A method for calibrating performance of a permanent magnet synchronous motor

Abstract

The application relates to the motor technology field, and particularly discloses a kind of permanent magnet synchronous motor performance calibration methods, and the calibration method specific steps are: S1: to be calibrated motor is installed on the rack, to be calibrated motor is connected with motor controller, motor controller is connected with high-voltage direct-current power supply;S2: at low speed n1, full current I, full phase angle theta is tested motor torque, voltage one by one, obtains the maximum torque T1 of each current in low-speed non-weak magnetic area and corresponding phase angle theta 1;S3: the optimal phase angle theta 2 of each current of different speed n2 in high-speed weak magnetic area is obtained by interpolation method processing, and corresponding torque T2;S4: test the no-load torque T3 under different speeds in full speed area;S5: the mechanical torque T under different speeds in full speed area is calculated, and the calibration is completed by tabulation. The best performance parameter of to be calibrated motor under full speed area is found out by the calibration method, and the whole calibration process is safe and reliable, steps are quick, and accuracy is high.

Description

Technical Field

[0001] This invention relates to the field of motor technology, and specifically to a method for calibrating the performance of a permanent magnet synchronous motor. Background Technology

[0002] With the rise of new energy vehicles, permanent magnet synchronous motors are increasingly being used in these vehicles due to their advantages such as high efficiency, small size, and high power density. To achieve precise and safe control of permanent magnet synchronous motors, their performance needs to be calibrated.

[0003] To ensure optimal performance and safe operation of permanent magnet synchronous motors (PMSMs) across their entire operating range, testing on a test bench is necessary. During testing, accurate current calibration is required at designated operating points throughout the motor's speed and torque range. Currently, most PMSM performance calibration methods employ full-scan test calibration on a test bench, scanning every speed, current, and current phase angle across the entire speed range. However, this is labor-intensive and requires highly skilled and experienced calibration personnel, as high-speed calibration is dangerous and prone to accidents such as runaway motoring, communication interruptions, and excessive temperature rise leading to burnout. Another method utilizes motor simulation data provided by motor engineers. This method is convenient and quick, but the simulation data is not precise enough and may overlook saturation effects, end effects, and deviations in actual material properties and manufacturing consistency. Therefore, this method lacks accuracy and can sometimes result in significant deviations.

[0004] Therefore, a safer, more reliable, convenient, faster, and more accurate calibration method is needed to calibrate the performance of permanent magnet synchronous motors. Summary of the Invention

[0005] In order to overcome the problems of cumbersome steps, large workload, danger and inaccuracy in the existing calibration methods for permanent magnet synchronous motors, this invention provides a new calibration method for permanent magnet synchronous motors.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0007] A method for calibrating the performance of a permanent magnet synchronous motor, comprising the following steps:

[0008] S1: Install the motor to be calibrated on the test bench, connect the motor to the motor controller, and connect the motor controller to the high-voltage DC power supply.

[0009] S2: At low speed n1, the motor torque and voltage are tested one by one with full current I and full phase angle θ to obtain the maximum torque T1 and the corresponding phase angle θ1 of each current in the low-speed non-weakening field region.

[0010] S3: The optimal phase angle θ2 and stress torque T2 of different currents at different rotational speeds n2 in the high-speed field weakening region are obtained by interpolation.

[0011] S4: Test the no-load torque T3 at different speeds across the entire speed range, i.e., the no-load loss torque;

[0012] S5: Calculate the mechanical torque T at different speeds across the entire speed range, and compile it into a table to complete the calibration.

[0013] Furthermore, the range of the total current I is 0 to the peak current, and the range of the total phase angle θ is 0 to 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 sets of corresponding current I and phase angle θ.

[0014] Furthermore, according to Formula I d =I·Cos(90°+θ), I q =I·Sin(90°+θ), calculate the current I corresponding to each group of currents I. d and current I q .

[0015] Furthermore, the specific steps of the individual tests in step 2 are as follows: under each corresponding current I and phase angle θ, perform a test on the motor to be calibrated. After the motor to be calibrated runs stably, record the torque and d-axis voltage U for each test. d1 q-axis voltage U q1 This leads to multiple sets of data.

