Interleaved four-phase buck-based current source with center-tapped energy-recovery scheme for electrical discharge machining

This paper proposes a center-tapped energy-recovery scheme used in the interleaved four-phase buck-based current source in continuous conduction mode (CCM) for electrical discharge machining (EDM). A pulse machining current with high slew rate is required for the EDM. Using the interleaving technique, the output current slew rate of the buck-based current source can be improved because of the paralleled inductors at the start of discharge. The proposed center-tapped energy-recovery scheme provides a major path for the inductor to release its stored energy to avoid high voltage stress in the output terminal when the gap is in the high-impedance state. The energy stored in the inductor is recovered to the input capacitor, and can be reused for machining. The experimental results are provided as the verification of the high output current slew rate and the energy recovery when the gap is in high-impedance state.