Solar Charge Controller

[sonar_abhi]

Hello All,

I have been designing a solar charge controller for 12 volt battery. The circuit is shown below. The parameters of the buck converter are as follows:

D1: Schotkey diode MBR1645
L: 8uH
Ci: 470uF
Co: 2000uF
Can anybody please validate the above design. The parameters are as follows:

Vin(min): 15V
Vout: 12 V
Iout: 15 A
Switching Frequency: 50kHz
Iripple: 30%
Vripple: 10%

The 1kHz PWM wave feeds the Dickson Charge Pump for driving the gate of the IRF44Z.

 

[treez]

I will have a look for you , but are you sure batt is 12v?..lead acid 12v is actually 13.8V.

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Also you do not have a feedback loop so that you can regulate the panel current to the maximum power current. Or regulate the panel voltage to the maximum power voltage , so to speak. You need that really

 

[sonar_abhi]

Hi Treez,

I am controlling the PWM with a micro controller that tracks the voltage of the battery via a voltage divider (not shown in the circuit diagram)

Also, the voltage and and current of the panel is monitored via a voltage divider and a current sensor (also not shown in the circuit diagram)

When the voltage of the battery is below 14 V, the PWM is at maximum duty cycle which charges the battery at Vmp of the panel. When the battery voltage rises upto 14 V, the duty cycle is reduced so as to keep the battery at trickle charge.

At the same time, a P&O algorithm monitors the panel power and if the panel is being loaded, it adjusts the duty cycle to keep the panel at Vmp.

 

[treez]

i will send soon the sim.
You have cout and cin the wrong way round.....ripple is worse for buck at input.
And anyway, you have a battery load....so that can be used is a big portion of your output capacitance.

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Anyway, attached is an ltspice simualtion of it, for you to check out. Also, the excel design document.

But you must put in your BJT based gate driver to see if all those bjts can switch quickly enough.
Also, you should put in your panel resistance so you can see how much vin falls as you "try" to pull the current that you want to out of it.