Reg:Switching Frequency for DC-DC converter

[sakthivel.eee]

am converter dc to dc

Dear All,
THis is sakthivel from Varroc Enginnering. I am working as Engineer with R&D.

I want to design non-inverting buck-boost dc-dc converter. I am new to the dc-dc converter design.The spec is below.

Buck
Input voltage:48V
Output voltage:10Volts, 45amps

Boost
input voltage:10v
Output Voltage:48volts, 45amps

My question is what will be approximate switching fequency for pratical values of inductor and capacitor for this higher rating? ( I know that As switching frequency increases, inductor size decreases. switching loss increases)

I tryed to calculate the inductance value for 20KHZ as switching frequency. I got around 400uH. But i come to know that 400uH@45amps is diffcult to get in the market. IS it so? If it is, How much inductance value we will get for 45amps? IS 20KHZ is too low switching frequency for dc-dc converter? Generally for higher rating of DC-DC Conveter(45 amps 48 volts) what will be the switching frequency practically used?

Thnaks in advance

Thanks & Regards,
S.Sakthivel

 

[pauloynski]

dc converter frequency

The buck output power is 450W and the boost output power is 2160W. Is that right?

 

[sakthivel.eee]

dc converter frequencies

No..these all r approximate specification. i want to know only switching frequency.

 

[pauloynski]

switching frequency dc-dc converter

Using good quality ferrite cores you can go from 70 to 150kHz.

 

[newton brawn]

frequency efficiency dc-dc converter

well, if you can pass the complete schematic I will take a look.

regarding the transformer, the solution is you wid yourself. No doubt.

newton.b@live.com

Added after 3 minutes:

regarding the transformer, the solution is you WIND the transformer yourself. No doubt.

 

[sakthivel.eee]

what is switching frequency

HI
Actually My doubt is wheather 20KHZ is too low for 45Amps DC-DC Converter operation?
45Amps 500uF Inductors are available in the market? Is it optimestic to use it in DC-DC Converter?What will be size of the inductor

 

[doraemon]

switching frequency

Hello!

In many DCDC chips, the switching frequency is a few hundreds of kHz.
So I would guess that 20 k is not enough.

You said the drawback of high frequency is loss of efficiency. Indeed,
the more you have transient states of components, the more the consumption.
But on the other hand, high frequency allows you to make a simple coils with a
few loops of thick copper. As the efficiency also depends on the coil's resistance,
then if you will have a decent efficiency. Check also the FET's junction capacitance.


Dora.

 

[sakthivel.eee]

switching frequency of dc-dc converter

HI,
IS 500uH@45Amps practical value?Is it available in the market or is it so high value for DC-DC COnverter application?

Thanks in advance,

Thanks & Regards,
Sakthivel.S

 

[itaig]

low frequency to dc converter

With the currents involved and if efficiency is important, I would look at poly-phase regulators and synchronous rectifier controllers. These allow to build converters running upto and beyond 1MHz and achieve efficiencies of 98% or more.

The benefit of using poly-phase is the load is shared allowing the use of smaller and faster switching devices and decreasing losses in the inductor.

With a boost regulator, the peak inductor current is usually a lot higher than the load current so you have to watch out for core saturation.