Narrow pulsed electric field generator using forward / flyback hybrid converters for liquid food processing

This paper presents a high pulsed electric field generator for microbial inhibition of liquid food in continuous treatment applications. The proposed pulsed electric field generator adopts forward/flyback hybrid converters to achieve a bidirectional narrow pulse voltage output. With this circuit structure, the proposed one can reduce voltage stresses of output diodes and switches in secondary winding of transformer, resulting in a lower cost. It can also decrease voltage variation of components at turn-on and turn-off transitions to avoid noise interference. Furthermore, the proposed generator uses two active clamp circuits to recover the energy trapped in the leakage inductance of transformer with high turns ratio, while a half-bridge inverter is adopted to drive piezoelectric devices for clearing the inhibiting electrodes. To simplify circuit structure of the proposed system, a synchronous switch technique is used to integrate switches between active clamp flyback/forward hybrid converters and half-bridge inverter to increase conversion efficiency and reduce volume, size, weight and cost. Finally, a prototype with maximum output electric field intensity of 50 kV/cm and repetitive rate of 6 Hz has been implemented to prove the feasibility of the proposed pulsed electric field generator.