The "Bonanza Bulldozer" Dual PhaseRunner 2WD eMTB

General Discussion about electric bicycles.
User avatar
Alan B
100 GW
100 GW
Posts: 7041
Joined: Sep 11, 2010 7:43 am
Location: San Francisco Bay Area, USA
Contact:

Re: Bonanza AWD eMTB (rear Direct/front Geared motor 2WD)

Post by Alan B » Aug 21, 2016 8:05 pm

Good thoughts.

Here we have a CA plugged into a PhaseRunner. Both Grin products, their cables and connectors, etc, etc. Nothing homemade, crimped or soldered involved. Previously it was CA plugged into Lyen controller. Justin indicated at this voltage (66V) he had seen some break into oscillation, adding capacitance generally solved it. It seems fine with no load, it only goes nuts when the power gets higher, so I can't easily troubleshoot on the bench.

User avatar
Alan B
100 GW
100 GW
Posts: 7041
Joined: Sep 11, 2010 7:43 am
Location: San Francisco Bay Area, USA
Contact:

Re: Bonanza AWD eMTB (rear Direct/front Geared 2WD)

Post by Alan B » Aug 23, 2016 12:49 pm

Out with the Old

Image

Empty Triangle

Image

In with the New

New Luna 72V Battery

Image

A bit Small for this Frame Triangle

Image

This one fits a little better

Image

This triangle is a bit larger than either bag. Need to make it fit fairly well with the weight of this battery. Would be nice to do a custom triangle bag for it.

There's probably enough room for the support plate I was using before:

Image

Still need something to fill in the upper part of the triangle.
Last edited by Alan B on Aug 29, 2016 12:23 am, edited 1 time in total.

User avatar
Alan B
100 GW
100 GW
Posts: 7041
Joined: Sep 11, 2010 7:43 am
Location: San Francisco Bay Area, USA
Contact:

Re: Bonanza AWD eMTB (rear Direct/front Geared 2WD)

Post by Alan B » Aug 23, 2016 4:28 pm

Image

Perhaps use two of the (DX Engineering) tube clamps to support an aluminum flat bar 1" by 1/8" by 18" along the top of the bag? (flat bar not shown here but the clamps are at the ends, and the bar would be exactly on top of the bag...

The weight of the battery would be supported by the tubes underneath - the down and seat tubes, the top flat bar would only serve to prevent the pack from tipping to either side.

User avatar
Alan B
100 GW
100 GW
Posts: 7041
Joined: Sep 11, 2010 7:43 am
Location: San Francisco Bay Area, USA
Contact:

Re: Bonanza AWD eMTB (rear Direct/front Geared 2WD)

Post by Alan B » Aug 23, 2016 6:05 pm

Perhaps something like this:

Image

Hmm. Maybe I can mount the two PhaseRunner's in that space above the battery, still inside the triangle...

User avatar
Alan B
100 GW
100 GW
Posts: 7041
Joined: Sep 11, 2010 7:43 am
Location: San Francisco Bay Area, USA
Contact:

Re: Bonanza AWD eMTB (rear Direct/front Geared 2WD)

Post by Alan B » Aug 23, 2016 6:13 pm

Image

Plenty of room there for a couple of PhaseRunner's. :)

User avatar
Alan B
100 GW
100 GW
Posts: 7041
Joined: Sep 11, 2010 7:43 am
Location: San Francisco Bay Area, USA
Contact:

Progress Update, Two Motors Onboard

Post by Alan B » Aug 25, 2016 7:35 pm

Image

Maybe I should call it "Old Black and Blue"

Removed old Zokes forks, upper and lower bearing cups
Attempted to install crown race with PVC pipe, failed to install but managed to damage seal
Removed wheels
Stripped frame down to "non electric" for bike shop headset install
Headset crown race (with damaged seal) and bearing cups installed at bike shop (will either replace crown race later or not worry about it)
Surly fork installed (trial fit, steerer not cut)
Handlebars installed
Rear tire changed to Smart Sam matching front tire
Wheels reinstalled
Torque arms reinstalled
Front brake installed and adjusted (front disc screws too long, used a few shorter ones temporarily, need to replace those before use)

So how long should I make the steerer tube? I could keep it full length, and move the bars up further for a more relaxed riding position.

