[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: (ET) Designing controllers

David,
The thing about electronics is that, today, it's such an immense field that EE's usually find an area they like and specialize in it. I get a slew of trade mags but I skip over half the stuff that doesn't pertain to my interests. ( being retired I can do that now!). I've done some work in magnetics so controllers and inverters aren't totally new to me, getting up to speed shouldn't be that tough. Shoot thru can be a big problem, that's where you have opposing 'H' bridge paths on at the same time. I'm using the HIP4081A which is a good chip to prevent that. What happens often is that one side doesn't completely settle before the other side gets energized. Another problem is capacitance loading where the high side charge pump faces excessive capacitance from the MOSFETs and turn on time is too slow. The longer it takes for a MOSFET to turn on the more energy it absorbs so high side charge pumps have to be carefully designed. If done right things like inductive loading don't overheat the MOSFETs. We'll see what happens when I build a couple of prototypes and how much trouble I run into driving these motors but at 1.2 HP I think I should be able to overcome most of the problems. Efficiencies in inverters and controllers depends a lot on how fast a semiconductor reaches maximum potential (Slew rate) and the RDSon of the device. You want a fast rise time and a low RDSon. Also inverter technology adds the magnetics, how low the impedance of the inductor is relates to efficiency because it's like adding a resistor in a DC circuit. So when we talk about PWM we also have to talk abut the frequency of the circuit in inductor work because inductive reactance is a product of frequency. The higher the frequency the smaller the inductor, that's why SMPS has made such an impact on power supplies in the last several years, we've gotten rid of the clunky power transformer, it has been replaced by a small inductor. The problem is that inductor compositions can be dizzying! Manufacturers know this and their engineers are accessible to help. Something else has come along it's called Berkley SPICE. For those of you who don't know, SPICE is a mathematical simulation for electronic circuits. Companies like Linear and Intersil, who makes the HIP4081A have now added SPICE to their sites and you can download the programs for free that let you simulate the venders chips... very accurately. Heat, shoot thru, inductive loads, PWM frequencies, etc. get started in a simulation program. Blown chips become a minimum and when that happens you get to run an email out to the vender and have an engineer give you pointers. Hard to beat! 

Best,
Rob
-----Original Message----- From: elec-trak-request cosmos phy tufts edu 
Sent: Tuesday, January 01, 2013 6:00 AM
To: elec-trak cosmos phy tufts edu
Subject: Elec-trak Digest, Vol 11, Issue 1

Send Elec-trak mailing list submissions to
elec-trak cosmos phy tufts edu

To subscribe or unsubscribe via the World Wide Web, visit
https://cosmos.phy.tufts.edu/mailman/listinfo.cgi/elec-trak
or, via email, send a message with subject or body 'help' to
elec-trak-request cosmos phy tufts edu

You can reach the person managing the list at
elec-trak-owner cosmos phy tufts edu

When replying, please edit your Subject line so it is more specific
than "Re: Contents of Elec-trak digest..."


Today's Topics:

  1. Re:  Controllers and inverters (David Roden)
  2. Re:  Controllers and inverters (David Roden)
  3.  40th Elec-Trak Anniversary DVD (George Beckett)


----------------------------------------------------------------------

Message: 1
Date: Mon, 31 Dec 2012 16:46:22 -0500
From: "David Roden" <etpost drmm net>
To: elec-trak cosmos phy tufts edu
Subject: Re: (ET) Controllers and inverters
Message-ID: <50E1C15E 5878 9619B6 etpost drmm net>
Content-Type: text/plain; charset=US-ASCII

On 31 Dec 2012 at 15:29, Robert Troll wrote:
And the Curtis 1204 is a PWM controller. I can only assume that the Alltrax is 
as well.


Does anyone know of any DC motor controllers that aren't pulse width
modulated?  Other than simple rectactor / contactor /. resistor based ones,
that is.

Though I'm a layman, I understand reasonably well how a PWM controller
works.  Can you briefly summarize the principle of operation behind these
non-PWM controllers?

Thanks.


David Roden - Akron, Ohio, USA

= = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =
Note: mail sent to the "etpost" address will not reach me.  To send
me a private message, please use the address shown at the bottom
of this page : http://www.evdl.org/help/
= = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =






------------------------------

Message: 2
Date: Mon, 31 Dec 2012 16:46:22 -0500
From: "David Roden" <etpost drmm net>
To: <elec-trak cosmos phy tufts edu>
Subject: Re: (ET) Controllers and inverters
Message-ID: <50E1C15E 19931 961AD8 etpost drmm net>
Content-Type: text/plain; charset=US-ASCII

On 31 Dec 2012 at 9:48, Robert wrote:


I'm sure the Alltrax is a wonderful controller and for those without
the ends and the ability to design those circuits it's a great way to
go.


My hat's off to anybody who can and does design his own controller!  From
what I can tell, it's far from trivial.  And of course you get exactly what
you want in a controller.

That said, I know a couple of people with ample EE / EV design chops who
have chosen to buy instead of building their controllers themselves.  From
what they tell me, having had previous experience designing and debugging
controllers, they decided it would actually be cheaper to buy than to build
from scratch. Also, they had a working EV in much less time.


David Roden - Akron, Ohio, USA

= = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =
Note: mail sent to the "etpost" address will not reach me.  To send
me a private message, please use the address shown at the bottom
of this page : http://www.evdl.org/help/
= = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =






------------------------------

Message: 3
Date: Tue, 1 Jan 2013 00:14:51 -0500
From: George Beckett <irishbeckett hotmail com>
To: "elec-trak cosmos phy tufts edu" <elec-trak cosmos phy tufts edu>
Subject: (ET) 40th Elec-Trak Anniversary DVD
Message-ID: <SNT002-W18869AC8AC372FF63C9018FCC230 phx gbl>
Content-Type: text/plain; charset="iso-8859-1"
Finally got the videos from the videographer at the 40th Elec-Trak Anniversary Gathering and Elec-Trak Show and Swap Meet in Vermont this past summer. Also recently was finally able to get them burned to a DVD. I also have some other DVD's available as well, $10.00 each plus shipping, let me know if you would like any of them by sending me an email with your address to geo myelec-traks com. All proceeds go to 
cover the reunion expenses.

1.) Elec-Trak Movie (8 mins, 40 secs.)
2.)
Elec-Trak 50 sec. Commercial (No sound- had voice overs by the local TV stations) 
3.)
Early G.E. Elec-Trak Prototypes from 35MM Slides (Approx. 140 slides digitized 
on DVD from the "Skip Smith" Collection). These are really neat and came 
out
great!
4.) 2012 Elec-Trak Show & Swap Meet and 40th Anniversary Gathering
(Includes many photographs and videos of the event.)

Send me a check or money order after you receive them in the mail.
Happy New Year all!

In Him,

George Beckett
Evermore Farm
Lyles, TN

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://cosmos.phy.tufts.edu/mhonarc/elec-trak/attachments/20130101/11fc2e4f/attachment.html> 

------------------------------

_______________________________________________
Elec-trak mailing list
Elec-trak cosmos phy tufts edu
https://cosmos.phy.tufts.edu/mailman/listinfo.cgi/elec-trak


End of Elec-trak Digest, Vol 11, Issue 1
****************************************