FSPM motor sensorless control method based on magnetic induction salient polarity

Abstract

The invention discloses an FSPM motor sensorless control method based on magnetic induction salient polarity, and aims to hinder sensorless control depending on magnetic resistance salient polarity due to small equivalent magnetic resistance salient polarity caused by a magnetic field modulation effect and low salient pole rate Lq / Ld of an FSPM motor. According to the invention, the short-circuit coil is added in the stator of the FSPM motor, and a new magnetic induction salient polarity is introduced, i.e., the d-axis magnetic induction and the q-axis magnetic induction are not equal. Therefore, the salient pole rate of the FSPM motor is increased. Besides, the multi-salient-polarity problem also deteriorates the estimation performance of the position angle of the FSPM motor, and generates negative effects on position sensorless control, especially when the salient pole rate of the motor is relatively low. The problem is solved by applying a position observer based on a second-order generalized integrator with a frequency phase-locked loop, and sensorless control is realized by feeding back the estimated speed and position angle to a vector control system of the FSPM motor.

Description

Technical Field

[0001] The present invention belongs to the technical field of motor control, and in particular relates to a position sensorless control method of a FSPM (Flux Switching Permanent Magnet) motor based on magnetic induction saliency. Background Art

[0002] In recent years, FSPM motors are expected to replace traditional permanent magnet synchronous motors in the fields of electric vehicles and wind power generation due to their high efficiency, high torque density, and robust stator and rotor structures. Like traditional permanent magnet synchronous motors, the high-performance operation of FSPM motors also requires high-precision position sensors. However, position sensors increase costs and reduce the robustness of the control system. Therefore, as an effective solution, position sensorless control technology has been widely discussed and studied by scholars at home and abroad.

[0003] Considering that the FSPM motor has similarities with the traditional permanent magnet synchronous motor in mathematical model, many research results on permanent magnet synchronous motor can be used for reference. Generally, position sensorless control can be divided into model-based methods and salient polarity-based methods. Such model-based methods include sliding mode observers, disturbance observers, and extended Kalman filters, which obtain rotor position information from the back electromotive force or flux of the motor. However, in the low-speed area, the signal-to-noise ratio of the back electromotive force and flux is low, and these observer-based position sensorless control methods may fail. The salient polarity-based method mainly utilizes the difference in inductance between the direct axis and the quadrature axis of the motor. According to the type of injected signal, these salient polarity-based methods can be divided into rotating high-frequency signal injection and pulsating high-frequency signal injection. Generally speaking, since the rotating high-frequency injection method injects the high-frequency signal into the stationary coordinate system, the stability of the rotating high-frequency injection method is better than that of the pulsating high-frequency injection method. However, compared with the pulse high-frequency signal injection method, the rotating high-frequency signal injection is more sensitive to resistive disturbances such as phase resistance, eddy current equivalent resistance and inverter nonlinearity, so the position estimation accuracy of the pulse high-frequency signal injection method is better.

[0004] The rotor and stator of the FSPM motor are both salient pole structures. Intuitively, the magnetic resistance of the direct axis and quadrature axis of the FSPM motor should be large, thus having a high salient pole ratio ( L q / L d ).but, L d and L qThe values ​​between them are generally not much different. This has been explained by related research work using magnetic field modulation theory. The low saliency hinders the implementation of the saliency-based position sensorless method on FSPM motors. In addition, due to magnetic saturation and its body structure, there may be multiple saliency problems in FSPM motors, that is, L q / L d Varies with rotor position. Summary of the invention

[0005] Technical problem: The purpose of the present invention is to provide a FSPM motor position sensorless control method based on magnetic induction saliency, so as to solve the problem that the FSPM motor has the characteristics of too low salient pole ratio and multiple salient pole ratio, which makes the high-frequency injection method difficult to implement. The present invention adds a short-circuit coil to the FSPM motor and introduces magnetic induction saliency into the motor, thereby realizing high-frequency injection positionless control based on magnetic induction saliency, reducing the cost of the control system and improving the robustness of the system.

