Single Current Sensing for Brushless DC Drives: a Fully Digital Solution

This paper presents a simple and effective solution about torque current reconstruction in Brushless DC Motor control drives for lift door automation. In particular a fully digital scheme is presented, based on a new generation DSP requiring only a few passive components for current measurements, this allows torque current reconstruction also in case of complementary switching modulation strategy by using a single current sensor in the dc link. Continuous current offset compensation is performed by suitable sampling strategy and minimum pulse cancellation effects can be easily addressed. The proposed torque current reconstruction has been tested in a closed loop speed control with both sensored and sensorless drive operation.