Three-Phase Bidirectional-Flyback Differential-Inverter for Synchronous Electrostatic Machines

Abstract

Synchronous electrostatic machines can deliver extremely low loss while holding rated torque, with recent direct drive demonstrations of 0.625 W/Nm holding torque. Until now, power electronics topologies have focused on the support of wide torque-speed operation of these machines, resulting in drive systems that are suboptimal for applications largely operating at stall. Leveraging the ability of these machines to support dc-voltages without saturation, bidirectional flyback DC-DC converters are arranged to form a compact three-phase differential-inverter from a line to line terminal perspective. The arrangement is analytically modelled and analyzed for the position and hold application. This topology provides large voltage-gain and reduced component count eliminating isolated gate drivers. Utilized in discontinuous conduction mode at high frequencies, the topology has reduced switching loss and reduced magnetic component sizes. These attributes provide a suitable roadmap for drive integration with the machine. For comparison to the analytical model the converter is simulated in PLECS and Vdq0 controller is utilized for charge-oriented control.