Parameter identification method for permanent magnet synchronous motor

Abstract

The invention discloses a permanent magnet synchronous motor parameter identification method, which comprises the steps of S1, establishing a motor rotor coordinate system comprising a d axis and a q axis based on a permanent magnet synchronous motor, and obtaining a first dq axis voltage equation; when the motor is in a static state, obtaining a second dq-axis voltage equation according to the first dq-axis voltage equation; s2, a signal injection method is adopted to inject a square wave signal into a d axis, voltage and current of the d axis are sampled periodically, an identification equation of motor resistance is obtained, and a sampling period is recorded; s3, performing differential expansion on the second dq-axis voltage equation to obtain a differential expansion; and S4, performing different parameter identification processes for the non-salient pole machine or the salient pole machine according to the model of the motor, and finally obtaining two q-axis inductances and flux linkages respectively corresponding to the non-salient pole machine and the salient pole machine. According to the invention, different identification modes can be adopted according to the structure difference of the non-salient pole machine and the salient pole machine, and two q-axis inductances corresponding to the non-salient pole machine and the salient pole machine respectively can be obtained while the motor flux linkage is identified.

Description

Technical Field

[0001] The invention belongs to the technical field of motor parameter identification, and in particular relates to a permanent magnet synchronous motor parameter identification method. Background Art

[0002] Permanent magnet synchronous motors are widely used in the field of industrial control. In view of the various effects of changes in their internal parameters on the motor control performance, scholars at home and abroad have begun to conduct extensive research on motor parameter identification strategies.

[0003] The traditional ways to obtain motor parameters are mainly no-load and stalled tests. However, the motor parameters obtained by these two methods are relatively rough and cannot meet the requirements of most precise control algorithms. As the motor ages, it will age, depreciate and wear out, and its own parameters will be very different from the parameters when it leaves the factory.

[0004] The patent number "CN202111231736.6" discloses a method for identifying the parameters of a permanent magnet synchronous motor. The method determines the D and Q axis positions of the permanent magnet synchronous motor through a pre-positioning link, simplifies the parameter identification problem of the three-phase permanent magnet synchronous motor into the identification problem of the R and L series branches through coordinate transformation, and improves the identification accuracy through the least squares method. However, this identification method obtains the same identification results for both hidden pole machines and salient pole machines, resulting in low credibility. Summary of the invention

[0005] The purpose of the present invention is to provide a permanent magnet synchronous motor parameter identification method, which adopts different identification methods according to the structural differences between the hidden pole machine and the salient pole machine, and can obtain two q-axis inductances corresponding to the hidden pole machine and the salient pole machine respectively while identifying the motor flux.

[0006] In order to achieve the above-mentioned invention object, the technical solution adopted by the present invention is as follows:

[0007] A method for identifying parameters of a permanent magnet synchronous motor comprises the following steps of identifying the q-axis inductance and flux linkage of the permanent magnet synchronous motor:

[0008] Step S1. Establishing a motor rotor coordinate system including a d-axis and a q-axis based on a permanent magnet synchronous motor to obtain a first dq-axis voltage equation; when the motor is in a stationary state, obtaining a second dq-axis voltage equation according to the first dq-axis voltage equation;

[0009] Step S2. Inject a square wave signal into the d-axis using a signal injection method, periodically sample the voltage and current of the d-axis, obtain an identification equation of the motor resistance, and record the sampling period;

[0010] Step S3. Perform differential expansion on the second dq axis voltage equation according to the resistance of the motor and the sampling period to obtain a differential expansion;

[0011] Step S4. Determine whether the motor model is a hidden pole machine or a salient pole machine. If the motor is a salient pole machine, proceed to step S5. If the motor is a hidden pole machine, obtain the q-axis inductance of the hidden pole machine according to the differential expansion and proceed to step S5.

