Battery Pack Precharge Control for Inrush Current and Circuit Life
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Solution Overview
Problem
The cycle-life of precharge circuits in battery apparatuses is reduced due to frequent overcurrents flowing through precharge resistors during the initial driving of switching circuits, which is not effectively managed by existing precharge circuits.
Innovation Solution
A battery apparatus with parallel-connected battery packs, precharge switches, and control circuits that manage the operation of these switches based on voltage differences between the battery packs and a capacitor, preventing unnecessary precharging by controlling the precharge switches only when the voltage difference exceeds a predetermined threshold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a precharge circuit is used for each switching circuit to prevent inrush current, then the inrush current is prevented, but the cycle-life of the precharge circuit is reduced due to frequent overcurrents
Solution Approach 1:
The patent changes the operational parameters of the precharge circuit by introducing voltage difference thresholds. The precharge switch is controlled based on comparing the battery pack voltage with the capacitor voltage, and the switch operates only when the voltage difference exceeds a predetermined threshold. This parameter-based control reduces unnecessary precharging operations, thereby extending the cycle-life of the precharge circuit while maintaining inrush current prevention capability.
2Reliability
If precharge switch is always activated to ensure capacitor precharging, then the capacitor is always precharged, but unnecessary precharging occurs reducing circuit component life
Solution Approach 1:
The patent implements a feedback control mechanism where the precharge control circuit continuously monitors the voltage difference between the battery pack and the capacitor. Based on this feedback information, the control circuit intelligently determines whether to activate the precharge switch. This feedback-based approach ensures the capacitor is precharged only when necessary (when voltage difference exceeds threshold), avoiding unnecessary operations that would reduce circuit component life.
Data Source
AI summary
In a battery apparatus, a first precharge switch is connected between a terminal of a first battery pack and a capacitor of an external apparatus, and a second precharge switch is connected between a terminal of a second battery pack and the capacitor. A first precharge control circuit controls an operation of the first precharge switch based on a difference between a voltage of the first battery pack and a voltage of the capacitor, and a second precharge control circuit controls an operation of the second precharge switch based on a difference between a voltage of the second battery pack and the voltage of the capacitor. A processor transfers a first control signal for controlling the first precharge switch to the first precharge control circuit, and transfers a second control signal for controlling the second precharge switch to the second precharge control circuit.