Performance Evaluation of Variable Pulse Density Modulation Algorithm in SWISS Rectifier for Induction Heating

Induction heating (IH) converts electrical energy into heat at a high efficiency, allowing fast, and localized heating which is desirable in forging and hardening applications. With power quality standards getting stricter and stricter, the power supply used for induction heating system would need to improve input power factor and input current total harmonics distortion. There have been many topologies and modulation methods proposed to solve this problem. Single-stage and power factor correction (PFC) front-end topologies are attractive due to their low cost, and high performance. Supporting the PFC front-end solution, this paper proposes the use of an active SWISS rectifier and a novel variable pulse density modulation for three-phase input currents shaping, as the first stage of a two-stage IH system, achieving high input power factor, wide power control range, and good efficiency. Simulation and experimental results confirmed the feasibility of the proposed topology and modulation algorithm.