Vehicle Battery Charge Rate Output During Stops for Accurate SOC
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Solution Overview
Problem
Existing on-vehicle systems face challenges in accurately measuring the charge level of secondary batteries, especially when the vehicle is in motion or auxiliary machines are consuming power, leading to potential inaccuracies in capacity estimation.
Innovation Solution
An on-vehicle system that acquires a signal indicating the voltage of the secondary battery, uses external electric power to control output electric power such that stored electric power remains constant when the vehicle stops, allowing for precise output of the charge rate and degradation assessment based on voltage changes at different stop times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If charge level is measured during vehicle operation or auxiliary machine operation, then continuous monitoring is achieved, but measurement accuracy deteriorates
Solution Approach 1:
The system performs charge level measurements during vehicle stops when the battery is in a stable state with no current flow, before the vehicle resumes operation. This preliminary measurement during idle periods ensures high accuracy by avoiding the interference of charging/discharging currents, while still providing continuous monitoring capability through multiple measurement points throughout operation cycles.
2Speed
If voltage measurement is performed during charging or discharging, then real-time data acquisition is achieved, but measurement accuracy deteriorates due to internal resistance voltage
Solution Approach 1:
The system periodically measures battery voltage during vehicle stops when charging/discharging current is zero, eliminating the voltage drop caused by internal resistance. This periodic measurement approach during idle periods provides accurate charge level data without the measurement errors that occur during active charging or discharging operations.
3Reliability
If multiple measurements are taken during operation to improve accuracy, then measurement reliability improves, but time consumption increases
Solution Approach 1:
The system performs multiple voltage measurements during vehicle stops before capacity estimation, when the battery is in a stable state. By conducting these preliminary measurements during idle periods rather than during operation, the system achieves reliable capacity estimation without adding time loss to the vehicle's operational time, as the measurements utilize otherwise idle time periods.
Data Source
AI summary
An on-vehicle system according to an aspect of the present invention includes: an acquisition part that acquires a signal indicating a voltage of a secondary battery which is mounted on a vehicle; an electric power supply part that uses electric power which is supplied from an external electric power supply device and that supplies the electric power to the secondary battery or an auxiliary machine mounted on the vehicle; and an output part that outputs a charge rate of the secondary battery based on the signal indicating the voltage of the secondary battery which is acquired by the acquisition part, wherein the electric power supply part controls output electric power such that stored electric power of the secondary battery is constant in a case where the vehicle stops and the charge rate of the secondary battery is output.