Motorboard project

Lightweight / Folding / Portable EVs - seats optional

Motorboard project

Postby Stielz » Thu May 26, 2011 7:21 pm

Hi everyone,

I thought that it would be a good idea to share the progress of this project on this forum.
It looks like there are a lot of members who are experts on this sort of thing so any suggestions, comments, criticisms, and questions are welcome.

The project:
The project is to build a motorised mountain board. I will be building a custom made motor controller with forward, reverse, breaking, and coasting modes. The motor driver will be controlled by the C8051 microcontroller. This will allow me to include many useful functions such as:

- Battery level monitoring
- Power usage
- speed and distance monitoring
- LCD display
- cruise control
- soft start
- motor controller and motor overheating shut down
- plus any other suggestions?

This build differs form existing products (for example http://greenskate.co.nz/specifications-and-features/) in that:
a) The electric skateboard is 1 wheel drive (and 1 wheel breaking) whereas my motorboard will be 2WD.
b) It will have much more power. The electric skateboards are generally no so good on hills. The aim for my motorboard is to be able to go 50 km/h up hills and off road
c) It will have the motor mounted off the back of the rear axle and batteries and motor controller mounted on top of the board to that it doesn't have a undercarriage like the electric skateboard does. This will make it more off road.
d) the electric skateboard costs $1,585 NZD whereas my motor board will cost about $800 NZD to build (not including countless hours of my time)

Parts:

The mountain board:
weight = 6 kg

CIMG0071.JPG
Mountain Board
CIMG0071.JPG (166.89 KiB) Viewed 8264 times



The motor:
BLDC outrunner (Turnigy C80 100 130). This was chosen mainly due to the low kv value which means less gearing is required. A 1:3.5 gear ratio should give a speed of about 50 km/h
for specs see http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=5142
And yes I know it is overkill for this application. The way I see it is its better to power and not need it than to need it and not have it. Plus because I am building my own motor controller, I can very easily limit the current and therefore the power to the motor.

CIMG0073.JPG
Motor
CIMG0073.JPG (100.96 KiB) Viewed 8362 times



The microcontroller:
Silicon Labs C8051F020
for specs see http://www.silabs.com/products/mcu/mixed-signalmcu/Pages/C8051F02x.aspx
The reason I will be using this model is that we have these ucontrollers available at university. If I end up having to buy one to keep I will choose a model that is more specialised for motor control

The motor driver:
I will build a 3 phase H-bridge with IRF3205 N-channel MOSFETS. These are capable of 70A continuous at a max voltage of 55V. The motor driver will have 3 of these paralled to make a 210A continuous current motor driver.

Batteries:
I have ordered 4 Turnigy 5s 5000mAh 20C batteries. They will be connected in 10S2P configuration to make a 36V, 10 Ahr battery (360 Whr) that can supply 200A continuous or 300A bursts. Ideally I would have more battery power but cost is an issue.
for specs see: http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=9174


More progress updates to come shortly.
Last edited by Stielz on Fri May 27, 2011 6:09 am, edited 1 time in total.
User avatar
Stielz
100 W
100 W
 
Posts: 239
Joined: Fri May 20, 2011 11:54 pm
Location: Wellington, New Zealand

Re: Motorboard project

Postby sk8norcal » Thu May 26, 2011 7:33 pm

cool, cant wait to see the finished product,

http://wackyboards.blogspot.com/search/ ... c%20boards
Last edited by sk8norcal on Thu Nov 17, 2011 2:16 am, edited 1 time in total.
User avatar
sk8norcal
10 GW
10 GW
 
Posts: 4295
Joined: Sun May 16, 2010 5:29 am
Location: San Jose, CA

Re: Motorboard project

Postby liveforphysics » Thu May 26, 2011 7:51 pm

Stielz wrote:The motor driver:
I will build a 3 phase H-bridge with IRF3205 N-channel MOSFETS. These are capable of 70A continuous at a max voltage of 55V. The motor driver will have 3 of these paralled to make a 210A continuous current motor driver.



