Re: DC Motor Control - Heat Issue

From: John Popelish (jpopelish_at_rica.net)
Date: 01/18/05 

Date: Tue, 18 Jan 2005 17:03:32 -0500

Andrew wrote:
>
> All,
>
> I do have a schematic of the current driver. The details of this 4
> switch H-Bridge type driver are located here, as well as two links (at
> the bottom) to the two pages of the schematic:
>
> http://www.robot-electronics.co.uk/htm/md03tech.htm
>
> The application of this design actually is intended for low level
> production at some point, and cost (and availability) is a driving
> factor.
>
> The most recent problem I am seeing concerning a choke is that they are
> expensive (and large/heavy) for high current applications. Since I am
> running 6A per motor, for a 12A continuous output (per driver), 20A
> (maximum allowable) peak, the DC chokes appear to be in the $60 range,
> which is more than half the cost of the driver itself. I would need
> two of these chokes, and four smaller ones for four other motor
> outputs, costing roughly $30 each, or 1/3 the cost of the driver each.
>
> I think, with these costs, I may need to just investigate new drivers.
> Finding inductors able to handle these high currents doesn't seem to be
> the most cost effective solution after all.
>
> Also, I am getting mixed input as to whether or not to use a higher PWM
> frequency or a lower one. It seems that I should be using a higher
> frequency, but some of you have indicated a lower frequency? This is a
> little confusing.
>
> Does anyone have any reccomendations of companies offering inductors in
> the 470uH range that can handle roughly 15A+ continuous current? Renco
> has these parts, however, they are $60+. I am looking for a cheap
> alternative, in order to test a DC choke/LC filter. In the meantime, I
> will look into some new, higher frequency drivers.
> Thanks for all your help guys.
>
> Sincerely,
> Andrew Czop

Have you looked at any of the large size drum core inductors? Renco
pioneered them, years ago, but they are made by many companies, today,
and many deliver at prices way below Renco.

Look at the size 13 inductors at the bottom of this catalog.
http://www.rhombus-ind.com/magcat/drum2.pdf
There is a 380 uHy rated for 22.4 amps, continuous. 

-- 
John Popelish

Relevant Pages

  • Re: Coach firms in the general vacinity of Gilwell
    ... In the past we've hired a coach and driver for the entire week, ... something which has cost us an arm and a leg. ... Akela 1st Marple Bradshaw Cubshttp://1stmarplebradshawcubs.org.uk ...
    (uk.rec.scouting)
  • Re: The validity of PPC notices/tickets - discuss
    ... driver, and the significance of them understood, then he has accepted ... that to enter and park on the land will cost him a fee. ... However when you get into areas like parking not within the marked ... Also note the judge does not like the idea that people are advised to ...
    (uk.legal)
  • Re: [GIT PATCH] more Driver core patches for 2.6.19
    ... > So let's come out and ban binary modules, ... claiming that loading a binary-only driver is a GPL violation. ... chip development projects get away with shifting some of the real cost ... totally-closed, one-off, buggy vendor driver to a GPL'ed driver in the ...
    (Linux-Kernel)
  • Re: Gotta NIP
    ... If the driver doesn't want to take the offer of admitting guilt early on ... they can have their day in court, see the evidence, engage legal ... You seem to have problems understanding this. ... They don't have to and there is a cost in providing it. ...
    (uk.rec.driving)
  • Re: Mandatory custodials for people who kill others on the roads.
    ... On the cost of RTA's: ... The misery and grief caused by a speeding driver who kills someone is ... happen on roads where the speed limit is 30mph or less. ... If you wanted to say "Mandatory custodials for people who scare others on the roads" you should have said so and started from a different place, now that holes have been poked in your "kill" arguments you can't suddenly shift position to argue about speed and traffic density. ...
    (uk.rec.cycling)