Electric Propulsion Power Circuit Relay Closure Detection
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Solution Overview
Problem
In electric propulsion systems for satellites and spacecraft, the thruster power supply faces challenges in confirming the closure of the start relay to prevent diode damage from excessive current flow, which can lead to power loss and potential damage if the relay does not close correctly after the thruster enters its arc state.
Innovation Solution
A power supply circuit with a unidirectional current valve and a current detector, including a switch and a controller, is used to detect current flow through the unidirectional current valve and confirm relay closure, triggering remedial measures such as shutting down the power supply if closure is not detected, thereby preventing diode damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the unidirectional current valve is used to protect the diode during the first period of time, then the diode is protected from excessive current flow, but the device complexity increases due to the additional current detector and switch components
Solution Approach 1:
The patent introduces a current detector as an intermediary component that monitors current flow through the unidirectional current valve. This mediator detects when the thruster enters arc state and triggers the switch to bypass the diode, preventing direct damage while maintaining system reliability without requiring complex control logic
Solution Approach 2:
The current detector provides feedback about the current flow status to the controller, which then actuates the switch to change the circuit configuration. This feedback mechanism enables automatic protection of the diode based on real-time current conditions, resolving the contradiction between simplicity and reliability
2Loss of energy
If the switch bypasses the unidirectional current valve during the second period of time, then power loss is reduced and efficiency is improved, but the risk of diode damage increases if the relay fails to close
Solution Approach 1:
The current detector is configured to detect current flow through the unidirectional current valve as a preliminary condition before the controller actuates the switch. This preliminary detection ensures that the bypass is only activated when the thruster has safely entered arc state, preventing premature bypass that could expose the diode to damaging currents
Solution Approach 2:
The feedback from the current detector provides real-time information about whether the diode can be safely bypassed. The controller uses this feedback to make an informed decision about switch actuation, balancing energy efficiency gains against diode protection requirements based on actual thruster operating conditions
3Reliability
If the current detector continuously monitors current flow to confirm relay closure, then the reliability of relay operation is improved, but the use of energy increases due to continuous monitoring
Solution Approach 1:
The current detector performs periodic monitoring of current flow through the unidirectional current valve at critical transition points (end of first period, beginning of second period) rather than continuous monitoring. This periodic checking approach confirms relay closure reliability while minimizing energy consumption by keeping the monitoring circuit dormant during stable operating phases
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 solution ensures the thruster power supply transitions safely to its low voltage, high current mode and minimizes diode damage by confirming relay closure, ensuring reliable operation and preventing power loss.
Implementation Method 1
The unidirectional current valve (e.g., a diode) is connected in series with the second power source
Implementation Method 2
The current detector determines whether the second period of time has commenced and whether the switch has closed
Implementation Method 3
The transformer converts a relatively low pulsed voltage applied to its primary winding into a relatively high pulsed output voltage
Implementation Method 4
The pulsed output voltage is then supplied to the electric discharge device so as to cause the reaction thruster to enter an arc state
Data Source
AI summary
A circuit (400, 700, 800) comprising: a first power source (402) supplying first current to a load (470) during a first Period of Time (“PoT”); a second power source (416) supplying a second current to the load during a second POT; a Unidirectional Current Valve (“UCV”) in series with the first power source; a current detector (420, 702, 802) in series with the UCV (422); and a switch (424) in parallel with a series combination of the current detector and UCV to bypass the UCV during the second PoT. The current detector determines whether the second period of time has commenced and whether the switch has closed.