The Greenstage Team has been helping Switch EV with final tuning and testing on their Electric Holden Ute. We decided to capture some of the action and we have put together a little montage, with a hint to what's coming next as well.
If you're after more information, check out earlier Switch EV blog posts part 1 and part 2.
Enjoy!
Showing posts with label inverter. Show all posts
Showing posts with label inverter. Show all posts
Sunday, September 9, 2012
Friday, July 6, 2012
KiwiAC driving Switch EV Induction motor … Part 2: Motor Control
Following on from our bench testing earlier in June, Switch EV have installed their motor into their test vehicle and undergone some driveway testing. Sorry no video or photos this time, just output logs turned into pretty graphs (go LibreOffice!)
At the most basic level we are controlling motor current. Our serial output is not fast enough to report every current measurement (two performed every 12kHz), but we can see if the current is behaving within the region we expect. First we can compare the requested current output magnitude, vs raw, directly sampled phase currents. The vertical axis is a signed internal scale, where 32700 is approximately 1000 Amps.
Delving into the Motor Model at the heart of Field Oriented Control, we can check that the two current vectors, (magnetic flux producing Id and torque producing Iq) are controlling:
Here, the error between requested Id and Iq are plotted as DId and Diq. The error is around 1%, which equates to a output Torque error of about 0.01% (output Torque is proportional to motor flux times torque current).
At the moment, we are controlling Flux and Torque to equal throttle position (thick grey line). Flux (the green line) should always be positive however, (as two negative numbers would multiply to a positive torque). We have set the throttle zero position to produce regen torque, to approximate engine braking, but only while moving. You can see at 175 seconds when the vehicle was stopped that the torque and flux trending to zero, no longer following the throttle position. A small acceleration occurs from 184-193 seconds, and a much greater one at 205 seconds.
This final graph shows power in the controllers DC bus, versus the calculated mechanical motor power (estimated torque times motor speed) and an estimation of the inverter and motor AC conduction losses. At the time the car was traversing undulating terrain, so change in speed does not correspond that well to delivered power.
Finally, a big thanks to Lachlan for putting together the data extraction scripts that made these graphs possible and to Switch EV for building such a great EV!
Stay tuned, driving videos coming soon...
At the most basic level we are controlling motor current. Our serial output is not fast enough to report every current measurement (two performed every 12kHz), but we can see if the current is behaving within the region we expect. First we can compare the requested current output magnitude, vs raw, directly sampled phase currents. The vertical axis is a signed internal scale, where 32700 is approximately 1000 Amps.
Here you can see that every reported current is within the magnitude
requested. Because of stroboscopic effects, (sampling windows and AC
sinusoidal waveforms etc) it is expected that we would see values less
than requested current.
Delving into the Motor Model at the heart of Field Oriented Control, we can check that the two current vectors, (magnetic flux producing Id and torque producing Iq) are controlling:
Here, the error between requested Id and Iq are plotted as DId and Diq. The error is around 1%, which equates to a output Torque error of about 0.01% (output Torque is proportional to motor flux times torque current).
At the moment, we are controlling Flux and Torque to equal throttle position (thick grey line). Flux (the green line) should always be positive however, (as two negative numbers would multiply to a positive torque). We have set the throttle zero position to produce regen torque, to approximate engine braking, but only while moving. You can see at 175 seconds when the vehicle was stopped that the torque and flux trending to zero, no longer following the throttle position. A small acceleration occurs from 184-193 seconds, and a much greater one at 205 seconds.
Finally, a big thanks to Lachlan for putting together the data extraction scripts that made these graphs possible and to Switch EV for building such a great EV!
Stay tuned, driving videos coming soon...
Wednesday, April 11, 2012
Dyno Progress
For a while now we had the plan to build a dynamometer out of two Siemens made Ford Ranger AC motors.
While no calibrated results could be made (through measuring the
torque directly) the contraption would be very useful for comparative
analysis of motor control regimes and settings.The first steps (October last year) involved working out how to couple the two together. The motor shaft is hollow to allow a further shaft to run directly through the motor. The output end of the shaft has a helical gear directly machined into it, for a now unavailable planetary gear set. Others have suggested directly welding to the shaft, some have success using taper-lock devices directly on the gear.
