; U inj is the amplitude of the high-frequency injection voltage; k is the sampling time series.

[0054] Step 1.2. The carrier separation mathematical method can regard the response current component as composed of a high-frequency current component \(i\) h and a fundamental-frequency current component \(i\) f superimposed. The sampling values at three adjacent sampling moments are used to separate the fundamental-frequency signal and the high-frequency signal. The formula is:

[0055]

[0056] In the formula, \(i\) αβf (k) and \(i\) αβh (k) are the fundamental-frequency current component and the high-frequency current component in the two-phase stationary coordinate system at the \(k\)th moment respectively; \(i\) αβ (k) is the response current component in the two-phase stationary coordinate system at the \(k\)th moment.

[0057] Step 1.3. As Figure 2 shown, through coordinate transformation and the carrier separation mathematical method, the high-frequency response current \(i\) αh and \(i\) βh generated by the motor in the two-phase stationary coordinate system are obtained. The formula is:

[0058]

[0059] In the formula, \(p\) is the differential operator; \(M\) sfh is the amplitude of the high-frequency mutual inductance between the armature winding and the field winding; \(L\) dh is the amplitude of the high-frequency direct-axis inductance of the armature winding; \(L\) qh is the amplitude of the high-frequency inductance of the field winding; \(\theta\) is the electrical angle.

[0060] As a specific example, in Step 2, the detected high-frequency response current signal is discretized. The formula is:

[0061]

[0062] In the formula, \(\Delta i\) αh and \(\Delta i\) βh are the differences in the high-frequency response current in the two-phase stationary coordinate system within adjacent sampling periods respectively; \(T\) s is the sampling period.

[0063] As a specific example, in Step 3, the discretized current signal is processed using vector cross product and sign function to obtain the rotor position and speed information, specifically as follows:

[0064] Step 3.1. The method of vector cross product is used for position error decoupling. The formula is:

[0065]

[0066] In the formula, is the observed position angle; \(\theta\)err is the difference between the real position angle and the observed position angle.

[0067] Step 3.2: After decoupling by the sign function, the error between the actual rotor position and the observed position is obtained as:

[0068]

[0069] In the formula, e is the rotor position error function; sgn() is the sign function.

[0070] As a specific example, in Step 4, the real-time estimated values of the rotor position and speed are substituted into the vector control system of the hybrid excitation motor to control the hybrid excitation motor, specifically as follows:

[0071] As Figure 3 shown, when the observed rotor position converges to the real position, the position error signal θ err approaches 0, and it can be put into the phase-locked loop structure to track and extract the motor rotor position signal and speed signal.

[0072] The present invention also provides a sensorless control system for a hybrid excitation motor in a two-phase stationary coordinate system, which is used to implement the sensorless control method of the hybrid excitation motor. The system includes a first module to a fourth module, where:

[0073] The first module applies a high-frequency square wave voltage excitation to the excitation winding, and uses the carrier separation mathematical method to detect the generated high-frequency response currents i αh 、i βh in the two-phase stationary coordinate system;

[0074] The second module discretizes the detected high-frequency response current signal;

[0075] The third module processes the discretized current signal using vector cross multiplication and the sign function to obtain the rotor position and speed information;

[0076] The fourth module substitutes the real-time estimated values of the rotor position and speed into the vector control system of the hybrid excitation motor to control the hybrid excitation motor.

[0077] The present invention also provides a mobile terminal, including a memory, a processor, and a computer program stored on the memory and executable on the processor. When the processor executes the program, the sensorless control method of the hybrid excitation motor is implemented.

[0078] The present invention also provides a computer-readable storage medium, on which a computer program is stored. When the program is executed by the processor, the steps in the sensorless control method of the hybrid excitation motor are implemented.

[0079] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0080] Embodiment

[0081] In this embodiment, according to Figure 1 the vector control system shown, a simulation model is built in the MATLAB / Simulink environment with the following parameters: the rated power of the hybrid excitation motor is 2 kW, the number of pole pairs is 10, the rated voltage is 220 V, the mutual inductance between the excitation winding and the armature winding is 0.04 mH, the rated speed is 2000 rpm, the model sampling frequency is set to 10 kHz, a high-frequency square-wave voltage signal with a frequency of 5 kHz and an amplitude of 20 V is injected into the excitation winding, the motor load is 2 Nm, and the given speed is 100 rpm.

