Introduction to Variable Frequency Drive (VFD)

In the previous chapter, we learned about the various types of electric motors. Among the various types, the asynchronous (induction) motor is the most commonly used motor in the industry. However, machines in the industry, such as conveyors, mixers, agitators, pumps, compressors, and others, that utilize an induction motor require a variable speed, which an induction motor alone cannot provide because induction motors are designed to run at a constant speed (that is, their speed remains almost the same for various load range).

A variable speed drive is an electronic device used to achieve the varying speed needed by either an asynchronous or synchronous motor for various applications.

This chapter looks at a Variable Frequency Drive (VFD), its working principle, benefit, wiring, and programming. We will also look at some practical applications, including forward, reverse, and speed control of an induction motor.

In this chapter...