There's more to do, but it is almost rideable now..

User avatar
Alan B
100 GW
100 GW
Posts: 7041
Joined: Sep 11, 2010 7:43 am
Location: San Francisco Bay Area, USA
Contact:

Re: Bonanza AWD eMTB (Direct/Geared 9C/BMC 2WD)

Post by Alan B » Aug 26, 2016 11:34 pm

Image

The bike is taking shape

Installed red oak supports on the downtube and seat tube to provide better support for the triangle battery, and space it up away from the chainring and front derailleur.
Installed floor foam in the rear of the triangle battery bag to protect the wire exiting the battery
Installed the rear red LED light, a 12-100V unit from Ebikes.ca
Cable routing has begun, some are done
Top tube clamp has been retired in favor of a down tube clamp at the forward end of the battery to anchor the aluminum bar top support
Aluminum bar support on top of triangle bag needs some redesign
PhaseRunner mounting needs some redesign to fit in the smaller space
PhaseRunners will go in the triangle, in the space above the triangle pack
Wiring layout design has started, fine tuning it

User avatar
Alan B
100 GW
100 GW
Posts: 7041
Joined: Sep 11, 2010 7:43 am
Location: San Francisco Bay Area, USA
Contact:

Re: Bonanza AWD eMTB (Direct/Geared 9C/BMC 2WD)

Post by Alan B » Aug 28, 2016 11:12 am

Image

New triangle battery bag top retaining bar fabricated and installed with mounts for dual PhaseRunners
- this bar uses tie wraps rather than the large tubing clamps to mount it (sorry, hard to see in this photo, but the big tubing clamps are gone)
72V 17AH battery installed (bag is fairly full except for the left corner has some room
New m5x8mm screws installed in front disc
Cabling mostly present, starting to organize it (mostly after this photo)
Reinstalled the old CA, it has a problem measuring current but is all I have right now, CAv3s seem to be in short supply

Need to prepare the throttle cable with resistors and connectors for dual controller output (finished last night, not shown in this photo)
And make a power adapter / distribution cable to measure overall current and supply power to both PhaseRunners
The wiring mess will be a separate task for later, for now I'll just tiewrap it out of the way
Chain needs to be reinstalled as well
Reinstall mirror
May have to reprogram the CA, it was set up for current throttle control, it may interfere with throttle

The PhaseRunner heatsinking is not complete here, there will be more aluminum added on both sides which will also obscure the wiring and the PhaseRunners somewhat. Especially if that aluminum is painted black.

Eventually I want to re-cable and route the cabling through the bag and minimize the cabling. There is a lot of cabling on a 2WD bike!

I may also change the Red Oak for flat aluminum bar supports, and shorten them up. Will have to look at that.

Goal is to get it running today for some on road testing

User avatar
Wolfeman
100 W
100 W
Posts: 155
Joined: May 13, 2014 12:09 pm
Location: West Coast USA

Re: Bonanza AWD eMTB (Direct/Geared 9C/BMC 2WD)

Post by Wolfeman » Aug 28, 2016 11:51 am

Very cool build, thanks for posting. Looking forward to seeing more.
Trek 4300 w/ H3580 Crystalyte at 2300W
https://endless-sphere.com/forums/viewt ... =3&t=82738

User avatar
Alan B
100 GW
100 GW
Posts: 7041
Joined: Sep 11, 2010 7:43 am
Location: San Francisco Bay Area, USA
Contact:

Re: Bonanza AWD eMTB (Direct/Geared 9C/BMC 2WD)

Post by Alan B » Aug 28, 2016 12:03 pm

Image

Image

The extra wiring pile. :)

I used the glue-lined heatshrink on this throttle adapter, so the solder joints are protected from weather and bending. This shrink seals and glues everything together so it is pretty stiff through that section.

For this iteration we're taking a very simple approach. One major advantage of using the PhaseRunner controllers is the Torque Throttle input. With most regular controllers the input voltage from the throttle is converted to a particular PWM value which makes the motor want to turn a particular speed. Synchronizing the two motors then becomes a problem, and frequently there have been experiences of oscillations building under certain circumstances, or one motor dominating and the other doing essentially no work.

