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DC motor modeling with hands on
experiments on DSP2 learning module
(introductory lecture to mini project)
Doc.dr. Suzana Uran
University of Maribor,
Faculty of Electrical Engineering and Computer Science
Address : Smetanova 17, SI-2000 Maribor, Slovenia;
E-mail: [email protected] http://www.ro.feri.uni-mb.si
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Contents
• About DSP2 learning module
• DC motor modelling
– hands on exercise:
current controlled DC motor model (we look for
a model of current control loop )
• Conclusion
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Control system: DSP2 learning module
http://www.ro.feri.uni-mb.si/projekti/dsp2/
DSP2 card
Exchangeable Control Plant
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DSP2 card: short description
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Signal processor TI TMS320C32-60,
3 fast analog inputs 12 bit (2.6us conv. time)
8 MUX analog inputs 12 bit ,
1 analog bipolar output(12 bit)/2 unipolar outputs
1 PWM output (3 phase)
1 input for incremental encoder
3 digital outputs and 1 digital input (isolated)
RS 232 duplex communication port
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Control plant: DC/AC motor
http://www.ro.feri.uni-mb.si/projekti/dsp2/
H-bridge
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DC motor
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Control plant: Buck converter
buck
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RC oscilator: ADDA+RC control plant
http://remotelab.ro.feri.uni-mb.si/experiments_rc_oscilator.asp
also REMOTE experiment!
RC control plant
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DSP2 module: Rapid Control Prototyping
MATLAB/SIMULINK
and DSP Terminal on
Personal computer
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SIMULINK libraries for DSP2 learning module
http://www.ro.feri.uni-mb.si/projekti/dsp2/documentation/
DSP2_Library_for_Simulink.pdf
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Embedded Target for DSP-2 board
DSP2 learning module
DSP blockset
Standard SIMULINK libraries
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Modelling of DC motor current control loop
Hands on experiment:
Build a MATLAB/SIMULINK block scheme for
open loop control of current controlled DC
motor (ESCAP 28D2R-219P) using DSP2
learning module!
Measure motor speed with incremental
encoder.
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DC motor, load, encoder data
DC motor ESCAP 28D2R-219P with incr. encoder.
Nominal
voltage
Nominal
current
Nominal
speed
12 V
1.5 A
Torque
constant
Rotor inertia
19.5
mNm/A
1.76*10-6
kgm2
Load inertia
7.56*10-6
kgm2
144*4=576
p/rev
5000
rev/min
Incremental
encoder
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Getting started: DSP2 learning module
http://www.ro.feri.uni-mb.si/projekti/dsp2/documentation/
DSP2_Library_for_Simulink.pdf
• In MATLAB6p5/work directory create a new
directory named: VILLACHvisit
• Run MATLAB6p5 and go to VILLACHvisit
directory
• In MATLAB command window write
command: dsp2lib
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Getting started
In the new opened window ( see figure below)
double click New Model button and choose new file name!
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Getting started
A new SIMULINK file for work with DSP2 learning
module is opened with 3 buttons left above.
Now you can start building SIMULINK block scheme.
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Getting started
• In DSP2 learning module library
find blocks with name DCMOT
• choose block DCMOT tokovna
regulacija (DCMOT TOKREG Ia
– motor current control loop ) and
put it in your SIMULINK scheme
• choose block DCMOT meritev
hitrosti (DCMOT OMEGA –
motor speed measurement) and put
it in your SIMULINK scheme
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Getting started
In menu of your file choose:
Simulation/Simulation Parameters/Real-Time Workshop
For DSP-2 options 2 set:
576 number of lines per
revolution for Incremental
encoder
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Getting started
• In Embedded Target for DSP-2 board
library find block To Terminal – it is a
block for data visualisation on your PC
• use three blocks To Terminal as
shown on next slide
• In Embedded Target for DSP-2 board
library find block From Terminal – it
is a block for data input from keyboard
of your PC
•use two blocks From Terminal as
shown on next slide
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Getting started
Build SIMULINK block scheme below:
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Getting started
Set parameters on the left for
Pulse Generator block
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Getting started
• Double click Edit Parameters (blue button)
• Enter definitions for:
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T = 200e-6; % sampling time
amp (choose – carefully consider)
per (choose – carefully consider)
offset (choose – carefully consider)
• Double click Update Parameters (blue button)
• Switch on DSP2 learning module and double
click Build (blue button)
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Getting started
• after code buiding and download to DSP2 the DSP Terminal
program starts. FIRST set Ioff as below (middle value to 0)
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Getting started
After setting ENABLE=1, and selecting Ia, IaREF to view we get:
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Getting started
• Did you get the same response?
• What happens if we choose offset=0? WHY?
• Determine the order and parameters of the
model for the current control loop !
• If there is enough time left find the speed
response of DC motor!
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Motor speed response/Simulink
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Speed response
wm(rad/s)
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input signal
IaREF
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1
0
-1
0
0.01
0.02
0.03
0.04
time(s)
0.05
0.06
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0.08
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Conclusion
Current control loop is modelled as 1st order system.
Md
KT , TT
IaREF
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KM
1/JC
m
KM=0.0195 Nm/A
KT = 1,
TT = 0.9 ms
JC = 9.32. 10-6 kgms-2
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Motor speed measurement
Motor speed measurement is obtained from
position measurement of incremental encoder
by differenciation  is very noisy.
To filter out the noise we use :
2.nd order Butterworth filter with
fcutoff = 200 Hz.
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