Battery Control System Residual Capacity Estimation
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Solution Overview
Problem
Existing battery control systems face challenges in preventing the forced correction of residual capacity estimates due to voltage fluctuations, leading to inconvenient and inaccurate displays of battery status for users.
Innovation Solution
A battery control system that measures voltages and currents of connected battery units, identifies the minimum capacity unit, sets reference and alarm voltage values, and outputs a signal to reduce discharge current when the minimum capacity unit's voltage reaches the alarm condition, thereby preventing forced correction of residual capacity estimates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the battery control system continues discharge when voltage drops to reference voltage, then productivity is improved, but measurement precision deteriorates due to forced correction of residual capacity estimates
Solution Approach 1:
The system performs preliminary action by outputting a first signal to reduce discharge current when the minimum capacity unit voltage reaches the alarm voltage value (which is higher than the reference voltage value). This preventive measure avoids the voltage dropping to the reference voltage level that would trigger forced correction, thereby maintaining both continuous discharge capability and measurement precision.
2Measurement precision
If discharge current is reduced when alarm condition is met, then measurement precision is improved, but productivity deteriorates due to interrupted discharge
Solution Approach 1:
The system applies partial action by reducing the discharge current rather than completely stopping discharge when the alarm condition is met. The load control unit reduces current to a level that prevents voltage from reaching the reference voltage threshold, maintaining partial discharge functionality while ensuring measurement precision.
3Reliability
If the system reduces discharge current to prevent voltage drop, then reliability is improved, but device complexity increases due to additional control mechanisms
Solution Approach 1:
The system implements feedback control by continuously monitoring the voltage of the minimum capacity unit and comparing it against the alarm voltage value. When the alarm condition is satisfied, the battery control unit outputs a first signal to the load control unit, which adjusts the discharge current accordingly. This closed-loop feedback mechanism ensures reliability while keeping the control logic relatively simple.
Data Source
AI summary
A measurement unit (200) measures voltages and currents of battery cells (100). A battery control unit (400) calculates a present estimation value of a residual capacity of the battery cells (100) by integrating the currents. The voltages of the battery cells (100) are set to a reference voltage value V1 serving as a trigger of a process of correcting the estimation value of the residual capacity and an alarm voltage value Va which is a voltage higher than the reference voltage value. In addition, the battery control unit (400) continues discharge of all the battery cells (100), as it is, when an alarm condition in which a voltage of a minimum capacity cell is equal to or less than the alarm voltage value is not satisfied, and outputs a first signal when the voltage of the minimum capacity cell satisfies the alarm condition.