A variable speed drive circuit topology for feeding a 3-phase inverter bridge with a combined current and voltage DC link

This paper describes the operation of a 3-phase drive that supplies a 3-phase inverter bridge with a combined current and voltage DC link. During steady state conditions, the DC rail voltage is controlled at levels above the rectified supply voltage. The high switching frequencies of the inverter bridge can be used to lower the size of the DC link capacitors and inductors. During output short-circuit fault conditions, the DC-link capacitor can be automatically disconnected and the rate of rise of fault currents can be restricted by the DC link inductor. Protection is obtained against short circuit faults such as line-line and line to supply neutral faults. Simulation results are used to illustrate the drive operation