Permanent magnet synchronous motor calibration method, maximum torque current ratio calibration method and device

Abstract

The embodiment of the application provides a permanent magnet synchronous motor calibration method, a maximum torque current ratio calibration method and equipment, the maximum torque current ratio calibration method comprises: a power-on step, an initialization step and a calibration step, a target current Is and a current vector angle θ of a measured motor are adjusted alternately and circularly through a host computer, in each alternately and circularly adjusting period, the target current Is is first adjusted to increase from a starting current value to make the torque of the measured motor reach a next calibration torque point of a calibration torque interval, then the current vector angle θ of the measured motor is adjusted to change from a starting vector angle until the torque of the measured motor is maximum, and the current target current Is and the current current vector angle are taken as a calibration peak current and a calibration current vector angle of a current calibration torque point respectively; a direct-axis and quadrature-axis current calculation step, the calibration direct-axis current Id and the calibration quadrature-axis current Iq of the calibration torque point are calculated. The embodiment can improve calibration efficiency and reduce calibration error.

Description

Technical Field

[0001] This invention relates to the field of permanent magnet synchronous motor technology, and in particular to a calibration method for permanent magnet synchronous motors, a maximum torque-to-current ratio calibration method and equipment. Background Technology

[0002] Currently, most drive motors used in electric vehicles are embedded permanent magnet synchronous motors (IPMSMs). To improve system efficiency, the maximum torque-to-current ratio (MTPA) control method is required during low-speed motor operation. A prerequisite for implementing the MTPA control method is to effectively calibrate the maximum torque-to-current ratio of the permanent magnet synchronous motor beforehand.

[0003] One existing method for calibrating the maximum torque-current ratio (MTPA) of a permanent magnet synchronous motor is to select a relatively high speed in the torque range of the motor under test, scan the relationship between the target peak current (the combined current of the direct-axis current and the quadrature-axis current) and the torque of the motor under test, and then select a relatively good current-torque relationship curve from the scan results as the MTPA curve.

[0004] However, the inventors found in practice that the above calibration method selects a relatively good one from multiple current-torque relationship curves as the MTPA curve of the motor under test, which has a large error and requires complex screening and judgment from a large amount of data, resulting in relatively low calibration efficiency. Summary of the Invention

[0005] The technical problem to be solved by the embodiments of the present invention is to provide a method for calibrating the maximum torque-current ratio of a permanent magnet synchronous motor, which can effectively improve calibration efficiency and reduce calibration error.

[0006] A further technical problem to be solved by the embodiments of the present invention is to provide a calibration device for calibrating the maximum torque-current ratio of a permanent magnet synchronous motor, which can effectively improve calibration efficiency and reduce calibration error.

[0007] A further technical problem to be solved by the embodiments of the present invention is to provide a calibration method for permanent magnet synchronous motors, which can effectively improve calibration efficiency and reduce calibration error.

[0008] To address the aforementioned technical problems, this invention first provides the following technical solution: a method for calibrating the maximum torque-to-current ratio of a permanent magnet synchronous motor, comprising the following steps:

[0009] In the power-on step, the host computer in the calibration equipment controls the DC power supply in the calibration equipment to power on the motor under test and the auxiliary motor installed on the calibration equipment, and controls the auxiliary motor to maintain the speed of the motor under test at the turning speed of the motor under test. The host computer has the calibration torque range of the motor under test stored in advance.

[0010] In the initialization step, the host computer sets the current vector angle θ of the motor under test to a predetermined starting vector angle. At the same time, the host computer adjusts the target current Is of the motor under test to gradually increase until the torque of the motor under test reaches the zero torque point of the calibrated torque range, and records the target current Is at this time as the starting current value.

[0011] The calibration process involves the host computer alternately and cyclically adjusting the target current Is and the current vector angle θ of the motor under test. Within each alternating cycle, the target current Is is first increased from its initial value until the torque of the motor under test reaches the next calibration torque point within the calibration torque range. Then, the current target current Is is kept constant while the current vector angle θ is adjusted from its initial value until the torque of the motor under test reaches its maximum. At the end of each alternating cycle, the initial current value is updated with the current target current Is, and the initial vector angle θ is updated with the current current vector angle θ. The current target current Is and the current current vector angle θ are then used as the calibration peak current and calibration current vector angle for the current calibration torque point, respectively.

[0012] The calculation steps for the direct and quadrature axis currents are as follows: based on the correspondence between the calibrated direct axis current Id and the calibrated quadrature axis current Iq of the motor under test and the calibrated peak current and current vector angle θ, the calibrated direct axis current Id and the calibrated quadrature axis current Iq of each calibrated torque point within the calibrated torque range are calculated, thus completing the maximum torque-current ratio calibration of the motor under test.

[0013] Furthermore, starting from the second alternating cycle adjustment period, when adjusting the target current Is, the adjustment increment of the target current Is in the previous alternating cycle adjustment period is used as the adjustment step of the current alternating cycle adjustment period.

