So how do I change nga the output of a UPS from 60Hz to 400Hz? I cant think of anything inside a UPS to tweak on to change the output frequency.
I never hacked a UPS before. I am hoping somebody who does will help us here, maybe some member working in APC. Nevertheless, I could speculate. So take the following with the proverbial grain of salt:
1. Get a schematic. This part could be the toughest to tackle.
2. Locate the PWM generator section, and find the reference sine wave signal.
3. Change this signal to 400Hz. You may have to build your own 400Hz sine reference.
Watch out for the following scenario:
- The system controller may detect this change as a fault and may refuse to start PWM generation. You might need to add a circuit to fool the microcontroller into thinking everything is OK.
- Changing the frequency may also call for a modification in the feedback loop to keep the system stable.
- Things may turn out to be more complicated if the feedback loop passes though the microcontroller.
Get us a schematic so that we can do some real work here.