Parallel DC-DC Converter Load Balancing via Target Voltage Adjustment
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Solution Overview
Problem
In voltage supply systems for electric vehicles, DC-DC converters connected in parallel often have variations in output voltages, leading to unequal load distribution and premature deterioration of specific converters, as existing solutions like Patent Literature 1 cannot set desired load ratios for each converter and suffer from voltage changes during load current variations.
Innovation Solution
A power source system with a constant voltage mode and a voltage generation unit that can switch between constant voltage and constant current modes, allowing for setting desired load ratios and suppressing output voltage changes by adjusting current limit values and delayed start mechanisms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If multiple DC-DC converters are connected in parallel to increase current capacity, then the current supply capability is improved, but the load distribution becomes unequal due to output voltage variations, causing premature deterioration of specific converters
Solution Approach 1:
The patent applies parameter changes by setting different target output voltages for each DC-DC converter. Specifically, the converter with higher output voltage has its target voltage set lower, while the converter with lower output voltage has its target voltage set higher. This parameter adjustment equalizes the load distribution among parallel converters, preventing premature deterioration and improving overall system reliability while maintaining increased current capacity.
2Productivity
If DC-DC converters with different output voltages are operated in parallel, then current can be distributed among them, but the output voltage of the entire system becomes unstable and fluctuates
Solution Approach 1:
The patent implements feedback control by continuously monitoring the actual output voltage of each DC-DC converter and comparing it with its assigned target voltage. Based on this feedback, each converter adjusts its output to match its target voltage, ensuring that the combined output voltage remains stable despite the parallel connection of converters with different characteristics. This feedback mechanism enables both load distribution and voltage stability.
3Device complexity
If a single DC-DC converter is used, then the system structure is simple, but the current capacity is insufficient when the load requires great current
Solution Approach 1:
The patent applies segmentation by dividing the single converter function into multiple parallel DC-DC converters. Each converter handles a portion of the total current load, thereby increasing the overall current capacity of the system. The patent further segments the control parameters by assigning different target voltages to each converter based on their individual characteristics, enabling equal load distribution and preventing any single converter from becoming a bottleneck.
Data Source
AI summary
A voltage supply system and a power source that, in a voltage supply system in which a plurality of power sources (e.g., DC-DC converters) are connected in parallel, enable each power source to be set at a desired load ratio. The power source is used in a voltage supply system including a power source configured to output a voltage in a constant voltage mode on the basis of a first target voltage, and is connected in parallel to the constant voltage power source, the power source including a voltage generation unit configured to output a voltage switchably between a constant voltage mode based on a second target voltage greater than the first target voltage and a constant current mode based on a current limit value.