A method for obtaining dq-0 axis inductance parameters of an open-winding permanent magnet synchronous motor

Abstract

The present invention discloses a method for obtaining d-q-0 axis inductance parameters of an open-winding permanent magnet synchronous motor, comprising the following steps: S101, short-circuiting U, V, and W terminals of the open-winding permanent magnet synchronous motor; S102, passing low-voltage direct current between phases A and B of the motor to lock the angle between the rotor reference axis and the stator A-phase axis. After the angle between the rotor reference axis and the stator A-phase axis is locked, cutting off the power supply; S103, measuring the phase inductance of the stator three-phase winding; S104, measuring the line inductance of the stator three-phase winding; S105, calculating the mutual inductance between the three-phase stator winding; S106, obtaining a relationship between the three-phase winding flux linkage and the d-q-0 axis inductance based on a mathematical model of the open-winding permanent magnet synchronous motor; and S107, applying coordinate transformation theory to derive an expression for the d-q-0 axis inductance represented by the phase inductance and the line inductance, and substituting the expression into the measured data to obtain the d-q-0 axis inductance.

Description

Technical Field

[0001] The present invention relates to the field of motor control technology, and in particular to a method for obtaining dq-0 axis inductance parameters of an open-winding permanent magnet synchronous motor. Background Art

[0002] The open-winding permanent magnet synchronous motor (PMSM), a new type of motor system that has been widely studied in recent years, opens the neutral point of the three-phase stator winding connected in a star configuration without changing the original motor's electromagnetic design or mechanical structure. Power inverters are connected to the beginning and end of the stator winding, and two sets of inverters are used to drive and control the motor. This dual-converter topology increases the number of vectors controlled from 8 to 64, generating more voltage levels on the phase windings and providing more flexible control. The control effect is closely related to the accuracy of the motor's dq-0 axis inductance parameter measurement.

[0003] The main methods for measuring the inductance parameters of synchronous motors include time constant measurement, extreme value method, frozen permeability finite element calculation, and load measurement. The time constant measurement method measures the current step response to obtain the time constant while creating balanced three-phase current conditions. However, accurately obtaining any rotor rotation angle is difficult. The extreme value method slowly rotates the motor rotor and calculates the maximum and minimum values. However, artificially rotating the motor slowly can result in large measurement errors. The frozen permeability finite element calculation method performs a saturated finite element calculation on the motor load, then selects and saves the permeability of each element. Linear finite element calculations are then performed for both the permanent magnet excitation and the stator current excitation. However, this method is computationally intensive and requires high external equipment. Load measurement records the voltage and current waveforms, rotor position, and load angle over one or two time periods. The inductance value is calculated based on the fundamental current. However, the inverter output contains a large number of harmonics, and the obtained voltage and current contain a high level of harmonic content, which significantly affects measurement accuracy.

[0004] The aforementioned methods often struggle to balance accuracy and convenience, and most focus on measuring the DC-axis inductance parameters of traditional permanent magnet synchronous motors. However, they rarely address the measurement of the zero-axis inductance of new motor systems, such as open-winding permanent magnet synchronous motors. The drive control of open-winding permanent magnet synchronous motors, particularly those employing a dual-inverter topology with a common DC bus, creates a zero-sequence current path that significantly increases system losses. Therefore, zero-sequence current suppression is essential. However, most zero-sequence current suppression schemes rely heavily on the zero-axis inductance parameter value. Summary of the Invention

[0005] The technical problem to be solved by the present invention is how to accurately obtain the d-axis inductance L of the open-winding permanent magnet synchronous motor. d , q-axis inductance L q and the parameter value of the zero-axis inductance L0.

[0006] To solve the above technical problems, the technical solution adopted by the present invention is: a method for obtaining the dq-0 axis inductance parameters of an open-winding permanent magnet synchronous motor, comprising the following steps:

[0007] Step S101, short-circuit the U, V, and W terminals of the open-winding permanent magnet synchronous motor, with the short-circuit point defined as N;

[0008] Step S102: Pass low-voltage direct current between phases A and B of the motor to lock the angle between the rotor reference axis and the stator phase A axis. After the angle between the rotor reference axis and the stator phase A axis is locked, cut off the power supply.

