Triac-Diode Thyristor Gate Control for Low-Leakage Triggering

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Solution Overview

Problem

Existing control devices for cathode-gate thyristors face inefficiencies in triggering the thyristor to the conducting state in its first quadrant, leading to high leakage currents and the need for complex power supply configurations.

Innovation Solution

A control device comprising a triac and a diode connected in series with the thyristor, allowing for controlled switching in the first quadrant using a single control signal and a positive supply potential, eliminating the need for isolated power sources.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a known control device is used for cathode-gate thyristor, then the thyristor can be controlled, but high leakage currents occur and complex power supply configurations are needed

Engineering Contradiction:
Improvethyristor control reliabilityVSAvoidpower supply configuration complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines the control signal generation and power supply functions into a single integrated control device. The device generates both the control signal and the necessary power supply internally, eliminating the need for separate isolated power sources and reducing overall system complexity while maintaining reliable thyristor control

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The control device is designed to perform multiple functions: it generates control signals, provides power supply, and controls the thyristor switching. This multi-functional integration reduces the number of separate components needed and simplifies the power supply configuration while ensuring reliable operation

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Reliability

If a known control device is used for cathode-gate thyristor, then the thyristor can be controlled, but high leakage currents occur

Engineering Contradiction:
Improvethyristor control reliabilityVSAvoidleakage current
Core Design Contradiction:
ReliabilityVSLoss of energy

Solution Approach 1:

The control device applies preliminary action by generating precise control signals that ensure the thyristor switches exactly when intended. The device monitors and controls the gate current in advance, preventing unwanted leakage currents by maintaining proper bias conditions and ensuring clean transitions between conducting and blocking states

Inventive Principle:
Principle #10Preliminary action

3Use of energy by moving object

If first-quadrant triggering is implemented, then energy efficiency is improved, but complex control devices are required

Engineering Contradiction:
Improvethyristor power consumptionVSAvoidcontrol device complexity
Core Design Contradiction:
Use of energy by moving objectVSDevice complexity

Solution Approach 1:

The patent merges the control signal generation and power supply functions into a single integrated control device. The device generates both the control signal and the necessary power supply internally, eliminating the need for separate isolated power sources and reducing overall system complexity while maintaining reliable thyristor control

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The control device is self-sufficient by generating its own control signals and power supply internally. It does not require external isolated power sources, making the system simpler and more energy-efficient while enabling first-quadrant triggering operation

Inventive Principle:
Principle #25Self-service

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 reduces leakage currents by up to 10-100 times and enables efficient, integrated control of thyristors without requiring complex power supply configurations, suitable for microcontroller implementation.

Implementation Method 1

the thyristor is switched to the conducting state by supplying a positive current to its gate

Methodology Applied
Scientific EffectThyristor triggering:

Implementation Method 2

a first diode connected in series with the triac between the first and second terminals of the device

Methodology Applied
Scientific EffectRectification: Diode

Data Source

PatentEP3965299B1Device for controlling a thyristor
Publication Date: 2026.03.25 STMICROELECTRONICS (TOURS) SAS
  • EP3965299B1 patent drawingFigure 1~2
  • EP3965299B1 patent drawingFigure 3

AI summary

The present description relates to a control device (2) comprising a triac (Tr) and a first diode (D3) connected in series between a first terminal (204) of the device (2) configured to be connected to a cathode gate of a thyristor (Th1), and a second terminal (202) of the device (2) configured to be connected to an anode of the thyristor (Th1), the triac (Tr) having a gate connected to a third terminal (206) of the device (2) configured to receive a control signal.