EV Charger Voltage Spike Limiting via IGBT Feedback
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Solution Overview
Problem
Electric vehicle energy storage systems experience voltage spikes during charging, which can lead to undesirable operating conditions and reduced battery lifespan due to sudden increases in system voltage caused by changes in load conditions.
Innovation Solution
Implementing a maximum voltage limit at the charger, determined as a value slightly higher than the system voltage, to prevent voltage surges by trimming excess voltage and maintaining the system within a safe operating range, thereby reducing the impact of transient load changes on the battery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the charging system allows voltage to rise freely during charging, then the charging speed and power transfer efficiency are improved, but the battery may enter undesirable operating regions and suffer reduced lifespan due to voltage spikes
Solution Approach 1:
The system preemptively applies a counter-voltage action by injecting reverse polarity voltage through the IGBT bridge when a voltage spike is detected. This preliminary anti-action prevents the voltage from entering dangerous regions by actively counteracting the spike before it can cause damage to the battery system.
Solution Approach 2:
The voltage spike protection system continuously monitors the DC link voltage and provides feedback control. When the voltage exceeds a predetermined threshold, the control system activates the IGBT bridge to inject counter-voltage, creating a closed-loop feedback mechanism that maintains voltage within safe operating limits while allowing efficient charging.
2Reliability
If the maximum voltage limit is set closer to the system voltage, then the allowable voltage spike margin is reduced improving battery protection, but the system becomes more sensitive to transient load changes
Solution Approach 1:
The system dynamically adjusts the voltage limiting threshold based on operating conditions rather than using a fixed threshold. The control system monitors transient load changes and adapts the maximum voltage limit accordingly, allowing the system to be more protective during steady-state operation while accommodating transient variations when load changes are detected.
Solution Approach 2:
The system changes the voltage threshold parameter dynamically based on system conditions. By adjusting the maximum voltage limit parameter in response to transient load changes, the system maintains optimal protection levels while adapting to varying operational requirements, thus balancing protection with adaptability.
Data Source
AI summary
A method of charging an electric vehicle includes receiving data indicative of the power source system voltage during charging, determining a maximum voltage limit of the power source, and setting the maximum voltage limit as the limiting voltage of the power source. The maximum voltage limit may be the maximum permissible value of the system voltage during the charging.