[0012] Step S5. When the motor is in steady-state operation, adjust the first dq axis voltage equation; then control the motor to obtain the equation of the motor rotor position angle; if the motor is a salient pole machine, proceed to step S6a; if the motor is a hidden pole machine, proceed to step S6b;

[0013] Step S6a. According to the adjusted first dq axis voltage equation and the motor rotor position angle equation, the d axis and q axis are sampled to identify the q axis inductance and flux linkage of the salient pole machine;

[0014] Step S6b. According to the adjusted first dq axis voltage equation and the motor rotor position angle equation, the d axis and the q axis are sampled to identify the magnetic flux of the hidden pole machine.

[0015] A method for identifying parameters of a permanent magnet synchronous motor of the present invention establishes a motor rotor coordinate system including a d-axis and a q-axis based on a permanent magnet synchronous motor, uses a signal injection method to identify the resistance and d-axis inductance of the motor when the motor is in a stationary state, and then performs IF open-loop control on the motor when the motor is in steady-state operation, and finally identifies the q-axis inductance and flux. In addition, the present invention adopts different identification methods according to the structural differences between a hidden pole machine and a salient pole machine, and can obtain two q-axis inductances corresponding to the hidden pole machine and the salient pole machine respectively while identifying the motor flux.

[0016] Preferably, the step S1 comprises:

[0017] Step S1.1. Establish a motor rotor coordinate system including the d-axis and the q-axis based on the permanent magnet synchronous motor, and obtain the first dq-axis voltage equation as follows:

[0018] ,

[0019] where u d is the d-axis voltage, R is the motor resistance, i d is the d-axis current and its differential term is L d is the d-axis inductance, ω e is the motor rotor speed, L q is the q-axis inductance, i q is the q-axis current and its differential term is ψ is the motor flux.

[0020] Preferably, the step S1 further comprises:

[0021] Step S1.2. When the motor is in a stationary state, the motor rotor speed is 0, the q-axis injection voltage is 0, and the q-axis feedback current is 0; the second dq-axis voltage equation is obtained according to the first dq-axis voltage equation as follows:

[0022]

[0023] Preferably, the step S2 comprises:

[0024] Step S2.1. Using the signal injection method, a square wave signal with a frequency of 400-600 Hz and an amplitude of 60-80 V is injected into the d-axis. At this time, the q-axis voltage is 0, and the motor rotor position angle θ is an arbitrary value;

[0025] Step S2.2. According to the adoption period T s By sampling the voltage and current of the d-axis, the identification equation of the motor resistance is obtained as follows:

[0026] ,

[0027] where u dmin is the minimum d-axis voltage, u dmax is the maximum voltage of the d-axis, i dmin is the minimum value of d-axis current, i dmax is the maximum value of d-axis current.

[0028] Preferably, step S3 comprises:

[0029] Step S3.1. According to the resistance and sampling period of the motor, the second dq axis voltage equation is differentially expanded to obtain the differential expansion as follows:

[0030]

[0031] , where n is the nth term of the difference terms, and n+1 is the n+1th term of the difference terms;

[0032] Step S3.2. Substitute the motor resistance R, sampling period Ts, and d-axis voltage u into the differential expansion d , d-axis current i d , we get the d-axis inductance L d .

[0033] Preferably, step S4 comprises:

[0034] Determine whether the motor model is a hidden pole machine or a salient pole machine. If the motor is a salient pole machine, proceed to step S5. If the motor is a hidden pole machine, obtain the q-axis inductance L of the hidden pole machine. q =L d , then go to step S5.

[0035] Preferably, step S5 comprises:

[0036] Step S5.1. When the motor is in steady-state operation, the d-axis current i d and its differential terms are all equal to 0, and the first dq axis voltage equation is adjusted to:

[0037]

[0038] Preferably, the step S5 further comprises:

[0039] Step S5.2. IF control of the motor: given a fixed open-loop speed ω e , the equation for the motor rotor position angle θ is as follows:

[0040] ,

[0041] Where t is the time taken by the motor to perform IF control;

[0042] Step S5.3. If the motor is a salient pole machine, proceed to step S6a; if the motor is a hidden pole machine, proceed to step S6b.

