mppt vs pwm
Hi, A nice little video comparing mppt vs pwm with the batteries in bulk mode. mppt vs pwm
Forum Discussion
BFL said,
"There is high frequency PWM and "low frequency" PWM. The "PWM" 12v controller uses low frequency PWM to "control" when it is stopping voltage from going any higher after it starts controlling."
I think maybe that goes back to the debate over on/off shunt controllers vs. pwm. When pwm first came out, the 'shunt camp' argued on/off was in fact pwm, but low frequency pwm, not high frequency pwm. From what I can tell so far, it was never an issue of low vs. high frequency, but an issue of linear vs. switching technology. (but I could be mistaken about that). Switching, by its very nature IS high frequency. So there may be some confusion about what "high frequency" is even referring to? This is why I'm compelled to investigate the whole issue further. To this day, you can still buy shunt controllers, and some still swear by their superiority to "high frequency" pwm.
Morningstar's whole arguement for the superiority of pwm is based on findings by Sandia, that indicated two things, in particular;
1) "It appears the number of times a system cycles off and on, during a day in regulation, has a much stronger impact on battery soc, than the max voltage"
IOW, higher frequency pwm results in improved battery acceptance and thus higher soc, and
2) max voltage has little effect, while "reconnect voltage" has a strong impact on resulting soc.
This goes back to the other article, where the pro- shunt guy argued that pwm was being unfairly compared to on/off controllers with poorly calibrated max/reconnect setpoints. But either way, what we now consider as pwm is apparently high frequency pwm. Of course, I could be mistaken?
Is there generally a difference in the actual pwm frequency used by PWM and MPPT controllers?
"There is high frequency PWM and "low frequency" PWM. The "PWM" 12v controller uses low frequency PWM to "control" when it is stopping voltage from going any higher after it starts controlling."
I think maybe that goes back to the debate over on/off shunt controllers vs. pwm. When pwm first came out, the 'shunt camp' argued on/off was in fact pwm, but low frequency pwm, not high frequency pwm. From what I can tell so far, it was never an issue of low vs. high frequency, but an issue of linear vs. switching technology. (but I could be mistaken about that). Switching, by its very nature IS high frequency. So there may be some confusion about what "high frequency" is even referring to? This is why I'm compelled to investigate the whole issue further. To this day, you can still buy shunt controllers, and some still swear by their superiority to "high frequency" pwm.
Morningstar's whole arguement for the superiority of pwm is based on findings by Sandia, that indicated two things, in particular;
1) "It appears the number of times a system cycles off and on, during a day in regulation, has a much stronger impact on battery soc, than the max voltage"
IOW, higher frequency pwm results in improved battery acceptance and thus higher soc, and
2) max voltage has little effect, while "reconnect voltage" has a strong impact on resulting soc.
This goes back to the other article, where the pro- shunt guy argued that pwm was being unfairly compared to on/off controllers with poorly calibrated max/reconnect setpoints. But either way, what we now consider as pwm is apparently high frequency pwm. Of course, I could be mistaken?
Is there generally a difference in the actual pwm frequency used by PWM and MPPT controllers?
