Adjustable flux motor sensorless control system and method based on flux observer

Abstract

The invention discloses an adjustable flux motor sensorless control system and method based on a flux observer. The system comprises an acquisition module, a Clark coordinate transformation module, a Park coordinate transformation module, a flux linkage observer, a phase-locked loop, a rotating speed loop, a q-axis current loop, a d-axis current loop, an iPark coordinate transformation module, an SVPWM module, an inverter module, a pulse counting module and a flux adjusting winding inverter. The method comprises the steps that the flux linkage error amount of the adjustable flux motor is calculated, the flux linkage estimation value of a flux linkage observer is compensated, and a flux linkage observer equation is listed and written. According to the method, the observation precision is improved, and the problems of large angle error caused by low-speed operation of the motor and phase delay caused by adoption of an inverse tangent function are solved; the calculation and compensation of inductance errors are omitted, and the influence on the system stability and the influence on the rotor position observation precision caused by the parameter change of inductance and the like due to the operation of the motor are reduced.

Description

Technical Field

[0001] The present invention relates to the field of motor control, and in particular to a position sensorless control system and method for an adjustable flux motor based on a flux linkage observer. Background Art

[0002] Permanent magnet synchronous motors (PMSMs) offer advantages such as simple structure, high power, high efficiency, and precise control, making them widely used in electric vehicles. However, because they use high-coercivity permanent magnets to achieve high power, the air gap magnetic field is difficult to adjust, resulting in a narrow constant power range and limited wide-speed operation. Traditional PMSMs apply a weakening current to the shaft, which, while somewhat widening the speed range, results in additional copper losses. Consequently, the concept of an adjustable flux motor (AVM) has been proposed, and various VMs based on different principles and structures have been developed, offering new options in the electric vehicle sector.

[0003] Adjustable flux motors can adjust the air gap flux by varying the permanent magnet excitation source. In addition to inheriting the advantages of traditional permanent magnet synchronous motors, adjustable flux motors also address the difficulties associated with conventional motors, such as the difficulty adjusting the permanent magnet field and the use of field-weakening control. During motor operation, the magnetic flux saturates to varying degrees, affecting the reluctance parameters and causing changes in the flux linkage parameters. To flexibly adjust the air gap magnetic field, pulsed current is applied to the motor to alter the magnetization state, and the flux can then adjust the magnetization level to achieve this goal.

[0004] When the magnetic circuit is fixed and the magnetic permeability is constant, the flux is proportional to the coil current. The flux observer control algorithm model is established based on the fixed inductance parameters. However, the operation of the motor will cause the inductance parameters to change, resulting in a large difference between the flux observation value and the actual value, causing the motor to operate unstable and even causing a failure of the flux adjustable drive control system. Summary of the Invention

[0005] Purpose of the invention: The purpose of the present invention is to provide a position sensorless control system and method for an adjustable flux motor based on a flux observer.

[0006] Technical solution: The position sensorless control system of the adjustable flux motor based on the flux observer of the present invention includes an acquisition module, a Clark coordinate transformation module, a Park coordinate transformation module, a flux observer, a phase-locked loop, a speed loop, a q-axis current loop, a d-axis current loop, an iPark coordinate transformation module, an SVPWM module, an inverter module, a pulse counting module and a magnetic winding inverter; the stator current i of the adjustable flux motor is obtained by the acquisition module. a ,i b The current command i in the two-phase stationary coordinate system is obtained by the Clark coordinate transformation module and ic αand i β ; The current i α and i β Input the voltage command u output by the iPark coordinate transformation module into the flux observer. α and u β Input into the flux observer, input the positive and negative pulses detected by the pulse counting module into the flux observer, and the flux observer outputs the flux and Magnetic flux observations and Input to the phase-locked loop and obtain the rotor position observation value through estimation and speed observations

[0007] Furthermore, the rotor position observation value Input to Park coordinate transformation module and SVPWM module, and obtain the speed observation value Feedback to the speed input terminal is compared and input to the speed loop, and then the current is obtained.

