Design, Implementation, and Performance Analysis of Average and Hysteresis Current Controlled Non-Isolated Boost PFC for Induction Heating

The presence of a filtered diode rectifier in the power stage of an Induction heater (IH) inevitably lowers the power factor and distorts the input current waveform of the utility. This leads to reduced efficiency and interferes with the functioning of other line-connected equipment. This paper attempts to improve the input power factor and regulate the line current harmonics within electromagnetic compatibility (EMC) standards. In this work, a non-isolated boost converter is operated in continuous conduction mode (CCM) to provide a precise and ripple-free DC voltage to the series resonant inverter of an induction heating system. A two-loop controller is designed with an outer voltage loop for regulating the power and an inner current loop for shaping the input current. The inductor current of the boost converter is controlled by Average current mode (ACM) control and Variable hysteresis current control (HCC) methods and their performance is gauged in terms of total harmonic distortion (THD) and power factor improvement. The control strategies are developed and implemented in an FPGA-based rapid prototyping tool and an induction heating system experimentally validates their performance. The results obtained show the superiority of the ACM (THD 2.4%,4.3%) over HCC (THD 3.02%,6.3%) in simulation and experimentally both.