The anti-drone system refers to a system for shooting down target drones and consists of a high-voltage pulsed-power modulator, a magnetron, and an antenna. This study is about the design of a power supply for driving an S-Band magnetron that can be applied to an anti-drone system. Two power supplies are essential to drive the magnetron. A filament power supply for emitting hot electrons from the filament located at the cathode of the magnetron and a negative pulsed-power supply for accelerating the hot electrons emitted from the filament are required [1].
The designed pulsed-power modulator is a Solid-state Marx Generator type using IGBT. It has a 5-stage structure and consists of a charging part and a discharging part. The circuit that charges 60 capacitors in parallel is called the charging part, and the circuit that simultaneously turns on and off 60 IGBTs connected in series with the charged capacitors to output pulses is called the discharging part. When designing the charging part, an improved type of LCC resonant converter was designed to operate over a wide load range [2]. As a result, the crest factor and rms value of the resonance current were reduced to reduce conduction loss. In addition, because zero-voltage switching is possible, switch conduction loss is reduced. The discharging part has a total of 60 IGBTs stacked in series, and a special gate driving design that can transmit gate signals simultaneously to improve switch synchronization was applied. The inverter input voltage for switch driving was designed to be sufficiently high at 530 Vrms to increase the charging speed of each switch gate driving circuit input capacitor through a high didt. The secondary side of the inverter transformer for driving the switch is called the gate loop. 10 parallel gate loops are connected to the left and right sides of the 5-stage discharging part, respectively, and one gate loop is responsible for the switching operation of 6 IGBTs.
The filament power supply was designed with a simple full-bridge converter. The specifications required for a filament power supply to drive a magnetron are not as high as 10 V, 10 A, but since the potential of the filament is -52 kV, a high-voltage insulation design is required between the primary and secondary sides of the filament power supply transformer. Therefore, a power supply capable of tens of kV level insulation was designed through a double-insulated transformer design, and the current information flowing on the output side could be obtained indirectly by sensing the current on the primary side of the transformer. Depending on the impedance characteristics, the filament operates in most light load areas except when it is in a cold state before filament heating. Therefore, the Phase-Shifted PWM technique was selected considering efficiency and application of indirect sensing and operates at a fixed switching frequency of 50 kHz. The design of the two power supplies mentioned above was verified through realistic modeling using PSpice simulation, and the insulation performance of the designed filament power supply was confirmed through a connection test with the pulsed-power modulator at -52 kV and 120 A output. Afterwards, planning to verify a stable RF power output test through an actual S-Band magnetron linkage test.

[1] Su-Mi Park, Seung-Ho Song, Hyun-Bin Jo, Woo-Cheol Jeong, Sung-Roc Jang, and Hong-Je Ryoo. "Solid-State Pulsed Power Modulator for 9.3 GHz 1.7 MW X-Band Magnetron", Trans. On Industrial Electronics, VOL. 68 , NO. 2 , pg. 1148-1154 , Feb. 2021
[2] Sung-Roc Jang, Chan-Hun Yu, and Hong-Je Ryoo. "Trapezoidal Approximation of LCC Resonant Converter and Design of Multi-Stage Capacitor Charger for Solid-State Marx Modulator", Trans. On Power Electronics, VOL. 33 , NO. 5 , pg. 3816-3825 , May.2018

Solid-state pulsed-power modulator,magnetron,pulsed power