thediyguy999 / mppt_buck_converter_synchronous

See video:

This is an Atmega 32U4 based Synchronous MPPT Buck Solar Charge Controller

Features:

• Programmable with Arduino IDE
• Input voltage 12 - 22V (36 cell solar panel)
• Output voltage 2.5 - 14.4V (single cell lithium up to 6 cell lead acid batteries can be directly charged)
• Simple MPPT (Maximum Power Point Tracking) solar charge controller for 18V solar panels
• Proper buck converter topology, which increases the current on the output side, not just PWM
• Sparkfun Pro Micro 5V, 16MHz or 3.3V, 8MHz (3.3v recommended, more efficient)
• ACS712 current sensor (5A version) on the output side
• Voltage dividers for voltage measurement on panel and output side
• Two N-channel mosfets, driven by IR2104 half bridge driver, inductor (synchronous buck converter, D5 increases efficiency)
• Third N-channel mosfet as efficient anti backfeed protection without the use of a lossy diode
• Supplied by the panel voltage, so it can't drain your battery during the night
• Working frequency 31.5kHz
• WARNING! This device is not intended to drive 5V USB devices directly. Do it at your own risk!
• Always use a regulated 5V USB adapter on the output! Otherwise, voltage glichtes may damage your USB device!
• This controller is COMMON NEGATIVE
• 4 operation modes: MPPT, CV, CC, Idle
• SD card data logger for time, voltage and current. You can import the txt files in Excel
• WARNING! Always adjust output voltage and output current limits according to your battery type, before you connect the battery
• Efficiency between 72% and 92%

New in V 1.0:

• Initial commit, tested with my 10W and 20W solar panels, charging my DIY USB power bank with 8 18650 cells in parallel. Two TP4056 lithium charger modules in paralel on the output
• An anti backfeed diode on the output is required, if you charge batteries directly! Otherwise, your low side mosfet may blow up!!

New in V 1.1:

• Anti backfeed diode is not required anymore, MOSFET Q1 added as anti backfeed protection. It is driven with 16V by a separate charge pump circuit (D3, D4, D6, C8)
• Direct charging tested with 6.6Ah, 12V Lead Acid battery and 4 18650 cells in parallel, charge current up to 3.8A
• Software changed: MOSFET Q3 protection (this is very critical, because it can short the battery to GND!)
• Freewheel diode D5 added to improve efficiency
• LM317T regulator replaced with a more efficient MP1584EN step down module

New in V 1.2:

• Optimized for 4.2V 1S LiPo 18650 direct charging

New in V 1.3:

• Display now using u8x8 instead of u8g2 in order to save flash memory
• Ah is displayed as well, not just Wh.
• Splash screen shows SW version
• Switchable display content, using Menu button
• Pot is used for manual / automatic MPPT tracking instead of output voltage adjustment
• tested with my 10W and 20W solar panels, charging my DIY USB power bank with 8 18650 cells in parallel. The TP4056 board is not used as chrarger anymore, just as BMS (overcharging, overdischarging, overcurrent). The 18650 cells are connected to the B+ and B- terminals, the charger and the USB aoutput stepup modules to the OUT+ and OUT- terminals. The output voltage is 4.2v , which is the maximum charge voltage of an 18650 cell.

To do:

• Adding a configuration menu, using the buttons
• Changing the inductor to allow 5A charge current
• Designing a proper PCB

Usage

See pictures

Also have a look at the pdf schematic.

(c) 2018 TheDIYGuy999

mppt_buck_converter_synchronous's Issues

mosfet los side

hi TheDIYGuy999
can you help me with my circuit? I have build my own with different code. I can share the code for you to examine. Right now having a problem burning my lowside mosfet.
i am trying to build max solar 84v input if okay. can you explain how your charge pump prevent blowing lowside mosfet. can you examine my code? i have different driver that can enable. synchronous and non-synchronous mode.