LCC Resonant Converter Operating under Discontinuous Resonant Current Mode in High Voltage, High Power and High Frequency Applications

The full-bridge series-parallel resonant converters (also known as LCC resonant converters) with capacitive output filter is evaluated in high output voltage (>50 kV), high power (>50 kW) and high frequency (20 kHz) ESP (Electrostatic Precipitator) power supply applications. By using the leakage inductance and the winding capacitance of the transformer as the resonant elements only an additional series resonant capacitor is needed to form the LCC topology. ZCS turn-on and ZVZCS turn-off of the power switches are achieved by adopting the DCM (discontinuous current mode) control method. The concept of critical load is introduced as a key parameter to aid the circuit design. A prototype has been built to verify the operation principle of the circuit. Experimental results are given.