Battery Module Pressure Control for Accurate Cell Balancing
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Solution Overview
Problem
Existing battery control systems fail to consider pressure control during battery balancing, leading to inaccurate balancing due to self-discharge and changes in electrical resistance, which affects the ability to apply appropriate pressure for charging and discharging.
Innovation Solution
The system discharges battery cells to balance remaining discharge capacities and applies pressure to a battery module along its stacking direction before balancing, using a pressure application mechanism to maintain optimal pressure for charging and discharging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pressure control is not applied during battery balancing, then the control system can operate without additional pressure control mechanisms, but the electrical resistance of the battery may deviate from the appropriate range due to self-discharge and contraction, reducing balancing accuracy
Solution Approach 1:
The pressure application mechanism applies pressure to the battery module before balancing begins and maintains it throughout the balancing process. This preliminary action ensures that the battery cells remain in an expanded state with appropriate electrical resistance, preventing resistance deviation caused by self-discharge and contraction during the balancing operation.
2Reliability
If pressure is applied to the battery module before balancing, then the electrical resistance remains appropriate for charging and discharging, but the system requires additional pressure control mechanisms and complexity
Solution Approach 1:
The pressure application mechanism is designed to serve multiple functions: it applies pressure during charging, discharging, and balancing operations, and can adjust pressure based on the battery's state of charge and operational requirements. This multi-functionality reduces the need for separate pressure control systems for different operations.
Solution Approach 2:
The control unit monitors the battery's state and adjusts the pressure applied by the pressure application mechanism accordingly. During balancing, when self-discharge and contraction occur, the control unit increases pressure to maintain appropriate electrical resistance, creating a feedback loop that ensures reliable charging and discharging performance.
3Adaptability or versatility
If the control system is stopped and then restarted, then the vehicle can be parked and restarted, but the battery self-discharges and contracts during the stop, causing electrical resistance to deviate and reducing balancing accuracy
Solution Approach 1:
When the control system is restarted after being stopped, the pressure application mechanism immediately applies pressure to the battery module before balancing begins. This preliminary action compensates for the contraction that occurred during the stop period due to self-discharge, ensuring that the battery cells are in the appropriate expanded state for accurate balancing measurements.
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
Improves the accuracy of battery balancing by ensuring the electrical resistance of battery cells is within an appropriate range for charging and discharging, reducing start-up time and maintaining pressure within optimal limits.
Implementation Method 1
pressing the battery module along a stacking direction of the battery cells before balancing begins
Data Source
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AI summary
A battery control system (1) includes: pressure application means (16) that applies pressure to a battery module (2) by pressing the battery module (2) along a stacking direction of battery cells (21) having a negative electrode including a solid electrolyte and lithium; a controller (10) that adjusts the value of the pressure by controlling the pressure application means (16); and discharge means (15) that executes balancing of remaining discharge capacities among the battery cells (21) in the battery module (2); wherein the controller (10) starts a first pressurization control for increasing the pressure by the pressure application means (16) to a predetermined pressure or higher before the balancing is started.