[0008] Furthermore, the Park coordinate transformation module outputs a current i d and i q , current i d With the d-axis current given reference value After comparison, it is input to the d-axis current loop and outputs the d-axis voltage Speed ​​loop output current With current i q After comparison, it is input to the q-axis current loop and outputs the q-axis voltage

[0009] Furthermore, the voltage and After the iPark coordinate transformation module, the voltage u in the two-phase stationary coordinate system is obtained α and u β , then input the voltage signal into the SVPWM module, output the PWM drive signal, and then drive the adjustable flux motor module in the acquisition module through the inverter module.

[0010] The present invention provides a position sensorless control method for an adjustable flux motor based on a flux observer, comprising the following steps:

[0011] (1) According to the pulse count module output pulses in the magnetic winding, where n1 is the number of positive pulses and n2 is the number of negative pulses, the flux linkage error of the adjustable flux motor is calculated to compensate the flux linkage estimation value of the flux linkage observer;

[0012] (2) Based on the model of the adjustable flux motor in a two-phase stationary coordinate system, the flux observer equation is written using the stator current through the flux / voltage equation;

[0013] (3) The observation value obtained by the nonlinear flux observer is compensated by the pulse counting module;

[0014] (4) Based on the flux observer, a phase-locked loop is used to extract the rotor position and speed information.

[0015] Furthermore, the step (1) includes:

[0016] Based on the adjustable flux motor model, a pulse signal is sent out through the magnetic winding inverter. The pulse counting module detects the positive pulse number as n1 and the negative pulse number as n2. In the counting pulse module of the flux observer in module 4, the positive pulse number n1 is counted as positive, and the pulse change is Δψ1. The negative pulse number n2 is recorded as negative, and the pulse change is Δψ2. The error value of the flux change caused by the parameter change of the adjustable flux motor is Δψ f =n1Δψ1-n2Δψ2.

[0017] Furthermore, the step (2) includes:

[0018] (2.1) The stator voltage equation of the adjustable flux motor in the two-phase stationary coordinate system is as follows:

[0019]

[0020] Among them, i α ,i β ,u α ,u β , e α , e β are the stator current, stator voltage and back electromotive force in the stationary coordinate system, L s , R s are the stator inductance and stator resistance respectively;

[0021] The flux equation in the two-phase stationary coordinate system is:

[0022]

[0023] Among them, ψ α and ψ β is the stator flux in the two-phase stationary coordinate system of the motor; fα and ψ fβ is the rotor flux in the two-phase stationary coordinate system, expressed as:

[0024]

[0025] Among them, ψf is the permanent magnet flux;

[0026] (2.2) According to the formula in step (2.1), the stator voltage equation in the stationary coordinate system is rewritten as the relationship between flux linkage and voltage, and the transformation is performed to obtain the following formula:

[0027]

[0028] From this formula, we can see that if two vectors are equal, then the corresponding elements in the vectors are equal and the modulus, that is, the 2-norm of the vector, is equal. Let the left side of the equation be:

[0029]

[0030] Similarly, for the right side of the equation:

[0031]

[0032] Combining the above three formulas, we can get the following formula:

[0033]

[0034] Then, a nonlinear flux observer is constructed according to the gradient descent method. The error of the observer is:

[0035]

[0036] in, is the stator flux observation error in the two-phase stationary coordinate system;

[0037] The nonlinear flux observer constructed based on the above information is as follows:

[0038]

[0039] Where λ is the gain coefficient of the nonlinear flux observer.

[0040] Furthermore, the step (3) includes:

[0041] The flux compensation module compensates the flux error value as follows:

[0042] Δψ f =n1Δψ1-n2Δψ2

[0043] In the stationary coordinate system, from step (2) we can know:

[0044]

[0045] The rotor flux compensation values ​​of the α-axis and β-axis in the stationary coordinate system by the flux compensation module are:

[0046]

[0047] According to the nonlinear flux observer equation, the output flux can be obtained as:

[0048]

[0049] After compensation, the flux linkage output by the flux linkage observer is:

[0050]

[0051] Furthermore, the step (4) includes:

[0052] The phase-locked loop system is used to estimate the required physical quantities and obtain the rotor angle. When, think If it holds, we can get the following relationship:

[0053]

[0054] in, is the estimated magnetic flux;

[0055] Position error ε n for:

[0056]

[0057] Furthermore, the angle of the rotor is an electrical angle.