[0009] Step S103, measuring the phase inductance of the stator three-phase winding;

[0010] Step S104, measuring the line inductance of the stator three-phase winding;

[0011] Step S105, calculating the mutual inductance between the three phases of the stator winding;

[0012] Step S106: Based on the mathematical model of the open-winding permanent magnet synchronous motor, obtain the relationship between the three-phase winding flux linkage and the dq-0 axis inductance;

[0013] Step S107 : Apply coordinate transformation theory to derive a dq-0 axis inductance expression represented by phase inductance and line inductance, and substitute the measured data into the expression to obtain the dq-0 axis inductance.

[0014] A further improvement of the technical solution of the present invention is that: in step S102, the motor stator phase A is connected to the positive terminal of the DC power supply, and the phase B is connected to the negative terminal of the DC power supply; the motor is rotated so that the angle between the rotor reference axis and the stator phase A axis is constant at θ rA =-30°.

[0015] The further improvement of the technical solution of the present invention is that the process of measuring the phase inductance value of the three phases of the stator in step S103 is as follows: using an inductance measuring instrument, one end of the measuring terminal is connected to the three phase winding ends A, B, and C of the motor stator, and the other end of the measuring terminal is connected to the short circuit point N, and the three phase inductance L of the motor AN, BN, and CN is measured. aa 、L bb 、L cc .

[0016] The further improvement of the technical solution of the present invention is that the process of measuring the line inductance of the three-phase stator in step S104 is: using an inductance measuring instrument, connecting the two ends of the measuring terminal to any two phase ends of the three-phase winding A, B, and C of the motor stator, and measuring the line inductance L of the motor AB, BC, and CA. ab 、L bc 、L ca.

[0017] A further improvement of the technical solution of the present invention is that the calculation formula of the mutual inductance value between the three-phase stator windings in step S105 is as follows:

[0018]

[0019] Among them, M ab 、M ba is the mutual inductance between motors AB; M bc 、M cb is the mutual inductance between motors BC; M ca 、M ac is the mutual inductance value between the motors CA.

[0020] A further improvement of the technical solution of the present invention is that the specific process of step S106 is:

[0021] The stator flux equation in the dq-0 coordinate system is shown as follows:

[0022]

[0023] in, They are the motor d, q, 0-axis magnetic flux, i d 、i q , i0 are the motor d, q, 0 axis currents respectively, It is the magnetic flux generated by the interaction between the permanent magnet poles and the stator;

[0024] The inverse transformation matrix in the coordinate system with the d axis as the reference [T abc ] -1 :

[0025]

[0026] Among them, θ r is the angle between the d-axis and the stator A-phase reference axis;

[0027] The relationship between the magnetic flux in the dq-0 coordinate system and the magnetic flux in the three-phase stationary coordinate system is obtained:

[0028]

[0029] They are the A, B, and C phase flux of the motor stator respectively.

[0030] A further improvement of the technical solution of the present invention is that the specific process of step S107 is as follows:

[0031] Stator flux equation in three-phase stationary coordinate system:

[0032]

[0033] θ is the angle between the motor rotor magnetic pole axis and the A-phase stator winding axis;

[0034] Applying coordinate transformation theory, substitute θ = θ r =θ rA =-30°, derive the d-axis inductance L of the open-winding permanent magnet synchronous motor d , q-axis inductance L q And the parameter calculation expression of zero-axis inductance L0:

[0035]

[0036] Substituting the measured data, the dq-0 axis inductance value can be obtained.

[0037] Due to the adoption of the above technical solution, the technical advancements achieved by the present invention are:

[0038] The present invention realizes the d-axis inductance L of the split-winding permanent magnet synchronous motor. d , q-axis inductance L q The zero-axis inductance L0 parameters are accurately obtained. First, the structural advantages of the open-winding motor are utilized to short-circuit one end of the stator winding to create a balanced condition; a low-voltage DC current is passed between the AB phases of the motor, and the angle between the rotor reference axis and the stator A phase axis is locked according to the relationship between the phase voltage and the line voltage; under this condition, the phase inductance and line inductance of the three-phase stator are measured, and the mutual inductance between the three-phase windings is calculated; then, based on the mathematical model of the open-winding permanent magnet synchronous motor, the magnetic flux equations in the abc coordinate system and the dq-0 coordinate system are written respectively; with the d-axis as the reference axis, the coordinate transformation of the three-phase current of the stator is performed, and the i a 、i b 、i c Replace i in the dq-0 flux equation d 、i q , i0; calculate the d-axis inductance L through magnetic flux analysis and conversion d , q-axis inductance L q This method balances accuracy and convenience, utilizing the structural advantages of open-winding motors and requiring minimal external experimental equipment. It has a strong theoretical basis and can accurately obtain the zero-axis inductance for open-winding permanent magnet synchronous motor drive control, especially for drive modes using a common DC bus dual-inverter topology. This helps improve the suppression of zero-sequence current and motor control accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 It is an open-winding permanent magnet synchronous motor model;

[0040] Figure 2 is a flow chart of an embodiment;

[0041] Figure 3 The embodiments of the present invention are based on the two-phase and three-phase stator windings of the d-axis. DETAILED DESCRIPTION

[0042] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. The described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0043] The invention is based on the situation that the parameters of the split-winding permanent magnet synchronous motor are completely unknown and the inductance of the motor dq-0 axis is calculated by utilizing the criterion of equal flux linkage before and after coordinate transformation.

[0044] Figure 2 This is a flow chart of an embodiment of a method for obtaining parameters of an open-winding permanent magnet synchronous motor according to the present invention. As shown in the figure, the method includes:

[0045] Step 101: short-circuit the U, V, and W terminals of the open-winding permanent magnet synchronous motor.

[0046] In this embodiment, according to Figure 1 In the open-winding permanent magnet synchronous motor model, the U, V, and W terminals of the open-winding permanent magnet synchronous motor are short-circuited, and the short-circuit point is defined as N.

[0047] Step 102: Pass low-voltage direct current between phases A and B of the motor to lock the angle between the rotor reference axis and the stator phase A axis.

[0048] In this embodiment, a programmable DC power supply is used to input 10V DC between the two phases A and B of the motor. The motor stator phase A is connected to the positive terminal of the DC power supply, and the phase B is connected to the negative terminal of the DC power supply. The motor rotates a small angle so that the angle between the rotor reference axis and the stator phase A axis is constant at θ. rA =-30°.

[0049] Step 103: Measure the phase inductance of the three-phase stator winding.

[0050] In this embodiment, after the angle between the rotor reference axis and the stator A phase axis is locked, the power is cut off; using an inductance meter, one end of the measuring terminal is connected to the A, B, and C three-phase winding terminals of the motor stator, and the other end of the measuring terminal is connected to the short-circuit point N, and the three-phase inductance L of the motor AN, BN, and CN is measured. aa 、L bb 、L cc ;

[0051] Step 104: Measure the line inductance of the stator three-phase winding.

[0052] In this embodiment, after the angle between the rotor reference axis and the stator A phase axis is locked, the power is cut off; using an inductance meter, the two ends of the measuring terminals are connected to any two phase ends of the A, B, and C three-phase windings of the motor stator, and the line inductance L of the motor AB, BC, and CA is measured. ab 、L bc 、L ca .

[0053] Step 105: Calculate the mutual inductance between the three phases of the stator winding.

[0054] Get the phase inductance L of the stator three-phase winding aa 、L bb 、L cc , line inductance L ab 、L bc 、L ca Substitute into formula (1) to obtain the mutual inductance between the three-phase stator windings.

[0055]

[0056] Among them, M ab 、M ba is the mutual inductance between motors AB; M bc 、M cb is the mutual inductance between motors BC; M ca 、M ac is the mutual inductance value between the motors CA.

[0057] Step 106: Based on the mathematical model of the open-winding permanent magnet synchronous motor, obtain the relationship between the three-phase winding flux and the dq-0 axis inductance.

[0058] The stator flux equation expression in the dq-0 coordinate system is:

[0059]

[0060] in, They are the motor d, q, 0-axis magnetic flux, i d 、i q , i0 are the motor d, q, 0 axis currents respectively, It is the magnetic flux generated by the interaction between the permanent magnet poles and the stator;

[0061] in accordance with Figure 3 , the inverse transformation matrix [T abc ] -1 :

[0062]

[0063] Among them, θ r is the included angle between the d-axis and the stator A-phase reference axis.

