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Anonymous Poster #1

Pulse Width Modulation

07/30/2013 3:58 PM

PWM technology use 6 or 12 pulses to generate variable frequencies and hence control the speed of Induction Motor.

Which is more efficient 6 or 12 pulses and why?
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Anonymous Poster #2
#1

Re: Pulse Width Modulation

07/30/2013 4:14 PM

Why not 18, or 24, or 32?
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lyn
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Join Date: Oct 2008
Posts: 42355
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#2

Re: Pulse Width Modulation

07/30/2013 4:44 PM

More pulses=more precise control=more efficient operation.

Why don't you do some research on the subject, whoever you are?

Pulse Width Modulation (PWM) Technology - Digikey

Pulse-width modulation - Wikipedia, the free encyclopedia
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RAMConsult
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Engineering Fields - Power Engineering - New Member

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#3

Re: Pulse Width Modulation

07/30/2013 5:40 PM

Nice homework/interview question. What was your answer and why?

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JRaef
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United States - Member - New Member Engineering Fields - Power Engineering - New Member

Join Date: Sep 2006
Location: California, USA, where the Godless live next door to God.
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#4

Re: Pulse Width Modulation

07/30/2013 5:44 PM

6 or 12 pulse has to to with the rectification, not the PWM output. Your professor is trying to trip you up...

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Anonymous Poster #1
#5
In reply to #4

Re: Pulse Width Modulation

08/01/2013 6:21 PM

???? = !!!!!!!

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electricalexpert65
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Join Date: Oct 2009
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#6

Re: Pulse Width Modulation

08/04/2013 10:36 AM

It is not the question of efficiency. Between 6-pulse & 12-pulse VFDs, the 5th & 7th Harmonics generated in the VFD would get cancelled in a 12-pulse VFD - PROVIDED, the two 6-pulse rectifiers in the VFD are fed from a star secondary winding & a delta secondary winding respectively of a three winding transformer. If the above arrangement is not done, there is no point in going for a 12 pulse rectifier.
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Users who posted comments:

Anonymous Poster (2); electricalexpert65 (1); JRaef (1); lyn (1); RAMConsult (1)

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