CAD CAM EDM DRO - Yahoo Group Archive

L298 Commutation Diodes (was Re: Chopper circuit)

Posted by waynegramlich
on 2002-04-04 21:36:16 UTC
--- In CAD_CAM_EDM_DRO@y..., "mariss92705" <mariss92705@y...> wrote:
> Wayne,
>
> The numbers are based on the assumption the rectifiers will conduct
> about 50% of the time. That being given, Vsat losses are 2A times
2V,
> giving you 4W per pass transistor. Since there are 2 per bridge and
> there are 2 bridges, figure on 16W total.
>
> If the transistors are "on" for a 50% duty cycle, figure the
> transistor losses at 8W (50% of 16W).
>
> Now figure the diode losses as 2A times 1V, giving 2W per diode.
> Since 4 diodes will be "on" at any given time, you get 8W. Figuring
a
> 50% duty cycle, this yeilds 4W for the diodes.
>
> Add up the contributions of each and you get 8W plus 4W for a total
> of 12W conduction losses.
>
> Switching losses can be figured at 46V times 2A, giving 92W for
> perhaps 1 microsecond. At 25 kHz there is one "edge" every 20 uS.
The
> average dissipation becomes 92W times 1uS / 20uS, or 4.6W per
bridge.
> There are 2 bridges for a total of 9.2W of switching losses.
>
> Now total up switching and conduction losses of 9.2W and 12W to get
a
> total package dissipation of 21.2W.
>
> The diodes contribute only 4W or 19% to the total. Were you to get
> diodes with a Vf of .5V @ 2A (nearly impossible), you would save
only
> 2W or 9% of the total dissipation. Furthermore this dissipation is
> outside the bridge IC and can do nothing to relive its heat burden.

Mariss:

Now that you explain it, it seems so crystal clear; but when it
was presented as a terse equation, I couldn't figure it out.

At 4W for the 8 diodes in the two bridges, that is only .5W per
diode, which should be not stress the diodes much at all.
This is good because I can't easily add a heat sink to the
diodes, whereas the L298 has a nice mounting hole for a heat
sink.

> That is the reason I said not to sweat the diodes very much.
>
> Mariss

The reason why not to sweat the diodes is now clear.

The message above is going to join a bunch of other
messages written by you in my motion control folder.

