A device and method for improving the starting ability of an asynchronous starting permanent magnet motor

Abstract

The invention discloses a device for improving the starting capability of an asynchronous starting permanent magnet motor, comprising an asynchronous starting permanent magnet motor, a manual triple switch KA, a contactor KM, a control circuit and an encoder installed on the rotor of the asynchronous starting permanent magnet motor. The input terminal of the rectifier circuit and the input terminal of the power supply voltage synchronous signal acquisition circuit are connected between the main triple normally open contact KM1 and the manual triple switch KA, the output signal of the power supply voltage synchronous signal acquisition circuit is sent to the control unit, The encoder sends the initial position signal of the magnetic pole to the control unit, the output terminal of the control unit is connected to the base of the control transistor T, the collector of the encoder is connected to the coil of the contactor KM, and the auxiliary normally open contact KM2 is connected in parallel between the collector and the emitter of the control transistor T. The invention improves the starting capability, reduces the starting current, and realizes the smooth starting under complex environments such as heavy load, load fluctuation and the like.

Description

Technical field [0001] The invention relates to the field of asynchronous starting permanent magnet motors, and in particular to a device for improving the starting ability of asynchronous starting permanent magnet motors. Background technique [0002] The asynchronous start permanent magnet motor adds a rotor squirrel cage winding to the permanent magnet synchronous motor, which is used to improve the self-starting ability of the motor under power frequency power supply. At the same time, it achieves high efficiency and high power factor in synchronous operation. Pumping units, textile machinery and other fields have been successfully applied. [0003] However, the on-load starting capacity of the asynchronous start permanent magnet motor under the power frequency power supply is insufficient, the main reasons are as follows: (1) The permanent magnet on the rotor will generate the dynamic braking torque during the starting process, which will reduce the starting torque; (2) ) The...

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Problems solved by technology

[0003] However, under the condition of power frequency power supply, the on-load starting capability of the asynchronous starter permanent magnet motor is insufficient. The main reasons are as follows: (1) The permanent magnet on the rotor will generate generating braking torque during the starting process, which will reduce the starting torque; (2) ) The squirrel cage windings on the rotor and the permanent magnets compete in the design space, and their starting performance is weaker than that of induction motors of the same specification; (3) The starting torque ripple is large, and the starting conditions change (such as starting time, load fluctuations, etc.) prone to failure to start

[0004] Patents CN201310062586X, CN2011201861917, and CN2012100312343 propose devices for improving the starting capability of asynchronous starter permanent magnet motors, which use power electronically controlled soft starters to start, and are powered by power frequency alternating current during operation, which has the following disadvantages: (1) The system cost is high and requires Dedicated control unit and power electronic device; (2) The opening and closing of power electronic devices produces harmonics that pollute the power grid; (3) There is a secondary impact when switching to direct power frequency AC power supply after starting

[0005] Patent CN201410139036.8 improves the starting performance and steady-state performance by improving the rotor structure, but the processing of the motor product is complicated and the manufacturing cost is high

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