Control method for compensating location torque of permanent-magnet motor by injecting current harmonics

Abstract

The invention discloses a control method for compensating location torque of permanent-magnet motor by injecting current harmonics; in the method, harmonic current is injected to interact with the fundamental wave permanent magnetic potential to generate an additional torque component, so that the additional torque can be equal to the amplitude of the fundamental wave and the ultra-harmonics component in the directional torque and the phase positions thereof are opposite and can be offset, thus achieving the aim of compensating the location torque. In the method, firstly harmonic analysis is carried out on the location torque of the permanent-magnet motor by using finite element simulation result or observed data and adopting the Fourier series approximation approaching method; secondly the aero load counter electromotive force of the permanent-magnet motor is analyzed and the corresponding mathematical expression is written out; and finally the injected harmonic current is worked out according to the principle that additional torque and location torque can offset each other.

Description

Technical field [0001] The invention is a control technology for compensating the positioning torque of a permanent magnet motor by injecting current harmonics, and belongs to the technical field of motor drive and control. Background technique [0002] With the continuous improvement of the cost performance of the rare earth permanent magnet material neodymium iron boron (NdFeB), permanent magnet motors are widely used in more and more industrial drive and servo control fields due to their small size, high efficiency, and good dynamic response characteristics. However, in a permanent magnet motor, the permanent magnet interacts with the slotted armature core to generate a positioning torque, which causes vibration and noise during the operation of the motor. The existence of the positioning torque affects the low-speed performance of the motor in the speed control system and in the position control system. High-precision positioning. [0003] Regarding the method of weakening an...

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Problems solved by technology

In general, it can be classified into two categories: one is to study the methods of weakening the positioning torque of permanent magnet motors starting from the design of the motor body, such as including stator / rotor skewed slots or oblique poles, magnetic pole shape optimization, fractional slot structure, pole Combination optimization of arc coefficients, rotor segmentation, asymmetric placement of permanent magnets, stator / rotor opening auxiliary slots, optimized design of stator slot width, matching of different slot widths, and optimized design of core shape, etc., but due to many limitations in various aspects, Constrained by the structure of different types of motors, the degree of reduction of the positioning torque is limited. In addition, this type of method for the motor body will not only weaken the positioning torque, but also affect the no-load back electromotive force and power output capability of the motor. The manufacturing cost has certain limitations in the actual industrialization process; the second type of method is to compensate the positioning torque of the motor through the control strategy under the condition that the motor body cannot be improved after the motor has been manufactured, thereby improving its output performance

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