High Power Density 10 kW Power Processing Unit for High Power Hall Thrusters

Busek Co. Inc. proposes to develop and package a cutting-edge high power density 10kW Power Processing Unit (PPU) using GaN Devices for High Power Hall effect thrusters (HETs). The PPU will feature high bandwidth high voltage side current sensor to provide thruster breathing mode data for Thruster operation optimization, an integrated input EMI filter to comply with MIL-STD-461, and modularity to serve a range of multi-kW class thrusters. The primary application is to drive the BHT-7000 HET being developed under SMC contract # FA8808-20-C-0041. The PPU development will enable application of the BHT-7000 for DoD, and the BHT-1500 and the BHT-6000 on commercial GEOsats. The BHT-6000 is being qualified by Busek for the NASA Gateway mission. The proposed effort will leverage the existing GaN based discharge breadboards featuring real time controllable thruster voltage, ~ 95% efficiency, and specific mass of ~1.8 kW/kg which is twice the performance of known SOA systems. The proposed 10 kW PPU will include state of the art devices, additional parallel DPS modules for full power, integrated bandwidth high voltage side current sensor, integrated controller, chassis based on thermal analysis, and shock and vibe consideration, and EMI filter integration. Busek has expertise in designing converters for space and will identify Radiation Compliant parts for the PPU. The PPU will be build using non-rad hard EEE parts that will be replaced by rad-hard parts (100kRads and 83MeV*cm^2/mg) and qualified for flight in future programs. This strategy is a cost driven necessity as the cost of rad hard parts exceeds the entire Phase 2 budget. The rest of the PPU including magnet power supply, cathode heater, keeper, igniter, and propellent flow control unit. In Phase 1, Busek will contact the customer and the major primes to approve the specifications to ensure maximum applicability. Busek will conduct technical feasibility analysis for the proposed PPU incorporating the specifications. In parallel, the design will be update incorporating newly available SOTA devices. Phase 2 will start by developing the 10 kW PPU on the basis of the existing discharge modules and rest of the converters in PPU. The high bandwidth current sensor will be re-designed to operate with 10 kW power level. The data from the high bandwidth current sensor will be used to automatically optimize the thruster operation. An EMI filter will be added so that the PPU compiles with MIL-STD-461. Preliminary structural and thermal modeling of the converters will be completed. The Phase 2 will culminate with PPU/HET coupling tests to demonstrate and validate the integrated system and PPU stability in transient events. Busek has established communications with the customer and Primes and obtained valuable inputs from the appropriate SMC/ZAE office. Planned USSF architectures and strategies all demand dramatically increased resilience which often means rapid maneuverability to escape potential threats.