[0058] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: the present invention calculates the error value of the flux change caused by parameter changes of the adjustable flux motor by pulse counting, and compensates the flux observation value with the calculated error value, thereby improving the observation accuracy; adopts a nonlinear flux observer, and extracts the speed and rotor position through a phase-locked loop, thereby avoiding the large angle error caused by low-speed operation of the motor and the phase delay problem caused by the use of the inverse tangent function; eliminates the calculation and compensation of the inductance error, reduces the impact of changes in parameters such as inductance caused by motor operation on system stability and the impact on the rotor position observation accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] Figure 1 It is a principle block diagram of the present invention;

[0060] Figure 2 The structure diagram of the flux observer based on pulse counting compensation nonlinear flux observer;

[0061] Figure 3 The structure diagram of the phase-locked loop in the position sensorless control method of the adjustable flux motor based on the flux observer;

[0062] Figure 4 This is the internal structure diagram of the flux compensation module;

[0063] Figure 5 This is the internal structure diagram of the nonlinear flux observer. DETAILED DESCRIPTION

[0064] The technical solution of the present invention will be further described below with reference to the accompanying drawings.

[0065] In the position sensorless vector control system of the adjustable flux motor, such as Figure 1 As shown, Clark coordinate transformation module 2, the expression is:

[0066]

[0067] The stator current i of the flux-adjustable motor can be acquired through acquisition module 1 a ,i b and i c The current command i in the two-phase stationary coordinate system is obtained through the Clark coordinate transformation module 2 α and i β . The current i α and i β The voltage command u output by the iPark coordinate transformation module 9 is input to the flux observer 4. α and u β Input into the flux observer 4, the positive and negative pulses detected by the pulse counting module 12 are input into the flux observer 4, and the flux observer 4 outputs the flux and Magnetic flux observations and Input to phase-locked loop 5, and obtain the rotor position observation value by estimation and speed observations

[0068] The rotor position observation value is obtained Input them into Park coordinate transformation module 3 and SVPWM module 10 respectively, and the speed observation value obtained is Feedback to the speed input terminal and input to the speed loop 6 after comparison, and then the current is obtained

[0069] The Park coordinate transformation module is:

[0070]

[0071] Output current i after Park coordinate transformation module 3 d and i q , current i d With the d-axis current given reference value After comparison, it is input to the d-axis current loop 8 and outputs the d-axis voltage Speed ​​loop 6 output current With current i q After comparison, it is input to the q-axis current loop and outputs the q-axis voltage

[0072] Voltage and After the iPark coordinate transformation module 9, the voltage u in the two-phase stationary coordinate system is obtained α and u β The voltage signal is then input into the SVPWM module 10, which outputs a PWM drive signal, which then drives the adjustable flux motor module of the acquisition module 1 through the inverter module 11.

[0073] like Figure 2 As shown, the method of combining pulse counting with observing the rotor position through the flux observer according to the present invention is different from the traditional method of using parameters to identify motor parameters by the flux observer. The pulse counting module 12 detects the number of positive and negative pulses to compensate for the flux, thereby improving the accuracy of the observation value.

[0074] The method for controlling an adjustable flux motor without position sensor based on a flux linkage observer comprises the following steps:

[0075] (1) According to the pulse count module output pulses in the magnetic winding, where n1 is the number of positive pulses and n2 is the number of negative pulses, the flux error of the adjustable flux motor is calculated and the flux estimation value of the flux observer is compensated; based on the adjustable flux motor model, such as Figure 4 As shown, the magnetic winding inverter 13 sends a pulse signal, the pulse counting module 12 detects the number of positive pulses as n1 and the number of negative pulses as n2, and the counting pulse module in the flux observer 4 counts the positive pulse number n1 as positive, and the pulse change is Δψ1, and the negative pulse number n2 is recorded as negative, and the pulse change is Δψ2. The error value of the flux change caused by the parameter change of the adjustable flux motor is Δψ f =n1Δψ1-n2Δψ2.

[0076] (2) According to the two-phase stationary coordinate system of the adjustable flux motor, based on the motor's flux and voltage equations, the stator current is obtained. The flux observer equation is calculated through the flux voltage equation. The specific implementation steps are as follows:

[0077] (2.1) The stator voltage equation of a variable flux permanent magnet motor in a two-phase stationary coordinate system is as follows:

[0078]

[0079] Where i α ,i β ,uα ,u β , e α , e β are the stator current, stator voltage and back electromotive force in the stationary coordinate system, L s , R s are the stator inductance and stator resistance respectively.

