WO2024120487A1

WO2024120487A1 - Calibration method for performance of permanent magnet synchronous motor

Info

Publication number: WO2024120487A1
Application number: PCT/CN2023/137120
Authority: WO
Inventors: 马永志; 刘朝辉; 邹广才; 原诚寅
Original assignee: 北京国家新能源汽车技术创新中心有限公司
Priority date: 2022-12-09
Filing date: 2023-12-07
Publication date: 2024-06-13
Also published as: CN116224058A

Abstract

The present invention relates to the technical field of electric motors. Specifically disclosed is a calibration method for the performance of a permanent magnet synchronous motor. The specific steps of the calibration method comprise: S1, mounting on a rack an electric motor to be subjected to calibration, wherein the electric motor to be subjected to calibration is connected to an electric-motor controller, and the electric-motor controller is connected to a high-voltage direct-current power source; S2, at a low rotation speed n1, measuring the torque and voltage of the electric motor by using all currents I and all phase angles θ one by one, so as to obtain the maximum torque T1 at each current in a low-speed non-weak magnetic region and a corresponding phase angle θ1; S3, performing processing by means of an interpolation method, so as to obtain an optimal phase angle θ2 at each current at different rotation speeds n2 in a high-speed weak magnetic region and a corresponding torque T2; S4, measuring no-load torques T3 at different rotation speeds in a full-rotation-speed region; and S5, calculating mechanical torques T at different rotation speeds in the full-rotation-speed region, and performing collation to obtain a table, so as to complete calibration. By means of the calibration method, an optimal performance parameter of an electric motor to be subjected to calibration in a full-rotation-speed region is found, the whole calibration process is safe and reliable, the steps are fast and convenient, and the accuracy is high.

Description

A method for calibrating the performance of permanent magnet synchronous motor

Technical Field

The present invention relates to the technical field of motors, and in particular to a method for calibrating the performance of a permanent magnet synchronous motor.

Background technique

With the increasing popularity of new energy vehicles, permanent magnet synchronous motors are increasingly widely used in new energy vehicles due to their high efficiency, small size, and high power density. In order to achieve accurate and safe control of permanent magnet synchronous motors, it is necessary to calibrate the performance of permanent magnet synchronous motors.

In order to ensure that the permanent magnet synchronous motor can have the best performance and can operate safely within the entire operating range, it is necessary to use a test bench to test it. During the test, the current of the specified working point within the entire speed and torque operating range of the motor needs to be accurately calibrated. The calibration method of the performance of the permanent magnet synchronous motor currently mostly adopts the method of full-scan test calibration on the bench, that is, within the full speed range, the bench scans each speed, each current, and each current phase angle test, but this workload is large, and requires the calibration personnel to be highly professional and experienced, because high-speed calibration is more dangerous, and it is easy to cause dangerous conditions such as out-of-control running, communication interruption, and excessive temperature rise and burning. Others use the motor simulation data provided by the motor engineer for calibration. This method is convenient and fast, but the simulated data is not accurate enough, and it will ignore the saturation effect, end effect, and the actual material performance deviation, manufacturing consistency and other problems. Therefore, this method is not accurate enough and sometimes has a large deviation.

Therefore, a safer, more reliable, more convenient, faster and more accurate calibration method is needed to calibrate the performance of permanent magnet synchronous motors.

Summary of the invention

In order to overcome the problems of complicated steps, large workload, danger and inaccurate calibration in the prior art permanent magnet synchronous motor performance calibration method, the present invention provides a new permanent magnet synchronous motor performance calibration method. Machine performance calibration method.

In order to solve the above technical problems, the present invention adopts the following technical solutions:

A method for calibrating the performance of a permanent magnet synchronous motor, the method comprising the following steps:

S1: The motor to be calibrated is installed on a test bench, the motor to be calibrated is connected to a motor controller, and the motor controller is connected to a high-voltage DC power supply;

S2: At low speed n ₁ , the motor torque and voltage are tested one by one with full current I and full phase angle θ, and the maximum torque T ₁ and corresponding phase angle θ ₁ of each current in the low speed non-weakening magnetic zone are obtained;

S3: Obtain the optimal phase angle θ ₂ and the corresponding torque T ₂ of different currents at different speeds n ₂ in the high-speed weak magnetic zone by interpolation method;

S4: Test the no-load torque T ₃ at different speeds in the full speed range, i.e. the no-load loss torque;

S5: Calculate the mechanical torque T at different speeds in the full speed range and organize it into a table to complete the calibration.

