New Driving Method of the Magnetron Power Supply for a Sulfur Plasma Lamp

This paper presents a new driving method for a sulfur plasma lamp in low-power applications. The newly developed magnetron power supply (MPS) is a series-resonance type with a full-bridge topology controlled by the phase shift to track the beam current of the magnetron. To drive the sulfur plasma lamp optimally, the MPS should: 1) provide peak power above a discharge condition to excite the sulfur plasma lamp, and 2) allow average power control of the light dimmer while satisfying condition 1. The newly developed driving method uses the burst mode, which enables both peak and average power controls to satisfy these conditions. Furthermore, a magnetizing current offset balancer is developed; it guarantees zero-voltage switching of all field-effect transistors, although the MPS operates in the burst mode. Thus, the proposed method provides easy lighting and relighting under optimized conditions with high efficiency. The power of the MPS delivered by the proposed method reached 1.6 kW with variable average power of 200 similar to 400 W by adjusting burst-on time proportionally. Experimental results proved the feasibility of the proposed driving method.