Split-Battery Charging Circuit for High-Voltage EV Packs

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Solution Overview

Problem

Conventional charging circuits for electric vehicles with high battery voltages face inefficiencies and high costs due to the need for complex voltage conversion and significant electrical losses when charging devices with nominal voltages exceeding standard charging station capabilities.

Innovation Solution

A charging circuit with a DC-DC converter that splits the electrical energy storage into two parts, where one part is charged directly from the charging station and the other part is charged via a DC-DC converter, reducing the need for full voltage conversion and minimizing electrical losses.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If a DC-DC converter is used to convert the charging voltage to match the high nominal voltage of the electrical energy storage device, then the electrical energy storage device can be charged, but significant electrical losses occur and charging efficiency decreases

Engineering Contradiction:

Improveelectrical lossesVSAvoidcharging efficiency

Core Design Contradiction:

Loss of energyVSProductivity

Solution Approach 1:

The electrical energy storage device is divided into two parts: a first part connected directly to the charging station and a second part connected through a DC-DC converter. This segmentation allows only the voltage difference to be converted, reducing electrical losses and improving charging efficiency.

Inventive Principle:

Principle #1Segmentation

2Ease of manufacture

Engineering Contradiction:

Improvecost and size of DC-DC converterVSAvoidcharging capability

Core Design Contradiction:

Ease of manufactureVSProductivity

Solution Approach 1:

By segmenting the electrical energy storage device into two parts, the DC-DC converter only needs to handle a portion of the total charging power. This reduces the size, complexity, and cost of the DC-DC converter while maintaining the ability to charge the entire energy storage device.

Inventive Principle:

Principle #1Segmentation

3Adaptability or versatility

If the charging voltage from the charging station is directly applied to the electrical energy storage device, then charging is simple, but this is not possible when the nominal voltage of the energy storage device exceeds the maximum charging voltage of the charging station

Engineering Contradiction:

Improvecompatibility with charging stationsVSAvoidcomplexity of charging circuit

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The charging circuit is segmented into a direct connection path for the first part of the energy storage device and a converted connection path for the second part. This allows the system to adapt to charging stations with lower maximum voltages while keeping the charging circuit relatively simple.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The DC-DC converter acts as an intermediary component that bridges the voltage mismatch between the charging station and the high-voltage electrical energy storage device, enabling compatibility without requiring complete voltage conversion.

Inventive Principle:

Principle #24Intermediary (Mediator)

4Reliability

If the entire electrical energy storage device is charged through a DC-DC converter, then voltage matching is achieved, but electrical losses increase and the DC-DC converter becomes unnecessarily large

Engineering Contradiction:

Improvevoltage matchingVSAvoidelectrical losses

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The electrical energy storage device is divided into two parts with different charging paths. The first part is charged directly from the charging station, maintaining voltage matching reliability, while the second part is charged through the DC-DC converter. This segmentation minimizes electrical losses and optimizes the size of the DC-DC converter.

Inventive Principle:

Principle #1Segmentation

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 by reducing electrical losses and allowing for a smaller DC-DC converter, while ensuring the electrical energy storage device can be charged effectively with a voltage below its nominal level, thus improving overall efficiency and reducing costs.

Implementation Method 1

The DC-DC converter (14) is designed to convert an electrical voltage provided by the DC voltage source (3) into an other electrical voltage and to charge the second part (22) of the electrical energy storage device (2) with this other electrical voltage.

Methodology Applied

Scientific EffectDC-DC conversion:

Data Source

PatentEP4260427B1Charging circuit and method for charging an electrical energy store, and electric vehicle

Publication Date: 2025.01.08 ROBERT BOSCH GMBH

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AI summary

The present invention relates to charging an electrical energy store, in particular a traction battery of an electric vehicle, wherein the electrical energy store has a rated voltage which is higher than an electrical voltage provided for charging. For this purpose, one portion of the electrical energy store is charged directly by the electrical voltage provided, and a further portion of the electrical energy store is charged by means of an electrical voltage which is converted by a DC-DC converter from the voltage provided for charging. In this way, only some of the energy required for charging the electrical energy store has to be converted by means of a voltage converter.