[0080] The flux equation in the two-phase stationary coordinate system is:

[0081]

[0082] Where, ψ α and ψ β is the stator flux in the two-phase stationary coordinate system of the motor; fα and ψ fβ is the rotor flux in the two-phase stationary coordinate system, which can be expressed as follows:

[0083]

[0084] Where, ψ f is the permanent magnet flux;

[0085] (2.2) According to the formula in step (2.1), the stator voltage equation in the stationary coordinate system is rewritten as the relationship between flux linkage and voltage, and the transformation is performed to obtain the following formula:

[0086]

[0087] From this formula, we can see that if two vectors are equal, then the corresponding elements in the vectors are equal and the modulus, that is, the 2-norm of the vector, is equal. Let the left side of the equation be:

[0088]

[0089] Similarly, for the right side of the equation:

[0090]

[0091] Combining the above three formulas, we can get the following formula:

[0092]

[0093] Then, a nonlinear flux observer is constructed according to the gradient descent method. The error of the observer is:

[0094]

[0095] Where, is the stator flux observation error in the two-phase stationary coordinate system.

[0096] like Figure 5 As shown, the nonlinear flux observer constructed according to the above information is as follows:

[0097]

[0098] Where λ is the gain coefficient of the nonlinear flux observer.

[0099] (3) According to Figure 2 It can be seen that the observation value obtained by the nonlinear flux observer is compensated by the pulse counting module, which is implemented in the following steps:

[0100] From step (1), it can be seen that the flux compensation module compensates the flux error value as follows:

[0101] Δψ f =n1Δψ1-n2Δψ2

[0102] In the stationary coordinate system, from step (2) we can know:

[0103]

[0104] Therefore, the rotor flux compensation values ​​of the flux compensation module for the α-axis and β-axis in the stationary coordinate system are:

[0105]

[0106] According to the nonlinear flux observer equation, the output flux can be obtained as:

[0107]

[0108] Therefore, after compensation, the flux linkage output by the flux linkage observer is:

[0109]

[0110] (4) A phase-locked loop system is used to estimate the required physical quantities and obtain the rotor angle information. Its structure diagram is as follows Figure 3 shown.

[0111] when When, think Established, based on Figure 3 The following relationship can be obtained:

[0112]

[0113] Where, is the estimated magnetic flux;

[0114] So the position error ε n for:

[0115]

[0116] All angles mentioned in the present invention are electrical angles.

Claims

1. A position sensorless control system for an adjustable flux motor based on a flux linkage observer, characterized in that: The invention comprises an acquisition module (1), a Clark coordinate transformation module (2), a Park coordinate transformation module (3), a flux observer (4), a phase-locked loop (5), a speed loop (6), a q-axis current loop (7), a d-axis current loop (8), an iPark coordinate transformation module (9), an SVPWM module (10), an inverter module (11), a pulse counting module (12) and a magnetic winding inverter (13); the stator current i of the magnetic flux motor can be adjusted by the acquisition module (1). a ,i b and i c The current command i in the two-phase stationary coordinate system is obtained through the Clark coordinate transformation module (2): α and i β ; The current i α and i β The voltage command u output by the iPark coordinate transformation module (9) is input to the flux observer (4). α and u β The positive and negative pulse numbers detected by the pulse counting module (12) are input into the flux observer (4), and the flux observer (4) outputs the flux and Magnetic Linkage Observation and Input to the phase-locked loop (5), and the rotor position observation value is obtained by estimation and speed observations 2. The position sensorless control system of an adjustable flux motor based on a flux observer according to claim 1 is characterized in that: The rotor position observation The speed observation value is input into the Park coordinate transformation module (3) and the SVPWM module (10) to obtain Feedback to the speed input terminal for comparison and input to the speed loop (6), and then the current is obtained.

