Method and system for monitoring rotor excitation loss fault of permanent magnetic motor

Abstract

The embodiments of the present invention provide a method and system for monitoring the rotor excitation loss fault of a permanent magnetic motor. The method includes the following steps that: the actual port voltage of one or more detection coils disposed in a permanent magnet synchronous motor and the operating rotation speed of the permanent magnet synchronous motor are detected; the effectivevalue of a predetermined harmonic component in the actual port voltage of each of the detection coils is calculated; the on-line monitoring value of each detection coil is calculated according to theeffective value of the predetermined harmonic component in the actual port voltage of the corresponding detection coil; and the on-line monitoring value of each detection coil is compared with the alarm value of the corresponding detection coil, wherein the alarm value of the detection coil is corresponding to the operating rotation speed, so that the comparison result of each detection coil is obtained; and whether a rotor excitation loss fault occurs on the permanent magnetic motor is judged according to the comparison result of the one or more detection coils. The monitoring method providedby the invention has high sensitivity and reliability for the rotor excitation loss fault of the permanent magnetic synchronous motor.

Description

technical field [0001] The invention relates to the technical field of relay protection and on-line monitoring of main equipment in a power system, and more particularly relates to a method and system for monitoring a permanent magnet motor rotor demagnetization fault. Background technique [0002] Due to its advantages of high power density, high efficiency, high reliability and high torque, permanent magnet synchronous motors have been more and more widely used in various fields such as new energy power generation, electric vehicle drive, aerospace and rail transportation. . In permanent magnet synchronous motors, permanent magnets are necessary for the motor to function properly. However, in the case of improper motor design or permanent magnet manufacturing process, aging of permanent magnets, high operating temperature of the motor, mechanical vibration, external or internal faults of the motor, etc., the permanent magnets may be partially weakened or even completely d...

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Problems solved by technology

Although this method of judging loss-of-excitation faults based on specific harmonic currents has the advantages of simple and convenient signal acquisition, it has many limitations. The output of the frequency converter is not an ideal sine wave, but contains a large number of harmonics, which leads to a large number of harmonic components in the armature current. When the permanent magnet synchronous motor has a demagnetization fault, it is difficult to distinguish the harmonics in the armature current from the The fault is caused by the frequency converter, which brings difficulties to the fault diagnosis; (2) Under certain stator winding structures, when the motor loses the field of the rotor, no new harmonic components will be generated in the armature current, that is, there will be no Harmonic components unique to loss-of-excitation faults are generated, and it is impossible to judge whether the motor has a loss-of-excitation fault at this time

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