This paper aims at searching for the application of a ring type passive low pass filter (LPF) to reduce the entry of undesired harmonics to the input source from the inverter side of a full-bridge inverter based induction heating systems. The low pass filter is placed in between the ac input voltage source and high frequency full-bridge inverter based domestic induction heater. The inverter circuit is realized with insulated gate bipolar junction transistors (IGBT) as main power electronic switches. Unwanted harmonics are produced in the system due to non-linear behavior of the load under the effect of the power semi-conductor switches, which make the source current waveform non-sinusoidal. In this paper, the induction heating system is subjected to asymmetrical voltage cancellation (AVC) control and fast Fourier transform (FFT) method is utilized for frequency domain analysis to realize influence of harmonics. The whole system is implemented in power simulator (PSIM) environment. It is found that the proposed filter can decrease the total harmonic distortion (THD) and increase the distortion factor (DF) of the input current. Moreover, it is also proved that the can also improve the input power factor.

Keywords: Asymmetrical-voltage-cancellation (AVC), Induction heating system, Insulated gate bipolar transistor (IGBT), Low pass filter (LPF), Power-simulator (PSIM), Total harmonic distortion (THD)