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Miguel Mendoza

Going Green: The Trend Toward High-Efficiency Brushless DC Motors

Miguel Mendoza
RedDerek
RedDerek
7/2/2013 6:23:52 PM
User Rank
Master
Re: BDCM and electric vehicles
Nice videos. Now to see how to apply this in retro-fitting an old car with electric motors.

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Ranasinghe
Ranasinghe
6/29/2013 7:46:11 AM
User Rank
Master
Re: BDCM and electric vehicles
Interesting post Miguel,

Thanks for the all the links with the utube video it was very clear. 

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Miguel Mendoza
Miguel Mendoza
6/26/2013 7:05:48 PM
User Rank
Blogger
Re: BDCM and electric vehicles
Hello, 

You are all welcome to watch the our demonstration videos.

Evolution: http://www.youtube.com/watch?v=47IdBfa4ALo

Demo: http://www.youtube.com/watch?v=PEf0Y9un7Ik

Please visit us at www.micrel.com

Regards,

Miguel Mendoza

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Miguel Mendoza
Miguel Mendoza
6/26/2013 6:31:35 PM
User Rank
Blogger
Re: BDCM and electric vehicles
Hello,

Thank you for your kind comments regarding the article.

1)      For combustion engines, fuel economy is a key motivator to adopt BLDC motors.   For the same power ratings, the BLDC motors are 55% the size compared to AC motor and 75% of the size of brushed DC motors.   There are about 22 motors in a high end vehicle, any reduction in weight helps with fuel economy.

2)      I have not personally seen our customer use "dynamic braking" with BLDC motors, but my experience is mainly focused on power tools, automotive body controls and household appliances.  Many years ago, I did get a chance to drive a trolley car from 1910's that had dynamic braking.  Just like today's hybrids, dynamic braking is a good way to smoothly slow down trolley but I had to use the hand brake to completely stop.    

3)      Hybrid vehicles use a blend of regenerative braking and friction braking.   When the brake is applied; the electric motor decelerates the vehicle and recharges the car bank batteries, friction brakes is applied to stop the vehicle completely.  

4)      I am not expert on VFD motors, it's difficult to compare without further study on my part, but I do know that our customers are migrating towards BLDC motors due to low maintenance, longer life and power efficiency.    We are just trying to make easy for our customers to retool for BLDC motors.   It's my opinion that BLDC can replace AC motors, real question are customers willing to retool.      

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D Feucht
D Feucht
6/26/2013 3:47:18 PM
User Rank
Blogger
Re: BDCM and electric vehicles
It is a good idea to write an article occasionally on permanent-magnet synchronous (PMS) motors because they really are the best solution to a wide range of motion generation problems. As for PMS-controller ICs, the phase control by sensing the induced winding voltage was refined in the early 1990s to where the scheme Dan Simon and I published in the IEEE Transactions on Industrial Electronics, June 2004 (Vol. 51, No. 3, ITIED6), titled "Synchronous Motor Phase Control by Vector Addition of Induced Winding Voltages" (p. 537, ff) uses one LM3900 quad comparator and less than a dozen resistors. Since then an improved variation is found in my notebook shelf, waiting for someone to apply it. (See innovatia.com under motion control.)

The published scheme, implemented with a McCord-Winn TEXTRON PMS motor for automotive applications, would have enough phase information from the initial vibration of the shaft from an applied phase to become phase-controlled before any substantial motion would have occurred. I would be pleased to have Micrel take a look at it. It is better in a number of respects than the scheme Allan Plunkett devised for an earlier Micrel part, though Allan's scheme at the time was a good one. And it is free of patent entanglements, though that does not mean there is not additional useful and detailed implementation information.

The same could be achieved by an IC for induction motors, which are better (cheaper) for some applications. They too can be controlled (though it is more difficult) and can do all that a PMS motor can do, though with performance limited by the ability to accurately estimate rotor resistance.

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eafpres1
eafpres1
6/26/2013 3:27:40 PM
User Rank
Blogger
BDCM and electric vehicles
Hi Miguel--nice article.  Can you comment on a few items:

1) For transportation (cars, trains, buses, etc.) do BDCMs have advantages?

2) Presumably an advantage, but requiring more complex control is how you can employ braking in DC motors.  Do you see that in practice?

3) Related to (2), I'm guessing regenerative braking for things like hybrid vehicles would also use BDCMs and a control circuit?

4) Regarding the related blog on Variable Frequency Drives for AC motors and whether they are really efficient or not, do you view BDCM as preferable to VFD and if  so are there "best" ranges for BDCMs?

Thanks again for the article.

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