Furthermore, the range of the full current I is 0-peak current, the range of the full phase angle θ is 0-90°, the current I increases by one tenth of the peak current each time starting from 0, and the phase angle θ increases by 5° each time starting from 0, that is, there are multiple groups of corresponding current I and phase angle θ.

Furthermore, according to the formula I _d =I·Cos(90°+θ), I _q =I·Sin(90°+θ), the current I _d and the current I _q corresponding to each group of currents I are calculated.

Furthermore, the specific steps of the one-by-one testing in step 2 are: testing the motor to be calibrated once under each set of corresponding current I and phase angle θ, and recording the torque, d-axis voltage U _d1 , and q-axis voltage U _q1 each time after the motor to be calibrated runs stably, thereby obtaining multiple sets of data.

Preferably, a two-dimensional torque table is obtained by tabulating multiple groups of data obtained by the test, and the maximum torque T ₁ and the corresponding phase angle θ ₁ of each current in the low-speed non-weakening magnetic region are obtained by comparison and sorting.

Due to the different ranges of the permanent magnet synchronous motor in the constant torque area (low speed non-weak magnetic area) At the speed, the same current generates the same torque, so the maximum torque T ₁ and the corresponding phase angle θ ₁ of each current in the low-speed non-weakening magnetic zone can be obtained through the test of low speed n ₁ .

Furthermore, the step 3 also includes:

S31: Calculate the direct-axis flux Ψ _d and the quadrature-axis flux Ψ _q corresponding to the full current I (0-peak current) and the full phase angle θ (0-90°) at low speed n _1. The calculation formula for this step is:

Get multiple sets of Ψ _d and Ψ _q ,

Among them, R is the stator winding resistance, measured by a resistance meter, _ωe is the electrical angular velocity, which is related to the rotational speed, and n is the rotational speed.

S32: Calculate the d-axis voltage U _d2 and q-axis voltage U _q2 corresponding to different high speeds n ₂ at full current I (0-peak current) and full phase angle θ (0-90°). The calculation formula for this step is:

U _d2 =R·I _d -ω _e ·ψ _q , U _q2 =R·I _q +ω _e ·ψ _d , and multiple groups of U _d2 and U _q2 corresponding to different speeds n _2, different currents I ₂ and phase angles θ are obtained;

S33: In the high-speed weak magnetic field area, calculate the phase voltage U _s corresponding to the full current I (0-peak current) and the full phase angle θ (0-90°) at different high speeds n _2. The calculation formula for this step is:

U _s = sqrt(U _d2 ·U _d2 +U _q2 ·U _q2 ), we get multiple groups of U _s ,

Among them, sqrt is the square root;

S34: In the high-speed weak magnetic field area, different high speeds n ₂ at full current I (0-peak current), use the interpolation method to find the value that satisfies The phase angle θ ₂ value is the optimal phase angle θ ₂ at different high speeds and different currents.

Among them, U _dc is the direct current high voltage, which is a performance parameter of the motor system, and K is the weak magnetic coefficient, which is a control parameter of the motor system;

S35: According to the optimal phase angle θ ₂ at different high speeds n ₂ and different currents, the two-dimensional torque table in S2 is combined with the interpolation method to obtain the corresponding torque T ₂ .

Furthermore, the value of the mechanical torque T at different speeds at full speed in step 4 is the difference between the optimal torque and the no-load torque _T3 .

It can be seen that in the calibration process, the performance of the motor to be calibrated is tested at a low speed in the low-speed weak magnetic field area, and the optimal performance parameters are found out based on the test data; for the high-speed weak magnetic field area, the optimal performance parameters corresponding to different high speeds are obtained through calculation and interpolation; finally, the optimal performance parameters of the motor to be calibrated in the full speed range are completed, and the calibration of the motor performance is completed.

The present invention has at least the following beneficial effects:

1. A permanent magnet synchronous motor performance calibration method provided by the present invention tests the performance parameters of the motor to be calibrated at full current and full phase angle at a low speed, and obtains the optimal performance parameters of the motor to be calibrated in the low-speed non-weakening magnetic zone, without the need to calibrate each speed in the low-speed non-weakening magnetic zone;

2. A permanent magnet synchronous motor performance calibration method provided by the present invention obtains the optimal performance parameters at different high speeds in the high-speed weak magnetic field area by calculation and interpolation based on the relevant data tested at low speed, thereby avoiding the performance parameters of the motor to be calibrated at high speed, making the calibration process safer, more reliable and faster;

3. The present invention provides a method for calibrating the performance of a permanent magnet synchronous motor, which makes the optimal torque finally measured more accurate by testing the no-load torque at different speeds.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a flow chart of a method for calibrating the performance of a permanent magnet synchronous motor provided by the present invention.

