I am making a self balancing scooter which runs off 2 x 12V SLA batteries connected in series to make 24V. Everything works as expected except for the power supply which makes me pull most of the hair in my head for 2 weeks now. Hope someone could help.
The 2 24V motors run off the batteries directly. Now for my scooter, I need a +12V line for the half bridge drivers, and a +5V line for the signal part. For +12V I am using a LM2576-12 hooked to the batteries (+24) and for the +5V signal I am using a LM2596 ADJ, also hooked directly to the batteries (or is it supposed to be hooked to the output of LM2576-12 for better performance??).
The problem is that, when the motors are under load this power supply system makes the microcontroller hang (or reset I am not too sure, since everytime I have to try to turn off the power switch immediately, because the motor keeps running with whatever value they are fed with right before this happens), usually within 1 minute of riding, which is very dangerous when someone is onboard.
I have read and re-read the datasheet of LM2576 and LM2596 many times, and have tried many settings, from recommended to different values of capacitor and inductor. For the diode, I am using the SS34.
I guess its not because of electromagnetic interference, since while I do have the PCB located near the motors, the PCB is actually put inside a homemade Faraday cage which is grounded (Battery -), and the motor cases are also grounded. Plus that the microcontroller only hangs when motors are under load (i.e. me on board), especially when I go from forward to backward.
The motor controller is self made, using 8 x AUIRF2804S MOSFETs. I also put 4 x 1000uF caps between the motors and the +24V.
Would anyone be so kind to throw some light. What would a power supply for this kind of application is supposed to be?