Novel position sensorless starting method of BLDC motor for reciprocating compressor

The magnitude of output torque in a BLDC (brushless DC) motor depends on torque angle so that the exact initial position of rotor is essentially required for good starting performance. This paper describes starting performance for smooth starting in position sensorless BLDC motor drives for reciprocating compressor of refrigerator. In addition, position of rotor is determined from current response characteristics at align mode and level of the measured phase currents at the open-loop acceleration mode. The experimental results have suggested the effectiveness of starting method as starting load variations of reciprocating compressor.