Adaptive Self-Tuned Controller IC for Resonant-Based Wireless Power Transfer Transmitters

This article introduces an adaptive self-tuned controller IC for resonant wireless power transfer (RWPT) transmitters. The controller IC comprises an on-the-fly very-high-frequency tracking hardware with high resolution and an independent high-resolution digital pulsewidth modulator (PWM)-based (HR-DPWM) current programmed control. These facilitate precise frequency generation as well as adaptive tuning of the reactive components in the matching network, which translate into tight current/power regulation capabilities while retaining optimized power transfer conditions on the transmitting side. The controller IC enables to effectively disengage the power-delivery capabilities from the variations of the resonators, electrical circuits, and wireless medium. The controller core is based on a fully synthesizable digital architecture that has been realized through HDL tools, and several key building blocks have been developed and described in detail: a delay-line-based phase detector, high-resolution digital frequency synthesizer, and HR-DPWM. To fully exploit the benefits of digital electronics, reduce power consumption, and save area, the digital core of the controller has been designed completely through asynchronous architecture, eliminating the need of high-speed clock and its related hardware. The mixed-signal controller IC has been designed, implemented, and fabricated in 0.18-μm 5-V CMOS process, resulting in effective silicon area of 0.6 mm2. To demonstrate the mixed-signal controller IC in closed-loop operation of a wireless power system, an experimental 20-W resonant capacitive-based WTP system has been designed and validated. The effectiveness of the controller is well demonstrated and evaluated at the MHz range up to 200 mm misalignment, meeting the strict requirements of resonant-based WPT systems.