Long story short I got swallowed up this school year and not much got done on a projects front. It was really en escapade of screwing  up in some respects from a project stand point which can be gotten into later.

Things that did happen:
-made a generator (read: BLDC motor) for a class, which was really a rework of an existing generator, really the only reason parts of the old generator were used was because its stator was the right dimensions. But its rotor was remade and the stator was rewound and hall effect sensors were added. It was rewound at 50RPM/V, the target was ~100RPM/V; but because I can't do math that didn't quite turn out. Pretty much lesson here is  the average voltage of a rectified 3phase is not the same as the average value of a rectified sine wave... and don't do math at 3am. luckily in the. many thanks to alex and erich in helping getting the rotor machined.

shiny insides

less shiny generator outsides

Stator before rewind

Stator after rewind/adding sensors

Another project was a tool post holder for the lathe/mill combo thingy that was acquired a while ago. The 'millathe' is Maximat7 made in Austria god knows how long ago and probably weighs close to 75kg

tool post sitting on tool post holder it looks like a zebra because  the mill spindle wasn't level and i was too lazy to change it, I like to consider this a stylistic plus.

the failgatedrivetroller was supposed to be a gate driver board for a 3 phase bridge

failgatedrivecontroller has 2 mistakes: mirrored to arduino pinout and forgot the all important ground

The horrible mezzanine thing was made to swap the pinout of the arduino.

Long story short there's been a good amount of fail in recent projects due to messing up details. Devils always is in the details but this leaves rooms for revisions and what not. Considering the pain it is to make boards I'll probably transition to getting boards fabricated by a third party and using a lot more surface mount components. DIL packages have been getting a bit old and clunky and it would be nice to have sexy well done boards with less errors than I would make.

Either way that's whats been happening over the lat few months and I'm going to start a new post to separate this post from a more technical one and shall be babbling about motors among other things.

Things getting done: The beginning of Big Motor

I unfortunately have other things to do than post on the internet but I feel obligated to update this every once in a while so for the maybe one or two people who stumble here by accident so please sit down and enjoy the beginnings of Big Motor (the motor that will supersede small motor). For a scale reference on this motor the air gap OD is 10.5" and the magnets are doubled up to for super poles with 2 magnets per pole, making this a 30 pole 36 slot machine. The model isn't fully done yet, I'm still deciding if I want to attempt getting a second stator of the same type and doing a transverse flux concentrating geometry to avoid magnet reluctance. The attempted result would be a ridiculously high flux linkage and by ridiculous, that is to say something that would just almost saturate the iron with a few 2-5mm of air gap. The operating goal of this linkage would be 1. High torque for low current (hence avoiding magnet reluctance) 2. Avoiding higher harmonics of eddy current losses induced by quickly changing back emf from the magnets (taken care of by the larger air gap). Since these goals are directly at odds with one another some FEMM simulations will be under way to see how achievable this will be. Either way enjoy the picture its Big Motors initial design without any fancy pants transversefluxyness (note: the model isnt done yet).

Big Motor....its big

Power Supply and Vehicle Update

I have been quite busy with school so I'm just going to post some pretty pictures of some of the progress made towards the electric vehicle and power supply. First off here is the transformer. Because I wanted to experiment it is made of a pair of toroids. It is litzed  because this will be run at ~300kHz min making skin depth and eddy currents an issue. The turns ratio is 4:1 and its meant to operate at 120VRMS on the primary side drawing around 10A minimum.

just the primary

with the secondary

The wire is the same stuff used on my motor, its nice because the low gauge makes winding easy, however it has a gnarly polyamideimide coating with astoundingly good mechanical and electrical characteristics coating which much to my chagrin cannot be burned off in a solder pot or removed with standard solvents such as acetone. The easiest ways of removing the coating without a sketchy solvent seems to be sand paper (labor intensive) or propane (not the neatest). At the moment torching it is easiest despite the bits of semi scorched insulation it leaves behind. However to stop the thermal gradient from crawling up the wires and leaving a bunch of damaged insulation I recommend covering the wires in a wet paper towel up to where you want the insulation gone.

On the mechanical side of things I hacked apart a pair of bike frames to be used in the electric vehicle.

Initial bike frame

It is amazing how much less space a bike takes up once it has been reduced to a pile of tubes; even more amazing is the destructive power of a sawzall on a bike frame.

A pair of bikes that were attacked by a sawzall

Next step in this process is to strip the paint from the tubes so they can be cut up and welded together. To strip the paint I got some paint removal discs; they kind of make me think  a brillo pad and bunch of sanding discs tried to have kids. However after trying them out, the process is a bit more labor intensive than I want it to be and so I might resort to chemical methods.

....however work needs to get done so until next time.

small motor completed with sensors

The small motor has been done for a few weeks now with hall effect sensors included. so here's a picture.

Looking back on the design its not half bad besides need for the mounting set up, next time the bearings will at least be flush with the motor face if not inset a bit. The next step in this project is to build a vehicle for this motor. I already have an idea in my head along the lines of a mini bike/ scooter, if you've ever seen The Worlds Fastest Indian this will will be a scooter more akin to the motorcycle in that movie rather than a normal bike where one sits more upright. In the mean time I have some bicycle frames to chop into usable tubing and some CADing to do. Also I have a couple side projects and random ideas to post about in the near future with include tranverse flux motors high power AC/DC converters.

hall effect sensors (yay) + less abominable sprocket mount

So as this is being written those hall effect sensors in my last post are drying in place on the stator with 3 poles in between each sensor woot, hopefully I'll post pictures of that soon enough or at least in a timely manner unlike every other post on here. Those hall effect sensors aren't the only thing happening though. I got my hands on an aluminum round ... more like an aluminum patty it was .5"thick x4"diam. These flat dimensions were ideal for making something well... much more flat to replace the last janky rig. This new sprocket adapter consists of a single aluminum flange with a bit of an inset and some small standoffs, the standoffs are only needed until I get some pan head screws to inset into the base of the flange rather than the current socket cap ones.
On the new flange there are only 3 slots for screws rather than six, six is really over kill. To mill these slots I was going to try a easy method of screwing a fat bolt through the middle of the plate and sticking it in a collet block. Unfortunately that didn't quit go as planned and the adapter lost a chunk out of the side.

