Transformerless DC-DC Converter for Vehicle Power Supply

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Solution Overview

Problem

Conventional power supply devices for vehicles are expensive due to the use of transformers for DC-DC conversion and fail to provide enhanced safety against ground-side and positive-side faults without adequate cost minimization.

Innovation Solution

A power supply device utilizing a series circuit with capacitors and inductors for DC-wisely isolating the input and output sides, eliminating the need for transformers, and incorporating a control circuit to manage the switching element's on/off operations based on detected faults, ensuring safety and minimizing costs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a transformer is used in the DC-DC conversion circuit, then circuit protection against ground-side and positive-side faults can be achieved, but the device cost increases

Engineering Contradiction:

Improvecircuit protectionVSAvoiddevice cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent extracts and eliminates the transformer from the DC-DC conversion circuit, replacing it with a switching circuit comprising switching elements, capacitors, and inductors. This extraction removes the costly component while maintaining the essential isolation function through alternative circuit topology, thereby reducing device cost while preserving fault protection capability

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces the expensive transformer with cheaper discrete components (switching elements, capacitors, inductors) that can be more economically sourced and assembled. These alternative components achieve the same isolation and protection function at lower cost, making the overall device more affordable without sacrificing reliability

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

2Reliability

If a transformer is used for DC-DC conversion, then safety isolation between input and output can be provided, but the device complexity and cost increase

Engineering Contradiction:

Improvesafety isolationVSAvoidcircuit complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent segments the isolation function into multiple discrete components (switching elements, capacitors, inductors) arranged in a switching circuit topology. This segmentation replaces the monolithic transformer with distributed components that collectively provide the same isolation effect, allowing for modular design and simplified manufacturing while maintaining safety isolation

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent substitutes the magnetic field-based isolation mechanism of the transformer with an electric field-based switching circuit mechanism. By using capacitors and switching elements instead of magnetic cores and windings, the circuit achieves isolation through voltage switching and capacitive coupling, eliminating the need for bulky magnetic components and reducing overall circuit complexity

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 enhanced safety and cost-effectiveness by preventing faults through DC-wise isolation and smart control of the switching element, maintaining power supply to the load while reducing the risk of faults and eliminating the need for transformers.

Implementation Method 1

series circuit including a first capacitor and a first and a second inductor respectively connected to both terminals of the first capacitor

Methodology Applied

Scientific EffectDC-wise isolation: Capacitance

Implementation Method 2

switching element, one terminal of which is connected to a connection node between one terminal of the first inductor and the first capacitor

Methodology Applied

Scientific EffectSwitching operation:

Implementation Method 3

rectifier whose anode is connected to a connection node between the first capacitor and one terminal of the second inductor

Methodology Applied

Scientific EffectRectification: Diode

Data Source

PatentEP2528419B1Power supply device for a lamp and vehicle including the same

Publication Date: 2018.11.28 PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO LTD

Figure 1A~1B
Figure 2A~2B
Figure 3(a)~3(g)

AI summary

A power supply device includes a series circuit including a first capacitor and a first and second inductors connected to both terminals of the first capacitor; a switching element having one terminal connected to a node between one terminal of the first inductor and the first capacitor; a rectifier having an anode connected to a node between the first capacitor and one terminal of the second inductor; and a second capacitor connected between the other terminal of the switching element and a cathode of the rectifier. Further, a DC power supply source is connected between the other terminal of the first inductor and the other terminal of the switching element such that the other terminal of the first inductor is connected to a positive electrode side of the DC power supply source. A load is connected between the other terminal of the second inductor and the cathode of the rectifier.