what is an Inverter

What is an Inverter?

What is an inverter – VFD?

An inverter, specifically a Variable Frequency Drive (VFD), is a type of motor controller that varies the frequency and voltage supplied to an electric motor. Control of these elements allows for the modulation of motor speed. This overview of inverters will explore the key reasons for adjusting motor speed, delve into the benefits and integration of VFDs, and cover their common applications. We’ll compare them to other motor controllers, discuss some special features of leading VFD manufacturer, Invertek Drives, and go through the main advantages of using a VFD. Lastly, we’ll talk about power conversion, the difference between VFDs, AC Drives, and Variable Speed Drives, and the different types of VFDs.

Reasons for Adjusting Motor Speed

  1. Save energy and improve system efficiency: By controlling the frequency and voltage of the motor, VFDs allow for more efficient energy usage. This results in considerable energy savings, particularly when compared to traditional on/off motor control methods.
  2. Power conversion in hybridization applications: In hybrid systems that use battery storage, VFDs can convert power to match the energy requirements of the system.
  3. Match drive speed to process requirements: Depending on the requirements of a specific process, the speed of the motor can be adjusted using an inverter, ensuring that it operates at the most optimal speed.
  4. Match torque or power to process requirements: Not only can the speed of the motor be controlled, but also the torque or power can be modulated to meet the needs of the process.
  5. Improve working environment (reduce noise levels): By controlling motor speed, VFDs can significantly reduce the noise levels of a motor.
  6. Reduce mechanical stress on machines: Operating motors at full speed can put a great deal of stress on the machinery. Inverters allow motors to operate at lower speeds, reducing the mechanical stress and extending the life of the equipment.
  7. Shave peak consumption to avoid peak-demand prices and reduce motor size: By controlling motor speed and usage during peak-demand periods, VFDs can help avoid higher energy prices and reduce the overall motor size needed for operation.

Integration and Benefits of VFDs

The integration of VFDs within a system provides several key benefits. Energy savings are perhaps the most significant advantage, with intelligent motor control facilitating a more efficient and economical use of power. Furthermore, the networking and diagnostic capabilities of VFDs provide essential insights into system performance and potential issues. By reducing peak current through controlled motor speed, VFDs also contribute to a decrease in energy costs.

Common Applications of VFDs

The flexibility of inverters allows them to be used in various applications, but they are commonly employed for the control of fans, pumps, and compressors. These devices often need to operate at different speeds based on specific needs, and a VFD allows for this variation in operation.

Comparison with Other Motor Controllers

When compared to other motor controllers, such as soft starters and across-the-line contactors, VFDs stand out. While soft starters provide a gentle ramp-up during motor startup, they don’t allow for speed control during operation. Across-the-line contactors, on the other hand, apply full line voltage, but do not offer the control and versatility that a VFD can deliver.

Invertek Drives‘ Special Features


As a global market leader in inverters, Invertek Drives offers a wide range of drives, which are known for their high quality and customisable features. These drives are rigorously tested and optimised for peak performance. In addition, Invertek provides invaluable application knowledge and maintenance services to its customers.

Main Advantage of Using a VFD

The primary advantage of using an inverter is its ability to vary power to match energy requirements, leading to significant energy savings. Compared to Direct-On-Line (DOL) operation, the energy consumption of motors controlled by VFDs can be drastically reduced.

VFDs for Power Conversion

In hybrid systems that incorporate battery storage, Inverters play a crucial role. They can convert power to meet the energy requirements of the system, thereby optimizing the use of stored energy and extending the battery life.

Difference Between VFDs, AC Drives, and Variable Speed Drives

Despite different names, VFDs, AC Drives, and Variable Speed Drives all refer to the same device. These terms are often used interchangeably in the industry.

Types of VFDs

VFDs come in two main types: single-phase and three-phase. These can be used in various applications, with different methods of frequency and voltage control and harmonic mitigation technology.


VFDs play a pivotal role in industry, providing vital control of motor speed and, consequently, energy efficiency. If you’re looking to integrate VFDs into your system, get in touch with 258 Engineering Supplier. We offer a wide range of TECO, Mitsubishi, and Invertek Drives, with full technical support to ensure you select the best drive for your needs.

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