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WorksheetsPower Electronics Quiz 2
Total questions: 20
Worksheet time: 7mins
In a single-phase half-wave fully controlled converter, the SCR conducts for:
180° of the input cycle
Less than 180° of the input cycle
360° of the input cycle
More than 180° of the input cycle
The firing angle (α) in a controlled converter is measured from:
The zero crossing of the input voltage
The peak of the input voltage
The zero crossing of the load current
The natural commutation point
For a single-phase full-wave fully controlled converter with R load, the number of SCRs required is:
1
2
4
6
The average output voltage of a single-phase half-wave controlled converter with firing angle α is:
(Vm/π)(1 + cos α)
(Vm/π)(1 - cos α)
(Vm/2π)(1 + cos α)
(Vm/2π)(1 - cos α)
The conduction angle of each SCR in a three-phase half-wave controlled converter is:
60°
120°
180°
360°
For an RL load in a controlled converter, the current:
Can become discontinuous
Is always continuous
Depends on the L/R ratio
Is independent of firing angle
The freewheeling diode in a controlled converter is used to:
Increase the output voltage
Provide a path for inductive load current
Reduce the firing angle
Increase the power factor
In an RLE load, the back EMF (E) acts to:
Increase the average output voltage
Decrease the average output voltage
Oppose the applied voltage
Support the applied voltage
Source inductance in a controlled converter causes:
Commutation overlap
Reduced output voltage
Increased ripple factor
All of the above
The overlap angle (μ) in a converter is caused by:
Load inductance
Source inductance
Firing angle delay
SCR turn-on time
In a dual converter configuration:
Both converters operate simultaneously
Only one converter operates at a time
Converters are connected in parallel
Converters share the same SCRs
A light dimmer circuit typically uses:
Single-phase half-wave controlled converter
Single-phase full-wave controlled converter
Three-phase controlled converter
Uncontrolled rectifier
In solar PV systems, controlled converters are used for:
MPPT control
Grid synchronization
Power conditioning
All of the above
The ripple factor of a three-phase full-wave controlled converter is:
Higher than single-phase
Lower than single-phase
Same as single-phase
Independent of phase number
The natural commutation in SCRs occurs when:
Current becomes zero
Voltage becomes zero
Gate signal is removed
Load is disconnected
The extinction angle (β) is related to firing angle (α) by:
β = 180° - α
β = 180° + α
β = α
β = 90° - α
The pulse number in a three-phase full-wave converter is:
3
6
9
12
A single-phase full-wave controlled converter feeding an RL load operates with α = 60°. If the source inductance causes an overlap of 15°, what is the actual conduction period of each SCR?
105°
120°
135°
150°
To design a dual converter system for a 10 kW DC motor drive, which configuration would provide the best performance considering both motoring and regenerative braking operations?
Two single-phase half-wave converters
Two single-phase full-wave converters in anti-parallel
Two three-phase half-wave converters
Single three-phase full-wave converter with reversing switch
In a solar PV grid-tied system, a controlled converter shows reduced efficiency at light loading conditions. Which factor is MOST critical to evaluate for improving performance?
Switching frequency optimization
Firing angle control strategy
Power factor correction
Harmonic filtering