In our situation, because of its
non-critical nature (a failure is not likely to put
anyone in a compromised situation), we decided to go with another
untested route – developing a bush that works somewhat like an
inside out double ended collet holder. Made of brass it may not be as
strong as the rest of the equipment, but simple to make on the lathe,
and not likely to damage the motors for future applications.
As previously mentioned Stephen
designed and organised an adaptor plate for bolting the motors
together. The motors are now coupled, and spinning just about as
freely as individually so must be fairly close to aligned.
Due to the weight of the combined
motors (over 130kg) we wanted to be able to wheel them around. We started to think about building a trolley but instead opted for far cheaper and easier option - a 200kg rated handcart.
Next came the job of hooking up the motor encoder and temperature sensors. Reportedly there isn't a plug available
for the encoder connector on the motor, so a new arrangement is
required.
I don't think that the plastic connectors that the motors are delivered with were originally part of the plan. The tapped hole for the closest cover bolt breaks through into the hole for the connector. Worse still, an o-ring seal sits beyond where the bolt hole breaks through, which means the o-ring is damaged every time the fitting is removed or put back in. Not a clever design, but we will run with it for the mean time.
Next came the job of hooking up the motor encoder and temperature sensors. Reportedly there isn't a plug available
for the encoder connector on the motor, so a new arrangement is
required.
We made a stainless piece that reduces
the hole to suit the M23 servo-motor style encoder connector used on standard Siemens motors.
I don't think that the plastic connectors that the motors are delivered with were originally part of the plan. The tapped hole for the closest cover bolt breaks through into the hole for the connector. Worse still, an o-ring seal sits beyond where the bolt hole breaks through, which means the o-ring is damaged every time the fitting is removed or put back in. Not a clever design, but we will run with it for the mean time. Friday, March 16, 2012
A little bit of fabrication
Over the last couple of months there have been a few changes to accommodate the new race battery pack in the GS750V and to brace the motor appropriately as we head towards full torque output. Below you can see the new brackets that prevent the motor's aluminium body from carrying all the torque and they also provide a new mounting point for the the inverter just above the motor.
In addition to that, we have put together our dual motor dyno ready for fine tuning of the motor control algorithms under development in the Tumanako project.
Big thanks to Stephen for driving the details and making this happen and also to the Spaceships crew and PureAdvantage for the support along the way. Thanks also to the fine Engineering work and support provided by Abel Metal Products, Primero Profiles, Tordeich Engineering and Ladarac.
We are now ready for the batteries!
 |
| Multi purpose bracing brackets |
In addition to that, we have put together our dual motor dyno ready for fine tuning of the motor control algorithms under development in the Tumanako project.
 |
| Dyno for motor tuning |
Big thanks to Stephen for driving the details and making this happen and also to the Spaceships crew and PureAdvantage for the support along the way. Thanks also to the fine Engineering work and support provided by Abel Metal Products, Primero Profiles, Tordeich Engineering and Ladarac.
We are now ready for the batteries!
Sunday, February 27, 2011
Black Magic Debug Probe
Thanks to Gareth McMullin, I recently had the pleasure of using Black Sphere Technologies Black Magic Probe. This wonderful little device is used for debugging embedded applications running on an ARM STM32.
Here's a little demo running on a STM32MCU where I set a break point in the shutdownPower method of the Tumanako Vehicle Control application and then use backtrace to see the flow of application code to that point:
In addition to being better than anything else available, this great tool is also fully Open Source! All information is freely available here:
Thank you Gareth!
Here's a little demo running on a STM32MCU where I set a break point in the shutdownPower method of the Tumanako Vehicle Control application and then use backtrace to see the flow of application code to that point:
pccourt@Greenstage:~/tumanako/trunk/inverter/fw/vehicle_control/src$ arm-none-eabi-gdb tumanako_vc_sineHow cool is that! No fluffing about, it just works and its as fast as debugging a program running on your host CPU. As a result, this tool has now become an essential component of Greenstage's hardware and software development lab.
GNU gdb 6.8
Copyright (C) 2008 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law. Type "show copying"
and "show warranty" for details.
This GDB was configured as "--host=i686-pc-linux-gnu --target=arm-none-eabi"...
