Need Help On Speed Control Of Single Phase AC Induction Motor

8000 what, RPM ? are you sure it is an induction motor and not a universal motor ?.

Anyhow, if it's a universal motor, go phase angle with a triac, if it's an induction motor go PWM with IGBTs.

Hi

Thank you for your reply. yes, im using induction motor and what 8000 meant is rpm. i would be using a closed loop control system. so by using pwm igbt method we could control speed without overshoot ( there will be a load of min 1 kg )

Certainly; but do you actually have to design the driver ? why don't you just buy a single phase AC inverter, VFD or variable speed AC drive (being these all names given to the same apparatus).

Closed loop control without overshoot is achieved by correct selection of the gain, integral action and derivative action within the controller given the process to which it is attached; these are called tuning parameters. Tuning has to happen on any control loop, so it doesn't matter what is there in terms of driver and driven equipment.

Google "Ziegler-Nicholls" for more guidance. There may even be an article on the topic in Wikipedia.

Ignator has also expressed the same doubt. Let me explain why 8000 RPM induction motors are not found anywhere:

The RPMs of an induction motor are equal to 120 multiplied by the frequency of the supply lines and then divided over the number of poles.

(120*Freq.)/#of poles

The maximum RPM for this type of motor is 3600, I haven't seen motors of less than two poles, or power grids of over 60Hz.

In my previous post I asked you if you had to design the driver, do you have to ?.

You need to tell us a lot more about your project.

Thanks for your reply. By applying variable frequency can we not get an higher RPM?

Yes by varying the Hz you can obtain higher RPM.... what about the voltage?

8000RPM... and what frequency do you need for that at 220v 1ph for a two pole motor?

As the project includes a speed controller, how about a series-wound brushed-commutator motor?

I found a motor that might do it, but it's max RPM is only 6500...

http://www.parvalux.eu/parvalux/upload/pdf/kommutator1.pdf

Of course you can, that is just one standard feature of a VFD, but you're saying in your original post that the motor you will use, has already a nominal speed of 8000 RPM; or maybe you meant that 8000 RPM is your target speed ?.

Please double check that, or you'll start having all sorts of different answers, which can be correct in the realm of an assumed application, not necesarily yours.

Give us the correct nameplate of the motor.

I'm confused by 8000 RPM. The best a single phase 2 pole induction motor can do is 3600RPM@60Hz, or 3000RPM@50Hz. Or am I not understanding some magic going on here, like a country that has 133Hz power grid.

That, and I'm not aware of any speed control that can maintain enough torque for a single phase induction motor. I may be wrong and someone has created such a product in my failure to watch what is going on.

Yes there are single phase INPUT VFDs that are connected to 3 phase motors, as they electronically create the other 2 phases with the required 120 degree separation.

The only possible way that I can see of having an out-of-the-box induction motor with 8000 RPM is if you are referring to an airport premises power which is 400 Hz.This would be a 6 pole motor.

Are you sure you mean 8 Thousand RPM?, not 8 hundred?

An 8 pole 60Hz motor would be about right, allowing for normal slip of rotor.(12%)

Why not use a stepper motor or servo instead?