Reduced-order model of a half-bridge series resonant inverter for power control in domestic induction heating applications

When modeling resonant inverters considering the harmonic balance method, the order of the obtained transfer functions is twice the state variables number. This is explained because two components are considered for each state variable. In order to obtain a simpler transfer function model of a halfbridge series resonant inverter, different techniques of model order reduction have been considered in this work. Thus, a reduced-order model has been obtained by residualization providing much simpler analytical expressions than the original model. The proposed model has been validated by simulation and experimentally. The validity range of the proposed model is extended up to a tenth of the switching frequency. Taking into account the great load variability of induction heating applications, the proposed reduced-order model will allow the design of advanced controllers such as Gain-Scheduling.