[0006] Technical solution: A position sensorless control method for FSPM motor based on magnetic saliency adopted by the present invention comprises the following steps: Step 1: According to the vector magnetic circuit theory, a magnetic induction element - a short-circuit coil is added to the magnetic circuit to change the inductance; Step 2, arranging coils in the FSPM motor, and connecting the coils in reverse series in sequence, and then short-circuiting the entire coil to form a short-circuited coil; Step 3, in the stationary coordinate system α High-frequency pulse voltage is injected into the shaft; Step 4, using finite element software ANSYA, analyzing the relationship between the loss and flux after adding the short-circuit coil and the number of turns of the short-circuit coil to determine the value range of the number of turns of the short-circuit coil; Step 5: Sample the stationary coordinate system β The shaft current is measured and the high-frequency response current containing the position angle information is extracted through the traditional signal demodulation method. The estimated position angle and speed information are obtained through the second-order generalized integrator SOGI-FLL with frequency-locked loop and the phase-locked loop. Step 6: The motor control strategy adopts the traditional rotor field oriented control method, and uses the estimated speed and position as feedback signals to replace the actual measured speed and position.

[0007] The vector magnetic circuit theory and magnetic induction element in step 1, The magnetic circuit equation after introducing magnetic induction into the magnetic circuit is expressed as: , Where: m represents the magnetic circuit, represents the magnetic induction of the magnetic circuit, represents the magnetic resistance of the magnetic circuit, The magnetic flux of the magnetic circuit, is the imaginary number symbol, represents the magnetomotive force of the magnetic circuit, is the angular frequency of the variable in the magnetic circuit; the magnetic induction is considered to be the reflection of the short-circuited coil in the magnetic circuit, so the magnetomotive force is written as , In the formula, represents the number of turns of the short-circuited coil, Represents the current of the short-circuited coil, combining the above two equations to obtain: , Then, define the complex inductance as ; Therefore, the new relationship between magnetic flux and current is expressed as: , In the formula, Represents magnetic flux. In order to more intuitively show the relationship between inductance and complex inductance, the traditional inductance formula Substituting into the above formula, we get: , In the formula, Represents the inductance. Obviously, when When the complex inductance Equal to inductance ,when When the complex inductance The amplitude approaches 0, through the motor d Axis is a straight axis or q The direction of the axis or the cross axis increases the magnetic induction and can adjust the high frequency d Axis or q The size of the shaft inductance can meet the requirements of realizing the sensorless control algorithm based on high frequency injection. d Shaft Inductance L d No wait q Shaft inductance L q .

[0008] In the short-circuit coil in step 2, first, the winding function of the short-circuit coil is expressed as: , Where: represents the number of pole pairs of the winding function, θ is the mechanical angle defined on the stator, with the subscript Indicates a short-circuited coil. It corresponds to The coefficient of the harmonic function of the secondary short-circuit coil winding. Similarly, the winding function of phase A is expressed as: , in, represents the pole pair number of the A-phase winding function, It corresponds to The coefficient of the harmonic function of the A-phase winding is then obtained according to the three-phase distribution of the winding. Under the premise of ignoring the magnetic resistance and saturation of ferromagnetic materials, when the rotor is smooth and the stator core is slotted, the air gap permeability It is expressed as: , Where: represents the DC component, It corresponds to The coefficient of the sub-harmonic permeance, Z s Indicates the number of stator poles. Similarly, when the stator is smooth and the rotor core is slotted, the air gap permeance It can be expressed as: , in, represents the DC component, It corresponds to The coefficient of the sub-harmonic permeance, Z r represents the number of rotor poles, θ r represents the position angle of the rotor. Then, when both the rotor and stator cores are slotted, the air gap permeance is as follows: , Then, the inductance of the short-circuited coil is expressed as: , in, and Respectively represent the stator inner diameter and the effective length of the lamination, the subscript Can be subscribed , b , c , Any replacement, represent The mutual inductance of the phase winding and the short-circuited coil; in order to change the FSPM motor by short-circuiting the coil d The magnetic induction of the shaft and the self-inductance of the short-circuited coil must be the same as the rotor position angle Unrelated, first of all, the self-inductance of the short-circuited coil It is expressed as: , It is expressed as: , Where: and They are respectively Second and The coefficients of the harmonic function of the secondary short-circuit coil winding are, according to the orthogonality of trigonometric functions, and The integral on the interval from 0 to 2π must satisfy the following conditions to be non-zero: , Therefore, for a specific FSPM motor, this condition is used to select the number of pole pairs of the winding function of the short-circuit coil to meet and rotor position angle θ r Regardless, then according to the constraints q Mutual inductance of shaft winding and short-circuit coil Equal to 0 to design the connection method of the short-circuit coil.