[0064] Obtain the relationship between the magnetic flux in the dq-0 coordinate system and the magnetic flux in the three-phase stationary coordinate system:

[0065]

[0066] They are the magnetic flux of phases A, B and C of the motor stator respectively.

[0067] Step 107: Apply coordinate transformation theory to derive the dq-0 axis inductance expression represented by phase inductance and line inductance. Substitute the measured data into the dq-0 axis inductance to obtain

[0068] In this embodiment, the stator flux equation in the three-phase stationary coordinate system is expressed as follows:

[0069]

[0070] θ is the angle between the motor rotor magnetic pole axis and the A-phase stator winding axis.

[0071] The stator A phase flux equation in the three-phase stationary coordinate system is obtained:

[0072]

[0073] The d-axis defined here coincides with the rotor axis and θ=θ r , set θ = θ rA =-30° Substituting into formula (6), the stator A phase flux equation, with known parameters including only self-inductance and mutual inductance, is:

[0074]

[0075] Combining equations (2) and (4) yields the relationship between the dq-0 inductance and the stator A phase flux:

[0076]

[0077] in accordance with Figure 3 , the transformation matrix T in the coordinate system with the d axis as the reference abc :

[0078]

[0079] The relationship between the current in the dq-0 coordinate system and the current in the three-phase stationary coordinate system is obtained:

[0080]

[0081] Substituting formula (10) into formula (8) yields:

[0082]

[0083] θ r =θ rA =-30° is substituted into formula (11) and simplified and merged to obtain the unknown parameters in the three-phase stationary coordinate system, which only include L d 、L q , stator A phase flux equation of L0:

[0084]

[0085] Comparing the coefficient equations of formula (7) and formula (12), we get the calculation equation:

[0086]

[0087] Combining equation (1) with equation (13), we can obtain the calculation expression of the dq-0 inductance parameter:

[0088]

[0089] Substitute the known measurement parameters into the above formula: phase inductance L aa 、L bb 、L cc , line inductance L ab 、L bc 、L ca , the d-axis inductance L of the open-winding permanent magnet synchronous motor can be calculated d , q-axis inductance L q And the zero-axis inductance L0 parameter value.

[0090] Existing methods for measuring the inductance parameters of permanent magnet synchronous motors (PMSMs) often struggle to balance accuracy and convenience. Most methods focus on measuring the DC-axis inductance parameters of traditional PMSMs, while less research is needed on measuring the zero-axis inductance of new motor systems using open-winding PMSMs. The drive control of open-winding PMSMs, particularly those using a common DC bus dual-inverter topology, creates a zero-sequence current path that significantly increases system losses, necessitating zero-sequence current suppression. However, most zero-sequence current suppression schemes rely heavily on the zero-axis inductance parameter value. The proposed parameter acquisition method leverages the structural advantages of open-winding motors to accurately and conveniently acquire the dq-0-axis inductance parameters of the motor, effectively improving the control effectiveness of various control technologies for open-winding PMSMs.

[0091] The present invention realizes the d-axis inductance L of the split-winding permanent magnet synchronous motor. d , q-axis inductance L qThe zero-axis inductance L0 parameters are accurately obtained. First, the structural advantages of the open-winding motor are utilized to short-circuit one end of the stator winding to create a balanced condition; a low-voltage DC current is passed between the AB phases of the motor, and the angle between the rotor reference axis and the stator A phase axis is locked according to the relationship between the phase voltage and the line voltage; under this condition, the phase inductance and line inductance of the three-phase stator are measured, and the mutual inductance between the three-phase windings is calculated; then, based on the mathematical model of the open-winding permanent magnet synchronous motor, the magnetic flux equations in the abc coordinate system and the dq-0 coordinate system are written respectively; with the d-axis as the reference axis, the coordinate transformation of the three-phase current of the stator is performed, and the i a 、i b 、i c Replace i in the dq-0 flux equation d 、i q , i0; calculate the d-axis inductance L through magnetic flux analysis and conversion d , q-axis inductance L q This method combines accuracy and convenience, has low requirements for peripheral experimental equipment, and is supported by a strong theoretical basis. For the drive control of open-winding permanent magnet synchronous motors, especially for the drive mode using a common DC bus dual-inverter topology, it can accurately obtain the zero-axis inductance, which helps to improve the suppression effect of zero-sequence current and the control accuracy of the motor.