[0082] The simulation results are as shown in Figure 4 and Figure 5 It can be seen that during stable operation, this method can accurately obtain the rotor position and motor speed of the hybrid excitation motor, realizing high-precision extraction of the rotor position information of the hybrid excitation motor. Even when the amplitude of the motor back electromotive force is extremely low and the signal-to-noise ratio drops significantly, it can effectively capture the rotor position and speed information contained in the high-frequency response current in the two-phase stationary coordinate system, avoiding the problem that the observation angle convergence speed may be slow or even non-convergent in the algorithm iteration process of the traditional high-frequency injection method based on the two-phase rotating coordinate system, avoiding the dynamic response problems caused by the limited filter bandwidth and phase delay, and improving the real-time performance and response speed of the system.

[0083] The above is only the preferred embodiment of the present invention. It should be pointed out that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A sensorless control method for a hybrid excitation motor in a two-phase stationary coordinate system, characterized in that, Including the following steps: Step 1: By applying a high-frequency square-wave voltage excitation to the excitation winding, use the carrier separation mathematical method to detect the generated high-frequency response currents i αh 、i βh ; Step 2. Discretize the detected high-frequency response current signal; Step 3. Process the discretized current signal using vector cross product and sign function to obtain rotor position and speed information; Step 4. Substitute the real-time estimated values of rotor position and speed into the vector control system of the hybrid excitation motor to control the hybrid excitation motor.

2. The sensorless control method for a hybrid excitation motor according to claim 1, wherein The high-frequency response current i generated by applying a high-frequency square-wave voltage excitation to the excitation winding in Step 1 and detecting it in the two-phase stationary coordinate system by using the carrier separation mathematical method αh and i βh are as follows: Step 1.

1. Apply a high-frequency square-wave voltage excitation to the excitation winding: u fh = (-1) k U inj where u fh is the high-frequency square-wave voltage excitation; U inj is the amplitude of the high-frequency injection voltage; k is the sampling time series; Step 1.

2. The carrier separation mathematical method regards the response current component as being composed of a high-frequency current component i h and a fundamental frequency current component i f superimposed. The sampling values at three adjacent sampling moments are used to separate the fundamental frequency signal and the high-frequency signal. The formula is as follows: where i αβf (k) and i αβh (k) are the fundamental frequency current component and the high frequency current component in the two-phase stationary coordinate system at the k-th moment, respectively; i αβ (k) is the response current component in the two-phase stationary coordinate system at the k-th moment; Step 1.3: Through coordinate transformation and carrier separation mathematical methods, the high-frequency response current i αh and i βh generated by the motor in the two-phase stationary coordinate system are obtained. The formula is as follows: where p is the differential operator; M sfh is the high-frequency mutual inductance amplitude between the armature winding and the field winding; L dh is the high-frequency direct-axis inductance amplitude of the armature winding; L qh is the high-frequency inductance amplitude of the field winding; θ is the electrical angle.

3. The sensorless control method of the hybrid excitation motor according to claim 1, wherein The discretization process of the detected high-frequency response current signal described in Step 2 has the formula: where Δi αh and Δi βh are the differences in high-frequency response currents in the two-phase stationary coordinate system during adjacent sampling periods; T s is the sampling period.

4. The sensorless control method of the hybrid excitation motor according to claim 1, characterized in that The process of using vector cross product and sign function to process the discretized current signal described in Step 3 to obtain rotor position and speed information is as follows: Step 3.

1. Use the method of vector cross product to decouple the position error, and the formula is: In the formula, is the observation position angle; θ err is the difference between the true position angle and the observation position angle; Step 3.

2. After decoupling through the sign function, the error between the actual rotor position and the observed position is: In the formula, e is the rotor position error function; sgn() is the sign function.

5. The sensorless control method for a hybrid excitation motor according to claim 1, wherein In step 4, when the observed position of the rotor converges to the true position, the position error signal θ err approaches 0, and θ err is put into the phase-locked loop structure to track and extract the motor rotor position signal and speed signal.

6. A sensorless control system for a hybrid excitation motor in a two-phase stationary coordinate system, characterized in that, This system is used to implement the sensorless control method for the hybrid excitation motor described in any one of claims 1 to 5. The system includes a first module to a fourth module, where: The first module detects the generated high-frequency response currents i αh and i βh by applying a high-frequency square-wave voltage excitation to the excitation winding and using the carrier separation mathematical method in the two-phase stationary coordinate system; The second module discretizes the detected high-frequency response current signal; The third module processes the discretized current signal using vector cross product and sign function to obtain rotor position and speed information; The fourth module substitutes the real-time estimated values of rotor position and speed into the vector control system of the hybrid excitation motor to control the hybrid excitation motor.

7. A mobile terminal, comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, characterized in that, When the processor executes the program, it implements the sensorless control method for the hybrid excitation motor described in any one of claims 1 to 5.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the program is executed by the processor, it implements the steps in the sensorless control method for the hybrid excitation motor described in any one of claims 1 to 5.

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