Series Battery Charging with Cell Bypass Current Continuity
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Solution Overview
Problem
The existing battery charging and discharging devices face challenges in managing the difference in capacities between multiple cells connected in series, leading to discontinuity issues during charging and discharging, and overcharging of individual cells.
Innovation Solution
A battery charging and discharging device is designed with a main power conversion unit for charging and discharging multiple cells in series, auxiliary power conversion units for individual cell management, and a control unit for constant voltage control and bypassing of cells to prevent overcharging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If cells are connected in series and charged/discharged en bloc using high voltage power conversion device, then power conversion efficiency is improved and wire loss is reduced, but cell capacity differences cause discontinuity intervals when bypassing cells
Solution Approach 1:
The patent introduces a bridge circuit as an intermediary component that enables seamless bypassing of cells during charging/discharging. The bridge circuit includes switches and capacitors that temporarily store and transfer charge, allowing failed or low-capacity cells to be bypassed without creating discontinuity intervals in the main current flow through the series-connected cells.
2Volume of stationary object
If cells are connected in series and charged/discharged en bloc, then equipment capacity and volume are reduced, but individual cells may be overcharged due to capacity differences
Solution Approach 1:
The patent implements a control system that continuously monitors the voltage and charge state of each individual cell in the series connection. When a cell reaches its maximum charge limit or shows signs of overcharging, the control system activates the bridge circuit to bypass that specific cell, preventing overcharging while maintaining the series connection configuration for the remaining cells.
3Adaptability or versatility
If relay is added for bypassing cells, then cell capacity differences can be managed, but current discontinuity intervals occur during transfer process
Solution Approach 1:
The patent designs the bridge circuit to maintain continuous current flow during cell bypass operations. By using capacitors to store charge temporarily and switches to redirect current paths, the bridge circuit ensures that the bypassing operation does not interrupt the useful action of charging or discharging the battery pack, eliminating discontinuity intervals that would occur with simple relay-based bypassing.
Data Source
AI summary
Proposed is a battery charge/discharge device which solves a discontinuity problem caused by a battery capacity difference in a constant-current mode of collectively charging or discharging multiple batteries connected in series. The proposed device comprises: a main power conversion unit which charges or discharges multiple batteries connected in series; multiple auxiliary power conversion units which charge or discharge the multiple batteries, respectively; and a control unit which controls the main power conversion unit to perform constant-voltage control of the multiple batteries on the basis of a total voltage obtained by summing the voltages of the multiple batteries in a constant-voltage interval for the multiple batteries, and controls the multiple auxiliary power conversion units to maintain the voltage of each of the multiple batteries at a target voltage of a corresponding battery.