Permanent magnet motor magnetic pole position detection method

Abstract

The invention discloses a method for detecting the position of a magnetic pole of a permanent magnet motor. The method comprises the following steps: 101) identifying the position of the magnetic pole: respectively injecting two orthogonal high-frequency square wave voltage signals into an alpha axis and a beta axis, demodulating the high-frequency response current signals on the alpha axis and the beta axis, and identifying the position of a rotor pole; 102) magnetic pole polarity identification: after magnetic pole position identification is completed, keeping high-frequency square wave voltage signal injection unchanged, and injecting a low-frequency sinusoidal current signal of a period into a d axis, so the magnitude of high-frequency response current is changed. The polarity of the magnetic pole is identified by comparing the positive and negative peak values of the low-frequency sinusoidal current signal and the high-frequency response current signal at the positive and negativepeak values. According to the detection method, the rotor is not twisted, the detection is accurate, and the response speed is high.

Description

[technical field] [0001] The invention relates to a permanent magnet motor, in particular to a detection method for the magnetic pole position of the permanent magnet motor. [Background technique] [0002] Permanent magnet motors have been widely used because of their high efficiency, high torque density, low motor operating noise, and excellent control performance. Compared with the traditional electric excitation motor, its working principle is basically the same, the difference is that it abandons the excitation coil, but uses a permanent magnet with high magnetic flux density for excitation, which simplifies the structure of the motor body and further improves the working efficiency of the motor. At the same time, the electronic commutation circuit is used to replace the commutator circuit and brushes, which avoids the shortcomings of commutation sparks and commutation losses; compared with asynchronous motors, permanent magnet motors have no reactive excitation current ...

AI Technical Summary

Problems solved by technology

The conventional method without using sensors is to inject a DC current of known magnitude and direction for a period of time to generate a fixed magnetic field, forcing the rotor to rotate to the position where the two flux linkages are in the same direction, and then start running after stabilization. The method will cause a large twist of the rotor during the positioning process. In some cases, it is forbidden to reverse the motor when starting.

[0004] There is also a method for the initial magnetic pole position of the motor is to inject a high-frequency square wave voltage signal into the permanent magnet motor, and then obtain the magnetic pole position through the relationship between the high-frequency response current in the winding and the magnetic pole position. This method is more obvious for the permanent magnet motor. Effective, but it is difficult to detect accurately for permanent magnet motors whose salient pole effect is not obvious

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