I'm guessing this is because you just happened to have a pile of these crap FETs laying around or something?

With any 1-off controller build, parts cost won't even be 1% of the labor costs involved. Do yourself a favor and use good parts.

Especially in an application where that motor's ultra-low phase resistance and inductance make pretty tough to control multi-hundred amp transients in even the best high speed controller designs.
Ebikes.ca

My bicycle completes the standing quarter mile in 11.502seconds at 110.56mph.

Giving my time to the electric revolution is done with pleasure. It is no longer fashionable to spit carcinogenic combustion by products in peoples faces as a part of sating daily transport.

Every post is in honor to the free idea exchange that Justin le preserved to grow with an amazingly high quality content in what is the living bleeding edge of LEV development.
User avatar
liveforphysics
100 GW
100 GW
 
Posts: 13953
Joined: Wed Oct 29, 2008 1:48 am
Location: Santa Cruz, CA, USA

Re: Motorboard project

Postby Stielz » Thu May 26, 2011 11:20 pm

would you have two motors, one for each rear wheel ?


No I wont be using 2 motors, that will involve having two motor controllers also. I will either:
a) make a live axle for it so that I only have to drive one wheel which will then drive the other, or
b) make a new shaft for the motor that is slightly longer and protrudes out each end of the motor an equal distance. then I can drive one wheel off each end of the motor.

I think the second option will be easier. I have seen videos etc of the turnigy C80100 130 motor being taken apart and it looks reasonably simple to swap the shaft for a longer one.
The motor will be mounted via external bearings on the shaft to take the load off the apparently weak internal bearings.

I'm guessing this is because you just happened to have a pile of these crap FETs laying around or something?

With any 1-off controller build, parts cost won't even be 1% of the labor costs involved. Do yourself a favor and use good parts.


The reason I got these FET's is that someone was selling a bunch of them on Trade Me (New Zealands version of E-Bay) for a very cheap price.
Because I already have them, I will see how the motor controller goes with them and if its a problem then I will look at getting some good ones.

Here is the output of a MATLAB model I made to help with determining power requirements, battery requirements, etc.
The model predicts either the power required or distance on a single charge as a function of speed and slope.
The model takes into account: acclerations, air drag, rolling resistence, and power to gain height

Power requirements.jpg
Predicted power requirements
(101.15 KiB) Downloaded 5 times

distence prediction.jpg
Distance predictions
(107.72 KiB) Downloaded 5 times


The input variables I used for the model are:
V = 36; %battery voltage
C = 10; %battery capacity (Amp hours)
p = 1.2; %fluid density (kg/m^3)
A = 0.5; %Front area of person (m^2)
Cd = 0.9; %drag coefficient of person
m = 85; %total mass (kg)
em = 0.80; %motor efficiency
ed = 0.97; %drive efficiency
Cr = 0.05; %coefficient of rolling resistance (on road)
nc = 3; %number of starts from complete stop
np = 5; %number of starts from patrial stops (25% of nominal speed)

I'm not sure how accurate some of these estimates are. Anyone have suggestions for improvement?
User avatar
Stielz
100 W
100 W
 
Posts: 239
Joined: Fri May 20, 2011 11:54 pm
Location: Wellington, New Zealand

Re: Motorboard project

Postby nieles » Fri May 27, 2011 3:49 pm

with the two wheels mechanicaly coupled it will be very hard to steer. have you thought about that?

3 solutions;

1. only drive on wheel
2. use some sort of differential
3. use two motors (not connected to each other)
nieles
10 kW
10 kW
 
Posts: 611
Joined: Mon Jul 14, 2008 5:39 pm
Location: The Netherlands

Re: Motorboard project

Postby adrian_sm » Fri May 27, 2011 5:33 pm

Motor efficiency obvisouly changes with load, so 80% will be optimisitic when going up hills etc.