Detailed ways

In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution 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. Obviously, the described embodiments are 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 creative work are within the scope of protection of the present invention.

Embodiment 1

The present invention discloses a method for calibrating the performance of a permanent magnet synchronous motor, which specifically comprises the following steps:

S1: Install the motor to be calibrated on the test bench, connect the motor to be calibrated with the motor controller, connect the motor controller with the high-voltage DC power supply, and pass the current I with a phase angle of θ into the motor to be calibrated;

S21: the current I starts from 0 and gradually increases from 40A to a peak current of 400A, and is set to 11 values; the current phase angle θ starts from 0 and gradually increases from 5° to 90°, and is set to 19 values, that is, the current I and the phase angle θ are set to 209 groups in total;

S22: Control the speed of the motor to be calibrated to 100 rpm, test each group of conditions one by one, and record the motor torque T ₁ , d-axis voltage U _d1 , q-axis voltage U _q1 , phase angle θ, and current I corresponding to each group after the motor to be calibrated runs stably. Make the motor torque T ₁ , d-axis voltage U _d1 , and q-axis voltage U _q1 into a table corresponding to the phase angle θ and the current I, as shown below:

Table 1

Table 2

table 3

S23: According to Table 1, Table 2 and Table 3, the maximum torque value T ₁ of each current can be found, and the phase angle θ ₁ corresponding to the maximum torque T ₁ can be obtained. According to the theory of permanent magnet synchronous motor, at different speeds within the constant torque area (non-weakening magnetic area), the same current produces the same torque, so the torque T ₁ and the phase angle θ ₁ are the optimal control performance parameters of the low-speed non-weakening magnetic area under different currents;

S31: According to the formula I _d =I·Cos(90°+θ), I _q =I·Sin(90°+θ), calculate the current I _d and the current I _q corresponding to each group of currents I;

S31: Calculate the total current I (0-400A), the total phase angle θ (0-90°), i.e., 209 groups of corresponding direct-axis flux Ψ _d and quadrature-axis flux Ψ _q at 100 rpm. The calculation formula for this step is:

We get 209 sets of Ψ _d and Ψ _q ,

Among them, R is the stator winding resistance, measured by a resistance meter, _ωe is the electrical angular velocity, which is related to the rotation speed,

S32: In the high-speed weak magnetic field area, calculate the d-axis voltage U _d2 and q-axis voltage U _q2 corresponding to different high speeds n ₂ at full current I (0-400A) and full phase angle θ (0-90°). The calculation formula for this step is:

U _d2 =R·I _d -ω _e ·ψ _q , U _q2 =R·I _q +ω _e ·ψ _d , and 209 groups of U _d2 and U _q2 corresponding to different high speeds n ₂ , different currents I and different phase angles θ are obtained;

U _s = sqrt(U _d2 ·U _d2 +U _q2 ·U _q2 ), 209 sets of U _s are obtained.

Among them, sqrt is the square root;

S34: Under different currents, use the interpolation method to find the 209 groups of U _s that can satisfy The phase angle θ value is the optimal current phase angle θ ₂ for different currents corresponding to different high speeds n ₂ .

Among them, U _dc is the DC high voltage, which is a performance parameter of the motor system, and K is the weak magnetic coefficient, which is a control parameter of the motor system;

S35: Under different high speeds n ₂ , according to the optimal phase angle θ ₂ of different currents, the corresponding torque T ₂ is obtained by combining the torque two-dimensional table in Table 1 with the interpolation algorithm, that is, the optimal phase angle and optimal torque of different currents under different speeds in the high speed range are obtained;

S4: Testing the no-load torque T ₃ at different speeds in the full speed range, i.e., the no-load loss torque, by suspending the three-phase cables of the motor to be calibrated, and controlling the motor to be calibrated to run at no-load at different speeds, and obtaining the no-load torque T ₃ at the corresponding speed;

S5: Calculate the mechanical torque T at different speeds in the full speed range. For the low speed weak magnetic area, the mechanical torque T=T ₁ -T ₃ , and for the high speed weak magnetic area, the mechanical torque T=T ₂ -T ₃ . Arrange the optimal performance parameters at different speeds in the full speed range into a table to complete the calibration.

