Sensorless control of the brushless DC motors based on TMS320F2812

A new sensorless control strategy for the brushless DC(BLDC) motors is proposed in this paper. The technique builds a rotor position-related flux function, which is independent of the speed. By observing the flux function, the information of rotor position and commutation can be obtained. Because the function is not speed-related, this sensorless control process can be used in a wider range of speed and improve the motor startup performance. Then an experimental test bed that includes a 1.2kw BLDC motor, drivers and a TMS320F2812DSP controller is built. At the starting process of the motor, the controller adopts a strategy that combines pre-position method and frequency, voltage boost method. After startup, the G function gives the commutation signal. The experimental result indicates, the proposed control strategy can make the motor achieve a smooth starting-up and stable phase commutation.