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起止时间:2021-03-10到2021-06-28
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Introduction of power electronics and devices Chapter 1 Test
1、 Which of the following power electronic devices has the highest switching frequency?
A:SCR
B:GTR
C:IGBT
D:POWER MOSFET
答案: POWER MOSFET
2、 Which one does not belong to the advantages of power electronic devices?
A:When the device turns off, it can withstand high terminal voltage and the leakage current is approximately zero
B:When the device turns on, it can carry a large current, and the terminal voltage is approximately zero
C:The device can work in amplified state
D:The current can only flow through in one direction
答案: The device can work in amplified state
3、 Wide bandgap semiconductor material is used for making new power electronic switches, which of the following descriptions does not belong to its advantages?
A:High withstand voltage
B:Higher on-state resistance
C:Better thermal conductivity
D:Better thermal stability and strong radiation resistance
答案: Higher on-state resistance
4、 Which of the following descriptions does not belong to the advantages of Power Module?
A:Reducing the volume of the device, reducing the cost and improving the reliability
B:Reducing the line inductance greatly for high frequency circuits
C:Improving insulation and heat dissipation
D:Changing the electrical structure
答案: Changing the electrical structure
5、 Which of the following descriptions does not belong to the characteristics of IGBT?
A: High switching speed and low switching loss compared with thyristor
B:The safe working area of Power MOSFET is larger than that of GTR, and it is capable of withstanding strike of impulse current
C: The driving power needed is larger than thyristor
D: Low on-state voltage drop
答案: The driving power needed is larger than thyristor
AC-DC conversion (Rectifier) Chapter 2 Test
1、 Which description is not ture for ordinary Thyristor?
A:Inside is a double transistor model of PNPN four layer semiconductor structure
B:When conducting, it should be saturation conduction, and there is only a small leakage current when blocking
C:Current is Injected into the gate when it is turned on and extracted from the gate when it is turned off
D:There are three link ends, anode pole, cathode pole and gate pole
答案: Current is Injected into the gate when it is turned on and extracted from the gate when it is turned off
2、 Which description is ture in normal operation characteristics of Thyristor?
A:Due to the load inductance, thyristor may flow through the reverse anode current
B:As long as the gate has a trigger current, the thyristor can be turned on
C:Once the thyristor is turned on, the gate loses its control function
D:In order to turn off the thyristor conducting, the anode current flowing through the thyristor should be reduced below the holding current
答案: Once the thyristor is turned on, the gate loses its control function
3、 The RMS value of the secondary side voltage of the transformer is U2. The single-phase bridge controlled rectifier supplies power for resistive load. The maximum forward voltage and reverse voltage that the thyristor can withstand are respectively ( )
A:
B:
C:
D:
答案:
4、 When the single-phase bridge controlled rectifier supplies power for large inductive load, its conduction angle q is ( )
A:a
B:90°
C:180°-a
D:180°
答案: 180°
5、 As shown in the figure, the single-phase bridge controlled rectifier is loaded with a large inductance. The thyristor trigger phase range is ( )
A:a
B:90°
C:180°-a
D:180°
答案: 90°
6、 As shown in the figure, the inductance of single-phase bridge controlled rectifier circuit is large enough, U2=200V，a=60°, the average rectifier voltage is ( )
A:127V
B:90V
C:180V
D:200V
答案: 90V
7、 In the commutation process of three-phase half wave controlled rectifier, the incorrect description of natural commutation point is ( )
A: If the thyristor is replaced by diode, the time of commutation
B:The earliest time when thyristor can trigger conduction
C: Intersection time of phase voltage
D: Intersection time of line voltage
答案: Intersection time of phase voltage
8、 When the load of three-phase half wave controlled rectifier is resistance, the maximum reverse voltage and maximum forward voltage of thyristor are respectively ( )
A:
B:
C:
D:
答案:
9、 When the three-phase bridge controlled rectifier is loaded with resistance, what is the correct description of rectifier output voltage ( )
A:The instantaneous value of output voltage may be negative
B:When a=90°, the value of output voltage is 0
C:The output voltage decreases with the increase of trigger angle
D:The output voltage may be part of the phase voltage
答案: The output voltage decreases with the increase of trigger angle
10、 As shown in the figure, in the three-phase full-bridge controlled rectifier circuit, the trigger phase difference of the two adjacent thyristors VT1 and VT3 in the common cathode group is ()
A:60°
B:90°
C:120°
D:180°
答案: 120°
11、 For the three-phase full-bridge controlled rectifier circuit driving an inductive load, the phase shift range of the trigger angle a is ()
A:60°
B:90°
C:120°
D:180°
答案: 90°
12、 For the three-phase full-bridge controlled rectifier circuit corresponding to the waveform shown in the figure below, the trigger angle a of the thyristors is ()
A:60°
B:90°
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