Hall sensors and motors

I've been working on adding the hall sensors to my motor, I'm putting six sensors in the back motor. I only expect to use 3 as per normal BLDC position feedback but I'm putting 3 more backup sensors in. I have heard they sometimes fail so this means if I do have a problem I can simply switch to the backup without having to teardown the motor to repair it.
I made 6 little pieces of fiberglass circuit board that fit snugly in the gaps in the motor stators, they have cutout pieces for the hall sensors, I'll glue the hall sensors to the fiberglass with polyester resin which I found out is used in the fabrication of the winding parts of AC induction motors. If it is suitable for this then it should be good for my motor too, its cheap and easy to use.
I stacked the motors together and took a photograph, I had to remove the plastic protection guard from the bottom motor as they would not fit with it in place.

I had my first quote back from one machine shop and I'm awaiting more, it will be 4-5 weeks before I actually have machined parts in my hands ready to assemble, so plenty of time to finish other tasks.

Drawings finished....

So finally after a couple of months my drawings are finished enough for quotes from machine shops. Since sending them out I found a couple of missing dims and one dim I had to change but these won't change the quotes themselves.
I have sent them out to places all over to try and get the best price. This can be risky in that I don't know the reputation of some of the places but I'm hopeful it will work out ok.
It will take a couple more weeks to decide on a shop and once I give the go ahead a few more weeks at least waiting for parts to be finished.
I have other work to do while I'm waiting, embedding hall and temp sensors in the stators and prepping other parts. I've also been looking around for some old used car batteries cheap to test my electronics out, its proven to be difficult as even old virtually dead batteries have value for recycling.

Thanks to Tom Staub at High Plains Tool and Mold

My local machine shop didn't have the right tools to measure the stator dowel hole locations properly; so after some searching I found a website where some guys built a Honda Insight with a Tdi lupo engine. They had an adapter plate machined and so must have measured the dimensions I required.
Tom Staub at High Plains Tool and Mold (ph: 303-806-0451, 3201 S Zuni St # C Sheridan, CO 80110-1996) was happy to help and went to the trouble of finding his notes on the adapter plate. Thanks Tom!
Now I can proceed with finishing my drawings.

Design almost finished

I've made a lot of changes to the design, I managed to eliminate one part to save costs and simplify some of the others.

I have a small amount of CAD work to finish off and then tidy up the drawings and tolerances. I have one motor at a machine shop which is being measured to check my dims.

Both motors have cooling tubes

Finished off the second motor, just need to add temp sensors and hall sensors and they are complete.

Offset dim

Pics for offset dimension question on samba forum.

One motor almost finished

Mixed 7oz of silicon RTV with 1lb of iron filiings, it mixed in quite easily. Used latex gloves and applied it to the pre-formed copper tubing wrapped around the stator. I had previously machined in clearance on various places using a dremel etc.
It was tricky to do but I have it finished, I used two zip ties at the tube outlets to hold them in place before adding a lot of pure silicon to prevent the tubes moving around.

Heat

I have decided to water cool my stators in the motors; they are not designed for continuous use in the honda cars so they may get too hot in my EV.
I'm going to use a double wrap of 1/4" copper tubing with an ethylene glycol and water mix pumped with a home computer water cooling pump; the pump will flow around 1 gallon per minute at its maximum output.
There are two places I can add the copper, I can try and cool the copper coils themselves which is where the heat is generated or the outside of the stator assembly itself. I considered trying to cool the coils but I'm afraid whatever solution I come up with is going to risk damaging the coils, even if I get everything mounted ok its possible the tubes may rub and vibrate and wear through the insulation and create a short over time.
I'm going to wrap the outside of the stator assembly instead, I was going to purchase thermal insulation gasket material but its too expensive in the quantities I need for my EV ($300) so instead I'll either silicon them in place or epoxy.
To increase the thermal conductivity of the silicon/epoxy it would be nice to load it with particles that are highly thermally conductive, powdered copper or aluminum would be best but might be tricky to find or be too expensive. I'm considering using talcum powder instead which is magnesium silicate. I found a lot of data on talcum powder and I never knew it was actually a carcinogen, if I use this I'll be taking care to avoid handling it or breathing it in.

Edit: I found iron filings are cheaply available and only cost around $5 a pound, they are also non toxic and should be easier to mix with epoxy or silicone. I bought 3lbs online and they should arrive next week.

