Dual EV Battery Charge Balancing Before 400V or 800V Charging

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Solution Overview

Problem

Dual battery systems in electric vehicles face challenges in balancing charge levels, which affects charging capabilities and efficiency, especially when switching between different charging voltages.

Innovation Solution

A method where the dual battery system balances charge levels during vehicle operation by selecting an adapted driving scenario based on upcoming charging events, allowing direct charging initiation without additional preparation, using a switch arrangement to connect batteries in parallel, series, or disconnect them as needed.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If increased battery capacity is implemented to improve electric vehicle performance, then the battery capacity is improved, but the charging time increases

Engineering Contradiction:
Improvebattery capacityVSAvoidcharging time
Core Design Contradiction:
Quantity of substanceVSLoss of time

Solution Approach 1:

The battery system is divided into two separate batteries (first battery and second battery) that can operate independently or together. This segmentation allows the system to manage charge distribution more effectively, enabling faster charging by charging both batteries simultaneously in parallel mode, thus reducing overall charging time while maintaining high capacity.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The system performs preliminary balancing of charge levels between the two batteries before charging events. By monitoring and adjusting charge levels in advance, the system ensures both batteries are optimally prepared for charging, maximizing charging speed and capacity utilization when charging occurs.

Inventive Principle:
Principle #10Preliminary action

2Adaptability or versatility

If dual battery system switches between parallel and series connection to enable different charging voltages, then the adaptability to charging voltages is improved, but the charging capability deteriorates due to unbalanced charge levels

Engineering Contradiction:
Improvecharging voltage adaptabilityVSAvoidcharging capability
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The system continuously monitors the charge levels of both batteries and uses this feedback to determine the optimal connection configuration (parallel or series) and to trigger balancing operations when needed. This feedback mechanism ensures the system maintains balanced charge levels across different charging voltage modes, preserving charging capability while adapting to different voltage requirements.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The switch arrangement dynamically changes the connection topology between batteries based on real-time operating conditions, charge levels, and charging requirements. The system can transition between parallel connection (for 400V charging with balanced batteries) and series connection (for 800V charging), optimizing performance for each scenario while maintaining reliability through active charge level management.

Inventive Principle:
Principle #15Dynamics

3Ease of operation

If charging is initiated without battery balancing, then the charging process is simplified, but the charging efficiency deteriorates due to unbalanced batteries

Engineering Contradiction:
Improvecharging initiation simplicityVSAvoidcharging efficiency
Core Design Contradiction:
Ease of operationVSProductivity

Solution Approach 1:

The system performs preliminary balancing of charge levels between the two batteries before charging events. By monitoring and adjusting charge levels in advance, the system ensures both batteries are optimally prepared for charging, maximizing charging speed and capacity utilization when charging occurs.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system automatically manages battery balancing through the control unit, which monitors charge levels and activates balancing protocols when needed without requiring manual intervention. This self-service approach maintains charging efficiency while keeping the charging process simple for the user, as the system handles the complexity of battery management autonomously.

Inventive Principle:
Principle #25Self-service

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 direct charging upon arrival at a charging station, utilizing full charging capabilities and maintaining balanced batteries for efficient charging at either 400 V or 800 V, thereby optimizing battery performance and charging speed.

Implementation Method 1

two batteries which are electrically connectable in parallel or in series, by means of a switch arrangement. This enables the electric vehicle battery system to operate and/or charge at a first voltage, e.g. 400 V, and to operate and/or charge at a second voltage, higher than the first voltage, e.g. 800 V.

Methodology Applied
Scientific EffectElectrical connection in parallel or series: Conduction (electrical)

Implementation Method 2

charging capabilities greatly benefit from the two batteries being balanced in terms of charge level. This has the positive effect that charging may be initiated directly when arriving at a charging stop, without any further actions necessary in order to prepare the dual battery system for charging.

Methodology Applied
Scientific EffectCharge level balancing:

Data Source

PatentEP3862218B1Balancing charge level of batteries
Publication Date: 2023.11.29 POLESTAR PERFORMANCE
  • EP3862218B1 patent drawingFigure 1
  • EP3862218B1 patent drawingFigure 2
  • EP3862218B1 patent drawingFigure 3

AI summary

The present disclosure relates to a dual battery system (1) comprising a first battery (B1) and a second battery (B2), for balancing charge level of the first battery and the second battery, the dual battery system being adapted for powering propulsion of an electric vehicle (3) comprising a first electric motor (El) coupled in driving relationship with one or more rear wheels of the electric vehicle and a second electric motor (E2) coupled in driving relationship with one or more front wheels of the electric vehicle. The first battery is adapted to provide electric power for driving the first electric motor and the second battery is adapted to provide electric power for driving the second electric motor. The dual battery system obtains (100) at least one of data or information of a predetermined and/or imminent charging event of the electric vehicle. The dual battery system furthermore obtains (200) at least one of data or information of charge level of the first battery and second battery respectively. Moreover the dual battery system selects (300), when the charge level of the first battery and the second battery are unbalanced, a driving scenario which comprises charging and/or discharging of at least one of the first battery and the second battery, the driving scenario balancing the charge level of the first battery and the second battery prior to arriving at the predetermined and/or imminent charging event. The disclosure also relates to a dual battery system in accordance with the foregoing, and an electric vehicle comprising such a dual battery system.