There a a few impressive mountain board builds on here. HumboldtRc's build is the one that comes to mind, but search around for others.

Here his thread on the hoobyking forum about it.
http://www.hobbyking.com/hobbyking/foru ... 12064&PN=1

Good luck,
Adrian
Build #1 ~28kg ~ 700w Avanti Hardtail Crystalyte 408, 48V10Ah Headway. ~5500 kms to date. (retired)
Build #2 ~30kg ~2000w Giant AC Dually Crystalyte 408, 48V10Ah Headway + 6s10Ah LiPo = 70V. ~15000 kms to date [SOLD]
Build #3 ~13kg ~2000w Commuter Booster <1kg Friction Drive in Beta testing (www.commuterbooster.com)
Build #??? ~21kg ~1500w Adrian's Bafang BPM Hardtail MTB Bafang BPM code12, 15s LiPo, ~40kph, ~30kms
User avatar
adrian_sm
100 MW
100 MW
 
Posts: 2642
Joined: Mon Feb 23, 2009 12:54 am
Location: Melbourne, Australia

Re: Motorboard project

Postby Stielz » Fri May 27, 2011 7:12 pm

with the two wheels mechanicaly coupled it will be very hard to steer. have you thought about that?


I have thought of that, I just thought that one of the wheels would slip without too much problem.. This may not be the case on road however.
The board is aimed more towards off-road applications so 1 wheel drive isn't really an option; it will be struggling to find traction (not saying it wont be struggling to find traction in 2WD with the 6.5kW motor :D ).

If I drive one wheel off each end of the motor then switching from 1WD to 2WD will be as easy as taking off a drive belt/chain so perhaps that will be a good option to go for if I want to be able to cruise on roads as well.

I have been wondering about these 1WD models, do they pull to the side when you hit the accelerator or break?

HumboldtRc's build is a very nice example, that is what inspired me to build one. 4WD would be awesome, that could possible be a future upgrade for my build. Anyway, I wont get too far ahead of myself and stick with the plan for now.

Thanks for all the tips guys
User avatar
Stielz
100 W
100 W
 
Posts: 239
Joined: Fri May 20, 2011 11:54 pm
Location: Wellington, New Zealand

Re: Motorboard project

Postby Stielz » Sat May 28, 2011 11:19 pm

After taking the motor apart I found all the usual quality issues that these motors have.

There is a brroken wire in one of the windings:
CIMG0082.JPG
Broken wire
CIMG0082.JPG (75.83 KiB) Viewed 8266 times


Some of the wires have slack and could come out of the winding gap and wreak havoc.

The glue holding the magnets on looks to be fine though, I guess they must have fixed that problem.

I am wondering if spraying it with a coat of clear enamel spray paint will be a good idea? That could stop the iron laminates from rusting and hold all the wires in place.

Next step: install the hall sensors.
There is a very helpful thread on this topic at http://endless-sphere.com/forums/viewtopic.php?f=30&t=15686&hilit=c80100+130
Cheers for that Burtie
Last edited by Stielz on Mon May 30, 2011 2:52 am, edited 1 time in total.
User avatar
Stielz
100 W
100 W
 
Posts: 239
Joined: Fri May 20, 2011 11:54 pm
Location: Wellington, New Zealand

Re: Motorboard project

Postby AussieJester » Sun May 29, 2011 12:24 am

You can buy lacquer in a can that is designed for electrical motor windings
straight enamel spray paint will burn. I have had motors with fiberglass resin
holding the windings, this works but damn it smells bad, i would definitely get the
electrical winding spray. Coventry Fastners sell it if you have one in Kiwi land forget
the brand soz..

KiM
User avatar
AussieJester
100 GW
100 GW
 
Posts: 9444
Joined: Tue Mar 11, 2008 3:33 am
Location: Perth Western Australia

Re: Motorboard project

Postby only1jake » Mon May 30, 2011 2:47 am

Hey Burtie!
Looks really awesome and should turn out pretty well!
What top speed are you looking at? Thought of gearing ratios?