Claims

1. A method for obtaining the dq-0 axis inductance parameters of an open-winding permanent magnet synchronous motor, characterized by: The steps include: Step S101, short-circuit the U, V, and W terminals of the open-winding permanent magnet synchronous motor, with the short-circuit point defined as N; Step S102: Pass low-voltage direct current between phases A and B of the motor to lock the angle between the rotor reference axis and the stator phase A axis. After the angle between the rotor reference axis and the stator phase A axis is locked, cut off the power supply. Step S103, measuring the phase inductance of the stator three-phase winding; Step S104, measuring the line inductance of the stator three-phase winding; Step S105, calculating the mutual inductance between the three phases of the stator winding; Step S106: Based on the mathematical model of the open-winding permanent magnet synchronous motor, the relationship between the three-phase winding flux and the dq-0 axis inductance is obtained. The stator flux equation in the dq-0 coordinate system is shown as follows: in, They are the motor d, q, 0-axis magnetic flux, i d 、i q , i0 are the motor d, q, 0 axis currents respectively, It is the magnetic flux generated by the interaction between the permanent magnet poles and the stator; The relationship between the magnetic flux in the dq-0 coordinate system and the magnetic flux in the three-phase stationary coordinate system is: They are the magnetic flux of phases A, B and C of the motor stator respectively; Step S107: Apply coordinate transformation theory to derive the dq-0 axis inductance expression represented by the phase inductance and the line inductance. Substitute the measured data into the dq-0 axis inductance to obtain the dq-0 axis inductance. The specific process is as follows: Stator flux equation in three-phase stationary coordinate system: θ is the angle between the motor rotor magnetic pole axis and the A-phase stator winding axis; Applying coordinate transformation theory, substitute θ = θ r =θ rA =-30°, derive the d-axis inductance L of the open-winding permanent magnet synchronous motor d , q-axis inductance L q And the parameter calculation expression of zero-axis inductance L0: Substituting the measured data, the dq-0 axis inductance value can be obtained.

2. The method for obtaining the dq-0 axis inductance parameters of an open-winding permanent magnet synchronous motor according to claim 1, wherein: In step S102, the motor stator phase A is connected to the positive terminal of the DC power supply, and the phase B is connected to the negative terminal of the DC power supply; the motor is rotated so that the angle between the rotor reference axis and the stator phase A axis is constant at θ rA =-30°.

3. The method for obtaining the dq-0 axis inductance parameters of an open-winding permanent magnet synchronous motor according to claim 2, wherein: The process of measuring the phase inductance of the stator three-phase winding in step S103 is as follows: using an inductance measuring instrument, connect one end of the measuring terminal to the three-phase winding terminals A, B, and C of the motor stator, and connect the other end of the measuring terminal to the short-circuit point N, and measure the three-phase inductance L of the motor AN, BN, and CN. aa 、L bb 、L cc .

4. The method for obtaining the dq-0 axis inductance parameters of an open-winding permanent magnet synchronous motor according to claim 3, characterized in that: The process of measuring the line inductance of the stator three-phase winding in step S104 is as follows: using an inductance measuring instrument, connecting the two ends of the measuring terminals to any two phase ends of the three-phase windings A, B, and C of the motor stator, and measuring the line inductance L of the motor AB, BC, and CA. ab 、L bc 、L ca .

5. The method for obtaining dq-0 axis inductance parameters of an open-winding permanent magnet synchronous motor according to claim 4, characterized in that: The calculation formula of the mutual inductance value between the three-phase stator windings in step S105 is as follows: Among them, M ab 、M ba is the mutual inductance between motors AB; M bc 、M cb is the mutual inductance between motors BC; M ca 、M ac is the mutual inductance value between the motors CA.

6. The method for obtaining dq-0 axis inductance parameters of an open-winding permanent magnet synchronous motor according to claim 5, characterized in that: The inverse transformation matrix [T abc ] -1 : Among them, θ r is the included angle between the d-axis and the stator A-phase reference axis.

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