Device IR Len IDCODE Description
0 4 0x3BA00477 ARM Limited: ADIv5 JTAG-DP port.
1 5 0x16410041 ST Microelectronics: STM32, Medium density.
Available Targets:
No. Att Driver
1 STM32, Medium density.
0x1ffff3ba in ?? ()
(gdb) load tumanako_vc_sine
Loading section .text, size 0x113c4 lma 0x8000000
Loading section .data, size 0x624 lma 0x80113c4
Start address 0x8000000, load size 72168
Transfer rate: 10 KB/sec, 962 bytes/write.
(gdb) break STM32_sine_interface.cpp:533
Breakpoint 1 at 0x8001ad4: file STM32_sine_interface.cpp, line 533.
(gdb) run
The program being debugged has been started already.
Start it from the beginning? (y or n) y
Starting program: /home/pccourt/tumanako/trunk/inverter/fw/vehicle_control/src/tumanako_vc_sine
Note: automatically using hardware breakpoints for read-only addresses.
Breakpoint 1, STM32Interface::shutdownPower (this=0x20004fe8) at STM32_sine_interface.cpp:533
533 TIM1_BDTR &= (uint16_t)~(TIM_BDTR_MOE); //main output enable OFF
(gdb) bt
#0 STM32Interface::shutdownPower (this=0x20004fe8) at STM32_sine_interface.cpp:533
#1 0x08000ec0 in TumanakoInverter::stateMachineDo (this=0x20004fd0) at tumanako_inverter.cpp:653
#2 0x08001472 in TumanakoInverter::doIt (this=0x20004fd0) at tumanako_inverter.cpp:459
#3 0x080001ee in main () at main.cpp:157
(gdb)
In addition to being better than anything else available, this great tool is also fully Open Source! All information is freely available here:
- Website: http://www.blacksphere.co.nz/
main/blackmagic - Project: http://sourceforge.net/
projects/blackmagicdebug - Wiki: http://sourceforge.net/apps/
mediawiki/blackmagicdebug
Thank you Gareth!
Saturday, October 24, 2009
Saker GS750V motor and wheel rotation!
Today Ed, Mark and myself (with visits from Tom, Tabitha and Frank) achieved what we have been waiting nearly 12 months for. We had the GS750V powered up and turning it's own wheels!
Well done guys!!! This is an awesome achievement. Thanks to all that have helped us in getting to this point, both locally and internationally.
Read on for more details...
Our plan had the day broken into 4 phases:
1) Re-test the 30V test rig setup after it had been relocated from the software dev environment.
2) Test the 1.1kW motor from the test rig with the 150V test pack.
3) Lunch and forgotten encoder cable provided by Kirstin :)
4) Upgrade the 1.1kW motor to the Siemens motor in the GS750V and watch the wheels turn!
The setup we had is still very much a work in progress since the STM32 and Tumanako control board is not yet installed in the inverter casing. Hence the inverter and the control board where setup on a table beside the car for this test. The contactors where situated in a temporary but secure location which was convenient to get the power from the battery to the inverter.
You can see the setup we had for phase 2 in the photo below:
After a successful morning and a smiling visit from Kirstin, we moved into the business end of the day. We jacked the car onto blocks and connected up the Siemens 1PV5135 WS28 motor, which is already mounted in the car and connected to the gearbox. After an initial juddery rotation and a blown fuse (test pack fuse is only 30A so we don't stress the batteries), Ed discovered the encoder was hooked up incorrectly. So, rather than simply replacing the fuse, Mark upgraded it to a breaker which is resetable if something goes wrong and also easily used to make the pack safe during maintenance. Thank you Mark!
After addressing the encoder wiring and increasing the flux limits on our torque control, we got some very smooth motor control indeed. Check it out (please excuse the battle Ed is having with the forward/reverse torque control POT we had setup for the test in this video):
So, it's the home straight now! We need to complete the single Tumanako control board, finish off the wiring loom and complete the associated vehicle control software (adding additional safety checks and vehicle loom IO). Then we will be ready for dyno tuning (motor parameters need work) and of course squeezing in the first test drive :)
Also, expect to see a high quality video of todays test uploaded in the next couple of days. I'm currently looking for a cable from my sons video camera that I borrowed!? I hope I don't get into trouble :)
-Philip
Well done guys!!! This is an awesome achievement. Thanks to all that have helped us in getting to this point, both locally and internationally.
