Improvement of burst-mode controlled piezoelectric transformers

The burst-mode operation was adopted in piezoelectric transformer based converter for two major purposes: 1. to make the regulation in DC-DC converter and 2. to make the dimming control in the backlight inverter. The burst mode control can fix the switching frequency of the converter as well as keep the good efficiency at the light load condition. However, the piezoelectric transformer cannot stop instantly in the burst mode in practice. The delay derived from piezoelectric transformers influences the accuracy of the regulation. This research proposes a control strategy to make the piezoelectric transformer can stop more quickly so as to enhance the accuracy of burst mode control. The proposed method does not add extra component but only modified the control signal of the burst-mode driving circuit. The proposed control strategy is verified by the experiment.