Scalable Hall-Effect Thruster Power Processing Units
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Solution Overview
Problem
Current power processing technologies for Hall-effect thrusters (HETs) face challenges in reducing circuit complexity, achieving efficient current sharing between parallel isolated discharge supply modules, and meeting high voltage ignition requirements, which affects the scalability and cost-effectiveness of HET propulsion systems, especially for small spacecraft.
Innovation Solution
Implementing a current estimation technique on each output of parallel isolated discharge supply modules to force proper current sharing and using a flyback power supply that performs dual functions of cathode plasma ignitor and sustainer, with a low part count open-loop push-pull converter for higher voltage DC ignition, reducing the need for separate high voltage ignitor supplies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate high voltage ignitor supplies are used for cathode plasma ignition, then ignition reliability is improved, but device complexity and part count increase
Solution Approach 1:
The patent combines the cathode ignitor and keeper functions into a single integrated power supply unit. The keeper circuit provides both the high voltage pulses needed for ignition and the sustained voltage for plasma maintenance, eliminating the need for separate ignitor and keeper power supplies. This merging reduces part count and circuit complexity while maintaining reliable ignition performance.
Solution Approach 2:
The keeper power supply is designed to perform multiple functions: it provides high voltage pulses for cathode ignition, sustains the plasma discharge, and regulates current during operation. This multi-functional design eliminates dedicated ignitor circuits and simplifies the overall power processing architecture.
2Power
If parallel isolated discharge supply modules are used to increase power capacity, then power output is improved, but current sharing between modules becomes difficult
Solution Approach 1:
The patent implements a feedback mechanism where the controller monitors the output current of each parallel module and adjusts the duty cycle of pulse-width modulation to equalize current distribution. This feedback control ensures that multiple parallel modules share the load proportionally, enabling scalable power output without complex current balancing circuitry.
Solution Approach 2:
The system uses dynamic pulse-width modulation to adjust the operating parameters of each parallel module in real-time based on load conditions. This dynamic control allows the modules to automatically balance their current output, facilitating easy scaling from single to multiple modules without requiring complex static current sharing circuits.
3Reliability
If multiple separate power supplies are used for different thruster functions, then functional reliability is improved, but ease of manufacture and cost worsen
Solution Approach 1:
The patent merges multiple power supply functions (discharge, heater, keeper, magnet) into integrated power processing units. Each module combines multiple functions that traditionally required separate power supplies, reducing the total number of components, simplifying manufacturing, and lowering costs while maintaining functional reliability through careful circuit design.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach results in a high efficiency, low part count, scalable architecture for HET propulsion systems, enhancing electrical efficiency, reducing circuit complexity, and lowering costs, while enabling compact and reliable power processing for a wide range of HET devices and missions beyond low Earth orbits.
Implementation Method 1
The Hall-effect thruster (HET) is the most successful in-space electric propulsion technology by quantity of units flown
Implementation Method 2
The E×B force greatly slows the mean axial velocity of electrons and results in an azimuthal electron current many times greater than the beam current
Implementation Method 3
a flyback power supply performing the dual functions of cathode plasma ignitor and sustainer
Data Source
AI summary
Scalable power processing units (PPUs) for Hall-effect thrusters (HETs) and terrestrial systems are disclosed. A technique for current estimation may be employed on each output of parallel isolated discharge supply modules (DSMs) to force proper current/load sharing between the DSMs. A flyback power supply may be used that performs the dual functions of a cathode keeper plasma ignitor and sustainer. The flyback power supply may be tuned for a high no-load direct current (DC) output voltage to achieve cathode keeper ignition rather than requiring a separate ignitor supply, which reduces circuit complexity. To address requirements for higher voltage DC ignition than are achievable with a flyback power supply alone, a supplemental DC ignitor may be placed in parallel with the flyback power supply of some embodiments. Such simplified PPU architectures may provide a high efficiency, low part count, scalable architecture suitable for more compact and lower cost system designs.