I am using 2 of the following H-Bridge to control 2 x 24V 350W electric scooter DC motors. The power is from 2 x 12V 12AH SLA batteries in series.
EDIT: These are the entire schematic and PCB photos:
The PWM signal controlling this H-Bridge is in locked-antiphase mode at 40KHz.
This H-Bridge works great except that only when the motor brakes and changes direction SWIFTLY, this will make the microcontroller hang oweing to electrical ripples/noise.
I am new to H-Bridges and I am unable to see how regenerative current from the motor (generated when the motor slows down and changes direction) is circulated around the circuit. Would it be the cause of my problem? How to tackle it?
A friend of mine who designs electronic circuits suggests using a 0.1uF capacitor in series with a high power resistor (5W) and connecting both between the motor terminals, in order to absorb the power generated by the motor whenever it works as a power generator. Has anyone done this before?
I am grateful to any help from you!
Ah, I forgot to put in the schematic, but C6 and C9 are 1000uF each. The half bridge driver is IRS2184S. If you want to see the schematic clearer, please do a "Save image as". Thanks in advance.
EDIT 17 Nov 2014 Based on Andy aka's & JonRB's answers:
Thank you both so much for your invaluable advice. I believe you are poiting me in the right direction now!
I plan to get this circuit board redesigned, fabricated and tested with updated result, and these are the changes I am going to make:
- Since a 4 layer PCB is not possible here, I intend to use a DIP version of the micro (pitch=2.54mm) so that I can make a full earth plane around the micro
- The earth plane of the signal part will be connected directly to Battery (-) rather than to that of the power side, so that return current of the power side goes directly to the battery rather than polluting the signal side
I would like to hear your comments on the following if possible:
- If I make the power side and signal side into 2 separate PCBs connected by some wires, with GND of each connected directly to Battery (-), will this be even cleaner? Would you recommend it?
- @RonRB: is the braking circuit a must (to make the board run without hanging/data corruption)? I guess we can live without it?
As a self-taught electronics enthusiast, I have been pulling my hair on this problem for a month now, hopefully I will have it resolved thanks to your help.