This paper presents the design and implementation of a high-voltage direct current (HVDC) power supply rated for 10 kV, 2 A (20 kW), developed to drive a 10 kW, 2.45 GHz industrial magnetron requiring approximately 8.8 kV, 1.6–1.8 A (16 kW input) under nominal operation. Accordingly, the HVDC supply was rated at 20 kW to allow margin for surges, efficiency variation, and future scaling. The converter core employs a full-bridge inductor-inductor-capacitor (LLC) resonant topology operating at a nominal switching frequency of 22 kHz, chosen for its high power density, inherent soft switching, and effective use of transformer leakage inductance in the resonant tank. A two-step soft-start sequence is implemented: the output first stabilizes at 6.8 kV in standby before smoothly rising to 8.8 kV for full-power operation, with a transition time below 200 ms and no overshoot. Closed-loop regulation is achieved through digital proportional–integral–derivative (PID) control on a Texas Instruments TMS320F280025C using pulses-frequency modulation (PFM). The prototype demonstrates stable voltage regulation with low output ripple (1%) while maintaining zero-voltage and zero-current switching (ZVS/ZCS) across the operating range. All high-voltage magnetic components, including the resonant inductor and custom 20 kVA transformer, were designed and built in-house to meet insulation and power-density requirements. Experimental validation confirms reliable startup, arc-free operation, and efficient power conversion under variable load conditions. In summary, the proposed digitally controlled LLC converter delivers a regulated 10 kV/2 A direct current (DC) output with controlled soft start, offering a compact, low-cost, and robust solution for industrial magnetron and plasma heating applications.
Ninet M. Ahmed (Sat,) studied this question.