A Practical Primer On Motor Drives (Part 12): Variable Frequency Motor Drives
by Ken Johnson, Teledyne LeCroy, Chestnut Ridge, N.Y., How2Power Today, Jan 16 2017
Focus:
Variable frequency drives (VFDs), variable-speed drives (VSDs), inverter drives, or, more
commonly, motor drives are systems that provide pulse-width-modulated (PWM) outputs for precise
control of the applied stator voltage and frequency. After a brief discussion of VFD uses, this
section explains VFD operation including a discussion of VFD architecture and topologies. The
latter includes a detailed description of the popular dc bus (link) topologies including the
voltage-sourced inverter, the current-sourced inverter, the load-commuted inverter and the
matrix converter or cycloconverter. This part also explains the common pulse-width modulation
(PWM) techniques—carrier-based and space-vector pulse-width modulation.
What you’ll learn:
- How to understand the operation of variable frequency drives including their different architectures and topologies
- How to understand the operation of carrier-based and space-vector pulse-width modulation techniques
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