Sensor less control of rotating machine

 In a permanent magnet brushless motor, the rotary position sensor senses the position of magnetic poles and the current is supplied to the coils (U,V,W) at an appropriate timing so that the attraction and repulsion necessary for driving force are generated from the magnetic poles.

 By the way, it is possible to estimate the position of each magnet pole by supplying a high-frequency signal to the motor's coils from the inverter for a short time. Using this technique, an electric motor can be built without using a rotary position sensor.

 Because complex high-speed computing using software is involved in this method, it is necessary to use a high-speed microcomputer or DSP (Digital Signal Processor).






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