Development of an iterative learning current control method for power electronics converters

Current control has an important role in power electronics applications. Current control performance affects dynamic response and system stability directly in power electronics converters. In this thesis study, hysteresis current control (HCC), which has fast dynamic response and stability, is performed. Analog hysteresis current control, which is an conventional current control method, is not preferred because of variable switching frequency although it is an effective method in terms of dynamic response and stability. Because variable switching frequency causes problems like electromagnetic interference (EMI) and filter design difficulty. Therefore, the designers prefer constant frequency control methods. However, these control methods are required detailed analyzes and the design becomes difficult in these control methods. HCC is advantageous according to the other control methods in terms of dynamic response and stability. In this thesis study, an effective current control method is performed for power electronics converters removing disadvantages of HCC. Switching frequency is variable in HCC and the current may exceed the hysteresis band because of the dead time. Digital HCC is realized to solve these problems. Hysteresis band is changed adaptively with digital HCC. Variation in DC bus voltages, value of filter inductance, sampling period and slope of current reference cause limitations in HCC and aimed control can not be realized. In order to remove effect of these parameters, hysteresis band is controlled as adaptive using an iterative learning control (ILC) method and succesful results are obtained. In this thesis study, the results are achieved for two level single phase grid connected voltage source inverter (VSI).