Segmented Thyristor Triggering for Stable Breakdown Voltage
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Solution Overview
Problem
Conventional thyristor triggering methods at high positive voltages suffer from non-stable breakdown voltages, excessive trigger currents, and increased voltage drop, leading to increased dissipation in the on-state, particularly when using negative current triggering.
Innovation Solution
A thyristor design with separate segments for the trigger current and main current path, where the trigger current is provided to one segment without passing through the other, allowing independent impedance control and electrical isolation, using a resistive element to connect the third region to ground and optionally a diode in parallel to limit negative voltage, enabling negative trigger current operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If negative current is used to trigger the thyristor by providing current to the base of the PNP transistor or emitter of the NPN transistor, then triggering capability is achieved, but non-stable breakdown voltages and excessive trigger currents occur
Solution Approach 1:
The fourth region (NPN emitter) is divided into two separate segments: a first segment for main current conduction and a second segment for trigger current injection. This segmentation allows the trigger current to be applied to the second segment without passing through the first segment, enabling independent optimization of triggering characteristics and main current conduction properties, thereby achieving stable breakdown voltage while maintaining triggering capability
2Ease of operation
If negative current triggering is implemented through known methods, then triggering is achieved, but excessive trigger currents are required
Solution Approach 1:
By segmenting the fourth region into separate trigger and main current paths, the trigger current is confined to the second segment and does not need to flow through the entire device structure. This reduces the total trigger current requirement while maintaining effective triggering capability
Solution Approach 2:
The third region (PNP base) acts as an intermediary that receives the negative trigger current from the second segment and converts it into the appropriate base current for the PNP transistor, enabling efficient triggering with reduced current magnitude
3Ease of operation
If conventional negative current triggering is used, then triggering capability is achieved, but increased voltage drop occurs resulting in increased dissipation
Solution Approach 1:
The separation of trigger and main current paths ensures that the high-impedance trigger path does not affect the low-impedance main current path. This independent design minimizes voltage drop during conduction and reduces power dissipation in the on-state while maintaining triggering capability
Data Source
AI summary
A thyristor is disclosed comprising: a first region of a first conductivity type; a second region of a second conductivity type and adjoining the first region; a third region of the first conductivity type and adjoining the second region; a fourth region of the second conductivity type and comprising a first segment and a second segment separate from the first segment, the first segment and second segment each adjoining the third region; a first contact adjoining the first region; a second contact adjoining the first segment; and a trigger contact adjoining the second segment and separate from the second contact.