Design considerations: Power semi-conductor devices Gate drive design Busbar and snubber circuits High power DC chopper example
J. Wang 2010-10-25
Ideal Switching Device
When switch is on (closed) When switch is off (open)
vS = 0 iS = 0
Plane of coil
Plane of coil
Transients associated with
Generator initially unloaded
then 3 short circuit on
5th Ed., F,K & U
6th Ed., F,K & U
5th Ed., F,K & U
a = Laa * ia + Lab * ib + Lac * ic + Laf * i f
b = Lba * ia + Lbb * ib + Lbc * ic + Lbf * i f
c = Lca * ia + Lcb * ib + Lcc * ic + Lcf * i f
f = L fa * ia + L fb * ib + L fc * ic + L ff * i f
Specify the type of electric motor that will
meet the following requirements best
provide constant speed under all loads
provide an easily adjusted speed which remains nearly constant (within
10%) over a wide range of loads
operate from ordinary house cur
Existing Capacity by Energy Source, 2008
Natural Gas3 .
Hydroelectric Conventional5 .
Solar Thermal and Photovoltaic
ee643, exam #2, au '96
1. This question is related to a salient pole 60 Hz synchronous motor with a squirrel cage winding on the
rotor which is used for starting purposes.
(a) What is the frequency of the current in the squirrel cage rotor conductors imme
ECE 643 Exam #2 Autumn 2010 Mon. Nov. 22, 2010
The exam will be open book and closed notes.
The material covered in the exam will generally be based on topics discussed in class and principles
illustrated in the homework, with a lesser emphasis on materia
dWelec = dWfld + dWmech
dWelec = i dl
dWfld = i dl - f dx
dWmech = f dx
In general, the differ
cos t 0 cos t 0 2 cos t 0
Tabc_dq0 t 0 sin t 0 sin t 0
sin t 0
| E | *|V |
| V | *( X X )
* sin( )
* sin( 2 * )
2* X * X
Eaf =Va +Ia*Ra +Ia*jXq
Ls * Laa 0 Lal
ECE 643 Homework #1 due Fri., 01 Oct. 2010
1. Refer to the circuit given below; the parameters and the variables are in per unit.
Maintain the magnitude of the current at 1.0 per unit, while varying the angle of the current
from +450 through 00 to -450. P
Series-connected universal machine.
Typical torque-speed characteristics
of a series universal motor.
Schematic view of a single-phase
Shaded-pole induction motor and typical torque-speed characteristic.
EE 643 Exam #1 Autumn 2010 Mon. Oct. 25, 2010 The exam will be open book and closed notes.
The material covered in the exam will generally be based on topics discussed in class and principles illustrated in the homework, with a lesser emphasis on material
1. Refer to Prob. #1.17, page 48 of the text. Instead of the questions as formulated in the text,
using r = 3200 and N = 100 turns, determine the air gap length, g, so that the inductance of the
coil is 1.5 mH. Use core
1. Prob. 4.9, page 239 of text.
powerangle curves requested in the problem, you will need to calculate the value o
This falls under the category of paper reviews. The following is a list of IEEE standards that can be
accessed via IEEEXplore [http:/www.ieeexplore.ieee.org from a university connected
Speed control by means of line voltage.
Speed control by means of rotor resistance.
curves showing effect
of changing rotor-circuit
Figure 6.16 [FK&U 6th Ed.]
Principles of the pole-chan
Fig. 6.1 Cutaway view of a
three-phase induction motor
with a wound rotor and slip
rings connected to the threephase rotor. (General Electric
Fig. 6.2 Cutaway view of a
three-phase squirrel-cage motor.
The rotor cutaway shows the
Induction machine basic torque relationship:
Therefore, the relationships at maximum
(breakdown) torque are:
3 *V1a * R2 s
s ( Re1 + R2 s ) 2 + ( X e1 + X 2 ) 2
s Re1 + ( Re1 ) 2 + ( X e1 + X 2 ) 2
By neglecting s
M otor action
For Generator Action flow is from mechanical to electrical.