[0009] In step 3, a high-frequency sinusoidal voltage is injected into the stationary coordinate system. α axis, compared to the injection into the rotating coordinate system d On the axis, the high-frequency voltage injection scheme adopted has stronger robustness.

[0010] The value range of the number of short-circuit coil turns in step 4 is as follows: adding a short-circuit coil to the FSPM motor will cause losses, so the selection of the number of short-circuit coil turns needs to consider the size of the losses. The finite element software ANSYS is used to simulate and analyze the specific FSPM motor, and a trade-off is made between the size of the magnetic saliency introduced by the short-circuit coil and the losses in the short-circuit coil, thereby determining the number of turns of the short-circuit coil.

[0011] After the SOGI-FLL processing in step 5, the estimated position angle and speed information are obtained through the phase-locked loop. The input of SOGI-FLL is expressed as: , Where: Represents a high-frequency current signal containing position angle information, represents the harmonic order, Representative is The magnitude of the secondary component, represents the electrical angle of the rotor, represents the initial phase angle, and the transfer function of SOGI is expressed as: , , Where: represent After the signal is filtered by SOGI-FLL, Yes and The corresponding quadrature signal, is the filter coefficient of SOGI-FLL, is the center frequency, is a bandpass filter type transfer function with a center frequency of , at the same time, at the center frequency The transfer function at Equivalent to an integrator; SOGI can be The harmonics are eliminated and SOGI can build a The signals have the same amplitude but a 90° phase difference. In order to improve the dynamic performance of SOGI and make it frequency adaptive, a frequency-locked loop (FLL) is applied. At the same time, the feedforward frequency related to the reference speed is added to the control loop to make the velocity estimation faster, when SOGI-FLL reaches steady state, its output is expressed as: , , in, A is the amplitude, and the estimated position is obtained through the phase-locked loop PLL .

[0012] In step 6, the estimated speed and position are used as feedback signals to replace the speed and position angle actually measured. Traditional magnetic field oriented control requires accurate speed and position angle information. Therefore, replacing the actual measured values ​​with the estimated speed and position angle and bringing them into the magnetic field oriented control can realize position sensorless control of the system.

[0013] Beneficial effects: The present invention has the following advantages: 1) The saliency rate of FSPM motor is low, which makes the traditional high-frequency injection position sensorless control method based on magnetic resistance saliency fail. The present invention adds a short-circuit coil to the FSPM motor and introduces magnetic induction saliency into the motor, thereby realizing high-frequency injection positionless control based on magnetic induction saliency, reducing the cost of the control system and improving the robustness of the system.

[0014] 2) A position estimator based on SOGI-FLL is designed to solve the problem of harmonics in the position observation angle caused by multiple salient poles in the FSPM motor.

