Dual-Active Bridge OBC Converter for Single- and Three-Phase Charging

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Solution Overview

Problem

Existing AC/DC converters for electric vehicle charging are complex and require separate designs for single-phase and three-phase inputs, leading to increased complexity, maintenance, and potential unwanted oscillations, while also necessitating larger capacitors and inductors for single-phase AC inputs.

Innovation Solution

A single-stage dual-active bridge (DAB) circuit with an auxiliary circuit comprising two or three branches, including switching means and energy storage, allows seamless operation with both single-phase and three-phase inputs by adjusting the auxiliary circuit's operation based on input voltage levels and phases, eliminating the need for additional components and reducing complexity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If separate designs for single-phase and three-phase inputs are used, then compatibility with different input types is achieved, but device complexity increases

Engineering Contradiction:
Improvecompatibility with single-phase and three-phase inputsVSAvoidcircuit complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent implements a universal AC/DC converter design where a single circuit topology can handle both single-phase and three-phase inputs. The converter uses a unified control strategy that automatically adapts to the input phase configuration, eliminating the need for separate dedicated circuits for each input type while maintaining full compatibility.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent employs dynamic switching mechanisms that allow the converter to adapt its operating mode based on the detected input phase configuration. The control system dynamically adjusts switching patterns and parameter settings to optimize performance for either single-phase or three-phase operation, providing versatility without requiring fixed separate designs.

Inventive Principle:
Principle #15Dynamics

2Productivity

If larger capacitors and inductors are used for single-phase AC inputs, then charging performance is improved, but device complexity and maintenance needs increase

Engineering Contradiction:
Improvecharging performanceVSAvoidcomponent size and quantity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent utilizes parameter adjustment techniques where the converter optimizes operating parameters such as switching frequency, duty cycle, and control gains based on the input phase configuration. This allows the same physical components to achieve optimal charging performance in both single-phase and three-phase modes without requiring larger capacitors and inductors specifically for single-phase operation.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent implements periodic switching patterns that are adapted to the input frequency and phase configuration. By using optimized periodic switching sequences, the converter achieves efficient power transfer and charging performance in single-phase mode without requiring oversized energy storage components, thereby reducing overall device complexity.

Inventive Principle:
Principle #19Periodic action

3Loss of time

If high-power OBC is used to reduce charging time, then charging speed is improved, but compatibility with single-phase input becomes more difficult

Engineering Contradiction:
Improvecharging timeVSAvoidcompatibility with single-phase input
Core Design Contradiction:
Loss of timeVSAdaptability or versatility

Solution Approach 1:

The patent employs dynamic control strategies that enable the high-power OBC to adapt its operating characteristics based on the input phase configuration. The control system dynamically adjusts switching patterns, modulation indices, and power management parameters to maintain high charging power levels in both single-phase and three-phase modes, ensuring fast charging capability regardless of input type.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent designs a universal control architecture that provides high-power charging capability across both single-phase and three-phase inputs. The unified control system automatically detects and adapts to the input configuration, delivering optimized high-power performance in either mode without sacrificing compatibility or charging speed.

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

The solution provides a cost-effective, high-power density AC/DC converter with reduced maintenance needs, capable of bi-directional power flow, and efficient charging even in single-phase environments, while minimizing unwanted artifacts and charging time.

Implementation Method 1

an auxiliary circuit with two or three branches, comprising two switching means and energy storage means

Methodology Applied
Scientific EffectCapacitance: Capacitance

Implementation Method 2

The switching means are configured to switch the circuit connections of the energy storage means to the inputs

Methodology Applied
Scientific EffectElectrical switching:

Data Source

PatentEP4308409B1Ac/DC converter and a control method thereof for charging electrical vehicles
Publication Date: 2025.09.24 HUAWEI TECH CO LTD
  • EP4308409B1 patent drawingFigure 1
  • EP4308409B1 patent drawingFigure 2
  • EP4308409B1 patent drawingFigure 3

AI summary

The present disclosure refers to an AC/DC converter for an OBC. The AC/DC converter comprises: a three-phase-input comprising three inputs (a, b, c); a single-stage dual-active bridge, DAB, circuit; and an auxiliary circuit. The auxiliary circuit comprises two switching means (R1, R2) and energy storage means (C1), wherein the auxiliary circuit comprises at least two branches, wherein two branches each comprise one of the switching means (R1, R2), wherein at least one branch is connected to an input (a, b) which is a single-phase AC input, wherein another branch is connected to an input (c) which is not a single-phase AC input, and wherein the other branch comprises the energy storage means (C1).