Wireless Power Supply for Driving UV Lamps based on Autonomous Push-pull Converter with Additional Bias Network

This paper aims to develop a wireless/contactless power supply to drive an ultraviolet (UV) lamp by designing an MHz autonomous push-pull inverter with an additional bias network. The phase-splitting inductors of the inverter are coupled with receiver coils to reduce the total size and weight of the power supply. A bias network is introduced to the primary resonant tank to hold the operating frequency of the push-pull inverter. The frequency bifurcation range is narrowed for obtaining a high voltage gain to ignite the UV lamp. Theoretical analyses were performed based on a simplified equivalent circuit model to identify the three bifurcation frequencies of the system. In-depth analyses were conducted to evaluate the effect of the bias network on both the frequency bifurcation range and the voltage gain of the system. An equation was derived to determine the optimal value of the secondary tuning capacitor for maximizing the system's voltage gain under bifurcated conditions. The proposed system and theoretical analysis are validated by simulation study first, then a prototype with a DC input voltage of 16 V and a nominal frequency of 1 MHz is built. It is demonstrated that the actual striking voltage can reach 290 V, which is sufficiently high to ignite the UV lamp for a successful transition to steady-state operation.