[0015] 3) The present invention is also applicable to the position-free control of FSPM motors with other rotary or linear structures. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 The model diagram of the FSPM motor; (a) is a two-dimensional topological diagram; (b) is a three-dimensional model diagram; A1 and A2 are a pair of windings, B1 and B2 are a pair of windings, and C1 and C2 are a pair of windings; Figure 2 Figure 1 is a magnetic circuit model diagram; Figure (a) is a traditional magnetic circuit model of a single magnetic resistance element; Figure (b) is a vector magnetic circuit model including magnetic resistance and magnetic induction elements; Figure 3 Figure 1 is a diagram of the installation and connection method of the short-circuit coil; Figure (a) is a diagram of the installation model of the short-circuit coil; Figure (b) is a diagram of the connection method of the short-circuit coil; Figure F1, F2, F3, F4, F5, and F6 are winding coils respectively; Figure 4 is the inductance of the short-circuit coil and its dq Equivalent diagram in the axis coordinate system; Figure (a) is the inductance diagram of the short-circuited coil; Figure (b) is the inductance diagram of the short-circuited coil in dq Equivalent diagram in the axis coordinate system; Figure 5 Figure 2 is a diagram of a traditional signal demodulation method; Figure 6 The experimental comparison diagram of the saliency test of the FSPM motor without a short-circuit coil and with a short-circuit coil; Figure (a) is the experimental diagram of the saliency test of the FSPM motor without a short-circuit coil; Figure (b) is the experimental diagram of the saliency test of the FSPM motor with a short-circuit coil; Figure 7 Figure 1 is a graph showing the relationship between high frequency loss and flux linkage and the number of turns of the short-circuit coil; Figure (a) is a graph showing the relationship between the current and flux linkage in the short-circuit coil and the number of turns of the winding; Figure (b) is a graph showing the relationship between the loss in the short-circuit coil and the number of turns of the winding; Figure 8 It is the structural block diagram of SOGI-FLL; Fig. 9 is the Bode plot of the transfer function of SOGI-FLL; Fig.10 The structure diagram of the position sensorless control strategy of the FSPM motor based on magnetic saliency; in the figure, Sa, Sb, and Sc are three-phase control signals; Fig.11 For experimental comparison between position sensorless control with and without short-circuited coils; Fig.12 The steady-state experimental diagram of the position sensorless control of the FSPM motor based on magnetic saliency; (a) is the three-phase current diagram; (b) is the performance verification of SOGI-FLL; (c) is the comparison between the actual speed and the estimated speed of the FSPM motor; (d) is the comparison between the actual position angle and the estimated position angle of the FSPM motor; Fig.13Figure 2 is a transient experimental diagram of position sensorless control of FSPM motor based on magnetic saliency; Figure (a) shows the dynamic performance of FSPM motor in starting state; Figure (b) shows the dynamic performance of FSPM motor in speed changing condition, which is a comparison between actual speed and estimated speed of FSPM motor. DETAILED DESCRIPTION

[0017] A position sensorless control method for a FSPM motor based on magnetic saliency of the present invention comprises the following steps: Step 1: According to the vector magnetic circuit theory, a magnetic induction element - a short-circuit coil is added to the magnetic circuit to change the inductance; Step 2, arranging coils in the FSPM motor, and connecting the coils in reverse series in sequence, and then short-circuiting the entire coil to form a short-circuited coil; Step 3, injecting a high-frequency pulse voltage on the α-axis in the stationary coordinate system; Step 4, using finite element software ANSYA, analyzing the relationship between the loss and flux after adding the short-circuit coil and the number of turns of the short-circuit coil to determine the value range of the number of turns of the short-circuit coil; Step 5, sampling the current on the β axis in the stationary coordinate system, and extracting the high-frequency response current containing the position angle information through the traditional signal demodulation method, and then processing it through the second-order generalized integrator SOGI-FLL with a frequency-locked loop and then through the phase-locked loop to obtain the estimated position angle and speed information; Step 6: The motor control strategy adopts the traditional rotor field oriented control method, and uses the estimated speed and position as feedback signals to replace the actual measured speed and position.

[0018] The technical solutions in the embodiments of the present invention will be described below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0019] Figure 1 This is the topology and 3D model diagram of a 6 / 19-pole FSPM motor used in this example. d The average value of the shaft inductance is q The difference in the values ​​of the shaft inductances is about 30µH and the saliency is very low, which is not conducive to position sensorless control based on high-frequency injection.

[0020] Step 1: First, in order to solve the problem of low saliency of FSPM motor, the concept of magnetic saliency is introduced. In the traditional nominal magnetic circuit, there are only magnetic resistance elements, such as Figure 2 As shown in (a) in the figure. Therefore, the size of the inductance is only related to the magnetic resistance. The salient pole ratio in traditional concepts generally refers to d Axis and q The different magnetic resistance of the axis d Axis and qHowever, in the vector magnetic circuit theory, the magnetic induction element is also an important part of the magnetic circuit, such as Figure 2 As shown in (b) in the figure. Therefore, by changing d Axis and q The magnitude of the axial magnetic induction can also change d Axis and q In order to distinguish it from the traditional concept of salient polarity based on magnetic resistance, the salient polarity caused by magnetic induction is named magnetic induction salient polarity. After the magnetic induction is introduced into the magnetic circuit, the magnetic circuit equation can be expressed as: , Where: represents the magnetic induction of the magnetic circuit. In this patent, the magnetic induction can be considered as the mapping of the short-circuited coil in the magnetic circuit. The equation can be further rewritten as , Then, define the complex inductance as Therefore, the new relationship between flux linkage and current can be expressed as: , In order to more intuitively show the relationship between inductance and complex inductance, the traditional inductance formula Substituting into the above formula we can get: , Obviously, when When the complex inductance Equal to inductance .when When the complex inductance The amplitude of approaches 0. Therefore, it can be concluded that by d Axis or q The direction of the axis increases the magnetic induction and can be adjusted at high frequencies d Axis or q The size of the shaft inductance. This satisfies the conditions for implementing the sensorless control algorithm based on high-frequency injection. .

