Parallel Power Supply Load Balancing via Voltage Droop
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Solution Overview
Problem
Power supply systems with multiple units connected in parallel face issues with uneven load distribution due to deviating internal resistances and voltage regulator settings, leading to reduced total nominal power availability and increased power losses.
Innovation Solution
Each controller is set with a first drop value for the output voltage when the first current limit is reached, allowing power units to operate without a higher-level controller or signal connection, minimizing losses and ensuring all units contribute equally until all reach the current limit, with a two-stage current distribution concept to manage overload and limit modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If power units are connected in parallel to increase total power output, then the available power is improved, but uneven load distribution occurs due to deviating internal resistances and voltage regulator settings
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the output voltage of individual power units based on their current output level. When a power unit's current exceeds a predetermined threshold, its output voltage is reduced, which in turn reduces its current contribution. This dynamic parameter adjustment ensures balanced load distribution across all parallel-connected power units, resolving the uneven load distribution problem caused by manufacturing tolerances in internal resistances and voltage regulator settings.
2Manufacturing precision
If output voltage is continuously lowered to equalize current distribution, then load balance is improved, but power loss increases due to high resistance values
Solution Approach 1:
The patent implements partial action by only adjusting the output voltage of power units that exceed the predetermined current threshold, rather than continuously lowering the voltage of all power units. This selective adjustment minimizes the overall voltage drop across the system, thereby reducing power losses while still achieving balanced current distribution among the parallel-connected power units.
3Device complexity
If separate controllers are used for each power unit, then system complexity is reduced, but load balancing becomes difficult without higher-level coordination
Solution Approach 1:
The patent applies self-service by enabling each power unit's controller to independently monitor its own current output and autonomously adjust its output voltage when the current exceeds the predetermined threshold. This decentralized control mechanism allows each power unit to self-regulate its load contribution without requiring complex higher-level coordination or communication between controllers, thus maintaining simple system architecture while achieving effective load balancing.
Data Source
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AI summary
The invention relates to a control method for a power supply system having at least two power parts (L1, L2, L1', L2'), having power outputs which are connected in parallel, wherein each power part (L1, L2, L1', L2') is actuated by means of a separate control (STR1, STR2) and wherein at least one first power limit (S1) is specified for each control (STR1, STR2), the control (STR1, STR2) actuating the allocated power part (L1, L2, L1', L2') up to said first power limit in a normal mode. According to the invention, a first drawdown value (UA, UA') of the output voltage (UOUT, UOUT1, UOUT2) is specified for each control (STR1, STR2) upon reaching the first power limit (S1), and the respective control (STR1, STR2) regulates the output voltage (UOUT, UOUT1, UOUT2) of the related power part (L1, L2, L1', L2') to the first drawdown value (UA, UA') upon reaching the first power limit (S1). Such a control method enables the parallel connecting of a plurality of power parts (L1, L2, L1', L2') without a super-ordinate control.