Thanks,

-Wayne

Discussion Thread

Steve Blackmore 2002-03-27 16:57:25 UTC Chopper circuit pfrederick1 2002-03-28 05:41:01 UTC Re: Chopper circuit Vajk Fekete 2002-03-28 06:19:45 UTC Re: [CAD_CAM_EDM_DRO] Re: Chopper circuit stephen_stallings 2002-03-28 12:05:30 UTC Re: Chopper circuit pfrederick1 2002-03-28 12:25:46 UTC Re: Chopper circuit Tony Jeffree 2002-03-28 13:46:18 UTC Re: Chopper circuit Steve Blackmore 2002-03-28 20:38:28 UTC Re: [CAD_CAM_EDM_DRO] Re: Chopper circuit RichD. 2002-03-28 21:12:41 UTC Re: [CAD_CAM_EDM_DRO] Re: Chopper circuit Steve Blackmore 2002-03-29 03:34:08 UTC Re: [CAD_CAM_EDM_DRO] Re: Chopper circuit Steve Blackmore 2002-04-02 12:07:07 UTC Chopper circuit waynegramlich 2002-04-02 20:02:49 UTC Re: Chopper circuit Steve Blackmore 2002-04-03 11:16:21 UTC Re: [CAD_CAM_EDM_DRO] Re: Chopper circuit paul_alz 2002-04-03 15:46:51 UTC Re: Chopper circuit andrewyslee 2002-04-03 15:54:29 UTC safety Chris L 2002-04-03 16:28:58 UTC Re: [CAD_CAM_EDM_DRO] safety waynegramlich 2002-04-03 16:36:57 UTC Re: Chopper circuit waynegramlich 2002-04-03 16:41:50 UTC Re: Chopper circuit JanRwl@A... 2002-04-03 16:46:35 UTC Re: [CAD_CAM_EDM_DRO] safety andrewyslee 2002-04-03 17:45:36 UTC Re: safety JanRwl@A... 2002-04-03 18:31:59 UTC Re: [CAD_CAM_EDM_DRO] Re: safety mariss92705 2002-04-03 19:01:55 UTC Re: Chopper circuit Raymond Heckert 2002-04-03 23:16:06 UTC Re: [CAD_CAM_EDM_DRO] safety waynegramlich 2002-04-04 09:37:54 UTC L298 Commutation Diodes (was Re: Chopper circuit) paul_alz 2002-04-04 15:55:03 UTC Re: Chopper circuit mariss92705 2002-04-04 16:51:05 UTC L298 Commutation Diodes (was Re: Chopper circuit) Raymond Heckert 2002-04-04 19:35:10 UTC Re: [CAD_CAM_EDM_DRO] Re: Chopper circuit dave_ace_me 2002-04-04 19:50:29 UTC Re: Chopper circuit dave_ace_me 2002-04-04 19:55:25 UTC OT irfranview ( was Re: Chopper circuit waynegramlich 2002-04-04 21:18:39 UTC Re: Chopper circuit waynegramlich 2002-04-04 21:36:16 UTC L298 Commutation Diodes (was Re: Chopper circuit) paul_alz 2002-04-04 23:49:13 UTC Re: Chopper circuit dave_ace_me 2002-04-05 05:39:10 UTC Re: Chopper circuit paul_alz 2002-04-06 01:04:04 UTC Re: Chopper circuit ballendo 2002-04-06 06:47:08 UTC Re: Chopper circuit JanRwl@A... 2002-04-06 13:21:47 UTC Re: [CAD_CAM_EDM_DRO] Re: Chopper circuit mariss92705 2002-04-06 14:06:59 UTC Re: Chopper circuit Steve Blackmore 2002-04-06 16:50:32 UTC [CAD_CAM_EDM_DRO] Was Chopper circuit - Now ver 3.2 paul_alz 2002-04-07 03:19:03 UTC Re: Was Chopper circuit - Now ver 3.2 Steve Blackmore 2002-04-07 05:00:04 UTC Re: [CAD_CAM_EDM_DRO] Re: Was Chopper circuit - Now ver 3.2 paul_alz 2002-04-07 09:47:58 UTC Re: Was Chopper circuit - Now ver 3.2 n4onl 2002-04-07 10:20:22 UTC Re: Was Chopper circuit - Now ver 3.2 paul_alz 2002-04-07 12:31:11 UTC Re: Was Chopper circuit - Now ver 3.2 Larry Edington 2002-04-07 13:26:08 UTC Re: [CAD_CAM_EDM_DRO] Re: Was Chopper circuit - Now ver 3.2 n4onl 2002-04-07 15:53:03 UTC Re: Was Chopper circuit - Now ver 3.2 waynegramlich 2002-04-07 17:21:57 UTC Re: Was Chopper circuit - Now ver 3.2 Steve Blackmore 2002-04-07 18:05:36 UTC