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### Highlights from Buck/Boost Converter

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# Buck/Boost Converter

A DC DC Converter capable of buck/ Boost input voltage

File Information
Description

Below 50 % duty cycle it steps down the DC Voltages and from 50 -99% of duty cycle it steps up the input voltage

Required Products SimPowerSystems
MATLAB release MATLAB 7.7 (R2008b)
07 Jan 2014
25 Dec 2013
23 Jun 2013

thanks

09 Feb 2012

i made my buck boost circuit but i am having problem on what values for L and C i have to put in order to get the correct out put graphs

thankx

03 Jun 2010

Dear wassay, hope that you have the answer of the question

03 Jun 2010

I am designing MPPT controller for solar pv panels, kindly i wanted to ask you about the operation of Cuk converter the out put of cuk is also negative. so is there any method that the duty cycle of dc-dc converters automatically changes with the time? like i have seen in some reference papers that they do some feed back to the controller to change the duty cycle with time.. plz need your help regarding this .. i would really appreciate ur effort.

29 May 2010

there are several books on this topic. generally this circuit is not used for BUCK/BOOST operation. designers use regular topologies of buck and boost for these specific tasks. The answer to this question is very well discussed in the book i mentioned above.

29 May 2010

Sir,
I have a small query reg Buck Boost converter,

1. If mode of operation is Buck , let i/p vol is 200 V , my doubt is what the minimum voltage we can get , and how this will be decided in practical ckts as well as simulation ckt

In similarly

2. If mode of operations is Boost , let Input vol 24 V , then what max output voltage can be obtained at o/p , what factors affect this range of o/p voltage

Thank you sir

29 May 2010

well if you need a positive voltage then add an other BUCK/BOOST circuit with 52% duty cycle (Since at 50 % due to losses in circuit elements output will be slightly less then input).
Secondly the circuit elements needs redesigning if you disturb the input voltages to a very large extent. Theoretically it must give us infinite output voltage at 100 % duty cycle but it never happens because of the fact that practically there are always losses in circuit elements

29 May 2010
29 May 2010

Thank you for the realy reply

and Let me correct .........

What changes to be done in the circuit if i want +ve o/p voltage ...

I simulated ur ckt for boost operation of 24 V input to 200 V output by setting duty cycle 89.23% (calculated from Vo/p / Vin = D/(1-D)) ...........

I got the output of -157 V , where i were wrong ......Plz help me.

Thank You

29 May 2010

@manjunath: This type of DC DC converter is also known as polarity inverting converter(For more information on DC DC Converter please refer to Switching power supply design by Abraham I pressman). The output is always inverted .So there is nothing wrong with this circuit.

29 May 2010

Good file.........
i simulated it but , it is giving -ve output voltages in both buck and boost modes , plz check it once