This series brings topics answering basic questions around VFDs such as fundamental components of VFDs, drive system components, working principles, dimensioning considerations etc.
AC versus DC drive For decades DC drive was a preferred choice for variable speed motors due to its easy and accurate way of speed or torque control. However, the development of AC drives changed the competitive landscape and paved the way for AC drives. What was the reason for Read more
VFD control: An introduction In this post we introduce basic thoughts on VFD control. Some of you asked deeper questions about different motor control strategies and their benchmark. Such comparison will be subject of a separate post, resp. a dedicated motor control series. Today’s article provides a base for further Read more
Selection of a variable frequency drive In this post we walk through some aspects regarding selection of a variable frequency drive. Variable frequency drives, often abbreviated as VFD, VSD or ASD, are means to achieve energy savings [1] and to enable position, speed or torque control of electric motors. Meanwhile, Read more
Current, voltage and power scaling of VFD Variable frequency drives (VFD) became unthinkable part of industrial motor drives. They cover voltages from some 120 V up to 13.8 kV (special designs go even higher) and power range from fraction of kW until 100 MW and beyond. Enabler of such wide Read more
Advantages of liquid cooled drives This article deals with liquid cooling for high power variable frequency drives (VFD). What is the principle of liquid cooling? What kind of liquid can be used for cooling? What are the advantages of liquid cooled drives? Continue reading this post on advantages of liquid Read more
Does a VFD pay off? In turbulent times companies are cautious of making investments. However, exact these periods are times when specific companies set apart from the others by making smart decisions. VFD can reduce the energy consumption, make the production more flexible and improve the quality of the products Read more
Load types and characteristics Type of load is relevant for VFD hardware dimensioning and selection of most suitable VFD topology [1]. Sometimes the load type determines what kind of rectifier (front end) is required. Also, load type may affect some options and features that the VFD shall have. Therefore, it Read more
VFD catalog rating You have surely noticed that most manufacturers have catalogs and brochures with tables listing their VFD types along with basic information such as rated output current, motor shaft power, cooling requirements, enclosure type, dimensions, weight etc. What is behind this VFD catalog rating and how to understand Read more
Current source and voltage source inverter Current source and voltage source inverter are the two basic types of indirect frequency converters. Therefore, it might be very interesting to describe and compare both types. This article can also be seen as an amendment to the LCI vs VSI series [1] that Read more
Dry type transformer technologies Transformers can be classified based on their insulation system in two major groups: liquid filled and dry type. Liquid filled (immersed) use either mineral oil or some alternative type of insulation liquid (silicon oil or esters). Dry type technology also has several sub-categories. The terms might Read more