An Improved Speed Governing Circuit for Brushless DC Motor

To enhance the reliability of motor, a new pulse width modulation (PWM) circuit for speed governing is designed via analyzing the speed governing principle of brushless DC motor (BLDCM) and improving the PWM circuit for traditional speed governing system of brush DC motor. This new circuit makes use of single supply to overcome the influence of asymmetric dual supply on speed governing pulse width. The experimental results show that the new circuit is of less parts, better controllability, higher precision, and stable output with loose supply voltage requirement. The improved speed governing circuit can be extensively applied to measurement, communication, power control and conversion, etc.