[0014] Furthermore, starting from the second alternating cycle adjustment period, when adjusting the current vector angle θ, the adjustment increment of the current vector angle θ in the previous alternating cycle adjustment period is first increased, and then the current vector angle θ of the motor under test is increased by a preset unit adjustment amount. Then it is determined whether the torque of the motor under test has increased. If it is determined that the torque of the motor under test has increased, the current vector angle θ of the motor under test is continuously increased according to the unit adjustment amount until the torque of the motor under test remains unchanged. Otherwise, the current vector angle θ of the motor under test is gradually decreased according to the unit adjustment amount until the torque of the motor under test is further reduced. The rated torque range of the motor under test is determined by the external characteristic curve of the motor under test.

[0015] On the other hand, in order to solve the above-mentioned further technical problems, the embodiments of the present invention further provide the following technical solution: a calibration device for calibrating the maximum torque-current ratio of a permanent magnet synchronous motor, comprising:

[0016] A test bench on which the motor to be tested is mounted;

[0017] The test motor is used to connect to the motor under test to maintain the rotational speed of the motor under test as its turning speed.

[0018] A DC power supply, connected to both the motor under test and the auxiliary motor, is used to power on both motors respectively; and

[0019] The host computer is connected to the motor under test and the auxiliary motor under test respectively. It is used to pre-store the calibration torque range of the motor under test and control the operation status of the motor under test and the auxiliary motor under test accordingly, as well as to perform calculation and processing on the data collected during the calibration process.

[0020] The host computer includes:

[0021] The power-on control module is used to control the DC power supply to power on the motor under test and the auxiliary motor installed on the calibration equipment, and to control the auxiliary motor to maintain the speed of the motor under test at the turning speed of the motor under test. The host computer has the calibration torque range of the motor under test stored in advance.

[0022] The initialization module is used to set the current vector angle θ of the motor under test to a predetermined starting vector angle, and at the same time adjust the target current Is of the motor under test to gradually increase until the torque of the motor under test reaches the zero torque point of the calibrated torque range, and record the target current Is at this time as the starting current value.

[0023] The calibration module is used to alternately and cyclically adjust the target current Is and the current vector angle θ of the motor under test. In each alternating cycle, the target current Is is first increased from its initial value until the torque of the motor under test reaches the next calibration torque point in the calibration torque range. Then, the current target current Is is kept constant while the current vector angle θ of the motor under test is adjusted from its initial value until the torque of the motor under test reaches its maximum. At the end of each alternating cycle, the initial current value is updated with the current target current Is, and the initial vector angle θ is updated with the current current vector angle θ. The current target current Is and the current current vector angle θ are used as the calibration peak current and calibration current vector angle of the current calibration torque point, respectively.

[0024] The direct-axis and quadrature-axis current calculation module is used to calculate the calibrated direct-axis current Id and calibrated quadrature-axis current Iq at each calibrated torque point within the calibrated torque range based on the correspondence between the calibrated direct-axis current Id and calibrated quadrature-axis current Iq of the motor under test and the calibrated peak current and current vector angle θ, thereby completing the maximum torque-current ratio calibration of the motor under test.

[0025] Furthermore, to address the aforementioned technical problems, this invention provides the following technical solution: a calibration method for a permanent magnet synchronous motor, comprising the following steps:

[0026] The maximum torque-current ratio of the motor under test is calibrated using any of the above-described maximum torque-current ratio calibration methods; and

[0027] The field weakening calibration of the motor under test is completed based on the maximum torque-to-current ratio calibration of the motor under test.

[0028] Furthermore, the host computer also pre-stores the calibration speed range, calibration power range, and calibration bus voltage range of the motor under test. The calibration based on the maximum torque-to-current ratio of the motor under test to complete the field weakening calibration of the motor under test specifically includes:

[0029] The initial quantity determination step involves determining the initial direct-axis current and initial quadrature-axis current of the motor under test at the calibration speed point based on the maximum torque-current ratio calibration of the motor under test.

[0030] The step value determination process involves gradually increasing the speed of the motor under test via the host computer until the speed reaches the first calibrated speed point within the calibrated speed range. Based on the current direct-axis voltage Ud and quadrature-axis voltage Uq of the motor under test, the actual phase voltage U of the motor under test is calculated. 实 Based on the calibration bus voltage range, determine the peak phase voltage Usmax at the current calibration speed point of the motor under test, and compare it with the actual phase voltage U. 实 And the peak phase voltage Usmax, when the actual phase voltage U 实 When the actual phase voltage U is greater than the peak phase voltage Usmax, the actual phase voltage U 实 The difference between the phase voltage peak value Usmax and the actual power P of the motor under test is input to the PI controller of the test bench to calculate the direct-axis current step value of the motor under test. 实 Based on the calibrated power range, determine the target power P of the motor under test at the current calibrated speed point. 目 Compare the actual power P 实 and target power P 目 The actual power P 实 With target power P 目The difference is input to the PI controller to calculate the quadrature-axis current step value of the motor under test. Based on the direct-axis current step value and the quadrature-axis current step value, the initial direct-axis current and the initial quadrature-axis current are corrected accordingly. The corrected initial direct-axis current and the initial quadrature-axis current are used as the calibration direct-axis current Id and the calibration quadrature-axis current Iq at the current calibration speed point; and

[0031] The speed calibration cycle step is to repeatedly execute the step value determination step until the calibration direct-axis current Id and calibration quadrature-axis current Iq corresponding to each calibration speed point are obtained.