This is not the case with a Torque Throttle. A particular input voltage gets translated to a Torque, or Motor Current. The speeds can be whatever they need to be, coupled through the pavement, and the motors will automatically adapt to the speed. If one throttle gets a slightly higher or lower voltage due to the voltage drops in the wiring and the large currents flowing, this won't change the motor speed, it only changes the torque of that motor by a small amount. The battery currents will stabilize quickly. The system is not "sensitive" to small changes in throttle signals and will not have a tendency to want to oscillate. The motor Kv's don't need to match precisely, though it is nice if they are not too far apart, otherwise one will "spin out" at higher speed, though you could program its controller to shut it off in that case. If you drive a DD motor too fast it will start generating, which would be a problem, but a clutched motor can be dropped out like our front motor here. I plan to use a little field weakening on the DD motor to match the Kv values if necessary.

So a simple cable should work fine.

I may do something more complex and interesting later on, but start simple, and then improve...

There are other reasons for doing more complicated things with the throttle signal, and the main one is Justin's new "variable ebrake" and regen feature which is implemented in the PhaseRunner. From 0 to 0.8V is ebraking (maximum at 0). From 1 to 4V is throttle. So to get to the low voltages (and regen) will require fiddling with the throttle signal. I don't have regen controls on the bike yet so I'm not worrying about that at this point. During my PhaseRunner testing the regen didn't work so that requires investigation first anyway.
Last edited by Alan B on Aug 30, 2016 12:59 pm, edited 1 time in total.

User avatar
Alan B
100 GW
100 GW
Posts: 7041
Joined: Sep 11, 2010 7:43 am
Location: San Francisco Bay Area, USA
Contact:

Re: Bonanza AWD eMTB (Direct/Geared 9C/BMC 2WD)

Post by Alan B » Aug 28, 2016 12:11 pm

Wolfeman wrote:Very cool build, thanks for posting. Looking forward to seeing more.
Thanks for the comment. Point Reyes is not far away, it's been a long while since I've been out there. Are there some good ebike trails there?

User avatar
Alan B
100 GW
100 GW
Posts: 7041
Joined: Sep 11, 2010 7:43 am
Location: San Francisco Bay Area, USA
Contact:

Bonanza AWD Launched in 2WD Mode!

Post by Alan B » Aug 28, 2016 5:52 pm

Image

The Bonanza 2WD DoublePhaser is Up and Running!

I just returned from the maiden voyage. A solid 28 mph machine at 72V. (Battery at storage charge level)

Control is buttery smooth. It accelerates so smoothly you don't realize how fast it is going. Zooming at 25 mph up a steep hill is no problem. Low throttle allows gentle rolling along at walking speed, no jerky movement or sensitive throttle position required. This is a torque throttle, the way it should be.

I can hear a little gear noise in the front BMC motor. It is not loud, but I can tell it is working. I doubt if a bystander could hear it more than a few feet away. As I get into the upper range of the throttle at low speed I can hear the front tire fighting the pavement. At first I thought it was breaking traction, but it is not. It just makes a slight sliding noise at high torque, without fully sliding. It may be exacerbated by the Smart Sam tires, the torque may be leaning the knobs over a bit so they slide as they come off the pavement. I probably need to hook up two Cycle Analysts for a bit to see the power in each motor, and make some adjustments to the balance. During hard acceleration the front probably unloads a bit so it has less traction to work with. Really need to test in dirt.

None of the resonances that you get with trap controllers were observed. The 9C was totally silent. The BMC only made a little gear meshing noise. Eventually I will add a control on front/rear motors and we can go to silent "stealth" mode by dropping out the BMC.

Since the PhaseRunner has throttle voltage range adjustments, I can use that to fine tune the differential torque, as well as using the max motor current and max battery current of each controller. Lots of knobs. I have the phase currents set up quite high (default 80A), so probably need to tune those down a bit, at least in the front.

