A Class-E-Based AC-DC converter for PFC applications

Abstract

Connection of nonlinear utility load har increased through resent years and is expected to continue increasing. Nonlinear utility load injects harmonic content into the grid and reduces voltage quality for nearby consumers. To limit harmonic content from nonlinear load, the International Electrotechnical Commission requires power supplies to be designed according to IEC 61000-3-2. Fulfilling this standard for nonlinear load is done by power factor correction (PFC).

Conventionally, pulse width modulation (PWM) converter has been used for PFC converters as they provide high efficiency with a simple control technic. However, as PWM converters switch by hard-switching, that limits the switching frequency through switching loss and generates EMI, resonant converters has become more attractive. Resonant converters operate at soft-switching where the voltage across and/ or current through is zero in the switching moment. This reduces switching loss and EMI, and allow for high switching frequency. High switching frequency is desired as it enables high power density.

Through this thesis, two resonant converters using high switching frequency has been proposed. These converters are based on a Class-E converter as it has low noise and high efficiency when switching at high frequency. The thesis includes a mathematical model for both converts, simulation and experimental testing result. Result from testing differs from calculated and simulated values, and troubleshooting for one of the converters has been conducted. Through troubleshooting and a second test with changed parameters, the performance of the converter increased compared to the first test. Due to lack of time, the debugging process was not completed and will be a part of future work.