You are here

Total dead-time of the MOSFETs ???!!

13 posts / 0 new
Last post
ThierryGTLTS
Offline
Last seen: 3 years 9 months ago
Joined: 2017-09-06 14:18
Posts: 116
Total dead-time of the MOSFETs ???!!

Hello,

I noticed that the dead-time of the MOSFETs seems to be composed of 3 parts.

1. HW part DRV8302 (or 01), 10K sets 80nS dead-time, 50µS the min possible + 3nS/1K of resistance.
2. In mc_interface.h #define mcpwm_dead_time_cycles 60, but I ignore the lenght of one cycle, help, please :!:
3. In BLDC Tool or VESC Tool, you can find dead-time compensation, preset to 0.08µS.

So is the total dead-time equivalent to the sum of those 3 parts, and how long (in nS) is the lenght of a cycle :?::!:

Have a Nice Day.

Thierry

ThierryGTLTS
Offline
Last seen: 3 years 9 months ago
Joined: 2017-09-06 14:18
Posts: 116

Here is the response !

1. HW part DRV8302 (or 01), 10K sets 80nS dead-time, 50µS the min possible + 3nS/1K of resistance.
2. In BLDC Tool or VESC Tool, you can find dead-time compensation, preset to 0.08µS allow the user to reduce the HW deadtime.
3. In mc_interface.h #define mcpwm_dead_time_cycles 60, and a cycle is about 6nS because of the 168MHz CPU clocking.

Have a Nice Day.

Thierry

antonchromjak
Offline
Last seen: 1 month 3 min ago
Joined: 2017-09-05 13:47
Posts: 57

Isn't dead-time compensation for dead-time distortion elimination?

ThierryGTLTS
Offline
Last seen: 3 years 9 months ago
Joined: 2017-09-06 14:18
Posts: 116

On the DRV8302, you can find:

The DRV8302 uses automatic hand shaking when the high side or low side MOSFET is switching to prevent current shoot-through.

The problem is that the definitions of the "Deadtime" and "Handshaking" are a bit fuzzy, if anyone can explain me the difference, it would be kind.

 

Automatic Handshaking is used by TI in their driver devices, and it's very useful to prevent shoot-through without the need od adding too long deadtime.

But it seems that it doesn't work well in all circumstances.

So adding a deadtime can solve those problems.

But I don't know if the deatime compensation adds or substract to the HW one defined in the DRV.

 

Have a Nice Day.

Thierry

antonchromjak
Offline
Last seen: 1 month 3 min ago
Joined: 2017-09-05 13:47
Posts: 57

I think deadtime compensation don't change deadtime but only eliminate its negative effect at low rpm https://granitedevices.com/wiki/Dead-time_distortion.

ThierryGTLTS
Offline
Last seen: 3 years 9 months ago
Joined: 2017-09-06 14:18
Posts: 116

Someone says me that on original Benjamin Website forum.

1. 50 nS minimum added to the handshaking. There is an internal hand shake between the high side and low side MOSFETs
during switching transitions to prevent current shoot-through.
2. I think the timers are clocked with 168 MHz so one tick is 5.95 nS (when the value is 0 to 127).
3. This is used by SW to compensate for the HW dead-time, not added.

An it's the best answer I've received to my question.

Have a Nice Day.

Thierry

TechAUmNu
Offline
Last seen: 3 weeks 4 days ago
VESC Free
Joined: 2017-09-22 01:27
Posts: 571

I have been trying to increase the deadtime, but no matter what I set it to on the #define mcpwm_dead_time_cycles it makes no difference.

Am I missing something?

 

Edit: Nevermind it was not actually uploading the firmware.

welopo
Offline
Last seen: 3 years 3 months ago
Joined: 2019-03-30 08:58
Posts: 1

Total time of the west project is minimized for the citizens. The visitors of the main page are evaluated for the humans. The projection of the west bank is ignored for the candidates.

ArchibaldDouglas
Offline
Last seen: 1 year 4 months ago
Joined: 2021-02-25 10:00
Posts: 1

I know there is someone who may asking what is a case study paper and how to write this kind of academic paper. I can help you and write it for.

KettySmith
Offline
Last seen: 1 year 3 months ago
Joined: 2021-03-10 08:53
Posts: 1

If you have never dealt with writing academic assignments before, creating it will be quite intricate and stressful. Nevertheless, there is no need to panic, as you have a chance to buy a non-plagiarized capstone project on the Internet, for example, from our company.

MargoAdams
Offline
Last seen: 1 year 3 months ago
Joined: 2021-03-15 12:45
Posts: 1

I'm a professional academic writer. We help student who have problems with their academic papers. Many of student feel depressed because of their studies, many of them want to improve their writing skills, many of them want to improve their academic performances. So, our services offer to this students resolve their problems like as writing blog articles.

kim007
Offline
Last seen: 1 year 3 months ago
Joined: 2021-03-25 13:00
Posts: 1

 Want to find a properly written??academic paper??on the Internet? Don???t feel like dealing with this task by yourself? Well, we have a perfect solution for you. The thing is that you cope with this assignment right away. All you are supposed to do is to fill out the order form at academic formatting services website

MikeHunnigan
Offline
Last seen: 1 year 3 months ago
Joined: 2021-03-30 14:44
Posts: 1

I've never wrote a speech and have never performed it. That's why I'm looking for professional writing company to help me write a speech.