Vehicle Power Supply Offset Correction
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Solution Overview
Problem
Existing power supply systems for vehicles face challenges in accurately correcting offset errors in current sensors, leading to potential overcharging or overdischarging of batteries due to temperature-induced fluctuations in offset errors, which can result in incorrect charge/discharge control, especially at low temperatures.
Innovation Solution
A power supply system that includes a current sensor, a voltage sensor, and a controller that calculates a control current value by subtracting an offset value from the detected current sensor value, with the controller determining whether the battery is being charged or discharged based on both the current sensor and voltage sensor outputs, and adjusting the offset value to ensure accurate determination, thereby preventing overcharging or overdischarging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If offset correction is performed using a stored offset value, then the initial measurement accuracy is improved, but the accuracy deteriorates as temperature changes cause the actual offset error to deviate from the stored value
Solution Approach 1:
The system continuously monitors the battery's state of charge (SOC) and compares it with the expected SOC based on current integration. When a deviation is detected, the system adjusts the offset value to correct the discrepancy, creating a closed-loop feedback mechanism that maintains measurement accuracy despite temperature variations
Solution Approach 2:
The offset value is dynamically adjusted based on temperature conditions and SOC deviations. The system changes the offset parameter from a fixed stored value to a variable that adapts to environmental conditions, specifically modifying it when the SOC deviation exceeds a predetermined threshold
2Measurement precision
If continuous offset correction is performed to maintain high accuracy, then measurement precision is improved, but processing time increases and system complexity increases
Solution Approach 1:
Instead of continuously adjusting the offset value, the system performs correction only when necessary - specifically when the SOC deviation exceeds a predetermined threshold. This partial action approach maintains accuracy when needed while avoiding unnecessary processing during normal operating conditions
Solution Approach 2:
The offset correction is performed periodically based on SOC monitoring cycles rather than continuously. The system checks SOC at intervals and adjusts the offset value only when the deviation threshold is exceeded, creating a periodic correction rhythm that balances accuracy with processing efficiency
Data Source
AI summary
A power supply system includes a controller. The controller is configured to; a) control charging and discharging of an electrical storage device upon reception of an output of a current sensor and a voltage sensor, b) calculate a control current value by subtracting an offset value from a detected value of the current sensor, c) calculate a first determination result and a second determination result, respectively obtained by determining whether the electrical storage device is being charged or discharged based on the control current value, and based on a change in a remaining amount of charge of the electrical storage device, and d) when the first determination result and the second determination result differ from each other, change the offset value such that the first determination result coincides with the second determination result.