A method for online identifying parameters of a surface-mounted three-phase AC permanent magnet synchronous motor

Abstract

The present application provides a method for online identifying the parameters of a surface-mounted three-phase AC permanent magnet synchronous motor. The method includes: obtaining the real-time current on the three-phase lines of the motor, and transforming the three-phase current on the motor phase lines into the current in the two-phase αβ-axis coordinate system; combining the current in the two-phase αβ coordinate system with the electrical angle of the motor rotor and transforming it into the current in the DQ-axis coordinate system; substituting the current in the DQ-axis coordinate system into the voltage equation of the motor in the DQ coordinate system; substituting the current in the two-phase αβ coordinate system into the voltage equation with an extended back electromotive force of the motor in the αβ coordinate system; simplifying the motor voltage equation in the DQ coordinate system of the motor; discretizing the voltage equation with an extended back electromotive force of the motor in the αβ coordinate system according to the control period; obtaining the motor parameters in two cases of high speed and low speed. The present application does not inject high-frequency specific pulses, avoiding interference with the operation of the motor.

Description

Technical Field

[0001] This application relates to the technical field of motor control, and particularly relates to a method for online identification of parameters of a surface-mounted three-phase AC permanent magnet synchronous motor. Background Art

[0002] There are two types of three-phase AC permanent magnet synchronous motors (PMSMs): surface-mounted permanent magnet synchronous motors and embedded permanent magnet synchronous motors. Under the rotor field-oriented control (FOC) vector control mode of surface-mounted permanent magnet synchronous motors, the identified motor parameters are: resistance , D-axis inductance and Q-axis inductance . For surface-mounted permanent magnet synchronous motors, the D-axis inductance and the Q-axis inductance are equal.

[0003] The current online parameter identification methods mainly include: model reference adaptive method (MARS), least squares method, high-frequency injection method, identification using the voltage equation under the DQ axes, and so on.

[0004] However, these methods all have certain problems. For example, the model reference adaptive method (MARS) is computationally complex and has high requirements for the quality of data acquisition; the method of injecting high-frequency pulses will affect the actual operating state of the motor and increase noise, etc.; using the voltage equation in the DQ coordinate system for identification, and the motor magnetic flux is difficult to effectively identify, resulting in reduced accuracy or errors in the identification of other parameters. Summary of the Invention

[0005] This application provides a method for online identification of parameters of a surface-mounted three-phase AC permanent magnet synchronous motor, which can be used to solve the technical problem of low identification accuracy of the online parameter identification method.

[0006] This application provides a method for online identification of parameters of a surface-mounted three-phase AC permanent magnet synchronous motor, and the method includes:

[0007] Step 1, use a current sensor to obtain the real-time currents , , on the three-phase lines of the motor, and through the Clark transformation, transform the three-phase currents on the motor phase lines into currents and in the two-phase αβ coordinate system; is the current component on the α-axis, is the current component on the β-axis;

[0008] Step 2, the currents , , combined with the electrical angle of the motor rotor obtained from the motor angle sensor , after park transformation, it is transformed into the current in the DQ coordinate system and ;in, , They respectively represent the current components of the D-axis and Q-axis in the DQ coordinate system at the current moment;

[0009] Step 3: Convert the current in the DQ coordinate system and , substitute into the voltage equation in the motor DQ coordinate system;

[0010] Step 4: Convert the current in the two-phase αβ coordinate system , Substitute into the voltage equation with extended back EMF of the motor in the αβ coordinate system;

[0011] Step 5, simplify the motor voltage equation in the motor DQ coordinate system;

[0012] Step 6, the voltage equation of the motor with extended back electromotive force in the αβ coordinate system is discretized according to the control period;

[0013] Step seven, compare the back electromotive force of the motor in the α-axis and β-axis in the αβ coordinate system, and compare the voltage equation of the discretized motor with the extended back electromotive force in the αβ coordinate system, and combine the two to obtain the motor parameters in high-speed and low-speed situations.

