ELECTRIC DRIVES
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Transcript ELECTRIC DRIVES
ELECTRIC DRIVES
CONVERTERS IN ELECTRIC DRIVE SYSTEMS
MODULE 2
Dr. Nik Rumzi Nik Idris
Dept. of Energy Conversion, UTM
2009
CONVERTERS - Module 2
AC-DC controlled rectifier
approximate model
SIMULINK examples
open-loop
closed-loop
Switch Mode DC-DC
converter
2-Q and 4-Q converters
Small signal modeling
unipolar
bipolar
SIMULINK example
Current-controlled for SM
converters
Bridge converter
hysteresis
fixed frequency
3-phase VSI
hysteresis
PI controller
Current-Controlled Converters
Current need to be controlled (in drives):
To control the torque
To limit the current – protect the switching devices
Example of current control in cascade control structure
*
+
*
+
position
controller
T*
speed
controller
+
current
controller
kKTt
1/s
Motor
converter
Current-Controlled Converters
ON-OFF Controllers
Separated PWM block
Hysteresis
PI controllers
Non-linear
controllers
Linear
controllers
Current-Controlled Converters
Hysteresis-based
+
ia
Vdc
+
ia
Va
−
va
iref
ierr
q
q
ierr
Current-Controlled Converters
Hysteresis-based - extending to 3-phase system
i*a
i*b
i*c
+
Converter
+
+
Motor
Current-Controlled Converters
Hysteresis-based - extending to 3-phase system
• High bandwidth, simple implementation, insensitive to parameter variations
• Variable switching frequency – depending on operating conditions
• Instantaneous error for isolated neutral load can reach double the band
For isolated neutral load, ia + ib + ic = 0
control is not totally independent
iq
is
h
h
id
h
h
Current-Controlled Converters
Hysteresis-based – simulink block
VSI
Hysteresis
comparators
References
Load
Current-Controlled Converters
Hysteresis-based – simulation results
Current error
Actual and reference currents
0.5
10
0.4
0.3
5
0.2
0.1
0
0
-0.1
-0.2
-5
-0.3
-0.4
-0.5
-10
0.005
0.01
0.015
0.02
0.025
-0.5
0.03
-0.4
-0.3
-0.2
-0.1
0
0.1
0.2
0.3
10
5
0
Actual current locus
-5
-10
-10
-5
0
5
10
0.4
0.5
Current-Controlled Converters
Hysteresis-based – simulation results
0.5
0
-0.5
2
2.2
2.4
2.6
2.8
3
3.2
3.4
3.6
3.8
4
-3
x 10
0.5
0
-0.5
2
2.2
2.4
2.6
2.8
3
3.2
3.4
3.6
3.8
4
-3
x 10
0.5
0
-0.5
2
2.2
2.4
2.6
2.8
3
3.2
3.4
3.6
3.8
4
-3
x 10
2
0
-2
2
2.2
2.4
2.6
2.8
3
3.2
3.4
3.6
3.8
4
-3
x 10
2
0
-2
2
2.2
2.4
2.6
2.8
3
3.2
3.4
3.6
3.8
4
-3
x 10
2
0
-2
2
2.2
2.4
2.6
2.8
3
3.2
3.4
3.6
3.8
4
-3
x 10
Current-Controlled Converters
PI-based
Vdc
iref +
PI
vc
vc
vPulse
width
tri
modulator
qqq
Current-Controlled Converters
PI-based – extending to 3-phase
i*a
i*b
i*c
+
PI
PWM
Converter
+
PI
+
PWM
PI
PWM
• Sinusoidal PWM
• Interactions between phases only require 2 controllers
• Tracking error
Motor
Current-Controlled Converters
PI-based
• Perform the 3-phase to 2-phase transformation
- only two controllers (instead of 3) are used
• Perform the control in synchronous frame
- the current will appear as DC
• Interactions between phases only require 2 controllers
• Tracking error
Current-Controlled Converters
PI-based
i*a
i*b
i*c
+
PI
PWM
Converter
+
PI
+
PWM
PI
PWM
Motor
Current-Controlled Converters
PI-based
i*a
PI
i*b
SVM
2-3
3-2
Converter
PI
i*c
3-2
Motor
Current-Controlled Converters
PI-based
va*
id*
PI
controller
+
iq* +
iq
id
dqabc
PI
controller
vb*
SVM
or SPWM
VSI
vc*
s
Synch speed
estimator
s
abcdq
IM
Current-Controlled Converters
PI-based – simulation with control in stationary frame
Simulink and SimPowerSystems
+
v
-
idref
ia_s
va
Voltage Measurement To Workspace1
To Workspace5
To Workspace4
Load
Scope
Sine Wave
PID
Product
abc
dq0
sin_cos
Sine Wave1
abc_to_dq0
Transformation
Product1
PID Controller1
In1 Out1
i
-
+
PID
Series RLC Branch
Subsystem3
Current Measurement
PID Controller2
g
+
Sine Wave2
DC Voltage Source
Product2
Out1
A
+
B
Series RLC Branch1
i
-
Current Measurement2
C
Universal Bridge
Subsystem5
+
Series RLC Branch2
Step
abc
32
transformation
dq0
sin_cos
abc_to_dq0
Transformation1
Out1
Subsystem1
References
PI
controllers
VSI
32
transformation
i
-
Current Measurement1
Current-Controlled Converters
PI-based – simulation with control in stationary frame
d and q current components viewed in rotating frame
ia as viewed in stationary frame
4
3
3
2
2
1
1
0
0.01
0
0.011 0.012 0.013 0.014 0.015 0.016 0.017 0.018 0.019
0.02
-1
0.5
-2
-3
0.03
0
-0.5
-1
0.01
0.011 0.012 0.013 0.014 0.015 0.016 0.017 0.018 0.019
0.02
0.035
0.04
0.045
0.05
0.055
0.06
0.065
0.07
Current-Controlled Converters
PI-based – simulation with control in synchronous frame
Simulink and SimPowerSystems
ia_r
+
v
-
va
Voltage Measurement
To Workspace1
To Workspace4
Scope
Sine Wave3
PID
Product
Series RLC Branch
Out1
Sine Wave4
In1 Out3
Product1
Out4
Current Measurement1
Subsystem3
PID
PID Controller2
Subsystem6
Sine Wave5
i
-
+
In1 Out1
PID Controller1
+
Product2
-
g
A
i
-
+
Series RLC Branch1
Current Measurement
B
C
Universal Bridge
DC Voltage Source
+
Series RLC Branch2
Step
d_q
a_b_c
Subsystem1
i
-
Current Measurement2
Current-Controlled Converters
PI-based - simulation with control in synchronous frame
d and q current components viewed in rotating frame
ia as viewed in stationary frame
4
3
3
2
2
1
1
0
0.02
0.025
0.03
0.035
0.04
0.045
0
-1
0
-2
-0.5
-1
0.02
-3
0.03
0.025
0.03
0.035
0.04
0.045
0.035
0.04
0.045
0.05
0.055
0.06
0.065
0.07