Power Converter Capacitor Precharging to Prevent Pulse Current Damage
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Solution Overview
Problem
In electric vehicle charging, the normal operation of the charging process is compromised due to high pulse currents generated by capacitors in power conversion devices, which can damage components and lead to charging security issues.
Innovation Solution
A pre-charging method for power conversion devices that involves charging a capacitor using the voltage from the power battery, ensuring that the capacitor does not generate high pulse currents during the charging process by transmitting a minimum demand current value when pre-charging is not complete, thereby preventing damage and ensuring charging security.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the charging process starts immediately without pre-charging the capacitor, then the charging speed is faster, but high pulse currents are generated that can damage components and compromise charging security
Solution Approach 1:
The patent applies preliminary action by implementing a pre-charging phase before the main charging process. The power conversion device charges the capacitor to a predetermined voltage threshold before normal charging begins, preventing high pulse currents from damaging components while enabling subsequent fast charging operation.
2Reliability
If the capacitor is pre-charged to a high voltage threshold, then the risk of high pulse currents is reduced, but the pre-charging time increases
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the pre-charging threshold voltage based on system conditions. The threshold is set to a predetermined value that balances safety requirements with time efficiency, allowing the capacitor to be charged sufficiently to prevent high pulse currents while minimizing unnecessary pre-charging duration.
3Productivity
If the power conversion device transmits the actual demand current value to the charging apparatus, then the charging efficiency is optimized, but the capacitor may generate high pulse currents that damage components
Solution Approach 1:
The patent applies preliminary action by pre-charging the capacitor before transmitting the actual demand current value to the charging apparatus. This ensures the capacitor is ready to handle the full charging current without generating damaging pulse currents, thereby enabling optimized charging efficiency while preventing component damage.
Solution Approach 2:
The patent applies the intermediary principle by using the capacitor as a buffer between the charging apparatus and the power battery. The capacitor absorbs and smooths current fluctuations, allowing the transmission of actual demand current values for optimized charging efficiency while preventing high pulse currents from reaching and damaging downstream components.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The pre-charging method effectively prevents high pulse currents, ensuring normal operation and charging security by controlling the output current to the capacitor, thus maintaining the integrity of the charging process.
Implementation Method 1
performing the pre-charging includes charging a capacitor in the power conversion device
Data Source
AI summary
Embodiments of the present application provide a pre-charging method of a power conversion device and a power conversion device. The power conversion device is used for a power conversion between a charging pile and a power battery and the method includes: receiving, by the power conversion device, a first message transmitted by a battery management system of the power battery, where the first message is used to indicate a charging readiness of the battery management system; and forwarding, by the power conversion device, the first message to the charging pile and performing a pre-charging, where the pre-charging includes charging a capacitor in the power conversion device. The technical solution in embodiments of the present application is capable of ensuring normal performing of a charging process.