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WorksheetsPower Electronics Quiz 3
Total questions: 20
Worksheet time: 7mins
A step-down chopper produces an output voltage that is:
Always greater than input voltage
Always less than input voltage
Equal to input voltage
Independent of duty cycle
The duty cycle (D) of a chopper is defined as:
TON/T
TOFF/T
TON/TOFF
T/TON
In a Buck converter, the average output voltage is given by:
Vo = D × Vin
Vo = Vin/D
Vo = Vin/(1-D)
Vo = Vin × (1-D)
A Boost converter is used for:
Step-down operation only
Step-up operation only
Both step-up and step-down
Isolation purposes
The voltage gain of a Boost converter is:
D
1-D
1/D
1/(1-D)
In a Buck-Boost converter, the output voltage polarity is:
Same as input
Opposite to input
Always positive
Depends on duty cycle
The control strategy most commonly used in choppers is:
Voltage control
Current control
PWM control
Frequency control
Type B chopper allows:
Power flow from source to load only
Power flow from load to source only
Bidirectional power flow
No power flow
Type C chopper is a combination of:
Type A and Type B
Type A and Type D
Type B and Type D
Type D and Type E
The main switching element in a chopper circuit is typically:
Diode
Transistor
SCR
MOSFET or IGBT
The freewheeling diode in a Buck converter provides a path for:
Input current during OFF period
Output current during OFF period
Inductor current during OFF period
Capacitor current during ON period
Switched Mode Power Supply (SMPS) offers advantages like:
High efficiency
Small size
Light weight
All of the above
Resonant converters operate at:
Fixed frequency
Variable frequency near resonance
Very low frequency
DC conditions
The main advantage of resonant converters is:
High switching losses
Zero voltage switching (ZVS)
Complex control
High component stress
Voltage-to-Frequency (V/F) converters are used for:
Power conversion
Signal conditioning
Motor speed control
All of the above
The ripple in output voltage of a chopper can be reduced by:
Increasing switching frequency
Using larger output capacitor
Using output filter inductor
All of the above
Boundary condition between CCM and DCM occurs when:
Inductor current just touches zero
Output voltage becomes zero
Input current becomes zero
Duty cycle becomes 0.5
The efficiency of a well-designed chopper circuit is typically:
60-70%
70-80%
85-95%
Above 95%
A Buck converter operates with Vin = 24V, D = 0.4, f = 50kHz, L = 100μH, and R = 4Ω. Analyze whether the converter operates in CCM or DCM:
CCM, because inductance is large
DCM, because duty cycle is low
CCM, because Lmin = 40μH < 100μH
DCM, because switching frequency is high
For a battery-powered electric vehicle requiring both acceleration (step-down) and regenerative braking (step-up), which chopper configuration would be most suitable?
Buck converter with reverse diode
Boost converter with bidirectional switch
Buck-boost converter with isolation transformer
Type C chopper (Buck + Boost combination)
