You could say, a VFD is the best friend of your electric motor. Variable frequency drives (VFDs) are intelligent control devices that ensure efficient operation of electric motors, to use less energy and reduce operating costs. At the same time, they extend equipment lifetime, optimize processes, and reduce maintenance requirements.
Did you know a VFD can help you to save on your energy bill? The VFD can dramatically reduce energy consumption when compared to direct-on-line (DOL) operation, where the motor runs at full speed regardless of the demand. Using a drive, power or fuel savings of 40% are common. Sometimes the savings are as much as 80%. The roll-on effect means that use of drives also reduces NOx emissions and CO2 footprint of the systems in which they are installed.
When you understand what a VFD is and how to use it, you can get closer to reaching your climate targets, as well as winning competitive advantage. That’s why a VFD is a great asset and friend - not only to your motors, but your whole business.
VFDs for energy efficiency: VFDs intelligently control motor speed, significantly reducing energy consumption (often 40%+) compared to running motors unregulated, at full speed
Cost savings and fast return on investment (ROI): VFDs lower energy bills, reduce maintenance, and improve process control, with a typical ROI of 6-12 months
Versatile applications: VFDs and power converters optimize diverse applications, including fans, pumps, conveyors, cranes, marine propulsion, hydrogen electrolysis, and renewable energy systems
Beyond energy savings: VFDs offer benefits beyond energy savings, such as improved performance, enhanced process control, longer equipment life, and reduced emissions
Danfoss expertise: Danfoss specializes in VFDs to suit any motor type, offering a wide range of solutions, and global support for optimizing motor performance
All these names refer to the same device. VFDs are also known by various other names such as adjustable speed drives, adjustable frequency drives or AFDs, variable frequency drives, variable voltage variable frequency drives, frequency converters, VFD inverters, and power converters.
To use a VFD, connect it between the power supply and your electric motor. A VFD from Danfoss automatically tunes itself to match the motor type, for the most efficient operation. Results you can expect from installing VFDs include:
The need for energy conservation is a key driver in the development of speed control devices. And VFDs provide the optimum method of controlling the speed of electrical motors to match load demand and reduce energy costs. Even small changes in motor speed deliver significant changes in energy consumption.
Drives are also useful in
Did you know that:
Variable frequency drives (VFDs) are largely invisible, hidden in basements and electrical rooms, but nevertheless they play a major and very necessary role in modern, everyday life, by making the world and our way of living more sustainable.
The VFD sits between the electrical supply and the motor load. It controls the electrical motor speed by changing the frequency and voltage supplied to the motor. Power from the electrical supply goes into the VFD, which then regulates the power that is fed to the motor. The result? Instant energy savings.
A VFD is a type of motor controller that drives an electric motor by varying the frequency and voltage of its electrical power supply. The VFD also has the capacity to control ramp-up and ramp-down of the motor during start or stop, respectively.
Even though the VFD controls the frequency and voltage of power supplied to the motor, we often refer to this as speed control, since the result is an adjustment of motor speed.
There are many reasons why we may want to adjust electric motor speed.For example, to
Today’s variable speed drives integrate networking and diagnostic capabilities to boost control performance and increase productivity. So: reduced energy consumption, intelligent motor control, and reduction of peak-current drawn are three great reasons to choose a VFD as the controller in every motor-driven system.
- A soft starter is a solid-state device and provides a gentle ramp-up to full speed during startup of an electric motor
- An across-the-line contactor is a type of motor controller that applies the full line voltage to an electric motor
Explore Danfoss Drives products for more information. We offer both single-phase VFDs and three-phase VFDs
Find out more about soft starters from Danfoss Drives
VFDs trim your power bill.
A variable frequency drive can use VFD control to vary the power supplied to match the energy requirement of the driven equipment, and this is how it saves energy or optimizes energy consumption.
The drive can dramatically reduce energy consumption when compared to direct-on-line (DOL) operation, where the motor runs at full speed regardless of the demand. Using a VFD, speed control does not waste power (unlike regulation with a throttle valve or damper, for example), but instead adjusts the motor power to match exactly the actual demand. Using a variable speed drive, power or fuel savings of 40% are common. The roll-on effect means that the use of drives also reduces NOx emissions and CO2 footprint of the systems in which it is installed.
Case story: Read how VFDs dramatically reduce energy consumption at this Roca Group factory
A widespread use for VFDs is in power conversion for hybrid or electric systems using energy storage. Growth in electrification means power converters are in high demand at sea and on land, for fast charging, DC grids, electrolysis in Power-to-X, smart grids, energy storage and more. Explore the wide range of power conversion applications:
There are many diverse types of drive available, all widely used in industry. Both single-phase VFDs and three-phase VFDs have evolved to suit a wide variety of applications. The differences in drive types include the methods used for frequency and voltage control; and the ways in which drives mitigate harmonic distortion.
Learn more about harmonic mitigation solutions from Danfoss Drives
The three major variable frequency techniques used in drives are called pulse width modulation (PWM), current source inverter, and voltage source inverter. The PWM technique is the most common. It requires switching the VFD’s inverter power devices – transistors or insulated-gate bipolar transistors (IGBTs) – on and off many times, to generate the proper root-mean-square (RMS) voltage levels. Controlling and varying the width of the pulses is how PWM varies the output frequency and output voltage to achieve VFD control.
