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Power Electronics Interview Questions and Answers: Set­2

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· December 25, 2013

Power Electronics Technical Interview Questions and Answers: Some of the

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Power Electronics Interview Questions and Answers: Set­2

Power electronics technical interview questions with answers are given in this post. These questions

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Linear Power Supply Design (4)

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Power Electronics Basics (7)

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were asked in various power electronics company interviews to

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some of our

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friends. We collected the questions from our friends and answer them in detail. We are confident that these Power

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Electronics Technical Interview Questions will be helpful for you, while preparing for interviews…

[Q-1]  Draw the http://www.completepowerelectronics.com/power­electronics­technical­interview­questions/

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Power Electronics Interview Questions and Answers: Set­2

buck topology? In most of the power electronics interview questions, you are going to face this basic question. Not only buck converter, the interviewer may ask you to draw other fundamental topologies too…

So you should be familiar with other basic topologies like Flyback, Boost , Buck-boost…. [Q-2]  Which is the good choice among the 2 options mentioned below to get the 12V as an output? why? Option I: Input voltage = 48V, http://www.completepowerelectronics.com/power­electronics­technical­interview­questions/

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Power Electronics Interview Questions and Answers: Set­2

Option II: Input voltage = 24V Answer: We know that Duty cycle D = Vout / VInput For case I D = 12/48 = 0.25 For case II D = 12/24 = 0.5 So for case II, the duty cycle is more than case I. It means device is turned ON more time in the second case. while deg SMPS we have to consider the principle mentioned in Q3. [Q-3] What is effect of having more duty cycle and less duty cycle? ( continuation of above question) If the duty cycle http://www.completepowerelectronics.com/power­electronics­technical­interview­questions/

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Power Electronics Interview Questions and Answers: Set­2

D is greater than 0.5, the core would not be completely demagnetized at the end of the off-period, and a DC magnetization of the core would build up, resulting in core saturation. Relate this answer the previous question…. [Q-4] To design the buck converter, what are basic & essential information (parameters) we need to get from the Customer? We need the following inputs from the customer, Output Voltage VOUT Input Voltage VIN http://www.completepowerelectronics.com/power­electronics­technical­interview­questions/

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Power Electronics Interview Questions and Answers: Set­2

Output Current (load current) IOUT Maximum Ripple voltage allowed at the output side Efficiency of the converter [Q-5] How to select the inductor for the buck converter? Once the topology is finalized in the process of power supply design, the next step is selecting the Inductor. We know the following basic equation Voltage across Inductor VL = L di/dt Rewriting the above equation as follows L = VL.dt/di VL = Maximum voltage appears across the Inductor http://www.completepowerelectronics.com/power­electronics­technical­interview­questions/

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Power Electronics Interview Questions and Answers: Set­2

dt= The time during which the maximum voltage appears across the inductor di = Ripple current VL The maximum voltage appears across the inductor when the power switch is turned on. During that time the voltage will be VL = VOUT – VIN dt = The time during which the maximum voltage appears across the inductor = D/FS = Duty cycle/Switching frequency di = Ripple current = Generally it is assumed in between 10% to 30% of the load http://www.completepowerelectronics.com/power­electronics­technical­interview­questions/

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Power Electronics Interview Questions and Answers: Set­2

current By knowing all these values we can get the required inductor value for the buck converter. [Q-6] What are the various parameters we have to consider, while selecting IGBT? In IGBT datasheet, we have to focus on following parameters Collector to emitter voltage VCES Collector Current IC Collector Dissipation PC Junction Temperature Tj [Q-6] For Selecting MOSFET, what are the major parameters we have to consider in http://www.completepowerelectronics.com/power­electronics­technical­interview­questions/

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the datasheet? In MOSFET datasheet, we have to focus on following parameters: Drain to Source Voltage VDSS On state Drain to Source Resistance RDS(ON) Reverse Recovery Current IRR Reverse Recovery Charge QRR Gate Charge QG Body Diode Characteristics ID at ambient temperature Channel power dissipation Channel temperature We believe that these power electronics technical interview questions might http://www.completepowerelectronics.com/power­electronics­technical­interview­questions/

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have stimulated your technical knowledge… If you have questions why don’t you share with our subscribers? Related Posts: Power Electronics Basic Interview Questions: Set-3 Power Electronics Interview Questions: Set-1

2 RESPONSES  Comments 2  Pingbacks 0 Prabhat 

February 11, 2015 at 5:56

am

Very good questions. Reply ajaz ahmed k 

April 28, 2015 at 6:32 am

thanks for giving good information Reply

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Power Electronics Interview Questions and Answers: Set­2

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