The History of the Variable Speed Drive

The introduction of three-phase AC power occurred in the 1880s,  Nikola Tesla is credited with this revolutionary invention.

Tesla’s three-phase AC motor ran on three-phase power and is one of the greatest labor-saving devices of all time, it’s completely changed our lives.. It had one significant drawback, however – it could only run at one speed. So many devices were invented to compensate, things such as belts and pulleys, sheaves, dampers, inlet guide vanes, eddy current couplings, fluid couplings and so on. All to compensate for the motor’s single speed.

It took 100 years to develop a device that could run the motor at different speeds reliably and cost-effectively. In the 1980s, variable frequency drives, or Variable Speed Drives (VSDs) were introduced.

The original 1980’s Variable Frequency drives offered a lot of spare space, so weren’t in the small packages we see now. However, the basic topology of a VFD has not changed since 1980, over the last 30 years.  Nowadays, modern drives will have the same components but will be contained in a smaller enclosure with less space, packed together, and often in multiples.  Since their invention, VSDs have now saved billions of pounds in running costs and reduced energy waste greatly.