*Article* **Ripple Vector Cancellation Modulation Strategy for Single-Phase Quasi-Z-Source Inverter**

#### **Yufeng Tang, Zhiyong Li \*, Yougen Chen and Renyong Wei**

School of Automation, Central South University, Changsha 410083, China **\*** Correspondence: lizy@csu.edu.cn; Tel.: +86-138-7312-7689

Received: 6 August 2019; Accepted: 23 August 2019; Published: 30 August 2019

**Abstract:** The double-frequency (2ω) power flows through the DC side of the single-phase quasi-Z-source inverter (QZSI) leads to the 2ω voltage ripple of capacitors and 2ω current ripple of inductors. This paper proposes a ripple vector cancellation modulation strategy (RVCMS) based on the thought of ripple vector cancellation. By analyzing the mechanism of ripple generation and transmission, we can obtain a variation of a shoot-through duty cycle to generate a compensated 2ω ripple used to cancel the 2ω current ripple of inductors caused by the 2ω ripple of DC link current, and the 2ω compensated variation of a shoot-through duty cycle with a specific amplitude and phase is added to the constant shoot-through duty cycle. Finally, simulation and experimental results demonstrate the correctness and effectiveness of the proposed modulation strategy for the single-phase QZSI.

**Keywords:** quasi-Z-source inverter; double-frequency ripple; ripple vector cancellation; shoot-through duty cycle; modulation