[0032] Furthermore, after the speed calibration cycle step, the following steps are performed:

[0033] The function fitting step involves fitting the calibrated direct-axis current Id and calibrated quadrature-axis current Iq at each calibrated torque point and the calibrated direct-axis current Id and calibrated quadrature-axis current Iq at each calibrated speed point of the motor under test, based on a preset linear fitting method, to obtain a fitting function. The fitting function uses the torque and speed of the motor under test as independent variables and the calibrated direct-axis current Id and calibrated quadrature-axis current Iq of the motor under test as dependent variables.

[0034] Furthermore, after the function fitting step, the following steps are performed:

[0035] The relationship table generation step involves calculating the relationship table of the motor's speed, torque, calibrated direct-axis current Id, and calibrated quadrature-axis current Iq under different bus voltages based on pre-stored correspondences between the bus voltage and speed of the motor under test and the fitting function; and

[0036] The relation table correction step involves actually verifying the corresponding relation table to correct each variable in the relation table.

[0037] Furthermore, the rated torque range, rated speed range, rated power range, and rated bus voltage range of the motor under test are all determined by the external characteristic curve of the motor under test.

[0038] After adopting the above technical solution, the embodiments of the present invention have at least the following beneficial effects: In the embodiments of the present invention, after powering on the tested motor and the auxiliary tested motor via a DC power supply on the calibration equipment, the auxiliary tested motor on the calibration equipment maintains the tested motor's rotational speed at the tested motor's turning speed. Under the premise that the tested motor's rotational speed remains constant, the maximum torque-to-current ratio is calibrated. Then, the current vector angle θ of the tested motor is set as a predetermined starting vector angle. Simultaneously, the target current Is of the tested motor is gradually increased through the host computer until the tested motor's torque reaches the zero torque point of the calibrated torque range. Utilizing the embedded permanent magnet synchronous motor, whose reluctance torque is small when the current is small, the influence of the tested motor's rotational inertia is offset, which helps improve the accuracy of the calibration. In each alternating cyclic adjustment cycle, based on the principle of the controlled variable method, the current vector angle and the target peak current Is of the tested motor are kept constant to allow the tested motor to reach the next torque point and maximize the torque of the tested motor. The embedded permanent magnet synchronous motor maximizes the utilization of reluctance torque. By gradually changing the current vector angle θ of the tested motor, the maximum torque that the tested motor can output under the premise of keeping the target peak current Is constant is determined, i.e., the maximum torque-current ratio. Finally, based on the recorded target current Is and current vector angle θ, the calibration direct-axis current Id and calibration quadrature-axis current Iq of each calibration torque point are calculated to complete the calibration of the maximum torque-current ratio of the tested motor. The overall calibration process is highly automated and does not require a lot of data screening and judgment, resulting in higher calibration efficiency and accuracy. Attached Figure Description

[0039] Figure 1 This is a flowchart of an optional embodiment of the maximum torque-to-current ratio calibration method for a permanent magnet synchronous motor according to the present invention.

[0040] Figure 2 This is a schematic diagram of a calibration device for an optional embodiment of the permanent magnet synchronous motor of the present invention.

[0041] Figure 3 This is a functional block diagram of the host computer of the calibration device for an optional embodiment of the permanent magnet synchronous motor of the present invention.

[0042] Figure 4 The flowchart below shows a specific step S2 of an optional embodiment of the permanent magnet synchronous motor calibration method of the present invention. Detailed Implementation

[0043] The present application will now be described in further detail with reference to the accompanying drawings and specific embodiments. It should be understood that the following illustrative embodiments and descriptions are only used to explain the present invention and are not intended to limit the present invention. Moreover, the embodiments and features in the embodiments of the present application can be combined with each other unless otherwise specified.

[0044] like Figures 1-2As shown, an optional embodiment of the present invention provides a method for calibrating the maximum torque-to-current ratio of a permanent magnet synchronous motor, comprising the following steps:

[0045] S11: Power-on step, the host computer in the calibration equipment controls the DC power supply in the calibration equipment to power on the motor under test and the auxiliary motor installed on the calibration equipment, and controls the auxiliary motor to maintain the speed of the motor under test at the turning speed of the motor under test. The host computer has the calibration torque range of the motor under test stored in advance.

[0046] S12: Initialization step: The host computer sets the current vector angle θ of the motor under test to a predetermined starting vector angle. At the same time, the host computer adjusts the target current Is of the motor under test to gradually increase until the torque of the motor under test reaches the zero torque point of the calibrated torque range, and records the target current Is at this time as the starting current value.

[0047] S13: Calibration step: The host computer alternately and cyclically adjusts the target current Is and current vector angle θ of the motor under test. In each alternating cycle, the target current Is is first increased from its initial value to bring the torque of the motor under test to the next calibration torque point within the calibration torque range. Then, the current target current Is is kept constant while the current vector angle θ of the motor under test is adjusted from its initial value until the torque of the motor under test reaches its maximum. At the end of each alternating cycle, the initial current value is updated with the current target current Is, and the initial vector angle θ is updated with the current current vector angle θ. The current target current Is and the current current vector angle θ are used as the calibration peak current and calibration current vector angle of the current calibration torque point, respectively.

