Dual DC-DC EV Charger for Wide-Voltage V2V Charging
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Solution Overview
Problem
There is a need for high efficiency electric vehicle (EV) chargers that can handle a wide range of input/output voltages and provide vehicle-to-vehicle (V2V) charging capability, especially in scenarios where grid power is not available.
Innovation Solution
The charger is configured with a variable transformer to partition the output voltage range into multiple subranges, and the switching frequency of the DC-DC converter can be doubled to reduce peak current. It also features two outputs for multiple charging modes, including V2V charging, which allows power transfer between electric vehicles without relying on grid connection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the charger uses a single DC-DC converter for charging, then the device complexity is reduced, but the charging power and productivity are limited
Solution Approach 1:
The patent combines two DC-DC converters into a single charger system, merging their outputs to provide higher charging power. The controller coordinates both converters to work simultaneously or in complementary modes, achieving increased productivity while maintaining manageable complexity through integrated control.
Solution Approach 2:
The charger with two DC-DC converters is designed to perform multiple functions: it can charge a single vehicle at high power using both converters, charge two vehicles simultaneously using each converter separately, or enable V2V charging by allowing power transfer between connected vehicles. This multi-functionality increases productivity across various operating scenarios.
2Adaptability or versatility
If the charger includes AC-DC converter stage, then it can accept grid power input, but the efficiency is reduced due to additional conversion losses
Solution Approach 1:
The patent extracts or removes the AC-DC converter stage from the charging path when grid power is not needed. By enabling direct DC-DC conversion between vehicles, the system eliminates the unnecessary AC-DC conversion step, reducing energy losses while maintaining the capability to accept grid power when required.
Solution Approach 2:
The charger dynamically adapts its conversion path based on operating conditions. When grid power is available, it uses the AC-DC converter stage; when performing V2V charging, it bypasses the AC-DC stage and uses only DC-DC conversion. This dynamic configuration optimizes efficiency while maintaining versatility.
3Productivity
If the charger is designed for high charging current to meet power requirements, then the productivity is improved, but the charger overheating and reliability worsen
Solution Approach 1:
The patent segments the high current charging function into two separate DC-DC converters working in parallel. Each converter handles a portion of the total charging current, reducing the current burden on individual components. This segmentation distributes thermal load, improving reliability while maintaining high overall charging power capability.
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 charger achieves high efficiency, up to 98%, by bypassing the AC-DC converter stage and using only two DC-DC converters for V2V charging, enabling effective charging in various scenarios, including remote areas and during power outages.
Implementation Method 1
the charger can include a variable transformer to partition the output voltage range into multiple subranges
Implementation Method 2
power from an electric vehicle is converted by a DC-DC converter to a common voltage, such as at the DC link capacitor
Data Source
AI summary
An EV charger has an AC-DC converter coupled to two DC-DC converters can be configured with V2V charging capability, together with a wide range of input/output voltages for accepting existing electric vehicle available on the market. The charger can include a variable transformer to partition the output voltage range into multiple subranges. In addition, the switching frequency of the DC-DC converter can be doubled when the voltage gain of the DC-DC converter deviates significantly from unity.