Lesson CHEAP CHINESE MONSTER MOTO CLONES AND PROBLEMS

Oh.. And 2 of them catched fire.. Yay

WoW!!!
@Simon Husum , you went through 11 MMs?
When do you realise that a MM isn't suitable for your motor load?

Do you know what your motor stall current is?
Do you know how to safely measure stall current without overheating your motor?

With all the VNH2SP30 protection
•Undervoltage and overvoltage shut-down
•Overvoltage clamp
•Thermal shut down
•Cross-conduction protection
•Linear current limiter

You must be severely overloading enough that even the built in protection is too slow to prevent the VNH chip from burning up.
Either that or your motor is rated at a higher voltage than 12v, the motor will run with no problems forward but it the reversals that cause BEMF that can easily exceed the 16v overvoltage clamp.

Do the motors make quite a lot of noise whilst sat in the centre position ?Thats what I noticed with the last ones I bought. Normally one side of the chips get very hot either turn off or blow up lol

Got nothing to do with the motors being not suitable, its all down to crap VNH2SP30 chips which none of the protection works.

Well doesn't that mean that you have exceeded the limits and the protection working or not didn't save it?

Have you read this thread from the start ?? Have you seen how I have tested the MM's with a little rc motor ? Faulty chips are at fault here, you can double these up as 1 full half bridge which equates to 60AMPS and then add another to 120AMPS so exceeding the limits is not gonna happen.

Internal shorting of crap chips I cant say it enough times, if you have another theory, please @OZHEAT explain how we could possibly be exceeding limits and how you have come to that conclusion ?

Hmmm, I going to sound like a nay sayer but here you go....
The MMs aren't designed for heavy and sudden reversals, most commercial/industrial h-bridges are designed so it brakes or pauses the motor before reversal
Doubling up a MM will NOT allow you to control 60amps, it will however half the combined RDson resistance.
The big drawback is that not all mosfets will turn on at the same exact time, there will be some difference in turn-on time.
When one mosfet turns on before the other that single mosfet will take the FULL load, when the second mosfet turns on it will share the current but only if the first mosfet has not tripped the overcurrent and shutdown. If the first chip has shut down and the other mosfet turns on it can't handle the current either so it shuts down the second chip or if the first chip comes back on in time it will share the load. Best case sceniro is both chip's mosfets turn on close enough that it will share load without tripping.

Why does RDson resistance halve? just like putting 2 resistors in parallel it will halve the resistance but not double current due to the above switching mosfet scenario.

What is the advantage of halved RDson? well the heat generated by the mosfet is due to the mosfet's gate resistance called RDson, each H-bridge has 2 mosfets, a high side and low side. ST state that the VNH2S30sp has a RDsHon as 28miliOhm and a RDsLon of 10miliOhm, as I said above bridging 2 chips halves RDson resistance which translates to sharing the heat load making it easier to get rid of the heat in the chip as it is idealy shared by 2 chips

How much current will 2 chips are bridged? thats a bit of a curley one, it mainly depends on the gods and the MAX current one mosfet can really handle till the second mosfet turns on. It will NOT be anywhere close to double amps as you have to get rid of the heat generated in both chips.

Bridging 3 or more MMs together is a very bad idea, why? Well now not only do you have slight differences in mosfet switching you will have the added signalling delays due to slightly different lead lengths and be certain that one mosfet will not handle 90......120A.

Well yo got that point right.
I have it running just fine at the moment.
But the MMs couldnt figure out a deadzone less than 5 in the SMC3 code.
Plus it showed that one of the gearboxes were not alligned correct from the beginning.
So that costed some.

Yes @SilentChill..
Exactly.. have used the MMs on some wipermotors before my 90zyt without any problem. But the sound they made in centre position is much less after I have changed my deadzone a bit up.
But still they tend to begin a little overheat you I make an uneven pressure whilst sitting in my chair.
When I'm playing I cant get the temps over 35 degrees.
So it makes no sense to me

Yup nay sayer Totally irrelevant .........

We have good MM's and proven to work as dual H-Bridge just ask @Pit with his winch motors. Also @SeatTime has been using his dual MM's for months with no issues once he got good chips. I have decent ones which have been working for well over a year.

@OZHEAT why would "ST" say to use them as a full half bridge in the spec sheet if there were problems with mosfet timings ?

They be like "Yeah use it as a Full Bridge but ya takes ya chances with it blowing up"

You are completely missing the point of this thread, these are known issues with the shit chips, and the chance we take in getting bad ones from china. Just 1 legit original proper VNH2SP30 chip costs twice as much as a fully built chinese MM clone.