I'm not really hearing much of that funny noise that was in the BMC on the test stand. It may be there but not loud enough to hear very often, and I spent a lot of time at 10-15 where you can hear everything. I could not hear the clutch locking up, it is too smooth. I have a little extra ramping time set on the BMC controller to protect the clutch. I think the BMC will last much longer on a PhaseRunner than a standard trap controller because it is handled so much more smoothly.

The motors and the controller did not heat up at all in 4 miles, though I wasn't thrashing it this trip. The battery state was as shipped storage charge, so not full voltage.

The headset has a little play and needs to be tightened. This is normal for new headsets.

The brakes are good, the rear was mostly quiet but starting to want to screech again. I haven't worked on that. The Hayes front disc brake is working well, stopping is confident with just two fingers.
Last edited by Alan B on Aug 30, 2016 12:58 pm, edited 2 times in total.

User avatar
Alan B
100 GW
100 GW
Posts: 7041
Joined: Sep 11, 2010 7:43 am
Location: San Francisco Bay Area, USA
Contact:

2WD Equipment Recap

Post by Alan B » Aug 28, 2016 10:43 pm

2000 REI Novara Bonanza AL Two Wheel Drive Configuration

(Placeholder for now, this will be completed soon)

Front BMC 3TT laced in 26" Sun Rhyno Lite 36H Rim, 13-14 ga Sapim spokes, Ebikessf.com
Rear Nine Continents 2810 6x10 laced in 26" Sun Rhyno Lite 36H Rim, methods/jrh
Dual PhaseRunner BAC800+ controllers Ebikes.ca
Magura throttle and custom throttle cable, custom dual power cable
Luna 72V 17.5AH Battery, Charger and Triangle Bag, Lunacycle.com
Custom fabricated aluminum top bar battery bag support and PhaseRunner mount / Heatsink
Custom fabricated PhaseRunner Heatsinks
SRAM X.3 7 Speed Trigger Shifters
SRAM X.4 Rear Derailleur
xx original Front Derailleur
Triple Chainring original crankset and pedals, 28-38-44?
6 speed Freewheel 14-34 (change to 7?)
Cane Creek Forty Headset, 1 1/8" threadless
Original Handlebars and Riser Stem ?
Surly Big Dummy cromoly steel front forks
Dual torque arms front and rear (four total), Ebikes.ca
Axle Washer Stackups x including NordLock washers all 4 corners
Tires Schwalbe Smart Sam Plus HS367 26x2.25
Tubes thick thornproof front presta, thick slime rear schrader
Magura Throttle w/ 1K to +5, 1500 to ground on rear PR, throttle wire only to front PR
Cycle Analyst Ebikes.ca
Rear 8 Red LED Light 12-100V from Ebikes.ca
Mirrycle MTB Mirror
IncrediBell
Hayes 203mm front disc brake w/ M5x8 screws (BMC needs short disc screws)
Shimano XTR Rear rim brake (no disc mounts on frame)
REI 2000 Bonanza AL 7005 Heat Treated Aluminum Frame (19"?)
Thudbuster LT x diameter
Seat x
Topeak Rack
Last edited by Alan B on Sep 09, 2016 2:59 pm, edited 10 times in total.

User avatar
Alan B
100 GW
100 GW
Posts: 7041
Joined: Sep 11, 2010 7:43 am
Location: San Francisco Bay Area, USA
Contact:

Re: Bonanza Now AWD eMTB (Direct/Geared 9C/BMC 2WD)

Post by Alan B » Aug 28, 2016 10:44 pm

Was reviewing this thread for some information and came across early testing with the rear motor alone:

On a nearby Street (Brentwood), which is a 12-16% gradient,

The rear motor alone on 66V did 15 mph

The dual motor setup today on 72V did 25 mph!

User avatar
Alan B
100 GW
100 GW
Posts: 7041
Joined: Sep 11, 2010 7:43 am
Location: San Francisco Bay Area, USA
Contact:

Max Headset Spacer Height

Post by Alan B » Aug 29, 2016 11:46 am

Max Headset Spacer Height

Was checking the Surly website on what they recommend as the maximum height for headset spacers.

