Design Battery Charger using H-bridge Mosfet concept

[samson.bunty1986]

Hi,

Am planing to design a battery charger using H bridge mosfet configuration


Battery spec as follows:

Battery voltage ---24V
Battery capacity -- 45Ah

So the charging current should be 10% of battery capacity. am i correct??

So the charging current is 5A.

Am having some querys. What are the mosfets hve to be used?? Is it 2
N-channel & 2 P channel mosfets??
How to controll the current if the battery is getting charged??(I mean how
to reduce the current)

As we know mosfet is voltage controlled devices,but how they are
controlling current here??

How mosfets actually works in positive and negative cycles of AC??

Kindly support me ,am new to this design.
Do you have any reference designs??



---------------------------------------
Posted through http://www.Electronics-Related.com

[mike]

On 4/20/2013 5:52 AM, samson.bunty1986 wrote:
> Hi,
>
> Am planing to design a battery charger using H bridge mosfet configuration

> .

>
> Battery spec as follows:
>
> Battery voltage ---24V
> Battery capacity -- 45Ah
>
> So the charging current should be 10% of battery capacity. am i correct??
>
> So the charging current is 5A.
>
> Am having some querys. What are the mosfets hve to be used?? Is it 2

> N-channel& 2 P channel mosfets??

> How to controll the current if the battery is getting charged??(I mean how
> to reduce the current)
>
> As we know mosfet is voltage controlled devices,but how they are
> controlling current here??
>
> How mosfets actually works in positive and negative cycles of AC??
>
> Kindly support me ,am new to this design.
> Do you have any reference designs??
>
>
>
> ---------------------------------------
> Posted through http://www.Electronics-Related.com

What's the battery technology?
What is the vendor's charging recommendation?
What other design requirements have you not yet disclosed?

If it's lead acid, why not just get a golf-cart charger?
You can't possibly build one (with unit pricing at retail)
for less cost...given your level of experience.

[Rheilly Phoull]

On 20/04/13 20:52, samson.bunty1986 wrote:
> Hi,
>
> Am planing to design a battery charger using H bridge mosfet configuration
>

Why use H bridge when a single mosfet with PWM will do the job ?

[Tim Wescott]

On Sat, 20 Apr 2013 07:33:54 -0700, mike wrote:

> On 4/20/2013 5:52 AM, samson.bunty1986 wrote:
>> Hi,
>>
>> Am planing to design a battery charger using H bridge mosfet
>> configuration .

What powers your battery charger?

>> Battery spec as follows:
>>
>> Battery voltage ---24V Battery capacity -- 45Ah
>>
>> So the charging current should be 10% of battery capacity. am i
>> correct??

Almost certainly not, but maybe. What battery type?

>> So the charging current is 5A.
>>
>> Am having some querys. What are the mosfets hve to be used?? Is it 2
>> N-channel& 2 P channel mosfets??

It can be two of each, or four N-channels. If you're charging from a
direct-current source then you only need two MOSFETs.

>> How to controll the current if the battery is getting charged??(I mean
>> how to reduce the current)

You really, really, don't know enough to even start designing this.
Normally you'd build a switching supply. You'd monitor the battery
current and voltage, and control the charging current and/or voltage by
modulating the duty cycle of the switching.

>> As we know mosfet is voltage controlled devices,but how they are
>> controlling current here??

That depends on what you're doing. In a switching supply they are being
rapidly turned on and off. The duration they're on vs. the total cycle
time (the "duty cycle"), the supply voltage, and the load voltage all
determine current.

>> How mosfets actually works in positive and negative cycles of AC??

In general they don't. If you're building an off-line switcher you
generally rectify the incoming AC to DC, then use the resulting DC to
power your electronics.

>> Kindly support me ,am new to this design.
>> Do you have any reference designs??

From the sounds of things you really need to learn more about electronics
before you start trying to figure out a reference design.

The 2008 ARRL Handbook has a project for a 13.8V off-line switcher; many
of the principles are the same as for your battery charger (in fact,
there's a good chance that with the proper control electronics that
circuit could be used to charge 12V lead-acid batteries).

I would suggest that you get onto the various semiconductor web sites and
look for applications notes. "Off line power supply", "switching power
supply" and "power factor correction" are all search terms that may get
you useful applications notes.

>
> What's the battery technology?
> What is the vendor's charging recommendation?
> What other design requirements have you not yet disclosed?
>
> If it's lead acid, why not just get a golf-cart charger? You can't
> possibly build one (with unit pricing at retail)
> for less cost...given your level of experience.

If it's lead acid and you do build the charger, then you can't just go
constant current -- you need to do a constant current charge up to a
specific voltage (the nominal value of which escapes me at the moment, it
varies with temperature, and I'm not sure that it doesn't vary by
specific battery type).

--
Tim Wescott
Control system and signal processing consulting
www.wescottdesign.com

[Jim Thompson]

Charging a battery from a full-H bridge makes about as much sense as
using a full-H bridge for motor _speed_ control, when it only should
be used to change direction >:-}

...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

[Jamie]

Really?

I can think of a scenario..

Polarity auto sense and the ability to perform load testing between
the charge pulse to test the life of the cell/battery.

Btw, we have a charger at work that does that very thing, it has a H
bridge circuit. you can plop the battery on the holder any way you wish,
it auto senses polarity and knows which side of the bridge to charge it
on and uses the opposite side as a pulsed load test as it is being charged.

Jamie

[Michael A. Terrell]

So, it's fool proof because you only have fools to use it.

[Tim Wescott]

Hey! I resemble that remark!

--
My liberal friends think I'm a conservative kook.
My conservative friends think I'm a liberal kook.
Why am I not happy that they have found common ground?

Tim Wescott, Communications, Control, Circuits & Software
http://www.wescottdesign.com

[Jim Thompson]

On Thu, 25 Apr 2013 10:53:17 -0700, Fred Abse
<excret...@invalid.invalid> wrote:

>On Sat, 20 Apr 2013 17:21:48 -0700, Jim Thompson wrote:
>

>> Charging a battery from a full-H bridge makes about as much sense as using
>> a full-H bridge for motor _speed_ control, when it only should be used to
>> change direction >:-}
>

>Or controlled braking.

Yep.

[Jamie]

Fred Abse wrote:

> On Sat, 20 Apr 2013 17:21:48 -0700, Jim Thompson wrote:
>
>

>>Charging a battery from a full-H bridge makes about as much sense as using
>>a full-H bridge for motor _speed_ control, when it only should be used to
>>change direction >:-}
>
>

> Or controlled braking.
>
Guess no one has never heard of auto sensing polarity chargers and load
testing.

We have a charger at work that uses an H bridge, you can connect the
battery any way you wish, as long as it has at least .5 volt or more,
anything less, it assumes nothing connected and does not make an attempt
to select a polarity and turn on.

during a low state battery, the unit switches the bridge for a load
test to determine if the battery is accumulating useful energy, if not,
it'll give up and flash a bad battery LED>

Jamie