Alexander Wolfe
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Efficieny rules
Alexander Wolfe   8/15/2011 11:21:10 AM
This story is very timely given the increased interest, and deployment of, energy efficient motors. I'll be writing about that, and about the results of a reader survey we did on energy efficient motors and drives, in the September issue of Design News.

TJ McDermott
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TJ McDermott   8/15/2011 12:16:24 PM
This is exciting!  When can we expect to see these new motors (espeically in the smaller frames)?

Greg Stirling
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Synchronous Reluctance Motor Breakthrough
Greg Stirling   8/15/2011 2:31:37 PM
Congratulations, this is a great idea.  You guys did a great job. We can always use a little more efficiency, and this will pay off big time in large scale, continuosly running operations...

User Rank
How can this be said to be anything to do with PM motors?
ChrisP   8/17/2011 12:51:54 AM
It does not have any magnets in it at all and no brush gear.  Maybe they meant stepper motor.

What we need are smaller motors in this technology that are quiet and efficient.

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What is the breakthrough?
rosek   8/17/2011 9:37:57 AM
Is the breakthrough the gains in efficiency when compared to squirrel cage designs?  SRM's have been around for quite a while and the main problem associated with this technology has always been in the drive electronics - it is difficult to manage this type of motor without sophisicated controls. 

William K.
User Rank
Synchronous induction motors?
William K.   8/17/2011 12:31:05 PM
An induction motor can only run below synchronous speed because the rotor field is generated by the slip speed between the stator and the rotor. The power used to create the rotor magnetic field is the loss mentioned by others. The strength of the induction motor is that as the load increases the slip also increases, which increases the current and magnetic field in the rotor. IT works well, but it uses more power than the synchronous motor. ON the other side, the synchronous motor is driven by the rotating magnetic field dragging the rotor magnets around. The problem with an ordinary synchronous motor is that when the load increases a point is reached where it falls out of synchronization and then stalls. This is great if you seek to have a very reliable means to limit torque, otherwise it is a problem. A hybrid motor that will continue to deliver torque as the load increases would be very handy, and it could probably be easier to control the speed with a VF drive. Also, it might wind up having a greater efficiency, which is a definite goal.

Is it possible to provide a more detailed description about how it provides this new function?

N. Christopher Perry
User Rank
Torque Ripple
N. Christopher Perry   9/9/2011 10:25:00 AM
My experience with SynRM are that, by their nature, they generate significantly more torque ripple than an induction motor.  Has this been remedied or did the author simply fail to mention it as a factor to be considered in selecting a SynRM for an application?

N. Christopher Perry
User Rank
Re: What is the breakthrough?
N. Christopher Perry   9/9/2011 10:31:32 AM
You do need a motor dive to operate a SynRM, but that type of drive is significantly less complex than a VVVF drive used for varying induction motor speed.  They're not much more complex than 'soft-start' controllers.  Given the dramatic reduction in the costs for all types of motor controls over the past 20 years, the cost of the drive electronics for a SynRM are going to be modest in all but the most cost sensitive applications.  Additionally, the operating cost savings are likely to largely offset the cost of any drive electronics.

User Rank
all the answers
lcelectro   1/15/2012 5:54:12 PM
You can find all the answers at the ABB Review at


The most important answer is hidden behind these words:

Finally, rare earth materials
for permanent magnets are relatively expensive
and may be in limited supply for
some markets, due to geographic concentration
of the common raw materials

This means: China is the only producer of rare earth magnets, (all other rare earth minig sites closed down) and now we can kiss them goodbye.

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