Primary-Side Dual-Loop Hysteresis Control for Fast Dynamic Response and Low Power Ripples in Inductive Power Transfer Systems

This paper presents a primary-side dual-loop hysteresis control method for series-series (SS) compensated inductive power transfer (IPT) systems. One of the two parallel hysteresis loops is designed to achieve fast transient response while the other ensures accurate steady-state power control and suppression of power oscillations in battery charging applications with constant voltage load (CVL) characteristics. Since the transferred power is accurately regulated by introducing individually skipped voltage pulses, zero voltage switching can be achieved across the entire operating range. The method also prevents the skipped pulses from exciting the poorly damped oscillation mode that can appear in IPT systems with CVLs. The closed-loop control is exclusively implemented on the primary side, eliminating the need for high-speed communication while allowing for steady-state correction through a low-bandwidth communication link. In addition to fast dynamic response, the proposed implementation enables high efficiency in a wide range of power and coupling while providing accurate power reference tracking. The proposed method is validated by simulations and results from a small-scale laboratory prototype, confirming its effectiveness and practicality.