Feedforward current control system design for efficient drive method of small-sized brushless DC motor

In the low inductance and small-sized brushless DC motor, the conventional PWM driving method makes relatively large PWM loss because of an unintended directional transition current caused by ordinary complementary switching in the half-bridge circuits. We have proposed an idea of the efficient drive method and feedforward current control system in which the bridge circuits are driven with non-complementary switching, based on the simplified circuit analysis. In the proposed drive and current control system, the driver circuits and the micro controller can be a usual existing product, in which only control software is replaced, without additional electronic components. In this paper, we report the detail design of the feedforward control system with proposed efficient drive method. And the effectiveness of proposed method is also discussed based on the detail calculation and experiments.