RC Snubber Circuit for Power Conversion Surge Suppression

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Solution Overview

Problem

Conventional power conversion devices require multiple surge voltage suppression circuits with expensive Zener diodes, leading to high manufacturing costs and increased wiring inductance, which results in inefficiencies when switching semiconductor elements.

Innovation Solution

A power conversion device incorporating a snubber circuit with a resistor and capacitor connected between the negative potential side of the power conversion circuit and the control circuit to suppress surge voltage, reducing the influence of surge voltage on control and low-potential-side terminals.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If dual Zener diode surge voltage suppression circuits are used, then surge voltage suppression is achieved, but manufacturing cost increases and device complexity increases

Engineering Contradiction:

Improvesurge voltage suppressionVSAvoidcircuit configuration

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines the surge voltage suppression function with the existing negative potential side wiring structure by connecting the RC snubber circuit between the negative potential side of the power conversion circuit and the negative potential side of the control circuit. This merging approach eliminates the need for separate dual Zener diode circuits, reducing component count while maintaining surge suppression functionality.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent replaces expensive Zener diodes with a cost-effective RC snubber circuit consisting of a resistor and capacitor. This substitution uses cheaper components to achieve the same surge voltage suppression function, significantly reducing manufacturing costs while maintaining reliability.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

2Reliability

If dual Zener diode surge voltage suppression circuits are used, then surge voltage suppression is achieved, but manufacturing cost increases

Engineering Contradiction:

Improvesurge voltage suppressionVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Reliability

If multiple surge voltage suppression circuits are added, then surge voltage suppression is improved, but wiring inductance increases

Engineering Contradiction:

Improvesurge voltage suppressionVSAvoidwiring inductance

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent extracts the surge voltage suppression function from the traditional dual Zener diode circuit configuration and implements it through a simplified RC snubber circuit connected to the negative potential side. This extraction eliminates unnecessary components and wiring, reducing wiring inductance while maintaining effective surge suppression.

Inventive Principle:

Principle #2Taking out (Extraction)

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 RC snubber circuit effectively suppresses surge voltage between control and low-potential-side terminals, achieving a simpler configuration and larger surge voltage suppression effect compared to traditional dual Zener diode configurations, thereby reducing manufacturing costs and improving operational efficiency.

Implementation Method 1

a snubber circuit including a resistor and a capacitor that are connected between a negative potential side of the power conversion circuit and a negative potential side of the control circuit and are configured to suppress a surge voltage

Methodology Applied

Scientific EffectEnergy absorption: Capacitance

Implementation Method 2

when, for example, an IGBT, as a semiconductor switching element used for a brake circuit and an inverter circuit, is brought from an on-state to an off-state, an overvoltage (surge voltage) generated from stored energy stored in wiring inductance is supplied to between the gate, serving as a control terminal, and the emitter, serving as a low-potential-side terminal, of the IGBT

Methodology Applied

Scientific EffectEnergy dissipation: Joule Heating

Data Source

PatentUS10305372B2Power conversion device with snubber circuit to suppress surge voltage

Publication Date: 2019.05.28 FUJI ELECTRIC CO LTD

AI summary

A power conversion device including: a power conversion circuit including a voltage control type first semiconductor switching element configured to convert DC power to polyphase AC power; a brake circuit including a voltage control type second semiconductor switching element configured to protect the power conversion circuit from an overvoltage applied to the power conversion circuit; a control circuit configured to control the first semiconductor switching element in the power conversion circuit and the second semiconductor switching element in the brake circuit; and a snubber circuit including a resistor and a capacitor that are connected between a negative potential side of the power conversion circuit and a negative potential side of the control circuit and are configured to suppress a surge voltage.