EV Charging Voltage Negotiation for 400 V/800 V Battery Switching
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Solution Overview
Problem
Existing electric vehicle charging systems, particularly those adhering to the GB/T standard, face inefficiencies and limitations when trying to charge vehicles at higher voltage levels like 800 V, as they are designed for a fixed voltage of 400 V, leading to reduced performance and potential errors during voltage switching.
Innovation Solution
A method where the battery management system communicates a reduced maximum permissible total charging voltage to the charging station through a battery handshake message, allowing for safe and reliable switching between voltage levels, optimizing the charging process by negotiating the charging voltage within the constraints of the charging station's capabilities and insulation tests.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the charging column operates at a fixed voltage level of 400 V according to GB/T standards, then compliance with charging standards is ensured, but the ability to charge vehicles at higher voltage levels (800 V) is lost
Solution Approach 1:
The charging column dynamically switches between 400 V and 800 V operating modes based on the vehicle's requirements. The system transitions from a static fixed-voltage design to a dynamic multi-voltage system, enabling adaptability while maintaining standard compliance through controlled state changes
Solution Approach 2:
The charging column changes its operating voltage parameter from a fixed 400 V to a variable parameter that can be 400 V or 800 V. This parameter change enables the system to adapt to different vehicle voltage levels while maintaining reliability through standardized communication protocols
2Productivity
If the charging column switches voltage levels during the charging process, then charging efficiency for 800 V vehicles is improved, but error modes occur due to standard limitations
Solution Approach 1:
The charging column performs preliminary actions by negotiating the voltage level with the vehicle's battery management system before starting the charging process. This preliminary voltage negotiation prevents errors during charging by ensuring both parties agree on the operating voltage, thereby improving productivity while maintaining reliability
Solution Approach 2:
The system implements feedback through communication between the charging column and the vehicle's battery management system. The battery management system provides feedback about the vehicle's voltage requirements, and the charging column adjusts its operation accordingly, ensuring stable and efficient charging without triggering error modes
3Power
If the maximum permissible total charging voltage is communicated accurately, then charging power is maximized, but error messages arise when vehicle voltage exceeds standard limits
Solution Approach 1:
The system changes the communicated maximum permissible total charging voltage parameter based on the vehicle's actual voltage level. For 800 V vehicles, the system communicates an appropriate voltage value that reflects the vehicle's capabilities rather than the standard 400 V limit, thereby maximizing charging power while avoiding error messages through adaptive parameter communication
Data Source
AI summary
A method for charging a traction battery (1) of an electric vehicle b a charging column (2) is provided. The traction battery (1) can be charged at two or more different charging voltage levels. After the electric vehicle has been connected to the charging column (2), data is exchanged between a battery management system (3) of the electric vehicle and the charging column (2) to negotiate a charging voltage. For this purpose, a maximum permissible total charging voltage is communicated to the charging station (2) by the battery management system (3) via a battery handshake message (BHM) (4). The communicated maximum permissible total charging voltage is lower than a highest charging voltage level of the traction battery (1) by a defined measure.