Improvement of efficiency and vibration noise characteristics depending on excitation waveform of a brushless DC motor

The 10poles-12-slots brushless DC motor is superior as AC servo motor by sine-wave excitation, but its characteristics like efficiency get worse by using as BLDC motor by square-wave excitation. However, 150-degree excitation which adjusted excitation angle and excitation phase can increase 3% of efficiency from general 120-degree excitation, and it can make phase current similar to sine wave. And then, square wave excitation which used hall sensors and counters is simple way of BLDC drives, and it needs less supply voltage than that to drive BLDC by sine-wave excitation. Therefore, we shows that 150degree square-wave excitation is suitable in high efficiency and simple BLDC drive.