비대칭 전압 제어를 이용한 단상 임베디드 Z-소스 DC-AC 인버터

Abstract

In case of the conventional DC-AC inverter using two DC-DC converters with unipolar output capacitor voltages, for generating the AC output voltage, the output capacitor voltages of its each DC-DC converter must be higher than the DC input voltage. To solve this problem, this paper proposes a single-phase DC-AC inverter using two embedded Z-source converters with bipolar output capacitor voltages. The proposed inverter is composed of two embedded Z-source converters with common DC source and output AC load. The AC output voltage is obtained by the difference of the output capacitor voltages of each converter. Though the output capacitor voltage of converter is relatively low compared to the conventional method, it can be obtained the same AC output voltage. Moreover, by controlling asymmetrically the output capacitor voltage, the AC output voltage of the proposed system is higher than the DC input voltage. To verify the validity of the proposed system, a DSP(TMS320F28335) based single-phase embedded Z-source DC-AC inverter was made and the PSIM simulation was performed under the condition of the DC source 38V. As controlled symmetrically and asymmetrically the output capacitor voltages of each converter, the proposed inverter could produce the AC output voltage with sinusoidal waveform. Particularly, in case of asymmetric control, a higher AC output voltage was obtained. Finally, the efficiency of the proposed system was measured as 95% and 97% respectively in case of symmetric and asymmetric control.