Microchip TC649 PWM Fan Controller Checkout

It’s Friday, my wife is off head-shrinking so I decided the first thing out of the box of goodies I just got from Digikey was going on the breadboard. Okay… so I lied to myself: a 74HC14… those are just restocking parts from a project I was working out that W2AEW had posted on his YouTube channel (the link is to the Youtube channel, if you’re not subscribed, you’re missing out.) So off to the next part.. A Microchip TC649 ?? What was that again? I don’t know about you but I just put random stuff that looks cool in my Digikey shopping cart until I am ready to place an order for stuff I actually need. Maybe I saw this in an Elektor article? Got me.. but hell PWM Fan Speed Controller with FanSense[TM]… neat! I downloaded the PDF to check it out; I was thankful I didn’t need to break out some i2c to get it running, it’ll run standalone with a thermistor. There is an example of using a microcontroller, I imagine I’ll use close to how their example design is shown. So, embarrassing, I know I have thermistors but I don’t know where they are? I used a 10k 10 turn pot. The Tc649 is looking for 2.7-1.8v No problem. I had a small fan so I used a 2N2222 and 810Ohm resistor for R_BASE. I recommend doing the math on the sense resistor (or it won’t pick up your stall) … They have a nice chart as well in the manual. I HIGHLY recommend sticking with 1uF for the PWM cap.. I played around with that, there is a reason they recommend it. In fact you’ll see my screen shots below are with a 0.47uF cap but the fan stalled while running faster than with 1uF. Not a lot more to say about this? It works! Very well in fact. The fan can just about be completely stalled with your finger (if you’re brave!)  and it’ll continue to run… but you’ll be recycling power unless you build a reset into the circuit (I hadn’t). My circuit was running 5V, fan was on 12VDC (oh yeah, you can use “any fan voltage”) . I’ll hook this up to the first microcontroller to come out of the box later on this weekend! Until then.

 

Microchip TC649 Design Example that I used for my initial breadboard experimentation.
Microchip TC649 Design Example that I used for my initial breadboard experimentation.

 

Channel A: Output to R_BASE on it's way to a transistor ( 2N2222 ) Channel B: Pin 5 (Sense)
Channel A: Output to R_BASE on it’s way to a transistor ( 2N2222 )
Channel B: Pin 5 (Sense)
Channel A: PWM output to R_BASE and on to the transistor Channel B: Capacitor Cf (shown with 0.47uF) determines the frequency of of the PWM.
Channel A: PWM output to R_BASE and on to the transistor
Channel B: Capacitor Cf (shown with 0.47uF) determines the frequency of of the PWM.

VFD Update: In Precharge / Configured

Slowly chiseling away. I got the terminals set up, all the motor set up, disabled most faults in advanced configuration and I now have the drive out of fault, temp sensor back working, and ready to drive waiting on the DC bus.

I think if I read the manual right with my configuration that should be about 370VDC, but I guess we will see? The VTAC9 Rockwell Automation manual is really detailed in some regards but lacking in regards to technical information. Not surprising after looking at the set up the VTAC controller has no idea it’s missing the AC input. The drive does start up right at about 196V on the DC bus … if you have to get one running just enough to configure it. I could/did configure the drive for a lower motor voltage but I won’t know if that effects the requirement for the DC bus; I doubt it.

Now.. I just need to suck it up and buy some batteries. I put in a big order with @Digikey but it’s all subsystems stuff. I’ve never worked with CAN before but the new Elektor has a article about a CAN tester and it interested me enough to try it out.

I also noticed @Sparkfun has a neat little bluetooth module out that I was considering picking up for $59 .. but then they also have a “Silver” one that’s $39 and has 3.3-6V input both Vcc and inputs. They’re small and are set up for TTL level RS-232. My current module is larger, has a lot of pins I don’t use (although I do like the handy link output).

With all this need for HV DC I’m seriously considering building a home-brew HV power supply. You have probably seen my bench I have some cheapo Elecnco 0-20/5/-12/12,  a B&K 1601, and some miscellaneous other fixed sources. I have my eyes on a B&K 9124 and a B&K 9110 (tear down: http://www.eevblog.com/forum/reviews/bk-precision-9110-60v5a-100w-psu-review-%28with-pix!teardown%29/ ).

VFD waiting 'In Precharge' after configuration.
VFD waiting ‘In Precharge’ after configuration.

VFD Update: AC retrofit to DC, Drive Start Up on DC bus.

I said I was going to wait until I had enough batteries to start this drive up but I decided I couldn’t wait. I took a 110VAC to 42VAC power supply that was lying around and fed that into the secondary of the fan transformer (690VAC tap). Through an undersized bridge rectifier I need to change out if I’m going to use it for longer than a brief start-up (400V, yes technically big enough but..). The drive started on it way up to 220VAC as the capacitors charged. I didn’t allow it to stay on long because I have no fan and I got a over temp alarm though, I think it’s not right, 110 deg C. I must have wiggled a cable out? I’ll look around as I think I know where both sensors are found.

