Timeline for MOSFET driver blows out in half-bridge DC motor PWM controller
Current License: CC BY-SA 4.0
25 events
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| Apr 17, 2023 at 1:46 | history | edited | Edin Fifić | CC BY-SA 4.0 |
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| Apr 17, 2023 at 1:20 | comment | added | Edin Fifić | @PStechPaul You're right, I completely forgot to add that, and it was a major thing I was going to suggest. A cold got me bad, it's hard to focus. I am adding them now. | |
| Apr 16, 2023 at 22:09 | comment | added | PStechPaul | One more very important thing is that one or more capacitors are needed across the 24 VDC supply, close to the MOSFETs. I would suggest a 1000 uF low ESR electrolytic, and a 470 nF film capacitor (polypropylene or polyester). Also, routing of grounds and power bus need to be carefully considered, with current approaching 100 A. | |
| Apr 16, 2023 at 20:08 | comment | added | Edin Fifić | @Solmyr999 I have added more to the end of my answer. | |
| Apr 16, 2023 at 20:07 | history | edited | Edin Fifić | CC BY-SA 4.0 |
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| Apr 16, 2023 at 19:18 | comment | added | Solmyr999 | Thank you a lot for all your answers, I really appreciate it ! I will keep delving into all this and follow your advices. I'll stop bothering you now! Have a nice day! | |
| Apr 16, 2023 at 19:06 | history | edited | Edin Fifić | CC BY-SA 4.0 |
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| Apr 16, 2023 at 16:48 | comment | added | Edin Fifić | @Solmyr999 I also have the Art of Electronics. Great book for learning many techniques and subtleties of electronic circuits, but it requires a lot of time to read and digest. If you have more questions, I will try to answer them when I get a chance. You can post questions on StackExchange or we can move to private messaging. Comments are not for extended discussions. | |
| Apr 16, 2023 at 12:31 | comment | added | SamGibson♦ | @Solmyr999 - Hi, I note that you have chosen one of the least bad options and have moved your additional questions from a (non-)answer, into the question. (Therefore your comment above that you have posted an "answer" is now misleading, unfortunately.) Please note that you cannot keep adding questions especially after you have received answers. Your question is in danger of becoming (if not already) a "chameleon question" and may be closed or ignored as just too unclear / "moving goalposts" etc. || Remember that SE is not a forum - ideally a question should not change after being asked. | |
| Apr 16, 2023 at 11:51 | comment | added | greybeard |
if one end of the motor is wired directly to V+ supply line is not what I see in both schematics, the motor having been left out of the picture. And if indeed the motor is driven in low side configuration, something is needed for Vs not to be driven way below GND. Given the low side MOSFET's body diode, its gate drive wouldn't make much of a difference but for recovery. Control of braking is minimal; regenerative braking won't happen without elaborately designing for it.
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| Apr 16, 2023 at 9:47 | comment | added | Solmyr999 | Thank you again for your answer! I've posted an answer to this post with a schematic of what (I think) you are suggesting. I also have some additional questions if you have some time. I am still in the middle of reading the Art of Electronics and more generally learning electronics, so there are many circuit design subtleties and hands-on experience that I don't have. | |
| Apr 16, 2023 at 4:55 | comment | added | Edin Fifić | @Solmyr999 The thing is, even without the upper MOSFET driver, you get regenerative braking because the upper MOSFET body diode will conduct. The only difference with the driver is you will get a lower voltage drop, from around maybe 1V down to less than 0.5V at 100A. What I'm saying is that it's not a huge difference, out of the maximum possible 2400W, you might lose up to about 50W which is not a relatively high loss. I missed the part about regenerative braking. In that case IR2103 can help, but there are integrated circuits which provide even more MOSFET driving current. | |
| Apr 15, 2023 at 16:17 | comment | added | Solmyr999 | I have another question however : my idea by using a half bridge with two MOSFETs was to be able to use regenerative braking to recharge the battery (I want to use this setup on a bike). What you're suggesting is driving only one MOSFET directly from the 555 output, is that correct ? That will make regenerative braking impossible, right ? | |
| Apr 15, 2023 at 16:15 | comment | added | Solmyr999 | Thank you very much for your complete answer ! That explains a lot and gives me many topics I need to look into more in details. Thank you for your solutions! | |
| Apr 15, 2023 at 16:11 | vote | accept | Solmyr999 | ||
| Apr 15, 2023 at 12:22 | history | edited | winny | CC BY-SA 4.0 |
Microsiemens -> microsecond
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| Apr 15, 2023 at 12:07 | comment | added | Edin Fifić | @Solmyr999 I have added more to my answer, should be complete now. Let me know how it goes for you. | |
| Apr 15, 2023 at 12:06 | history | edited | Edin Fifić | CC BY-SA 4.0 |
added much more to the answer, completed the answer
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| Apr 15, 2023 at 9:18 | comment | added | Edin Fifić | @Solmyr999 You actually learn more from such mistakes, and they leave a deeper and more lasting impression. You get to understand circuits and components at a deeper level. If you always had circuits that work without problems, you wouldn't know about the practical issues/problems in the real world. That's why those datasheets have so many details which look like too much at first, but when you start facing issues, those details can be lifesavers. | |
| Apr 15, 2023 at 9:13 | comment | added | Solmyr999 | Ok I understand now. When I think about it, driving such a heavy motor doesn't require a high PWM frequency at all. I should have delved deeper into this while designing my circuit ... but I guess this is good learning experience! | |
| Apr 15, 2023 at 9:08 | comment | added | Edin Fifić | @Solmyr999 At 100Hz, a full cycle will be 10ms, so 10us delays will be only 0.1% of the switching (PWM) frequency, basically nothing. But at 10kHz, a full cycle is 0.1ms or 100us, which makes the 10us delays a full 10% of the cycle, which can significantly affect the circuit. Not only that, when you use a 20% cycle in that case, 10us is HALF of that cycle, and it gets worse as the cycle shortens. | |
| Apr 15, 2023 at 9:01 | comment | added | Edin Fifić | @Solmyr999 The high frequency means shorter duty cycles, which means increased effect all the delays will have on the total circuit. I am preparing the last part of my answer, will let you know when I add it, which will explain why your IC burns out. | |
| Apr 15, 2023 at 8:59 | comment | added | Solmyr999 | When you talk about the driver timing limitations and delays, do you mean that the PWM frequency is too high and the driver doesn't have time to switch on and off properly ? (these are the kind of details I have a hard time understanding) How would the timing limitations cause the driver to blow up ? | |
| Apr 15, 2023 at 8:56 | comment | added | Solmyr999 | Thank you very much for your amazing answer ! When I was looking on the net for how to size my components, I found that tens of kHz PWM frequencies were fine for dc motors, but I guess I must have missed some important details. | |
| Apr 15, 2023 at 8:47 | history | answered | Edin Fifić | CC BY-SA 4.0 |