Technicians, through a combination of theoretical analysis and experimental exploration, have made corresponding improvements to the auxiliary transformer and control circuit, ultimately resolving the issue. The solution involves: adjusting the auxiliary transformer's turns ratio, changing the primary winding turns Np, reducing the primary-secondary turns ratio, thereby decreasing the duty cycle at low voltages to be significantly less than the 45% upper limit specified by UC3844; tuning the RC filter network in the current feedback loop of the UC3844, and after numerous experiments, achieving a more ideal set of parameters, with an increased filter capacitor. The same test was then conducted on the same secondary winding of the auxiliary transformer under identical conditions. Aviation ground power 2, 36V aviation power 1, 400HZ frequency converter power supply 7, 115/200V power supply.
From these four waveforms, it can be observed that the improved auxiliary power supply maintains greater stability in both high and low AC input conditions (and with a lower startup working voltage than before), as well as under no load or heavy load conditions. The working waveforms are more stable and the pulse widths are more symmetrical and balanced compared to the previous improvement. Moreover, the load-bearing capacity is notably superior to that of the previous version. In comparison, the improved duty cycle is 7% lower than the previous duty cycle under low input voltage, indicating that the AC input of the auxiliary power supply can still maintain stable output voltage under increased load, and its load-bearing capacity is significantly stronger than before. The improvement in the auxiliary power supply has yielded clear results.