They said:
How many stack spacers can I use on my Surly fork?
Hey, go nuts. Seriously, these are beefy steel steer tubes. Geek out, stack 'er all the way up if you like.
So I think I will try that, at least to start with. That will give me some experience with higher bars and I can always cut it later.

User avatar
amberwolf
100 GW
100 GW
Posts: 24208
Joined: Aug 17, 2009 6:43 am
Location: Phoenix, AZ, USA, Earth, Sol, Local Bubble, Orion Arm, Milky Way, Local Group
Contact:

Re: Bonanza Dual PhaseRunner AWD eMTB (Direct/Geared 9C/BMC

Post by amberwolf » Aug 29, 2016 2:55 pm

You can even leave the steerer long and stick the bars/stem far down it (with spacers as needed under the cap), and use the steerer's extra length to clamp-mount "dash" stuff on, if you like. ;)

User avatar
Alan B
100 GW
100 GW
Posts: 7041
Joined: Sep 11, 2010 7:43 am
Location: San Francisco Bay Area, USA
Contact:

Re: Bonanza Dual PhaseRunner AWD eMTB (Direct/Geared 9C/BMC

Post by Alan B » Aug 29, 2016 3:13 pm

amberwolf wrote:You can even leave the steerer long and stick the bars/stem far down it (with spacers as needed under the cap), and use the steerer's extra length to clamp-mount "dash" stuff on, if you like. ;)
Yes - exactly - and I've seen folks mount a second stem under the handlebar stem and use it to mount stuff like a handlebar pack, or a great light bar perhaps. Lots of options!

For reference - I have nearly 4 inches of steerer tube extra, the original geometry had about 1" of spacers to the high rise stem, which is still in use.

I just stacked up all the spacers I have, minus a couple, and moved the stem to the top of the steerer. We'll see how that goes.

999zip999
100 GW
100 GW
Posts: 8226
Joined: Jan 10, 2010 1:40 pm
Location: Dana Point So. Cal

Re: Bonanza Dual PhaseRunner AWD eMTB (Direct/Geared 9C/BMC

Post by 999zip999 » Aug 29, 2016 6:41 pm

If 7sp or 6sp go with a dnp 34t-11t. Peddle power.
Edit 34t fat fingers.
Last edited by 999zip999 on Aug 29, 2016 11:52 pm, edited 1 time in total.

User avatar
Alan B
100 GW
100 GW
Posts: 7041
Joined: Sep 11, 2010 7:43 am
Location: San Francisco Bay Area, USA
Contact:

Re: Bonanza Dual PhaseRunner AWD eMTB (Direct/Geared 9C/BMC

Post by Alan B » Aug 29, 2016 7:15 pm

I've heard mixed reviews on the DNP, so far I've tried to stick with Shimano or SRAM, but they don't go below 13T.

How bad is the DNP, really?

999zip999
100 GW
100 GW
Posts: 8226
Joined: Jan 10, 2010 1:40 pm
Location: Dana Point So. Cal

Re: Bonanza Dual PhaseRunner AWD eMTB (Direct/Geared 9C/BMC

Post by 999zip999 » Aug 29, 2016 11:54 pm

11t 28.00usd. Have a 52t front but need a54t. Street model. Plus I ride the beach low tide.

User avatar
Alan B
100 GW
100 GW
Posts: 7041
Joined: Sep 11, 2010 7:43 am
Location: San Francisco Bay Area, USA
Contact:

Bonanza AWD Modelling

Post by Alan B » Aug 30, 2016 12:48 pm

Bonanza AWD Modelling

First of all, I want to start off with thanks to Justin for supplying the motor simulator and providing an excellent and important tool. I'm going to dig a bit and show some things in the Sim that are limitations and some are probably bugs, but understand that all software has limitations and bugs and that especially in sims we must be aware of them and work around them. So this is not a criticism of the simulator.

To keep it simple I'm not changing bike system weight, etc as the defaults are not too far off, and as long as they are the same that's fine. The less changed the easier to setup the sim. If you want to repeat this setup it is easy to do, just use the custom controller current values to get the currents, I even left the resistance at the default 0.03 for simplicity. I also selected the largest AllCell 72V and 36V packs. On to details.