[0043] Preferably, step S6a comprises: sampling the d-axis voltage u according to the adjusted first dq-axis voltage equation and the motor rotor position angle equation d , d-axis current i d , q-axis voltage u q , the q-axis inductance and magnetic flux of the salient-pole machine are identified.

[0044] Preferably, step S6b. based on the adjusted first dq axis voltage equation and the motor rotor position angle equation, sample the d axis voltage u d , d-axis current i d , q-axis voltage u q , the magnetic flux of the hidden pole machine can be identified.

[0045] Beneficial effects:

[0046] A method for identifying parameters of a permanent magnet synchronous motor of the present invention establishes a motor rotor coordinate system including a d-axis and a q-axis based on a permanent magnet synchronous motor, uses a signal injection method to identify the resistance and d-axis inductance of the motor when the motor is in a stationary state, and then performs IF open-loop control on the motor when the motor is in steady-state operation, thereby identifying the q-axis inductance and flux. In addition, the present invention adopts different identification methods according to the structural differences between a hidden pole machine and a salient pole machine, and can obtain two q-axis inductances corresponding to the hidden pole machine and the salient pole machine respectively while identifying the motor flux. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1Shown is a general flow chart of a method for identifying parameters of a permanent magnet synchronous motor;

[0048] Figure 2 Shown is a first sub-flow chart of a method for identifying parameters of a permanent magnet synchronous motor;

[0049] Figure 3 Shown is a second sub-flow chart of a method for identifying parameters of a permanent magnet synchronous motor;

[0050] Figure 4 The third sub-flow chart of a method for identifying parameters of a permanent magnet synchronous motor is shown;

[0051] Figure 5 The fourth sub-flow chart of a method for identifying parameters of a permanent magnet synchronous motor is shown. DETAILED DESCRIPTION

[0052] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the specific implementation methods of the present invention will be described below with reference to the accompanying drawings. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings and other implementation methods can be obtained based on these drawings without creative work.

[0053] The technical solution of the present invention is described in detail below with specific embodiments.

[0054] Example

[0055] like Figures 1 to 5 As shown, a method for identifying parameters of a permanent magnet synchronous motor in this embodiment includes the following steps of identifying the q-axis inductance and flux linkage of the permanent magnet synchronous motor:

[0056] Step S1. Establishing a motor rotor coordinate system including a d-axis and a q-axis based on a permanent magnet synchronous motor to obtain a first dq-axis voltage equation; when the motor is in a stationary state, obtaining a second dq-axis voltage equation according to the first dq-axis voltage equation;

[0057] Step S2. Inject a square wave signal into the d-axis using a signal injection method, periodically sample the voltage and current of the d-axis, obtain an identification equation of the motor resistance, and record the sampling period;

[0058] Step S3. Perform differential expansion on the second dq axis voltage equation according to the resistance of the motor and the sampling period to obtain a differential expansion;

[0059] Step S4. Determine whether the motor model is a hidden pole machine or a salient pole machine. If the motor is a salient pole machine, proceed to step S5. If the motor is a hidden pole machine, obtain the q-axis inductance of the hidden pole machine according to the differential expansion and proceed to step S5.

[0060] Step S5. When the motor is in steady-state operation, adjust the first dq axis voltage equation; then control the motor to obtain the equation of the motor rotor position angle; if the motor is a salient pole machine, proceed to step S6a; if the motor is a hidden pole machine, proceed to step S6b;

[0061] Step S6a. According to the adjusted first dq axis voltage equation and the motor rotor position angle equation, the d axis and q axis are sampled to identify the q axis inductance and flux linkage of the salient pole machine;

[0062] Step S6b. According to the adjusted first dq axis voltage equation and the motor rotor position angle equation, the d axis and the q axis are sampled to identify the magnetic flux of the hidden pole machine.

