University of Saskatchewan
Department of Electrical and Computer Engineering
EE 443.3 Power Electronics
X'inal Examination
Time: 3 hours
Notes: (a) This is a closed book examination. Formula sheets are attached.
(b) Record in your cnswer book(s) all neces
University of Saskatchewan
Department of Electrical Engineering
EE 344.3 Power Electronics
Final Examination
Time: 3 hours
Notes: (a) This is a closed book examination. Formula sheets are attached.
(b) Record in your answer book(s) all necessary steps and
University of Saskatchewan
Department of Electrical and Computer Engineering
EE 343.3 Power Electronics
Assignment 2
Inst: N. Chowdhury
September 21, 2015
=
Show all necessary steps and calculations. Use graph papers for all sketches.
1. In the following
University of Saskatchewan
Department of Electrical and Computer Engineering
EE 443.3 Power Electronics
Final Examination
Time: 3 hours
Notes: (a) This is a closed book examination. Formula sheets are attached.
(b) Record in your answer book(s) all necess
Q.2
Thyristor Q in Fig. 4.9 is fired at a = 40 Deg. The diode D acts as a freewheeling diode. The
voltage drops across Q and D can be considered zero during conduction. The supply is
2 V sin (t) V, and R = 1.7 W , L = 12 mH and w = 377 rad/sec. Vc = 12 V
Solution for
EE 343 Assignment 4
Instructor: N. Chowdhury
Marker: Shenyi Liu
1.
(a)
Vc =48 V, R = 2.1 , L = 10 mH, = 50o = 0.872 rad.
L =120x0.01 = 3.77
R
0.557
L
Z= R 2 L2 4.315
= tan1 = (L/R) = 60.88 o =1.062 rad
Voltage at the transformer secondary
Solution for
EE 343 Assignment 4
Instructor: N. Chowdhury
Marker:Shenyi Liu
1.
(a)
Vc =48V, R = 2.1 , L = 10mH, = 50o = 0.872 rad.
L =120x0.01 = 3.77
R
0.557
L
Z= R 2 L2 4.315
= tan1 = (L/R) = 60.88 o =1.062 rad
Voltage at the transformer secondary sid
Singlephase Inverters
Halfbridge
Disadvantage: A threewire dc source is
required.
Two identical capacitors are required.
Gating signals and output voltage of a
singlephase halfbridge inverter
Antiparallel diodes, D1 and D2
Load current may not revers
University of Saskatchewan
Department of Electrical and Computer Engineering
EE 343.3 Power Electronics
Assignment 4
Inst: N. Chowdhury
October 7, 2015
=
1. A singlephase, fullwave, phasecontrolled rectifier is shown in Figure 1. For R = 2.1 , L
= 10 m
Power Electronics
EE 343.3
Assignment 2
Instructor: N. Chowdhury
Marker: Shenyi Liu
Solution (1)
(a)
v
ig
t
t
i
vo
VAK
t
t
t
(b)
=
i
vi
Z
sin(t ) + Ae 0.9284t
Z= 2 + ()2=5.144
=atan(wL/R)=0.8225
i = 32.99 sin(t ) + Ae 0.9284t
At t= = 45 degrees, i=0,
A =
University of Saskatchewan
Department of Electrical and Computer Engineering
EE 343.3 Power Electronics
Assignment 3 (Design)
Inst: N. Chowdhury
September 30, 2015
=
Design a singlephase fullwave rectifier with the following specifications that will be
Average load voltage VO may be
varied in one of the following three
ways:
1. tON may be varied while time period,
T is held constant Pulsedwidth
Modulation
2. tON may be kept constant while T is
varied Frequency Modulation
3. Combined Pulsedwidth and
Fr
University of Saskatchewan
Department of Electrical and Computer Engineering
EE 343.3 Power Electronics
Assignment 1
Instructor: N. Chowdhury
September 11, 2015
=
1. In the circuit shown in Figure 1, the switch is closed at t = 0. Obtain a time dependent
1
BOOST CHOPPER
Figure 1: Boost Chopper
Inst. N. Chowdhury
EE 344.3
2
Continuouscurrent Mode
Figure 2 shows the steadystate
waveforms for continuouscurrent mode
where the inductor current flows
continuously.
