Implementation of cascaded H-bridge multilevel inverter for liquid food sterilization using pulsed electric field

This paper presents on evaluating a performance of Cascaded H-bridge Multilevel Inverter (CHMI) pulsed power supply, which can produce high-voltage output pulses and electric field strength for effective inactivation of microbes in liquid food sterilization process. The unique feature of the CHMI allows the system to produce bipolar square wave pulses with less power consumption and high stability compared to an exponential decay pulse (EDP) and oscillatory decay pulse (ODP) in liquid food sterilization. The CHMI pulsed power supply can achieving high output voltage without using a transformer while fulfilling the requirements specification for sterilizing an identified liquid food. This in turn can reduce the power losses due to omission of winding coil as well as reduce cost. The experimental results on the 7-level CHMI indicate that, output voltage and electric field strength up of 2.0 kV_p-p and 10 kV/cm respectively have been produced with both values meeting the pulse specifications for liquid food sterilization applications particularly for inactivation of Saccharomyces cerevisiae in orange juice.