[0063] Preferably, step S1 comprises:

[0064] Step S1.1. Establish a motor rotor coordinate system including the d-axis and the q-axis based on the permanent magnet synchronous motor, and obtain the first dq-axis voltage equation as follows:

[0065] ,

[0066] where u d is the d-axis voltage, R is the motor resistance, i d is the d-axis current and its differential term is L d is the d-axis inductance, ω e is the motor rotor speed, L q is the q-axis inductance, i q is the q-axis current and its differential term is ψ is the motor flux.

[0067] Preferably, step S1 further includes:

[0068] Step S1.2. When the motor is in a stationary state, the motor rotor speed is 0, the q-axis injection voltage is 0, and the q-axis feedback current is 0; the second dq-axis voltage equation is obtained according to the first dq-axis voltage equation as follows:

[0069]

[0070] Preferably, step S2 comprises:

[0071] Step S2.1. Using the signal injection method, a square wave signal with a frequency of 400-600 Hz and an amplitude of 60-80 V is injected into the d-axis. At this time, the q-axis voltage is 0, and the motor rotor position angle θ is an arbitrary value;

[0072] Step S2.2. According to the voltage and current of the d-axis sampled at the period Ts, the identification equation of the motor resistance is obtained as follows:

[0073] ,

[0074] where u dmin is the minimum d-axis voltage, u dmax is the maximum voltage of the d-axis, i dmin is the minimum value of d-axis current, i dmax is the maximum value of d-axis current.

[0075] Preferably, step S3 comprises:

[0076] Step S3.1. According to the resistance and sampling period of the motor, the second dq axis voltage equation is differentially expanded to obtain the differential expansion as follows:

[0077] ,

[0078] Where n is the nth term of the difference terms, and n+1 is the n+1th term of the difference terms;

[0079] Step S3.2. Substitute the motor resistance R, sampling period Ts, and d-axis voltage u into the differential expansion d , d-axis current i d , we get the d-axis inductance L d .

[0080] Preferably, step S4 comprises:

[0081] Determine whether the motor model is a hidden pole machine or a salient pole machine. If the motor is a salient pole machine, proceed to step S5. If the motor is a hidden pole machine, obtain the q-axis inductance L of the hidden pole machine. q =L d , then go to step S5.

[0082] Preferably, step S5 comprises:

[0083] Step S5.1. When the motor is in steady-state operation, the d-axis current i d and its differential terms are all equal to 0, and the first dq axis voltage equation is adjusted to:

[0084]

[0085] Preferably, step S5 further includes:

[0086] Step S5.2. IF control of the motor: given a fixed open-loop speed ω e , the equation for the motor rotor position angle θ is as follows:

[0087] ,

[0088] Where t is the time taken by the motor to perform IF control;

[0089] Step S5.3. If the motor is a salient pole machine, proceed to step S6a; if the motor is a hidden pole machine, proceed to step S6b.

[0090] Preferably, step S6a comprises: sampling the d-axis voltage u according to the adjusted first dq-axis voltage equation and the motor rotor position angle equation d , d-axis current i d , q-axis voltage u q , the q-axis inductance and magnetic flux of the salient-pole machine are identified.

[0091] Preferably, step S6b. based on the adjusted first dq axis voltage equation and the motor rotor position angle equation, sample the d axis voltage u d , d-axis current i d , q-axis voltage u q , the magnetic flux of the hidden pole machine can be identified.

[0092] Specifically, in step S1.2 of this embodiment, when the motor is in a stationary state, the motor rotor speed is 0, the q-axis injection voltage is 0, and the q-axis feedback current is 0.

[0093] Specifically, in step S2.1 of this embodiment, a signal injection method is used to inject a square wave signal with a frequency of 500 Hz and an amplitude of 70 V into the d-axis. At this time, the q-axis voltage is 0, and the motor rotor position angle θ is an arbitrary value.

