Power Electronics

Consider the circuit shown in Figure (a). A gate pulse Vg is applied between time instants t0 and t1. After t1, during the MOSFET turn OFF process, it experiences a voltage oversho...

Consider the single-phase voltage source inverter circuit feeding an inductive load (L). Assume that the power MOSFET switches are ideal. S1 and S2 are switched on during the first...

Consider the boost converter circuit shown. Assume that the semiconductor devices are ideal. In steady state, the inductor current rises linearly from 0 A to 6 A in the first 10 µs...

The 3-phase modulating waveforms ($v_a(t)$, $v_b(t)$ and $v_c(t)$), used in sinusoidal PWM in a Voltage Source Inverter (VSI) are $v_a(t) = 0.8 \sin (\omega t)$ V $v_b(t) = 0.8 \si...

An ideal sinusoidal voltage source $v(t) = 230\sqrt{2} \sin(2\pi \times 50t)$ V feeds an ideal inductor L through an ideal SCR with firing angle $\alpha = 0^{\circ}$. If $L = 100$...

If the following switching devices have similar power ratings, which one of them is the fastest?

A single-phase triac based AC voltage controller feeds a series RL load. The input AC supply is 230 V, 50 Hz. The values of R and L are 10 Ω and 18.37 mH, respectively. The minimum...

A forced commutated thyristorized step-down chopper is shown in the figure. Neglect the ON-state drop across the power devices. Assume that the capacitor is initially charged to 50...

A single-phase half-controlled bridge converter supplies an inductive load with ripple free load current. The triggering angle of the converter is 60°. The ratio of the rms value o...

A single-phase full bridge voltage source inverter (VSI) feeds a purely inductive load. The inverter output voltage is a square wave in 180° conduction mode. The fundamental freque...

In the DC-DC converter shown in the figure, the current through the inductor is continuous. The switching frequency is 500 Hz. The voltage ($V_o$) across the load is assumed to be...

The chopper circuit shown in figure (i) feeds power to a 5 A DC constant current source. The switching frequency of the chopper is 100 kHz. All the components can be assumed to be...

A semiconductor switch needs to block voltage V of only one polarity (V > 0) during OFF state as shown in figure (i) and carry current in both directions during ON state as shown i...

The circuit shown in the figure has reached steady state with thyristor 'T' in OFF condition. Assume that the latching and holding currents of the thyristor are zero. The thyristor...

A six-pulse thyristor bridge rectifier is connected to a balanced three-phase, 50 Hz AC source. Assuming that the DC output current of the rectifier is constant, the lowest harmoni...

The output voltage of a single-phase full bridge voltage source inverter is controlled by unipolar PWM with one pulse per half cycle. For the fundamental rms component of output vo...

A DC-DC buck converter operates in continuous conduction mode. It has 48 V input voltage, and it feeds a resistive load of 24 \Omega. The switching frequency of the converter is 25...

In a DC-DC boost converter, the duty ratio is controlled to regulate the output voltage at 48 V. The input DC voltage is 24 V. The output power is 120 W. The switching frequency is...

A fully-controlled three-phase bridge converter is working from a 415 V, 50 Hz AC supply. It is supplying constant current of 100 A at 400 V to a DC load. Assume large inductive sm...

A single-phase fully-controlled thyristor converter is used to obtain an average voltage of 180 V with 10 A constant current to feed a DC load. It is fed from single-phase AC suppl...

A phase-controlled, single-phase, full-bridge converter is supplying a highly inductive DC load. The converter is fed from a 230 V, 50 Hz, AC source. The fundamental frequency in H...

The figure below shows the circuit diagram of a controlled rectifier supplied from a 230 V, 50 Hz, 1-phase voltage source and a 10:1 ideal transformer. Assume that all devices are...

The input voltage V_DC of the buck-boost converter shown below varies from 32 V to 72 V. Assume that all components are ideal, inductor current is continuous, and output voltage is...

A phase controlled single phase rectifier, supplied by an AC source, feeds power to an R-L-E load as shown in the figure. The rectifier output voltage has an average value given by...

In the circuit shown all elements are ideal and the switch S is operated at 10 kHz and 60% duty ratio. The capacitor is large enough so that the ripple across it is negligible and...

A phase-controlled, single-phase, full-bridge converter is fed from a $$230$$ $$V,$$ $$50$$ $$Hz,$$ $$AC$$ source. The fundamental frequency in $$Hz$$ of the voltage ripple on the...

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’ time of the switch is $$20\,\,...

A three phase fully controlled bridge converter is feeding a load drawing a constant and ripple free load current of $$10$$ $$A$$ at a firing angle of $${30^ \circ }.$$ The approxi...

A single $$-$$ phase, $$230$$ $$V$$, $$50$$ $$Hz$$ $$ac$$ mains fed step down transformer $$(4:1)$$ is supplying power to a half $$-$$ wave uncontrolled $$ac$$ $$-$$ $$dc$$ convert...

A $$3$$-phsae, fully controlled, converter is feeding power into a $$d.c.$$ load at a constant current of $$150A.$$ The $$r.m.s$$ current through each thyristor of the converter is

When the firing angle $$\alpha $$ of a single phase, fully controlled rectifier feeding constant $$d.c.$$ current into a load is $${30^ \circ }$$ , the displacement power factor of...

The uncontrolled electronic switch employed in power electronic converters is

A line - commutated inverter changes $$dc$$ voltage to $$ac$$ voltage

Match the following List $$-$$ $${\rm I}$$ $$A.$$ Commutation $$B.$$ $$V$$ $$-$$ Curves $$C.$$ Free wheeling diode $$D.$$ Overlap List $$-$$ $${\rm II}$$ $$P.$$ Resistive load $$Q....