CHARACTERIZATION OF SENSORLESS MOTOR CONTROL TECHNOLOGY USING
In recent years, power electronics and microelectronics have seen groundbreaking advancements
with the application of electric drive systems and motor control technologies, permeating almost
all aspects of modern life from transistors, capacitors, washing machines, and air conditioners to
elevators, motor vehicles, monorails and centrifuges. Today’s Microcontroller Units (MCUs) bring
great precision, efficiency, and lowered costs to a wide range of applications including appliances
with blowers and compressors such as washers and refrigerators, HVAC (Heating, Ventilation and
air Conditioning Systems), as well as automotive control systems.
TI’s InstaSPIN™ enables designers to identify, tune, and fully control any type of three-phase,
variable speed, sensorless, synchronous or asynchronous motor control system. It uses TI’s new
software encoder, a sensorless FAST™ (Flux, Angle, Speed and Torque) observer, embedded in
the read-only-memory (ROM) of Piccolo devices.
Dave Wilson, Senior Motor Systems Engineer with the C2000 group, was tasked with a project
to characterize the FAST™ observer and develop a datasheet for it. He tried to do this by setting
up a dynamometer (dyno) system with a circuit board to control it. He intended to characterize
the FAST™ observer by varying the error in some of the gain terms and observe its performance.
This presented a challenge, as not only was it a slow and tedious process due to output variances
over time and temperature changes, it also required constant recalibration. Additionally, the
electromagnetic torque could not be measured on the dyno, only the shaft torque could. This was
a problem since the software could not be properly tested as the hardware he was using was not
adequately equipped to test it.
“A key benefit to using Altair Embed for
this project is its code generation
capability and how quickly and
fast it works. The speed of how
its drivers work and being able to
interface directly with our ROM
code was really the key enabler for
me, and that was the most important
benefit in this particular project.”
Senior Motor Systems Engineer, C2000 Group,
ALTAIR EMBED IN THE SIMULATION PROCESS - DEVELOPMENT OF ALTAIR EMBED
SIMULATION OF ENTIRE SYSTEM
Mr. Wilson had first become familiar with Altair Embed while viewing a web based
presentation 4 years prior. Recalling how easy it was to use, he decided to try it for his current
project. Altair Embed provided him with a solution to create fast and accurate simulations of motor
analog dynamics as well as the digital control. He was then able to automatically create C code
from the controller portion of his graphical diagram, and download the code to run on the
Piccolo target. Using the Altair Embed JTAG Hotlink in a new synchronous mode, Mr. Wilson could
run the motor simulation in lock step with the control running on the target in non real-time.
This allowed Mr. Wilson to verify controller operation against any motor configuration, no matter
how big or small. It also allowed him to take part of the simulation and interface it to the
FAST™ observer. He developed an Altair Embed simulation of the entire system except for the FAST™
piece of code. He could now control any gains he liked. Different parameters like resistances,
inductances, controller gains and voltage tolerances could now be controlled as well. “I could
then characterize what the FAST™ observer in ROM would give me, and I could compare that
to the ideal answer from the simulation. The bottom line is, Altair Embed completely solved the problem
that I was running into,” said Mr. Wilson, “A key benefit to using Altair Embed for this project is its code
generation capability and how quickly and fast it works. The speed of how its drivers work and
being able to interface directly with our ROM code was really the key enabler for me, and that
was the most important benefit in this particular project,” he concluded.
BENEFITS AND OUTCOME - GENERATION OF FAST™ TRM
Deriving the solution using Altair Embed not only allowed generation of the FAST™ TRM (Technical
Reference Manual), it also resulted in a very useful tool. A tool which can enable TI’s customers
to test their motor control requirements using TI’s actual ROM based algorithm that they would
have never before been able to do without having to hook up an actual motor system. This gives
them a quick way to kick the tires on InstaSPIN™ FOC (Field Oriented Control) without having
to build a whole system for it.