Oh and by the way, come check out http://ev.geek.nz/ and share your project and ideas. :mrgreen:
(It's a New Zealand ev forum, fairly new)

Jake
Jake Saunders
User avatar
only1jake
100 W
100 W
 
Posts: 223
Joined: Tue Sep 29, 2009 4:22 am

Re: Motorboard project

Postby Stielz » Mon May 30, 2011 6:32 pm

Im thinking a top speed of 50 km/h would be nice, whether or not I will want to go that fast is another story.

Going by the theoretical speed of the motor of 4680 RPM at 36V, a gear ratio of 3.5:1 should give a top speed of 50 km/h.

I have been wondering how much the load will effect the top speed of the motor. I'm assuming that it wont reach 4680 RPM when it is under load. Can anyone offer advise on how much the theoretical top motor speed is likely to reduce as a function of load? I have not been able to find any technical data for this motor (Turnigy C80100 130). A torque-speed graph would be nice.
User avatar
Stielz
100 W
100 W
 
Posts: 239
Joined: Fri May 20, 2011 11:54 pm
Location: Wellington, New Zealand

Re: Motorboard project

Postby adrian_sm » Mon May 30, 2011 10:29 pm

Here is a rough power required for a bike to travel at various speeds.
Image

Then you need to overlay the power that your motor can output. This will provide peak power at half the no load speed, and be zero at 0 rpm, and full no load rpm. Were the curves cross is roughly your cruise speed on the flat.

- Adrian
Build #1 ~28kg ~ 700w Avanti Hardtail Crystalyte 408, 48V10Ah Headway. ~5500 kms to date. (retired)
Build #2 ~30kg ~2000w Giant AC Dually Crystalyte 408, 48V10Ah Headway + 6s10Ah LiPo = 70V. ~15000 kms to date [SOLD]
Build #3 ~13kg ~2000w Commuter Booster <1kg Friction Drive in Beta testing (www.commuterbooster.com)
Build #??? ~21kg ~1500w Adrian's Bafang BPM Hardtail MTB Bafang BPM code12, 15s LiPo, ~40kph, ~30kms
User avatar
adrian_sm
100 MW
100 MW
 
Posts: 2642
Joined: Mon Feb 23, 2009 12:54 am
Location: Melbourne, Australia

Re: Motorboard project

Postby EDS » Thu Jun 02, 2011 10:44 pm

I recently motorized my carveboard (I've been meaning to post some info). Mine is 1wd. You can't feel it pulling to the side at all. However, if the drive wheel hits a patch of leaves or gravel while leaned into a turn, it will slide out violently immediately - at least with slicks on road; off road with knobbies should be more forgiving. I'd definitely go with 2wd for off road.  You probably don't need a diff. You'll have positraction without it which will probably help with traction more than a diff would help with steering. A board has a narrow track, so the inside & outside wheels turn on almost the same arc anyway.  An adjustable diff would be cooler though. You could try using 1/8 scale rc parts.  Whatever you try, post how i works out. 

That motor and battery combo will drive a board as fast as you want it to go. Pick a few gear options in the range you're interested in & after you try it out, gear it as tall as your balls are large.  Board speed feels about twice as fast as the same speed on a bike. I've only wrecked once so far but it felt like a bike wreck from about twice the speed.  Low gearing will reduce the chance of blowing your controller when you're crawling up a hill off road. 

I'm using the much smaller 63-64 on 6s and it will go over 20mph, has >10 mi range on 3p of the same cells, and climbs paved hills without slowing down much.

Good luck.     
EDS
1 mW
1 mW
 
Posts: 18
Joined: Sun Jan 09, 2011 8:15 pm

Re: Motorboard project

Postby Stielz » Sat Jun 04, 2011 2:40 am

Thanks for the reassurance. I see what you mean with the diff idea, without a limited slip diff it probably wont be much better than having 1WD. I would be interested to see more info on your build.

