Design of an LLC resonant converter for EDM applications

The design of the LLC resonant converter is presented for use in electrical discharge machine (EDM) applications. This converter is designed to operate with a dc input voltage and will output controlled dc voltages during both the striking and arc conditions of the EDM process. The method employed magnitude and frequency control to enable the converter to operate at zero voltage and zero current transitions. A voltage constraint on the resonant capacitor will be implemented to address a common source of failure mode that is normally neglected in resonant converters. The design will inherently protect the resonant capacitor from overvoltage at different loading conditions during machining. The normalized capacitor voltage will be included in the factors considered when designing the resonant tank. A design example and simulation waveforms are presented to validate the design.