Voltage Current Characteristics of Insulated Gate Bipolar Transistor (IGBT)

What are the three terminals of a power IGBT?
Which is suitable for making the Variable frequency drives?
What is the controlling parameter in IGBT?
What is the structure of the IGBT?
For the power semiconductor devices IGBT, MOSFET, Diode and Thyristor, which one of the following statements is true?