Frequency converters
Frequency Converters and Soft Starters – Efficient and Reliable Control for Your Equipment. Discover solutions that ensure lower energy consumption and a longer lifespan for your devices.
Frequency converters
Motor drives (VFD)
Variable frequency drives for precise speed and torque control in industrial systems.
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Frequency converters
50/60 Hz frequency converters
Reliable network frequency conversion between 50 and 60 Hz — power equipment for another network: from compact models to high-power industrial solutions.
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What is a frequency converter and how does it work?
How does a frequency converter control the speed of a motor?
A Variable Frequency Drive (VFD) is an electronic device that controls the speed and torque of an AC electric motor by changing the frequency and voltage of the electric current supplied to the motor. The AC current from the power supply is first converted to DC by a rectifier, and then re-formed into AC current of the required frequency and voltage in an inverter. This allows the motor speed to be precisely adjusted to the actual process demand – the pump, fan or conveyor rotates as much as is actually needed at that moment. This reduces energy consumption, mechanical load and equipment wear, and the technological process becomes smoother and more accurate.
Danfoss iC2 – compact frequency converters for everyday tasks
iC2-Micro – the next generation micro drive, replacing the popular VLT® Micro Drive FC 51
The Danfoss iC2-Micro is a compact frequency converter designed for OEMs and simpler drive applications where reliability, quick start-up and optimal cost are key. Despite its small dimensions, the iC2-Micro has a wide range of programming functions, an integrated EMC filter and a braking transistor, making it easy to adapt to conveyors, fans, pumps, mixers and other mechanisms.
The device is operated via an intuitive control panel, and parameters can be quickly copied from one drive to another. With its robust design and reliable overload protection, the iC2-Micro is suitable for both single machines and series production. It is the direct successor to the legendary VLT® Micro Drive FC 51 - a modern platform for which Danfoss ensures long-term support and spare parts supply.
Danfoss iC7 family – a new generation drive platform
The iC7 series includes specialized solutions for different industrial sectors – from automation to water management
iC7-Automation: universal frequency converter for industrial automation - conveyors, cranes, extruders, mixers and other demanding mechanisms. High shaft torque accuracy even at zero speed, automatic motor adaptation at standstill.
iC7-HVACR: Designed for heating, ventilation, air conditioning and refrigeration systems. Provides quiet and efficient operation of fans, pumps and compressors, integrated condition monitoring and seamless integration into building management systems.
iC7-HVACR ULH (Ultra Low Harmonic): Ultra low harmonic distortion version – total harmonic distortion (THDi) less than 3 %, while a standard inverter produces around 40 %, and an inverter with a passive filter produces 5-10 %. The power factor is close to unity, so no additional harmonic suppression equipment is required. Ideal for hospitals, data centers and buildings with limited power grid capacity.
iC7-Aqua: a new generation inverter for water management – water supply, wastewater, desalination and irrigation systems. Specialized pump control functions, dry-running protection and advanced multi-pump cascade control.
The entire iC7 platform is modular: power from 0.37 to 710 kW (system modules – up to 2700 kW), dual Ethernet port with PROFINET, Modbus TCP, EtherNet/IP and EtherCAT support, standard STO SIL3 / PLe functional safety and hardware cyber protection according to the „secure by design“ principle.
Thanks to their modular architecture, iC7 drives are easily expandable and adaptable – from a single machine to an entire factory or ship’s electrical system.
Harmonic distortion comparison (THDi)
THDi is a measure of total harmonic distortion of the current. The lower it is, the cleaner the electrical network, the lower the load on transformers and the longer the service life of the equipment.
Standard converter
An inverter with an integrated choke coil is the simplest and cheapest option, but it returns high distortions to the grid.
~40 % THDi
Low Harmonic Solution
Converter with a separate passive harmonic filter – distortion is significantly reduced, but requires additional cabinet space and installation work.