[0048] S14: The calculation steps for the direct and quadrature axis currents are as follows: Based on the correspondence between the calibrated direct axis current Id and the calibrated quadrature axis current Iq of the motor under test and the calibrated peak current and current vector angle θ, the calibrated direct axis current Id and the calibrated quadrature axis current Iq of each calibrated torque point in the calibrated torque range are calculated, thus completing the calibration of the maximum torque-current ratio of the motor under test.

[0049] In this embodiment of the invention, after powering on the motor under test and the auxiliary motor via a DC power supply on the calibration equipment, the auxiliary motor on the calibration equipment maintains the rotational speed of the motor under test at its turning speed. While keeping the rotational speed of the motor under test constant, the maximum torque-to-current ratio is calibrated. Then, the current vector angle θ of the motor under test is set as a predetermined starting vector angle. Simultaneously, the target current Is of the motor under test is gradually increased via the host computer until the torque of the motor under test reaches the zero torque point of the calibration torque range. Utilizing the embedded permanent magnet synchronous motor, whose reluctance torque is small when the current is low, the influence of the rotational inertia of the motor under test is offset, which helps improve the accuracy of the calibration. Furthermore, within each alternating cyclic adjustment cycle... Based on the principle of the controlled variable method, the current vector angle and target peak current Is of the motor under test are kept constant to allow the motor under test to reach the next torque point and maximize the torque of the motor under test. The embedded permanent magnet synchronous motor maximizes the use of reluctance torque. By gradually changing the current vector angle θ of the motor under test, the maximum torque that the motor under test can output under the premise of keeping the target peak current Is constant is determined, i.e., the maximum torque-current ratio. Finally, based on the recorded target current Is and current vector angle θ, the calibration direct-axis current Id and calibration quadrature-axis current Iq of each calibration torque point are calculated to complete the calibration of the maximum torque-current ratio of the motor under test. The overall calibration process is highly automated and does not require a lot of data screening and judgment, resulting in higher calibration efficiency and accuracy.

[0050] For example: The maximum speed of the motor under test is 12000 rpm, the output torque is 300 Nm, and the working power is 150 kW. The turning speed of the motor under test can be calculated as 4775 rpm using the following formula:

[0051] (Formula 1)

[0052] Where P represents the motor's mechanical power, Te represents the motor's mechanical torque, and Speed ​​represents the motor's rotational speed;

[0053] As can be seen from the above turning points, the speed of the motor under test is in the power range above 4775 rpm and in the torque range below 4775 rpm. In addition, in order to effectively protect the motor under test, it is necessary to obtain the external characteristic curve of the motor and confirm the peak current required at each speed as the protection value.

[0054] Based on the relevant parameters of the motor under test, and without considering the attenuation of peak power after the motor enters the field weakening zone II, its calibration bus voltage range is as follows:

[0055] [250, 330, 420];

[0056] The calibrated speed range is:

[0057] [200, 1000, 2000, 3000, 4000, 5000, 6000, 7000, 8000, 9000, 10000, 11000, 12000];

[0058] The rated torque range is:

[0059] [-300, -270, -240, -210, -180, -150, -120, -90, -60, -30, 0, 30, 60, 90, 120, 150, 180, 210, 240, 270, 300];

[0060] The rated power range is:

[0061] [-150, -135, -120, -105, -90, -75, -60, -45, -30, -15, 0, 15, 30, 45, 60, 75, 90, 105, 120, 135, 150].

[0062] Furthermore, the corresponding relationships between the calibrated direct-axis current Id and the calibrated quadrature-axis current Iq of the tested motor and the calibrated peak current and current vector angle θ are as follows:

[0063] (Formula 2)

[0064] Where Is represents the calibrated peak current, and the current vector angle θ varies in the range of [90, 180].

[0065] like Figure 2 As shown, the accompanying motor is responsible for maintaining the speed during the calibration process, while the output torque of the motor under test is calibrated. The host computer obtains parameters such as bus voltage, speed, torque, DQ axis current, and DQ axis voltage from the controller of the motor under test, communicates with the speed and torque sensors to obtain the motor's speed and torque, and communicates with the power analyzer to obtain information such as AC voltage, AC current, AC power, DC voltage, DC current, and DC power.

[0066] In an optional embodiment of the present invention, starting from the second alternating cycle adjustment period, when adjusting the target current Is, the adjustment increment of the target current Is in the previous alternating cycle adjustment period is used as the adjustment step of the current adjustment period. In this embodiment, starting from the second alternating cycle adjustment period, the target current Is is directly adjusted using the adjustment increment of the previous alternating cycle adjustment period, which can effectively simplify the adjustment process of the target current Is and improve the calibration efficiency.

