Relay Device Voltage Restriction for EV Charging
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Solution Overview
Problem
Existing relay devices fail to prevent abnormal currents such as reverse current and rush current when charging vehicles with different DC charging standards, due to voltage differences between the vehicle's battery and the charging station's output.
Innovation Solution
A relay device that converts control signals between different formats, includes a restriction unit to manage energization based on voltage differences, an acquisition unit to measure voltage values, a determination unit to assess voltage thresholds, and a release unit to adjust energization, along with a backflow prevention diode to prevent current backflow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If control signals are converted between different DC charging standards using a relay device, then compatibility between charging stations and vehicles is improved, but abnormal currents such as reverse current and rush current occur due to voltage differences
Solution Approach 1:
The relay device serves as an intermediary between the charging station and the vehicle, converting control signals between different DC charging standards (CHAdeMO and Combo). The relay device includes a voltage management unit that monitors voltage differences and controls the timing of power transmission, preventing abnormal currents while enabling compatibility between different charging standards
Solution Approach 2:
The relay device performs preliminary voltage verification before enabling power transmission. The voltage management unit checks whether the voltage difference between the charging station and vehicle battery is within a safe range, and only after confirmation does it release the restriction on power supply, preventing rush current and reverse current from occurring at startup
2Reliability
If voltage verification and restriction control are implemented to prevent abnormal currents, then charging safety is improved, but system complexity increases
Solution Approach 1:
The relay device combines multiple functions into a single unit: control signal conversion between different charging standards, voltage difference verification, and power transmission restriction control. By merging these functions into one integrated device, the system achieves improved safety without proportionally increasing overall system complexity
Solution Approach 2:
The voltage management unit automatically monitors voltage differences and controls power transmission restrictions without requiring external intervention. The system self-regulates based on voltage conditions, simplifying the control architecture while maintaining high safety standards
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
Effectively relays control signals between vehicles and charging stations with different standards, preventing abnormal currents and ensuring safe charging by adjusting voltage differences and restricting backflow.
Implementation Method 1
a backflow prevention diode that prevents current from flowing back to the charging station from the battery regardless of control performed by the vehicle based on the control signal
Data Source
AI summary
A relay device provided in vehicle having a battery, converting control signal formats, and relaying same between: a first communications unit that sends and receives control signals in a first format relating to charging; and second communications unit that supplies DC voltage, is provided in a charging station that charges battery, and sends and receives control signals in a second format relating to charging. The relay device includes: a limiting unit that limits power supplied between charging station and battery, regardless of vehicle side control performed on control signals' basis; an acquisition unit that obtains DC voltage supplied by charging station and obtains the battery's voltage; a determination unit that determines whether the voltage difference between each obtained voltage is less than threshold value; and a release unit that releases the limits by limiting unit if a determination has been made that the voltage difference is less than threshold value.