[0021] Step 2: To differentiate d Axis and q To reduce the magnetic induction of the shaft, six coils are added to the FSPM motor and connected in series in reverse order to form a short-circuited coil. Figure 3 The installation and connection method of the short-circuit coil in the 6 / 19-pole FSPM motor is shown. According to the installation and connection method of the short-circuit coil, the winding function of the short-circuit coil can be expressed as: , Where: represents the number of pole pairs of the winding function, θ is the mechanical angle defined on the stator, with the subscript represents a short-circuited coil. Similarly, the winding function of phase A can be expressed as: , in, represents the pole pair number of the winding function of phase A. Then, according to the three-phase distribution of the winding, the winding functions of phases B and C can also be obtained. Then, ignoring the magnetic resistance and saturation of ferromagnetic materials, when the rotor is smooth and the stator core is slotted, the air gap permeance can be expressed as: , Similarly, when the stator is smooth and the rotor core is slotted, the air gap permeance can be expressed as: , in, represents magnetic permeability, Z s and Z r Represent the number of stator and rotor poles respectively. Then, when both the rotor and stator cores are slotted, the air gap permeance is as follows: , Then, the inductance of the short-circuited coil can be expressed as: , in, and Represent the inner diameter of the stator and the effective length of the laminations respectively. represent ( b , c , ). Taking the FSPM motor in the example, Z s and Z r Equal to 6 and 19 respectively. Number of pole pairs of short-circuited coil is 3. The square of can be expressed as: , therefore, The pole pair number is 3 ( u ± v ). According to the orthogonality of trigonometric functions, and The integral over the interval from 0 to 2π is valid only if 3( u ± v )=6 n ±19 m If we only consider the 0th and 1st order components, It can be expressed as: , therefore, Basically related to the rotor position θ r The inductance waveform of the short-circuited coil is as follows: Figure 4 As shown in (a) in the figure. Depends on the rotor position, when θ r It reaches its minimum value when it is equal to zero. In addition, the mutual inductance Almost unchanged, is approximately equal to zero. Therefore, in the rotating coordinate system, the short-circuited coil can be regarded as d The equivalent coil that rotates with the axis, such as Figure 4 As shown in (b) in .

[0022] Step 3: The high-frequency model of the FSPM motor in the stationary coordinate system can be expressed as: , , in, L d , L q , θ e , i , u , subscript α , β and h Respectively d Shaft inductance, q Shaft inductance, rotor electrical angle position, current, voltage, α axis, β Then, the high-frequency voltage signal is injected into α axis. By injecting a high frequency voltage signal into d axis compared to the injection α The axis can provide better stability. Then, β The response current on the axis can be expressed as: , , in, V in and ω h are the amplitude and angular frequency of the high-frequency voltage respectively. Using traditional signal demodulation methods, such as Figure 5 Then, The magnitude can be expressed as: , Here, LPF(.) represents a low-pass filter. The magnitude depends on L d and L q Therefore, the saliency ratio of the FSPM motor can also be calculated by To reflect.

[0023] In order to study the saliency of FSPM motor, α The shaft is injected with a 8V-2kHz sinusoidal voltage. Then, the motor rotates at a speed of 50r / min. The traditional signal demodulation method can be used to obtain β Amplitude of shaft high frequency response current . The fundamental wave and second harmonic of can be obtained by bandpass filters corresponding to their respective frequencies. The fundamental wave contains the required rotor position information, but the second harmonic is a disturbance to the position observation. Figure 6 As shown in (a) in the figure, the amplitude of the fundamental wave is about 25mA, which is almost equal to the amplitude of the second harmonic. It is challenging to separate the fundamental wave from the ground. Low saliency and multiple saliency issues may cause the sensorless control based on reluctance saliency to not work properly. Figure 6 (b) is the experimental waveform after adding the short-circuit coil. The current amplitude of the fundamental wave is about 50mA, which is doubled compared with the previous amplitude without the short-circuit coil. However, the amplitude of the second harmonic does not increase significantly. Because the amplitude of the fundamental wave is almost twice that of the second harmonic, it is easy to The second harmonic is eliminated in the FSPM motor. This is also beneficial to solve the problem of multiple salient poles. It can be concluded that when the short-circuited coil is introduced in the FSPM motor by the proposed method, the fundamental wave of the current increases, while the second harmonic current remains almost unchanged. This is of great significance for sensorless control based on saliency ratio. This experiment shows that it is feasible to introduce magnetic saliency by adding a short-circuited coil.

