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WorksheetsCA 3.4 QUIZ
Total questions: 30
Worksheet time: 15mins
Example of adjustable speed drives
Fan or pump flow process
Velocity and position control
Electric train
all the above
The switched reluctance motor is a
doubly salient, singly excited motor
singly salient, singly excited motor
doubly salient, doubly excited motor
singly salient, doubly excited motor
the advantages of Switched Reluctance
simple,low inertia
efficiency higher
no acoustic noise
all the above
switched reluctance motor rotor has
no windings,magnets and cages
only cages
only field coils
both magnets and cages
according to variable reluctance principle,when air gap min
both reluctance and inductance min
reluctance min ,inductance max
both reluctance and inductance max
no change in reluctance and inductance
In SRM the torque is produced due to
variable reluctance principle
mutual induction
self induction
constant reluctance
Switched reluctance motor means
Salient pole synchronous motor without excitation winding
A stepper motor with salient poles
Synchronous motors with salient poles on stator and rotor
A stepper motor with closed loop control and with rotor position sensor
Increasing the stator poles ___________ the speed of Reluctance motor.
a) Decreases
b) Increases
c) Remains the same
d) Negative
Energy ratio =
Wm/[Wm + R] = 10
Wm/[Wm + R] = 0.455
Wm/[Wm + R] = 999
Wm/[Wm - R] = 0.455
Disadvantage of Two Power Semiconductor Switching Devices per phase and two diodes
Higher number of switches required in each phase, which makes the converter expensive and also used for low voltage applications
The common switch conducts for all the phases and thus has higher switching stress.
A poor utilization of copper.
Freewheeling is not possible during chopping as the phases have -Vdc. this causes of higher ripples in current and torque during chopping.
The microprocessor or computer controller can perform the following functions.
a) Control the feedback loops.
b) PWM or square wave signal generation to inverters.
c) Optimal and adaptive control.
d) all the above
the stator pole different from rotor poles,because of
eliminate losses
reduce cu usage
self starting
small size
switched reluctance motor is used in
variable speed drives
fixed speed dives
both variable and fixed drives
none of the above
A switched reluctance (SR) motor
stator have salient poles
rotor have salient poles
both stator and rotor have salient poles.
both stator and rotor have not salient poles.
when aligned with position
inductance will be max
inductance will be min
no change in inductance value
inductance=0
hysteresis type controller used to
voltage control
angle control
A and B
current control
RPS used to
sense the rotor position
measure input value
measure the stator position
none of the above
Torque proportional to
i/2
i2
2i
i
shaft position sensor used for SRM
photo transistors
photo diode
diode
A and B
Advantage of sensor less operation
no mechanical connection
only electrical measurements
reliable,precious
all of the above
Why rotor position sensor is essential for the operation of Switched Reluctance motor?
communication and speed feedback.
step control
torque prediction
all the above
SRM stator made up of
germanium
cast iron
silicon steel
copper
In which of the following motors DC excitation is not required?
(a) hysteresis motor.
(b) reluctance motor.
(c) synchronous motor.
(d) none of the above.
field coils of opposite poles connected in
series
parallel
series or parallel
none of the above
A switched reluctance motor differs from a VR stepper motor in the sense that it
(a) has rotor poles of ferromagnetic material
(b) rotates continuously
(c) is designed for open-loop operation only
(d) has lower efficiency.
When do you go for chopping mode of control in switched reluctance motor?
low-speed
high-speed
constant speed
moderate speed
in left hand rule mid finger denotes
current
field
emf
direction
SRM is
not a self starting
discrete motor
a self starting
all the above
in dynamic equilibrium(steady state)
developed torque = load torque
developed torque >load torque
developed torque < load torque
developed torque <= load torque
one of the requirement of selecting power converter is each phase of the SRM independent of the other phase
true
false