Anyway, just a quick progress update:

I have installed hall sensors in the motor now - an internal setup with the sensors spaced 120 degrees apart (every fourth slot in the stator windings).

To make thing more interesting, I have installed two sets of halls; one for neutral timing and one for 30 degree advanced/retarded timing (depending on what direction the motor is running). This will allow me to play around with switching between neutral timing and advanced timing for low and high motor speeds respectively.

It turns out that a 30 degree offset between the sets of halls is very useful because it allows me to generate a signal for a -30 degree set based on the other two. So I will be able to run the motor with 30 degree retarded, neutral, and 30 degree advanced timing in both directions.

The halls are just held in with blu-tack and tape at the moment so that I can fine tune the position of the sensors if required. From what I hear, the relative spacing in very important in maximising the efficiency of the motor
User avatar
Stielz
100 W
100 W
 
Posts: 239
Joined: Fri May 20, 2011 11:54 pm
Location: Wellington, New Zealand

Re: Motorboard project

Postby Stielz » Tue Jun 07, 2011 2:47 am

I got a chance to have a look at the hall signals on the scope today, everything looks to be in order. I'm not sure why the 30 degree offset signals are inverted however. No problem though, they can easily be inverted again in the microcontroller.

photo 2.JPG
hall signals
photo 2.JPG (56.11 KiB) Viewed 8073 times


I have also made up a prototype for the motor driver circuit; Gate driver IC is on the breadboard and the FETs on the veroboard so I can put some reasonable current through it. the tracks have been beefed up with solder. Should be able to do 70A continuous when I get some heat sinks on it.

photo 1.JPG
Driver prototype
photo 1.JPG (107.26 KiB) Viewed 7975 times


Thats all the hardware I need for the basic prototype, now to focus on developing the microcontroller program.
User avatar
Stielz
100 W
100 W
 
Posts: 239
Joined: Fri May 20, 2011 11:54 pm
Location: Wellington, New Zealand

Re: Motorboard project

Postby Stielz » Thu Jun 09, 2011 12:54 am

I'm trying to decide whether to go with a belt or chain drive. Chain drive seems to be the popular choice for this type of EV.

Can anyone offer any advice on the pros and cons of belt and chain drives?

The only problem I an think of with a belt drive is that it could get stones etc in between the belt and pulleys which could damage the belt.
User avatar
Stielz
100 W
100 W
 
Posts: 239
Joined: Fri May 20, 2011 11:54 pm
Location: Wellington, New Zealand

Re: Motorboard project

Postby EBJ » Fri Jun 10, 2011 1:39 pm

With that much power your belt would need to be very wide (and it would likely still skip under hard acceleration). Chain is the best bet. #25 chain might be too small for this much power, so consider 8mm.
EBJ
1 kW
1 kW
 
Posts: 387
Joined: Thu Jun 09, 2011 11:29 am
Location: Berkeley

Re: Motorboard project

Postby liveforphysics » Fri Jun 10, 2011 2:00 pm

Stielz wrote:I got a chance to have a look at the hall signals on the scope today, everything looks to be in order. I'm not sure why the 30 degree offset signals are inverted however. No problem though, they can easily be inverted again in the microcontroller.

photo 2.JPG


I have also made up a prototype for the motor driver circuit; Gate driver IC is on the breadboard and the FETs on the veroboard so I can put some reasonable current through it. the tracks have been beefed up with solder. Should be able to do 70A continuous when I get some heat sinks on it.

photo 1.JPG


Thats all the hardware I need for the basic prototype, now to focus on developing the microcontroller program.



Looks like you've got some skills. :) Right on!


