Method for identifying parameters of surface-mounted three-phase alternating-current permanent magnet synchronous motor on line

Abstract

The invention provides a method for on-line identification of parameters of a surface-mounted three-phase alternating-current permanent magnet synchronous motor, and the method comprises the steps: obtaining real-time currents on three phase lines of the motor, and converting the three-phase currents on the phase lines of the motor into currents under a two-phase alpha-beta-axis coordinate system; combining the current under the two-phase alpha-beta coordinate system with an electrical angle of a motor rotor, and converting the current into a current under a DQ-axis coordinate system; substituting the current under the DQ-axis coordinate system into a voltage equation under the motor DQ coordinate system; substituting the two-phase current under the alpha-beta coordinate system into a voltage equation with extended counter electromotive force of the motor under the alpha-beta coordinate system; simplifying a motor voltage equation under the motor DQ coordinate system; discretizing a voltage equation with extended counter electromotive force of the motor in an alpha-beta coordinate system according to a control period; and motor parameters are obtained under high-speed and low-speed conditions. According to the invention, no high-frequency specific pulse is injected, so that the interference to the operation of the motor is avoided.

Description

Technical Field

[0001] The present application relates to the field of motor control technology, and in particular 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 (PMSM): surface mounted permanent magnet synchronous motors and embedded permanent magnet synchronous motors. The motor parameters identified for surface mounted permanent magnet synchronous motors under rotor field oriented (FOC) vector control are: resistance , D-axis inductance and Q-axis inductance For surface mounted permanent magnet synchronous motors, the D-axis inductance and Q-axis inductance equal.

[0003] The current online parameter identification methods mainly include: model reference adaptive method (MARS), least squares method, high frequency injection method, identification using voltage equation under DQ axis, etc.

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

[0005] The present 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 online parameter identification methods.

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

[0007] Step 1: Use the current sensor 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 ; is the current component on the α-axis, is the current component on the β axis;

[0008] Step 2: The current in the two-phase αβ coordinate system , , 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 ;include:

[0019] The park transformation form is:

[0020] ;

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

[0022] Further, in step 3, the current in the DQ coordinate system is and , substituted into the voltage equation in the motor DQ coordinate system, including:

[0023] ;

[0024] in, Represents the motor D-axis voltage component in the DQ coordinate system at the current moment; Indicates the motor coil resistance; , 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 Differentiation with respect to time t; Indicates the electrical speed of the motor rotor at the current moment.

[0025] Furthermore, in step 4, the current in the two-phase αβ coordinate system is , Substitute into the voltage equation with extended back EMF of the motor in the αβ coordinate system, including:

[0026] ;

[0027] ;

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

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

[0030] ;

[0031] ;

[0032] Indicates the electrical speed of the motor rotor at the current moment; Represents the permanent magnet flux of the motor rotor; Indicates 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 .

[0033] Furthermore, in step five, the motor voltage equation in the motor DQ coordinate system is simplified, 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 follows:

[0036] ;

[0037] ;

[0038] , 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.

[0039] Further, in step seven, the back electromotive force of the motor in the αβ coordinate system under the α axis and the β axis is compared, and the voltage equation of the discretized motor with the extended back electromotive force in the αβ coordinate system is compared, and the two are combined to obtain the motor parameters in high speed and low speed conditions, including:

[0040] At low speed without weak magnetic control, =0; in high-speed weak magnetic control, 0; For surface mounted permanent magnet synchronous motor, the parameter characteristics are: ;

[0041] Dividing equation (4) by (5) and combining equations (7) and (8) yields:

[0042] ;

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

[0044] Indicates the electrical angle of the motor rotor The tangent function value of; when the field is weakened, 0, combined equations (6) and (9), we get:

[0045] ;

[0046] ;

[0047] When there is no field weakening control, = 0, and combining equations (6) and (9), we get:

[0048] ;

[0049] ;

[0050] 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 existing data from the motor control algorithm itself, does not increase the amount of data and its calculation process; and the calculation is conventional arithmetic and trigonometric function operations, which is relatively convenient; does not inject high-frequency specific pulses, is safe and reliable; does not use the Q-axis voltage equation in the DQ coordinate system, and avoids the interference of the motor magnetic flux. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Figure 1 This is the schematic diagram of the motor FOC vector control algorithm. DETAILED DESCRIPTION

[0054] In order to make the objectives, technical solutions and advantages of the present application clearer, the implementation methods of the present application will be further described in detail below with reference to the accompanying drawings.

