Conditional Pulse Density Modulation for Inductive Power Transfer Systems

This letter proposes a conditional pulse density modulation (PDM) method for inductive power transfer (IPT) systems, which can automatically adapt the generated output patterns to effectively suppress current/power ripples. The proposed conditional PDM introduces a sending current limitation as an additional condition to skip pulses, which modifies the output patterns generated by conventional delta-sigma-based PDM. Thus, the PDM pulse pattern is continuously adapted to attenuate any excited current/power oscillations. The presented modulator is simple to implement and well-suited for IPT systems with poorly damped constant voltage load characteristics. Simulations and experiments demonstrate the effectiveness of the proposed modulation method.