[0016] Preferably, a two-dimensional torque table is obtained by tabulating multiple sets of test data, and the maximum torque T1 and corresponding phase angle θ1 of each current in the low-speed non-weak magnetic region are obtained by comparison and sorting.

[0017] In the theory of permanent magnet synchronous motors, the same current produces the same torque at different speeds within the constant torque region (low-speed non-weakening field region). Therefore, the maximum torque T1 and the corresponding phase angle θ1 of each current in the low-speed non-weakening field region can be obtained by testing at low speed n1.

[0018] Furthermore, step 3 also includes:

[0019] S31: Calculate the direct-axis flux linkage Ψ corresponding to the total current I (0-peak current) and the total phase angle θ (0-90°) at low speed n1. d and cross-axis magnetic flux Ψ q The formula for this calculation step is as follows:

[0020] Multiple sets of Ψ were obtained dand Ψ q ,

[0021] Where R is the stator winding resistance, measured by a resistance meter, ω e The electric angular velocity is related to the rotational speed, where n is the rotational speed.

[0022] S32: Calculate the d-axis voltage U corresponding to different high-speed n2 under full current I (0-peak current) and full phase angle θ (0-90°). d2 q-axis voltage U q2 The calculation formula for this step is:

[0023] U d2 =R·I d –ω e ·ψ q U q2 =R·I q +ω e ·ψ d Multiple sets of U values ​​were obtained for different rotational speeds n2, different currents I2, and different phase angles θ. d2 and U q2 ;

[0024] S33: In the high-speed field weakening region, calculate the phase voltage U corresponding to different high-speed n2 at the full current I (0-peak current) and the full phase angle θ (0-90°). s The calculation formula for this step is:

[0025] U s =sqrt(U d2 ·U d2 +U q2 ·U q2 ), resulting in multiple sets of U s ,

[0026] Where sqrt represents the square root;

[0027] S34: In the high-speed field weakening region, for different high-speed n2 under full current I (0-peak current), use interpolation to find the value that satisfies... The value of the phase angle θ2 is the optimal phase angle θ2 under different high speeds and different currents.

[0028] Among them, U dc DC high voltage is a performance parameter of the motor system, while K is the field weakening coefficient, which is a control parameter of the motor system.

[0029] S35: Based on the optimal phase angle θ2 of different high speeds n2 under different currents, the torque T2 is obtained by combining the two-dimensional torque table in S2 with the interpolation method.

[0030] Furthermore, in step 4, the mechanical torque T at different speeds across the entire rotational speed is the difference between the optimal torque and the no-load torque T3.

[0031] Therefore, in this calibration process, the performance of the motor to be calibrated is tested at a low speed in the low-speed field weakening region, and the optimal performance parameters are found based on the test data. For the high-speed field weakening region, 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 obtained, thus completing the calibration of the motor performance.

[0032] The present invention has at least the following beneficial effects:

[0033] 1. The present invention provides a calibration method for the performance of a permanent magnet synchronous motor. This calibration method obtains the performance parameters of the motor under test at a low speed under full current and full phase angle by testing at a low speed, and then obtains the optimal performance parameters of the motor under test in the low-speed non-field weakening region, without the need to calibrate at each speed in the low-speed non-field weakening region.

[0034] 2. The present invention provides a calibration method for the performance of a permanent magnet synchronous motor. This calibration method obtains the optimal performance parameters at different high speeds in the high-speed field weakening region by calculation and interpolation based on the relevant data obtained at low speeds. This avoids testing the performance parameters of the motor to be calibrated at high speeds, making the calibration process safer, more reliable, and faster.

[0035] 3. The present invention provides a calibration method for the performance of a permanent magnet synchronous motor, which makes the final measured optimal torque more accurate by testing the no-load torque at different speeds. Attached Figure Description

[0036] Figure 1 A flowchart of a method for calibrating the performance of a permanent magnet synchronous motor provided by the present invention. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0038] Example 1

[0039] This invention discloses a method for calibrating the performance of a permanent magnet synchronous motor, which specifically includes the following steps:

[0040] S1: Install the motor to be calibrated on the test bench, connect the motor to the motor controller, connect the motor controller to the high voltage DC power supply, and apply a current I with a phase angle of θ to the motor to be calibrated.

