Battery Voltage Balancing via Periodic Switching
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Solution Overview
Problem
Existing battery pack systems with series-connected storage batteries face issues of voltage variations leading to cross currents and high power consumption due to the use of current control elements with adjustable resistance values.
Innovation Solution
An adjusting device with switches and detection means is connected between storage battery units and a load, controlling the ON/OFF state of switches to adjust voltage differences by varying the ON time intervals based on current detection results, specifically shortening the ON time for battery units with currents differing significantly from the highest current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If current control elements with adjustable resistance values are used to reduce voltage variations among series cell units, then voltage balance is improved, but power consumption increases
Solution Approach 1:
The patent implements periodic switching of current control elements in cycles consisting of a detection period and an adjustment period. During the detection period, all switches are ON to detect currents from each series cell unit. During the adjustment period, switches are selectively ON or OFF based on detected current values to balance voltages. This periodic operation allows voltage balancing while reducing average power consumption compared to continuous resistance adjustment.
Solution Approach 2:
The patent performs current detection during the detection period before the adjustment period begins. This preliminary detection of current values allows the control device to pre-determine which switches should be ON or OFF during the subsequent adjustment period, enabling proactive voltage balancing before significant voltage deviations occur.
2Ease of operation
If resistance values of current control elements are increased to control current magnitude, then current control capability is improved, but power loss increases
Solution Approach 1:
The patent dynamically changes the resistance values of current control elements by switching them ON or OFF based on real-time current detection results. Instead of using fixed high resistance values, the system adapts resistance dynamically through switching, maintaining current control capability while minimizing power loss by using low resistance paths when switches are ON.
Data Source
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AI summary
An adjusting device that is connected to a load and to a plurality of storage battery units that are connected together in parallel and that adjusts voltage differences among the plurality of storage battery units includes: for each of the storage battery units, a switch that is provided between a storage battery unit and the load that is turned ON during detection intervals for detecting current from the storage battery unit, a detection means that detects the current supplied from each of the storage battery units during the detection interval, and an adjusting means that, based on the detection results of the detection means, controls the ON/OFF states of switches during the adjustment intervals for adjusting voltage differences such that the voltage differences among the plurality of storage battery units are decreased.