Burties 'special apparatus' (RC dyno) lives
- Thread starter Burtie
- Start date
It is turning out to be quite of work to get this all functioning well, but it is all coming on slowly.
There are now two solutions for the electrical load on the generator:
1) I have added a 2nd controller to allow regeneration from the generator back into the power source. This seems to work ok, and we can recover about half the electrical energy we put into driving the motor.
So, for a 1kw input from the PSUs, I can drive the motor with 2kw.
The disadvantage is that the regen from this Xiechang controller is not variable except by reflashing the parameters, which is a hassle.
I am also concerned that this method may possibly introduce some unpredictable torque ripple, making the whole dyno run roughly.
2) I have built an array of 12v 50w halogen bulbs, which can be configured in several ways ( Delta or Wye, and 12v or 24v), to provide different loads for a given speed.
The whole array is capable of dissipating a maximum of about 2kw of electrical energy, and does a good job of heating my room during this cold weather
http://www.youtube.com/watch?v=xhPR8mAKgVk
[youtube]xhPR8mAKgVk[/youtube]
Burtie
There are now two solutions for the electrical load on the generator:
1) I have added a 2nd controller to allow regeneration from the generator back into the power source. This seems to work ok, and we can recover about half the electrical energy we put into driving the motor.
So, for a 1kw input from the PSUs, I can drive the motor with 2kw.
The disadvantage is that the regen from this Xiechang controller is not variable except by reflashing the parameters, which is a hassle.
I am also concerned that this method may possibly introduce some unpredictable torque ripple, making the whole dyno run roughly.
2) I have built an array of 12v 50w halogen bulbs, which can be configured in several ways ( Delta or Wye, and 12v or 24v), to provide different loads for a given speed.
The whole array is capable of dissipating a maximum of about 2kw of electrical energy, and does a good job of heating my room during this cold weather
http://www.youtube.com/watch?v=xhPR8mAKgVk
[youtube]xhPR8mAKgVk[/youtube]
Burtie
adrian_sm
1 MW
This looks fantastic. I want one.
You mentioned you were decoding the display info to get data out of the watt meter. Jonas (Umejopa) reverse engineered the turnigy watt meter code. He modified it to act as a throttle interface between a hall throttle and a RC ESC, including amp limitting etc. So you might be able to tweak the code to your needs if you want. Note: I think the newer Watt Meter models have changed uP, so may only work on old models.
Here is a link to the first post he made publishing the code: http://www.endless-sphere.com/forums/memberlist.php?mode=viewprofile&u=16563
I have also noticed that the Amp readings are reported inaccurately at low amps, reporting too low a reading. So if this is your main power measurement, you may want to check calibration.
Keep up the outstanding work.
- Adrian
You mentioned you were decoding the display info to get data out of the watt meter. Jonas (Umejopa) reverse engineered the turnigy watt meter code. He modified it to act as a throttle interface between a hall throttle and a RC ESC, including amp limitting etc. So you might be able to tweak the code to your needs if you want. Note: I think the newer Watt Meter models have changed uP, so may only work on old models.
Here is a link to the first post he made publishing the code: http://www.endless-sphere.com/forums/memberlist.php?mode=viewprofile&u=16563
I have also noticed that the Amp readings are reported inaccurately at low amps, reporting too low a reading. So if this is your main power measurement, you may want to check calibration.
Keep up the outstanding work.
- Adrian
liveforphysics
100 TW
I love your amazing work Burtie!!! This is awesome!
More data!
More data!
acuteaero
100 W
Very cool. This is the killer tool for developing and testing motor control hardware!
Looks like the load cell you're using is one of the cheap ones from eBay seller scale_bargains . Is it? That's what I was thinking about using on my project over here http://endless-sphere.com/forums/viewtopic.php?f=30&t=36803
I'm guessing you're not using their A/D USB board- are you using one of their little amplifier/exciter boards? Or how otherwise are you managing the excitiation/signal conditioning?
Thanks! And again- awesome project!
Looks like the load cell you're using is one of the cheap ones from eBay seller scale_bargains . Is it? That's what I was thinking about using on my project over here http://endless-sphere.com/forums/viewtopic.php?f=30&t=36803
I'm guessing you're not using their A/D USB board- are you using one of their little amplifier/exciter boards? Or how otherwise are you managing the excitiation/signal conditioning?
Thanks! And again- awesome project!
Doctorbass
100 GW
Awsome!..
and for those who would like a great ebike front lamp.. think about it :lol:
and for those who would like a great ebike front lamp.. think about it :lol:
johnrobholmes
10 MW
Very cool, love the torque arm setup!
Thanks guys, glad you like it.
Adrian, thanks for the tips on the Turnigy watt meter. I will be sure to check the calibration of the sensors before I take any of the readings too seriously.