[0094] Furthermore, in step S2.1 of this embodiment, a signal injection method is used to inject a square wave signal of the d-axis, that is, the input voltage U d , thus obtaining the d-axis feedback current i d And q-axis feedback current i q .

[0095] Furthermore, by obtaining the d-axis feedback current i d And q-axis feedback current i q , substituting into the identification equation and differential expansion of the motor resistance, the resistance R and d-axis inductance L of the motor can be calculated respectively. d .

[0096] Specifically, in step S2.2 of this embodiment, the addition of the maximum value and the minimum value of the d-axis voltage and the addition of the maximum value and the minimum value of the d-axis current are performed to obtain an average value. Other common methods can also be used to obtain the average value, which will not be described in detail here.

[0097] Specifically, in steps S2 to S4 of this embodiment, the motor parameters are identified by the signal injection method before the motor is started to obtain the resistance R and d-axis inductance L of the motor. d This method of injecting square waves is stable and reliable.

[0098] Specifically, in step S5.1 of this embodiment, the motor is controlled according to FOC operation, and a control strategy in which the d-axis current is equal to 0 is adopted, so that the motor is operated in a steady state.

[0099] Furthermore, the differential term of the d-axis current is equal to 0 when the motor is running in a steady state.

[0100] Specifically, step 5 of this embodiment controls the motor by using the IF switch control and the fixed frequency control, so that the parameter identification result can be accurate.

[0101] Furthermore, in step S6a, the IF switch control of the motor can obtain a three-phase UVW waveform diagram, and the q-axis inductance L of the salient pole machine can be determined based on the waveform diagram. q size.

[0102] Specifically, a permanent magnet synchronous motor parameter identification method of this embodiment establishes a motor rotor coordinate system including a d-axis and a q-axis based on a permanent magnet synchronous motor, uses a signal injection method to identify the resistance and d-axis inductance of the motor when the motor is in a stationary state, and then performs IF open-loop control on the motor when the motor is in steady-state operation, and finally identifies the q-axis inductance and flux. In addition, the present invention adopts different identification methods according to the structural differences between the hidden pole machine and the salient pole machine, and can obtain two q-axis inductances corresponding to the hidden pole machine and the salient pole machine respectively while identifying the motor flux.

[0103] The above is a detailed description of an embodiment of a method for identifying parameters of a permanent magnet synchronous motor provided by the present invention. This article uses specific examples to illustrate the principles and implementation methods of the present invention, and the description of the above embodiments is only used to help understand the core idea of ​​the present invention. It should be pointed out that for ordinary technicians in this technical field, without departing from the principles of the present invention, the present invention can also be improved and modified, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A method for identifying parameters of a permanent magnet synchronous motor, characterized in that: The steps of identifying the q-axis inductance and flux linkage of a permanent magnet synchronous motor are as follows: Step S1. Establishing a motor rotor coordinate system including a d-axis and a q-axis based on a permanent magnet synchronous motor to obtain a first dq-axis voltage equation; when the motor is in a stationary state, obtaining a second dq-axis voltage equation according to the first dq-axis voltage equation; Step S2. Inject a square wave signal into the d-axis using a signal injection method, periodically sample the voltage and current of the d-axis, obtain an identification equation of the motor resistance, and record the sampling period; Step S3. Perform differential expansion on the second dq axis voltage equation according to the resistance of the motor and the sampling period to obtain a differential expansion; Step S4. Determine whether the motor model is a hidden pole machine or a salient pole machine. If the motor is a salient pole machine, proceed to step S5. If the motor is a hidden pole machine, obtain the q-axis inductance of the hidden pole machine according to the differential expansion and proceed to step S5. Step S5. When the motor is in steady-state operation, adjust the first dq axis voltage equation; then control the motor to obtain the equation of the motor rotor position angle; if the motor is a salient pole machine, proceed to step S6a; if the motor is a hidden pole machine, proceed to step S6b; Step S6a. According to the adjusted first dq axis voltage equation and the motor rotor position angle equation, the d axis and q axis are sampled to identify the q axis inductance and flux linkage of the salient pole machine; Step S6b. According to the adjusted first dq axis voltage equation and the motor rotor position angle equation, the d axis and the q axis are sampled to identify the magnetic flux of the hidden pole machine.

