Three-terminal power device switching speed via Zener diode
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Solution Overview
Problem
Existing three-terminal power devices, such as those based on thyristors and MOSFETs, face challenges with high power dissipation, modest reverse-bias safe-operating area (RBSOA), and long turn-off times, while also deviating from the standard three-terminal configuration.
Innovation Solution
A power device comprising a thyristor and two insulated-gate switch devices connected in series between current-conduction terminals, with a Zener diode integrated to enhance switching speed and prevent current tails, maintaining a standard three-terminal configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a four-terminal power device configuration is used to achieve high switching speed and large RBSOA, then switching performance is improved, but device complexity increases and standard three-terminal configuration is lost
Solution Approach 1:
The patent merges the control functions of two separate insulated-gate switch devices into a single integrated control terminal. The first and second insulated-gate switch devices are controlled by the same control signal applied to a shared control terminal, eliminating the need for separate control terminals while maintaining the benefits of dual-switch configuration for high switching speed and large RBSOA
Solution Approach 2:
The single control terminal serves multiple functions by controlling both the first and second insulated-gate switch devices simultaneously. This multi-functional control terminal enables the device to maintain standard three-terminal configuration while achieving the performance benefits of what would otherwise require four terminals
2Device complexity
If conventional three-terminal power devices are used to maintain standard configuration, then device simplicity is maintained, but switching speed is reduced and power dissipation increases
Solution Approach 1:
The patent segments the power device into multiple functional components (first insulated-gate switch device, second insulated-gate switch device, and thyristor) that work together in series. This segmentation allows each component to contribute to high switching speed while the integrated control terminal maintains standard three-terminal configuration, resolving the contradiction between simplicity and performance
3Strength
If thyristor-based power devices are used to achieve high blocking voltage, then voltage blocking capability is improved, but turn-off time increases
Solution Approach 1:
The patent applies preliminary action by using the first insulated-gate switch device to pre-charge the thyristor gate before the thyristor is triggered into conduction. This preliminary charging action prepares the thyristor for rapid turn-off by ensuring proper gate charge conditions are established in advance, thereby reducing turn-off time while maintaining high blocking voltage capability
Data Source
AI summary
An embodiment of a power device having a first current-conduction terminal, a second current-conduction terminal, a control terminal receiving, in use, a control voltage of the power device, and a thyristor device and a first insulated-gate switch device connected in series between the first and the second conduction terminals; the first insulated-gate switch device has a gate terminal connected to the control terminal, and the thyristor device has a base terminal. The power device is further provided with: a second insulated-gate switch device, connected between the first current-conduction terminal and the base terminal of the thyristor device, and having a respective gate terminal connected to the control terminal; and a Zener diode, connected between the base terminal of the thyristor device and the second current-conduction terminal so as to enable extraction of current from the base terminal in a given operating condition.