[0067] In an optional embodiment of the present invention, starting from the second alternating cycle adjustment period, when adjusting the current vector angle θ, the adjustment increment of the current vector angle θ in the previous alternating cycle adjustment period is first increased, and then the current vector angle θ of the motor under test is increased by a preset unit adjustment amount. Then it is determined whether the torque of the motor under test has increased. If it is determined that the torque of the motor under test has increased, the current vector angle θ of the motor under test is continuously increased by the unit adjustment amount until the torque of the motor under test remains unchanged. Otherwise, the current vector angle θ of the motor under test is gradually decreased by the unit adjustment amount until the torque of the motor under test remains unchanged.

[0068] In this embodiment, firstly, the adjustment increment of the current vector angle θ in the previous alternating cycle is increased to simplify the adjustment process. Then, the current vector angle θ is adjusted by controlling the increase and decrease of the current vector angle θ of the motor under test, thereby finding the maximum torque that the motor under test can output under the current target current and maximizing the utilization of the reluctance torque of the built-in permanent magnet synchronous motor.

[0069] In specific implementation, the predetermined starting vector angle is 90 degrees. In this embodiment, the predetermined starting vector angle is 90 degrees. On the one hand, it can effectively offset the zero torque error caused by the moment of inertia by adjusting the target current of the motor under test. On the other hand, when the current of the embedded permanent magnet synchronous motor is small, its magnetic reluctance torque is not large. Setting the predetermined starting vector angle to 90 degrees can effectively shorten the calibration time.

[0070] In an optional embodiment of the present invention, the rated torque range of the motor under test is determined by the external characteristic curve of the motor under test. In this embodiment, by determining the rated torque range of the motor under test based on the external characteristic curve of the motor under test, an accurate rated torque range can be obtained based on the actual parameters of the motor under test, which is beneficial to improving the accuracy of calibration.

[0071] On the other hand, such as Figure 2 and Figure 3 As shown, in order to solve the above-mentioned further technical problems, this embodiment of the invention further provides a calibration device for calibrating the maximum torque-to-current ratio of a permanent magnet synchronous motor, comprising:

[0072] A test bench on which the motor to be tested is mounted;

[0073] The test motor is used to connect to the motor under test to maintain the rotational speed of the motor under test as its turning speed.

[0074] A DC power supply, connected to both the motor under test and the auxiliary motor, is used to power on both motors respectively; and

[0075] A host computer, connected to both the motor under test and the auxiliary motor under test, is used to pre-store the calibration torque range of the motor under test, control the operating states of both the motor under test and the auxiliary motor, and process the data collected during the calibration process; the host computer includes:

[0076] The power-on control module 10 is used to control the DC power supply to power on the motor under test and the auxiliary motor installed on the calibration equipment, and to control the auxiliary motor to maintain the speed of the motor under test at the turning speed of the motor under test. The host computer has a pre-stored calibration torque range of the motor under test.

[0077] The initialization module 12 is used to set the current vector angle θ of the motor under test to a predetermined starting vector angle, and at the same time adjust the target current Is of the motor under test to gradually increase until the torque of the motor under test reaches the zero torque point of the calibrated torque range, and record the target current Is at this time as the starting current value.

[0078] Calibration module 14 is used to alternately and cyclically adjust the target current Is and current vector angle θ of the motor under test. In each alternating cyclic adjustment cycle, the target current Is is first adjusted to increase from the initial current value until the torque of the motor under test reaches the next calibration torque point in the calibration torque range. Then, the current target current Is is kept constant while the current vector angle θ of the motor under test is adjusted from the initial vector angle until the torque of the motor under test is at its maximum. At the end of each alternating cyclic adjustment cycle, the initial current value is updated with the current target current Is, and the initial vector angle θ is updated with the current current vector angle θ. The current target current Is and the current current vector angle θ are used as the calibration peak current and calibration current vector angle of the current calibration torque point, respectively.

[0079] The quadrature-axis current calculation module 16 is used to calculate the calibrated direct-axis current Id and calibrated quadrature-axis current Iq at each calibrated torque point within the calibrated torque range based on the correspondence between the calibrated direct-axis current Id and the calibrated quadrature-axis current Iq of the motor under test and the calibrated peak current and current vector angle θ, thereby completing the maximum torque-current ratio calibration of the motor under test.

[0080] In this embodiment, when the calibration device calibrates the maximum torque-current ratio of the motor under test, the host computer executes the above steps S11-S14 through the power-on control module 10, initialization module 12, calibration module 14 and AC-DC axis current calculation module 16, which can effectively improve calibration efficiency and reduce calibration error.

[0081] Furthermore, this invention provides a calibration method for a permanent magnet synchronous motor, comprising the following steps:

[0082] S1: The maximum torque-current ratio calibration of the motor under test is completed using any of the above-described maximum torque-current ratio calibration methods; and

[0083] S2: Based on the maximum torque-to-current ratio calibration of the motor under test, complete the field weakening calibration of the motor under test.

[0084] In this embodiment of the permanent magnet synchronous motor calibration method, the maximum torque-current ratio calibration method described in the above embodiment is used to complete the field weakening calibration of the motor under test, which can effectively improve the calibration efficiency of the permanent magnet synchronous motor and reduce the calibration error.