[0041] S21: The current I starts from 0 and gradually increases to a peak current of 400A with 11 values. The current phase angle θ starts from 0 and gradually increases to 90° with 5° with 19 values. That is, there are a total of 209 sets of current I and phase angle θ.

[0042] S22: Control the speed of the motor to be calibrated to 100 rpm, test each group one by one, and record the motor torque T1 and d-axis voltage U corresponding to each group after the motor to be calibrated runs stably. d1 q-axis voltage U q1 Phase angle θ, current I, motor torque T1, d-axis voltage U d1 q-axis voltage U q1 A table showing the one-to-one correspondence between phase angle θ and current I is presented below:

[0043]

[0044] Table 1

[0045]

[0046] Table 2

[0047]

[0048] Table 3

[0049] S23: According to Tables 1, 2 and 3, the maximum torque value T1 for each current can be found, and the phase angle θ1 corresponding to the maximum torque T1 can be obtained. According to the theory of permanent magnet synchronous motor, at different speeds within the constant torque region (non-weakening field region), the same current produces the same torque. Therefore, the torque T1 and the phase angle θ1 are the optimal control performance parameters for different currents in the low-speed non-weakening field region.

[0050] S31: According to Formula I d =I·Cos(90°+θ), I q =I·Sin(90°+θ), calculate the current I corresponding to each group of currents I. d and current I q ;

[0051] S31: Calculate the direct-axis flux linkage Ψ corresponding to the total current I (0-400A) and the total phase angle θ (0-90°) at 100 rpm, which is 209 sets. d and cross-axis magnetic flux Ψ q The formula for this calculation step is as follows:

[0052] 209 sets of Ψ were obtained d and Ψ q ,

[0053] Where R is the stator winding resistance, measured by a resistance meter, ω e It is the electric angular velocity, which is related to the rotational speed.

[0054] S32: In the high-speed field weakening region, calculate the d-axis voltage U corresponding to different high-speed n2 under full current I (0-400A) and full phase angle θ (0-90°). d2 q-axis voltage U q2 The calculation formula for this step is:

[0055] U d2 =R·I d –ω e ·ψ q U q2 =R·I q +ω e ·ψ d 209 sets of U values ​​were obtained for different high speeds n2, different currents I, and different phase angles θ. d2 and U q2 ;

[0056] S33: In the high-speed field weakening region, calculate the phase voltage U corresponding to different high-speed n2 at the full current I (0-peak current) and the full phase angle θ (0-90°). s The calculation formula for this step is:

[0057] U s =sqrt(U d2 ·U d2 +U q2 ·U q2 ), resulting in 209 sets of Us,

[0058] Where sqrt represents the square root;

[0059] S34: Find 209 sets of U values ​​under different currents using interpolation. s Medium can meet The phase angle θ value is the optimal current phase angle θ2 corresponding to different currents at different high speeds n2.

[0060] Among them, U dc is DC high voltage, which belongs to the performance parameters of the motor system; K is the field weakening coefficient, which belongs to the control parameters of the motor system.

[0061] S35: Under different high speeds n2, based on the optimal phase angle θ2 of different currents, the corresponding torque T is obtained from the two-dimensional torque table in Table 1 combined with an interpolation algorithm. 2， That is, to obtain the optimal phase angle and optimal torque of different currents at different speeds in the high-speed range;

[0062] S4: Test the no-load torque T3 at different speeds across the entire speed range, i.e., the no-load loss torque. With the three-phase cables of the motor to be calibrated suspended, control the motor to be calibrated to run under no-load at different speeds, and obtain the no-load torque T3 at the corresponding speed.

[0063] S5: Calculate the mechanical torque T at different speeds across the entire speed range. For the low-speed field weakening region, the mechanical torque T = T1 - T3. For the high-speed field weakening region, the mechanical torque T = T2 - T3. Compile the optimal performance parameters at different speeds across the entire speed range into a table to complete the calibration.

