Dual 28 VDC Input Current Balancing With Series Pass Control
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Solution Overview
Problem
In avionics systems with multiple redundant 28 VDC voltage inputs, slight voltage differences lead to unequal current distribution, increasing the demand for maximum current capabilities and harness wiring, as conventional methods fail to ensure equal current distribution.
Innovation Solution
A system with current sensors, difference amplifiers, and proportional integral controllers is used to balance output current between two input lines by throttling series pass elements, ensuring equal current distribution and avoiding breaker tripping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple redundant voltage sources are used to power avionics applications, then system reliability is improved, but current distribution becomes unbalanced and maximum current requirements increase
Solution Approach 1:
The patent implements a feedback control system using current sensors to monitor the current drawn from each voltage source. The controller receives feedback signals from these sensors and dynamically adjusts the series pass elements to balance the current distribution, ensuring that each source contributes equally to the total power demand.
Solution Approach 2:
The system employs dynamic adjustment of the series pass elements (such as MOSFETs or transistors) controlled by a microcontroller or analog circuitry. This allows real-time modulation of the current path resistance to equalize current flow from multiple voltage sources, adapting to changing load conditions and voltage variations.
2Reliability
If multiple redundant voltage sources are used, then system reliability is improved, but wiring and power supply requirements become more complex
Solution Approach 1:
The patent merges multiple voltage source paths into a unified current balancing architecture. By combining the control of series pass elements under a single controller that monitors all sources, the system reduces the complexity of wiring and power supply design while maintaining reliability benefits of redundancy.
3Adaptability or versatility
If voltage sources are not regulated to the exact same voltage level, then system flexibility is improved, but current imbalance occurs with majority current drawn from the higher voltage source
Solution Approach 1:
The system changes the electrical parameters (current flow, resistance) of each voltage source path dynamically. By adjusting the resistance of series pass elements based on real-time voltage and current measurements, the controller equalizes current distribution even when source voltages differ, maintaining flexibility in voltage source selection.
Data Source
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AI summary
A system includes a first input line (102) for a first voltage source (104), wherein the first input line is connected to a first output (106). A second input line (108) is included for a second voltage source (110), wherein the second input line is connected to a second output (112) and is in parallel with the first input line. A first series pass element (114) is connected in series with the first input line, and a second series pass element (116) is connected in series with the second input line. A controller (118) is operatively connected to the first series pass element and to the second series pass element to throttle at least one of the first series pass element and the second series pass element to balance output current in the first and second outputs.