Figure 2: Steadystate waveforms of the
Current in a Singlephase Fullwave Rectifier
Consider the following singlephase fullwave rectifier circuit shown in Figure 1. Figure
2 shows an equivalent model of the rectifier shown in Figure 1. The equivalent model
can be utilized to analyze output
University of Saskatchewan
Department of Electrical & Computer Engineering
EE 443.3 Power Electronics
Midterm Examination
Instructor: N. Chowdhury
February 16, 2011
Time: 2 Hours
Notes:
(a) This exam booklet has total 11 pages.
(b) This is a closed book e
A Fullbridge Singlephase Inverter
iS
+
iQ1
Q1
iQ4
Q4
D1
iG1
iQ2
Q2
+
iQ3
Q3
D2
iG2

LOAD
iG3
iD2
iD4
D4
iG4
iO
V

iD1
D3
iD3
iG1
iG3
t
iG2
iG4
T/2
T
t
V
Output
Voltage
t
V
A Singlephase Bridge Inverter with Gating
Signals and Output Voltage
Power Electronics
EE 343
Assignment 3
Instructor: N. Chowdhury
Marker: Shenyi Liu
Solution (1)
(a)
v
ig
t
t
i
vo
VAK
t
t
t
(b)
i
vi
Z
sin(t ) Ae0.9284t
Z= 2 + ()2=5.144
=atan(wL/R)=0.8225
i 32 .99 sin( t ) Ae 0.9284t
At t= = 45 degrees, i=0,
A 32 .99 sin
1
BOOST CHOPPER
The output voltage of a boost chopper is always greater than the input voltage. Figure 1.
shows a boost chopper. When the switch is on, the diode is reversed biased, thus isolating
the output stage. The input supplies energy to the induc
Snubber Circuits
Protection of switching devices and circuits: Switching devices and circuit components
may fail due to the following reasons.
1. Overheating thermal failure
2. Overcurrent
3. Overvoltage usually happens during turnoff
di
4. Excessive
dt
University of Saskatchewan
Department of Electrical and Computer Engineering
EE 343.3 Power Electronics
Assignment 3
Inst: N. Chowdhury
September 26, 2016
=
Show all necessary steps and calculations.
1. In the following circuit (Fig. 1), R = 3.5 , L = 10
Forced Commutation
D1
Ls
T1
A
D2
L
Ra
+
C
T3
Vs
Dm
La
Resonant Pulse Chopper
Figure 1: Resonant Pulse Chopper
Im
current through T1
t
0
Vc
C
L
current through T3
0
Im
0
t
t1
current through
t6
t2
D2
t
current through D 1
0
Im
t3
current through
0
t
t4
Dm
University of Saskatchewan
Department of Electrical and Computer Engineering
EE 343.3 Power Electronics
Assignment 2
Inst: N. Chowdhury
September 19, 2016
=
1. In the following circuit, v i 110 2 sin t , = 377 rad/sec, R 2 and
L 11 mH . Switch SW is close
University of Saskatchewan
Department of Electrical and Computer Engineering
EE 343.3 Power Electronics
Assignment 6
Instructor: N. Chowdhury
November 20, 2015
=
1. A singlephase fullbridge inverter (Figure 1) is required to have an output voltage
wavef
University of Saskatchewan
Department of Electrical and Computer Engineering
EE 343.3 Power Electronics
Assignment 5
Instructor: N. Chowdhury
November 2, 2015
1. In the Type A chopper shown in Figure 1, V = 600 V, L = 5 mH, R = 2 , Vc = 240 V, T
= 2 ms, a