Shunt active power filter implementation for induction heating applications

Abstract

PurposeThis paper aims to present the prototype of a 140 kVA shunt active power filter (APF) for current harmonics and fundamental reactive power compensation of a 200 kW induction heating system.Design/methodology/approachDesign issues of the power components, of the switching ripple filter and of the digital control are addressed and discussed. The APF control algorithm has been implemented on the 16‐bit, fixed‐point, TMS320LF2407 A DSP controller. The current control is based on proportional‐sinusoidal signal integrators with good performance in current harmonic elimination and power factor compensation.FindingsThe experimental tests, performed in real industrial environment for a 200 kW induction heating plant, show that the performance goals are fulfilled.Practical implicationsThe sinusoidal signal integrators (for consistency with the other plural forms of acronyms) of the current controller are implemented in the rotating reference frame aligned with the voltage vector at the point of common connection. This allows the compensation of two harmonics with a single SSI, thus halving the computational effort of the DSP.Originality/valueIn industrial induction heating, the need for harmonic and reactive power compensation lasts a few seconds per minute, making passive solutions not suitable. The presented APF is a valid solution for this application, where only a few tailored implementations are available on the market.