Parallel DC Power Supply Control for Balanced Load Sharing
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Solution Overview
Problem
In more electric aircraft, parallel DC power supplies do not automatically share loads equally, leading to overloading and potential failure of one power supply due to slight differences in output voltages caused by component tolerances and other factors.
Innovation Solution
A system with first and second DC power supplies, each with a generator and rectifier, coupled at a common bus point, using current sensing devices to calculate common mode current and determine voltage foldback values, allowing generators to reduce their output voltage based on shared current signals, ensuring balanced load sharing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If parallel DC power supplies are connected without voltage balancing control, then the system provides redundant power capacity, but one power supply becomes overloaded and may fail due to unequal load sharing
Solution Approach 1:
The patent implements a feedback control mechanism where each power supply's controller continuously monitors the voltage output of other parallel power supplies and adjusts its own voltage accordingly. This closed-loop feedback ensures automatic load balancing without requiring complex communication protocols, resolving the contradiction by maintaining equal load distribution while preserving system redundancy.
Solution Approach 2:
Each power supply unit independently adjusts its own voltage output based on sensed system conditions without requiring external control intervention. The self-service mechanism allows each unit to autonomously participate in load sharing, eliminating the need for centralized control while ensuring balanced operation and improving overall system reliability.
2Productivity
If voltage foldback control is implemented using common mode current analysis, then load sharing balance is improved, but the device complexity increases due to additional sensing and control circuitry
Solution Approach 1:
The controller performs multiple functions using the same sensing infrastructure: it monitors common mode current for load balancing, detects fault conditions, and regulates voltage output. This multi-functionality reduces the need for separate dedicated circuits for each control objective, thereby improving load sharing balance while minimizing the increase in device complexity.
Solution Approach 2:
The patent combines the voltage sensing, current monitoring, and control decision-making functions into a single integrated controller per power supply unit. By merging these functions, the system achieves sophisticated load sharing through common mode current analysis without requiring separate independent circuits for each function, thus balancing improved productivity with controlled complexity.
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 approach ensures balanced load sharing between parallel DC power supplies, preventing overloading and extending the lifespan of power supplies by using common mode current analysis for voltage foldback, thereby enhancing the reliability and efficiency of power distribution in aircraft systems.
Implementation Method 1
The first current sensing device can be a hall effect sensor
Data Source
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AI summary
A power supply system includes first and second generators that are measured by first and second current sensors. The system also includes a first generator controller configured to: receive a first current signal from the first current sensing device and a second current signal from the second current sensing device; analyze the first current signal and the second current signal to determine a first voltage foldback value based on a first common mode current calculated from the first current signal and the second 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 foldback value.