Selecting the Motors, batteries, etc. The first problem I have is that neither of the motors I'm running are in the sim, and there's no way to add our own motor to the sim. So we have to find something close. In the BMC list there is a V2T, and I'm guessing it is very close to the V4TT that I have. The improvements to clutches, gears and heavier phase wiring won't make a huge difference to the motor performance. The 9C is a bigger problem. Even though the 9C 2810 motor I have is engraved with ebikes.ca (and apparently came from them, I bought it from ES:methods), it is not in the simulator. The best I can do is to use a 2805 and feed it half the voltage and double the current. One thing we need to keep in mind with this 2805 trick is that the motor current will be double that of the 2810, so anytime we look at B motor current we need to think "actually half of that value".

Choosing Battery Current - the Luna 72V pack BMS is rated for 50A continuous and 70A burst. I'm arbitrarily going to derate the continuous value by 10% and use 45 amps to provide a small margin. I've done quite a bit of modelling already so I'm going to choose 1/3 of that current to go to the front BMC gearmotor and 2/3 to go to the rear 9C DD. Remembering that the 9C we are using in the model runs at half voltage and double current, this results in 36V 60A to system B, while the System A value is 15A at 72V for a 45A total at 72V (half the 60 plus the 15 amps).

I was recommended by the BMC motor vendor (ilia of EbikesSF.com) to keep continuous power at or under 1300W. 72V fully charged is 84V times 15A is 1260W. So 15A is a safe value even at hot off the charger voltage. As we understand the 9C can handle a lot more power, and as we will see it needs more to keep up with (and exceed) the BMC.

The goal here with this 2WD setup is to have about the same thrust from each motor, preferrably a little more from the rear than the front.

In early riding of the 2WD Bonanza the front BMC was really providing a lot of thrust, apparently more than the rear. The initial values of battery current for the BMC were higher at 20A, and this made the BMC dominate the total thrust and made the front wheel want to spin. On pavement this resulted in noise from the tire but no slippage, in dirt the results could be bad, spinning out this wheel. We want it to pull, not spin. On to the settings:

Image

And then the good stuff:

Image

Now let's go through this and attempt to understand what it is telling us in detail. The graph above shows both motors in "full throttle" over the entire range of speed from 0 to 50 mph. My apologies to the metric folks. Torque is in Nm so we are mixing modes and annoying everyone a bit. At any rate, values to the left of the equilibrium point, which is 29.1 mph for the BMC, and a little less for the 9C are in the acceleration region, and values to the right are not going to happen, except after a big hill as we decelerate back to equilibrium on the level. Equilibrium occurs when the load line crosses the motor power line, so when the power and the losses are the same. From experience I can say that this is a 28 mph machine at 72V, so these values are in the right neighborhood.

This graph looks fairly well matched, if we look at torque from both motors (the blue lines), the BMC starts out higher, at 6 mph the 9C takes over, and at 27 the BMC again takes over as the back EMF from the 9C reduces its power. We want the 9C to have greater torque all across the curve, so we'll be making adjustments to accomplish that. Now what about that crazy stuff at very low speed?

Now we need to understand that the simulator is a complicated piece of software and it doesn't take everything into account, and there are always some bugs in software. We need to always be on the lookout for simulator anomalies, and we have some here.

If we look at 0.5 mph (if you run the sim and click on it you can get to these values in the boxes) we see the BMC battery current is 15 amps, as we requested. However at 1.1 mph the battery current is 27.8 amps, almost double what we requested the limit be. This makes the crazy 145 Nm torque value shown. We don't want this torque level on the BMC, it might break clutches and gear teeth, and the PhaseRunner controllers are very good at controlling actual motor current (which trap controllers generally are poor at doing). In fact, at these very low speeds we don't even want the full 15 amps of battery current since the current multiplication of the controller could produce more motor current and torque than we want. So we set a motor phase current limit in the PhaseRunner. But what value?