So there it is, started up. I have a lot of reconfiguration to do to the drive to get it to run on low DC bus voltage. I was reading the manual and I think I can cheat it down…. I certainly don’t want a 680V DC bus as that’s a lot more batteries than I was planning on.  I haven’t decided if I’ll be running it by potentiometer, 0-10VDC or 4-20mA control signal … I should probably figure out how I’m going to physically request/actuate a speed demand before I decide.

Next steps: 1. Attach DC fans for the heat sink, provide a more securely wired input, configure settings…

Note: 110V 42VAC transformer fed to 110V480V transformer, rectified to supply to 220VDC. The VFD powers up in the 200V neighborhood.
Note: 110V 42VAC transformer fed to 110V690V transformer, rectified to supply to 220VDC. The VFD powers up in the 200V neighborhood.
Below is the 80W power supply board and then above that is the IGBT board with capacitors to the right.
Below is the 80W power supply board and then above that is the IGBT board with capacitors to the right.

VFD Update, Stripped the AC front end.

I removed the input AC components today. The drive had a lot of weight in components just to drive a 110V fan. I’ll obviously have to replace that AC fan with a DC fan. It won’t have the CFM output of the original but I won’t be generating the heat it had. This monster was in a building right next to I-405… you can tell is was breathing a lot of fallout it’s whole life. It’s amazing where the dirt and scum has found to hide and how much there is.

I was happy to see the only thing the AC provided power to was the cooling fan and then straight to rectifiers… that’s great news of course.

I know it was wishful thinking but I threw 160 VDC at it… didn’t even blink. I’m just going to have to wait until I can get my hands on more batteries. My 20Ah batteries are looking like they’re going to be garbage… they’re just too far gone I guess. All the recycling tricks are proving to be crap 🙂

Check out that toroid!
Check out that toroid!

Edit: that board up front is the variable voltage rectifier controller… It is also going to be removed

Sometimes you get what you pay for! An attempt to bring back SLA batteries

If you’re reading this, perhaps you’ve run across the endless forums of magic battery revival modules, advice for adding acid, water, salts.. whatever? I spent a solid day reading/surfing.. maybe there are a few magic ways to save your batteries? I don’t know lets see… but before I start let me say one thing: Have a ten year old car battery you’re trying to make last another two? Well, sit down, this may sting… you’re cheap.. buy a new damn battery! 🙂 I scored four *free* 12V 20Ah SLA batteries.. they were installed 2 years ago.. only lasted in some biomed equipment for about 18 months… why? Who knows.. they aren’t used much.. probably a crappy charging system in a 20,000$ piece of equipment. Worse case I drive a mile down the road to drop off the batteries for recycling (also free).

I refuse to chuck these.. even though they are really in a bad way. Status of batteries: 4-6 Volts… DEAD. Below dead.. and they’ve been sitting that way for weeks. So lets see how these goes! All batteries are close to the same age, came out of the same equipment and are roughly the same voltage. Also of note, these aren’t gel cells.

Battery 1: I put battery 1 on a Powersonic SLA battery charger (12V 4A..) PSC-124000A for 24 hours. the battery charger sat in float the whole time.. didn’t get warm.. didn’t draw much more than 10mA — not looking great.

Battery 2. This battery went through the same 24 hour ineffective charge as above…. I popped off the top. The cells were lacking water, I don’t know what is normal but it looked considerably low. I put about 150mL of water into the six cells which brought it up to just under the vent ports. I also put in two drops of sulfuric acid into each cell (why not!?). I threw it on my current limited power supply 15VDC and I put the current trip at 250mA just in case something gets away while I don’t have my eyes on it. I’ll adjust this later on if needed. It started off at 10mA, but I’m in about 4 hours and i’m up to 50mA… lets see what a day or two does?! Many of these sites mention this process taking a week or two. I’ll put the battery on the powersonic charger once my current gets up to 100mA or so.

Battery 3 & 4… To be continued!

 

VFD Modification: Part 1

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First off I’ve been really tearing it up in my nerdery the last two weeks… It’s messy.. That happens so don’t mind the mess.

So I scored this sweet variable frequency drive (VFD) or also known as a VSD. It’s a Rockwell Automation drive that is to large for my application but it’ll work just fine. I figured I might have to tear out the entire front because I’m feeding it straight DC but they broke out DC to a terminal block ?! I’ll give it a try… I have a 96V power supply that was a long shot but it was no surprise two amps wasn’t enough just to power the electronics for configuration. It isn’t jumped to run… So this beast is a watt-hog just idling. I have a couple batteries I have to pick up in a few days; I am guessing I can start it up on a 48V/19AH string. The power down defaults to zero and I believe it’s set up to run on just enough to run the electronics. I guess I’ll see?! If this doesn’t run on DC (and maybe even if) I’ll gut the AC front end because it’s extra weight. Check out the terminal strip..DC is on the left. Also… In case you’re wondering its about 90lbs.. A lot of heat sink!

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