Multi-phase Interleaved buck-Type Pulse Power Generator for Die-Sinking EDM

Abstract In the die-sinking electrical discharge machining (EDM), a large discharge energy for roughing (several hundred amperes with a few hundred microseconds) and a low discharge energy for finishing (a few amperes with tens to hundreds of nanoseconds) pose a challenge to the pulse power generator. This paper proposes a power-electronic-based pulse power generator, which adopts multi-phase interleaved buck converters as the main circuit, and a high output voltage circuit for gap breakdown. The multi-phase interleaved buck converters control the discharge current waveform to follow a given reference by high frequency switching mode operation, and the discharge current ripple is cancelled to a low value due to the interleaving control technology. The multi-phase operation is performed for rough machining, and a single-phase operation with high switching frequency and narrow discharge pulse is used in finish machining. As a result, one small volume generator can be placed near the discharge gap. At last, a prototype is used in real machining to compare the machining performance of different current waveforms.