A method for automatic calibration of permanent magnet synchronous motor MTPA

Abstract

The present invention discloses a method for automatic calibration of a permanent magnet synchronous motor (MTPA). The method comprises: presetting a test bench speed via a computer; sending a command from the computer to a motor controller, which controls the motor on the test bench to rotate at the preset speed, wherein the motor's initial phase current Is is 0 and the initial current angle θ is 0; adjusting the motor's phase current Is until the true torque value fed back by a measuring device is the same as the target torque; adjusting the motor's current angle θ until the true torque value fed back by the measuring device is maximized; and if the true torque value is the same as the target torque, recording the phase current Is and current angle θ at the true torque value. The present invention solves the problem of requiring manual calibration, reduces the number of points of torque values corresponding to the recorded ID / IQ, eliminates fitting and on-test bench correction, and simplifies the calibration process.

Description

Technical Field

[0001] The present invention belongs to the field of testing of permanent magnet synchronous motors, and in particular relates to an automatic calibration method for a permanent magnet synchronous motor (MTPA). Background Art

[0002] Permanent magnet synchronous motors (PMSMs) are compact and highly efficient, making them widely used in applications such as electric vehicles. These motors primarily utilize vector control, transforming the stator current into two components, id / iq, in a rotating coordinate system. To ensure efficient control of PMSMs, a maximum torque-to-current (MTPA) curve is required to achieve maximum torque at minimum current.

[0003] Current methods for calibrating MTPA control include: 1. Online calculation, which calculates the ID / IQ values for different torques based on the motor current equation, torque equation, and inductance parameters. This requires a large amount of computation and places high demands on the processor chip. 2. Offline calculation, which obtains the ID / IQ values corresponding to the MTPA at different torques and writes them into a table in the software for use as a lookup table. This method offers excellent real-time performance, high controller accuracy, and low chip requirements, though it only increases storage space.

[0004] Traditional MTPA table calibration uses a fixed-step Id / Iq ratio to sweep the entire current limit circle, then fits the MTPA curve to the torque values corresponding to different Id / Iq ratios. A disadvantage is the need to manually record a large number of torque values corresponding to different Id / Iq ratios. Because these values are fitted, they require recalibration on the test bench. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a permanent magnet synchronous motor MTPA automatic calibration method to address the deficiencies of the above-mentioned prior art. This permanent magnet synchronous motor MTPA automatic calibration method solves the problem of requiring manual calibration, reduces the number of points of the torque values corresponding to the recorded id / iq, eliminates fitting and re-correction on the test bench, and simplifies the calibration process.

[0006] In order to achieve the above technical objectives, the technical solution adopted by the present invention is:

[0007] A permanent magnet synchronous motor MTPA automatic calibration method comprises the following steps:

[0008] Step 1: Connect the computer to the motor controller, and the motor controller to the motor on the test bench;

[0009] Step 2: Obtain the phase current Is and current angle θ under a certain target torque:

[0010] (2.1) Preset the speed of the test stand through the computer;

[0011] (2.2) The computer sends a command to the motor controller, which controls the motor on the frame to rotate at a preset speed, where the initial phase current Is of the motor is 0 and the initial current angle θ is 0;

[0012] (2.3) Adjust the motor phase current Is until the actual torque value fed back by the measuring device is the same as the target torque;

[0013] (2.4) Adjust the motor current angle θ until the true torque value fed back by the measuring device is the maximum;

[0014] (2.5) If the actual torque value is the same as the target torque, record the phase current Is and current angle θ under the actual torque value and execute step 3; if the actual torque value is different from the target torque, return to step (2.3);

[0015] Step 3: According to the method in step 2, obtain the phase current Is and current angle θ under all target torques;

[0016] Step 4: Calculate the id value and iq value under each target torque.

[0017] As a further improved technical solution of the present invention, the formula for calculating the id value and the iq value under each target torque is specifically:

[0018] id=-Is*sin(θ); iq=Is*cos(θ).

