Parallel DC-DC Converter Current Sharing Control
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Solution Overview
Problem
Existing power supply systems with multiple DC-DC converters connected in parallel face reliability issues due to uneven activation and potential voltage reduction, particularly when current demand is high, and require additional signal lines for current sharing, increasing system cost and size.
Innovation Solution
A power supply system with a voltage controller, current limiter, and specified value increasing unit that controls output voltages and currents of DC-DC converters, allowing for dynamic adjustment of current limits and voltage management to enhance reliability and current capacity, while minimizing the need for additional signal lines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If multiple DC-DC converters are connected in parallel to increase maximum current supply, then the current capacity is improved, but reliability decreases due to uneven activation frequency among converters
Solution Approach 1:
The patent implements dynamic adjustment of current limits for each DC-DC converter based on real-time operating conditions. The control unit monitors output currents and dynamically modifies the current limit values, allowing converters to operate at optimized current levels that balance reliability and current capacity. This dynamic control prevents any single converter from being overutilized while maintaining overall system power output.
Solution Approach 2:
The system changes the parameter of current limit values for each converter based on operating conditions. By adjusting these parameters dynamically, the system ensures that converters with higher activation frequencies operate at lower current limits, while those with lower frequencies can operate at higher limits, thereby balancing reliability across all converters while maintaining total current capacity.
2Reliability
If current sharing control is implemented by reducing output voltage when current exceeds reference, then reliability is improved, but voltage stability deteriorates under high current demand
Solution Approach 1:
Instead of uniformly reducing output voltage when current exceeds reference, the patent selectively adjusts the current limit parameters of individual converters based on their specific operating conditions and activation frequencies. This targeted parameter adjustment maintains voltage stability for the overall system while still implementing current sharing to improve reliability.
Solution Approach 2:
The patent segments the current control into individual converter-specific current limits rather than applying a unified voltage reduction approach. Each converter has its own adjustable current limit parameter that can be independently optimized, allowing the system to maintain voltage stability while achieving current sharing across multiple converters.
3Measurement precision
If signal lines are added for current sharing control, then current distribution accuracy is improved, but device complexity increases
Solution Approach 1:
The control unit performs multiple functions: it monitors output currents from all converters, determines activation frequencies, dynamically adjusts current limits, and maintains voltage regulation. By consolidating these functions into a single control unit, the patent eliminates the need for separate dedicated signal lines for current sharing control, reducing device complexity while maintaining current distribution accuracy.
Solution Approach 2:
The patent merges the current sharing control function with the existing voltage control functions in a unified control unit. This integration allows the system to achieve accurate current distribution without adding separate signal line infrastructure, as the control unit leverages existing monitoring capabilities and combines multiple control objectives into a single coordinated system.
Data Source
AI summary
A power supply system includes a plurality of DC-DC converters and at least one operating unit. The DC-DC converters are connected in parallel to one another. The at least one operating unit operates the DC-DC converters such that power is supplied through the DC-DC converters to a predetermined power-supplied object. The at least one operating unit includes a voltage controller, a current limiter, and an increasing unit. The voltage controller operates the DC-DC converters such that output voltages thereof are controlled to be respective target voltage. The current limiter limits output currents of the DC-DC converters so that they are limited with respect to a respective specified value. The increasing unit increases a specified value for at least one DC-DC converter of the DC-DC converters, when all of the plurality of DC-DC converters are activated and output current of at least one other DC-DC converter of the DC-DC converters reaches a specified value for the at least one other DC-DC converter.