Multi-Voltage EV Charging Circuit for 400V/800V Battery Reconfiguration
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Solution Overview
Problem
Electrified vehicles face challenges in efficiently charging larger traction battery packs due to practical limitations in current charging systems, which struggle to provide sufficient power without modifying existing electric powertrain hardware.
Innovation Solution
A multi-voltage charging circuit that configures power delivery to traction battery packs at different voltage levels (e.g., 400V and 800V) by controlling contactors and using a DC/DC converter to step down voltage, allowing for parallel and series configurations of battery arrays based on the charger coupler type plugged into the vehicle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a single voltage level charging system is used, then the hardware configuration is simple, but the charging power and efficiency are limited
Solution Approach 1:
The charging system dynamically reconfigures the battery array connections between series and parallel configurations based on the detected charger voltage level. When an 800V charger is detected, the system switches to series configuration to accept higher voltage charging; when a 400V charger is detected, it switches to parallel configuration. This dynamic adaptability enables the system to achieve higher charging power with 800V chargers while maintaining compatibility with 400V chargers, resolving the contradiction between charging power and device complexity.
Solution Approach 2:
The system changes the electrical parameters (voltage and current distribution) by reconfiguring the battery array connections. By switching between series and parallel configurations, the system adapts its voltage acceptance capability to match the charger's output voltage level. This parameter change strategy allows the charging system to optimize power transfer efficiency and charging speed across different voltage conditions without requiring separate charging circuits for each voltage level.
2Productivity
If battery arrays are connected in series for high voltage charging, then charging efficiency increases, but the system cannot support auxiliary loads requiring lower voltage
Solution Approach 1:
The battery pack is segmented into multiple battery arrays that can be independently connected in series or parallel configurations. This segmentation allows the system to create different voltage levels by selectively connecting the arrays. When series connection is needed for high-voltage charging, the arrays are connected end-to-end; when parallel connection is needed for auxiliary power, the arrays are connected at both terminals. This modular segmentation enables the system to achieve both high charging efficiency and voltage adaptability for auxiliary loads.
Solution Approach 2:
The system dynamically reconfigures the battery array connections based on the operating mode detected. During DC fast charging at 800V, the arrays are connected in series to maximize charging efficiency. During normal operation requiring auxiliary power, the arrays are reconfigured to parallel connection to provide stable lower voltage. This dynamic switching capability, controlled by contactors and monitored by the control system, resolves the contradiction between charging efficiency and voltage adaptability.
3Ease of manufacture
If the charging system is designed for a specific voltage level, then the system design is straightforward, but the system cannot accommodate different charger types
Solution Approach 1:
The charging system is designed with multi-functionality to accommodate both 400V and 800V charger types using the same hardware infrastructure. The battery pack includes battery arrays with terminals configured to support both voltage levels through different connection topologies. The control system detects the charger type and automatically reconfigures the battery arrays accordingly, enabling a single charging system design to serve multiple voltage requirements without requiring separate dedicated circuits for each charger type.
Solution Approach 2:
The control system acts as an intermediary that manages the transition between different charging configurations. It detects the charger type plugged into the charge port and coordinates the switching of contactors to achieve the appropriate battery array configuration. This intermediary control layer simplifies the overall system design by providing a unified interface that handles both 400V and 800V charging scenarios, eliminating the need for complex dual-purpose circuit designs and making the system adaptable to different charger 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
Enables higher power charging without modifying existing hardware, supporting auxiliary loads and optimizing charging efficiency across various voltage conditions.
Implementation Method 1
a DC/DC converter configured to step down the second voltage level to the first voltage level for supporting auxiliary loads during the second charging condition
Data Source
AI summary
This disclosure describes charging systems for electrified vehicles. Exemplary charging systems may employ a multi-voltage charging circuit that supports charging of a traction battery pack at both a first voltage level during a first charging condition and a second, different voltage level during a second charging condition. Higher voltage levels may be experienced during the second charging condition as compared to the first charging condition.