[0024] Step 4: Determine the number of turns of the coil by comprehensively considering the loss and the reduction of inductance caused by the short-circuited coil through finite element simulation. The high frequency current is injected into d axis, and d Axis direction and Phase axis alignment. Figure 7 In (a), the amplitude of the high-frequency current in the short-circuited coil is shown. d Axis high frequency flux and It can be observed that the amplitude of the induced current and d The shaft flux increases with decreases with the increase of . d The reduction in axial flux indicates thatd The shaft equivalent inductance decreases. Then, the loss in the short-circuited coil is as follows: Figure 7 As shown in (b) in the figure, it can be observed that the loss increases with In addition, the loss is also acceptable. In this example, considering d The rate of change of the high-frequency flux amplitude of the shaft of increase and decrease, You can choose from a range of 5 to 15.

[0025] Step 5: To eliminate the harmonics caused by the multiple saliency problem from the position estimation, a second-order generalized integrator frequency-locked loop (SOGI-FLL) is applied. The structure of SOGI-FLL is shown in Figure 8 As shown. The input of SOGI-FLL can be expressed as: , Then, the transfer function of SOGI can be expressed as: , , in, is the center frequency. Obviously, is a bandpass filter type transfer function with a center frequency of At the same time, at the center frequency The transfer function at It can be equivalent to an integrator. The Bode diagram of SOGI is as follows Fig. 9 Therefore, SOGI can be obtained from the input And SOGI can build a The signals have the same amplitude but are 90° out of phase. In order to improve the dynamic performance of SOGI and make it frequency adaptive, a frequency-locked loop FLL is applied. At the same time, the feedforward frequency related to the reference speed is is added to the control loop to make the velocity estimation faster. When SOGI-FLL reaches steady state, its output can be expressed as: , , in, A is the amplitude. Then, the estimated position can be obtained through a phase-locked loop (PLL) .

[0026] Step 6: Use the estimated speed and position angle as feedback to implement position-free control of the FSPM motor. Fig.10is the structural block diagram of the entire control strategy. In order to verify the proposed position sensorless control strategy based on magnetic salient poles, the position sensorless control method without short-circuit coils and the position sensorless control method with short-circuit coils are compared. =50. First, you need to lead both ends of the short-circuit coil out of the motor. Then, use a connector to connect the short-circuit coil outside the motor. After that, apply The rotor field oriented control strategy is adopted, and the rotor position information required for control is provided by the position observer. Then, when the motor reaches a stable state, the short-circuit coil is disconnected. The specific experimental results are as follows Fig.11 As shown, the motor runs at a speed of 50r / min, Δ θ e is the error between the actual position and the estimated position. It can be observed that before the short-circuit coil is disconnected, the position error is within the range of ±0.1rad. However, after the short-circuit coil is disconnected, the position error will increase to -0.4rad. Therefore, it is feasible to improve positionless control by using magnetic saliency. Then, in order to study the steady-state performance of position sensorless control of FSPM motor based on magnetic saliency, an experiment was carried out when the motor was running at 50r / min. First, the three-phase current waveform is as follows Fig.12 As shown in (a) of Figure 1, it can be observed that the three-phase current waveform is symmetrical and sinusoidal. In addition, the high-frequency current signal is superimposed on the three-phase current, and due to the high-frequency voltage α On-axis injection, The pulsation of the phase current is greater than the pulsation of the other two phase currents. Then, the output quadrature signal of SOGI is as follows Fig.12 As shown in (b) in the figure. Since the FSPM motor has multiple salient poles, Contains many harmonics. After SOGI filtering, and The waveform of is highly sinusoidal, and the phase difference between the two is 90°. Fig.12 (c) in Figure 1 shows the comparison between the actual speed and its estimated speed. In steady state, the estimated speed tracks the actual speed very well, and the speed error between the actual speed and the estimated speed is within the range of ±3r / min. Finally, the comparison between the estimated rotor position and the actual rotor position is shown in Fig.12 As shown in (d), the estimated position is very close to the actual position. It can be observed that the maximum position error value is about 0.1rad. These experimental results can prove that the position sensorless control of the FSPM motor based on magnetic saliency can produce satisfactory steady-state performance. Finally, in order to verify the dynamic performance of the proposed position sensorless method, Fig.13(a) in Figure 1 shows the starting performance of the proposed sensorless method under rated load. Given a speed reference value of 50r / min, the motor can track the given speed value within 300ms. In the short time when the motor starts, the position error increases to -0.4rad. However, the position error converges quickly to near zero afterwards, and the position error remains within the range of ±0.1rad. Fig.13 (b) in Figure 1 shows the performance of the position sensorless approach when a step change in the speed reference occurs at rated load. The speed reference changes from 40r / min to 60r / min and then from 60r / min to 40r / min. It can be observed that the motor speed tracks the reference very well both in the acceleration and deceleration phases. In addition, the position error will increase during the acceleration and deceleration phases of the motor. However, when the motor enters a steady state, the error will converge to a range of ±0.1rad.

