# How to build Bosst Converter ?

Discussion in 'The Projects Forum' started by Engjay, Mar 8, 2008.

1. ### Engjay Thread Starter Member

Mar 7, 2008
14
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hi everyone
i need to build up a boost converter
with input voltage 12v dc and output voltage 180v dc
and around 7 amp output current
is that possible with 12 v dc input or we need more voltage in?
itswill be use for a dc motor with input voltage out to 180vdc maximum
what kind of chip i need ?
i need the schematic circuit with it vallues?
plez i need your helps

2. ### hgmjr Retired Moderator

Jan 28, 2005
9,029
218
You are taking on quite a challenge since the output power of you supply will be 7*180 or 1260 Watts. Even with a highly efficient boost converter you will need to input 1.5 Kilowatts.

What are you powering with this supply?

hgmjr

3. ### Engjay Thread Starter Member

Mar 7, 2008
14
0
So What kind of Converter iam going to Use
i need 180v with 7 amp current
i need the circuit
Can you help me to build up the circuit ????
i can use more input voltage max to 36vdc max (3 battries )

i need it for the dc motor of course iam going to Use A Voltage controller
and (potentio meter )

4. ### hgmjr Retired Moderator

Jan 28, 2005
9,029
218
1500/12 equates to 125 Amps at the input of your supply. That is a hefty amount of current.

I am not familiar with any components that can switch that amount of current.

hgmjr

5. ### nanovate Distinguished Member

May 7, 2007
665
1
One bought from a professional power supply designer. All joking aside... Like hgmjr mentioned you are tallking about 1500 Watts assuming you have an 85% efficient converter-- which is 'really' an assumption for a fivefold high current boost. This is irregardless of whether you are using 12V or 36V input. Even with 36V input you are still looking at >35A input current. You are going to have to have monster sized components.

Maybe after you tells us the application someone might have a solution -- paralleling or multi-phase etc..

6. ### Engjay Thread Starter Member

Mar 7, 2008
14
0
So What should I do
Do You have any opinion for my Project
Iam Going To Buld Up an electric car
I got the dc motor with 180v max
and series 3000 and 1.5hp
the problem that i have
i dunno how to get 180v
and how Can i move the car
Where can i find a dc motor controller since the tradmill controller is useless becuse it take the ac part and i need dc
can you give me suggetions

Jan 18, 2008
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8. ### S_lannan Active Member

Jun 20, 2007
247
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although the figures match up i doubt that inverter is good for driving motors, most of those inverters strictly say not to use motors with them.

May 16, 2005
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10. ### scubasteve_911 Senior Member

Dec 27, 2007
1,202
1
For that kind of voltage increase, you will definitely need to use a flyback-boost typology. I have designed a 1KW boost converter for a car amplifier, I will try to find a schematic around.

You must come up with something slick to handle the 125A you will encounter. Probably looking at copper bus-bars of some sort. You can find MOSFETs that can handle that kind of current, but you are better off using paralleled FETs. These larger FETs will require a decent gate driver, probably in the order of 4 or more amperes sink/source. You do not want to be operating in the linear region for long with that sort of current, it will fry the FETs in no time.

I would pick up a good book in transformer design. You will probably end up with many parallel strands of an easy to wind magnet wire gauge for the primary.

Good luck

Steve

11. ### Engjay Thread Starter Member

Mar 7, 2008
14
0
our instructor
dont want us to use inverter
he want us to use buck -boost converter (dc-dc) at least 4 battries
48 vdc input to 180 vdc with 7 amp current output
where can i find a good dc motor controller
do you have a good sites
help me for this

12. ### jpanhalt Expert

Jan 18, 2008
7,270
1,638
As has already been pointed out, a buck-boost converter for that current will not be easy. Ask your instructor for some hints. John

13. ### Engjay Thread Starter Member

Mar 7, 2008
14
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Can you Give ME a good prove its will not work So i can tell our instructor it will not be easy so we can use inverter instead
i will be greatful for u guys

14. ### jpanhalt Expert

Jan 18, 2008
7,270
1,638
The manual for that particular inverter does not include a restriction against motors. In fact, it says power tools can be used.

However, that is not really the point. The motor being used by the OP is a brushed DC motor that comes with its own rectifier and controller. Thus, even though the sinewave quality from a cheap inverter may be poor, it's going to be converted back to DC.

The OP now reports that they are required to design and build a buck-boost converter that will produce approximately 2 kW at 180 VDC from 12-V storage batteries. That apparently has to be done before they can get on with the meat of the project, which seems to have somethig to do with robotics. Frankly, I think that is a bit ambitious for a one-year school project, and there seems to be a need to clearly define the scope and goal of the project. John

15. ### jpanhalt Expert

Jan 18, 2008
7,270
1,638
Go here and enter your specifications: Vin=12-14 V; Vout=180 V; Iout=10 A. Linear will respond that it can't help you. Of course, that doesn't prove it won't work...logically that is simply not possible to prove. A little searching, though, will show you it will not be easy with that topology.

http://www.linear.com/pc/viewCategory.jsp?navId=H0,C1,C1003,C1042&gclid=COnbra-fgJICFSGWGgodBi6T9A

John

Jan 1, 2008
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17. ### scubasteve_911 Senior Member

Dec 27, 2007
1,202
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aaroni,

I don't think that is what he is after. I have taken a look at the OSMC in the past, it seems that they just build a fancy h-bridge controller. The OP seeks a boost converter for use as a motor driver.

As for a reason why you shouldn't use a standard boost converter. You will need to operate the converter at a ~93.5% duty cycle. Extreme duty cycles impose inefficiently small off-times or low switching frequencies. Lower switching frequency causes higher ripple and requires larger magnetics.

Steve