How an AC Drive Works

Posted November 27, 2019 by Pepper Hastings

Categories: Blog

Hi, Adam Ring here with Innovative IDM. I want to take a few minutes and explain a little bit about how an AC drive works. Really basic. First, we start off with the sine wave, an AC sine wave, typically three phase power or we can also use single phase power as well.

So we take that and we send it through a bridge rectifier, or series of diodes basically, convert that AC into DC. It starts off and it's a sine wave. Once it goes through the rectifier, it basically flips all the bottom half's up and makes DC (direct current). We store that in these large capacitors, sometimes we call them water towers, and that basically is our source for what we are going to use to generate a synthetic AC sine wave out to a motor.

Then, we take that DC and we go through a series of transistors which are basically electronic switches. We use that to create a synthetic sine wave, where we can vary the voltage and the frequency in order to get a motor to spin at a given rate.

If we keep the ratio of the voltage to the frequency consistent, then we can produce constant torque throughout slow speeds all the way up to the base speed of the motor. In some cases we can even go up beyond the base speed of the motor.

So, in a nutshell that's how an AC dive works. If you'd like to learn more, please visit us at We're the home of the legendary customer experience!

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