Parallel DC Power Supply Droop Control for Passive Load Sharing
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Solution Overview
Problem
In parallel DC power supplies for aircraft, load sharing is not optimal as the power supply with higher voltage output handles the entire load current, leading to potential overload and reduced lifespan, due to differences in output voltages caused by component tolerances and other factors.
Innovation Solution
A passive power sharing system where each DC power supply reduces its voltage output based on its own load current, independent of the other supply's current and the total system load, using current sensing devices and generator controllers to implement droop control, allowing for independent operation and reduced system communication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If parallel DC power supplies operate with fixed voltage output, then voltage stability is maintained, but load sharing becomes unbalanced causing one supply to handle entire load current
Solution Approach 1:
The patent changes the voltage parameter dynamically by introducing a droop characteristic where voltage output is reduced proportionally to the load current. Each power supply's voltage is adjusted based on its own current output, creating a self-balancing mechanism that distributes load evenly across parallel supplies while maintaining operational stability.
2Device complexity
If active rectification with power flow controllers is used, then power supply simplification is achieved, but complex control systems are required for load sharing
Solution Approach 1:
The patent implements self-service through autonomous droop control where each power supply independently adjusts its own voltage based on its load current without requiring communication or coordination with other supplies. This self-regulating mechanism simplifies the overall control system while achieving balanced load sharing.
3Reliability
If voltage droop control is implemented, then load sharing is improved, but voltage output is reduced
Solution Approach 1:
The patent applies dynamics by making the voltage output adjustable and responsive to load conditions rather than fixed. The droop characteristic creates a dynamic relationship where voltage automatically adapts to current levels, enabling balanced load distribution. The system maintains adequate voltage through proper design of the droop slope to ensure sufficient headroom for voltage regulation.
Data Source
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AI summary
System and methods for passive power sharing of parallel sources are provided. Aspects include a first DC power supply including a first generator and a rectifier circuit, a second DC power supply including a second generator and a second rectifier, wherein a first output of the first DC power supply and a second output of the second DC power supply are commonly coupled at a common bus point, a first current sensing device (212a) coupled between the first output of the first DC power supply and the common bus point, a first generator controller (202a) configured to receive a first current signal from the first current sensing device (212a), analyze the first current signal to determine a first voltage droop value based on the first current signal, and operate the first DC power supply to reduce a first voltage output of the first DC power supply by the first voltage droop value.