• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.21 no.3
• /
• pp.56-61
• /
• 2007

In this paper, a circulating current reduction approach for the parallel operation of fuelcell systems with Z-source inverters is investigated. The carrier phase shifted SPWM(Sinusoidal Pulse Width Modulation) is used as a modulation method since it has an advantage in reducing output current harmonics. However, when this technique is applied to the parallel operation of Z-source inverters, it additionally produces circulating currents. A coupled circulating current reactor is used to reduce circulating current generated by the parallel operation of Z-source inverters and to reduce output current harmonics. The proposed circulating current reduction approach using coupled circulating current reactors is verified through simulation and experiment.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.10 no.5
• /
• pp.443-449
• /
• 2005

In this paper, parallel operation systems with Z-source Inverters for the fuel cell systems are discussed. The carrier phase shifted SPWM(Sinusoidal Pulse Width Modulation) has an advantage in reducing harmonics of output current. However when this technique applies in parallel operation of Z-source inverters, it additionally produces circulating currents. The circulating current is analyzed and a method to prevent the circulating current is applied to the parallel operation systems of Z-source inverters. To maintain high performance with reduced circulating current in inverter output and low harmonic components in load current, circulating current reactors are used. The proposed approach is verified through simulation and experiment.

• Journal of Power Electronics
• /
• v.10 no.2
• /
• pp.146-154
• /
• 2010

In this paper two dual output current-type inverters are proposed. These inverters have been called a current source nines-witch inverter and a current-type z-source nine-switch inverter by the authors. The proposed inverters have two independent current source outputs. Compared to two independent current source inverters, the proposed converters are implemented with fewer semiconductor switches. Space vector modulation (SVM) is proposed for these converters. Simulation results show the validity and performance of the proposed inverters.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
• /
• v.5B no.1
• /
• pp.6-12
• /
• 2005

This paper presents Z-source inverters, their controls,, and their systems for motor drives. System configurations, analysis, controls, and unique features of the new Z-source motor drive systems will be summarized and given. Simulation and experimental results demonstrate advantageous features over the traditional voltage- and current-source inverter systems.

• Journal of Power Electronics
• /
• v.14 no.5
• /
• pp.918-925
• /
• 2014

This study presents an extended boost single-phase qZ-source DC-AC inverter for a single-phase photovoltaic system. Unlike the previously proposed single-phase qZ-source and semi-qZ-source inverters that achieve the same output voltage as that of the traditional voltage-fed full-bridge inverter, the proposed inverter can obtain higher output than input voltage. The proposed inverter also shares a common ground between DC input voltage and AC output voltage. Thus, possible ground leakage current problem in non-isolated grid-tied inverters can be eliminated with the proposed inverter. A 120 W prototype inverter is built and tested to verify the performance of the proposed inverter.

• Journal of Power Electronics
• /
• v.13 no.1
• /
• pp.9-19
• /
• 2013

In this paper, a ripple input current embedded switched-inductor Z-source inverter (rESL-ZSI) and a continuous input current embedded switched-inductor Z-source inverter (cESL-ZSI) are proposed by inserting two dc sources into the switched-inductor cells. The proposed inverters provide a high boost voltage inversion ability, a lower voltage stress across the active switching devices, a continuous input current and a reduced voltage stress on the capacitors. In addition, they can suppress the startup inrush current, which otherwise might destroy the devices. This paper presents the operating principles, analysis, and simulation results, and compares them to the conventional switched-inductor Z-source inverter. In order to verify the performance of the proposed converters, a laboratory prototype was constructed with 60 $V_{dc}$ input to test both configurations.

• Journal of IKEEE
• /
• v.21 no.2
• /
• pp.166-169
• /
• 2017

In this paper, maximum boost discrete PWM(DPWM) method of Z-Source Inverter(ZSI) is proposed. In general, a DPWM method is used to reduce the switching losses of the inverters and increase the efficiencies. The maximum boost PWM method of Z-Source Inverters is combined with the DPWM method. The proposed Maximum boost DPWM of ZSI is analyzed and it shows how to reduce the switching losses of ZSI. An experimental system has been built and tested to verify the effectiveness of the proposed method.

• Journal of IKEEE
• /
• v.19 no.1
• /
• pp.73-79
• /
• 2015

In this paper, maximum boost space vector pulse-width modulation(MBSVPWM) strategy of Z-Source Inverters(ZSIs) is proposed. Conventional space vector pulse-width modulation(SVPWM) method of Voltage Source Inverters(VSIs) is modified to produce unique PWM patterns that realize the maximum boost control of ZSIs. This proposed method minimizes the switching power losses of ZSIs by reducing the numbers of the shoot-through states. Moreover, some switches keep ON state and the switching transitions do not occur during the specific sectors. An experimental system has been built and tested to verify the effectiveness of the proposed strategy.

• Journal of Power Electronics
• /
• v.15 no.5
• /
• pp.1217-1226
• /
• 2015

In a grid-connected photovoltaic (PV) system, the traditional Z-source inverter uses a low frequency transformer to ensure galvanic isolation between the grid and the PV system. In order to combine the advantages of both Z-source inverters and transformerless PV inverters, this paper presents a modified single-phase transformerless Z-source PV grid-connected inverter and a corresponding PWM strategy to eliminate the ground leakage current. By utilizing two reversed-biased diodes, the path for the leakage current is blocked during the shoot-through state. Meanwhile, by turning off an additional switch, the PV array is decoupled from the grid during the freewheeling state. In this paper, the operation principle, PWM strategy and common-mode (CM) characteristic of the modified transformerless Z-source inverter are illustrated. Furthermore, the influence of the junction capacitances of the power switches is analyzed in detail. The total losses of the main electrical components are evaluated and compared. Finally, a theoretical analysis is presented and corroborated by experimental results from a 1-kW laboratory prototype.

• Proceedings of the KIPE Conference
• /
• 2013.07a
• /
• pp.376-377
• /
• 2013

본 연구에서는 양방향 인덕터 대신 단방향 변압기 셀을 이용한 Switched Trans Z-source inverter, Switched Trans Quasi Z-source inverter, Switched Trans-inductor Quasi Z-source inverter의 전압 이득 및 스트레스를 비교하였다.