Vehicle Charger DC Link Voltage Control for Reverse In-Rush
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Electric vehicle chargers face issues with reverse in-rush current when connecting to vehicle batteries, which can impact charging performance and duration, and existing methods using current sensors are prone to noise interference and delayed detection.
Innovation Solution
A controller that uses a voltage sensor to detect the DC link voltage and adjusts the output voltage of the charger to prevent reverse in-rush current by comparing it with a reference voltage, employing a dual active bridge circuit to isolate the voltage sensor from the output and quickly detect voltage rises indicative of in-rush currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a current sensor is used to detect in-rush current, then the detection can be performed, but the detection is prone to noise interference and delayed detection
Solution Approach 1:
The patent introduces a voltage sensor as an intermediary device to indirectly detect in-rush current by monitoring voltage drops across a sense resistor, rather than directly measuring current. This intermediary approach isolates the detection system from the high-current path, eliminating noise interference and improving detection reliability while maintaining measurement accuracy.
2Productivity
If the charger output voltage is increased to prevent reverse in-rush current, then the charging performance is improved, but the system complexity increases
Solution Approach 1:
The controller proactively increases the charger output voltage before connecting to the vehicle battery, establishing a voltage headroom that prevents reverse in-rush current. This preliminary action eliminates the need for complex real-time current monitoring and reactive control, simplifying the system while improving charging performance.
3Ease of operation
If DC contactors are closed to connect charger to vehicle battery, then the charging connection is established, but reverse in-rush current flows from battery to charger
Solution Approach 1:
The controller applies preliminary anti-action by pre-charging the DC link capacitor and establishing output voltage higher than the battery voltage before closing the DC contactors. This prevents the harmful reverse in-rush current from flowing into the charger when the connection is made, eliminating the need for complex current limiting circuits or slow-acting contactors.
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
This solution enables faster and more reliable detection of reverse in-rush currents, reducing their impact on charging performance and ensuring efficient battery charging by quickly adjusting the output voltage to match the battery voltage.
Implementation Method 1
The controller can compare this voltage with a reference voltage, and then increase an output voltage of the charger based on the comparison
Implementation Method 2
employing a dual active bridge circuit to isolate the voltage sensor from the output and quickly detect voltage rises indicative of in-rush currents
Data Source
AI summary
Controlling reverse in-rush current for vehicle chargers is provided. A system can include a controller to determine a first value of voltage. The voltage can be of or associated with a DC link of a charger to output power to a battery of an electric vehicle. The controller can detect an in-rush current from the battery to the charger. The detection can be responsive to the first value of voltage at the DC link being greater than a reference value of voltage established for the DC link.