Multi-Converter EV Energy Storage for Thermal and SOC Balancing
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Solution Overview
Problem
Existing vehicle energy storage systems face challenges in balancing state-of-charge (SOC) and temperature variations across multiple DC-DC power converters, leading to potential catastrophic failures in low voltage systems, especially in electric vehicles.
Innovation Solution
Implementing multiple DC-DC power converters connected across individual columns or modules of the energy storage system, with a control algorithm that prioritizes converters based on temperature and SOC to balance power distribution and prevent failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple DC-DC power converters are used to supply power to low voltage loads, then power supply redundancy and reliability are improved, but temperature variations and SOC imbalances across converters worsen
Solution Approach 1:
The control algorithm dynamically adjusts the output voltage setpoint of each DC-DC converter based on its real-time temperature and SOC status. Converters operating at higher temperatures or with lower SOC are assigned lower setpoints, while cooler converters with higher SOC receive higher setpoints. This dynamic redistribution of power loading balances thermal conditions across all converters while maintaining reliable power supply redundancy.
2Power
If multiple DC-DC power converters operate simultaneously, then power distribution capability is improved, but SOC imbalances between battery modules worsen
Solution Approach 1:
The control algorithm continuously monitors the SOC status of each battery module connected to the DC-DC converters and uses this feedback to adjust converter setpoints. When certain modules show lower SOC, the algorithm reduces the setpoints of converters drawing power from those modules, thereby balancing the discharge rates and maintaining SOC equilibrium across all modules while preserving overall power distribution capability.
3Temperature
If unequal power distribution is assigned to DC-DC converters based on temperature, then thermal balance is improved, but control complexity increases
Solution Approach 1:
The control algorithm changes the operating parameters (output voltage setpoints) of DC-DC converters based on their temperature measurements. By systematically adjusting these electrical parameters in response to thermal conditions, the algorithm achieves thermal balance across converters. The complexity is managed through a structured approach that prioritizes converters based on temperature thresholds and SOC levels, making the control logic implementable despite the multi-parameter nature of the problem.
Data Source
AI summary
An energy storage system for an electric vehicle includes multiple battery modules, multiple DC-DC power converters, a DC bus configured to supply power to one or more loads, and a vehicle control module configured to obtain a temperature of each of the plurality of DC-DC power converters, assign a first output voltage setpoint to a first one of the plurality of DC-DC power converters having a lowest temperature, and in response to the temperature of the first one of the plurality of DC-DC power converters being greater than or equal to the temperature of another one of the plurality of DC-DC power converters, assign a second output voltage setpoint to a second one of the plurality of DC-DC power converters, and reduce the output voltage setpoint of the first one of the plurality of DC-DC power converters to a value less than the second output voltage setpoint.