Re: [CAD_CAM_EDM_DRO] Re: Was Chopper circuit - Now ver 3.2 mariss92705 2002-04-07 18:07:59 UTC Re: Was Chopper circuit - Now ver 3.2 Tim Goldstein 2002-04-07 19:04:37 UTC RE: [CAD_CAM_EDM_DRO] Re: Was Chopper circuit - Now ver 3.2 mariss92705 2002-04-07 19:43:07 UTC Re: Was Chopper circuit - Now ver 3.2 mariss92705 2002-04-07 20:00:17 UTC Re: Was Chopper circuit - Now ver 3.2 RichD 2002-04-07 20:08:58 UTC Re: [CAD_CAM_EDM_DRO] Re: Was Chopper circuit - Now ver 3.2 marble here 2002-04-07 20:40:37 UTC Re: [CAD_CAM_EDM_DRO] Re: Was Chopper circuit - Now ver 3.2 Tim Goldstein 2002-04-07 20:54:18 UTC RE: [CAD_CAM_EDM_DRO] Re: Was Chopper circuit - Now ver 3.2 marble here 2002-04-07 21:05:47 UTC Re: [CAD_CAM_EDM_DRO] Re: Was Chopper circuit - Now ver 3.2 marble here 2002-04-07 21:09:10 UTC RE: [CAD_CAM_EDM_DRO] Re: Was Chopper circuit - Now ver 3.2 Jon Elson 2002-04-07 22:13:44 UTC Re: [CAD_CAM_EDM_DRO] Re: Was Chopper circuit - Now ver 3.2 Doug Fortune 2002-04-07 22:33:53 UTC Re: [CAD_CAM_EDM_DRO] Re: Was Chopper circuit - Now ver 3.2 Paul Weber 2002-04-07 23:28:57 UTC Re: [CAD_CAM_EDM_DRO] Re: Was Chopper circuit - Now ver 3.2 Tony Jeffree 2002-04-07 23:42:39 UTC Re: Was Chopper circuit - Now ver 3.2 Steve Blackmore 2002-04-08 00:45:16 UTC Re: [CAD_CAM_EDM_DRO] Re: Was Chopper circuit - Now ver 3.2 mariss92705 2002-04-08 00:49:48 UTC Re: Was Chopper circuit - Now ver 3.2 mariss92705 2002-04-08 01:01:35 UTC Re: Was Chopper circuit - Now ver 3.2 paul_alz 2002-04-08 01:13:38 UTC Re: Was Chopper circuit - Now ver 3.2 Steve Blackmore 2002-04-08 01:17:45 UTC Re: [CAD_CAM_EDM_DRO] Re: Was Chopper circuit - Now ver 3.2 paul_alz 2002-04-08 02:05:30 UTC Re: Was Chopper circuit - Now ver 3.2 Tony Jeffree 2002-04-08 02:14:33 UTC Re: Was Chopper circuit - Now ver 3.2 paul_alz 2002-04-08 02:29:31 UTC Re: Was Chopper circuit - Now ver 3.2 paul_alz 2002-04-08 02:40:50 UTC Re: Was Chopper circuit - Now ver 3.2 Paul R. Hvidston 2002-04-08 07:41:15 UTC Re: [CAD_CAM_EDM_DRO] Re: Was Chopper circuit - Now ver 3.2 cadcamcenter 2002-04-08 08:40:22 UTC Re: Was Chopper circuit - Now ver 3.2 mariss92705 2002-04-08 21:37:12 UTC Re: Was Chopper circuit - Now ver 3.2 Jon Elson 2002-04-08 21:57:48 UTC Re: [CAD_CAM_EDM_DRO] Re: Was Chopper circuit - Now ver 3.2 Larry Edington 2002-04-08 22:17:11 UTC Re: [CAD_CAM_EDM_DRO] Re: Was Chopper circuit - Now ver 3.2 Larry Edington 2002-04-08 22:28:06 UTC Re: [CAD_CAM_EDM_DRO] Re: Was Chopper circuit - Now ver 3.2 Larry Edington 2002-04-08 22:36:50 UTC Re: [CAD_CAM_EDM_DRO] Re: Was Chopper circuit - Now ver 3.2 RichD 2002-04-08 22:51:44 UTC Re: [CAD_CAM_EDM_DRO] Re: Was Chopper circuit - Now ver 3.2 mariss92705 2002-04-09 00:08:36 UTC Re: Was Chopper circuit - Now ver 3.2 paul_alz 2002-04-09 01:01:27 UTC Re: Was Chopper circuit - Now ver 3.2 Jon Elson 2002-04-09 10:14:11 UTC Re: [CAD_CAM_EDM_DRO] Re: Was Chopper circuit - Now ver 3.2 Jon Elson 2002-04-09 10:36:24 UTC Re: [CAD_CAM_EDM_DRO] Re: Was Chopper circuit - Now ver 3.2 mariss92705 2002-04-09 11:54:39 UTC Re: Was Chopper circuit - Now ver 3.2 Jon Elson 2002-04-09 22:44:20 UTC Re: [CAD_CAM_EDM_DRO] Re: Was Chopper circuit - Now ver 3.2 Steve Blackmore 2002-04-10 04:01:07 UTC Re: Was Chopper circuit - Ver 3.2 Web page up ballendo 2002-04-13 05:31:51 UTC Re: safety andrewyslee 2002-04-13 16:01:35 UTC Re: safety wanliker@a... 2002-04-13 23:27:38 UTC Re: [CAD_CAM_EDM_DRO] Re: safety ballendo 2002-04-14 01:06:45 UTC Re: Was Chopper circuit - Now ver 3.2 ballendo 2002-04-14 03:44:04 UTC pcb sources was Re: Was Chopper circuit - Now ver 3.2 dave_ace_me 2002-04-14 06:31:41 UTC pcb sources was Re: Was Chopper circuit - Now ver 3.2 JanRwl@A... 2002-04-14 16:51:19 UTC Re: [CAD_CAM_EDM_DRO] Re: safety andrewyslee 2002-04-14 17:52:15 UTC safety - pcb dust hazard mariss92705 2002-04-14 18:06:00 UTC Re: safety - pcb dust hazard mariss92705 2002-04-14 18:10:08 UTC Re: safety andrewyslee 2002-04-14 18:39:49 UTC Re: safety - pcb dust hazard Sven Peter 2002-04-14 18:53:27 UTC Re: [CAD_CAM_EDM_DRO] safety - pcb dust hazard marble_h 2002-04-14 19:27:38 UTC Re: safety - pcb dust hazard J.Critchfield 2002-04-14 20:09:15 UTC Re: [CAD_CAM_EDM_DRO] Re: safety - pcb dust hazard JanRwl@A... 2002-04-15 00:01:23 UTC Re: [CAD_CAM_EDM_DRO] Re: safety JanRwl@A... 2002-04-15 00:05:02 UTC Re: [CAD_CAM_EDM_DRO] Re: safety dave_ace_me 2002-04-15 04:05:04 UTC Re: safety - pcb dust hazard andrewyslee 2002-04-15 17:45:42 UTC Re: safety - pcb dust hazard andrewyslee 2002-04-15 18:17:13 UTC Re: safety - pcb dust hazard ballendo 2002-04-16 13:58:59 UTC Re: safety - pcb dust hazard Raymond Heckert 2002-04-16 16:01:33 UTC Re: [CAD_CAM_EDM_DRO] Re: safety ballendo 2002-04-16 16:44:40 UTC Re: safety - pcb dust hazard ballendo 2002-04-17 01:23:05 UTC What to do in an estop ?!? was Re: safety mariss92705 2002-04-17 03:03:29 UTC Re: safety Sven Peter 2002-04-17 06:49:42 UTC Re: [CAD_CAM_EDM_DRO] Re: safety mariss92705 2002-04-17 07:23:55 UTC Re: safety - pcb dust hazard dave_ace_me 2002-04-17 10:02:12 UTC Re: safety - pcb dust hazard mariss92705 2002-04-17 10:53:38 UTC Re: safety - pcb dust hazard dave_ace_me 2002-04-17 20:07:33 UTC Re: safety - pcb dust hazard askforum 2002-04-17 20:07:55 UTC Re: safety - pcb dust hazard JanRwl@A... 2002-04-17 20:30:05 UTC Re: [CAD_CAM_EDM_DRO] Re: safety mariss92705 2002-04-17 22:23:42 UTC Re: safety - pcb dust hazard Ward 2002-04-18 01:14:10 UTC RE: [CAD_CAM_EDM_DRO] Re: safety - pcb dust hazard batwings@i... 2002-04-18 04:30:08 UTC RE: [CAD_CAM_EDM_DRO] Re: safety - pcb dust hazard dave_ace_me 2002-04-18 04:57:56 UTC Re: safety - pcb dust hazard steveggca 2002-04-18 05:00:12 UTC What to do in an estop ?!? was Re: safety Jon Elson 2002-04-18 05:42:20 UTC Re: [CAD_CAM_EDM_DRO] Re: safety Raymond Heckert 2002-04-18 09:51:38 UTC Re: [CAD_CAM_EDM_DRO] What to do in an estop ?!? was Re: safety Jon Elson 2002-04-18 10:59:03 UTC Re: [CAD_CAM_EDM_DRO] What to do in an estop ?!? was Re: safety mariss92705 2002-04-18 11:45:34 UTC Re: safety Jon Elson 2002-04-18 23:06:48 UTC Re: [CAD_CAM_EDM_DRO] Re: safety Hugh Prescott 2002-04-19 01:28:37 UTC Re: [CAD_CAM_EDM_DRO] Re: safety - pcb dust hazard ballendo 2002-04-19 06:16:34 UTC OT Re: safety - pcb dust hazard