3. The position sensorless control system of an adjustable flux motor based on a flux observer according to claim 1, characterized in that: The Park coordinate transformation module (3) outputs a current i d and i q , current i d With the d-axis current given reference value After comparison, it is input into the d-axis current loop (8) and outputs the d-axis voltage Speed ​​loop (6) output current With current i q After comparison, it is input into the q-axis current loop (7) and outputs the q-axis voltage 4. The position sensorless control system of an adjustable flux motor based on a flux observer according to claim 3 is characterized in that: The voltage and After the iPark coordinate transformation module (9), the voltage u in the two-phase stationary coordinate system is obtained. α and u β , and then inputs the voltage signal into the SVPWM module (10), outputs a PWM drive signal, and then drives the adjustable flux motor module in the acquisition module (1) through the inverter module (11).

5. A position sensorless control method for an adjustable flux motor based on a flux linkage observer, characterized in that: The steps include: (1) According to the pulses output by the pulse counting module in the magnetic flux regulating winding, where n1 is the number of positive pulses and n2 is the number of negative pulses, the flux linkage error of the adjustable flux motor is calculated to compensate the flux linkage estimation value of the flux linkage observer; (2) Based on the model of the adjustable flux motor in a two-phase stationary coordinate system, the flux observer equation is written out by passing the stator current through the flux / voltage equation; (3) The observation value obtained by the nonlinear flux observer is compensated by the pulse counting module; (4) Based on the flux observer, a phase-locked loop is used to extract the rotor position and speed information.

6. The method for controlling a position sensorless motor with adjustable flux based on a flux observer according to claim 5, characterized in that: The step (1) comprises: Based on the adjustable flux motor model, a pulse signal is sent through a magnetic winding inverter (13), and a pulse counting module (12) detects that the number of positive pulses is n1 and the number of negative pulses is n2. In the counting pulse module in the flux observer of module 4, the number of positive pulses is n1, which is counted as positive, and the pulse change is Δψ1, and the number of negative pulses is n2, which is counted as negative, and the pulse change is Δψ2. Therefore, the error value of the flux change caused by the parameter change of the adjustable flux motor is Δψ f =n1Δψ1-n2Δψ2.

7. The position sensorless control method of an adjustable flux motor based on a flux observer according to claim 5, characterized in that: The step (2) comprises: (2.1) The stator voltage equation of the adjustable flux motor in the two-phase stationary coordinate system is as follows: Among them, i α ,i β ,u α ,u β , e α , e β are the stator current, stator voltage and back electromotive force in the stationary coordinate system, L s , R s are stator inductance and stator resistance respectively; The flux equation in the two-phase stationary coordinate system is: Among them, ψ α and ψ β is the stator flux in the two-phase stationary coordinate system of the motor; ψ fα and ψ fβ is the rotor flux in the two-phase stationary coordinate system, expressed as: Among them, ψ f is the permanent magnet flux; (2.2) According to the formula in step (2.1), the stator voltage equation in the stationary coordinate system is rewritten into the relationship between flux linkage and voltage, and then transformed to obtain the following formula: From this formula, we can see that if two vectors are equal, then the corresponding elements in the vectors are equal and the modulus, that is, the 2-norm of the vector, is equal. Let the left side of the equation be: Similarly, for the right side of the equation: Combining the above three formulas, we can get the following formula: Then, the nonlinear flux observer is constructed according to the gradient descent method, and the error of the observer is: in, is the stator flux observation error in the two-phase stationary coordinate system; The nonlinear flux observer constructed according to the above information is as follows: Where λ is the gain coefficient of the nonlinear flux observer.

8. The position sensorless control method of an adjustable flux motor based on a flux observer according to claim 5, characterized in that: The step (3) comprises: The flux compensation module compensates the flux error value as follows: Dp f =n1Δψ1-n2Δψ2 In the stationary coordinate system, from step (2), we can know: The rotor flux compensation values ​​of the α-axis and the α-axis in the stationary coordinate system by the flux compensation module are: According to the nonlinear flux observer equation, the output flux can be obtained as: After compensation, the flux linkage finally output by the flux linkage observer is:

9. The method for controlling a position sensorless motor with adjustable flux based on a flux observer according to claim 5, characterized in that: The step (4) comprises: The phase-locked loop system is used to estimate the required physical quantity and obtain the rotor angle. When Established, we can get the following relationship: in, is the estimated magnetic flux; Position error ε n for:

10. The position sensorless control method of an adjustable flux motor based on a flux observer according to claim 9, characterized in that: The angle of the rotor is an electrical angle.

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