Read on for more details...
Our plan had the day broken into 4 phases:
1) Re-test the 30V test rig setup after it had been relocated from the software dev environment.
2) Test the 1.1kW motor from the test rig with the 150V test pack.
3) Lunch and forgotten encoder cable provided by Kirstin :)
4) Upgrade the 1.1kW motor to the Siemens motor in the GS750V and watch the wheels turn!
The setup we had is still very much a work in progress since the STM32 and Tumanako control board is not yet installed in the inverter casing. Hence the inverter and the control board where setup on a table beside the car for this test. The contactors where situated in a temporary but secure location which was convenient to get the power from the battery to the inverter.
You can see the setup we had for phase 2 in the photo below:
After a successful morning and a smiling visit from Kirstin, we moved into the business end of the day. We jacked the car onto blocks and connected up the Siemens 1PV5135 WS28 motor, which is already mounted in the car and connected to the gearbox. After an initial juddery rotation and a blown fuse (test pack fuse is only 30A so we don't stress the batteries), Ed discovered the encoder was hooked up incorrectly. So, rather than simply replacing the fuse, Mark upgraded it to a breaker which is resetable if something goes wrong and also easily used to make the pack safe during maintenance. Thank you Mark!After addressing the encoder wiring and increasing the flux limits on our torque control, we got some very smooth motor control indeed. Check it out (please excuse the battle Ed is having with the forward/reverse torque control POT we had setup for the test in this video):
So, it's the home straight now! We need to complete the single Tumanako control board, finish off the wiring loom and complete the associated vehicle control software (adding additional safety checks and vehicle loom IO). Then we will be ready for dyno tuning (motor parameters need work) and of course squeezing in the first test drive :)
Also, expect to see a high quality video of todays test uploaded in the next couple of days. I'm currently looking for a cable from my sons video camera that I borrowed!? I hope I don't get into trouble :)
-Philip
Friday, October 2, 2009
Turning wheels...
You may be asking, what's happening with the GS750V (the Electric Saker)? As you may know, almost 12 months ago exactly we discovered that the inverter we purchased was a little deficient (due to software issues that have not been addressed by the manufacturer).
Thankfully, this is one of the areas the Open Source Tumanako projects have been making great progress in. If you have not been following the Tumanako projects, I suggest you take a quick peek at the Tumanako blog.
Although there is still significant work to be done before a full Open Source inverter and vehicle control software system is released, I can confirm we will see the wheels turning on the GS750V in the near future.
Stay tuned for the video!
Thankfully, this is one of the areas the Open Source Tumanako projects have been making great progress in. If you have not been following the Tumanako projects, I suggest you take a quick peek at the Tumanako blog.
Although there is still significant work to be done before a full Open Source inverter and vehicle control software system is released, I can confirm we will see the wheels turning on the GS750V in the near future.
Stay tuned for the video!
Sunday, March 22, 2009
Tumanako
A long term stated goal of Greenstage has been to promote and develop open source technology. I thought this would play out significantly in the future, once we had the GS750V completed and racing. The immediate issues with our inverter are preventing the completion of the GS750V, interestingly they have also created an opportunity to bring our long term plans forward and hence solve our current problems. All in one go!
On the Wednesday just gone we hosted an international launch party for a number of open source EV projects. The event was a gathering of very capable people showing much enthusiasm for the projects and EV technology in general. These projects are collectively being developed under the Tumanako banner (Tu manako is Māori for hope & togetherness) and so far aspects of Tumanako have received commitment for technical and financial support from 5 different entities (and I expect more to follow):
EV Drive - Bob Simpson
Metric Mind Corporation - Victor Tichonov
Disruptive Enterprises - Alex Smith
Lynx Innovation - Kevin Huljich
Greenstage - Team Greenstage
As well as the open source technical design and development I am very aware of the importance of fostering and developing commercial manufacturing, testing, packaging and sales aspects of the resulting products. Without this the projects will become just another wad of information that only a small subset of people can make use of. The commercial entities supporting and bringing these open source products to market will provide consumers and OEM's with the opportunity to leverage these products with confidence. Combined with the long term technical benefits of open source development, this synergistic commercial manufacturing has the very real opportunity to create a strong and attractively priced set of products.
