Parallel Battery Current Limiting Circuit
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Solution Overview
Problem
When multiple types of rechargeable batteries are connected in parallel, circulating currents can flow, exceeding the maximum charge or discharge currents of individual batteries, potentially causing damage due to varying characteristics.
Innovation Solution
An electrical apparatus with a discharge current limiting circuit connected in series with the first rechargeable battery, ensuring that discharge currents do not exceed its maximum capacity, and using a second rechargeable battery with a higher maximum discharge current to prevent excessive current flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If multiple types of rechargeable batteries are connected in parallel to supply power to the electrical apparatus, then the power supply capacity and energy availability are improved, but circulating currents may flow between batteries with different characteristics, causing currents to exceed maximum charge or discharge current limits
Solution Approach 1:
A current limiting circuit is introduced as an intermediary component between the first rechargeable battery and the parallel connection point. This circuit actively monitors and limits the discharge current from the first battery to prevent it from exceeding maximum current limits, thereby blocking the harmful circulating current while allowing the battery to continue contributing power to the system
Solution Approach 2:
The current limiting circuit dynamically adjusts the discharge current parameter of the first rechargeable battery based on its maximum current capability. By changing the current parameter in real-time, the system prevents circulating currents from exceeding safe limits while maintaining optimal power distribution from both battery types
2Reliability
If a discharge current limiting circuit is connected in series with the first rechargeable battery to prevent excessive current flow, then the safety and reliability of the battery system are improved, but the device complexity increases
Solution Approach 1:
The battery system is segmented into distinct current control zones: the first rechargeable battery is placed in series with a dedicated current limiting circuit, while the second rechargeable battery connects directly to the parallel connection point. This segmentation allows targeted current management for each battery type based on their specific characteristics, improving reliability without requiring complex control for the entire system
Solution Approach 2:
The current limiting function is applied locally only to the first rechargeable battery that requires it, rather than implementing a universal current limiting system for all batteries. This local quality approach adds minimal circuit complexity only where necessary, maintaining system reliability while avoiding unnecessary complexity in the overall design
Data Source
AI summary
An electrical apparatus incorporates a first rechargeable battery (11) and a second rechargeable battery (12) connected in parallel with the first rechargeable battery (11), the second rechargeable battery (12) having an allowable maximum discharge current larger than that of the first rechargeable battery (11). The electrical apparatus includes: a power supply path (15a) configured to input power supplied from the first rechargeable battery (11) and from the second rechargeable battery (12) to a load (15); and a discharge current limiting circuit connected serially with the first rechargeable battery (11) and configured to perform control in such a manner that a discharge current flowing from the first rechargeable battery (11) to the second rechargeable battery (12) and/or to the power supply path (15a) does not exceed the maximum discharge current of the first rechargeable battery (11).