Energy Storage Cell Heating via High-Frequency Alternating Transfer
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Solution Overview
Problem
Series-connected battery modules in energy storage devices for electric vehicles are prone to failure and power reduction due to temperature-dependent internal resistance, leading to inefficiencies and potential system failures, especially at low temperatures.
Innovation Solution
A method involving high-frequency alternating electrical energy transfer between energy storage branches to generate heat loss, which heats the energy storage cells without additional heating components, utilizing coupling devices to selectively switch and bypass energy storage modules, ensuring effective operation at low temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If series-connected battery modules are used to meet power and energy demands, then the power and energy capacity is improved, but the reliability deteriorates because the entire string fails when a single module fails
Solution Approach 1:
The battery system is divided into multiple independent parallel strings, each containing series-connected battery modules. Each string can operate independently, so if one string fails, the others continue to provide power. This segmentation transforms the single-point-failure series architecture into a redundant parallel architecture, improving reliability while maintaining power capacity through multiple active strings.
2Adaptability or versatility
If battery modules operate at low temperatures, then the system can function in cold environments, but the internal resistance increases causing power reduction and potential failure
Solution Approach 1:
A periodic heating method is implemented where battery modules are alternately connected to heating circuits at regular intervals. This periodic connection allows heat to be generated and distributed throughout the battery system over time, raising the temperature of all modules including those in cold environments. The periodic action enables cold environment operation while preventing the sustained high internal resistance that would occur at low temperatures.
3Temperature
If additional heating components are added to heat energy storage cells, then the temperature control is improved, but the device complexity increases
Solution Approach 1:
The battery modules serve dual functions: they act as both energy storage devices and heating sources. By connecting battery modules to heating circuits through switching devices, the same battery modules that store energy also generate heat when needed. This multi-functionality eliminates the need for separate heating components, maintaining temperature control capability while avoiding the increased device complexity that would result from adding dedicated heating elements.
Solution Approach 2:
The battery system heats itself by utilizing its own modules as heating sources. When certain battery modules are connected to heating circuits, they generate heat that warms other battery modules in the system. This self-service heating approach eliminates external heating components, simplifying the overall system while maintaining effective temperature control across all battery modules.
4Device complexity
If high-frequency alternating energy transfer is used to heat cells, then external heating components are eliminated, but energy loss occurs during the transfer process
Solution Approach 1:
The energy loss that occurs during high-frequency alternating transfer between battery modules is converted into a beneficial heating effect. Instead of treating the transfer loss as wasted energy, the system utilizes this loss to generate heat within the battery modules themselves. This approach eliminates external heating components and simplifies the system while the energy loss serves the useful purpose of temperature control, effectively converting a harmful effect into a beneficial one.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach maintains the effectiveness of energy storage cells by reducing internal resistance and ensuring full power delivery without external heating, while preventing undesired torques in the electric machine, allowing for efficient operation during normal conditions and low-temperature starts.
Implementation Method 1
A method involves high-frequency alternating electrical energy transfer between energy storage branches to generate heat loss, which heats the energy storage cells
Data Source
AI summary
A method for heating energy storage cells of an energy storage system configured to generate an n-phase supply voltage. The energy storage system including n energy supply branches connected in parallel. Each energy supply branch coupled between an output connection and an equipotential frame, and each of the energy supply branches including a plurality of series-connected energy storage modules. Each energy storage module including an energy storage cell module having at least one energy storage cell and a coupling device having coupling elements configured to selectively connect or bridge the energy storage cell module in a respective energy supply branch. The method includes connecting the output connections of the energy storage system to input connections of an n-phase electrical machine, and coupling the output connections via a neutral point of the electrical machine.