Tutorial MotoMonster Dual Half Bridge - 60A Continuous and 120A Peak (12V)

Excellent work and it has opened up a Pandora's box of possibilities for low cost DIY sims. Eg. I just ordered a few to have a play with .

@Pit : was your winch like this one? I'd like to have your advice

@Pit
Wow, I didn't know winches can move that fast

I was always under impression that they are slow but powerful, this setup of yours moves really good.
What RPM is that?

Oh sorry mate for the lack of response, in fact I am using this kind of winhces but as far as I konw there are different samples on the market (meaning the quality of the planetary gear) and power output. My winches draw 750W and 120A at max load.

~23 RPM only, but the lever (in this case the crank) is 15cm long, I am not able to calculate the effective speed

The effective speed is dependent on where the arm is sitting on its radial path. In your case it can reach a maximum of 361mm per second at centre. 750W motors, do you know the stall current? No wonder they work better now.

@SeatTime stall current? You mean the current to hold the position?

PS: the winches already worked very well before, PWMax 180 and Kp 380 w/o issues. I was able to rise kp but not the power, now I can drive them at 225 and kp 500 but higher makes no sense due to the awaiting destruction of the rig.

Hi @Pit Stall current is the current measured when the motor reaches its maximum load and fails to move. It can often be induced in our sims on multiple fast changes in direction, which can overload the motor drivers. It is normal quite a bit more than the rated current. Using a balanced rig and 750W motors you would have only seen this when pushing them hard. Example specs from a 12vDC 600W motor below: - note the stall current.

Model: 130ZYT

• Forward Or Reverse Directions

• Rated Voltage: 12V or 24V

• Rated Power: 600W

• Rated Current: 66A@12v or 33A@24V

• No load Current: 6.6A@12V 3.3A@24V

• Stall Current: 199A@12V 99A@24V

• Rated Speed 1500 RPM (12V/24V)

• NMRV Gear Ratio 80:1

• Final Output Speed (Gearbox): 18 RPM

• Rated Torque 143nM (the torque can go much higher, but the maximum torque you should put through this box is 143nM)

@SeatTime I am coming back to your request I don't know the stall current of my winches. When using standard MM or MMs as a half bridge driver if the motors did a very fast oscillating the bridge stopped working. Using two MMs/motor no more issues.

any news about your experience?

SMC3 can handle 3 motors so 6 MM's/Ard are quite possible.

That is exactly what I would expect, your stall current is obviously over 60amps but under 120A. If you installed a shunt and connected a oscilloscope (normal current meter would likely not catch it), you could measure it. Also it makes me wonder if you have actually got 750w motors? I would expect to see higher currents - or maybe your just not loading them up with a balanced rig.

sorry, I built a slingshot with my son instead
I'll keep you informed

The current raise equivalent to the load respectively to the weight. Cannot explain it better but the needed current is not so high, the peaks are very high which result in shutting down the drivers. Edit: did a fast smartphone paint

Nice, what was the maximum current?

I have a Clamp Multimeter UNI-T which is not the really fastest on earth but a test run at nordschleife it says between 24 and 45 A in maximum.
Slow "Standard" driving the motors draw only 6-10A.
I was using 30A car fuses before upgrading which have blown after upgrading to Dual Hal fMM. Now each single output of the MMs are secured by a 25A fuse (50A total), no issues here so far. Fuses can resist against peaks a very short time.

In SMC3 you can reproduce very well the peak using the square mode. As heavier the weight as higher the peak. Using high values in SMC3 the driver has been stopped immediately (before upgrading). Now I can do what I want, they do the job.

I repeat again: not the needed current is the big issue of big motors (depending the weight), to overcome the hurdle the driver must handle the very high peaks.

I guess you know that the rated current for a 750w 12V motor would be at least 63 amps, even just the inertia of the armature during high speed transitions can generate high currents on big DC motors. A motor driver should match the motor. Eg Allot of us use JLK 12v12 which are rated at 12amps continuous and 30Amps peak. These are normally mated with 200w 12V motors with a rated current of around 16amps. With cooling the JRKs normally handle these fine with the high speed transitions that a 150 RPM motor can generate. Seen up to 40 amps peak.

That's awesome! That's what I'm going to build. 2 mm's per motor. 180w motors.

Good luck! Please do so but step by step, if you never had one MM begin with one MM first. When you have any more experience try two MM. The MM are protected but bad wiring destroy the drivers probably.

Ok thanks, a slow and steady approach for sure

Just a question Pit, I'm sure it's in your post somewhere, but which locations do I connect to the arduino for the second motor? A0 for motor 1. A1 for motor 2? Motor 1 (2) arduino, (8,7) MM's. (3) arduino, (9,4) MM's. (9) arduino, (5,6) MM's. Motor 2 (4) arduino, (8,7) MM's. (5) arduino, (9,4) MM's. (10) arduino, (5,6) MM's. I think this is right but wasn't sure about pot for motor 2. Wire it to A1 from the middle connector on the pot for motor 2?