[0085] In an optional embodiment of the present invention, such as Figure 4 As shown, the host computer pre-stores the calibration speed range, calibration power range, and calibration bus voltage range of the motor under test. Step S2 specifically includes:

[0086] S21: Initial quantity determination step, determine the initial direct-axis current and initial quadrature-axis current of the motor under test at the calibration speed point based on the maximum torque-current ratio calibration of the motor under test;

[0087] S22: Step value determination step, the host computer adjusts the speed of the motor under test to gradually increase until the speed of the motor under test reaches the first calibration speed point of the calibration speed range, and calculates the actual phase voltage U of the motor under test based on the current direct-axis voltage Ud and quadrature-axis voltage Uq of the motor under test. 实 Based on the calibration bus voltage range, determine the peak phase voltage Usmax at the current calibration speed point of the motor under test, and compare it with the actual phase voltage U. 实 And the peak phase voltage Usmax, when the actual phase voltage U 实 When the actual phase voltage U is greater than the peak phase voltage Usmax, the actual phase voltage U 实 The difference between the phase voltage peak value Usmax and the actual power P of the motor under test is input to the PI controller of the test bench to calculate the direct-axis current step value of the motor under test. 实 Based on the calibrated power range, determine the target power P of the motor under test at the current calibrated speed point. 目 Compare the actual power P 实 and target power P 目 The actual power P 实 With target power P 目 The difference is input to the PI controller to calculate the quadrature-axis current step value of the motor under test. Based on the direct-axis current step value and the quadrature-axis current step value, the initial direct-axis current and the initial quadrature-axis current are corrected accordingly. The corrected initial direct-axis current and the initial quadrature-axis current are used as the calibration direct-axis current Id and the calibration quadrature-axis current Iq at the current calibration speed point; and

[0088] S23: Speed ​​calibration cycle step, repeatedly execute the step value determination step until the calibration direct axis current Id and calibration quadrature axis current Iq corresponding to each calibration speed point are obtained.

[0089] Since the back electromotive force of a permanent magnet synchronous motor is proportional to its speed, its operation is limited by the inverter's maximum output voltage as the speed increases. Once the maximum output voltage is reached, the armature winding current cannot increase further. Based on this characteristic, after the inverter output voltage reaches its maximum value, the motor's magnetic field is weakened to allow the motor to operate above its rated speed, thus satisfying constant power control and wide speed range operation. This embodiment uses the above method, employing the actual phase voltage U at each calibrated speed point... 实 The difference between the peak phase voltage Usmax and the actual power P at each calibrated speed point is used to achieve field weakening control of the direct-axis current of the motor under test. 实 With target power P 目 The difference is used to achieve field weakening control of the quadrature axis current of the motor under test, which can effectively achieve field weakening calibration at each calibration speed point.

[0090] In practical implementation, the actual phase voltage U is calculated according to the following formula. 实 :

[0091] (Formula 3)

[0092] Wherein, Ud and Uq represent the current direct-axis voltage and quadrature-axis voltage of the motor under test, respectively. The current direct-axis voltage and quadrature-axis voltage of the motor under test are output through the current regulator inside the controller of the motor under test. The PI regulator is also located inside the controller.

[0093] In an optional embodiment of the present invention, such as Figure 4 As shown, after step S23, the following steps are performed:

[0094] S24: Function fitting step: Under the rated voltage of the motor under test, the calibrated direct-axis current Id and calibrated quadrature-axis current Iq at each torque point of the motor under test, as well as the calibrated direct-axis current Id and calibrated quadrature-axis current Iq at each calibrated speed point of the motor under test, are fitted to obtain a fitting function based on a preset linear fitting method. The fitting function uses the torque and speed of the motor under test as independent variables and the calibrated direct-axis current Id and calibrated quadrature-axis current Iq of the motor under test as dependent variables.

[0095] In this embodiment, a fitting function relating speed, torque, and current is obtained by linearly fitting the data calibrated under the current rated voltage. This facilitates the control of the motor under test and allows for the rapid determination of the calibration direct-axis current Id and calibration quadrature-axis current Iq of the motor under test when the speed and torque are known. In specific implementation, the linear fitting method is a bilinear interpolation method. Using bilinear interpolation achieves linear fitting between various variables, and the fitting process is relatively simple, effectively improving calibration efficiency.

[0096] In an optional embodiment of the present invention, such as Figure 4 As shown, after step S24, the following steps are performed:

[0097] S25: The relationship table generation step involves calculating a relationship table of the motor's speed, torque, calibrated direct-axis current Id, and calibrated quadrature-axis current Iq under different bus voltages based on pre-stored correspondences between the bus voltage and speed of the motor under test and the fitting function; and

[0098] S26: Relationship table correction step, which involves actually verifying the corresponding relationship table to correct each variable in the corresponding relationship table.

[0099] In this embodiment, the correspondence between the bus voltage and speed of the motor under test can be used to quickly obtain the correspondence table of speed, torque calibration direct-axis current Id, and calibration quadrature-axis current Iq under different bus voltages, which facilitates the control of the motor under test under different bus voltages. The host computer of the test bench can send torque commands, and the calibration torque point corresponding to the correspondence table can be corrected according to the torque recording error fed back by the bench to compensate for the torque error caused by the fitting function, thereby improving the calibration accuracy.