We know the 9C has a knee in the torque curve at about 468 ampere turns, right at 70 Nm, where the efficiency starts to fall off somewhat. Justin measured this in a thread:
https://endless-sphere.com/forums/viewt ... 4&start=25

If we look at 70 Nm that shows about 90A for the 2805 motor in the sim, so it will be about 45-47A for the 2810 that I have. You can drive more current than this, but the efficiency is reduced, and Justin was finding that even at this level the motor and phase wiring was heating up a lot. So this is a good value for the max torque, or slightly higher if you want more torque and don't mind losing a tiny bit of efficiency and heating the motor a bit (as long as it is only for short periods). Perhaps we should choose 50 amps just for a round number as the 9C 2810 max motor current. Pushing on the pedals will increase the rear wheel torque a lot at these low speeds as well. I've found it is easy to pedal the rear wheel to spin in steep dirt situations.

Since the Kv of these motors is nearly matched (The PhaseRunner measured 5.5 for the BMC and 5.3 for the 9C) that means the Kt torque constants are also nearly matched (since they are reciprocally related constants). This means the BMC produces slightly more speed per volt and slightly less torque per amp, the difference to this 9C being about 5%. So we want the motor current limit for the BMC to be a bit lower than the 9C to keep the BMC torque lower. If we make the current the same the BMC torque will be about 5% lower, and we want it even a bit lower yet, so let's make the BMC max motor phase current be 45A, so the BMC torque will be about 15% reduced compared to the 9C.

So what will that do to this graph? The lower part of the torque curves will flatten out from zero speed to where they start dropping naturally, with the 9C at about 70 Nm and the BMC at about 60 Nm. Pretty good hill climbing power without overstressing the BMC gear and clutches and without heating the 9C too fast. With 2WD each motor only has about half the load to deal with.

Now at the high end of the speed range, around 27 mph, the BMC and 9C torque curves cross again. We don't want the BMC torque to rise above the 9C torque at high speed. ilia was concerned about this and suggested that the BMC be shut off at high speeds. We could easily do that, but we have another choice with the PhaseRunner controllers - to use Field Weakening to reduce the back EMF of the 9C a bit and push it harder at the high speed end. Not to go faster, but to balance the torque. The simulator won't handle field weakening, so we'll have to experiment. Perhaps we will shut the BMC off at 28.

I'm going to install a pair of Cycle Analysts so I can look at both motors as these adjustments are fine tuned. I can use a chest mounted GoPro to record the data so I don't have to look away from the road too long, and can ride on various gradients and see how the power balances. It doesn't have to be a perfect balance but we don't want any surprises or PhaseRunner trips.

Some have asked me about the motor speeds being matched and what happens when they are not with a 2WD ebike. With a pair of trap controllers being fed the same throttle signal you do want matched tire speeds, so the Kv should be equal (equal speed, so tire size could be used to make up for differences in Kv). Here we have two PhaseRunner Field Oriented Controllers that take the throttle signal as a torque request. This compensates for speed automatically so the motor Kvs don't need to match at all. If you dial to 50% throttle each controller will work to produce 50% torque, automatically compensating for the speed of the wheel. It is a nearly ideal setup and is one of the reasons I decided to use dual PhaseRunners on this project. They are also a lot smaller and easier to place on the bike, and they have fewer wires than the usual trap controllers.
Last edited by Alan B on Aug 30, 2016 7:26 pm, edited 1 time in total.

User avatar
amberwolf
100 GW
100 GW
Posts: 24208
Joined: Aug 17, 2009 6:43 am
Location: Phoenix, AZ, USA, Earth, Sol, Local Bubble, Orion Arm, Milky Way, Local Group
Contact:

Re: Bonanza AWD Modelling

Post by amberwolf » Aug 30, 2016 2:14 pm

Alan B wrote:I'm going to install a pair of Cycle Analysts so I can look at both motors as these adjustments are fine tuned. I can use a chest mounted GoPro to record the data so I don't have to look away from the road too long, and can ride on various gradients and see how the power balances.
How about a serial data recorder? A laptop (or other device) with two serial ports (or two USB-serial converters) running a logging-terminal program would write the data to a file, that you could then sort thru the data later for the specific stuff you're after. Much easier than going thru a video and noting things down, I'd expect.

