Silicon Controlled Rectifier (SCR), also known as unidirectional thyristor, is a semi controlled semiconductor power device with four layers and three terminals (PNPN).
Features:
1. Unidirectional conductivity: Similar to a diode, but with controllable conductivity.
2. Half controlled device: can only control conduction, cannot control shutdown.
3. Self locking effect: After triggering conduction, removing the trigger signal still maintains conduction.
4. Control large with small: The small gate signal controls the large main circuit current.
5. Voltage and current resistance: capable of withstanding high currents and voltages of thousands of volts and hundreds of amperes.
6. Contactless switch: long lifespan, spark free, fast response.
7. Low cost: simple structure, high cost-effectiveness.
Applications：
1. Controllable rectification
Convert AC power into adjustable DC power for chargers, electroplating power supplies, and DC speed regulation.
2. Exchange voltage/power regulation
Control the conduction angle to adjust the output power, used for dimming table lamps, adjusting the temperature of electric heaters, and regulating the speed of fans.
3. Contactless switch/Solid State Relay (SSR)
Replace mechanical relays for fast switching in industrial automation and flammable and explosive environments.
4. Motor control
DC motor speed regulation, AC motor soft start, welding machine.
5. Overvoltage protection (pry bar circuit)
Quickly short-circuit in case of power failure to protect valuable backend equipment.
6. Inverter and frequency conversion
Used in scenarios such as UPS uninterruptible power supply, variable frequency speed regulation, and DC to AC conversion.
