Parallel Battery String Circuit with Single Protective Device
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Solution Overview
Problem
Existing battery string connection circuits are costly and result in significant electrical losses due to compensating currents between battery strings, which can lead to system failures and safety issues in high-demand applications like electric vehicles and wind turbines.
Innovation Solution
A circuit that connects multiple battery strings in parallel using a single protective device, eliminating compensating currents by ensuring all strings are disconnected or connected simultaneously with a single protective device, and utilizing a bidirectional switching converter to maintain uniform voltage levels, allowing for inexpensive switch selection and reduced electrical losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple pre-charging contactors and resistors are used for each battery string, then the intermediate circuit capacitor can be charged with limited current, but compensating currents flow between battery strings causing heat loss and costs increase
Solution Approach 1:
The patent merges the protective functions for multiple battery strings into a single protective device (contactor) that controls the connection of all battery strings to the intermediate circuit capacitor simultaneously. This eliminates the need for separate pre-charging contactors and resistors for each string, thereby eliminating compensating currents and associated energy losses while maintaining system reliability.
Solution Approach 2:
The single protective device performs multiple functions: it protects all battery strings simultaneously, controls the charging of the intermediate circuit capacitor, and prevents compensating currents between strings. This multi-functional approach reduces component count and eliminates the energy losses associated with redundant protective devices.
2Reliability
If multiple expensive circuit breakers are used for each battery string, then each string can be protected independently, but costs increase significantly
Solution Approach 1:
The patent combines multiple protective functions into a single protective device (contactor) that handles all battery strings simultaneously. This single device replaces what would otherwise require multiple expensive circuit breakers, significantly reducing costs while maintaining independent protection capability through simultaneous operation.
Solution Approach 2:
The single protective device serves as a universal protector for all battery strings, performing the protective function that would otherwise require multiple dedicated circuit breakers. This multi-functional design reduces device complexity and cost while ensuring reliable protection.
3Reliability
If pre-charging resistors are used to limit charging current, then the intermediate circuit capacitor can be charged safely, but electrical losses occur due to compensating currents
Solution Approach 1:
The patent eliminates the need for multiple pre-charging resistors by using a single protective device that simultaneously controls all battery string connections. This removes the source of compensating currents and associated heat losses while maintaining safe charging through the inherent resistance of the single protective device and controlled closing operation.
Data Source
Figure 1~2
AI summary
The invention relates to a circuit for joining a first accumulator line (6) to a second accumulator line (8) from an accumulator (2). Said accumulator (2) is provided for receiving and dispensing electric energy (14) by means of the accumulator lines (6, 8). Each accumulator line (6, 8) has a positive pole and a negative pole for receiving and dispensing electric energy (14). Said circuit (4) comprises at least one first switch (16) which separates and connects two poles of the same type of both accumulator lines (6, 8).