If you're switching FETs straight from the uController, you're going to want to put a good FET driver in between in a big way. When you say 70amps, be aware battery current is not phase current, and the only current the FETs see is phase current, which it doesn't look like you've got a means to measure on that board. On a motor like this with low inductance and resistance, 70amps of battery current at low RPMs can be trying to put 500amps of phase current (it will vary at the inverse of the duty cycle percentage). This is why I made the comment about starting with the best possible FETs to begin with, because you will soon find what happens when that motor feels a little load at low RPMs and only watching battery current. :) FET plasma surprise. :)
Ebikes.ca

My bicycle completes the standing quarter mile in 11.502seconds at 110.56mph.

Giving my time to the electric revolution is done with pleasure. It is no longer fashionable to spit carcinogenic combustion by products in peoples faces as a part of sating daily transport.

Every post is in honor to the free idea exchange that Justin le preserved to grow with an amazingly high quality content in what is the living bleeding edge of LEV development.
User avatar
liveforphysics
100 GW
100 GW
 
Posts: 13953
Joined: Wed Oct 29, 2008 1:48 am
Location: Santa Cruz, CA, USA

Re: Motorboard project

Postby Stielz » Sun Jun 12, 2011 4:24 am

Thanks for the advice guys,

I am using a gate driver IC between the uController and FETs and I have a current sensor IC on the way.
I was planning to have the current sensor between the lower FETs and GND, would this be sensing the phase current on whichever phase pair is in use at any instant, or would it be sensing the battery current?
User avatar
Stielz
100 W
100 W
 
Posts: 239
Joined: Fri May 20, 2011 11:54 pm
Location: Wellington, New Zealand

Re: Motorboard project

Postby parabellum » Thu Jun 23, 2011 12:40 am

Stielz wrote:Thanks for the advice guys,

I am using a gate driver IC between the uController and FETs and I have a current sensor IC on the way.
I was planning to have the current sensor between the lower FETs and GND, would this be sensing the phase current on whichever phase pair is in use at any instant, or would it be sensing the battery current?


If you sense current on 1 of 3 phases (directly in between controller and motor), isn't it accurate enough?
User avatar
parabellum
1 MW
1 MW
 
Posts: 1782
Joined: Fri Nov 19, 2010 9:55 am
Location: Dominican Republic, north.

Re: Motorboard project

Postby Stielz » Thu Jun 23, 2011 5:43 am

Its not accuracy that is the issue here, its a matter of being able to sense the current at any instant as I will attempt to explain...

There are 6 commutation sequences in an electrical cycle and each phase is active (either switched to +V or GND) for 4/6 of these sequences. So there are 2/6 sequences in which there is no current flowing in a given phase (when the phase is left floating).

My concern with having the current sensor is on one of the phases is that when the motor is stalled or just starting up, the rotor could be in a position such that the phase with the current sensor is the floating phase. In this case, the uController would be seeing no current when the current in the other two phases could actually be very high.

If the current sensor is positioned between the lower FETs and GND, then it will sense the current on whichever phase pair is active and therefore will be able to sense the current at any instant.

However, I still don't quite understand the previous post:

If you're switching FETs straight from the uController, you're going to want to put a good FET driver in between in a big way. When you say 70amps, be aware battery current is not phase current, and the only current the FETs see is phase current, which it doesn't look like you've got a means to measure on that board. On a motor like this with low inductance and resistance, 70amps of battery current at low RPMs can be trying to put 500amps of phase current (it will vary at the inverse of the duty cycle percentage). This is why I made the comment about starting with the best possible FETs to begin with, because you will soon find what happens when that motor feels a little load at low RPMs and only watching battery current. FET plasma surprise.