5–10 % THDi
Ultra Low Harmonic (ULH)
iC7 ULH converter – active filtering integrated in a single housing: power factor close to unity, no additional equipment required.
< 3 % THDi
Lower THDi means less transformer overheating, less interference to sensitive equipment, and smoother compliance with network quality requirements (IEEE 519 / IEC 61000).
VACON® family for heavy industry
Proven solutions for the most demanding industrial tasks
VACON® 100 INDUSTRIAL: versatile industrial frequency converter from 0.55 to 800 kW. Easily integrated into all major control systems – installed both as a module and as a closed cabinet solution.
VACON® 100 FLOW: a specialized version for pump and fan control. Dedicated flow control functions – multi-pump cascade, dry-running protection, pipeline filling mode – help save energy in water and HVAC systems.
VACON® NXP: highly dynamic drive for high power and system solutions – cranes, lifting equipment, marine drives, metal and mining industries. Air or liquid cooled versions, power up to several megawatts.
VACON® NXS: a proven, robust platform for standard industrial applications where durability and stable operation in demanding conditions are key.
VACON devices are renowned for their exceptional resistance to dust, vibration and temperature fluctuations, which is why they are often chosen by companies in the pulp, metal, mining and marine industries.
Soft starters – for smooth motor start-up
VLT® Soft Starters protect the motor and machinery during start-up
Soft starters smoothly start fixed-speed motors - by gradually increasing the voltage, they prevent current surges, belt slippage and water hammer in pipelines.
The range includes the smart VLT® Soft Starter MCD 600 with adaptive start and comprehensive motor protection and the economical VLT® Compact Starter MCD 201 / MCD 202 for motors up to 110 kW. This is the optimal choice when speed control is not required, but it is important to protect the machinery and the electrical network.
How to choose the right frequency converter?
Motor power and current: The inverter is selected based on the rated motor current, not just the power.
Load nature: normal load mode is sufficient for pumps and fans, cranes and conveyors require a larger overload margin.
Environmental conditions: temperature, dust and humidity determine the required enclosure protection class (IP20–IP66).
Network quality requirements: in sensitive systems, it is worth choosing low harmonic (Low Harmonic or ULH) solutions.
Communication: PROFINET, Modbus TCP, EtherNet/IP or other bus compatibility with your control system.
„Invertas engineers will help you select the optimal model based on your technical requirements and budget - contact us for a free consultation.
FAQ
What is the difference between a frequency converter and a softstarter?
The frequency converter continuously regulates the motor speed throughout the entire operation, while the soft starter only softens the start and stop - after reaching the rated speed, the motor rotates at the mains frequency. If speed regulation is not required, a soft starter is a more economical choice.
How much energy does a frequency converter help save?
The energy consumption of pumps and fans depends on the cube of the speed, so even a small reduction in speed results in significant savings - in practice, an average of 40 % of energy is saved, and the investment often pays off within 1-2 years.
What is harmonic distortion?
This is a distortion of the mains current waveform caused by power electronics. High distortions overheat transformers and disrupt sensitive equipment. Danfoss ULH inverters reduce THDi to less than 3 % without additional filters.
Can PM and SynRM motors be controlled?
Yes. Danfoss iC2, iC7 and VACON drives control not only induction (IM) but also permanent magnet (PM) and synchronous reluctance (SynRM) motors. The automatic adaptation function adapts the drive to the motor in seconds, without the motor rotating.
Do frequency converters have functional safety?
Yes. The iC7 series has the Safe Torque Off function STO SIL3 / PLe integrated as standard, and the PROFIsafe safety protocol is optionally available via the communication bus. VACON NXP offers a wide range of certified safety functions (STO, SS1, SLS, etc.), so the drives can be integrated into machine safety systems without additional external components - which reduces costs and speeds up certification and commissioning.
Can one inverter power multiple motors?
Yes, if the total motor current does not exceed the inverter's rated current - this is how fan groups are often controlled.
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