Single Relay Battery Control System for Overcharge Protection
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Solution Overview
Problem
Current battery management systems face challenges in accurately monitoring the state of charge of lithium batteries due to their non-linear discharge profile, leading to potential overcharging or over-discharging, and require complex and costly relay systems for protection.
Innovation Solution
An automatic battery control system that uses a parallel resistor with a microprocessor and optocouplers to automatically switch between charging and discharging modes, eliminating the need for manual resets and reducing component complexity by utilizing a single relay contactor and transistor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If two relays or contactors are used for over-charge and under-charge protection, then battery protection is achieved, but system complexity and cost increase
Solution Approach 1:
The patent combines the functions of two separate relays (over-charge protection relay and under-charge protection relay) into a single relay with two contactors. This merging reduces component count and system complexity while maintaining the dual protection functions. The single relay uses a common coil that can control both contactors, eliminating the need for separate relay assemblies and reducing wiring complexity.
Solution Approach 2:
The single relay is designed with multi-functionality to perform both over-charge protection and under-charge protection tasks. The relay's contactor arrangement allows it to isolate the battery from both the charger (over-charge protection) and the load (under-charge protection), making one component perform the work of two separate protection devices.
2Ease of operation
If voltage monitoring is used for lithium batteries, then power monitoring is simplified, but state of charge measurement precision deteriorates due to non-linear discharge profile
Solution Approach 1:
The patent introduces an intermediary computational layer that processes the voltage measurement data. Instead of directly using voltage readings as state of charge indicators, the system uses the voltage data as input to calculate amp-hour discharge, which then serves as the basis for determining state of charge. This intermediary calculation method bridges the gap between simple voltage monitoring and accurate state of charge measurement for lithium batteries with non-linear discharge characteristics.
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 system effectively manages lithium battery state of charge, preventing damage from overcharging or over-discharging, and simplifies the battery management process by automating transitions between charge and discharge modes with reduced component complexity and cost.
Implementation Method 1
the relay potential, either positive or negative, of the parallel resistor is sensed by a difference amplifier and indicated by an optocoupler to a microprocessor
Data Source
AI summary
An automatic battery control system automatically switches from charge to discharge modes with a single relay, thereby preventing the need to manually reset a relay switch due to an over or under voltage situation. An automatic battery control circuit is coupled with a battery management system and a relay contactor is opened and closed by a signal from the battery management system. The battery management system monitors a state of charge of the battery unit as well as current flow to and from a battery unit. A parallel resistor is configured across the input and output sides of the single relay contactor and the voltage drop across the resistor indicates a connection to either a charging power source or a load. The connection is communicated to the battery management system by an optocoupler and if the battery unit has an acceptable state of charge, the relay contactor is closed.