[0014] Furthermore, in step 1, a current sensor is used to obtain the real-time current on the three-phase line of the motor. , , After Clark transformation, the three-phase current on the motor phase line is transformed into the current in the two-phase αβ coordinate system and ;include:

[0015] The Clark transformation process is:

[0016] ;

[0017] , , It is the real-time current on the three phase lines of the motor, namely phase A, phase B, and phase C.

[0018] Furthermore, in step 2, the current in the two-phase αβ coordinate system is , , combined with the electrical angle of the motor rotor obtained from the motor angle sensor , after Park transformation, it is transformed into the current in the DQ coordinate system and ; including:

[0019] The Park transformation form is:

[0020] ;

[0021] where, is the sine function value of the electrical angle of the motor rotor ; is the cosine function value of the electrical angle of the motor rotor ;

[0022] Furthermore, in step three, substitute the currents and in the DQ coordinate system into the voltage equation of the motor in the DQ coordinate system, including:

[0023] ;

[0024] where, represents the D-axis voltage component of the motor in the DQ coordinate system at the current moment; represents the resistance of the motor coil; , respectively represent the inductances of the motor in the D-axis and Q-axis in the DQ coordinate system; represents the current D-axis current component differentiated with respect to time t; represents the electrical speed of the motor rotor at the current moment.

[0025] Furthermore, in step four, substitute the currents , in the two-phase αβ coordinate system into the voltage equation of the motor in the αβ coordinate system with extended back electromotive force, including:

[0026] ;

[0027] ;

[0028] , respectively represent the voltage components of the motor voltage in the α-axis and β-axis in the two-phase αβ coordinate system at the current moment; , respectively represent the inductances of the motor in the α-axis and β-axis in the αβ coordinate system; represents the current α-axis current component differentiated with respect to time t; represents the current β-axis current component differentiated with respect to time t;

[0029] 、 respectively represent the back electromotive forces of the motor on the α-axis and β-axis in the αβ coordinate system, and:

[0030] ;

[0031] ;

[0032] represents the electrical speed of the motor rotor at the current moment; represents the magnetic flux of the permanent magnet of the motor rotor; represents the electrical angle of the motor rotor obtained from the motor angle sensor; represents the electrical angle of the motor rotor sine function value; represents the electrical angle of the motor rotor cosine function value.

[0033] Furthermore, in step five, simplify the motor voltage equation in the DQ coordinate system of the motor, including:

[0034] .

[0035] Furthermore, in step six, the voltage equation of the motor with extended back electromotive force in the αβ coordinate system is discretized according to the control period as:

[0036] ;

[0037] ;

[0038] 、 respectively represent the current components of the motor current on the α-axis and β-axis in the two-phase αβ coordinate system in the previous control period; represents the moment of the current control period; represents the moment of the previous control period; represents the recorded time difference between the two control times and .

[0039] Furthermore, in step seven, take the ratio of the back electromotive forces of the motor on the α-axis and β-axis in the αβ coordinate system, and take the ratio of the discretized voltage equation of the motor with extended back electromotive force in the αβ coordinate system. Combine the two, and obtain the motor parameters in two cases of high speed and low speed, including:

[0040] In the case of low-speed non-field-weakening control, = 0; in the case of high-speed field-weakening control, 0; For the surface-mounted permanent magnet synchronous motor, the parameter characteristics are as follows: ;

[0041] Dividing Equation (4) by (5), and combining Equations (7) and (8), we get:

[0042] ;

[0043] It can be seen from Equation (9) that the influence of the permanent magnet flux linkage of the motor rotor is eliminated.

[0044] represents the tangent function value of the electrical angle of the motor rotor; when weak magnetic control is applied, 0, combining Equations (6) and (9), we get:

[0045] ;

[0046] ;

[0047] When there is no weak magnetic control, = 0, combining Equations (6) and (9), we get:

[0048] ;

[0049] ;

[0050] The motor parameters include: resistance , D-axis inductance and Q-axis inductance .

[0051] The present invention provides a simple method for real-time identification of motor parameters, which helps to improve the control performance of the motor.

