Bidirectional DC/DC Converter Voltage Stabilization

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Solution Overview

Problem

Existing vehicle electrical systems face challenges in stabilizing voltage fluctuations during load changes, particularly due to overvoltages and undervoltages, which existing technologies are unable to effectively compensate for.

Innovation Solution

A vehicle electrical system with a first and second branch, each with a nominal voltage, and a bidirectional DC/DC converter controlled by a control unit that transfers energy between the branches based on voltage threshold comparisons to maintain stable voltage levels, using a voltage limiting switch for additional stabilization.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a DC/DC converter is used to transfer energy between voltage branches, then voltage stabilization is improved, but device complexity increases

Engineering Contradiction:
Improvevoltage stabilizationVSAvoiddevice complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent introduces a DC/DC converter as an intermediary device between two voltage branches (first branch with nominal voltage U1 and second branch with nominal voltage U2). This converter acts as a mediator to transfer energy bidirectionally, stabilizing voltage fluctuations in one branch by compensating with energy from or to the other branch, thereby improving voltage reliability while managing system complexity through controlled energy transfer.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If energy transfer control based on voltage threshold comparison is implemented, then voltage stability is improved, but control complexity increases

Engineering Contradiction:
Improvevoltage stabilityVSAvoidcontrol complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent implements a feedback control mechanism where a determination unit continuously monitors the instantaneous voltage Uist,1 in the first branch and compares it with predetermined threshold values (Uo,1 and Uu,1). Based on this feedback comparison, the control unit automatically adjusts the DC/DC converter's energy transfer operation to maintain voltage within acceptable ranges, improving voltage stability through closed-loop control.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The control system changes operational parameters (energy transfer direction and magnitude) based on voltage threshold comparisons. When Uist,1 exceeds Uo,1, energy transfers from first to second branch; when Uist,1 falls below Uu,1, energy transfers from second to first branch. This parameter-based control strategy simplifies the control logic while maintaining voltage stability.

Inventive Principle:
Principle #35Parameter changes

3Adaptability or versatility

If bidirectional energy transfer is enabled between voltage branches, then compensation capability is improved, but device complexity increases

Engineering Contradiction:
Improvecompensation capabilityVSAvoiddevice complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The DC/DC converter is designed with bidirectional energy transfer capability, making it a universal device that can operate in multiple modes: transferring energy from first branch to second branch when overvoltage occurs, transferring energy from second branch to first branch when undervoltage occurs, and potentially operating in different conversion modes (step-up, step-down) depending on voltage levels. This multi-functionality improves compensation capability while consolidating control logic.

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 solution effectively reduces or compensates for voltage fluctuations by transferring energy between branches, maintaining the nominal voltage and stabilizing the electrical system, especially during load changes, thereby enhancing voltage stability and reducing the need for larger power classes in generators and energy storage devices.

Implementation Method 1

at least one DC/DC converter, which is designed to transmit energy at least between the first vehicle electrical system branch and the second vehicle electrical system branch

Methodology Applied
Scientific EffectElectrical energy conversion: Electromagnetic Induction

Data Source

PatentEP2783442B1Vehicle electrical system and method for operating a vehicle electrical system
Publication Date: 2018.10.24 CONTINENTAL AUTOMOTIVE GMBH
  • EP2783442B1 patent drawingFigure 1A~1B
  • EP2783442B1 patent drawingFigure 2~3

AI summary

One subject matter of the application relates to a vehicle electrical system (8), which has a first vehicle electrical system branch (1) with a first nominal voltage U1 and a second vehicle electrical system branch (2) with a second nominal voltage U2. The vehicle electrical system (8) further comprises at least one DC/DC converter (3), which is designed to transmit energy between the first vehicle electrical system branch (1) and the second vehicle electrical system branch (2). The vehicle electrical system (8) further comprises a first actuating unit (4), designed to actuate the at least one DC/DC converter (3), and a first detection unit (5), designed to detect a instantaneous voltage Uist, 1 of the first vehicle electrical system branch (1). The vehicle electrical system (8) further comprises a comparison unit (6), which is designed to compare the detected instantaneous voltage Uist, 1 to a first upper voltage threshold value Uo, 1 and to a first lower voltage threshold value Uu, 1, wherein Uu, 1 < U1 < Uo, 1. The first actuating unit (4) is designed to actuate the at least one DC/DC converter (3) in such a manner that energy is transmitted from the first vehicle electrical system branch (1) to the second vehicle electrical system branch (2) if Uist, 1 > Uo, 1, and in such a manner that energy is transmitted from the second vehicle electrical system branch (2) to the first vehicle electrical system branch (1) if Uist, 1 < Uu, 1.