[0064] In summary, the purpose of the calibration method for permanent magnet synchronous motor performance provided by this invention is to find the optimal performance parameters, i.e., the best performance, at different speeds across the entire speed range. By dividing the entire speed range into a low-speed non-field weakening region and a high-speed field weakening region, the optimal performance parameters of the motor to be calibrated are found by conducting comprehensive tests on a low speed in the low-speed non-field weakening region. For the high-speed field weakening region, the optimal performance corresponding to different high speeds is derived through relevant calculations, thus completing the entire calibration process.

[0065] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A method for calibrating the performance of a permanent magnet synchronous motor, characterized in that, This calibration method includes the following steps: S1: Install the motor to be calibrated on the test bench, connect the motor to the motor controller, and connect the motor controller to the high-voltage DC power supply. S2: At low speed n1, the motor torque and voltage are tested one by one with full current I and full phase angle θ to obtain the maximum torque T1 and the corresponding phase angle θ1 of each current in the low-speed non-weakening field region. S3: The optimal phase angle θ2 and the corresponding torque T2 of each current at different rotational speeds n2 in the high-speed field weakening region are obtained by interpolation. S4: Test the no-load torque T3 at different speeds across the entire speed range, i.e., the no-load loss torque; S5: Calculate the mechanical torque T at different speeds across the entire speed range, and compile it into a table to complete the calibration; Wherein, according to formula I d =I·Cos(90°+θ), I q =I·Sin(90°+θ), calculate the current I corresponding to each group of currents I. d and current I q ; The specific steps of the step 2 test are as follows: under each corresponding current I and phase angle θ, perform a test on the motor to be calibrated, and after the operation is stable, record the torque and d-axis voltage U for each test. d1 q-axis voltage U q1 Multiple sets of data were obtained; Step 3 further includes: S31: Calculate the direct-axis flux linkage Ψ corresponding to the total current I and the total phase angle θ at low speed n1. d and cross-axis magnetic flux Ψ q The formula for this calculation step is as follows: Multiple sets of Ψ were obtained d and Ψ q , Where R is the stator winding resistance, measured by a resistance meter, ω e The electric angular velocity is related to the rotational speed, where n is the rotational speed. S32: Calculate the d-axis voltage U corresponding to the total current I and the total phase angle θ. d2 q-axis voltage U q2 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 Multiple sets of U values ​​were obtained for the total current I and the total phase angle θ at different rotational speeds n2. d2 and U q2 ; S33: In the high-speed field weakening region, calculate the phase voltage U corresponding to the total current I and the total phase angle θ for different high speeds n2. s The calculation formula for this step is: U s = sqrt(U d2 U d2 +U q2 U q2 ),Get a lot of pairs U s , Where sqrt represents the square root; S34: In the high-speed field weakening region, for different high-speed n2 within the total current I, interpolation is used to find the value that satisfies... The phase angle θ2, that is, θ2 is the optimal phase angle θ2 corresponding to each current I of the total current for different high speeds n2. Among them, U dc DC high voltage is a performance parameter of the motor system, while K is the field weakening coefficient, which is a control parameter of the motor system. S35: Based on the optimal current phase angle θ2, the torque T2 is obtained by combining the two-dimensional torque table in S1 with the interpolation method.

2. The method for calibrating the performance of a permanent magnet synchronous motor according to claim 1, characterized in that, The total current I is 0 to the peak current, and the total phase angle θ is 0 to 90°. The current I increases by one-tenth of the peak current starting from 0, and the phase angle θ increases by 5° starting from 0. That is, there are multiple sets of corresponding current I and phase angle θ.

3. The method for calibrating the performance of a permanent magnet synchronous motor according to claim 2, characterized in that, By tabulating multiple sets of test data, a two-dimensional torque table was obtained. By comparing and organizing the data, the maximum torque T1 and the corresponding phase angle θ1 of each current in the low-speed non-weak magnetic region were obtained.

4. The method for calibrating the performance of a permanent magnet synchronous motor according to claim 3, characterized in that, The mechanical torque T at different speeds in step 4 is the difference between the optimal torque and the no-load torque T3.

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