Battery Pack Parallel Connection Using Open-Circuit Voltage Matching
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Solution Overview
Problem
The power limitations of a single battery pack often fail to meet the needs of electrical devices, necessitating parallel connection of multiple battery packs, which is hindered by inaccurate voltage differences and safety concerns due to resistance and temperature variations.
Innovation Solution
A battery parallel system and method that uses a master battery pack to determine and manage the connection of slave battery packs based on open-circuit voltage and temperature conditions, ensuring safe and accurate parallel operation by using a processor to assess and control switch closures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If multiple battery packs are connected in parallel to increase power output, then the power capability is improved, but the voltage difference measurement accuracy deteriorates due to resistance variations
Solution Approach 1:
The patent introduces an intermediary pre-charging circuit with a pre-charging switch between the battery packs and the main parallel connection point. This pre-charging circuit equalizes voltage differences before the main connection is established, preventing measurement errors and current surges that would occur with direct parallel connection of battery packs with different voltages.
2Adaptability or versatility
If battery packs with different voltages are connected in parallel, then the system can accept more battery packs, but safety deteriorates due to potential overcurrent and irreversible damage
Solution Approach 1:
The patent implements preliminary voltage equalization through the pre-charging circuit before the main parallel connection is established. The pre-charging switch closes first to equalize voltages, and only after voltage differences are within safe thresholds does the main parallel connection switch close. This preliminary action prevents overcurrent and irreversible damage while allowing battery packs with initially different voltages to be safely integrated.
Data Source
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AI summary
A battery parallel-connection method, the method including: waking up N battery packs; obtaining parameters of the N battery packs, and determining a master battery pack and remaining N-1 slave battery packs from the N battery packs, wherein the parameters of the battery packs comprise one or more of current, voltage, resistance, temperature, or switch status, and the master battery pack comprises a first processor; and determining, by the first processor, whether a to-be-incorporated battery pack and an incorporated battery pack meet a pre-parallel-connection condition, and sending a switch closing instruction to the to-be-incorporated battery pack when it is determined that the to-be-incorporated battery pack and the incorporated battery pack meet the pre-parallel-connection condition, wherein the pre-parallel-connection condition comprises: condition S1: the to-be-incorporated battery pack triggers no fault, and the incorporated battery pack triggers no fault; and condition S2: an absolute value of a difference between an open-circuit voltage of the to-be-incorporated battery pack and an open-circuit voltage of the incorporated battery pack is less than a first voltage threshold; and the open-circuit voltage of the incorporated battery pack is a minimum open-circuit voltage or a maximum open-circuit voltage in a battery parallel system.