Parallel Battery Pack Switching Using Voltage Difference to Block Inrush
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Solution Overview
Problem
Connecting battery packs with different voltages in parallel can result in an inrush current, potentially damaging the battery cells and protection circuits, necessitating a method to prevent this inrush current.
Innovation Solution
A battery system with a controller that manages switches, including FETs and body diodes, to control current flow based on voltage differences between battery packs, ensuring that inrush currents are prevented by maintaining switches in appropriate on/off states depending on voltage disparities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If battery packs with different voltages are connected in parallel, then storage capacity is increased, but inrush current occurs that may damage battery cells and protection circuits
Solution Approach 1:
The controller performs preliminary voltage comparison between battery packs before enabling parallel connection. The second controller compares its battery pack voltage with the first battery pack voltage and determines connection timing in advance, preventing inrush current by ensuring voltage compatibility before parallel operation begins
Solution Approach 2:
The second switch acts as an intermediary control element between the battery packs and the parallel connection. It is controlled by the second controller to manage current flow, serving as a protective mediator that prevents direct uncontrolled current flow between battery packs with voltage differences
2Object-affected harmful factors
If switches are added to control current flow between battery packs, then inrush current is prevented, but device complexity increases
Solution Approach 1:
The second controller autonomously performs voltage comparison and automatically controls the second switch based on the voltage difference between battery packs. This self-service mechanism eliminates the need for external complex control circuits, as the controller inherently manages the protection function through its own decision-making logic
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
Effectively prevents inrush currents between battery packs with varying voltages, ensuring safe operation and protecting the battery cells and protection circuits.
Implementation Method 1
the first switch may include a first field effect transistor (FET) connected between the battery module and the second switch on the discharging path
Implementation Method 2
a first body diode that may be connected between both ends of the first FET, the first switch may be configured to: transmit the discharge current of the battery module to the discharging path through the first body diode if turned off
Data Source
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AI summary
A battery system having a plurality of first terminals and a plurality of battery packs connected in parallel between the plurality of first terminals, wherein each of the plurality of battery packs includes a battery module connected between the plurality of first terminals, a first switch on a discharging path between the battery module and one of the first terminals, a second switch on the discharging path that allows or blocks a current flow in the discharging path, and a first controller. If a control signal indicating a turned-on state of the first switch is received from an electronic device equipped with the battery system while the second switch is turned on, the first controller may control the turning of the first switch on/off based on a voltage difference between a first voltage at a first node between the battery module and the first switch and a second voltage at a second node between the second switch and the first terminal.