Parallel DC Power Supply Voltage Feedback for Balanced Load Sharing
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Solution Overview
Problem
In parallel DC power supply systems for aircraft, unequal load sharing occurs due to slight differences in output voltages among identical power supplies, leading to overloading and potential failure of one power supply while the others remain underutilized.
Innovation Solution
A system that includes two DC power supplies with current sensing devices and generator controllers, where the controllers analyze common mode current signals from both power supplies to determine voltage foldback values, ensuring balanced load sharing by reducing the voltage output of each power supply proportionally.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If multiple identical DC power supplies are connected in parallel to provide electrical power to aircraft loads, then the total power capacity and reliability are improved, but unequal load sharing occurs due to slight voltage differences causing one power supply to overload while others remain underutilized
Solution Approach 1:
The system measures the common mode current (sum of currents from all parallel power supplies) and uses this feedback signal to dynamically adjust the voltage output of each power supply. The controller continuously monitors the total current demand and modifies each unit's voltage to maintain proportional current sharing, preventing any single unit from overloading while ensuring all units contribute appropriately to the total load.
Solution Approach 2:
The invention dynamically changes the voltage parameter of each power supply based on the measured common mode current. By adjusting the voltage foldback value proportionally for each unit according to its current output, the system maintains balanced load sharing. This parameter adjustment ensures that power supplies with slightly different characteristics still share the load equally under varying operating conditions.
2Reliability
If voltage foldback control is applied to prevent overloading, then the reliability and lifespan of power supplies are improved, but the voltage output is reduced which may affect power delivery capability
Solution Approach 1:
The voltage foldback control is dynamically adjusted based on real-time common mode current measurements rather than being a fixed reduction. The controller continuously adapts the voltage output of each power supply according to the actual load conditions and current sharing requirements. This dynamic approach ensures that voltage is reduced only when necessary to maintain balanced load sharing, maximizing power delivery capability while preventing overloading and ensuring reliable operation.
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 solution achieves balanced load sharing among parallel DC power supplies, preventing overloading and extending the lifespan of the power supplies by ensuring all units contribute equally to the system load.
Implementation Method 1
a first current sensing device coupled between the first output of the first DC power supply and the common bus point; a second current sensing device coupled between the second output of the second DC power supply and the common bus point
Data Source
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.