2. The method for identifying parameters of a permanent magnet synchronous motor according to claim 1, characterized in that: The step S1 comprises: Step S1.

1. Establish a motor rotor coordinate system including the d-axis and the q-axis based on the permanent magnet synchronous motor, and obtain the first dq-axis voltage equation as follows: ， where u d is the d-axis voltage, R is the motor resistance, i d is the d-axis current and its differential term is L d is the d-axis inductance, ω e is the motor rotor speed, L q is the q-axis inductance, i q is the q-axis current and its differential term is ψ is the motor flux.

3. The method for identifying parameters of a permanent magnet synchronous motor according to claim 2, characterized in that: The step S1 further comprises: Step S1.

2. When the motor is in a stationary state, the second dq axis voltage equation is obtained according to the first dq axis voltage equation as follows:

4. The method for identifying parameters of a permanent magnet synchronous motor according to claim 3, characterized in that: The step S2 comprises: Step S2.

1. Using the signal injection method, inject a square wave signal with a frequency of 400-600 Hz and an amplitude of 60-80 V into the d-axis; Step S2.

2. According to the voltage and current of the d-axis sampled at the period Ts, the identification equation of the motor resistance is obtained as follows: ， where u dmin is the minimum d-axis voltage, u dmax is the maximum voltage of the d-axis, i dmin is the minimum value of d-axis current, i dmax is the maximum value of d-axis current.

5. The method for identifying parameters of a permanent magnet synchronous motor according to claim 4, characterized in that: The step S3 comprises: Step S3.

1. According to the resistance and sampling period of the motor, the second dq axis voltage equation is differentially expanded to obtain the differential expansion as follows: ， Where n is the nth term of the difference terms, and n+1 is the n+1th term of the difference terms; Step S3.

2. Substitute the motor resistance R, sampling period Ts, and d-axis voltage u into the differential expansion d , d-axis current i d , we get the d-axis inductance L d .

6. The method for identifying parameters of a permanent magnet synchronous motor according to claim 5, characterized in that: The step S4 includes: determining whether the motor model is a hidden pole machine or a salient pole machine. If the motor is determined to be a salient pole machine, proceeding to step S5; if the motor is determined to be a hidden pole machine, obtaining the q-axis inductance L of the hidden pole machine. q =L d , then go to step S5.

7. The method for identifying parameters of a permanent magnet synchronous motor according to claim 6, characterized in that: The step S5 comprises: Step S5.

1. When the motor is in steady-state operation, adjust the first dq axis voltage equation to:

8. The method for identifying parameters of a permanent magnet synchronous motor according to claim 7, characterized in that: The step S5 further comprises: Step S5.

2. IF control of the motor: given a fixed open-loop speed ω e , the equation for the motor rotor position angle θ is as follows: ， Where t is the time taken by the motor to perform IF control; Step S5.

3. If the motor is a salient pole machine, proceed to step S6a; if the motor is a hidden pole machine, proceed to step S6b.

9. The method for identifying parameters of a permanent magnet synchronous motor according to claim 8, characterized in that: Step S6a includes: sampling the d-axis voltage u according to the adjusted first dq-axis voltage equation and the motor rotor position angle equation d , d-axis current i d , q-axis voltage u q , the q-axis inductance and magnetic flux of the salient-pole machine are identified.

10. The method for identifying parameters of a permanent magnet synchronous motor according to claim 8, characterized in that: Step S6b. Sample the d-axis voltage u according to the adjusted first dq-axis voltage equation and the motor rotor position angle equation. d , d-axis current i d , q-axis voltage u q , the magnetic flux of the hidden pole machine can be identified.

Images