Relay-Based PWM: Feasibility and Alternatives > 자유게시판

Using relays for pulse width modulation (PWM) control is not recommended and typically fails for everyday electronic systems. These devices function as mechanical contactors designed to interrupt or complete electrical paths by mechanically actuating terminals, and are fundamentally incompatible with rapid switching. The nature of their internal mechanism imposes critical performance barriers that render them unsuitable for PWM. Most commercial relays can operate at frequencies below 10 Hz, while PWM necessitates switching frequencies of up to thousands or even tens of thousands times per second to precisely control power to power-hungry electronic components.

When you try to use a relay for PWM will quickly uncover multiple serious drawbacks. First, switching arms fail prematurely under off cycles, leading to unexpected malfunction. Second, transition rate is far too slow to maintain consistent energy modulation. What you get instead is repetitive mechanical bangs and jittery energy fluctuations that can cause mechanical resonance, acoustic interference, or erratic behavior انواع رله in lighting systems. Lastly, back EMF surge generated when motors or solenoids de-energize can damage the relay contacts and compromise the connected microcontroller or driver chip.

To achieve effective pulse width modulation, you should employ solid state switches such as MOSFETs or IGBTs. These devices can operate at frequencies exceeding 20 kHz over billions of cycles and at extremely high efficiency. can be controlled via programmable logic circuits to provide precise control over the average power delivered to a connected appliance. An N-channel MOSFET paired with a proper gate driver and a thermal management system can handle high currents and deliver reliable output waveforms reliably.

In cases where your setup that demands pulse width modulation and you are limited to electromechanical switches, you should rethink your architecture. Employ the relay only as basic state toggling, and implement PWM using a solid state component. For example: you might use a relay to turn a large heater on for a full cycle and a solid-state switch to modulate LED intensity within that cycle.

In summary, relays are not a practical tool for PWM control. The reliance on moving parts makes them too slow, audibly disruptive, and too unreliable for the high-frequency switching that this application requires. Always choose semiconductor switches like MOSFETs or transistors when you need PWM. They are faster, quieter, exhibit higher energy efficiency, and far more durable for this type of application.