Digital Control of a High-Voltage (2.5 kV) Bidirectional DC--DC Flyback Converter for Driving a Capacitive Incremental Actuator

This paper presents a digital control technique to achieve valley switching in a bidirectional flyback converter used to drive a dielectric electroactive polymer-based capacitive incremental actuator. This paper also provides the design of a low input voltage (24 V) and variable high output voltage (0-2.5 kV) bidirectional dc-dc flyback converter for driving a capacitive incremental actuator. The incremental actuator consists of three electrically isolated mechanically connected capacitive actuators. It requires three high-voltage (HV) (2-2.5 kV) bidirectional dc-dc converters to accomplish the incremental motion by charging and discharging the capacitive actuators. The bidirectional flyback converter employs a digital controller to improve the efficiency and charge/discharge speed using the valley switching technique during both charge and discharge processes, without the need to sense signals on the output HV side. Experimental results verifying the bidirectional operation of a HV flyback converter are presented using a 3-kV polypropylene-film capacitor as the load. The energy-loss distributions of the converter are presented when 4- and 4.5-kV HV mosfets are used on HV side. The flyback prototype with a 4 kV mosfet demonstrated 89% charge energy efficiency to charge the capacitive load from 0 V to 2.5 kV, and 84% discharge energy efficiency to discharge it from 2.5 kV to 0 V.