Paul & Sabrina's cheap DIY 144v motor controller

[Wherewolf]

Originally Posted by MPaulHolmes

What's the diameter? Can you take pictures of how you mount the motor in the car?

Don't have it in the car yet....don't have a car! Still looking for the right deal, but I'm still fixing up the motor - I don't have the endplate back yet or the new brushes in hand. I don't want to hijack this thread, but I'll post a couple so you can see what I'm talking about.....

Wherewolf

Btw: These motors need to be disassembled periodically (6-12 months - maybe more often) to have the carbon dust removed. So I'd better design a mounting that allows easy removal!

[xtian999]

Can the PWM logic part of this controller run the power side of a 72V GEM controller?
Thank you,
Xtian

[Roger Heuckeroth]

Originally Posted by SteveU

I’ll make one more suggestion: Ask your controller experts if rewiring the motor to bring out the field coil separately could be useful, both for improved speed and torque control, and for regenerative braking.

Way cool stuff guys,
Steve

Steve,

There is a whole other line of controllers that have this ability. They are called SepEx motors/controllers. Unfortunately, the motor and the controller go hand in hand. The field windings on these series motors are made up of a few turns of big wire. The field windings on the SepEx motors have many more turns of smaller wire. This allows the field winding current to be a fraction of the armature current. Its nice for regen, and also, you get more efficiency since you can limit your IR losses by holding current steady once you hit saturation.

Roger

[lumberjack_jeff]

Originally Posted by MPaulHolmes

Don't worry, wiki coming soon.

What can we do to help the wiki?

It seems like a person could distill the information you've already shared on this thread into something more user friendly, hosted here or somewhere else... allowing you to continue with R&D.

I'm sure that like SteveU, there are visitors who could provide good advice provided they know the design parameters, and the steps you've taken to get where you are.

A thread is a great way to collaborate. It's a less-good way to educate.

If I haven't told you lately, this project is teh awesome.

[Roger Heuckeroth]

Originally Posted by MPaulHolmes

I'm hoping for 40-50 mile range and freeway speeds. That reminds me: I want to learn how to make professional adapter plates and couplers. The mill probably could do the adapter plates. I don't know how, though.

Paul,

I think Pick-up trucks are the ideal "Lead Sleds". They are made for the weight, have plenty of room for batteries under the bed. Plan on at least 24 T-145s if you want to have a 40-50 mile range.

Adapter plates are tricky. I have heard they that the motor shaft should be within 0.001" of center, but I know quite a few that are not even close to that accuracy, and don't have any issues... yet. My idea is to make the adapter in two pieces. The one piece gets secured to the transmission, The other piece gets bolted onto the motor. Then you mate the two together and run the motor with a 12 V battery. You move the two plates around relative to each other until everything sounds good and you feel the least amount of vibration. Then tack weld the two plates together. You can then finish welding, or use screws to attach the plate together.

I found a very simple was to make a clutch-less bushing using a taper lock gear and the old clutch plate. The taperlock gear is right out of a catalog. I bought it from McMaster Carr for around $60. You can find them for less on Ebay. Then grind off the rivets that hold the clutch hub to the clutch plate, so you have just the inner hub. Then center and attach it to the gear with grade 8 cap screws. I could post some pictures if you want.

Roger

[Wherewolf]

Originally Posted by Roger Heuckeroth

Adapter plates are tricky. I have heard they that the motor shaft should be within 0.001" of center, but I know quite a few that are not even close to that accuracy, and don't have any issues... yet.

(I "think"; I'm just a farm boy not a mechanic...) on most transmissions, the input shaft tip (thru the clutch plate) is carried in a pilot bearing or bushing on the flywheel side, so it stays very centered. When you adapt it to an electric motor, that kinda goes away, so my concern is the wear on the input shaft bearing on the transmission - I can see that becoming a leaky problem and wearing quickly with any sideloading or wobbling during rotation. I think I'm going to mill a pilotshaft bearing into the end of my armature shaft, and couple over it, with a carrier bearing on my adapter plate....just thoughts...

Wherewolf

[SteveU]

Originally Posted by Roger Heuckeroth

Steve,
The field windings on these series motors are made up of a few turns of big wire. The field windings on the SepEx motors have many more turns of smaller wire.
Roger

Thanx, that's what I expected. So, assuming rewinding the field is undesirable, we do a buck conversion to produce a low voltage/ high current for the low-z field winding. Since we want a field controller anyway, it comes for ~free. Next question: how bad are the field core AC losses? ie do we need an external choke in series? Probably a good idea for EMC compliance anyway?

Intrigued: By reducing the field, the armature has to spin faster to generate a back EMF that matches the input. Some big AC motors use this for speed control, but if the field supply fails the motor goes crazy. Likewise, an automotive alternator is controlled by controlling the field current.

A basic concept is that the motor current is the difference between the input voltage and back EMF divided by the coil resistance, so as the torque load increases, the motor slows down a tiny bit, reduces the back EMF and the current increases, pulling harder. So the motor speed is a function of input voltage divided by the field current. Of course, there are practical limits like the field current must not be too low.

Steve

[nubie]

Originally Posted by Wherewolf

(I "think"; I'm just a farm boy not a mechanic...) on most transmissions, the input shaft tip (thru the clutch plate) is carried in a pilot bearing or bushing on the flywheel side, so it stays very centered. When you adapt it to an electric motor, that kinda goes away, so my concern is the wear on the input shaft bearing on the transmission - I can see that becoming a leaky problem and wearing quickly with any sideloading or wobbling during rotation. I think I'm going to mill a pilotshaft bearing into the end of my armature shaft, and couple over it, with a carrier bearing on my adapter plate....just thoughts...

Wherewolf

I don't see a problem with getting rid of that bearing, because the input shaft is now coupled directly to the motor, without any clutch. If they don't rotate at different speeds there is no reason to have a bearing.

It also depends on what kind of transmission, if it is a RWD 4 or 5 speed then the input shaft will be supported by a single large bearing and a pilot bearing to the output shaft. Then the "clutch" pilot bearing may be important.

As I say though, I think the electric motor bearing will do fine at supporting it, it isn't like you will have the trans spinning unsupported ever, as it originally did when the clutch was released and it was dealing with the clutch disk.

Most transmissions do have a pilot bearing, but not VW FWD transmissions. It is entertaining because there is a pushrod that travels through the mainshaft on the trans to release the clutch. The clutch is backwards so the pressure plate is bolted to the crank and the flywheel is put on over the friction disk.

Germans are sorta weird, but I think that clutch was only used from 1975-6 through 1999.

[Tango Charlie]

Gosh, I must've taken a wrong turn. I thought for sure this was the Open Source Controller thread...

I blame Paul. He said "adapter plate".

[Wherewolf]

Originally Posted by nubie

Most transmissions do have a pilot bearing, but not VW FWD transmissions. It is entertaining because there is a pushrod that travels through the mainshaft on the trans to release the clutch. The clutch is backwards so the pressure plate is bolted to the crank and the flywheel is put on over the friction disk.

Germans are sorta weird, but I think that clutch was only used from 1975-6 through 1999.

Very True....but man! oh man! That's THE EASIEST throw-out bearing change you can EVER do..... pop a 3 inch cap, loosen the clutch cable, pull it out with your fingers and slap the new one in place! No tools other than a screwdriver to pry the cap off! Hahahahaha!

Wherewolf

EDIT: OK OK Enough! Back to the controller