Glossary: What is a Thyristor?
The thyristor is a key power semiconductor component for switching and controlling electrical energy. Belonging to the family of four-layer devices (PNPN), it is better known by the acronym SCR (Silicon Controlled Rectifier).
⚡ Quick answer: The thyristor acts as a controlled unidirectional switch. It blocks current flow until a pulse is sent to its control terminal (the gate). Once activated, it remains conductive without a control current as long as the main current does not drop to zero.
Technical operation
The thyristor operates on the principle of regenerative latching. When a positive voltage is applied to the anode relative to the cathode, the component remains blocked. Injecting a gate current triggers an internal chain reaction that saturates the component. Unlike a transistor, the thyristor does not require a continuous control signal to remain on, which minimizes losses in high-power driving circuits.
Key characteristics
- Breakover voltage: Maximum voltage supported before unwanted spontaneous triggering.
- Holding current (Ih): Minimum anode current value to maintain the conductive state.
- di/dt and dv/dt: Rate-of-change limits for current and voltage to prevent destruction or self-triggering.
- Recovery time (tq): Time required for the component to regain its blocking capability after turning off.