Did not read all here, but I made the same experience like @SilentChill. What is theoretical, what is real - the reality is that my MMs (bought 3 years ago) are still running on the 750W winches (dual single bridge = 4 MMs combined). Since then I am driving almost every day (except holidays). So far still NO ISSUES. One year later (that said 2 years ago) I bought from different ebay dealer a few samples, many of them have been crap. At least the MMs are more than only a few times approved, IF we get good samples. If not, the shit is blowing and burning like hell lol

I suppose if you go and try many different MMs you may get a combo that will work but its a trial and more error thing.
Also, soften up your profile enough so hard reversals and acceleration don't overload the MMs

@OZHEAT why would "ST" say to use them as a full half bridge in the spec sheet if there were problems with mosfet timings ?

They be like "Yeah use it as a Full Bridge but ya takes ya chances with it blowing up"[/QUOTE]

Hmmmm, lets see what ST say in their VNH2sp30 data sheets.


Look at the note in above pic. Although they use their 25degC ratings of Ron(Hs) 14mOhm and Ron(Ls) 5miOhm giving a total per leg of 19mOhm. Bridged h-bridge gives 9.5mOhm which is exactly HALF.

You seem to think it is a viable thing to counterfeit the VNH2sp30 chip, how many do think they sell?
These h-bridges have a very, very limited market compared to consumer goods.
It is however viable to just buy the real chips from ST and produce a pcb board. I do take note that you say it cost YOU twice as much for a VNH2sp30 than you spend on 2 MMs BUT manufacturers don't buy in single quantities, rather they would be buying reels and reels of them and that would bring the cost per chip down to 30-40% of the single piece price.

If anything it would be the construction of the MMs that may cause a fault, mainly the thermal transfer pads may not be fully soldered between the chip and pcb.

As a final note Pololu don't rate their VNH2sp30 carrier boards as 30A cont like sparkfun. They rate their VNH as a 14A cont, 30A MAX pulsed.

Have a look at this page by pololu https://www.pololu.com/product/537
cheers

@OZHEAT oh my, where have you been for the last 18 months.................

"If anything it would be the construction of the MMs that may cause a fault, mainly the thermal transfer pads may not be fully soldered between the chip and pcb."

Really ????? finally we agree on something, however internal shorting of the chips has nothing to do with heat pads or resistance per leg , the problem is the chinese either cloning or buying b-grade chips.

Just wondering have you ever had any personal experience with using these boards ?

Hi @OZHEAT , tried to find you project thread , but nothing showed up - can you please post a link - thanks.

Specs of the MMs:

• Practical Continuous Current: 14
• Maximum current rating: 30 A

Sparkfun never rated the VNH2sp30 at 30A continuous current...?

@SilentChill

@SilentChill Chips shorting is the symptom has EVERTHING to do with the RdsOn, current and the heat of the mosfet's junction.
If the chip can't get rid of the heat caused by the mosfet's junction resistance it will get to a point it will overheat and start smoking.
B-grade chips? why would ST sell faulty/subpar chips especially when they have their logo on it, wouldn't that run the risk of getting a bad rep for dodgy chips... get real.

Look at the VNH2sp30, its design is to get rid of most if not all of its heat through the thermal transfer pads and anything on the case is supplemental.
If you don't think the pads are important, think of it this way. what transfer heat better, plastic/epoxy or continuous metal leads/pads?
Add to that the copper track/pad of the board used as a heatsink/heat spreader.

I can see how soldering the board being difficult and looking at you pics they do kind of look cold especially the transistors.
Soldering the chip wouldn't be the same as most surface mount due to the thermal pads and heatsink copper taking a lot longer to heat than the leads and other components.
Maybe reflow the boards adding a little solder paste to the pads best you can and preheating the pad area of the pcb with a heat gun before placing in the oven.

As for my experience with these boards is NIL but it doesn't take an EE to see in your pics that what is happening to the chips. Blown mosfet junctions and arcing.
Id rather use higher voltage, low current than low voltage, high current. More to do with cable sizes and terminals than anything else.
The biggest advantage of 12V is that you can use automotive grade products and chips which is cheaper to produce because they don't need to rate/size for a high voltage.
I did entertain the idea of buying some and using it as a carrier board for a VNH3sp30 being the only main difference is there is no current sense output.
I consider myself a hacker of electronic/mechanical products, love to repurpose. I would build my own h-bridges, hack a board or maybe use a driver chip liberated from some electronics board.

Here it is www....
wait there is none.

I am doing a steering wheel first then will do motion after that.

LOL @Pit just goes to show say it enough times people will believe you.
My mistake, its comments like

I should of checked what sparkfun actually rate em at, instead of assuming.
It was when I looked at the pololu site regarding their drives and their ratings that I was surprised hence the comment.
So maybe you should correct the people who say that the MMs handle 30A and 60A bridged here on this site.
I suppose it all starts with manufacturers half BS in the specs saying their chip is capable of 30A cont in large text but in small writing elsewhere that it is @ 25degC but that ain't going to ever happen unless you can directly cool the die.

This is my last post on the subject of MMs,

Cheers

I give up dude glad that's your final comment.......

So what did we learn from all that . I think I will let my budget and 40 years in the Industry guide my hand..Sim running fine for nearly 12 months now - must be an abomination .