High-Order Compensated Wireless Power Transfer for Dimmable Metal Halide Lamps

A high-order compensated wireless power transfer (WPT) system is proposed and implemented for dimmable metal halide (MH) lamps without using any ignitor or ballast. Possessing high ignition voltage and constant current output, the LCC-LC compensated WPT is identified to be more competent for MH lamps as compared with the four basic compensation networks as well as the double-sided LCC compensation networks. Meanwhile, dimming control and power stabilization are achieved by the phase-shift modulation, and the multilayer multitype coil is newly proposed to enhance the tolerance of varying coupling coefficients. For exemplification, a wireless dimmable MH lamp operating at 400 kHz has been designed and prototyped. Particularly, the system can tolerate coil deviation up to 20 cm and dim the lamp down to 30% of standard illuminance with the merit of acoustic resonance free. Both theoretical and experimental results are given to validate the feasibility of the proposed system.