Three-Terminal Traction Battery Charging for 400V Charger Compatibility

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Solution Overview

Problem

The incompatibility between existing four-hundred-volt chargers and emerging eight-hundred-volt traction batteries in electric vehicles leads to inefficiencies, as operating the vehicle's inverter in boost mode results in higher losses, reducing charging efficiency.

Innovation Solution

A three-terminal battery system is introduced, allowing charging via a lower voltage charger by coupling it to specific groups of battery cells through high, middle, and low voltage terminals, enabling efficient charging and heating with reduced losses.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a four-hundred-volt charger is used to charge an eight-hundred-volt battery, then compatibility is achieved, but charging efficiency decreases due to higher losses when operating the inverter in boost mode

Engineering Contradiction:

Improvecharger compatibilityVSAvoidcharging losses

Core Design Contradiction:

Adaptability or versatilityVSLoss of energy

Solution Approach 1:

The battery pack is divided into two separate groups of battery cells (first group and second group) that can be independently connected to the charger. This segmentation allows the eight-hundred-volt battery to be charged in two separate half-charging cycles, with each cycle charging one group of cells at a time through the four-hundred-volt charger, thereby avoiding the need for boost mode operation and reducing energy losses.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system dynamically switches between different connection configurations using switching devices (transistors). During charging, the switching devices alternately connect the first group and second group of battery cells to the charger terminals, enabling dynamic reconfiguration of the battery groups to match the charger's voltage output, thus achieving efficient charging without boost mode.

Inventive Principle:

Principle #15Dynamics

2Adaptability or versatility

If the inverter is operated in boost mode to enable four-hundred-volt charger compatibility with eight-hundred-volt batteries, then voltage matching is achieved, but charging efficiency is reduced

Engineering Contradiction:

Improvevoltage compatibilityVSAvoidcharging efficiency

Core Design Contradiction:

Adaptability or versatilityVSProductivity

Solution Approach 1:

Instead of boosting the charger's four-hundred-volt output to eight-hundred-volts through the inverter (traditional approach), the system inverts the approach by directly connecting groups of battery cells to the charger's voltage terminals, allowing the battery groups to be charged at their appropriate voltage levels without requiring voltage boosting, thereby maintaining high charging efficiency.

Inventive Principle:

Principle #13The other way round (Inversion)

3Productivity

If a three-terminal battery system is implemented to enable efficient charging, then charging efficiency is improved, but device complexity increases

Engineering Contradiction:

Improvecharging efficiencyVSAvoidbattery system complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The middle voltage terminal serves multiple functions: it acts as a connection point for the first group of battery cells during their charging cycle, as a connection point for the second group of battery cells during their charging cycle, and provides a reference potential for the switching operations. This multi-functionality reduces the need for additional dedicated terminals or components, thereby limiting the increase in system complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 approach enhances charging efficiency and allows for simultaneous charging of higher voltage batteries using lower voltage chargers, while minimizing energy losses and ensuring even cell charging.

Implementation Method 1

alternating between delivering power from a first charger to a first group of battery cells of a traction battery and from the first charger to a second group of battery cells of the traction battery

Methodology Applied

Scientific EffectElectrical Energy Transformation:

Implementation Method 2

alternating between supplying current and receiving current via the first group of battery cells, and alternating between supplying and receiving current via the second group of battery cells

Methodology Applied

Scientific EffectJoule Heating: Joule Heating

Data Source

PatentUS12508948B2Methods and system for charging and heating a traction battery

Publication Date: 2025.12.30 FORD GLOBAL TECH LLC

AI summary

Systems and methods for operating a vehicle power system are described. The vehicle power system includes an inverter and an electric machine. Switches and a diode are arranged in a way that allows a traction battery to be charged by either a lower voltage charger or a higher voltage charger. Additionally, the switches and diode allow the vehicle power system to heat the traction battery so that the traction battery may operate in a desired temperature range.