DC-DC Converter Leg Switching for Balanced Current and Durability
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Solution Overview
Problem
Existing DC-DC converters in fuel cell electric vehicles face inefficiencies and reduced durability due to unoptimized leg selection and unbalanced operation times in high-voltage power management systems.
Innovation Solution
A method and system for controlling DC-DC converters by selecting and switching a specific number of legs based on output current targets and accumulated operation times, using efficiency maps to optimize leg usage and balance operation times, thereby improving efficiency and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If all legs in the DC-DC converter are switched continuously to meet output current demands, then the output current target value can be achieved, but the accumulated operation time for each leg becomes unbalanced leading to reduced durability
Solution Approach 1:
The control method dynamically adjusts the number of active legs based on the output current target value. When the output current is high, more legs are activated to share the load; when the output current is low, fewer legs are activated to reduce stress on individual components. This dynamic adaptation allows the system to meet power demands while balancing the accumulated operation time of each leg, thereby improving durability.
Solution Approach 2:
The system changes the operational parameters (number of active legs) based on the output current target value. By reading the efficiency map and determining the appropriate number of legs to switch based on the output current target value, the system optimizes the balance between power delivery and component stress, preventing any single leg from accumulating excessive operation time.
2Productivity
If the number of switched legs is not optimized according to output current, then the DC-DC converter can operate continuously, but the efficiency is reduced due to operation in low-efficiency ranges
Solution Approach 1:
The system dynamically determines the number of legs to switch by reading the efficiency map and comparing it with the output current target value. This allows the DC-DC converter to operate in high-efficiency ranges across different load conditions while maintaining continuous operation capability. The efficiency map guides the selection of optimal leg configurations for various output current levels.
3Device complexity
If the accumulated operation time for each leg is not balanced, then switching operations can be simplified, but the durability performance of the DC-DC converter deteriorates
Solution Approach 1:
The control method incorporates feedback by monitoring the accumulated operation time of each leg and using this information to determine which legs should be switched next. The converter controller selects legs to be switched based on accumulated operation time for each leg, ensuring that legs with lower accumulated operation time are prioritized for switching. This feedback mechanism balances the wear across all legs, improving durability without significantly increasing control complexity.
Data Source
AI summary
A method for controlling a vehicle includes determining the number of driving legs according to an output current target value of a DC-DC converter; selecting one or more legs to be switched as many as the number of the driving legs from among a plurality of legs included in the DC-DC converter based on accumulated operation time for each of the plurality of legs; and controlling an output current value of the DC-DC converter to follow the output current target value by switching the selected one or more legs.