Tap into Drives knowledge articles, to learn more about optimizing system efficiency with VFDs
Energy bills are the biggest cost after wages in many industrial companies. You can reduce your energy bill by 20-60% by installing VFDs in the following applications:
“If all fans and pumps (globally) were equipped with VFDs, the savings would equal the entire power generation capacity of the EU. By employing drives, GHG emissions can reduce by 40% by 2040.” Source: OMDIA COP26 global report
Poor or outdated control of driven loads such as fans, pumps, conveyors and compressors is a major source of wasted energy. Many fan, pump and compressor applications still run direct-on-line (DOL) and operate at full speed. Even new equipment is built to run at fixed, full speed. In 2023, over 74% of new equipment was installed DOL, so there is still plenty of scope for improving energy efficiency.
You can typically expect to save 20-60% on the energy bill, by specifying that all fans, pumps, and chillers be fitted with VFDs. For each individual electric motor load, electricity savings due to VFD control can be as high as 80%.
By applying variable speed control to fans and pumps, you can typically achieve energy savings of 40%. This is defined by the variable torque curve. For fans and pumps, a 20% reduction in motor speed results in 50% energy savings.
Discover the energy savings achieved by fan control in air handling units (AHU), at this factory in Illinois, USA
VFDs also play a crucial role in industrial applications such as cranes and conveyors. In these applications, process optimization and precise speed and position control are the primary reasons for using VFDs. For example, the VFD offers integrated condition monitoring and anti-sway functionality. For conveyors, the VFD is equipped with integrated high-precision positioning control as an alternative to servo solutions. VFD-integrated condition monitoring (CBM) with a remote monitoring service work hand-in-hand not only to improve reliability but also create new benefits in terms of visualization and logging. While VFDs can additionally help to save energy, the savings for conveyors and cranes are unlikely to reach the 40% achieved with fans and pumps.
Learn more about the value of VFDs in conveyor and industrial crane applications
In marine propulsion, electric motors and VFDs are rapidly replacing diesel engines and mechanical systems. Without VFDs, controlling a ship's speed and direction would be impossible.As well as optimizing energy efficiency, VFDs offer a range of other benefits in marine applications. The advantages include integrated functional safety, easy integration into ship systems, compact control in limited spaces below deck, and improvement of power quality on board.
Many ships still use diesel generators to make electricity. However, fully electric ferries are quickly becoming more common.
Explore our marine case stories to learn how variable frequency control and power conversion optimize vessel performance and reduce emissions, on board and on shore.
Did you know that 26% of existing installed AC motors are fitted with VFDs? And 75% of these motors drive variable torque loads (fans, pumps and compressors). Control of variable torque loads has the potential to save the most energy, in an industrial plant. Investing in variable frequency drive (VFD) technology to control these applications, along with potential utility rebates, is one of the fastest ways to reduce your energy bills and decarbonize your plant.
Source: OMDIA COP26 global report
Discover our series: Decarbonization Explained
Europe has raised the bar on motor efficiency, with minimum IE4 motor rating mandatory for motors rated 0.75 to 375 kW, from July 2023. However, upgrading a DOL motor from IE1, IE2, or IE3 to IE4 can actually increase the energy used on a fan or a pump, due to higher slip. Therefore, we recommend installing a VFD on these motor upgrades, to ensure success in reducing system energy consumption.
Source: EU MEPS, EcoDesign regulations Europe
Did you know that 95% of electric motors are oversized or sized for the peak-load scenario? Many existing systems still operate with mechanical constriction (valves or dampers) to adapt the oversizing for partial loading. VFDs can replace the valve control to save a surprising amount on running costs for motor or driven load. And this allows you to reduce the dimensioning of your electric motor at the same time.
When investing in VFDs, the typical return on investment is as short as 6-12 months. Example: A 7.5 kW pump running 8,000 hrs annually consumes electricity costing $6,000 per year, based on electricity charge of 10 cents per kWh.
The difference between Danfoss and other drive manufacturers is that Danfoss is a global market leader in VFDs, specializing purely in drives. Our focus is sharp on building the perfect VFD for your need and we offer millions of variants. The wide range of VFD variants is designed to suit any need for AC electric motor control, from sophisticated premium drives with integrated condition monitoring intelligence, to simple soft starters for basic protection. Drives from Danfoss optimize electric motor systems running any typical motor type, such as:
Danfoss offers you the freedom to combine any motor and drive then optimize it for ultimate performance. You’re not restricted by supplier-defined drive-motor bundles. Many factors beyond efficiency class influence the best choice of VFD-motor combination. These factors include logistics, availability, and importantly, return on investment. We offer you the best possible components and full flexibility so you can fine tune system performance to suit your application exactly. An important aspect of this flexibility is the ability to use your drives with all typical motor technologies, since drives from Danfoss are designed for full compatibility. This enables significant savings in spare part inventories and in retrofit situations. The same VFD can serve many different motors during a system lifetime.
When choosing a VFD supplier, it’s wise to consider the following factors, all of which influence total cost of operation:
To optimize savings, take account of part-load efficiency. It is important to realize that the efficiency classes of the motors and motor controller are related to their nominal point. Efficiency classes do not take account of part load efficiencies, even though they represent the majority of the motor operation time.
When dealing with Danfoss, you receive a premium drive, customized to your exact requirements. Design for automated assembly (DFAA), smart manufacturing methods and test of every single drive before leaving the factory ensure you receive a reliable product on each and every delivery.
Our experts are focused on every possible detail of drive optimization and are always abreast of the newest technology. Often, we invent the newest developments. Dealing with Danfoss, you get much more than the drive itself. You also have access to our application know-how and a range of maintenance services to keep your systems running optimally throughout the drive lifecycle.