DC Electronic Switch With Suppressor Diodes for Overvoltage Clamping

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Solution Overview

Problem

Existing electronic switches in DC networks face challenges with continued current flow after shutdown due to line and load inductances, leading to high voltage across the switch and potential damage.

Innovation Solution

The electronic switch incorporates a bidirectional, turn-off semiconductor switching element and a voltage limiting circuit with multiple bidirectional suppressor diodes, eliminating the need for large capacitors and allowing for efficient voltage limitation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a capacitor is installed parallel to the semiconductor switches to slow voltage rise, then the voltage dissipation becomes unproblematic, but the capacitor is large and heavy, significantly increasing the overall size of the electronic switch

Engineering Contradiction:

Improvevoltage dissipation capabilityVSAvoidsize of electronic switch

Core Design Contradiction:

ReliabilityVSWeight of stationary object

Solution Approach 1:

The patent changes the fundamental parameter of voltage limitation from capacitive energy storage to suppressor diode breakdown voltage characteristics. By using suppressor diodes with specific breakdown voltages (e.g., 600V, 800V, 1000V) arranged in series, the solution achieves voltage limitation without requiring large capacitive components, thus reducing size and weight while maintaining reliability

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces the mechanical/electrical energy storage system (capacitor) with a semiconductor-based voltage clamping system (suppressor diodes). The suppressor diodes utilize their inherent breakdown characteristics to limit voltage, substituting the need for large physical capacitors and reducing the overall device footprint

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Weight of stationary object

If suppressor diodes are used for voltage limitation, then the size and weight are significantly reduced, but power loss occurs in the suppressor diode during the non-destructive breakdown process

Engineering Contradiction:

Improvesize of electronic switchVSAvoidpower loss in suppressor diode

Core Design Contradiction:

Weight of stationary objectVSLoss of energy

Solution Approach 1:

The patent accepts partial energy dissipation in the suppressor diodes as an acceptable trade-off for the dramatic reduction in component size. The suppressor diodes are designed to handle the peak power during fault conditions (tens of kW for approximately 200 μs), and their smaller physical footprint provides a net system-level benefit despite the localized power loss

Inventive Principle:

Principle #16Partial or excessive action

Solution Approach 2:

The patent converts the potentially harmful high voltage spike into a controlled breakdown event in the suppressor diodes. The non-destructive breakdown process, which initially appears as energy loss, actually serves the beneficial function of clamping the voltage to safe levels and protecting the semiconductor switches from damage

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Speed

If semiconductor switches are used to interrupt fault current rapidly, then the interruption speed is improved, but high voltage builds up across the switch due to line inductances, potentially damaging the semiconductor

Engineering Contradiction:

Improvefault current interruption speedVSAvoidvoltage spike damage risk

Core Design Contradiction:

SpeedVSObject-affected harmful factors

Solution Approach 1:

The patent introduces suppressor diodes as intermediary components between the semiconductor switches and the high voltage spikes. When voltage exceeds the suppressor diode breakdown voltage, the diodes conduct and provide a parallel path for the inductive current, thereby clamping the voltage across the semiconductor switches to safe levels

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The suppressor diodes are pre-configured in parallel with the semiconductor switches to provide protective cushioning before damage can occur. The breakdown voltage of the suppressor diodes is selected to be below the maximum voltage the semiconductor switches can withstand, providing a safety margin that protects the switches during rapid fault current interruption

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

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 configuration reduces the size and weight of the electronic switch, effectively limits voltage spikes, and allows for rapid fault current interruption, even in high-voltage DC networks.

Implementation Method 1

suppressor diodes advantageously enable the limitation of a build-up of voltage across the semiconductor switch. Since this limitation occurs via a non-destructive breakdown of the suppressor diodes

Methodology Applied

Scientific EffectBreakdown voltage: Avalanche Breakdown

Data Source

PatentEP4064563B1Electronic switch

Publication Date: 2025.06.18 SIEMENS AG

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AI summary

A semiconductor-based switch, especially for DC networks, has one or more bidirectional suppressor diodes connected in series in parallel with the semiconductor switches in the current path for overvoltage limitation.