[0019] The beneficial effects of the present invention are:

[0020] The present invention provides an automatic calibration method for a permanent magnet synchronous motor (MTPA), which eliminates the need for manual calibration, reduces the number of points of torque values corresponding to the ID / IQ records, eliminates fitting and re-correction on a test bench, simplifies the calibration process, and greatly improves calibration efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a structural schematic diagram of the present invention.

[0022] Figure 2 It is a flow chart of the present invention. DETAILED DESCRIPTION

[0023] The specific embodiments of the present invention are further described below with reference to the accompanying drawings:

[0024] A permanent magnet synchronous motor MTPA automatic calibration method comprises the following steps:

[0025] Step 1: Connect the computer to the motor controller, connect the motor controller to the motor on the test bench; and connect the measuring device to the computer.

[0026] The computer is used to send instructions to the motor controller and obtain information from the measuring device. The motor controller is used to control the motor on the test bench according to the instructions sent by the computer. The measuring device is used to measure the output torque value of the motor on the test bench. Figure 2 The computer is also used to automatically store Is / θ below the target torque value and calculate the corresponding id / iq based on Is / θ.

[0027] Step 2: Obtain the phase current Is and current angle θ under a certain target torque:

[0028] (2.1) The test bench speed is preset by computer; the speed is based on the maximum speed of the motor without weak magnetic field.

[0029] (2.2) The computer sends a command to the motor controller, which controls the motor on the frame to rotate at a preset speed, where the initial phase current Is of the motor is 0 and the initial current angle θ is 0;

[0030] (2.3) Adjust the motor phase current Is until the actual torque value fed back by the measuring device is the same as the target torque;

[0031] (2.4) Adjust the motor current angle θ until the true torque value fed back by the measuring device is the maximum;

[0032] (2.5) If the actual torque value is the same as the target torque, record the phase current Is and current angle θ under the actual torque value and execute step 3; if the actual torque value is different from the target torque, return to step (2.3).

[0033] Step 3: According to the method in step 2, obtain the phase current Is and current angle θ under all target torques.

[0034] Step 4: Calculate the id value and iq value under each target torque.

[0035] The formula for calculating the id value and iq value under each target torque is specifically:

[0036] id=-Is*sin(θ); iq=Is*cos(θ).

[0037] The MTPA curve is an id / iq table corresponding to torque points of equal step lengths in control. The target torque of this embodiment is the torque points of equal step lengths required in the MTPA curve.

[0038] This embodiment provides an automatic calibration method for a permanent magnet synchronous motor (MTPA), which eliminates the need for manual calibration, reduces the number of points of torque values corresponding to the recorded ID / IQ, eliminates fitting and re-correction on the test bench, simplifies the calibration process, and greatly improves calibration efficiency.

[0039] The protection scope of the present invention includes but is not limited to the above embodiments. The protection scope of the present invention is based on the claims. Any replacement, deformation, and improvement of the technology that can be easily thought of by those skilled in the art fall within the protection scope of the present invention.

Claims

1. A method for automatic calibration of a permanent magnet synchronous motor (MTPA), characterized by: The steps include: Step 1: Connect the computer to the motor controller, and the motor controller to the motor on the test bench; Step 2: Obtain the phase current Is and current angle θ under a certain target torque: (2.1) The speed of the test bench is preset by the computer, and the speed is based on the maximum speed of the motor without field weakening; (2.2) The computer sends a command to the motor controller, which controls the motor on the frame to rotate at a preset speed, where the initial phase current Is of the motor is 0 and the initial current angle θ is 0; (2.3) Adjust the motor phase current Is until the actual torque value fed back by the measuring device is the same as the target torque; (2.4) Adjust the motor current angle θ until the true torque value fed back by the measuring device is the maximum; (2.5) If the actual torque value is the same as the target torque, record the phase current Is and current angle θ under the actual torque value and execute step 3; If the actual torque value is different from the target torque, return to step (2.3); Step 3: According to the method in step 2, obtain the phase current Is and current angle θ under all target torques; Step 4: Calculate the id value and iq value under each target torque.

2. The automatic calibration method for a permanent magnet synchronous motor (MTPA) according to claim 1, characterized in that: The formula for calculating the id value and iq value under each target torque is specifically: id=-Is*sin(θ); iq=Is*cos(θ).

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