Battery Cell Overcharge Limit Device for Hybrid Vehicles
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Solution Overview
Problem
Hybrid/electric vehicle batteries face challenges in managing cell pressure and voltage thresholds to prevent overcharge and maintain efficient operation, as existing systems lack effective mechanisms to individually disconnect faulty cells and balance charge across the battery pack.
Innovation Solution
The integration of an overcharge limit device with switches and fuses, connected to an electrical circuit and a controller, which short circuits and disconnects cells exceeding pressure thresholds, and a controller that monitors voltage, temperature, and time thresholds to manage cell operation and charge balancing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the overcharge limit device disconnects individual cells exceeding pressure thresholds, then battery safety and reliability are improved, but device complexity increases due to additional switches and fuses
Solution Approach 1:
The battery system is divided into individual cell modules, each with its own overcharge limit device comprising a switch and fuse. This segmentation allows independent monitoring and protection of each cell, enabling the system to isolate only the faulty cell while maintaining operation of healthy cells, thus improving reliability without requiring complete system shutdown.
Solution Approach 2:
The overcharge limit device acts as an intermediary between the battery cells and the electrical circuit. The switch and fuse serve as intermediate components that automatically intervene when a cell exceeds pressure thresholds, providing protection without requiring direct complex control system intervention, thereby balancing safety with manageable device complexity.
2Productivity
If the controller discontinues control of faulty cells and maintains operation of healthy cells, then productivity is improved by maintaining vehicle operation, but measurement precision requirements increase to accurately identify faulty cells
Solution Approach 1:
The controller continuously monitors voltage, temperature, and current of each battery cell and uses this feedback to identify cells exceeding pressure thresholds. The system adjusts control based on real-time measurements, discontinuing control of faulty cells while maintaining operation of healthy cells, enabling productive continuous operation with precise fault identification.
Solution Approach 2:
The system replaces manual or mechanical fault detection methods with electronic sensing and computational analysis. The controller uses voltage decrease detection, temperature monitoring, and time-based analysis to precisely identify faulty cells, enabling automatic differentiation between healthy and faulty cells without mechanical intervention.
3Reliability
If the system monitors voltage decrease rate and time thresholds to distinguish switch-induced faults from other battery faults, then reliability of fault diagnosis is improved, but device complexity increases due to additional monitoring parameters
Solution Approach 1:
The system pre-establishes voltage thresholds, time thresholds, and temperature thresholds based on expected switch-induced fault characteristics. By having these criteria predetermined, the controller can quickly and reliably diagnose faults without requiring complex real-time analysis, improving diagnostic reliability while keeping monitoring complexity manageable through pre-configured parameters.
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 solution ensures safe and efficient operation by discontinuing control of faulty cells, maintaining operation of healthy cells, and adjusting power output limits, thereby preventing damage and ensuring reliable propulsion.
Implementation Method 1
Each switch is configured to short circuit one of the plurality of cells in response to an internal pressure of the one of the plurality of cells exceeding a pressure threshold
Implementation Method 2
Each fuse is configured to disconnect one of the plurality of cells from the circuit in response to the one of the plurality of cells being short circuited
Data Source
AI summary
A vehicle includes an electric machine, a battery, an electrical circuit, an overcharge limit device, and a controller. The electric machine is configured to propel the vehicle. The battery has a plurality of cells and is configured to provide electrical power to the electric machine. The electrical circuit is configured to deliver the electrical power from the battery to the electric machine. The overcharge limit device is configured to individually disconnect each of the plurality cells from the circuit in response to an internal pressure of a respective cell exceeding a pressure threshold. The controller is programmed to, in response to detecting a first set of parameters that are indicative of a first of the cells being disconnected from the electrical circuit via the overcharge limit device, discontinue control the first of the cells.