Single-Stage Single-Phase Current Source Inverter for Standalone Applications

The current source inverters (CSI) are considered more reliable than their voltage source counterparts due to the inherent current-limiting feature. This is particularly interesting for many applications, such as battery energy storage, where there is a possibility of very high short-circuit currents. In addition, CSI can provide an inherent voltage boost capability, allowing integration of extra-low voltage batteries with 230 Vac loads for standalone applications. For the past few years, CSI has not garnered much attention due to the unavailability of switches with reverse voltage blocking capability. However, with the emergence of new technologies based on wide bandgap materials and monolithic devices, CSI can potentially provide effective solutions for such applications. In this paper, a CSI is proposed as an interface between a ±48 V battery bank and a 230 Vac load. To minimize the forward voltage-drop across the switches of the current source inverter, silicon carbide MOSFETs-based four-quadrant switches are employed. In addition, a unipolar carrier-based modulation is proposed and implemented. This modulation technique facilitates easier control of overlap-time and minimizes its effect on the power quality output of the inverter. To validate this proposal, a 700 W prototype was built, and laboratory tested.