[0052] The present invention obtains the existing data from the motor control algorithm itself without adding new data volume and its calculation process; and the calculation is conventional arithmetic and trigonometric function operations, which is relatively convenient; no high-frequency specific pulses are injected, which is safe and reliable; the Q-axis voltage equation in the DQ coordinate system is not used, avoiding the interference of the motor magnetic flux. Description of the Drawings

[0053] Figure 1 is the schematic diagram of the motor FOC vector control algorithm. Detailed Embodiment

[0054] To make the purpose, technical solution and advantages of the present application clearer, the following will further describe the embodiments of the present application in detail with reference to the drawings.

[0055] First, the embodiments of the present application will be introduced below in conjunction with the accompanying drawings.

[0056] It is easy to obtain data, which can be achieved simply by acquiring data during the motor rotor field-oriented control (FOC) vector control algorithm. During the calculation, only the characteristic equation of the motor is combined, which is relatively convenient; no high-frequency pulses are injected to interfere with the system operation; and the voltage equation with flux linkage in the DQ coordinate system is not used, avoiding the influence of flux linkage parameters. The present invention is applicable to surface-mounted permanent magnet synchronous motors and not applicable to embedded permanent magnet synchronous motors. The present invention is applicable to surface-mounted permanent magnet synchronous motors and not applicable to embedded permanent magnet synchronous motors.

[0057] Step 1: Use a current sensor to obtain the real-time currents 、 、 on the three-phase lines of the motor. After Clark transformation, the three-phase currents on the motor phase lines are transformed into currents and in the two-phase αβ coordinate system; is the current component on the α-axis, is the current component on the β-axis;

[0058] The Clark transformation process is as follows:

[0059] ;

[0060] 、 、 are the real-time currents on the three-phase lines of the motor, namely, the A-phase, B-phase, and C-phase.

[0061] Step 2: Combine the currents 、 in the two-phase αβ coordinate system with the electrical angle of the motor rotor obtained from the motor angle sensor, and after Park transformation, transform them into currents and in the DQ coordinate system; where 、 respectively represent the current components on the D-axis and Q-axis in the DQ coordinate system at the current moment;

[0062] The Park transformation form is as follows:

[0063] ;

[0064] where is the sine function value of the electrical angle of the motor rotor; is the cosine function value of the electrical angle of the motor rotor.

[0065] Step 3: Substitute the currents in the DQ coordinate system, i.e., and , into the voltage equation of the motor in the DQ coordinate system, i.e.:

[0066] ;

[0067] where, represents the D-axis voltage component of the motor in the DQ coordinate system at the current moment; represents the resistance of the motor coil; , respectively represent the inductances of the motor in the D-axis and Q-axis in the DQ coordinate system; represents the current D-axis current component differentiated with respect to time t; represents the electrical speed of the motor rotor at the current moment.

[0068] Step 4: Substitute the currents in the two-phase αβ coordinate system, i.e., and , into the voltage equation of the motor in the αβ coordinate system with extended back electromotive force, i.e.:

[0069] ;

[0070] ;

[0071] , respectively represent the voltage components of the motor voltage in the α-axis and β-axis in the two-phase αβ coordinate system at the current moment; , respectively represent the inductances of the motor in the α-axis and β-axis in the αβ coordinate system; represents the current α-axis current component differentiated with respect to time t; represents the current β-axis current component differentiated with respect to time t;

[0072] , respectively represent the back electromotive forces of the motor in the α-axis and β-axis in the αβ coordinate system, and:

[0073] ;

[0074] ;

[0075] represents the electrical speed of the motor rotor at the current moment; represents the magnetic flux of the permanent magnet of the motor rotor; represents the electrical angle of the motor rotor obtained from the motor angle sensor; Indicates the electrical angle of the motor rotor The sine function value of ; Indicates the electrical angle of the motor rotor The cosine function value of .

[0076] Step 5: Simplify the motor voltage equation (1) in the motor DQ coordinate system:

[0077] .

[0078] Step 6: The voltage equation of the motor with extended back electromotive force in the αβ coordinate system is an equation about continuous time, while the control is periodic, and is discretized according to the control period as follows:

[0079] ;

[0080] ;

[0081] , , , , , , , , The meaning of is as stated above;

[0082] , They represent the current components of the motor current on the α and β axes in the two-phase αβ coordinate system in the previous control cycle respectively; Indicates the time of the current control cycle; Indicates the time of the previous control cycle; Indicates the control time before and after the record and time difference.

