What is the Frequency of Inverter Control?

When it comes to electric motors and energy efficiency, frequency inverters (also known as Variable Frequency Drives) are essential. For people who work in an industrial capacity or for those looking to purchase an inverter, understanding how they control frequency is important.

This article covers what frequencies inverters use, how they control the frequency of an AC electric motor due to the type of power supply they provide, and what that means for you as the end-user. In this article, we’ll answer the frequently asked questions many buyers and researchers have about frequency.

Frequency Inverter Control

The frequency inverter (known as VFDs or variable frequency drives) is an electrical device designed to control the speed of an AC electric motor and can change the speed of a motor by controlling the frequency of the electricity supplied. When the frequency of power changes, the speed of the electric motor also changes as well as the amount of torque created, and in many cases, the amount of electricity used. In general, frequency inverters are most commonly used in industrial automation, HVAC systems, and pumps.

How Does an Inverter Control Frequency?

To control an AC motor with an inverter, it must convert the AC electric company’s fixed frequency input to a variable frequency output. Here is the process of how it operates:

• AC power goes through the rectifier to convert AC to DC.
• DC voltage will then be filtered and stored in various capacitors to stabilize the DC voltage for continuous power.
• The DC voltage is then fed to the inverter, which converts the DC back to AC at a variable frequency that will then supply to the motor.

The frequency conversion and frequency adjustment allow for precise control over how motors operate, which leads to greater system efficiency and reduces wear and tear.

Inverter Frequency Range

The range of frequency that can be operated on by an inverter is a significant feature of frequency inverters. Inverter frequencies generally range from 0 Hz to 400 Hz. The lowest frequency range of an inverter, 0 Hz to 50 Hz, will enable you to utilize variable speed drives for adaptive motor control. Conversely, higher frequency ranges up to 400 Hz will allow for operation within high-speed applications.

When purchasing an inverter, it is important to consider the frequency required for the motor application as well as the type of motor being used. For example, low-frequency inverters will work well in low-speed applications (e.g., conveyor belts); however, if your application requires more accuracy and precision (e.g., robotics or CNC), then you should choose a high-frequency inverter.

Maximum Frequency of an Inverter

Each inverter’s maximum frequency is dependent upon the specific model and manufacturer of the inverter. In terms of frequency, most standard inverters can work with a maximum of 400 Hz. However, some advances have been made by creating unique frequency inverters that can operate much higher than 400 Hz and will go up to 1000 Hz or sometimes even more than that. High-frequency inverters are primarily used in industries that require extremely high speeds and precision and are generally found within the aviation industry and the manufacture of high-speed machinery.

Advantages of Frequency Control

There are numerous reasons why controlling frequency is beneficial to industrial and commercial processes:

• Energy Efficiency: By controlling motor speed based on the load, frequency inverters reduce the amount of energy used unnecessarily.
• Increased Equipment Life: Continuously using an electric motor in a smooth manner will reduce wear and tear, thereby extending the useful life of equipment.
• Improved Process Control: Accurate adjustments will provide a greater ability to control the processes in an industrial setting, thereby increasing both productivity and product quality.

When selecting an inverter for your industrial production facility or an inverter to improve energy usage in your commercial building, choosing the appropriate inverter with adequate frequency control capabilities can help you save time and money as well as conserve energy.

Frequency Inverter Control FAQs

How does an inverter control frequency?

When a frequency inverter controls frequency, it converts a constant frequency AC power supply to a variable frequency output. This is accomplished through the use of a rectifier, capacitor, and an electronic switching device (outside of the rectifier) to give very accurate control of the motor speed being powered.

What is the frequency range of an inverter?

The average inverter has a frequency range from 0 Hz to 400 Hz. Additionally, many manufacturers and vendors sell specialized frequency inverters, which are designed to provide higher frequencies than 400 Hz. Low-frequency inverters are typically utilized for low-performance applications, while high-frequency inverters are required for high-precision and high-speed applications.

What is the maximum frequency of an inverter?

The actual maximum frequency of an inverter is dependent upon the design of the inverter being utilized. Standard inverters typically do not operate above 400 Hz. However, some specialty applications, such as using an inverter for very high-speed applications, may have frequency capabilities exceeding 1000 Hz.

Things to Consider When Selecting a Frequency Inverter

To ensure you select the correct frequency inverter, you should consider the following:

• Application Requirements: Determine whether you need a low-frequency or high-frequency inverter. For example, low-frequency inverters are often used; however, if you are manufacturing steel, you will need a very high-frequency inverter.
• Energy Efficiency: If it is essential for your business to save money on electricity costs, you should consider a high-energy-efficient inverter that has features such as regenerative braking and optimized switching.
• Expandability: In the event of potential growth in your operations, ensure any inverter you are considering will allow you to expand your frequency inverter needs in the future.
• Brand/Trustworthy Manufacturer/Reliability: It is always best to choose a well-known brand and a good model to ensure that the inverter will perform smoothly and has a long service life.

Keeping these factors in mind will help you select an inverter that delivers lasting efficiency and cost savings. Always review the manufacturer’s specifications carefully before making your final decision.

Summary

Frequency inverters play a critical role in modern motor-driven systems by controlling the frequency of AC power supplied to the motor. They improve energy efficiency, extend motor life, and enhance process quality. Whether you need a low-frequency unit for routine tasks or a high-frequency model for specialized applications, reviewing your specific application, efficiency goals, and desired performance range before purchasing will help you choose the right inverter.