variable frequency drives

Variable frequency drives are underrated in the modern world when we need them more than ever.

Introduction to variable frequency drives:

Variable frequency drive (VFD) have a number of other names just as; adjustable frequency drive, variable speed drive, a micro-drive, or inverter drive. It is a type of motor drive. AC motor pace and torque are governed by electro-mechanical technologies. It adopts a mechanism by varying input frequency and voltage.

Types of variable frequency drives:

Major classifications on the basis of generic topologies are as below:

  • Voltage source inverter:

This is the most common type of variable frequency drive. In these drives, the diode bridge converter stores energy, capacitor delivers voltage input to the inverter.

  • Current source inverter:

Six step waveform output operate these drives.  In these drives, SCR bridge converter stores energy, inductor delivers voltage input to inverter

  • Six steps inverter:

Variable voltage inverters are another name for it. In these drives, the principle of working is either based on the current source inverter or voltage source inverter.

  • Load commutated inverter:

These are special sort of current source inverter. In these drives, energy is stored by virtue of the DC inductor circuit.

  • Matrix converter:

These converters are AC type. It acts as a three-phase current source. Chiefly, each phase acts discriminatory to modify fixed voltage to alternative voltage.

  • Doubly fed slip recovery system:

In these drives, an inverter plays its part to covert power to the AC supply network. DC current controls the speed of the motor.

Evolution in VFDs

A lot of progress has been made in the enhancement of variable frequency drives. And it has been very prominent since the 1970s. Advancement in power technologies has improved the electricity consumption in these drives. Plus the size of the devices is now reduced. Performance is now improved regarding control and authority techniques, simulating techniques, as well as software and hardware.

Perks and benefits:

Most importantly, variable frequency drives are great energy savers. Ultimately, if we compare variable frequency drives with fixed speed drives, we can see an apparent difference in the cut back of power. Especially in speed varying gadgets.

Performance traits such as acceleration, movement, monitoring, agility, pace, stress, strain, torque, and climate conditions. VFDs are also responsible for running motor in different customized manners.


They have a wide application ranging from small gadgets to large appliances. According to statistics, in the industrial section, about 25% of the global electricity is devoured by electric motors. Henceforth, systems using variable frequency drives are more efficient and reliable to use. For instance; damper controls, fans, etc.

Existence today in market:

However, the variable frequency drives are relatively limited in the market to date. But having a glance at the positive sides of the usage of VFDs, like agility, efficiency, and economic factors, it will further expand in the coming years.