Microcontroller

I have been researching what kind of microcontroller systemt to purchase to control the MDM. I did find some powerful but inexpensive ones such as the leaflabs maple:

leaflabs maple

Which has a 72Mhz 90MIPS processor (complex motor control needs about 12-25 MIPS) that uses an open source version of C that is easy to program in. However I would have to write the code for it basically from scratch, this would be a lot of work so I decided to purchase something with more support for motor control with some pre-written library files. I got a microchip evaluation board for BLDC motor control, I also bought an inexpensive BLDC 3 phase motor with built in hall sensors from ebay. I plan on setting up the board with the small motor and getting all the software working, then bypass the mosfet state in the board and drive the honda MDM directly.

microchip

MDM module wiring

With the Honda insight manuals in hand I went through the wiring to the MDM module this evening. I am 99% sure this is correct but I'll double check it before I apply power.
It looks fairly easy to hook up.

Parts

Parts arrive from ebay

Got my parts in the mail. Two IMA rotors and stators and two inverter/DC-DC converters. Unfortunately one of the stators was damaged. The packaging was ok so the ebay seller must have damaged it. Now I have to wrangle with the seller to obtain another stator piece....

Edit: the seller apologized and has apparently sent out a replacement motor unit, should arrive next week

3 phase control

I've been reading up a lot on 3 phase motor control while waiting for my motors and controllers to arrive; I've found a lot of good information online, these are two of the best links:

instructables arduinio motor control

3 phase motor control made easy

Edit: the control is a lot more complex than I thought and will require more computing power, so my initial assumptions were incorrect. Fortunately there are a number of microcontrollers on the market with enough power and some of them have brushless DC library files for easier programming.

More CAD

I bought a flywheel and clutch at the weekend; I measured it up and made a proper CAD model of it. Here's a couple of shots.
I'm still waiting for my brushless motors and controllers; I've been reading up on 3 phase control.

Designing the parts in CAD

I have been working on some concepts to get everything to fit together. I only have the transmission in my shop so I've been using photographs online to estimate sizes and shapes.
I have a pretty good idea how the system will fit together, one large bearing at the flywheel end and a small one at the opposite end. I might use a roller bearing at the smaller end to counteract the thrust load when the clutch is depressed.

Here's an image from my current concept.

How to figure out how much power for your vehicle

In order to size a motor and batteries in a vehicle it is necessary to figure out how much much power it takes to go the speed and range you need.

I use this online bicycle calculator, it can be used for any kind of vehicle as long as you know the parameters:

http://www.machinehead-software.co.uk/bike/power/bicycle_power_calculator.html

For the VW bug, I looked up the CD (coefficient of drag) which was about 0.485. The frontal area is 1.8 meters squared, the weight is around 1140 kg. The transmission efficiency for a car is usually around 85%.

You can then enter a velocity and it reports back how much power at the motor is required to drive that speed.
For my bug I have a maximum of 27hp, so my top speed will be around 69mph, 19.6kw.
Once you have sized the motor you can figure out how far you can go on what sized battery pack. For example at 69mph if you want to travel 69 miles IE one hours worth of travel you would need 19.6kwh (kilo watt hours) for your battery pack.
My pack will be 144 volts because that is the operating voltage of the Honda IMA motor, so divide 19.6kwh by 144 gives 0.136ka (kilo amp hours) or 136 amp hours. I'll be using lead acid batteries which are nominally around 12 volts, so I'd need 12x 136 amp hour batteries.

In actual fact I would need more than that. Batteries have a much shorter life if you use their full capacity, if you only use for example 25% capacity of a lead acid battery you'll get over 2000 charges from it before it starts to age.
You'll only get a few hundred if you run them down real low.
So for the above example I'd actually need 12x 544 amp hour batteries which would weigh too much for the bug.

I'm shooting for a range of 30 miles (at a discharge of 25%) at a low speed of 35miles an hour average. This is fine for driving to work and back and general runs to the store etc.

Brushless drive motors

Just won a bid on 2x IMA Honda brushless motors and 2x inverter/controllers off Ebay. I plan on making a sandwich of the two motors. It will put out about 27hp.

Stand

Made a simple wooden platform to hold everything in place.

Bug transmission

Just got a 1976 VW bug transmission for my motor and transmission build. Spent an afternoon de-greasing it and put it in my workshop. Next have to make a wooden support for it and purchase some brushless motors and controllers.