We were asked recently about our experiences with motors and controllers in the ProEV Super Coupe.
When we first got the Blue Sky Chassis, it came with a unbadged brushless motor and no controller or batteries. For the first two years, we ran the motor with a Sykromotive prototype AC controller and 48 volts of lead acid batteries. This was a very effective combination with efficient operation and strong regenerative braking. An additional advantage was the data output from the motor giving access to information about amps, voltage and RPM. A disadvantage to the controller was it's 'hard' lower voltage limit that shut down the controller when the voltage sagged rather than limiting current to keep the controller above the set minimum voltage.
We continued to use this controller when we switched to the 59.2 volt nominal lithium pack. This was near the upper limit of the controller's rating and probably contributed to the controller failing after two races.
We moved to a Kelly Controller (~$140) http://kellycontroller.com/keb48200x24v-48v150a20kw-bike-brushless-controller-p-58.html?osCsid=vuc3654o292jf2k07ra4s0m5p0. Despite receiving a number of custom firmware updates from the Chinese company, we were never able to get the regenerative braking to provide more than a couple of amps. There was some question of the efficiency as well probably due to the simplified choice of settings not matching our motor. The controller software was easy to set up and pair the controller with our motor.
We then installed an Adaptto Maxi-e controller(~$745) http://adaptto.com/Products/Controllers/. The auto install did not come up with working settings. The manual is a rough translation from Russian but the controller software has multiple adjustments to allow extensive customization to fit the motor. We suffered through a number of races where the motor would run poorly with both the motor and the controller overheating. We finally did a series of straight line tests with full DAQ to establish reasonable settings.
This controller's advantages include multiple adjustments and a display/controller module that allows rapid changes in settings, as well as a screen displaying battery capacity, current, voltage and speed. Adaptto also offers an integrated Battery Management System (BMS) and charger. The 'soft' minimum voltage limit allows current to be limited as voltage reaches a set lower limit. This means the vehicle slows as the battery reaches empty instead of cutting out under voltage sag.
The disadvantage of the system was how hard is was to get working and that there is no easy communication protocol to allow access for voltage, current and RPM data for building your own custom display or DAQ system.
We are now running the BAC 2000 controller ($300) http://www.ebikes.ca/shop/electric-bicycle-parts/controllers/c-bac2000.html. This is a Field Oriented Controller which is claimed to offer efficiency advantages over traditional controllers. The software is not well documented but offers great flexibility and works well. The controller uses Modbus protocol to communicate which means it is fairly easy to use an external computer such as an Arduino to track data such as motor RPM, Amps, Volts, Motor temperature and send commands such as resetting the current limit on the fly.
The disadvantage to this controller is that it is a little bit of an orphan for support. Ebikes.ca have instead developed the Phaserunner (~$295) http://www.ebikes.ca/product-info/phaserunner.html which is a similar concept but easier to use, more durable and slightly less powerful. The Phaserunner works with battery packs between 20 volts and 90 volts. It will run at 45-50 amps continuous without a heat sink and 90 amps peak. The software is suppose to be simple but flexible. It integrates nicely with a CycleAnalyst to display amps and volts etc (~$125) http://www.ebikes.ca/product-info/cycle-analyst-3.html. It also uses Modbus allowing integration with an Arduino for those interested in programming.
Our unbadged motor died from over heating while we were running the Adaptto. We did research and come up with the 3220 Astro Motor ($695) as a replacement. https://www.astroflight.com/3220-astro-brushless-motor-details.html
This motor is very light (4 lbs) and very efficient over a wide range of conditions. It required some machining to make work. We are running a 10 tooth go cart sprocket and had to machine the motor shaft to secure it. We are running a 110 tooth #219 go kart gear bolted to a 16 inch bicycle wheel. We had to machine an adapter to attach the go cart gear to the standard bicycle brake hub. We also had to fabricate a band around the motor to attach it to the chassis.
For more about what we were looking for in a motor, go here: http://electrathonamerica.activeboard.com/t62894806/best-motor-on-the-market/?page=1#comment-62898991
I am fairly sure that our motor choice is one of the most efficient available. It is expensive and I suspect that there are similar motors available at a lower cost. A chain drive offers some advantages in being able to change the gearing but it is difficult to make reliable. We have had problems with sprockets coming loose, misalignment of the gears, chassis flexing and throwing the chain, bottoming the chassis and throwing of the chain.
A number of top teams (Electrocutioners, USF) are running hub motors. These motors might be slightly less efficient but never throw a chain.
Here is a useful online tool to help think about motor choices: http://www.ebikes.ca/tools/simulator.html
For those reading this, Cliff knows me and knows my cars (we're both from Florida, but race in different classes), so this is just for general info:
Cliff mentioned thrown chains above. When I was mentoring the Astronaut High School team we had a Blue Sky car. Chassis flex was a problem with it because of the poor design of the rear frame section. We constantly battled thrown chains. We started out with bicycle chain and sprockets as described in the assembly manual - all junk. Bicycle chain is not heavy enough and is prone to stretching. We switched to #35 go-kart chain and sprockets. That was a significant improvement, but chassis flex was still causing occasional thrown chains. Finally, I used a bicycle fork bolted to the rear wheel mounting plates and welded to the roll bar support - no more flex. Whenever we threw a chain after that, it was usually because of misalignment of the sprockets and I had the same occasional problem with our other cars. Arthur Schang from Milton High School suggested that I switch to #40 chain as he had done to his team's cars. I did and have not thrown a chain since except once when my motor mount bolts came loose.
I know this was a bit off subject for this thread, but thought it may be helpful to someone.
when we ran the ME1003 which had 30hp, even being aggressive on the throttle we never had any chain issues with the #40 Go Kart chain, Hub motors are really great since they are light and you can make your car shorter since you dont have to run a chain, but you really have to nail down your setup and you have to be careful what spokes you use, how the wheel is laced and alot of other things that we learned the hard way. In my experience running a mid drive system was a little more difficult to get right on the initial setup, but after that i had very few issues, but the hub motor was the opposite, very easy setup, but alot more constant work to keep it working properly
