Spacecraft Latch Current Limiter Using Resistive Overcurrent Mode
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Solution Overview
Problem
Existing latch current limiter circuits for aerospace equipment fail to effectively limit overcurrent conditions and provide adequate protection for electronic components, potentially leading to damage or safety issues such as fire.
Innovation Solution
A latch current limiter circuit for spacecraft power systems, incorporating a current sensing circuit, a transistor switch circuit, and a transistor switch control circuit, which includes a transformer, an LC resonant circuit, a rectifier filtering circuit, a switching circuit, and a relaxation oscillator circuit. This circuit limits excessive current flow by shifting the operating frequency away from the resonance point, causing the transistor switch to operate in a resistive mode and providing a predetermined time for temporarily faulted loads to restart.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a latch current limiter circuit uses a current sensing component to monitor current and cut off the circuit when current exceeds a threshold, then the circuit protection function is improved, but the circuit complexity increases due to additional components and control mechanisms
Solution Approach 1:
The latch current limiter circuit automatically monitors current through the sensing component and triggers cutoff when threshold is exceeded, without requiring external control. The circuit self-activates and self-manages the protection function, reducing the need for additional control components and simplifying the overall system architecture
Solution Approach 2:
The circuit pre-establishes a current threshold and sensing mechanism that automatically triggers protection before damage occurs. By having the cutoff mechanism ready and automatically activated upon threshold violation, the system prevents harmful conditions without requiring complex real-time decision-making circuits
2Speed
If the latch current limiter circuit quickly cuts off the circuit to prevent damage, then the protection speed is improved, but the load loses power supply continuity and cannot recover from temporary faults
Solution Approach 1:
The circuit implements periodic monitoring of current conditions and allows for reset cycles after fault clearance. The cutoff is not permanent but operates in cycles, enabling the load to recover after temporary faults while maintaining rapid protection response. This periodic operation balances quick protection with power supply continuity
Solution Approach 2:
The circuit provides a predetermined recovery period after cutoff before allowing full power restoration. This preliminary anti-action prevents immediate re-triggering from transient faults while ensuring rapid protection when genuine overcurrent conditions persist, thus maintaining both protection speed and power continuity
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
The proposed solution effectively limits overcurrent conditions, protecting aerospace equipment from damage and providing a controlled restart opportunity for temporarily faulted loads, thereby enhancing the reliability and safety of spacecraft power systems.
Implementation Method 1
The current sensing circuit is coupled between the input terminal and the output terminal for outputting a current sense voltage according to the current flowing from the input terminal to the output terminal
Implementation Method 2
The LC resonant circuit is coupled to the primary side coil of the transformer
Implementation Method 3
The relaxation oscillator circuit receives the current sense voltage, and outputs a clock signal to the input terminal of the switching circuit, for controlling the switching circuit
Implementation Method 4
causing the transistor switch to operate in a resistive mode and providing a predetermined time for temporarily faulted loads to restart
Data Source
AI summary
The embodiment of the present invention relates to a latch current limiter (LCL) circuit for spacecraft and a spacecraft power system using the same. The LCL circuit are coupled between a power supply terminal and a power receiving terminal, wherein a semiconductor switch circuit is configured between the power supply terminal and the power receiving terminal. The semiconductor switch circuit includes a conduction mode, a cut-off mode and a resistance mode. Moreover, an LLC DC-to-DC converter is adopted for controlling the semiconductor switch circuit. When the current is greater than the over-current value, the LLC DC-to-DC converter changes its operational frequency to change the output voltage such that the semiconductor switch circuit is controlled to enter the resistance mode. After a preset period, when the current does not return the regular value, the LLC DC-to-DC converter controls the semiconductor switch circuit to enter the cut-off mode such that the power which supplies to the load is turned off.