Answer to Question 23.

11. What is a controlled rectifier?

A controlled rectifier is a single or three phase bridge rectifier configured with diodes in the negative to ac connections and transistors or more commonly thyristors between the ac and positive connections.

By controlling the thyristor firing angle (a specific point in the cycle when conduction of the thyristors is required and gate triggering occurs causing the thyristors to turn on) the avarage output voltage and/or current can be controlled on a cycle by cycle basis.

With a fast controller, power supplies are easily manufactured whilst slower controllers are ideal for battery chargers.