GATE EE
Power Electronics
Choppers and Commutation Techniques
Previous Years Questions

## Marks 1

The steady state current flowing through the inductor of a DC-DC buck boost converter is given in the figure below. If the peak-to-peak ripple in the ...
A buck converter, as shown in Figure $$(a)$$ below, is working in steady state. The output voltage and the inductor current can be assumed to be rippl...
In the following chopper, the duty ratio of switch $$S$$ is $$0.4.$$ If the inductor and capacitor are sufficiently large to ensure continuous inducto...
A step-up chopper is used to feed a load at $$400$$ $$V$$ $$dc$$ from a $$250$$ $$V$$ $$dc$$ source. The inductor current is continuous. If the ‘off’ ...
The power electronic converter shown in the figure has a single-pole double-throw switch. The pole $$P$$ of the switch is connected alternately to thr...
A step down chopper is operated in the continuous conduction mode in steady state with a constant duty ratio $$D.$$ If $${V_0}$$ is the magnitude of t...
In a thyristor $$dc$$ chopper which type of commutation results in best performance?
Consider the chopper circuit of figure. The chopper operates at $$400$$ $$Hz$$ and $$50$$% duty cycle. The load current remains almost ripple free at...
A $$dc$$ to $$dc$$ transistor chopper supplied from a fixed voltage $$dc$$ source feeds a fixed resistive-inductive load and a free-wheeling diode. Th...
Match the following List $$-$$ $${\rm I}$$ $$A.$$ Commutation $$B.$$ $$V$$ $$-$$ Curves $$C.$$ Free wheeling diode $$D.$$ Overlap List $$-$$ $${\rm II... A chopper operating at a fixed frequency is feeding an$$R$$-$$L$$load. As the duty ratio of the chopper is increased from$$25\% $$to$$75\% $$, th... ## Marks 2 The figure shows two buck converters connected in parallel. The common input dc voltage for the converters has a value of 100 V. The converters have i... A dc to dc converter shown in the figure is charging a battery bank, B2 whose voltage is constant at 150 V. B1 is another battery bank whose voltage i... In the circuit shown all elements are ideal and the switch$$S$$is operated at$$10kHz$$and$$60$$% duty ratio. The capacitor is large enough s... The input voltage$${V_{DC}}$$of the buck-boost converter shown below varies from$$32V$$to$$72V.$$Assume that all components are ideal,... For the switching converter shown in the following figure, assume steady-state operation. Also assume that the components are ideal, the inductor curr... A buck converter feeding a variable resistive load is shown in the figure. The switching frequency of the switch$$S$$is$$100kHz$$and the duty... The circuit shown is meant to supply a resistive load$${R_L}$$from two separate$$DC$$voltage sources. The switches$$S1$$and$$S2$$are controlle... A self commutating switch$$SW,$$operated at duty cycle$$\delta $$is used to control the load voltage as shown in the figure Under steady state ... Figure (i) shows the circuit diagram of a chopper. The switch$$S$$in the circuit in figure (i) is switched such that the voltage$${V_D}$$across th... In the figure shown below, the chopper feeds a resistive load from a battery source.$$MOSFETQ$$is switched at$$250kHz,$$with a duty rati... In the figure shown below, the chopper feeds a resistive load from a battery source.$$MOSFETQ$$is switched at$$250kHz,$$with a duty rati... In the circuit shown, an ideal switch$$S$$is operated at$$100kHz$$with a duty ratio of$$50%$$. Given that$$\Delta {i_c}$$is$$1.6A$$... A voltage commutated chopper circuit, operated at$$500Hz,$$is shown below. If the maximum value of load current is$$10A,$$then the maximum current... The L-C circuit shown in the figure has an inductance$$L=1mH$$and a capacitance$$C = 10\mu F.$$The initial current through the inductor is zero, w... The L-C circuit shown in the figure has an inductance$$L=1mH$$and a capacitance$$C = 10\mu F.$$The$$L$$-$$C$$circuit$$Q.13$$is used to commuta... In the chopper circuit shown, the main thyristor$$\left( {{T_M}} \right)$$is operated at a duty ratio of$$0.8$$which is much larger than the commu... In the circuit shown in the figure, the switch is operated at a duty cycle of$$0.5.$$A large capacitor current is connected across the load. The ind... The circuit in the figure is current commutated$$dc-dc$$chopper where,$$T{h_M}$$is the main$$SCR$$and$$T{h_AUX}$$is the auxiliary$$...
A voltage commutated chopper operating at $$1$$ $$kHz$$ is used to control the speed of $$dc$$ motor as shown in figure. The load current is assumed t...
A voltage commutated chopper operating at $$1$$ $$kHz$$ is used to control the speed of $$dc$$ motor as shown in figure. The load current is assumed t...
A voltage commutation circuit is shown in figure. If the turn off time of the $$SCR$$$$s$$ is $$50$$ $$\mu \sec$$ and as safety margin of $$2$$ is c...
The given figure shows a step $$-$$ down chopper switched at $$1$$ $$KHz$$ with a duty ratio $$D = 0.5.$$ The peak - peak ripple in the load current i...
Figure shows a chopper. The device $${S_1}$$ is the main switching device. $${S_2}$$ is the auxiliary commutation device. $${S_1}$$ is rated for $$400... Figure shows a chopper operating from a$$100Vdc$$input. The duty ratio of the main switch$$S$$is$$0.8.$$The load is sufficiently induc... A chopper is employed to charge a battery as shown in figure. The charging current is$$5A$$. The duty ratio is$$0.2.$$The chopper output voltage is... In the chopper circuit shown in fig the input$$dc$$voltage has a constant value$${{V_s}}$$. the output voltage$${{V_0}}$$is assumed ripple free. ... A step down chopper operates from a$$dc$$voltage source$${V_s}$$feeds a$$dc$$motor armature with a back$$e.m.f\,\,{E_b}.$$From oscillosco... ## Marks 5 In fig, the ideal switch$$S$$is switched on and off with a switching frequency$$f = 10 kHz.$$The switching time period is$$\,T = {t_{ON}} + t{}_{...
A voltage commutated thyristor chopper circuit is shown in fig. The chopper is operated at $$500$$ $$Hz$$ with $$50\%$$ duty ratio. The load takes a ...
A $$dc$$ motor with armature resistance $${R_a}$$ is fed from a step down chopper in the continuous mode, and operates at some known speed and known e...
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