[0100] In practical implementation, MATLAB or Python can be used to fit the relationship function between speed, torque, and current. Using the bilinear interpolation method in MATLAB, the fitted function can be expressed as:

[0101] Function1=fit([x, y], z, 'linearinterp') (Formula 4)

[0102] Where x is the rotational speed, y is the torque, z is the D / Q axis current, linearinterp is the fitting method (bilinear interpolation), and Function1 is the fitting function. By inputting the rotational speed and torque parameters, the fitted D / Q axis current can be obtained.

[0103] Furthermore, the relationship between the bus voltage and speed of the tested motor can be expressed as:

[0104] (Formula 5)

[0105] Among them, Speed Cal and Udc Cal These represent the rated speed and rated voltage, respectively. Tab and Udc Tab The actual input speed and the actual input bus voltage are respectively.

[0106] In an optional embodiment of the present invention, the rated speed range, rated power range, and rated bus voltage range of the motor under test are all determined by the external characteristic curve of the motor under test. In this embodiment, by determining the rated speed range, rated power range, and rated bus voltage range of the motor under test based on the external characteristic curve of the motor under test, accurate calibration ranges can be obtained accurately based on the actual parameters of the motor under test, which is beneficial to improving the accuracy of calibration.

[0107] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the spirit and scope of the claims. All of these forms are within the scope of protection of the present invention.

Claims

1. A method for maximum torque current ratio calibration of a permanent magnet synchronous motor, characterized in that, The method comprises the following steps: a power-on step of controlling a direct current power supply in a calibration device by an upper computer in the calibration device to power on a measured motor and an accompanying motor installed on the calibration device and to control the accompanying motor to maintain the rotating speed of the measured motor at a turning speed of the measured motor, the upper computer pre-storing a calibration torque range of the measured motor; a initialization step of setting a current vector angle θ of the measured motor as a predetermined starting vector angle by the upper computer and gradually increasing a target current Is of the measured motor by the upper computer until the torque of the measured motor reaches a zero torque point of the calibration torque range and recording the target current Is at this time as a starting current value; a calibration step of alternately and cyclically adjusting the target current Is and the current vector angle θ of the measured motor by the upper computer, in each alternately and cyclically adjusting period, first increasing the target current Is from the starting current value to make the torque of the measured motor reach a next calibration torque point of the calibration torque range, and then adjusting the current vector angle θ of the measured motor from the starting vector angle until the torque of the measured motor is maximum, when each alternately and cyclically adjusting period is completed, updating the starting current value with the current target current Is and updating the starting vector angle with the current current vector angle θ, and taking the current target current Is and the current current vector angle θ as a calibration peak current and a calibration current vector angle of a current calibration torque point respectively; and a direct and alternating axis current calculation step of calculating calibration direct axis currents Id and calibration alternating axis currents Iq of each calibration torque point in the calibration torque range according to the corresponding relationship between the calibration direct axis currents Id and the calibration alternating axis currents Iq of the measured motor and the calibration peak current and the current vector angle θ by the upper computer, thereby completing the maximum torque current ratio calibration of the measured motor.

2. The maximum torque current ratio mapping method of a permanent magnet synchronous motor according to claim 1, wherein, From the second alternately and cyclically adjusting period, the adjusting increment of the target current Is in the last alternately and cyclically adjusting period is taken as an adjusting step size of the current alternately and cyclically adjusting period when the target current Is is adjusted.

3. The maximum torque current ratio mapping method of a permanent magnet synchronous motor according to claim 1 or 2, characterized in that, From the second alternately and cyclically adjusting period, the adjusting increment of the current vector angle θ in the last alternately and cyclically adjusting period is first increased, then the current vector angle θ of the measured motor is adjusted by a preset unit adjusting size, then it is judged whether the torque of the measured motor is increased, when it is judged that the torque of the measured motor is increased, the current vector angle θ of the measured motor is continuously increased according to the unit adjusting size until the torque of the measured motor is unchanged, otherwise, the current vector angle θ of the measured motor is gradually decreased according to the unit adjusting size until the torque of the measured motor is unchanged.

4. The maximum torque current ratio mapping method of a permanent magnet synchronous motor according to claim 1, wherein, The calibration torque range of the measured motor is determined by an external characteristic curve of the measured motor.

