TY - JOUR
T1 - High Step-Up Transformerless Inverter for AC Module Applications with Active Power Decoupling
AU - Roy, Jinia
AU - Xia, Yinglai
AU - Ayyanar, Raja
N1 - Funding Information:
Manuscript received January 23, 2018; revised April 28, 2018 and June 12, 2018; accepted July 2, 2018. Date of publication August 3, 2018; date of current version December 28, 2018. This work was supported in part by the Office of Energy Efficiency and Renewable Energy, and in part by the U.S. Department of Energy with North Carolina State University, Power America Institute, under Grant DE-EE0006521. (Corresponding author: Jinia Roy.) J. Roy is with the Power Systems Engineering Center, National Renewable Energy Laboratory, Golden, CO 80401 USA (e-mail: jinia.roy@ asu.edu).
Publisher Copyright:
© 1982-2012 IEEE.
PY - 2019/5
Y1 - 2019/5
N2 - This paper explores a power-conversion system for single-phase transformerless ac module application. A nonisolated high-gain dc-dc stage is coupled with a doubly grounded dynamic dc-link inverter to implement the microinverter topology. The front-end boost stage steps up the single-module voltage to a higher dc voltage, typically to 200 or 400 V as required for the following inverter stage. It is a hybrid of an interleaved boost and switched capacitor concept capable of achieving high gain while simultaneously maintaining reduced voltage and current stress, and thus lowering switching and conduction loss for most of the switches. By directly connecting the grid neutral to the photovoltaic (PV) negative, the doubly grounded voltage swing inverter has the advantage of zero capacitive-coupled common-mode ground currents, critical for transformerless PV inverters. The two dc links of the inverter stage share the double-line frequency power decoupling with a combination of higher value of mean voltage and relatively large 120-Hz ripple component-the dynamic dc-link approach. Through an optimization algorithm, the decoupling capacitance is minimized enabling an all-film capacitor implementation while satisfying the converter's operating constraints over a wide range of power factors. The simulation as well as experimental results from a GaN-based hardware prototype validate the converter's performance.
AB - This paper explores a power-conversion system for single-phase transformerless ac module application. A nonisolated high-gain dc-dc stage is coupled with a doubly grounded dynamic dc-link inverter to implement the microinverter topology. The front-end boost stage steps up the single-module voltage to a higher dc voltage, typically to 200 or 400 V as required for the following inverter stage. It is a hybrid of an interleaved boost and switched capacitor concept capable of achieving high gain while simultaneously maintaining reduced voltage and current stress, and thus lowering switching and conduction loss for most of the switches. By directly connecting the grid neutral to the photovoltaic (PV) negative, the doubly grounded voltage swing inverter has the advantage of zero capacitive-coupled common-mode ground currents, critical for transformerless PV inverters. The two dc links of the inverter stage share the double-line frequency power decoupling with a combination of higher value of mean voltage and relatively large 120-Hz ripple component-the dynamic dc-link approach. Through an optimization algorithm, the decoupling capacitance is minimized enabling an all-film capacitor implementation while satisfying the converter's operating constraints over a wide range of power factors. The simulation as well as experimental results from a GaN-based hardware prototype validate the converter's performance.
KW - Active power decoupling
KW - GaN-based converter
KW - doubly grounded inverter
KW - extended-duty-ratio (EDR) boost
KW - high-gain boost
KW - microinverter
KW - minimized capacitance
KW - module-integrated power converter
KW - transformerless PV inverter
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U2 - 10.1109/TIE.2018.2860538
DO - 10.1109/TIE.2018.2860538
M3 - Article
AN - SCOPUS:85051020930
SN - 0278-0046
VL - 66
SP - 3891
EP - 3901
JO - IEEE Transactions on Industrial Electronics
JF - IEEE Transactions on Industrial Electronics
IS - 5
M1 - 8425065
ER -