Today’s development on IONI Pro has revolved around the development of feature called Peak power limit. With that, user can set the exact amount of Watts that drive is allowed to transfer from PSU to motor.
This may be useful when using drive from a switch mode power supplies that normally shut down on overload condition. With this parameter, one can set exact amount of power that is available from PSU to prevent overloads. This also helps to save money on power supply as there is less need oversize the PSU in order to handle the highest load peaks.
To celebrate the new year 2016, we have released a new IONI firmware version 1.4.0. It includes rewritten torque controller that uses 32 bit floating point precision arithmetics instead of integer arithmetics. As IONI has hardware FPU, it yielded faster code execution time as well. This makes more room for the new upcoming features.
IONI Pro HC model maximum output current in AC/BLDC/Stepper modes increased to 25A (was 23A)
Re-implemented torque controller using 32 bit floating point arithmetics instead of integer arithmetics (at least theoretical precision improvement)
DC motor mode no longer requires parallel connection of drive output phases if current is at most 50% of drive’s maximum output current capability (sensitivity of overcurrent fault with Fault ID 440219 is greatly reduced).
Changed limit switch polarity: earlier limit switches needed to be normally open (NO), while drive specifications say that they are normally closed type (NC). Now limit switchers are NC (switch conducting -> motion allowed, switch open -> motion stops).
Fix an issue where AC/BLDC motor initialization could become incorrectly phased when Hall sensors are enabled
Address an issue where torque was 5% lower than setpoint with TBW parameter value of 4700 Hz
The decision to build a racing simulator with servo motor based force feedback has yielded first tangible results. The picture below shows the current setup of a force feedback wheel with a 36 Nm (peak) motor equipped with a sin/cos encoder. The system is being driven by IONI Pro HC and a STM32 Discovery based interface.
Simulator direct drive FFB wheel is operational but currently it lacks other controls. Mechanical parts design and tooling was implemented by Aki.
The first test drive on iRacing put a wide smile on our faces immediately and gave more motivation to make faster progress on it :)
The plan is to experiment with wheel effect calculations, such as friction, inertia, damping and spring, inside the drive firmware to take full advantage of high resolution feedback devices. Also it’s a good platform to test how far IONI can be pushed in output current ratings in this kind of system.
We run number of tests to each manufactured drive, one of them being a load endurance test. The test is done by driving constant 9 Amp sinusoidal current from all four power lanes and clocking the time of how long it takes drive to heat up by 25 Celsius. This test is used to verify proper characteristics of the power stage. Each tested drive must score above a certain level of endurance to be passed.
Load endurance test with IONI Pro and IONI Pro HC
The statistics above shows endurance results from about 200 tested drives. From here we can see that Pro HC model has average endurance times of 47.7 seconds while Pro has average of 27.5 seconds. This means that on average HC model takes 1.73 times longer to get equally warm during the test. On the other hand, it could be understood that on average HC model dissipates 42% less heat.
The test also reveals that the variance is higher on HC model. There are few extraordinary good units probably due to varying characteristics of the MOSFETs even though both model MOSFETs are made by same manufacturer. Pro HC model uses the newest and lowest loss type that is available today in this size while Pro uses couple of steps lower rated devices. I hope some day the MOSFET manufacturer manages to avoid the variance and start offering transistors that perform like the best ones seen here.
Despite of the variance, the best thing is that there is clear bottom level on both types, so any unit will not have troubles meeting the specs.
We have released new firmware files for Argon and Ioni today. Also Granity has been updated.
Argon V2.0.0 beta 4
All reported bugs have been addressed. Beta 4 is a release candidate and it will become official 2.0 if no further problems are found. Once tested, please send feedback about it (email or comment here, also please tell which control mode you are using: torque, velocity or position). Or give vote on the poll on the right sidebar. Get the firmware from here.
This update includes lots of changes since the last release. For full change log and downloads, see this wiki page. Feedback is very welcome.
The latest Granity includes support for the Ioni V1.3.0 as well as some improvements. Starting from this release, it includes also Linux version!
Development today focused on improving torque smoothness of motors. Some motors, especially cheaper ones and stepping motors, suffer from cogging torque:
“Cogging torque of electrical motors is the torque due to the interaction between the permanent magnets of the rotor and the stator slots of a Permanent Magnet (PM) machine. It is also known as detent or ‘no-current’ torque. This torque is position dependent and its periodicity per revolution depends on the number of magnetic poles and the number of teeth on the stator.”
This can be compensated by modulating motor current to counter the motor cogging. The firmware under development adds options to adjust compensation current by few new parameters.
Perfecting motor with cogging and uniformity compensations
In addition to cogging torque, the new feature allows compensating also nonuniformity of torque production. I.e. if motor torque setpoint is kept constant and motor is being turned, it may produce variable amount of torque due to same reasons than cogging. Nonuniformity compensation will modulate the torque setpoint by a selected sine or cosine function and amplitude.
The new feature beta will become available for IONI Pro in the soon upcoming FW release. We hope that this will bring cost of any motor control system down as cheaper motor could achieve nearly same smoothness as expensive ones.
Thousands thanks for contributing premium name suggestions! After a lot of consideration we chose to go with IONI Pro HC ending after drive model because:
HC extension indicates about something additional to original model. We didn’t want to remove “Pro” from the name to avoid confusion.
Short and simple
Works also with non-pro version (IONI HC)
Logical and extensible, maybe we add IONI Pro HV (high voltage) someday
Oddly, Pro HC ending never crossed my mind, I was just thinking HC Pro which I didn’t like that much. Pro HC was suggested by Thomas in Facebook comments. Congratulations for your very first serial numbered IONI Pro HC drive!
We’ll keep the other names in reserve for possible future use. If your contribution is picked later, you will be rewarded for sure.
We’ve got our hands on the pilot run high current IONIs yesterday! Everything is working as expected which makes development straightforward.
Today I spent full day adapting the drive firmware, bootloader firmware and testing application to support the new hardware. It took some time to create a system where the one and only firmware runs on both hardware models. Firmware detects the underlying hardware model and automatically adjusts it’s operation accordingly.
Thank you for all the great name proposals! We are having difficult time choosing one among so many good options. The winner will be announced soon :)