Battery Module Switching Circuit for Charge Control
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Solution Overview
Problem
High-voltage batteries used in electric and hybrid vehicles face challenges in charge and discharge control due to the high voltage requirements, which can damage cells when exceeding allowable voltage ranges, and existing solutions either require high-breakdown voltage transistors or omit charge/discharge control, limiting battery lifespan and functionality.
Innovation Solution
The battery is divided into modules with switchable and non-switchable submodules, where submodule switching circuits allow cells to be selectively connected or disconnected, using field effect transistors to manage voltage and prevent overcharging/over-discharging, and a control unit balances the state of charge across modules.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If charge and discharge control circuitry is implemented in high-voltage batteries, then cell damage from overcharging/over-discharging is prevented, but device complexity increases due to high-breakdown voltage transistor requirements
Solution Approach 1:
The battery is divided into multiple battery modules, each with its own submodule switching circuits. This segmentation allows each module to be controlled independently with lower-voltage transistors, avoiding the need for high-breakdown voltage transistors while maintaining protection against overcharging and over-discharging.
Solution Approach 2:
Submodule switching circuits act as intermediaries between the control unit and individual cells. These switching circuits include bypass connections that can be activated to protect cells from voltage extremes, providing cell protection without requiring the control unit to directly handle high-voltage switching.
2Reliability
If charge balancing circuits are added to balance individual cell charges, then cell capacity differences are compensated, but device complexity and internal resistance increase
Solution Approach 1:
The charge balancing function is merged with the existing submodule switching circuits. The same switching elements used for voltage control also perform charge balancing by selectively connecting or disconnecting submodules, eliminating the need for separate balancing circuitry and reducing overall complexity.
Solution Approach 2:
The submodule switching circuits serve multiple functions: they control voltage levels, prevent overcharging/over-discharging, and balance charge across cells. This multi-functionality reduces the need for additional dedicated circuits, thereby reducing internal resistance and complexity.
3Reliability
If high-breakdown voltage transistors are used for charge/discharge control, then voltage control is achieved, but manufacturing cost and device complexity increase
Solution Approach 1:
By segmenting the battery into modules with multiple submodules, the voltage control requirement for each transistor is reduced. Standard low-breakdown voltage transistors can be used in series combinations to achieve the required overall voltage control, significantly reducing manufacturing cost compared to using high-breakdown voltage transistors.
4Device complexity
If battery control circuit is omitted to reduce complexity, then device complexity decreases, but battery lifespan and functionality are limited
Solution Approach 1:
The battery system performs self-protection through automatically activating bypass connections when voltage thresholds are exceeded. This self-service mechanism protects cells from damage without requiring complex continuous monitoring circuitry, thereby extending battery lifespan while maintaining relatively simple control.
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 reduces the complexity of circuitry, minimizes internal resistance, and prevents cell damage by allowing voltage and charge balancing, extending battery lifespan and maintaining functionality beyond 80% capacity.
Implementation Method 1
Each submodule comprises a first and a second submodule terminal and at least one cell. At least two submodules in each battery module are switchable submodules comprising a submodule switching circuit. The submodule switching circuit is switchable between a first state and a second state.
Data Source
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AI summary
A battery and a method of operating a battery are provided. The battery comprises at least one battery module. Each battery module comprises a plurality of submodules electrically connected in series. Each submodule comprises a first and a second submodule terminal and at least one cell. At least one submodule in each battery module is a switchable submodule comprising a submodule switching circuit. The submodule switching circuit is switchable between a first state and a second state. The submodule switching circuit electrically connects the at least one cell of the switchable submodule between the first and the second submodule terminal of the switchable submodule when the submodule switching circuit is in the first state. The submodule switching circuit provides an electrical bypass connection between the first and the second submodule terminal of the switchable submodule and the at least one cell of the switchable submodule is electrically disconnected from at least one of the first and the second submodule terminal when the switching circuit is in the second state. The battery further comprises a control unit for operating the switching circuit in the at least one switchable submodule of each module.