High Efficiency, Versatile Power Processing Units for Hall-Effect Plasma Thrusters

摘要

Space Systems Loral (SSL) has developed a high efficiency versatile 4.5KW Power Processing Unit (PPU) that is currently in production for use with Hall-effect plasma thrusters such as the SPT-140. The PPU architecture enables a variety of Electric Propulsion (EP) missions with optimized profile and its modularity is a suitable baseline for next generation multi-voltage modes units. The PPU uses three paralleled Zero Voltage Switching (ZVS) Anode trays to convert 100V spacecraft bus power to 300V thruster discharge voltage. Each converter processes 1.5KW at 96% peak efficiency for a PPU efficiency of 94% during steady-state SPT operation at rated power. The ZVS scheme does not employ any auxiliary reactive or semiconductor components. By PLL synchronizing the switch drive with the natural resonance of power stage parasitic capacitances and magnetizing inductance, ZVS is achieved in a simple and efficient manner. An advantage of this scheme is that the switching frequency decreases with the load rather than increasing, which reduces losses and dissipation during high power operation. This paper addresses the salient PPU-Thruster functions, presents EP subsystem performance data, and ends with an overview of future works.