I can see that if a capacitor is used between the +V and GND terminals of the motor controller then the current between the battery and the cap will be the average phase current. However if the current sensor was between the cap and the FETs would that not still be the phase current? (on whichever phases are active at any time)
User avatar
Stielz
100 W
100 W
 
Posts: 239
Joined: Fri May 20, 2011 11:54 pm
Location: Wellington, New Zealand

Re: Motorboard project

Postby parabellum » Thu Jun 23, 2011 8:28 am

parabellum wrote:However, I still don't quite understand the previous post:

If you're switching FETs straight from the uController, you're going to want to put a good FET driver in between in a big way. When you say 70amps, be aware battery current is not phase current, and the only current the FETs see is phase current, which it doesn't look like you've got a means to measure on that board. On a motor like this with low inductance and resistance, 70amps of battery current at low RPMs can be trying to put 500amps of phase current (it will vary at the inverse of the duty cycle percentage). This is why I made the comment about starting with the best possible FETs to begin with, because you will soon find what happens when that motor feels a little load at low RPMs and only watching battery current. FET plasma surprise.



I can see that if a capacitor is used between the +V and GND terminals of the motor controller then the current between the battery and the cap will be the average phase current. However if the current sensor was between the cap and the FETs would that not still be the phase current? (on whichever phases are active at any time)


Rhitee05 took a very serious approach on phase current measurement (and limiting) here.
viewtopic.php?f=2&t=28935&start=30
I know, he is working outside the controller on a kind of add on tool, but I think it still can be interesting for you.
User avatar
parabellum
1 MW
1 MW
 
Posts: 1782
Joined: Fri Nov 19, 2010 9:55 am
Location: Dominican Republic, north.

Re: Motorboard project

Postby parabellum » Thu Jun 23, 2011 8:32 am

Lol, there is some kind of error on my quote, it said "parabellum wrote" :D
User avatar
parabellum
1 MW
1 MW
 
Posts: 1782
Joined: Fri Nov 19, 2010 9:55 am
Location: Dominican Republic, north.

Re: Motorboard project

Postby fechter » Thu Jun 23, 2011 2:49 pm

Most cheap controllers have a single current sensor between the cap and the FET low side supply rail. This seems to work OK for most applications as long as the limit is set properly.

Battery current will equal phase current only at 100% duty cycle. At less than 100%, the phase current will be higher as the collapsing magnetic field is circulated by the freewheel diode (or FET used for synchronous rectification). During startup and other low duty cycle periods, the phase current can be several times the battery current. If the body diodes in the FETs are used as freewheels, there is a much higher heat dissipation since they drop more voltage than a FET that's turned on. This is a frequent cause of failure.
"One test is worth a thousand opinions"
User avatar
fechter
100 GW
100 GW
 
Posts: 10751
Joined: Sun Dec 31, 2006 3:23 pm
Location: California Bay Area, USA

Re: Motorboard project

Postby Stielz » Fri Jul 01, 2011 7:25 pm

I am finally finished with exams and assignments and had some decent time to spend on getting my motor controller working.
here are some pictures of the setup, I know its messy but thers not much I can do about that.

CIMG0098.JPG
Motor
CIMG0098.JPG (237.57 KiB) Viewed 6997 times


CIMG0099.JPG
Controller
CIMG0099.JPG (230.65 KiB) Viewed 7014 times


I an only running it on 12.6V at the moment with a 3s lipo I have laying around, hence the low speed of 600 RPM at 66% duty cycle.
At 100% duty cycle it will get up to 1400 RPM and draw around 3 amps RMS. The switching frequency is 21.6 kHz. I have tried it with lower frequencies and it gets quite loud so I will stick 21.6 kHz for now.

I have tested it out with a 30V power supply, however the power supply could only do 5 Amps. Even at low duty cycles the peak current would exceed that so it was bouncing on and off the current limiter which made it run pretty poorly.

My 5s batteries and current sensor should be arriving within the next few weeks so I will be able to test it out properly soon.

The next mission is to program the reverse and braking functions
User avatar
Stielz
100 W
100 W
 
Posts: 239
Joined: Fri May 20, 2011 11:54 pm
Location: Wellington, New Zealand

Next

Return to Stand-up E-scooters and E-skateboards

Who is online

Users browsing this forum: No registered users and 7 guests