2 kW 40A MPPT solar charger based on STM

Greetings colleagues, my name is Johan and today I want to tell you about my project which is a 2kW MPPT solar charger with a maximum charging current of 40A

This charger was designed from the STM32F103C8 microcontroller since due to the complexity of the MPPT algorithm a good handheld processing speed with good precision ADC was needed, the power stage of this MPPT is designed from a synchronous source using mosfets common N channel as they are available anywhere in addition to their low cost and the great power they can handle.

The efficiency of this charger if a common source with a diode had been used was around 80%, while with the implementation of a synchronous source this would be around 97%, crazy :). At this point I have to talk about power mosfets, the ideal mosfets to use in this charger are those that have a minimum resistance and that can withstand a current of no less than 130 A each, this because although the source It is very efficient, there will always be a loss in heat that must be dissipated, which causes an increase in temperature, greatly reducing the conduction capacity of the mosfets and ultimately damaging the charger, it is for this reason that the most robust mosfets should be used. possible and with the lowest internal resistance.

I would also like to talk about the necessary inductor for this source since it is very important to take into account its saturation current, since we are talking about around 40A! that they will have to pass forces through the inductor and that it must withstand without saturating it and without changing its nominal inductance value.

The fact of using SMD components in this design is because the through components tend to have unwanted components such as parasitic resistors in the capacitor, which in high frequency designs such as this charger can cause deviations in the calculations made for this source, that is why The use of SMD components in addition to making a more compact board design possible, improves the performance of the circuit.

For this design he decided to use the IR2110 mosfet driver since it has a high switching speed in addition to a good current of up to 2.5 amps to turn the mosfets on and off, which makes it possible to turn on almost any type of mosfets without major complications and it is achieved practically anywhere.

To measure the charging current of the battery, I decided to use a resistance (shunt) to measure through the voltage drop in it, by OHM law clear the current that is passing through it, I decided to do it this way Since we will have currents of up to 40A, it makes it difficult to get a hall-effect current meter that allows us to measure that current.

At this point I say goodbye and send greetings to all the colleagues on the platform who in one way or another guided me to develop this renewable energy project, thank you.

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Oct 28,2021
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