Tutorial "HPMC" High Power Motor controller H-bridge using N-MOSFETs

Hi Speedy,

first of all, thank you for your reply and suggestions. (I am impressed about your patience with me... as I said, absolute newbie when it comes to electronics...THANXS!!)

What I did yesterday evening:

- Have NOT changed any of the capacitors. (coz I still have to pass by the shop to get new ones)

I did however write a code for the Arduino (I am using a Nano right now for testing purposes) giving me a PWM on PIN D3 (i think that is default for the 980 HZ operations) that I can control.

What I have noticed is that when I use values of about 200, I get pulsation..(On, off, on, off, on, off). The lower I go down with the PWM cycle the longer the on pulses are vs. the off pulses. At 30 I get constant movement with no off pulses. Changing motor rotation works just fine. (same picture in both directions)

I have checked by bridging the PTC that it is not limiting. As for the length of the green wires, that is for testing only. The final build will be a bit different. (explanation below)

I will retry the experiment and update you once I have the new capacitors as you suggested. I have read in one of the threads that you need "fast" capacitors. Best to use Tantalum. Any view on this from your side? (In any case, I have ordered various versions...)

Thaks for your help so far...

(Below Picture shows the motor running (with Pulses))




SIDE Comment:

I am using (or at this stage trying to use) your HPMC to control my 4 ROV thruster motors. They are 450 W, 24 DC geared motors. On each side of the underwater ROV I have Power pods that house in each a transformer (440V to 24V / 5 V and rectifier) and I am planning to put two of your motor controller bottom board there. The beauty of the pods is that they have the bottom lid where you can fit all the Mosfets so they get nicely water cooled from the outside. These pods have a pressure rating of 300m, but I'm not planning to go down that deep. I need to have the whole thing running by mid next year so not much time left.

Picture of the pressure Pod inside:

Hi Speedy,

I have just changed the capacitors to 220 uF (25V) as you have suggested. Unfortunately still with the same result. still pulsating...any ideas from your side?
Are there any test points on the board where I should be seeing what when??
I have noticed that during the short motor off pulse, the second red (direction) LED goes on...
IF you PM me your address in Egypt, I would happily send you the board for you to have a look at it via courir? (I dont even need it back, just an answer what I am doing wrong here...)I really do need a solution... All the commercially available boards will not fit my pressure pod...Any Idea is very much appreciated...

Greetings Carsten

Hi Speedy,

i have made some small progess by using a much bigger load. (a windshield wiper...i think that is what you used as well with a geared motor in your video). Whilst the problem is still around, it starts now much later... PWM 235. Somehow I have the feeling it has something to do with my bootstrap capacitors. I might have to revisit my calculation.... and maybe use the correct and final motor for what this is intended in the first place.

Is it possible that the load has an impact on all of this?

Have a good evening.

Greetings

All,

I got it working....YIPPIE!!!!

Apparently after adding 100nF Ceramic capacitors in parallel to the bootstrap caps (in my case I used 220uF)...(and I have no clue what that does), it now works very nicely through the whole spectrum of PWM (Arduino standard 980 Hz on Pin D5). All except 255, but up to 254... Amazing.

Now comes the hard part, making 6 of these and then they have to fit into the pressure pods.

Ill post a pic when done.



Greetings Carsten

Well done @carsten, I admire your perseverance in resolving the issues you were having with your build . It has given me inspiration as I plan on building a few of these myself with probably less electronic knowledge than you posses. It does seem a bit daunting but hopefully a great learning experience and with great minds like @speedy behind the project I am looking forward to getting mine under way, just have to find the time as I have acquired most of the materials to start.

Congratulations @carsten ... Good job
Some of Golden silence always gives its rewards .

Is it possible to augment the resolution (tick) of the encoder?

What Encoder ?

Hi Speedy! First of all, great job! Its a excellent work!

Do you have a eagle format? I would like to cnc this pcb.

Thank you very much!

As For easy sourcing a good components that works like a charm from the first time and furthermore making the copper disk ...
I'm in the phase of making such thing to be just assembled and put it on ebay myself ... I'll put the link later .

Regards ...

@denyszandonadi ...That file was in the sprint layout format ...won't exported to eagle .

Hi i try this controler and everything work whith small motors but with powerful motor with about 30 amp and 3,9 khz pwm at 92% i got 2 diodes fried. I think . I look on the scope and pulses did not look ok. I tried to put some capacitors to filter but no.

you mean like this

30 Amp. is a small wiper that should run flawlessly with this design ...
Can you attach some photos ?

Yes like this but negative spike is little bit longer. at he moment i dont have pics. Wiper motor is ok. I mean servomotor from car power steering its about 500 watt.

I forgot to mention that pwm is 31 khz.

Until you upload some photos of your build ... I guess you need to use the full 9 diodes 1N5819 beside the MOSFETs ...

so they are able to absorb all the fast repeated Spikes and EMF falling current coming from the motor at the 90% and higher PWM duty cycle ...

There is all of them but fried only 2. 1 from 3 upside and 1 from 3 in downside or other maybe in upside dont give attention because of circular design(i like it).

there are 6 diodes in upper side +ve supply /3 for each MOSFET side "motor direction " ... the same on the lower side -ve supply ... they work together in a cross section for each motor direction ... So , which diodes do you mean ?

@Cvetan Cvetanov ... Please provide at least the lowest bit of information as this is really hard to predict so far ...

You also need to download and read the above application note pdf file ...
P.S. I've sent you some coins .

1 from group of 3 diodes

@Cvetan Cvetanov ... I guess you have a big sparks in the motor brush in this motor direction ...
- try replace the brushes if worn out or flatten their top with a strong spring behind .
- increase No of diodes in this cross section motor direction .
- Lower the PWM frequency by 1/3 if you can .