Permanent magnet synchronous motor anti-demagnetization control method

Abstract

The invention discloses a permanent magnet synchronous motor anti-demagnetization control method which comprises the following steps: first, detecting motor speed and motor phase current, second, if the motor speed is less than the maximum speed of revolution of track before detect percent (TBD%), a system becomes invalid and detects the motor phase current to be over a threshold value, and a controller controls six switching tubes of a three phase permanent magnet synchronous motor to open, third, after n plurality of seconds, entering a next three insulated gate bipolar transistor (IGBT) short circuit module of the three phase permanent magnet synchronous motor, three switching tubes on the three phase permanent magnet synchronous motor keep opening, and the next three switching tubes of the three phase permanent magnet synchronous motor are controlled. According to the permanent magnet synchronous motor anti-demagnetization control method, when normal rotate speed operation of the motor is shifted into the next three IGBT short circuit pattern of the three phase permanent magnet synchronous, an instantaneous peak value large current produced according to an original method is reduced, and the risk of motor permanent magnet steel demagnetization is prevented or reduced. So when the motor is designed, magnetic circuit design can be carried out based on the reduced instantaneous peak value current, magnet steel with low coercivity is chosen, rare earth content is reduced, and the purpose of reducing cost is achieved.

Description

technical field [0001] The invention relates to a failure response control method for reducing the demagnetization rate of motor magnetic steel, and is especially suitable for permanent magnet synchronous motors used in new energy vehicles. Background technique [0002] In the design of permanent magnet synchronous motor (PMSM) for new energy vehicles, it is necessary to consider the risk of demagnetization of the permanent magnet steel in the motor under some harsh driving conditions. The higher the intrinsic coercivity (Hcj) of the magnet, the stronger the corresponding anti-demagnetization ability, but at the same time, due to the increase of the content of rare earth dysprosium in the magnet, the cost is correspondingly higher. [0003] The instantaneous peak current (Ipeak) that may occur in the motor under severe working conditions (such as mode switching) is one of the key factors affecting the demagnetization of the magnetic steel. [0004] When a failure occurs, th...

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Problems solved by technology

[0006] The disadvantage of this method is that if the vehicle runs at high speed when a failure occurs, the motor speed will be relatively high

[0008] The disadvantage of this method is that: when the mode is switched, an instantaneous peak current impact will be generated in the motor winding, and the current amplitude may exceed 2 times the maximum phase current, which may cause demagnetization of the permanent magnet steel and decrease the performance of the motor

If the intrinsic coercive force of the permanent magnet steel is small, the magnet will demagnetize, and the performance of the motor will be greatly reduced; Under the situation of sharply rising rare earth prices, the total cost of motors will increase significantly, which will inevitably affect the prices of hybrid electric vehicles and pure electric vehicles, and seriously hinder the popularization of new energy vehicles.

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