Buck chopper

Buck chopper

Buck Chopper

A Buck Chopper (also called a Step-Down Chopper) is a type of DC–DC converter that is used to obtain a lower average DC output voltage from a higher DC input voltage. It is one of the simplest and most widely used chopper circuits in power electronics.

Working Principle

• The circuit consists of a power electronic switch (MOSFET/IGBT/thyristor), a diode, an inductor, and a filter capacitor.
• The switch operates at a high frequency using Pulse Width Modulation (PWM) control.
• By controlling the ON time (Ton) and OFF time (Toff) of the switch, the average output voltage (Vo) is controlled.

Vo=D⋅VinV_o = D \cdot V_{in}Vo​=D⋅Vin​

where D = Ton / (Ton + Toff) is the duty cycle.

Thus, the output voltage is always less than the input voltage.Modes of Operation

1. Continuous Conduction Mode (CCM) → Current through the inductor never falls to zero.
2. Discontinuous Conduction Mode (DCM) → Inductor current falls to zero during part of the switching cycle.

Key Features

• Steps down DC voltage (Vo < Vin).
• Smooth and regulated output using LC filter.
• High efficiency due to switching operation.
• Compact size and suitable for portable electronics.

Applications

• DC motor speed control
• Battery charging (EVs, UPS systems)
• Renewable energy systems (Solar PV to DC loads)
• Power supplies for electronic devices (laptops, mobile chargers, LED drivers)