Power Electronics Devices and Circuits

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What is an SCR (Silicon Controlled Rectifier)?

Back

A 4-layer, 3-terminal device (Anode, Cathode, Gate) that works as a controlled rectifier, conducting when a gate pulse is applied and remaining on until the current falls below the holding current. Used in rectifiers, inverters, and motor control.

Front

What is a TRIAC (Triode for AC)?

Back

A 3-terminal device (MT1, MT2, Gate) that can conduct current in both directions, commonly used in lamp dimmers, fan regulators, and AC power control.

Front

What is the function of a UJT Triggering Circuit?

Back

A Uni-Junction Transistor generates sharp triggering pulses, with a UJT relaxation oscillator charging and discharging a capacitor to provide periodic gate pulses for SCR, ensuring reliable firing control.

Front

What is a Phase Controlled Rectifier?

Back

It converts AC to DC using controlled switching devices like SCRs, with output DC voltage depending on the firing angle (α). Types include Half-wave, Full-wave, and Bridge rectifiers, used in DC drives and power supplies.

Front

What is a Chopper (DC-DC Converter)?

Back

It converts fixed DC input to variable DC output, with types including Step-down (buck), Step-up (boost), and Buck-boost, used in DC motor control and battery charging.

Front

What is a Single Phase Bridge Inverter?

Back

It converts DC to AC using four switches (SCRs, MOSFETs, or IGBTs), with output that can be square wave, quasi-square, or PWM-controlled AC, used in UPS, induction heating, and AC drives.

Front

What is a Cycloconverter?

Back

It converts fixed AC at one frequency to variable AC at a lower frequency directly, with types including Step-down and Step-up cycloconverters, used for speed control of induction motors and synchronous motors.