[0027] It should be understood that the above examples are only used to illustrate the present invention and are not used to limit the scope of the present invention. After reading the present invention, various equivalent modifications of the present invention made by those skilled in the art all fall within the scope defined by the claims attached to this application.

Claims

1. A position sensorless control method for FSPM motor based on magnetic saliency, characterized in that: The method comprises the following steps: Step 1: According to the vector magnetic circuit theory, a magnetic induction element - a short-circuit coil is added to the magnetic circuit to change the inductance; Step 2, arranging coils in the FSPM motor, and connecting the coils in reverse series in sequence, and then short-circuiting the entire coil to form a short-circuited coil; Step 3, in the stationary coordinate system α High-frequency pulse voltage is injected into the shaft; Step 4, using finite element software ANSYA, analyzing the relationship between the loss and flux after adding the short-circuit coil and the number of turns of the short-circuit coil to determine the value range of the number of turns of the short-circuit coil; Step 5: Sample the stationary coordinate system β The shaft current is extracted by signal demodulation method to obtain the high-frequency response current containing the position angle information, and then processed by the second-order generalized integrator SOGI-FLL with frequency-locked loop and the estimated position angle and speed information is obtained by phase-locked loop. Step 6: The motor control strategy adopts a rotor field oriented control method, and uses the estimated speed and position as feedback signals to replace the actual measured speed and position.

2. The method for controlling a FSPM motor without a position sensor based on magnetic saliency according to claim 1, characterized in that: The vector magnetic circuit theory and magnetic induction element in step 1, The magnetic circuit equation after introducing magnetic induction into the magnetic circuit is expressed as: ， Where: m represents the magnetic circuit, represents the magnetic induction of the magnetic circuit, represents the magnetic resistance of the magnetic circuit, represents the magnetic flux of the magnetic circuit, is the imaginary number symbol, represents the magnetomotive force of the magnetic circuit, is the angular frequency of the variable in the magnetic circuit; the magnetic induction is considered to be the reflection of the short-circuited coil in the magnetic circuit, so the magnetomotive force is written as ， In the formula, represents the number of turns of the short-circuited coil, Represents the current of the short-circuited coil, combining the above two equations to obtain: ， Then, define the complex inductance as ; Therefore, the new relationship between magnetic flux and current is expressed as: ， In the formula, Represents the magnetic flux. In order to more intuitively show the relationship between inductance and complex inductance, the inductance formula is Substituting into the above formula, we get: ， In the formula, Represents the inductance. Obviously, when When the complex inductance Equal to inductance ,when When the complex inductance The amplitude approaches 0, through the motor d Axis is a straight axis or q The direction of the axis or the cross axis increases the magnetic induction and can adjust the high frequency d Axis or q The size of the shaft inductance can meet the requirements of realizing the sensorless control algorithm based on high frequency injection. d Shaft Inductance L d No wait q Shaft inductance L q .