Acuteaero, Yes the load cell stuff comes from the cheap source on ebay (search for 'load cell kit' ). It uses parts from the 25lb kit.
The microprocessor, and usb link of the kit are not useable for this job, because the firmware wont output any readings unless the load on the cell is absolutely constant (which it never will be on an operating dyno).
The front end of the kit uses an Avia HX711 chip which is a combined instumentation amp and autonomous 24 bit ADC. You can find a summary data sheet for it on the internet:
http://www.aviaic.com/UpLoadFile/hx711_brief_en.pdf
If you look at the kit pcb, you can find two tracks carrying clock and serial data going from this chip (pin 11 +12) to the processor.
You will need to connect your own microprocessor to these clock and data lines to capture the 24bit data which is transmitted 11 times a second.
You will then need to write your own filtering and scaling/calibration functions.
Burtie
PS I like your approach of using a car alternator as the generator and varying the field current to change the load, -very neat :wink:
Adrian, thanks for the tips on the Turnigy watt meter. I will be sure to check the calibration of the sensors before I take any of the readings too seriously.
Acuteaero, Yes the load cell stuff comes from the cheap source on ebay (search for 'load cell kit' ). It uses parts from the 25lb kit.
The microprocessor, and usb link of the kit are not useable for this job, because the firmware wont output any readings unless the load on the cell is absolutely constant (which it never will be on an operating dyno).
The front end of the kit uses an Avia HX711 chip which is a combined instumentation amp and autonomous 24 bit ADC. You can find a summary data sheet for it on the internet:
http://www.aviaic.com/UpLoadFile/hx711_brief_en.pdf
If you look at the kit pcb, you can find two tracks carrying clock and serial data going from this chip (pin 11 +12) to the processor.
You will need to connect your own microprocessor to these clock and data lines to capture the 24bit data which is transmitted 11 times a second.
You will then need to write your own filtering and scaling/calibration functions.
Burtie
PS I like your approach of using a car alternator as the generator and varying the field current to change the load, -very neat :wink:
E-racer
1 kW
This thing rocks! i just noticed it. Any clue what the peak power rpm is for a 6 turn delta 80-100?
E-racer
1 kW
Burtie said:
I've found that is not the case when running a NV cvt. If i set the transmission to hold 5000 rpm my bike is slower than if i set it to 4000. My butt dyno says that 4000rpm +/-500rpm seems to feel about the same. I'd love to really know where all the power is.
Yes, I guess when considering the whole system, taking into account the system battery voltage, and the controller limits and controller limiting mechanisms, there will be an optimum rpm for maximum power output.
For this question, I think it is needed to consider the whole system rather than the motor in isolation.
For this question, I think it is needed to consider the whole system rather than the motor in isolation.
Green Machine
100 kW
So i was at the astro flight motor factory the other day and i noticed they had built a similar dyno to test their motors. It was the coolest machine i saw in the whole factory.
However they were using a water brake on theirs, and a torque sensing unit. I think Burtie's design is probably better and much cheaper to build.
I really want to build one of these dynos so that i can test different motor set ups for climbing up pikes...also for testing efficiency of different motors, and getting real data on how reliable and efficient each motor is..even hub motors.
However they were using a water brake on theirs, and a torque sensing unit. I think Burtie's design is probably better and much cheaper to build.
I really want to build one of these dynos so that i can test different motor set ups for climbing up pikes...also for testing efficiency of different motors, and getting real data on how reliable and efficient each motor is..even hub motors.
acuteaero
100 W
Green Machine said:
Hey Eric- don't know if you saw the thread I started a while back- http://endless-sphere.com/forums/viewtopic.php?f=30&t=36803 I wrote a bit about the different types of dynos (waterbrake, etc) there. I am going to finish my dyno up in the next few weeks-ish... in order to do some RC motor testing primarily to get PaulD's bike running reliably. I'm right in your neighborhood- if you're interested you'd certainly be invited to check it out when I get it going. I have some 80100 motors, some 6364 motors and an Astro 3210 to run tests with... Burtie also supplied some details about his software/hardware setup in that thread. Speaking of which...
Sorry for the little thread-jacking there...
Green Machine said:
Yes, the Electrcal power in, RPM and Torque data from the various sensors, is all read by a PIC18 u-processor, running custom firmware.
The data from the sensors is filtered and sent out on a serial link.
There is a custom c# application running on the PC that reads the serial data and displays it. This application also calculates efficiency figures and averages, and provides the user with the facilities to calibrate/scale the sensors.
Unfortunately some of the hardware is cobbled together with odd bits from my electronics junk box, so it would not be easy to replicate exactly.
(This is the particular processor board I used: http://www.futurlec.com/ET-PIC_Stamp.shtml )
Burtie
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