A single-phase half-bridge current source inverter (CSI) topology with reduced power semiconductor count for grid-connected applications

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Alavi Eshkaftaki, Seyed Reza
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This thesis proposes a new single-phase Current Source Inverter (CSI) topology for grid-connected application. This new topology aims to increase the lifetime and the reliability of an inverter by eliminating input Electrolytic Capacitor (E-Cap) and decreasing the semiconductor count. It is known that in power electronic systems, E-Caps have a very short lifetime and semiconductor devices are prone to fail. Thus, eliminating and decreasing their number lower the risk of failure in the system. The proposed inverter has no DC link capacitor and processes the power with only two active switches. The inverter utilizes two Reverse-Blocking (RB) Insulate Gate Bipolar Transistors (IGBTs) to decrease the semiconductor count as few as possible. The proposed topology is a dual circuit of Half-Bridge (HB) Voltage Source Inverter (VSI); And similarly, it requires two individual current sources instead of two individual voltage sources. These two individual current sources are created by splitting DC input current by a low-frequency power transformer. The development of the topology, operating principles, and steady state characteristics are presented. A 250 W laboratory prototype is built and experimental results for a simple input voltage source and a PV panel are demonstrated to verify theoretical concepts.
Current Source Inverter, CSI, Single-phase, Dual circuit, Grid-connected inverter, Electrolytic capacitor, Inductor, VSI, Voltage Source Inverter