[0083] Step seven, compare the back electromotive force of the motor in the α-axis and β-axis in the αβ coordinate system, and compare the voltage equation of the discretized motor with the extended back electromotive force in the αβ coordinate system, and combine the two to obtain the motor parameters in high-speed and low-speed situations.

[0084] Since the motor has two control states at high and low speeds, it is in a weak magnetic field control state at high speed and in a non-weak magnetic field control state at low speed. =0; in high-speed weak magnetic control, 0; therefore, when performing parameter identification, it is also necessary to divide it into these two states. For surface-mounted permanent magnet synchronous motors, the parameter characteristics are: ;

[0085] Dividing Equation (4) by (5) and combining Equations (7) and (8), we get:

[0086] ;

[0087] representing the tangent function value of the electrical angle of the motor rotor ;

[0088] The meanings of other symbols are as described above.

[0089] When field-weakening control is applied, 0, combining Equations (6) and (9), we get:

[0090] ;

[0091] ;

[0092] When there is no field-weakening control, = 0, combining Equations (6) and (9), we get:

[0093] ;

[0094] ;

[0095] Equations (10) and (11), (12) and (13) are the identified motor parameters including: resistance , D-axis inductance and Q-axis inductance .

[0096] The data required for identification are all obtained from Figure 1 the calculation process of the motor FOC vector control algorithm in

[0097] The present invention uses a motor model with extended back electromotive force in the two-phase αβ coordinate system for a surface-mounted permanent magnet synchronous motor; at the same time, it uses the D-axis voltage equation in the DQ coordinate system; the motor voltage equation in the two-phase αβ coordinate system and the D-axis voltage equation in the DQ coordinate system are used together for motor parameter identification. The electrical speed and electrical angle of the motor rotor in this application are obtained from the position sensor attached to the motor rotor; the calculated data are all from the quantities in the process of the field-oriented control (FOC) vector control algorithm of the motor rotor, without adding additional data volume and the calculation process of additional data; since the calculated data are all from the calculation process of the field-oriented control (FOC) vector control algorithm of the motor rotor itself, this motor identification method has significant usability.

[0098] The embodiments of the present application described above do not constitute a limitation on the protection scope of the present application.

Claims

1. A method for online identification of surface mounted three-phase AC permanent magnet synchronous motor parameters, characterized in that: The method comprises: Step 1: Use the current sensor to obtain the real-time current i on the three-phase line of the motor A 、i B 、i C After Clark transformation, the three-phase current on the motor phase line is transformed into the current i in the two-phase αβ coordinate system α and i β ;i α is the current component on the α axis, i β is the current component on the β axis; Step 2: The current i in the two-phase αβ coordinate system is α 、i β , combined with the electrical angle θ of the motor rotor obtained from the motor angle sensor e , after park transformation, it is transformed into the current i in the DQ coordinate system d and i q ; where i d 、i q They respectively represent the current components of the D-axis and Q-axis in the DQ coordinate system at the current moment; Step 3: Convert the current i in the DQ coordinate system d and i q , substitute into the voltage equation in the motor DQ coordinate system; Step 4: Convert the current i in the two-phase αβ coordinate system α 、i β Substitute into the voltage equation with extended back EMF of the motor in the αβ coordinate system; Step 5, simplify the motor voltage equation in the motor DQ coordinate system; Step 6, the voltage equation of the motor with extended back electromotive force in the αβ coordinate system is discretized according to the control period; Step seven, compare the back electromotive force of the motor in the α-axis and the β-axis in the αβ coordinate system to obtain a first ratio, and compare the voltage equation of the discretized motor with the extended back electromotive force in the αβ coordinate system to obtain a second ratio, and the first ratio and the second ratio are combined to obtain the back electromotive force polar coordinate equation; combine the back electromotive force polar coordinate equation and the simplified motor voltage equation in the motor DQ coordinate system to obtain motor parameters in high-speed and low-speed conditions; Step 5: Simplify the motor voltage equation in the motor DQ coordinate system, including: u d =R*i d -ω e *L q *i q (6); Step 6: The voltage equation of the motor with extended back electromotive force in the αβ coordinate system is discretized according to the control period: i α(N-1) 、i β(N-1) They represent the current components of the motor current on the α and β axes in the two-phase αβ coordinate system in the previous control cycle; T represents the time of the current control cycle; T (N-1) Indicates the time of the previous control cycle; TT (N-1) Indicates the two control times T and T before and after the record (N-1) time difference.

