FUZZY GAIN SCHEDULING OF PI CONTROLLER FOR DISTRIBUTED CONTROL OF PARALLEL AC/DC CONVERTERS

This paper presents a fuzzy gain scheduling of proportional-integral (FGPI) controller which is used for controlling the output voltage of an AC/DC converter. In the proposed system, the converter is composed of isolated CUK power factor correction circuits those parallel-connected for increasing power capacity. For the flexibility and modularity purpose, each converter module employs an individual microcontroller to control the power converter operation and communicate among other converter modules for load current sharing. The microcontroller in each module communicates to each other via RS485 serial communication bus. To avoid the data collision on the communication bus, a synchronization signal is used to synchronize the time slot of microcontrollers in the system for sending and receiving data. The FGPI controller is used to improve dynamic response of the output voltage loop while an analog hysteresis current controller is used to control the input current of each converter. Three-250 W/module AC/DC converters are designed and built to verify the operation of the proposed system. The experimental results show that the proposed system provides fast response of the output voltage control, and that current sharing of each module is quite good and that a high input power factor is achieved.