From the above, it can be seen that in the calibration method of the permanent magnet synchronous motor performance provided by the present invention, the purpose is to find the optimal performance parameters, that is, the optimal performance, at different speeds in the full speed range; by dividing the full speed range into a low-speed non-weak magnetic zone and a high-speed weak magnetic zone, a comprehensive test of the motor to be calibrated is performed on a low speed in the low-speed non-weak magnetic zone to find out the optimal performance parameters of the low-speed non-weak magnetic zone, and for the high-speed weak magnetic zone, the optimal performance corresponding to different high speeds is derived through relevant calculations to complete the entire calibration process.

The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

A method for calibrating the performance of a permanent magnet synchronous motor, characterized in that the method comprises the following steps:

S1: Install the motor to be calibrated on the test bench, connect the motor to be calibrated with the motor controller, and the motor controller is connected with the high-voltage DC power supply;

S2: At low speed n 1 , the motor torque and voltage are tested one by one with full current I and full phase angle θ, and the maximum torque T 1 and corresponding phase angle θ 1 of each current in the low speed non-weakening magnetic zone are obtained;

S3: Obtain the optimal phase angle θ 2 and the corresponding torque T 2 of each current at different speeds n 2 in the high-speed weak magnetic zone by interpolation method;

S4: Test the no-load torque T 3 at different speeds in the full speed range, i.e. the no-load loss torque;

S5: Calculate the mechanical torque T at different speeds in the full speed range and organize it into a table to complete the calibration.
A method for calibrating the performance of a permanent magnet synchronous motor according to claim 1, characterized in that the full current I is 0-peak current, the full phase angle θ is 0-90°, and the current I increases by one tenth of the peak current from 0, and the phase angle θ increases by 5° from 0, that is, there are multiple groups of corresponding current I and phase angle θ.
The method for calibrating the performance of a permanent magnet synchronous motor according to claim 2 is characterized in that the current I d and the current I q corresponding to each group of currents I are calculated according to the formulas I d =I·Cos(90°+θ), I q =I· Sin (90°+θ).
The method for calibrating the performance of a permanent magnet synchronous motor according to claim 3 is characterized in that the specific steps of testing one by one in step 2 are: under each set of corresponding current I and phase angle θ, the motor to be calibrated is tested once, and after stable operation, the torque, d-axis voltage U d1 , and q-axis voltage U q1 are recorded each time to obtain multiple sets of data.
The method for calibrating the performance of a permanent magnet synchronous motor according to claim 4 is characterized in that: A two-dimensional torque table is obtained by tabulating multiple groups of data obtained from the test, and the maximum torque T 1 and the corresponding phase angle θ 1 of each current in the low-speed non-weakening magnetic region are obtained by comparison and sorting.
The method for calibrating the performance of a permanent magnet synchronous motor according to claim 5, characterized in that step 3 further comprises:

S31: Calculate the direct-axis flux Ψ d and the quadrature-axis flux Ψ q corresponding to the full current I and the full phase angle θ at low speed n 1. The calculation formula for this step is:

Get multiple sets of Ψ d and Ψ q ,

Among them, R is the stator winding resistance, measured by a resistance meter, ωe is the electrical angular velocity and is related to the rotational speed, n is the rotational speed,

S32: Calculate the d-axis voltage U d2 and q-axis voltage U q2 corresponding to the full current I and the full phase angle θ. The calculation formula for this step is:

U d2 =R·I d -ω e ·ψ q , U q2 =R·I q +ω e ·ψ d , and multiple groups of U d2 and U q2 corresponding to the full current I and the full phase angle θ in different speeds n 2 are obtained;

S33: In the high-speed weak magnetic field area, calculate the phase voltage U s corresponding to the full current I and the full phase angle θ at different high speeds n 2. The calculation formula for this step is:

U s = sqrt(U d2 ·U d2 +U q2 ·U q2 ), we get multiple groups of U s ,

Among them, sqrt is the square root;

S34: In the high-speed weak magnetic field area, for different high speeds n2 within the full current I, use the interpolation method to find the value that satisfies The phase angle θ 2 of the current is θ 2 , that is, θ 2 is the optimal phase angle θ 2 corresponding to each current of the full current I at different high speeds n 2 .

Among them, U dc is the direct current high voltage, which belongs to the motor system performance parameter, and K is the weak magnetic coefficient, which belongs to the motor system System control parameters;

S35: According to the optimal current phase angle θ 2 , the two-dimensional torque table in S1 is combined with an interpolation method to obtain the corresponding torque T 2 .
A method for calibrating the performance of a permanent magnet synchronous motor according to claim 6, characterized in that the value of the mechanical torque T at different speeds at full speed in step 4 is the difference between the optimal torque and the no-load torque T3 .