Bidirectional EV Charger Self-Test for Short-Circuit Blocking
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Bidirectional chargers for electric vehicles risk damaging the traction battery due to short circuits in the power electronics unit during DC charging, and existing methods for identifying short circuits are inadequate.
Innovation Solution
A self-test method where the power electronics unit is subjected to a self-test voltage equal to or greater than the maximum charging voltage at defined intervals when no vehicle is connected, allowing for detection of short circuits or defects, and blocking the charging terminal if a fault is found, ensuring the battery is not damaged during charging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If bidirectional chargers are used to enable energy feedback to the power supply system, then the utility and versatility of the charger is improved, but the risk of battery damage due to power electronics unit short circuits increases
Solution Approach 1:
The patent applies preliminary action by performing self-tests on the power electronics unit before charging operations begin. The control device executes test sequences that apply test voltages and monitor for short circuits in advance, preventing battery damage before it can occur. This proactive approach addresses the harmful effects of potential short circuits while maintaining bidirectional charging functionality.
2Reliability
If short circuit detection methods are implemented, then the reliability of charging operations is improved, but the device complexity increases
Solution Approach 1:
The patent implements self-service by enabling the power electronics unit to perform self-diagnosis through integrated self-test functions. The control device monitors the unit's own operational parameters and detects short circuits using built-in sensing capabilities, eliminating the need for separate external detection systems. This approach enhances reliability while minimizing additional device complexity.
3Measurement precision
If self-test voltage is applied at maximum charging voltage levels, then the detection precision for short circuits is improved, but the energy consumption and potential harm during testing increases
Solution Approach 1:
The patent applies partial action by using test voltages that reach maximum charging voltage levels only when necessary for definitive short circuit detection. The control device implements a staged testing approach, applying progressively higher test voltages and monitoring for anomalies. This allows precise detection of insulation defects while limiting the duration and magnitude of high-voltage exposure, thereby reducing potential test-induced damage.
Data Source
AI summary
A method is provided for operating a bidirectional charger (1) for DC charging of electric vehicles. The charger (10) has a charging terminal (11) for connecting an electrically driven vehicle and at least one power electronics unit (12) for providing defined charging current and defined charging voltage at the charging terminal (11). The power electronics unit (12) is subjected to a self-test voltage of at least the maximum charging voltage of the charger (10) at defined time intervals for a defined time for performing a self-test when there is no vehicle at the charging terminal (11). A check then is performed to ascertain whether a short circuit or defect is formed at the power electronics unit (12). The charging terminal (11) is enabled for charging a vehicle if no short circuit is found and the charging terminal is blocked for charging a vehicle when a short circuit is established.