A novel soft switching ZVS, sinusoidal input boundary current mode control of 6-switch three phase 2-level boost rectifier for active and active + reactive power generation

Recent advancements in semiconductor technology and the commercial availability of low on resistance and parasitic capacitors wide bandgap devices (SiC & GaN) has led power electronics systems to achieve efficiency as high as 99% for three phase boost PFC rectifier systems. However, this high efficiency is attainable only for rectifiers running at low switching frequencies (<70 kHz) as these converters operate in hard switching continuous conduction mode (CCM). Turn-on losses become dominant for high switching frequency operation with CCM. The trend for increasing switching frequency is driven by the fact that high switching frequency operation leads to significant reduction in filter size but high switching frequency operation is only feasible with soft switching ZVS turn-on control. Critical conduction mode (CRM) with ZVS turn-on has considerably high efficiency for single phase boost PFC at very high switching frequencies (>1 MHz). However, conventional boundary conduction mode (BCM)/CRM for three phase rectifier systems, does not generate sinusoidal average input current. A Zero Voltage Switching (ZVS) BCM control with sinusoidal input current for three phase 2-level converter is presented in this paper. This paper covers unity power factor (u.p.f.) operation, active + reactive power and also purely reactive power generation cases. The control scheme is presented in detail and ZVS turn-on operation is also discussed. The simulation and experimental results are discussed in the end. For a 1.2 KW converter, power density achieved by >500 kHz switching frequency operation is similar to 80 W/m(3) and with soft switching, 99 % efficiency is maintained.