What is a frequency inverter and what is its application?


Over time, the power electronics have made it easier and cheaper to drive electric motors at variable speed. Therefore, systems that previously used direct current (DC) motors for ease of control, can now also use alternating current (AC) motors. This happens thanks to frequency inverters that can also be called frequency converters.

The electronics through microprocessors and microcontrollers have helped a lot in the process of evolution of the drive of the machines (AC). This evolution allows the development of complex functions in increasingly shorter processing times. As electronics are evolving more and more rapidly, it is easier to implement sophisticated control algorithms that enable high-performance drive-in series induction motors.

To exemplify this, we can mention that the induction motors can be driven by frequency inverters. This would replace flow control systems with valves (pumps) or fans. So, in this exchange, besides maintaining the functions, we obtained several advantages.

The improvement in automation processes guarantees an increase in production and a reduction in expenses. Therefore, several types of equipment were developed, aiming to meet the most diverse demands and applications of the residential and mainly industrial sectors. Among the most used equipment, we can mention the frequency inverter, which is undoubtedly one of the most versatile and dynamic components that have ever been invented.

Three-phase motor characteristics

The three-phase motor has a constant speed, but it can vary depending on the loads that are coupled to the motor. It is also important to inform that the use of a frequency inverter can also influence the speed of the three-phase induction motor.

The operating principle of a three-phase motor is based on a rotating magnetic field, which arises when an alternating current supply system is applied to poles that are 120º apart. It is important to note that starting an induction motor directly requires a current around six to seven times that of its rated current.

What is a frequency inverter?

The function of the frequency inverter is to generate an adjustable three-phase voltage and frequency, with the objective of controlling the speed of a three-phase induction motor. When these motors are fed directly from the electricity distribution network, they have a constant speed characteristic.

Various models of frequency inverters.

Frequency inverter: What are the benefits?

The main advantage of a motor-driven by a frequency inverter is energy savings and improved performance of machines and equipment. But there are many other benefits that you can check out in the list below!

  • Considerable reduction in peak current at engine start.
  • Increased equipment life
  • Lower maintenance index.
  • Control the speed of electric motors.
  • Possibility to start engines smoothly
  • Replacement of mechanical and electromagnetic drives.
  • Advanced communication and data acquisition.
  • Reduces the noise level.

Thanks to these mentioned advantages, the use of the frequency inverter makes the three-phase motor ideal for almost all types of operations found constantly in the industry.

How the Frequency Inverter works

As we said before, the frequency inverter is an electronic device whose main function is to vary the rotation of a three-phase motor, through the frequency variation that it provides in its output contacts. That way we can easily control the speed at which the engine will work.

The frequency inverter works by changing the frequency at the motor input. The motor speed variation is directly proportional to the frequency variation, that is, if the frequency increases the motor speed also increases, and if the frequency decreases the motor speed also decreases.

To complement the content on frequency inverters, the video below the Mundo da Elétrica channel also explains in detail how a frequency inverter works and what are its applications.