Top and bottom before attempt with collet block.

after indexing head and collet block

 Unfortunately the collet really needed to be cranked into the block and we were missing the proper spanner wrench to tighten it in there, as seen above the collet wasn't quite tight enough to hold that bolt. Thankfully the slotting worked just fine on an indexing head.

Sprocket adapter flangey thing from its good side

Despite having a bite out of the side it works just fine.

Anyway hopefully this glue will dry soon so I can:
A. hopefully close this motor and never open it again until it dies a fiery death from over current.
B.post about it. 

Redoing Things, Also Woot Hall Effect Sensors

So in the last post I was describing my special abomination. But looking at it makes my inner engineer feel bad  so in the near future it will be remade using a single chunk of aluminum that the sprocket can be mounted on. Also small motor is under going a few changes do to the fat assery of the bearings there was a bit of rubbing on some heat shrink so I turned on of the plates to seat the bearing around .125" farther out from the stator. This seems to have fixed the rubbing problem. On a side note all hot glue in the motor used to hold down wires will be removed from the motor after talking to Charles about fears of oozing thermoplastics getting all over the place.

Sexy red heat shrink

But on to something not about me messing up: HALL EFFECT SENSORS (read that again with enthusiasm and a disregard for the preceding paragraph) they tell where the magnets are in the motor which is *sometimes* essential for starting a brushless motor from a dead stop. I'm going to stick hall effect sensors in my motor soon but am currently out of town so I'm ti babble about hall effect sensors for a while. Now there are sensorless motor controllers and sensorless brushless motors, however to start from a complete stand still with a large amount of inertia you want sensors. The sensorless controllers work off of the back emf from the phases, the voltage from the changing magnetic flux tells them where the magnets are and when it is appropriate to turn on a particular phase buuuut to do this you need a bit of a spin to figure out the magnet placement. Therefore in vehicles where you want to be able to start from a stop, hall effect sensors are nifty things. Timing with hall effect sensors is analogous to the timing of cam shafts in a car engine; firing all 6 pistons (or 3 phases if its a motor) at once will get you nowhere but when things are done in the proper order you get rotation.
Generally in a 3 phase sensored motor you'll have 3 sensors. Each hall effect sensors i will work with (ATS177) are effectively flip-flops with some hysteresis and can tell the direction of the magnetic flux through the sensor. Because there are 3 phases and 3 sensors we want each hall effect sensor to be 120 electrical degrees apart (not necessarily physical degrees). The difference between electrical and physical degrees for the magnets is Eelectrical.deg=Physical.deg*polepairs (start at 0 after each 360) note: there are 20 pole pairs in my small motor, because of this there are several theoretical positions to place the hall effect sensors; really though there aren't many practical places you'd want to put them. Below my crappy illustration attempts to show this (for a prettier illustration of almost exactly the same thing see Amy's blog where she pretty much did exactly what I'm about to do), Tm represents 1 magnetic period/pole pair/360 electrical degrees/ the smallest repeatable section to get the proper magnetic pattern. Each colored dot represents a theoretical place where a hall effect sensor could reside. The purple dots represent the closest theoretical placement of the sensors at 120 electrical degrees apart...give or take a bit in the picture.

Motor diagram w/ magnets and hall effect placement

 Practically we want the placement of the hall effect sensors to line up with the stator slots because we physically can't shove them into the 1mm air gap (and the stator phase windings would mess up the readings) so that leaves us two possibilities where the stars align magnet and stator phases line up at spacings of 60 and 120 physical degrees; this is respectively represented by the orange and green dots. One important thing to note is the order of the phases with the placement of the sensors. By following the orange dots clockwise the phases will go ABC but doing the same for the green dots will give ACB. This difference in pattern will make the motor spin in backwards for the same sensor pinout, but that can be fixed by switching any pair of phase wires. Oh and just a note as long as you have 3 phases everything is independent of the winding pattern  but ummmm yeah that's hall effect sensors for now. I'll post pretty pictures soon.

So I haven't posted in a while buuut um yeah while away I've created some sort of abomination to show who ever reads this. On my motor with its fat ass shaft the OD of the bearings is 47mm and because it's an outrunner everything  that needs to turn must be mounted around said bearing and shafts. Its important to note that thin section bearings would have a full 15mm smaller OD...don't buy bearings at 3 am kids. In addition to the diameter issue the bearings stick out from the surface a bit this makes mounting stuff extremely awkward. Rather than being intelligent and spending a bit of money to buy a chunk of aluminum to turn down to a proper  flanged adapter to fix this, I opted for the cheap approach and used the steel cut out of my magnet can combined with a piece of aluminum scrap which was at one point roughly rectangular and 4 home made standoffs. Which when mounted on the side of the motor form a sprocket on standoffs on plate on a plate on a plate.

Le parts magnet can remnants on motor plate, with in-between plate with sprocket

By their powers combined + standoffs=inception sprocket?

Lo and behold this abomination of mechanical engineering. More later when this thing starts spinning at high rpm.