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Induction Motor

08/26/2011 6:03 AM

how can i control speed of induction motor by varying frequency using an inverter

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Guru
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#1

Re: Induction Motor

08/26/2011 8:03 AM

The answer is in the question.

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Guru
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#2

Re: Induction Motor

08/26/2011 12:00 PM

An "inverter" all by itself technically will not do it. You need one capable of altering the votlage and frequency together. When you have that, you have what is called a "Variable Frequency Drive" or VFD. Some p\eople still call tyhem "inverters" or "inverter drives", but technically that term is too generic; an inverter can be a solar power inverter, a DC to AC inverter etc. etc. Also, in a VFD only PART of the unit is an inverter, the back end. A VFD consists of a CONVERTER that converts the AC line to DC, a DC Link that smooths out the DC ripple and allows braking, a Control System that does the complex control algorithms to make the magic happen and connect to the real world and then the Inverter section that re-fires the DC pulses into pseudo AC for the motor.

So if you went down to the store and asked for an "inverter", you will not likely get what you need but if you ask for a VFD, you will, and it will have an "inverter" inside of it.

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#3
In reply to #2

Re: Induction Motor

08/27/2011 3:46 AM

Actually i have a dc input of 48 volts so i dont think i require a VFD containing a rectifier and dc link, so remaining is only the inverter, so how can i do it?

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Anonymous Poster #1
#4
In reply to #3

Re: Induction Motor

08/27/2011 5:17 PM

48 volt DC means you can converted to 48 AC by inverter. then you need step up transformer to increase the voltage according to your motor Voltage rating.

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Guru
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#5

Re: Induction Motor

08/27/2011 11:44 PM

Your inverter still needs to be able to vary the voltage and frequency output together in a coordinated fashion, one that maintains the V/Hz ratio of the motor's original design. If your inverter was not designed to do this, you cannot make it do this. So you buy a VFD.

By the way, 48VDC is going to be capable of powering a 34VAC motor. Where did you find a 34VAC induction motor?

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