New Design 60 Amp Mppt Charger Controller using Picaxe 28X2

Solar Mike

New Member
I came across a great new half bridge driver chip that has user set dead-time and only requires a single PWM input; its the Silicon Labs Si823H4BB-IS1. The chip also has internal input isolation, so is fully isolated from the cpu and its low level control signals, making it a great candidate for building a fully synchronous MPPT PV charger.

I have always wanted to build a design that incorporated the new range of multi-source pin smd mosfets in the D2Pak-7 series, these have low RDSon and low lead inductance, so will be quite efficient at high power levels. The three used here are the NTBGS4D1N15MC, 150V, 185A, 0.0041R, heat is conducted through the pcb, which is clamped via an insulator to a 25mm x 25mm alloy bar bolted to the alloy case as a heatsink. This prototype is only using 1oz copper board so have added some tinned areas to allow soldering extra copper wire to the high current carrying traces. All high current areas are located in the top half of the pcb, low level cpu and controls have their own isolated earth plane with a single point connection to main 0v.

Driver Chip:
24495

Schematic:
24496

24497

PCB:
24498

24499


Will send these off to me made, pending delays for Chinese New Year holidays.

Cheers
Mike
 

papaof2

Senior Member
Looking forward to seeing reports of your test devices.

Chinese New Year does wonders for commerce - something I ordered listed shipping time as "10-15 business days" but the current estimated delivery date is 7 weeks from the order date via "Air Parcel Register". Wouldn't "ocean shipping" have been faster? I won't be able to do more than cursory exam/testing of that new MPPT controller as I'm one-handed for a while after surgery (CMC surgery, repair of arthritic thumb joint - videos on Youtube). Healing and PT can run for months, so I'll be typing slowly and doing very little electrical/electronic for a while - it's hard to solder with just one hand...
 
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J G

Active member
I'm one-handed for a while after surgery
I haven't ever tried to solder one handed, but I have wished for three or four during certain tasks :). Depending on your level of acceptance of "not doing it properly", you could always put solder on the iron and carry it to the joint you want to solder. Otherwise you could try setting the solder up in a jig pointing at the correct place and use your non operative hand to slide the jig across the table to feed it into the correct spot. I am not sure if they are still around, but I have heard of things like hot glue guns that feed out solder, although they mightn't be the best for precise work. As a final suggestion, you could always build a pick and place machine with soldering functionality :).

That mppt pcb does look quite well set from my untrained eye :)
 

premelec

Senior Member
@papaof2 70 years ago I did severe damage to one hand - for months it was just a ball of gauze and packing - I held the solder in my teeth and used the "hand ball" to reduce object being solder from moving too much - I managed to assemble & solder several Heathkits.... - good luck with the inconvenience and heal well - PT works with time.
 

Solar Mike

New Member
I use a hot air gun for soldering the tiny smd components, big items like mosfets and cables I have an RF induction soldering iron station, one handed would be #%$^ hard work.
 

lbenson

Senior Member
I hope that was lead free
In my early teens, I molded, painted and played with near daily 1,500 lead soldiers. It's not like strychnine. But then, a toxic waste environmental scientist I knew later told me that if not for that, I might have been smart.

Now it might be considered child abuse to allow that.

Great project, Mike.
 

The bear

Senior Member
@premelec, Did you fall out of your pram?

@ lbenson, You are plenty smart, not playing with your lead soldiers may have tipped you over the top.

@ papaof2, Good luck with your repair.

Bear..
 

premelec

Senior Member
I guess 60/40 solder lead was not that bio-available as later I didn't test positive for lead content... I knew of a guy with a constantly melted lead pot in a confined space who did get lead poisoning from the fumes... casting tin is much more pleasant - lower melt and good shine.

@Bear - I mangled hand and lost eye [still one eye at age 85] with premature pyrotechnic mix exothermic reaction...
 

mushroom

New Member
Premelec. Several of my close friends experienced premature pyrotechnic exothermic reactions with various levels of damage. Some permanent.
I was lucky to avoid that. As an adult living in a peaceful country I've found no use in these skills developed as a child, and have knowledge that I dare not pass to my children.
 

papaof2

Senior Member
@papaof2 70 years ago I did severe damage to one hand - for months it was just a ball of gauze and packing - I held the solder in my teeth and used the "hand ball" to reduce object being solder from moving too much - I managed to assemble & solder several Heathkits.... - good luck with the inconvenience and heal well - PT works with time.
I know that PT works and I'm very aware of the time return to "normal" requires: L4-L5 fusion, rotator cuff surgery, etc. I have been encouraged by some videos posted by those who've had the surgery and the "opening jars" report of someone 2 years down the road tells me I could have very good results. Most surgeries which have been done 40-50 years have reached a level of refinement - and none of the alternatives (plastic or metal replacement joints) work as well as the older LRTI (ligament reconstruction and tendon interposition) surgery. (animations and actual surgery videos on Youtube for the curious)

I have "solder aids" from the two alligator (crocodile) clips and a magnifier to a frame that can hold an 8 inch by 10 inch PCB, but you need two hands to mount the PCB and I choose not to try holding solder in my teeth as then I can't see through the 5 inch magnifier lens ;-)
I have soldered SMD parts to through-hole adapters to be able to breadboard FRAM chips. I'm doing very well for someone in the second half of my 7th decade.
 

The bear

Senior Member
[QUOTE="premelec,
' mangled hand and lost eye [still one eye at age 85] with premature pyrotechnic mix exothermic reaction...
@premelec,
That was serious, especially at that age.
Regards, Bear..
 

Solar Mike

New Member
Update: Finally sent the gerbers off today, delayed a little due to creating another design. I was intrigued by the possibility of mounting the larger TO-247 mosfets in a similar manner, surface mounted with the pcb vias acting as the heat conducting medium to the heatsink under the pcb; in this case the mosfet mounting bolt clamps the device to the top surface when screwed into the heatsink below.
Have no idea how well this will work, but means I can use the higher voltage devices for PV exceeding 200v.

So sort of threw this one together, its got just the basics to work, no Blinky lights, just an lcd serial display and piezo, have opted for the 30-35mm caps here as I have a box of them that need using up. Edit: the caps I'm using have a ripple rating > 5amps each, cheap no name brand ones just wont work here.

Pcb is 160 x 200mm.
24513
24514



I wont be creating a schematic of this, its basically same as above without the extras.

Cheers
Mike
 
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