*Article* **Transformerless Quasi-Z-Source Inverter to Reduce Leakage Current for Single-Phase Grid-Tied Applications**

#### **Woo-Young Choi \* and Min-Kwon Yang**

Division of Electronic Engineering, Chonbuk National University, Jeonju 561-756, Korea; mkyang@jbnu.ac.kr **\*** Correspondence: wychoi@jbnu.ac.kr; Tel.: +82-063-270-4218

Received: 13 February 2019; Accepted: 4 March 2019; Published: 12 March 2019

**Abstract:** The conventional single-phase quasi-Z-source (QZS) inverter has a high leakage current as it is connected to the grid. To address this problem, this paper proposes a transformerless QZS inverter, which can reduce the leakage current for single-phase grid-tied applications. The proposed inverter effectively alleviates the leakage current problem by removing high-frequency components for the common-mode voltage. The operation principle of the proposed inverter is described together with its control strategy. A control scheme is presented for regulating the DC-link voltage and the grid current. A 1.0 kW prototype inverter was designed and tested to verify the performance of the proposed inverter. Silicon carbide (SiC) power devices were applied to the proposed inverter to increase the power efficiency. The experimental results showed that the proposed inverter achieved high performance for leakage current reduction and power efficiency improvement.

**Keywords:** quasi-z-source inverter; grid-tied; leakage current; power efficiency
