Current Balancing for Avionics Power Systems
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Solution Overview
Problem
In avionics applications, multiple 28 VDC power sources with slight voltage differences lead to current imbalances, increasing the demand for maximum current capabilities and wiring, as conventional systems fail to ensure equal current distribution among redundant voltage inputs.
Innovation Solution
A system comprising current balancers with series pass elements and controllers that throttle these elements to balance output current, utilizing current sensors and amplifiers for feedback and control, ensuring balanced current distribution across multiple voltage sources.
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 with most current drawn from the higher voltage source
Solution Approach 1:
The patent implements feedback control by monitoring the voltage levels of multiple power sources and adjusting the series pass elements accordingly. The controller continuously measures voltage differences and modulates the pass elements to equalize current distribution, creating a closed-loop system that maintains balanced operation despite voltage variations among redundant sources.
Solution Approach 2:
The patent employs dynamic adjustment of series pass elements (such as MOSFETs or transistors) that can vary their resistance in real-time based on voltage conditions. This dynamic behavior allows the system to adapt to changing voltage levels across redundant sources, transforming static power distribution into a dynamically balanced state that equalizes current flow.
2Device complexity
If voltage differences between multiple power sources are not regulated, then system simplicity is maintained, but current imbalance increases requiring higher maximum current capabilities
Solution Approach 1:
The patent introduces series pass elements as intermediary components between the multiple power sources and the load. These pass elements act as mediators that control current flow from each source, preventing direct unbalanced connection. By placing these controllable elements in series with each power source, the system manages current distribution without requiring complete redesign of the power architecture.
3Reliability
If current is drawn solely from a single voltage input, then the OR-ing configuration functions correctly, but the maximum current capabilities of voltage supplies and wiring must be increased
Solution Approach 1:
The patent changes the operating parameters of the power distribution system by actively regulating the effective resistance of series pass elements. This parameter adjustment allows the system to distribute current across multiple sources rather than allowing single-source dominance, thereby reducing the peak current requirements for supplies and wiring while maintaining the OR-ing redundancy function.
Data Source
AI summary
A system comprises a first current balancer and a second current balancer. Each of the first and second current balancers includes a first input line for a first voltage source connected to a first output, a second input line for a second voltage source connected to a second output and is in parallel with the first input line, a first series pass element connected in series with the first input line, and a second series pass element connected in series with the second input line. The system further includes a controller 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.