1 Answer
PWM (Pulse Width Modulation) is used in buck converters for a few key reasons related to how it helps control the output voltage efficiently. Here's a simple breakdown:
In summary, PWM is used in a buck converter to efficiently step down voltage by controlling the average voltage with a variable duty cycle, minimizing energy loss and heat generation, and providing a stable output.
- Voltage Control: In a buck converter, the goal is to step down a higher input voltage to a lower output voltage. PWM allows us to control how much of the input voltage is applied to the load by adjusting the duty cycle of the pulse. The duty cycle is the percentage of time the switch (usually a transistor) is on during each switching cycle. By increasing or decreasing the duty cycle, you can control the average voltage that reaches the load.
- Efficient Power Conversion: Switching between on and off states at high frequency (with PWM) reduces the losses compared to linear regulation. In linear regulators, power is dissipated as heat during the process of stepping down the voltage. But with PWM, the switch is either fully on or fully off, minimizing heat generation and making the process more efficient.
- Smooth Output: Even though the switch is turning on and off rapidly, the output voltage can be smoothed using an inductor and capacitor. These components filter the switching waveform, providing a stable DC voltage at the output, even though the input is being pulsed.
- Control Over Current: PWM helps control the amount of energy delivered to the load. By adjusting the duty cycle, you can control how much current flows to the load, which helps regulate the power output from the converter.
In summary, PWM is used in a buck converter to efficiently step down voltage by controlling the average voltage with a variable duty cycle, minimizing energy loss and heat generation, and providing a stable output.