[0055] The following first introduces the embodiments of the present application in conjunction with the accompanying drawings.

[0056] It is easy to obtain data, just by obtaining the data in the process of the motor rotor field oriented (FOC) vector control algorithm. The calculation is also based on the characteristic equation of the motor, which is more convenient. It does not inject high-frequency pulses to interfere with the system operation. It does not use the DQ coordinate system with magnetic flux. The voltage equation is used to avoid the influence of the flux parameters. The present invention is applicable to surface mounted permanent magnet synchronous motors, but not to embedded permanent magnet synchronous motors.

[0057] Step 1: Use the current sensor 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 ; is the current component on the α-axis, is the current component on the β axis;

[0058] The Clark transformation process is:

[0059] ;

[0060] , , It is the real-time current on the three phase lines of the motor, namely phase A, phase B, and phase C.

[0061] Step 2: The current in the two-phase αβ coordinate system , , 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;

[0062] The park transformation form is:

[0063] ;

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

[0065] Step 3: Convert the current in the DQ coordinate system and , substituted into the voltage equation in the motor DQ coordinate system, namely:

[0066] ;

[0067] in, Represents the motor D-axis voltage component in the DQ coordinate system at the current moment; Indicates the motor coil resistance; , 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 Differentiation with respect to time t; Indicates the electrical speed of the motor rotor at the current moment.

[0068] Step 4: Convert the current in the two-phase αβ coordinate system , Substitute it into the voltage equation of the motor with extended back electromotive force in the αβ coordinate system, that is:

[0069] ;

[0070] ;

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

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

[0073] ;

[0074] ;

[0075] Indicates the electrical speed of the motor rotor at the current moment; Represents the permanent magnet flux of the motor rotor; Indicates 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) yields:

[0086] ;

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

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

[0089] When the field is weakened, 0, combined equations (6) and (9), we get:

[0090] ;

[0091] ;

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

[0093] ;

[0094] ;

[0095] Equations (10), (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 obtained from Figure 1 The calculation process of the motor FOC vector control algorithm is obtained.

[0097] The present invention uses a motor model of a surface-mounted permanent magnet synchronous motor with an extended back electromotive force in a two-phase αβ coordinate system; at the same time, the D-axis voltage equation in the DQ coordinate system is used; 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 to identify the motor parameters. The electric speed and electric angle of the motor rotor of the present 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 motor rotor field orientation (FOC) vector control algorithm, without adding additional data volume and additional data calculation process; since the calculated data are all from the calculation process of the motor rotor field orientation (FOC) vector control algorithm itself, the motor identification method has significant usability.

[0098] The above-described embodiments of the present application 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 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 ; is the current component on the α-axis, is the current component on the β axis; Step 2: The current in the two-phase αβ coordinate system , , 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; Step 3: Convert the current in the DQ coordinate system and , substitute into the voltage equation in the motor DQ coordinate system; 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; 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 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.

2. The method according to claim 1, characterized in that Step 1: Use the current sensor 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: The Clark transformation process is: ； , , 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 in the two-phase αβ coordinate system , , 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 ;include: The park transformation form is: ； in, is the electrical angle of the motor rotor The sine function value of ; is the electrical angle of the motor rotor The cosine function value of .

4. The method according to claim 3, characterized in that Step 3: Convert the current in the DQ coordinate system and , substituted into the voltage equation in the motor DQ coordinate system, including: ； in, Represents the motor D-axis voltage component in the DQ coordinate system at the current moment; Indicates the motor coil resistance; , 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 Differentiation with respect to time t; 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 in the two-phase αβ coordinate system , Substitute into the voltage equation with extended back EMF of the motor in the αβ coordinate system, including: ； ； , They represent the voltage components of the motor voltage on the α-axis and the β-axis in the two-phase αβ coordinate system at the current moment respectively; , 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 Differentiation with respect to time t; Indicates the current β-axis current component Differentiation with respect to time t; , They represent the back electromotive force of the motor in the α-axis and β-axis in the αβ coordinate system respectively, and: ； ； Indicates the electrical speed of the motor rotor at the current moment; Represents the permanent magnet flux of the motor rotor; Indicates 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 .

6. The method according to claim 5, characterized in that Step 5: Simplify the motor voltage equation in the motor DQ coordinate system, including: 。 7. The method according to claim 6, characterized in that 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: ； ； , 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.

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

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