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Closing the current loop

The purpose of this step is to close the current loop and to set the PI regulators correctly to get a stable system while the motor is still running in speed open-loop.

Current Sensing

Key Modules:

In addition to the modules already used, we use the PI module:

  • PIDREG3 (Proportional Integrator Derivative regulator): This module regulates the two currents id and iq, generated in the Park module.
  • Open the PMS_Motor_level3.mdl Simulink model.
Figure 11: Closing the Loop with the PI

Vd Testing

  1. Run the model and double-click the “Stator Current” and “Rotor Speed” (same as previous section) and “Vd/Vq” scopes.
Stator Current

Rotor Speed
Ramp GeneratorVq Testing

Vd/Vq

For ease of use, the default PID parameters are already tuned. You can still play with them and observe the results. Within the watch windows, the PID coefficients are displayed for both iq and id. Using the following picture will help you to interpret the variables.

The speed measurement-encoder

During this step we will check the encoder feedback and we will align the calculated angle with the shaft angle.

The Speed Measurement Encoder

KEY MODULES:

In addition to the modules already used, we use:

  • QEP (Quadrature encoder pulse module): instance qep1. This module initializes the QEP DSP unit. This involves the associted timer (T2) set-up, the QEP DSP pins set-up and so on. Calling the initialization routine of the QEP module, the dedicated DSP registers are automatically configured with no waste of time for the user in reading through the documentation. This module outputs an electrical angle stored into the qep1.theta_elec variable which is then passed into the speed calculator module. The encoder mounted on the motor is a 2000 lines encoder. In addition to the traditional QEP signals (QEP1 and QEP2), it provides an index pulse, which toggles every complete mechanical round. This index is connected to the capture interrupt 3 of the DSP. In the corresponding served interrupt, we clear the timer 2 counter ensuring to keep it between 0 and 8000: this way we have a precise information on the rotor position. The QEP module also takes care of the capture unit initialization.
  • SPEED_MEAS_QEP (Speed measurement based on QEP information): instance speed1. Based on system information (number of poles pairs for instance), this module outputs the motor speed information.
  • Open the PMS_Motor_level4 Simulink model.
    Figure 16: Using the QEP
  1. Run the model and double-click the “PWM dutycycles” and “Rotor Speed” scopes.
PWM Duty Cycles
Rotor Speed

Align the sensed angle we the motor shaft.

Until now, the magnetic field in the motor was generated without taking care of the shaft position. Even if our motor is a synchronous motor, with no load and at load speed, it was easy to expect the shaft to start and to catch the magnetic field without problem. Now, if we want to close the speed loop, we need to know the shaft angle at every moment. The shaft position is given by the encoder but we still have to align the initial sensed position with the shaft.

For this, we use the Data Log module to display in real time the rmp_out variable (angle we used until now to create the magnetic field) and theta_elec (sensed angle).

Speed closed loop

Speed Closed Loop

The purpose of this step is to verify the speed regulator, close the speed loop and tune up the gains for the speed regulator if necessary. All the modules previously described are used in this final step.

Real time

The real-time software will run in the following hardware:

  • eZdsp F2812 (DSP control board based on the F2812)
  • DMC 550 (power stage board for BLDC and PMSM from Spectrum Digital®)
  • PMSM from Applied Motion Product ®

For safety reason it is mandatory that you strictly respect the following picture to connect the DMC 550.

Hardware Setup

During this build, the speed reference will be given to the DSP through a potentiometer placed on the DMC 550 (R66). To start with, please put the potentiometer around its midle position.

  1. MAKE SURE that the potentiometer is around its midle position
  2. Generate the code in Simulink
  3. Turn ON the PSU and set the voltage to 10V.

The motor should have good response time now thanks to the speed closed loop. As usual the PID controller is already tuned. Using the same graphical display we used during the lab 4 you can see the impact of the PID parameters.

Since all the kits are different, the default settings for the current and speed PID may not be suitable and the maximum command may be instable

Moving the speed potentiometer, you can appreciate the fast and smooth response time!

To stop the system properly

  1. Turn OFF the PSU
  2. Halt the DSP: From the pull-down menu, “Debug” → “Halt”;
  3. Close the Model

Questions & Answers

anyone know any internet site where one can find nanotechnology papers?
Damian Reply
research.net
kanaga
Introduction about quantum dots in nanotechnology
Praveena Reply
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
Bharti
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
Daniel
how to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
Maciej
characteristics of micro business
Abigail
for teaching engĺish at school how nano technology help us
Anassong
Do somebody tell me a best nano engineering book for beginners?
s. Reply
there is no specific books for beginners but there is book called principle of nanotechnology
NANO
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
s.
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
Tarell
what is the actual application of fullerenes nowadays?
Damian
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
Tarell
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
Virgil
is Bucky paper clear?
CYNTHIA
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
NANO
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Harper
Do you know which machine is used to that process?
s.
how to fabricate graphene ink ?
SUYASH Reply
for screen printed electrodes ?
SUYASH
What is lattice structure?
s. Reply
of graphene you mean?
Ebrahim
or in general
Ebrahim
in general
s.
Graphene has a hexagonal structure
tahir
On having this app for quite a bit time, Haven't realised there's a chat room in it.
Cied
what is biological synthesis of nanoparticles
Sanket Reply
what's the easiest and fastest way to the synthesize AgNP?
Damian Reply
China
Cied
types of nano material
abeetha Reply
I start with an easy one. carbon nanotubes woven into a long filament like a string
Porter
many many of nanotubes
Porter
what is the k.e before it land
Yasmin
what is the function of carbon nanotubes?
Cesar
I'm interested in nanotube
Uday
what is nanomaterials​ and their applications of sensors.
Ramkumar Reply
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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Source:  OpenStax, From matlab and simulink to real-time with ti dsp's. OpenStax CNX. Jun 08, 2009 Download for free at http://cnx.org/content/col10713/1.1
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