AC Drives and DC Drives are used to regulate the speed of an electrical motor. There are two predominant types of drives that exist, namely, DC (Direct Current) drives and AC (Alternating Current) drives. They do this by converting the frequency of the electrical supply into a frequency that is suitable to power the motor. A DC drive regulates the speed system of a DC motor, while an AC drive is a speed regulator for an AC motor.

A DC drive converts alternating current into direct current, which then powers and runs the DC motor. It is a simplistic drive that makes use of multiple thyristors. Depending on the number of thyristors, they create either a half cycle or full cycle of DC output.

An AC drive converts an AC current to a DC current, and then converts that current back into an AC current. This is known as a double conversion, and is executed because it increases the current’s output dramatically, while keeping the motor coil intact.

AC/DC Drives Basics and How They Differ 

Other than the contrasting currents they produce, there are a few key differences between an AC and DC drive.

• DC drives produce high torque, and are perfect in circumstances where constant speed is an important requirement. AC drives on the other hand, are built to handle brisk speed changes.
• DC drives require more maintenance due to the presence of brush assemblies and communicators.
• AC drives are energy efficient, providing effective energy generation that does not consume as much energy as their counterpart.
• AC drives are more complicated than DC drives; however, they are more programmable and have a multitude of safeguards.

There are other differences, but these are the biggest distinctions between the two.

Which is Better, an AC Drive or DC Drive?

AC drives have become more popular over time; however, there are certain applications that still prefer DC drives. Some of these include elevators, textile mills, spindle drives, machine tools, winders, excavators, crushers, and more.

The reason that AC drives have become so popular is that they offer more when it comes to process control, they reduce the mechanical stress placed upon and experienced by motor control applications, as well as optimise the performance of machinery that make use of electrical motors.

Ultimately, the “best” drive for the job is determined by the requirements of the machinery and operations. To find out more about AC and DC drives, and which one would be best suited to your applications, contact us at EP Normand.