Adafruit (and other places) also make simple serial loggers like this one
https://www.adafruit.com/product/2796
but I don't know that it would be worth buying stuff you may not already have laying around just for the one test. (unless you might want to be doing this sort of thing often enough to justify the expense).

User avatar
Alan B
100 GW
100 GW
Posts: 7041
Joined: Sep 11, 2010 7:43 am
Location: San Francisco Bay Area, USA
Contact:

Re: Bonanza Dual PhaseRunner AWD eMTB (Direct/Geared 9C/BMC

Post by Alan B » Aug 30, 2016 2:26 pm

That would be a good solution.

It would need to be a dual serial recorder to pick up both CA outputs. Also the PhaseRunners have serial data out, but that would require two laptops to capture since their software seems to handle only one.

I'm a little reluctant to carry a laptop onboard, a small spill could do a lot of damage. But it would be nice to have the data.

I have a little serial capture board with SD card, but it only takes one serial stream. The capture should be synchronized to get both streams at once.

I think I can get a lot of what I need just visually from two CA displays. But recording video would give some review ability. Plus I have the GoPro and chest harness. I've recorded a lot of boring commute video, I just never publish it -- too boring.

I can say that after having test ridden this setup that a pair of FOC torque throttle controllers is what your trike needs to stop the throttle steering problem. I don't know if the PhaseRunner is big enough for your motors, perhaps you need two BAC2000's. The low cost sinewave controllers don't have torque throttle, that is key to allowing the motors to seek their own speed regardless of Kv.

User avatar
amberwolf
100 GW
100 GW
Posts: 24208
Joined: Aug 17, 2009 6:43 am
Location: Phoenix, AZ, USA, Earth, Sol, Local Bubble, Orion Arm, Milky Way, Local Group
Contact:

Re: Bonanza Dual PhaseRunner AWD eMTB (Direct/Geared 9C/BMC

Post by amberwolf » Aug 30, 2016 3:08 pm

Back when my CA v3 still worked, I had planned to carry an old laptop in my CrazyBike2's metal side cargo pod, padded with chilled (but not frozen) gelpacks to both keep ti from vibration/bumps and absorb it's heat, but I didn't get that far before various events got in the way.

I was also going to test out an old serial-port-type PDA and see if that would also work, but I hadn't found a datalogging app at the time.

Nowadays I would probably see about using an old android tablet or phone for it, if serial input devices for USB on PC's could be adapted to them, and datalogging apps exist. At least no risk to harddisk crash from impact or vibration in those. (though one can also use a USB stick to run a laptop from, and remove it's harddisk--might end up more practical as I have a few very old laptops that might work that way).


For the trike's wheels, I actually use the separate throttles to steer it in turns a fair bit, but it would be nice to just be able to use a single throttle to control both wheels under most cruising, and override it only in sharp turns.


Thanks to Justin's generosity some time back, I've got one of the original 500w ASI controllers (in the silver angular metal package), from Justin's bike on the Maker Faire trip, that I have experimented with a bit but so far haven't gotten it actually running any motors (lack of time mostly). I intend to try it eventually (someday) just to see how it works on the trike vs the regular controllers.

But a pair of PRs or the bigger BACs is well out of any budget for the foreseeable future. Still dreaming on that one, along with a lot of other things. :)

User avatar
Alan B
100 GW
100 GW
Posts: 7041
Joined: Sep 11, 2010 7:43 am
Location: San Francisco Bay Area, USA
Contact:

PhaseRunner Heatsinks

Post by Alan B » Aug 31, 2016 4:39 pm

Image

Image

Made a pair of heatsinks for the PhaseRunners today. Over 16 square inches of 1/8" thick aluminum exposed to airflow on each PhaseRunner. I don't know that they will be needed as they have run cool thus far, but they provide some mechanical protection and will help hide the wiring, especially if they are painted black.

I'm thinking a small custom nylon bag to enclose the extra wire might be handy also. Keep it clean and less visible. I'm hoping to submerge the wiring into the battery bag to some degree when I shorten the excess cable. But function comes first.

Great way to finish the page, see you all on the next page!
Last edited by Alan B on Aug 31, 2016 9:17 pm, edited 2 times in total.

Post Reply