Variable frequency drives (VFD) have been used for HVAC systems in buildings for more than 40 years. But only in recent years, driven by their advanced energy savings features, variable frequency drives have been installed to an increasing number of HVAC systems inside a building.

Variable frequency drives are electronic panels subject to the conditions in which they are located. Many times, variable frequency drives are located in HVAC building's rooms or roofs with no air conditioning. The enclosure type is important because it affects the reliability of the variable frequency drive. High temperatures, moisture and dust can lower variable frequency drive efficiency and create operational issues. Most variable frequency drive manufacturers have several options for NEMA-rated enclosures, depending on the environment and need.

China total potential market capacity of variable frequency drive (VFD) should be 120 to 180 billion Yuan, which accounted for about 60% of low voltage VFDs, middle voltage and high voltage VFDs share 40 % market. Currently, high-voltage VFD's applications include: metallurgy, petrochemical, power plants, urban water supply system, most use for fans and pumps. Due to the high-voltage power electronic devices constraint, high voltage VFDs have not been used widely which is less 20%, it needs the suppliers make further marketing promotion.

Technology is always the basic of a brand to survive in the market. China domestic manufacturers should establish their own research and development efforts to improve the VFD technology level, creating new drives to adapt to market demand. For a long time, China VFD suppliers are in the low-end technology level among the global markets, but in recent years, the manufacturer realizes it's better to improve their own R & D abilities and production lines capabilities, rather than to emulate someone's technology. China variable frequency drive manufacturers establish their own R&D teams base on domestic market demand, build their own brand and increase market share, thus, compete with foreign VFD brands in near future.

Sales of VFDs technology are now growing at a rate of more than 5% per year, according to Steve Ruddell, U.K.-based general manager of VFDs and motors for ABB, yet market penetration is still surprisingly low. Although ABB believes the global VFDs market to be worth around $6 billion — and its own market share to be nearly twice as big as its nearest competitor — it says only about 5% of all motors are controlled by VFD. That figure increases to nearly 20% for higher drives power applications. The U.S. Department of Energy estimates that the 40 million motors used by U.S. industry account for 70% of its electricity consumption — and that up to 18% of that energy could be saved by applying proven efficiency technologies such as variable frequency drives.

With potential energy savings of that order, it's not surprising that short payback time on capital investment has long been a selling point put forward by VFDs suppliers. "Price remains a factor, but overall, prices are falling as VFDs become more of an off-the-shelf commodity," says Geraint Evans of Control Techniques, Newtown, Wales, the U.K. manufacturing division of Emerson Control Techniques, Eden Prairie, Minn. "The paradox here, of course, is that purchasing decisions are therefore more likely to be made on capex [capital expenditure or cost] rather than opex [operating costs] grounds, so short payback periods stemming from reduced running costs become less of a consideration." In such a price-sensitive market, functionality becomes more of a key factor with several technology trends emerging as the VFDs manufacturers strive to make their products as user-friendly as possible.