Narrow pulsed voltage generator for liquid food sterilization

This paper first reviews mechanism and waveform consideration for liquid food sterilization, and then presents how to generate bipolar narrow pulses. In this research, a bidirectional flyback converter with energy recovery circuits is proposed to generate bipolar narrow pulsed electric fields for liquid food sterilization, which includes sterilization of drinking water, alcoholic beverages, fruit juice, etc. Since in the converter, leakage inductance is around 1% of the magnetizing inductance, capacitors are used to resonate with the leakage inductor to recover the trapped energy and to reduce switching loss, improving efficiency about 13%. In addition, the energy recovery capacitor can reduce voltage stress significantly. Experimental results obtained from a prototype with the output of ±6 kV ±20 kV, depending on loads, and peak power of 250 kW have confirmed these discussions.