DC/DC Converter Topology for Lower Parasitic Loss and Higher Capacitance

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Solution Overview

Problem

Conventional DC/DC converters experience high power loss due to equivalent series resistance from high-voltage and low-voltage side capacitors and suffer from reduced equivalent capacitance at higher DC voltages, limiting their efficiency and performance.

Innovation Solution

The DC/DC converter design reduces power loss by minimizing the number of capacitors AC current flows through, with the high-voltage side capacitor's DC voltage offset decreased, allowing for the use of capacitors with higher equivalent capacitance, and filters voltage ripple using series-connected capacitors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If conventional DC/DC converter uses multiple capacitors in AC current loops, then voltage filtering is achieved, but power loss increases due to parasitic resistance

Engineering Contradiction:

Improvepower lossVSAvoidcapacitor configuration

Core Design Contradiction:

Loss of energyVSDevice complexity

Solution Approach 1:

The patent extracts the high-voltage side capacitor from the AC current loop by reconfiguring the circuit topology. The capacitor is connected in parallel with the input terminals rather than being part of the switching loop, so AC current flows through only the low-voltage side capacitor. This extraction eliminates the parasitic resistance contribution of the high-voltage capacitor from the AC current path, reducing power loss.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent segments the capacitor functions by having the low-voltage side capacitor handle AC current filtering while the high-voltage side capacitor handles DC voltage stabilization. This functional segmentation allows each capacitor to be optimized for its specific role, with the high-voltage capacitor not burdened by AC current path requirements.

Inventive Principle:

Principle #1Segmentation

2Volume of stationary object

If high-voltage side capacitor uses multi-layer ceramic capacitors (MLCC) to meet space limitations, then compact design is achieved, but equivalent capacitance decreases as DC voltage increases

Engineering Contradiction:

Improvecapacitor volumeVSAvoidequivalent capacitance

Core Design Contradiction:

Volume of stationary objectVSReliability

Solution Approach 1:

The low-voltage side capacitor acts as an intermediary that handles the AC current filtering function, allowing the high-voltage side capacitor to focus solely on DC voltage stabilization. This mediator approach enables the high-voltage capacitor to operate in a more favorable electrical environment where its equivalent capacitance is less degraded by voltage effects.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent recognizes that the equivalent capacitance of MLCCs is dynamic and voltage-dependent, decreasing as DC voltage increases. By reconfiguring the circuit so the high-voltage capacitor is not part of the AC current loop, the effective capacitance requirement is reduced, allowing the use of smaller MLCCs that still meet performance requirements despite voltage-dependent capacitance reduction.

Inventive Principle:

Principle #15Dynamics

3Adaptability or versatility

If high-voltage side capacitor handles both AC current filtering and DC voltage stabilization, then single capacitor does dual function, but DC voltage offset increases and equivalent capacitance decreases

Engineering Contradiction:

Improvecapacitor functionVSAvoidequivalent capacitance

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The low-voltage side capacitor serves as a universal component that handles AC current filtering, while the high-voltage side capacitor specializes in DC voltage stabilization. This division of labor allows each capacitor to perform its designated function more effectively, with the high-voltage capacitor's equivalent capacitance less affected by operational stresses.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS11923772B2DC/DC converter for decreasing power loss caused parasitic resistance and increasing equivalent capacitance of high-voltage side capacitor

Publication Date: 2024.03.05 DELTA ELECTRONICS INC(CN)

AI summary

A DC/DC converter includes a high-voltage side, a low-voltage side, a high-voltage side capacitor and a power conversion circuit. The high-voltage side includes a high-voltage positive terminal and a high-voltage negative terminal. The low-voltage side includes a low-voltage positive terminal and a low-voltage negative terminal. The low-voltage negative terminal is electrically connected with the high-voltage negative terminal A first terminal of the high-voltage side capacitor is electrically connected with the high-voltage positive terminal. A second terminal of the high-voltage side capacitor is electrically connected with the low-voltage positive terminal. The power conversion circuit is electrically connected between the high-voltage side and the low-voltage side. The power conversion circuit includes at least one switch and at least one magnetic assembly.