b Explain unipolar switching scheme operation for a PWR inverter 8M 2 of 2 R13

B explain unipolar switching scheme operation for a

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b) Explain unipolar switching scheme operation for a PWR inverter? R13 SET - 3
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|''|'''||''||'''|||| Code No: RT31025 III B. Tech I Semester Regular/Supplementary Examinations, October- 2016 POWER ELECTRONICS (Electrical and Electronics Engineering) Time: 3 hours Max. Marks: 70 Note: 1. Question Paper consists of two parts ( Part-A and Part-B) 2. Answering the question in Part-A is compulsory 3. Answer any THREE Questions from Part-B ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PART –A 1 a) Describe the significance of di/dt and dv/dt in SCRs. [3M] b) Explain the principle of line commutation. [4M] c) Explain the effect of battery load on the performance of single phase fully controlled bridge converter. [3M] d) What are the advantages of 6-pulse converter over 2-pulse converter? [4M] e) What are the control strategies for the regulation of output voltage in ac voltage controller? [3M] f) Explain the operation of single-phase inverter. [4M] PART -B2 a) For a single phase half wave rectifier feeding a resistive load R, find the values of rectifier efficiency, form factor, voltage ripple factor, transformer utilization factor and crest factor when 00=α[10M] b) Explain briefly different turn on methods used for SCR. [6M] 3 a) Define the term power factor. Derive its expression for single phase voltage controller feeding a resistive load circuit. [7M] b) A resistive load of 10 is connected through a half-wave SCR circuits to 220v, 50Hz, single- phase source. Calculate the power delivered to load for a firing angle of 600.Find also the value of input power factor. [9M] 4 A Single phase full converter delivers a constant load current Io. Express its source current in Fourier series and derive expressions for the following performance parameters. (i) Displacement factor (ii) Power factor (iii) THD (iv) Current distortion factor [16M] 5 a) Explain the operation of a three phase dual converter in the non circulating current mode with the help of relevant waveforms. Derive the expression for the average output voltage. [10M] b) A three phase fully controlled bridge converter is fed from a 3-phase 400 V, 50Hz mains. For firing angle of 600, output current is 25 A and output voltage is 250 V. Calculate the load resistance, source inductance and angle of overlap. [6M] . 1 of 2 R13 SET - 4
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Code No: RT31025 6 a) Discuss the working of a single phase bridge type cyclo converter with RL load for continuous conduction operation with relevant output waveforms and circuit diagram for f0= (1/4) fs. b) Explain the principle of operation of a Back- Boost converter. [8M] 7 a) Explain the working of a single-phase half bridge inverter. Discuss how the output power in single-phase full bridge inverter becomes four times the power handled by a single phase half-bridge inverter. [8M] b) Describe briefly and compare the various methods employed for the control of output voltage of inverters. R13 SET - 4
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