Experimental observation of destabilization in a DC bus system and its stabilization with delayed feedback control

Abstract

Direct-current (DC) bus systems are expected to play a significant role in next-generation power technology because of the rapid development of power electronics. However, it is well known that the bus line voltage can become unstable when electric power through the bus line is constantly consumed by loads. Bifurcation analysis of this instability has been previously performed. It has been reported that in theory, delayed feedback control, which was developed to stabilize chaotic systems, can suppress this instability. For practical applications, it is necessary to confirm these analytical results with circuit experiments. In this study, the dynamics of a DC bus system without control and with delayed feedback control are experimentally investigated. The following three main results are obtained. First, bifurcation phenomena are experimentally found to occur with an increase in power consumption in the DC bus system without control. Second, it is experimentally found that delayed feedback control stabilizes the operating point. These results provide experimental evidence that delayed feedback control can be utilized as a stabilization method for DC bus systems. Third, it is experimentally demonstrated that the delayed feedback controller can track the operating point when the power consumption changes slowly, but not when it changes rapidly. A frequency-domain analysis is conducted to analytically estimate the upper limit of the acceptable power consumption rate of change. The estimated upper limit is useful for designing the controller and restricting the change rate of power consumption.