3. The method for controlling a FSPM motor without position sensor based on magnetic saliency according to claim 1, characterized in that: In the short-circuit coil in step 2, first, the winding function of the short-circuit coil is expressed as: ， Where: represents the number of pole pairs of the winding function, θ is the mechanical angle defined on the stator, with the subscript Indicates a short-circuited coil. It corresponds to The coefficient of the harmonic function of the secondary short-circuit coil winding. Similarly, the winding function of phase A is expressed as: ， in, represents the pole pair number of the A-phase winding function, It corresponds to The coefficient of the harmonic function of the A-phase winding is then obtained according to the three-phase distribution of the winding. Under the premise of ignoring the magnetic resistance and saturation of ferromagnetic materials, when the rotor is smooth and the stator core is slotted, the air gap permeability It is expressed as: ， Where: represents the DC component, It corresponds to The coefficient of the sub-harmonic permeance, Z s Indicates the number of stator poles. Similarly, when the stator is smooth and the rotor core is slotted, the air gap permeance It is expressed as: ， in, represents the DC component, It corresponds to The coefficient of the sub-harmonic permeance, Z r represents the number of rotor poles, θ r represents the position angle of the rotor. Then, when both the rotor and stator cores are slotted, the air gap permeance is as follows: ， Then, the inductance of the short-circuited coil is expressed as: ， in, and Respectively represent the stator inner diameter and the effective length of the lamination, the subscript Subscribed , b , c , Any replacement, represent The mutual inductance of the phase winding and the short-circuited coil; in order to change the FSPM motor by short-circuiting the coil d The magnetic induction of the shaft and the self-inductance of the short-circuited coil must be the same as the rotor position angle Unrelated, first of all, the self-inductance of the short-circuited coil It is expressed as: ， It is expressed as: ， Where: and They are respectively Second and The coefficients of the harmonic function of the secondary short-circuit coil winding are, according to the orthogonality of trigonometric functions, and The integral on the interval from 0 to 2π must satisfy the following conditions to be non-zero: ， Therefore, for a specific FSPM motor, this condition is used to select the number of pole pairs of the winding function of the short-circuit coil to meet and rotor position angle θ r Regardless, then according to the constraints q Mutual inductance of shaft winding and short-circuit coil Equal to 0 to design the connection method of the short-circuit coil.

4. The method for controlling a FSPM motor without position sensor based on magnetic saliency according to claim 1, characterized in that: The value range of the number of short-circuit coil turns in step 4 is as follows: adding a short-circuit coil to the FSPM motor will cause losses, so the selection of the number of short-circuit coil turns needs to consider the size of the losses. The finite element software ANSYS is used to simulate and analyze the specific FSPM motor, and a trade-off is made between the size of the magnetic saliency introduced by the short-circuit coil and the losses in the short-circuit coil, thereby determining the number of turns of the short-circuit coil.

5. The method for controlling a FSPM motor without position sensor based on magnetic saliency according to claim 1, characterized in that: In step 5, the estimated position angle and speed information are obtained through the phase-locked loop after SOGI-FLL processing. The input of SOGI-FLL is expressed as: ， Where: Represents a high-frequency current signal containing position angle information, represents the harmonic order, Representative is The magnitude of the secondary component, represents the electrical angle of the rotor, represents the initial phase angle, and the transfer function of SOGI is expressed as: ， ， Where: represent After the signal is filtered by SOGI-FLL, Yes and The corresponding quadrature signal, is the filter coefficient of SOGI-FLL, is the center frequency, is a bandpass filter type transfer function with a center frequency of , at the same time, at the center frequency The transfer function at Equivalent to an integrator; SOGI can be The harmonics are eliminated and SOGI can build a The signals have the same amplitude but a 90° phase difference. In order to improve the dynamic performance of SOGI and make it frequency adaptive, a frequency-locked loop (FLL) is applied. At the same time, the feedforward frequency related to the reference speed is added to the control loop to make the velocity estimation faster, when SOGI-FLL reaches steady state, its output is expressed as: ， ， in, A is the amplitude, and the estimated position is obtained through the phase-locked loop PLL .

6. The method for controlling a FSPM motor without position sensor based on magnetic saliency according to claim 1, characterized in that: The step 6 is to replace the actual measured values ​​with the estimated speed and position angle and bring them into the magnetic field oriented control to realize the position sensorless control of the system.

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