5. A calibration device for maximum torque current ratio calibration of a permanent magnet synchronous motor, comprising: a test bench for installing a measured motor thereon; an accompanying motor for interfacing with the measured motor to maintain the rotating speed of the measured motor at a turning speed of the measured motor; A direct current power supply is connected to the measured motor and the auxiliary motor respectively, and is used to power on the measured motor and the auxiliary motor respectively. A host computer is connected to the measured motor and the auxiliary motor respectively, and is used to pre-store the calibration torque range of the measured motor, and to correspondingly control the running state of the measured motor and the auxiliary motor, and to process the data collected in the calibration process. The host computer comprises: A power-on control module is used to control the direct current power supply to power on the measured motor and the auxiliary motor installed on the calibration device, and to control the auxiliary motor to maintain the rotating speed of the measured motor at the turning speed of the measured motor, and the host computer pre-stores the calibration torque range of the measured motor. An initialization module is used to set the current vector angle θ of the measured motor to a predetermined starting vector angle, and to gradually increase the target current Is of the measured motor until the torque of the measured motor reaches the zero torque point of the calibration torque range, and to record the target current Is at this time as the starting current value. A calibration module is used to alternately adjust the target current Is and the current vector angle θ of the measured motor, and in each alternately adjustment cycle, the target current Is is first increased from the starting current value to make the torque of the measured motor reach the next calibration torque point of the calibration torque range, and then the current vector angle θ of the measured motor is adjusted from the starting vector angle until the torque of the measured motor is maximum, and when each alternately adjustment cycle is completed, the starting current value is updated with the current target current Is, and the starting vector angle is updated with the current current vector angle θ, and the current target current Is and the current current vector angle θ are respectively taken as the calibration peak current and the calibration current vector angle of the current calibration torque point. A direct- and quadrature-axis current calculation module is used to calculate the calibration direct-axis current Id and the calibration quadrature-axis current Iq of each calibration torque point in the calibration torque range according to the corresponding relationship between the calibration direct-axis current Id and the calibration quadrature-axis current Iq of the measured motor and the calibration peak current and the current vector angle θ, so as to complete the maximum torque current ratio calibration of the measured motor.

6. A method of calibrating a permanent magnet synchronous motor, characterized in that, The method comprises: The maximum torque current ratio calibration method of any one of claims 1-4 is used to complete the maximum torque current ratio calibration of the measured motor; and The maximum torque current ratio calibration of the measured motor is used to complete the field weakening calibration of the measured motor.

7. The permanent magnet synchronous motor calibration method of claim 6, wherein, The host computer further pre-stores the calibration rotating speed range, the calibration power range and the calibration bus voltage range of the measured motor, and the maximum torque current ratio calibration of the measured motor is used to complete the field weakening calibration of the measured motor, which specifically comprises: A starting amount determination step is used to determine the starting direct-axis current and the starting quadrature-axis current of the calibration rotating speed point of the measured motor according to the maximum torque current ratio calibration of the measured motor. The step value determination process involves gradually increasing the speed of the motor under test via the host computer until the speed reaches the first calibrated speed point within the calibrated speed range. Based on the current direct-axis voltage Ud and quadrature-axis voltage Uq of the motor under test, the actual phase voltage U of the motor under test is calculated. 实 Based on the calibration bus voltage range, determine the peak phase voltage Usmax at the current calibration speed point of the motor under test, and compare it with the actual phase voltage U. 实 And the peak phase voltage Usmax, when the actual phase voltage U 实 When the actual phase voltage U is greater than the peak phase voltage Usmax, the actual phase voltage U 实 The difference between the phase voltage peak value Usmax and the actual power P of the motor under test is input to the PI controller of the test bench to calculate the direct-axis current step value of the motor under test. 实 Based on the calibrated power range, determine the target power P of the motor under test at the current calibrated speed point. 目 Compare the actual power P 实 and target power P 目 The actual power P 实 With target power P 目 The difference is input to the PI controller to calculate the quadrature-axis current step value of the motor under test. Based on the direct-axis current step value and the quadrature-axis current step value, the initial direct-axis current and the initial quadrature-axis current are corrected accordingly. The corrected initial direct-axis current and the initial quadrature-axis current are used as the calibration direct-axis current Id and the calibration quadrature-axis current Iq at the current calibration speed point; and A rotating speed calibration cycle step is used to cyclically execute the step of determining the step value until the calibration direct-axis current Id and the calibration quadrature-axis current Iq corresponding to each calibration rotating speed point are obtained.

8. The permanent magnet synchronous motor calibration method of claim 7, wherein, The following steps are further performed after the rotating speed calibration cycle step: a function fitting step of fitting the rated direct-axis current Id and the rated quadrature-axis current Iq of each of the calibration torque points of the measured motor and the rated direct-axis current Id and the rated quadrature-axis current Iq of each of the calibration speed points of the measured motor based on a preset linear fitting method to obtain a fitting function with torque and speed of the measured motor as independent variables and the rated direct-axis current Id and the rated quadrature-axis current Iq of the measured motor as dependent variables.

9. The permanent magnet synchronous motor calibration method of claim 8, wherein, After the function fitting step, the following steps are further performed: a relationship table generating step of calculating and obtaining a corresponding relationship table of speed, torque, rated direct-axis current Id and rated quadrature-axis current Iq of the measured motor under different bus voltages based on a pre-stored corresponding relationship formula of bus voltage and speed of the measured motor and the fitting function; and a relationship table correcting step of actually verifying the corresponding relationship table to correct each variable in the corresponding relationship table.

10. The permanent magnet synchronous motor calibration method of claim 7, wherein, The calibration speed interval, the calibration power interval and the calibration bus voltage interval of the measured motor are determined by the external characteristic curve of the measured motor.

Images