An active damping control method for a Bi-directional flyback converter driving a piezoelectric transducer

This paper presents a novel active damping control method for the driving circuit of a piezoelectric transducer (PT) applied in a distance measurement system. Since the vibration of the PT cannot come to a halt instantly after the driving circuit stops driving it, the minimum detectable length in the system with a single PT is restricted. By applying active damping, the transition time can be reduced. Conventionally, a peak detection circuit is needed to realize the active damping control. However, with the proposed control, the phase of the vibration can be known from the driving signal, and the active damping control can be realized without any sensing circuits. The proposed control method is verified with a bi-directional flyback converter. The experimental results show that the amplitude of terminal voltage of the PT can be reduced to one-fourth of the value with the conventional passive damping.