Current Sharing Bus Control for Parallel Power Supplies Under Light Load
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Solution Overview
Problem
Existing power supply systems with multiple modules in parallel face current imbalance due to inconsistent circuit parameters, leading to inefficiencies in current sharing, particularly under light-load conditions where analog operational amplifiers exhibit large errors and fail to provide accurate and fast dynamic response.
Innovation Solution
A power supply system with a current sharing bus and controllers that adjust output voltage bi-directionally to achieve current sharing, using digital software or firmware to set power supply ratios adaptively, allowing each unit to dynamically adjust output currents based on received signal values, thereby ensuring accurate and fast response.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the maximum current sharing method through a current sharing bus is used, then current sharing control is achieved, but the output voltage cannot be adjusted to decrease and accuracy deteriorates under light-load operation
Solution Approach 1:
The patent inverts the conventional unidirectional voltage adjustment approach by implementing bidirectional voltage adjustment capability. The output voltage can be both increased and decreased based on current sharing requirements, allowing the system to achieve accurate current sharing under both heavy-load and light-load conditions. This resolves the contradiction by enabling voltage to move in the opposite direction (decrease) when needed, rather than being constrained to only increase.
Solution Approach 2:
The patent implements dynamic voltage adjustment by allowing the output voltage to flexibly change in both directions based on real-time current sharing needs. The voltage adjustment is no longer static or unidirectional but dynamically adapts to load conditions, enabling the system to maintain high precision current sharing accuracy across varying operating conditions including light-load scenarios.
2Reliability
If analog operational amplifier is used for current sharing control, then current sharing is achieved, but large errors occur under light-load operation
Solution Approach 1:
The patent replaces the analog operational amplifier-based control system with a digital control system. This substitution eliminates the inherent limitations of analog components under light-load conditions, where analog amplifiers exhibit large errors. The digital controller provides precise control and calculation capabilities, maintaining high current sharing accuracy across the full range of load conditions without the errors associated with analog operation near the zero point.
3Device complexity
If unidirectional voltage adjustment is used, then simple control is achieved, but fast dynamic response to high current demands cannot be provided
Solution Approach 1:
The patent implements dynamic bidirectional voltage adjustment that enables fast response to changing current demands. By allowing voltage to adjust in both directions based on real-time requirements, the system can quickly respond to sudden increases or decreases in current demand without being constrained by unidirectional adjustment limitations. This dynamic capability provides fast transient response while maintaining manageable control complexity through systematic control strategies.
Data Source
AI summary
A power supply system with current sharing includes a current sharing bus, a plurality of power supply units, and a plurality of controllers. The power supply units are connected to each other through the current sharing bus. Each power supply unit provides a current sharing signal value to the current sharing bus, and provides an output current to a load. Each controller receives current sharing signal values provided from other power supply units and current signal values corresponding to the output currents. When determining that the current signal value is less than a reference current sharing signal value, the controller increases an output voltage of the power supply unit to increase the output current. Otherwise, the controller decreases the output voltage to decrease the output current so that so that the output currents of the power supply units are shared to supply power to the load.