Download The review outline of power electronics

The review outline of power electronics
Exam type：
Single choice items：10 questions 20 points
Short answers: 5 questions 20 points
Draw waveform or circuit diagram: 2 questions 10 points
Calculation: 5 questions 50 points
1、 Classification of power converters；
2、 For this controlled devices：Thyristor、GTO、GTR、MOSFET、
IGBT， according to the device’s classification, half-controlled
device;
fully-controlled
device;
current-driven
device;
voltage-driven devive.
3、 What is the condition of thyristor in conduction？How can
change the conducting thyristor to turn off？
4、 random waveform , thyristor current is known, how to
calculate its average value and RMS value.
5、 Select safety margin，calculate rated voltage and rated
current of thyristor.
6、 Single-phase, half-controlled rectifier, inductive load, what is
the effect in parallel with a freewheeling diode across the
load？
7、 Single-phase half-wave controlled rectifier, resistive load,
what is the range of delay angle  ？
8、 Single-phase bridge，fully-controlled rectifier，inductive or
EMF load，L is large enough.
（1）The range of delay angle with resistive load or inductive load；
（2）Please draw
ud and i2 waveform.
（3）Calculate average output voltage U d 、 I d 、 I dVT , RMS I 2
IVT .
（4）Select safety margin，calculate rated voltage and rated current
of thyristor.
（ 5 ） The maximum reverse voltage that the thyristor can
withstand.
9、 What are the similarities and differences of single phase
bridge fully-controlled rectifier and single phase full-wave
rectifier?
10、 Three phase ，half wave （controlled） rectifier，inductive
or EMF load，L is large enough.
（1）
The range of delay angle with inductive load；
（2）
The range of delay angle with resistive load when current
is continuous；
（3）Please draw
ud and id iVT
waveform.
（4）Calculate average output voltage U d 、 I d 、 I dVT , RMS
IVT .
（5）Select safety margin，calculate rated voltage and rated current
of thyristor.
（ 6 ） The maximum reverse voltage that the thyristor can
withstand.
11、 Three phase bridge，fully-controlled rectifier，inductive or
EMF load，L is large enough.
（3）
The range of delay angle with inductive load；
（4）
The range of delay angle with resistive load when current
is continuous；
（3）Please draw
ud and id iVT
i2 waveform.
（4）Calculate average output voltage U d 、 I d 、 I dVT , RMS IVT I2.
（ 5 ） The maximum reverse voltage that the thyristor can
withstand.
12、 The expression of U d by delay angle or inversion angle.
13、 Three control methods of DC/DC chopper；Three basic circuit
diagrams. Calculate output average U o and average I o ,
input average I1 .
Draw the waveform of load’s io and uo in buck chopper.
14、 In the current reversible chopper circuit, Which devices are
consist of Boost chopper or Buck Chopper？
15、 In power electronics ， commutation means the current
flowing through one branch to another branch. Four type
commutation.
16、 What is the waveform of SPWM？How to achieve variable
voltage and variable frequency of SPWM modulation
method ？
17、 What are the necessary conditions for the inverter mode
operation of controlled rectifiers？What is the inversion
failure？Which reasons can cause inversion failure？which
circuit can not use in active inverter circuit.
18、 The range of minimum inversion angle.
19、 What are the features of VSI.
20、 Single-phase bridge voltage source inverter circuit, uni-polar
or bi-polar PWM method, the DC voltage is U d ，the level of
output voltage wave of the inverter
21、 Three-phase bridge voltage source inverter circuit, 180°
conduction method, the DC voltage is U d ，the level and
waveform of line to line voltage uUV and phase voltage uUN
wave of the inverter.
22、 What are the similarities and differences of AC voltage
controller and AC power controller? What is the power
electronics switch?
23、 What is the meaning of power electronic switch using high
frequency?
24、 What are the effects of transformer leakage inductance on
rectifier circuits?（There has not calculate question）
25、 Single phase AC-AC frequency converter circuit to work
without circulating, R-L load, given that converter circuit is in
the rectifier state, the direction of output voltage and output
current； uo  0 , io  0 is given, the state of the circuit
26、 Synchronous and asynchronous modulation.
27、 Draw waveform or circuit diagram:
（1）
Three-phase bridge ， fully-controlled rectifier ，
inductive load，L is large enough，please draw the
waveform of output voltage ud when   0o ;30 ;60o
（2）
Please draw uni-polar or bi-polar PWM waveform;
（3）
Three-phase half-wave controlled rectifier，   0 .If
“A” phase trigger pulse disappeared，please draw
the waveform of ud when load was resistive or
inductive（L is large enough.
（4）
Please draw the three-phase bridge fully controlled
rectifier（resistive load）circuit diagram, label every
device sequence number.
（5）
Please draw the three-phase bridge voltage source
inverter
circuit
diagram,
label
every
device
sequence number.
（6）
Please draw the single phase AC/AC voltage
controller main circuit diagram.
As follows, there are calculation questions.
28、
Three-phase bridge（or single phase bridge）
，fully-controlled
rectifier，inductive load，L is large enough，R ， ，RMS U 2
is known.
（1）Calculate the load’s active power；
（2）Calculate Distortion factor （
=I1
/ I）
、Displacement
factor（1= cos1）and PF(power factor) of i2.
（3）Calculate the THDi of i2 and the RMS current of some
times harmonic.
29、 Fill the device which is labeled by number in the block;
Calculate output average U o and average I o , input average I1 .
Draw the waveform of load’s io and uo （buck chopper）
；
Describe the operation principle of it.
30、 Single-phase AC/AC voltage controller, inductive load, R ，
X L orL isknown，f=50HZ，U1=220V.
Calculate or draw waveform;
（1） The range ofelay angle  ；
（2） The maximum load’s RMS current；
（3） The maximum output power and the power factor of
source side in this time；
（4） Please draw the main circuit.
31、 Rectifier circuit，inductive or EMF load，L is large enough.
（1）Please draw
ud and id iVT
i2 waveform.
（2）Calculate average output voltage U d 、 I d 、 I dVT , RMS IVT I2.
（ 3 ） The maximum reverse voltage that the thyristor can
withstand.
（4）Select safety margin，calculate rated voltage and rated
current of thyristor.
32、Three phase VSI(Voltage source inverter)，180°conduction
method，DC side Ud is known.
（1）Please draw the waveform of line to line voltage uUV and
phase voltage uUN ；
（2）Calculate the output RMS UUV 、 UUV 1 and UUN 、 UUN1 ；
（3）
Calculate RMS voltage of some times harmonic（ UUV 5、7 ）.
33、Single-phase VSI（Voltage source inverter.
（1）Please draw Un-polar or bi-polar PWM waveform；
（2）Describe the operating principle of uni-polar or bi-polar
PWM waveform producing.