Class C or complementary commutation

In power electronics, commutation refers to the process of turning off a thyristor or a group of thyristors in a controlled manner. It is an essential step in order to maintain the flow of current in a desired direction.

One type of commutation is known as class C or complementary commutation. This type of commutation is used when the load current of a thyristor needs to be transferred to another incoming thyristor.

Load commutation
Load commutation, also known as class A commutation, is a method where the commutation is achieved by transferring the load current of a thyristor to a parallel connected thyristor. However, load commutation has some limitations, such as a high voltage drop due to the transfer of current through the load and a large power loss.

Resonant commutation
Resonant commutation, also known as class B commutation, is a method where the commutation is achieved using resonant circuits. This method is used to reduce the voltage and power loss during commutation.

Impulse commutation
Impulse commutation, also known as class D commutation, is a method where the commutation is achieved by applying a high-voltage pulse across the thyristor to turn it off quickly. This method is suitable for high-power applications but requires complex circuitry.

Complementary commutation
Complementary commutation, also known as class C commutation, is a method where the load current of a thyristor is transferred to another incoming thyristor. This is achieved by applying a reverse voltage across the incoming thyristor, causing it to turn on and carry the load current. The original thyristor is then turned off.

Complementary commutation offers several advantages over other commutation methods. It reduces the voltage drop across the load, leading to lower power loss. It also allows for higher efficiency and improved system performance. However, it requires careful design and control of the circuit to ensure proper commutation.

In conclusion, the type of commutation where the load is transferred to another incoming thyristor is class C or complementary commutation. This method offers advantages such as reduced voltage drop and improved efficiency in power electronic systems.