To learn more about the Tumanako projects, visit our Tumanako Launch wiki page where you can see some of the presentations and photos from the evening. The Tumanako projects are being hosted on SourceForge and changes will be visible as development progresses.
We already have a formidable team and this team will only grow and get stronger as the projects progress. If you have an interest in the outcome of these projects, or you would like to get involved, please let us know.
Let the fun begin!
Tuesday, January 27, 2009
2009 - Optimism in the face of adversity
You can probably guess from the lack of celebratory post, that we have not had the car driving yet. We are still working with the inverter manufacturer to get this resolved. The crux of the issue is the DSP board and the software that runs on it. I hope to have more information and positive news about this situation next week.
In the mean time we are still looking at the bigger picture of what this GS750V project is about. Pre Xmas I became aware of the SolarNetwork project being lead by John Gorman. This Open Source project aims to create a network of solar nodes, where each node measures locally generated power (from PV cells or similar) and local power consumed. All this information is collected together and used to predict future generation and consumption scenarios based on weather forecasts and the future build out of solar node infrastructure.
I believe this solar node network and its associated data will become a very powerful tool to plan future business models and business expansion with respect renewable energy generation.
The other exciting opportunity John and I have discussed, is the opportunity to expand the SolarNetwork infrastructure to support V2G (vehicle to grid) functionality. The idea being that if the owner of the EV plugs the car in for a top up, indicates that they want to minimise the cost of the charge (and the impact on the environment) and that they will not need the car for another 4 hours say. This then allows the V2G system to effectively sell power from the EV battery pack during peak demand and charge the pack when demand is less and power is cheaper. The V2G system manges this process to ensure the pack is fully charged upon the owners return. Of course the owner also has the option to tell the V2G system to just charge the pack as quickly as possible and keep it that way until they return if thats what they desire.
This may sound like a magical fairy tale, but from a software engineering point of view this fits into the category of a very doable medium scale project. The bigger challenge is with the physical infrastructure. This is where the beauty of attacking it with an Open Source project comes in. It will allow the basic concept to be developed to a working stage with one specific type of infrastructure (e.g a specific charger and/or inverter combination). The capability can then be expanded by adding additional functionality to the control algorithms and by adding support for other brands and models of infrastructure (i.e. other manufactures charges and inverters).
Greenstage has already ordered a solar node and hopes to be on the SolarNetwork in the next couple of months. If you would like a solar node, or to get involved with the development, please contact John and let him know how great his project is.
Why wait for the world to change? Lets just do what needs to be done!
In the mean time we are still looking at the bigger picture of what this GS750V project is about. Pre Xmas I became aware of the SolarNetwork project being lead by John Gorman. This Open Source project aims to create a network of solar nodes, where each node measures locally generated power (from PV cells or similar) and local power consumed. All this information is collected together and used to predict future generation and consumption scenarios based on weather forecasts and the future build out of solar node infrastructure.
I believe this solar node network and its associated data will become a very powerful tool to plan future business models and business expansion with respect renewable energy generation.
The other exciting opportunity John and I have discussed, is the opportunity to expand the SolarNetwork infrastructure to support V2G (vehicle to grid) functionality. The idea being that if the owner of the EV plugs the car in for a top up, indicates that they want to minimise the cost of the charge (and the impact on the environment) and that they will not need the car for another 4 hours say. This then allows the V2G system to effectively sell power from the EV battery pack during peak demand and charge the pack when demand is less and power is cheaper. The V2G system manges this process to ensure the pack is fully charged upon the owners return. Of course the owner also has the option to tell the V2G system to just charge the pack as quickly as possible and keep it that way until they return if thats what they desire.
This may sound like a magical fairy tale, but from a software engineering point of view this fits into the category of a very doable medium scale project. The bigger challenge is with the physical infrastructure. This is where the beauty of attacking it with an Open Source project comes in. It will allow the basic concept to be developed to a working stage with one specific type of infrastructure (e.g a specific charger and/or inverter combination). The capability can then be expanded by adding additional functionality to the control algorithms and by adding support for other brands and models of infrastructure (i.e. other manufactures charges and inverters).
