Battery charging - should I stop PWM when measuring voltage?

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hne573

Joined: 26 Feb 2009
Posts: 16
Helped: 4

14 Jul 2009 12:57 Battery Charging - Help?

Hi,
I want to make a battery charger LiIon with a micro controller.
I study about Li-Ion battery, charging methods and ...
LiIon should be charge with Constant Current/Constant Voltage method.
So we should be able to control current and voltage of charger.
So I use PWM for controlling these signals.
PWM On/Off Fets for charging with determined current and voltage
and with ADC we measured the voltage and current.
After reading the current and voltage, the duty cycle must be changed
if needed(change with PWM).
Now I want know, Should be stop the PWM when I want to measure voltage
and current?If yes, why? or if no, why?
please help me.

bobcat1

Joined: 10 Jul 2002
Posts: 1118
Helped: 48

14 Jul 2009 17:36 Re: Battery Charging - Help?

Hi
Atmel,TI,Freescale,Microchip have application note with software & hardware for li-ion battery charger where you can learn more

All the best

Bobi

chanchal.chauhan

Joined: 23 Apr 2009
Posts: 37
Helped: 2

16 Jul 2009 11:54 Re: Battery Charging - Help?

Dear hne573,

Here is your solution's

Should be stop the PWM when I want to measure voltage
and current?If yes, why? or if no, why?

If you want to charge the battery, you have to give continuous pulse & monitor the voltage & current continuously.Both are co-related without pulse voltage & current won't come & without voltage & current you can't charge the battery.So both is mandatory.So you shouldn't stop PWM pulse.

So your firmware flow will be like this :-
1. First Acquire the sensing voltage.
2. Acquire the sensing current.
3. Do necessary action to control voltage & current by using PWM.

By the way are you using any control techniques?
Please let me know

Regards
Chanchal