Single‐phase AC‐AC Z‐source converter based on asymmetrical gamma structure with continuous input current and safe commutation strategy

Abstract

This paper examines a new topology of the AC‐AC Z‐source converter based on asymmetric Gama structure is proposed. The proposed converter has all the common features such as common ground between input and output, realizing the continuous input current and the ability of boost in‐phase and buck out of‐phase. In order to generate a high voltage gain in the proposed converter, a coupled inductor with Gama structure is used. In this structure, as the turn ratio approaches to one, it gives a higher voltage gain. In order to damping the voltage and current overshoots on the proposed converter switches, a safe commutation strategy is used. Due to the specific topology of the proposed converter, the output filter has been eliminated, so the size and cost of the proposed converter are reduced. Circuit analysis and performance principles are presented in detail and a laboratory prototype implemented to confirm the practicality of the proposed converter.

A single‐phase q‐source AC‐AC converter with continuous input current, safe commutation feature, and reduced bidirectional switch counts

“…The recommended converter efficiency is more than the converter in He et al 28 due to the fewer power electronics switches. Moreover, the converter efficiency compared to the converter in Mousavi et al 30 is better by utilizing q-source topology and an optimized switching strategy.…”

“…It has been plotted versus duty cycle, assuming that the maximum duty cycle is 0.3 and coupled inductor turns ratio n = γ Γ = 2, as depicted in Figure 7A. By considering ohmic losses of the inductors (r L and r Lm ) and losses of the power switches (R on_S and V bd_S ), the non-ideal voltage gain of the proposed converter and converters in He et al 28 and Mousavi et al 30 has been drawn as Figure 7B. This figure shows the voltage gain superiority of the proposed converter compared with others 28,30 when R on_S = 0.045 Ω, V bd_S = 0.9 V, and constant losses coefficient Z R is equal to 0.004.…”

“…In Table 1, the parameter γ Γ is considered equal n for the converter in Banaei et al 29 and Mousavi et al 30 According to relation (14), the proposed converter efficiency versus the duty cycle has been illustrated in Figure 8A for various the coupled inductor winding coefficient. Also, the voltage stresses on power switches of the q-source converter and competitors are compared in Figure 8B.…”

“…Converter in Minh-Khai et al 17 Converter in Banaei et al 19 Converter in He et al 28 Converter in Banaei et al 29 Converter in Mousavi et al 30 Proposed converter ρ EC and ρ EL are volume metric energy storage of capacitor and inductor, respectively. At the same time, according to the energy stored in capacitors, their volume is derived as given below:…”

“…A single‐phase Γ‐source AC‐AC topology with reduced device counts has been proposed in Banaei et al 29 However, this optimization yields a discontinuous input current. Mousavi et al 30 have offered another Γ source converter similar to the converter in Banaei et al 29 The input current variates continuously, but the voltage gain is not wide enough and flexible. Besides, the topology cannot be designed for identical primary and secondary windings.…”