Greenstage has already ordered a solar node and hopes to be on the SolarNetwork in the next couple of months. If you would like a solar node, or to get involved with the development, please contact John and let him know how great his project is.
Why wait for the world to change? Lets just do what needs to be done!
Saturday, December 13, 2008
Half shafts and software installed
Today our goal was to install the half shafts and have a go at loading the inverter software.
On the mechanical side of things, Frank and Ed installed the half shafts without too many issues. We had to muck around splitting the gearbox end of the shafts open to get them past the chassis but nothing that needed any grinding. The pins are in, filled with grease, but not siliconed and taped yet. Also, we need to torque the bolts (must not forget this!).
After a bit of mucking around Tom and Ed managed to load the inverter software, we did manage to engage the contactors, but no motor rotation as yet. It may be that the configuration needs to be updated for the WS28 version of the Siemens motor? We need to get some direction from the supplier because as far as we can see everything is correctly configured and wired up. Hopefully its something simple.
To finish the day off, we took the GS750V to the Pukekohe race track to get a few 2008 pictures of the car and the Greenstage Racing Team. This had been on the todo list for a while and we needed to get it sorted before everyone departed for Xmas. We got some nice shots while chatting with a few of the remaining motorcycle crowd (they had been at the track all day and were packing up as we arrived). It's great fun when people show an interest, especially when they find out it's electric and give us the big thumbs up!
So, another step forward and a few more still to go. Heaps of thanks to Frank, Ed, Tom, Thomas, Emma and Hugh. You guys rock!
On the mechanical side of things, Frank and Ed installed the half shafts without too many issues. We had to muck around splitting the gearbox end of the shafts open to get them past the chassis but nothing that needed any grinding. The pins are in, filled with grease, but not siliconed and taped yet. Also, we need to torque the bolts (must not forget this!).
After a bit of mucking around Tom and Ed managed to load the inverter software, we did manage to engage the contactors, but no motor rotation as yet. It may be that the configuration needs to be updated for the WS28 version of the Siemens motor? We need to get some direction from the supplier because as far as we can see everything is correctly configured and wired up. Hopefully its something simple.
To finish the day off, we took the GS750V to the Pukekohe race track to get a few 2008 pictures of the car and the Greenstage Racing Team. This had been on the todo list for a while and we needed to get it sorted before everyone departed for Xmas. We got some nice shots while chatting with a few of the remaining motorcycle crowd (they had been at the track all day and were packing up as we arrived). It's great fun when people show an interest, especially when they find out it's electric and give us the big thumbs up!
So, another step forward and a few more still to go. Heaps of thanks to Frank, Ed, Tom, Thomas, Emma and Hugh. You guys rock!
Monday, December 8, 2008
Busy weekend
It's been a busy weekend. Frank took out the Electric go carting on Saturday, the first cut of the inverter software arrived later the same day and on Sunday, Ed and I were at the Clevedon Farmers Market showing off the GS750 with assistance from Dylan and Robert.
As usual the car generated a lot of interest and we have extended our network of contacts a little further. Thanks to everyone for the great weekend.
So now that we have the software, it's time to get this car rolling!
As usual the car generated a lot of interest and we have extended our network of contacts a little further. Thanks to everyone for the great weekend.
So now that we have the software, it's time to get this car rolling!
Tuesday, October 28, 2008
A few missing things
Back to normal!? After the speed show we have had a bit of a hiatus while we got back to more mundane things like sorting out paper work and catching up on sleep.The passing of time also helps to address things you are waiting on. At the speed show, we were still waiting on the completion of a few key components. The good news is that our half shafts have been completed and Bruce has sent them up from Bunnythorpe.
The bad news is that we are still waiting on the completion of the inverter software required to drive the car. It appears that the software engineering has been more time consuming than expected (who forgot to double the estimate?), but it shouldn't be too far away now. The first cut is expected in late November.
In the meantime we have been working on our proposal for potential major sponsors. As a direct result of the Speed Show, we have already been approached by one likely candidate (they were on our list of potential sponsors). We believe the marketing opportunities are immense and we hope to expand the imagination and reality of both the public and corporate partners with what we have to offer.
Stay tuned as we knock off the remaining tasks in preparation for the track.
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