2. The method according to claim 1, characterized in that Step 1: Use the current sensor to obtain the real-time current i on the three-phase line of the motor A 、i B 、i C After Clark transformation, the three-phase current on the motor phase line is transformed into the current i in the two-phase αβ coordinate system α and i β ; include: The Clark transformation process is: i A 、i B 、i C It is the real-time current on the three phase lines of the motor, namely phase A, phase B, and phase C.

3. The method according to claim 2, characterized in that Step 2: The current i in the two-phase αβ coordinate system is α 、i β , combined with the electrical angle θ of the motor rotor obtained from the motor angle sensor e , after park transformation, it is transformed into the current i in the DQ coordinate system d and i q ; include: The park transformation form is: Among them, Sin(θ e ) is the motor rotor electrical angle θ e The sine function value of Cos(θ e ) is the motor rotor electrical angle θ e The cosine function value of .

4. The method according to claim 3, characterized in that Step 3: Convert the current i in the DQ coordinate system d and i q , substituted into the voltage equation in the motor DQ coordinate system, including: Among them, u d represents the motor D-axis voltage component in the DQ coordinate system at the current moment; R represents the motor coil resistance; L d , L q They represent the inductance of the motor in the D-axis and Q-axis in the DQ coordinate system respectively; Indicates the current D-axis current component i d Differentiation with respect to time t; ω e Indicates the electrical speed of the motor rotor at the current moment.

5. The method according to claim 4, characterized in that Step 4: Convert the current i in the two-phase αβ coordinate system α 、i β Substitute into the voltage equation with extended back EMF of the motor in the αβ coordinate system, including: u α 、u β They represent the voltage components of the motor voltage on the α-axis and β-axis in the two-phase αβ coordinate system at the current moment; L α , L β They represent the inductance of the motor under the α-axis and β-axis in the αβ coordinate system respectively; Indicates the current α-axis current component i α Differentiation with respect to time t; Indicates the current β-axis current component i β Differentiation with respect to time t; E α 、E β They represent the back electromotive force of the motor in the α-axis and β-axis in the αβ coordinate system respectively, and: E α =-ω e *f f *Sin(θ e ) (4); E β =ω e *f f *Cos(θ e ) (5); ω e Indicates the electrical speed of the motor rotor at the current moment; φ f Represents the permanent magnet flux of the motor rotor; θ e Indicates the electrical angle of the motor rotor obtained from the motor angle sensor; Sin(θ e ) represents the motor rotor electrical angle θ e The sine function value of Cos(θ e ) represents the motor rotor electrical angle θ e The cosine function value of .

6. The method according to claim 5, characterized in that Step 7, comparing the back electromotive force of the motor in the α-axis and the β-axis in the αβ coordinate system to obtain a first ratio, and comparing the voltage equation of the discretized motor with the extended back electromotive force in the αβ coordinate system to obtain a second ratio, and the first ratio and the second ratio are combined to obtain the back electromotive force polar coordinate equation; Combine the back EMF polar coordinate equation and the simplified motor voltage equation in the motor DQ coordinate system to obtain motor parameters in high-speed and low-speed conditions, including: When there is no weak magnetic control at low speed, i d =0; in high-speed weak magnetic control, i d ≠0; For surface mounted permanent magnet synchronous motor, the parameter characteristics are: L d =L q =L α =L β ; Dividing equation (4) by (5) and combining equations (7) and (8) yields: tan(θ e ) represents the motor rotor electrical angle θ e The tangent function value of ; When the field is weakened, i d ≠0, combining equations (6) and (9), we get: When there is no field weakening control, i d =0, combining equations (6) and (9), we get: Motor parameters include: resistance R, D-axis inductance L d and Q-axis inductance L q .

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