What is a combination of an AC motor and a generator called?

The combination of an AC motor and a generator is correctly referred to as a motor generator. This device effectively allows the conversion of electrical energy from one form to another, typically transforming AC electrical energy into DC electrical energy or vice versa. The operation involves using the motor portion to draw electrical energy from an external source and mechanically coupling it to the generator portion, which converts that mechanical energy back into electrical energy.

Motor generators are often employed in applications where precise voltage control or power stability is required. They can be found in various systems, including those that need smooth transition between different types of power supplies or in specialized industrial settings.

An MG set, although related, typically refers to a system where a motor-generator is used as a complete set, emphasizing the assembly rather than the individual components. An AC-DC converter, on the other hand, is a specific device that converts alternating current to direct current without the aspect of mechanical motion involved in a motor generator setup. An induction generator specifically refers to a type of generator that operates by using induction principles, and while it shares similarities with motor generators, it does not encompass the full combination of a motor and generator working together as a single operation.