1 Answer
The purpose of forced commutation in SCR (Silicon Controlled Rectifier) applications is to turn off the SCR in situations where the natural commutation (the SCR turning off when the current through it falls to zero) is not possible or practical.
In an SCR, once it is turned on by a trigger pulse, it remains on until the current through it drops to zero, at which point it can turn off naturally. However, in many applications, especially those involving DC circuits or circuits where the current does not naturally cross zero (such as in certain motor control applications), the SCR will stay on indefinitely.
Forced commutation is used to artificially "force" the SCR to turn off at a desired time by momentarily interrupting or reducing the current through it, even before it naturally reaches zero. This is important in circuits like inverters, motor drives, or other controlled power electronics systems where precise control over the switching of the SCR is needed.
Key points about forced commutation:
In summary, forced commutation is crucial for effectively controlling the SCR in AC or DC circuits, ensuring that the SCR can be turned off reliably in applications where natural commutation cannot occur.
In an SCR, once it is turned on by a trigger pulse, it remains on until the current through it drops to zero, at which point it can turn off naturally. However, in many applications, especially those involving DC circuits or circuits where the current does not naturally cross zero (such as in certain motor control applications), the SCR will stay on indefinitely.
Forced commutation is used to artificially "force" the SCR to turn off at a desired time by momentarily interrupting or reducing the current through it, even before it naturally reaches zero. This is important in circuits like inverters, motor drives, or other controlled power electronics systems where precise control over the switching of the SCR is needed.
Key points about forced commutation:
- It ensures that the SCR can be turned off at a specific time, regardless of the current waveform.
- It allows the SCR to be used in applications like DC motor control, where natural commutation is not feasible.
- It typically involves the use of additional components like capacitors, inductors, or external circuits to create the necessary condition to interrupt the current.
In summary, forced commutation is crucial for effectively controlling the SCR in AC or DC circuits, ensuring that the SCR can be turned off reliably in applications where natural commutation cannot occur.