EV Charge Control Apparatus Preventing Battery Overvoltage
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Solution Overview
Problem
Existing charge control systems for electric vehicles fail to promptly manage temporary increases in charging current, leading to overvoltage states in traction batteries, especially when electric devices like water heaters are deactivated during charging.
Innovation Solution
A charge control apparatus and method that includes an instruction unit to detect a decrease in electric device load, a restriction unit to limit the charging current, and a load decreasing unit to gradually decrease the electric device load after the charging current has been restricted, preventing overvoltage by synchronizing the reduction in charging current with the decrease in electric device load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the charging current is decreased when the electric device is stopped, then the overvoltage state of the traction battery is prevented, but it takes a certain amount of time to decrease the charging current, causing the decrease timing to be too late and the overvoltage state to occur anyway
Solution Approach 1:
The patent applies preliminary action by detecting the stop instruction of the electric device in advance and starting to decrease the charging current immediately upon detection, before the actual stop occurs. This proactive approach ensures that the charging current is reduced in time to prevent overvoltage, eliminating the delay that occurs when waiting for the device to actually stop before responding.
2Productivity
If the charging current is controlled by a charge control circuit, then the charging process is managed, but the charging current cannot follow up a rapid increase when the electric device is stopped, causing temporary overvoltage
Solution Approach 1:
The patent implements feedback control by continuously monitoring the charging current and comparing it with the required current based on the electric device's actual power consumption. When a discrepancy is detected (indicating the device has stopped), the system immediately adjusts the charging current downward, creating a closed-loop control system that responds rapidly to load changes and prevents overvoltage conditions.
Data Source
AI summary
A charge control apparatus for an electric vehicle that includes: a traction motor; a traction battery to which charging current is supplied from an external power source and that supplies current to the traction motor; and an electric device actuated by part of the charging current during charging of the traction battery is provided. The charge control apparatus includes: an instruction unit to instruct decrease of load of the electric device in case that the electric device is actuated during charging of the traction battery; a restriction unit to restrict the charging current after instruction of the decrease of load; and a load decreasing unit for decreasing load of the electric device after restricting the charging current.