Nowadays, most of the ac-dc power module parallel output design schemes in Mainland China have applied the active method. This type of method uses the current-sharing bus method, and each ac-dc power supply module is correlated with each other, and the output current of each ac-dc power supply module is sampled to adjust the output working voltage of each ac-dc power supply module. The method completes current sharing and has the advantage of high efficiency. According to the difference between the generation method of the current sharing busbar and the adjustment control method, there are 12 main methods of the active method. At least the characteristics are good and the practicality is extremely strong. The average current amount + outer loop adjustment method and the larger current amount + outer loop Adjustment method. Here, people can design and conceive a certain current-sharing electric control system based on the larger amount of current + outer loop adjustment method. The schematic diagram of the ac-dc power module of the operating system is shown in the figure.

Schematic diagram of current sharing power module

In the figure, the main parameter feedback is the output current sampling of the ac-dc power module, and the main parameter co-on is the current sharing bus. From the figure, we can see that the output sampling current of all ac-dc power modules can be connected with the diode and the current sharing bus bar, so the current sharing bus slot is marked with a larger current from beginning to end. V1 and R1, R2, R6, and R7 form a differential signal operational amplifier circuit, and its output is the difference between the current of the ac-dc power module and the larger current. The difference and the reference are added to the PI controller according to the proportion of 1:10 as a new input.

If the output current of the power module is lower than the larger current, the output of the differential signal power circuit and the new standard will increase the current of the power module. In that case, the output current of all power modules is adjusted to a larger current at all times. Since the diode has a voltage drop of about 0.7V, this will cause the larger current module to be in a rotation state from beginning to end, so this type of current sharing method is also called unmaintained current sharing.

One problem that must be paid special attention to is that in this plan, you need to achieve parallel current sharing of multiple power modules. In addition to the current sharing circuit, the output terminal of the main circuit needs to be connected in series 1 A diode or a large inductor. This is to prevent the power supply module with an excessively large output working voltage from treating the control module with a small output working voltage as a load, which will cause the system software to be unstable and reduce the overall efficiency of the system.