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IEEE TRANSACTIONS ON INDUSTRIAL INFORMATICS, VOL. 10, NO. 1, FEBRUARY 2014 399

An Effective Control Method for Quasi-Z-SourceCascade Multilevel Inverter-Based Grid-TieSingle-Phase Photovoltaic Power System

Yushan Liu, Student Member, IEEE, Baoming Ge, Member, IEEE, Haitham Abu-Rub, Senior Member, IEEE,and Fang Z. Peng, Fellow, IEEE

Abstract—An effective control method, including system-levelcontrol and pulsewidth modulation for quasi-Z-source cascademultilevel inverter (qZS-CMI) based grid-tie photovoltaic (PV)power system is proposed. The system-level control achieves thegrid-tie current injection, independent maximum power pointtracking (MPPT) for separate PV panels, and dc-link voltage bal-ance for all quasi-Z-source H-bridge inverter (qZS-HBI) modules.The complete design process is disclosed. A multilevel space vectormodulation (SVM) for the single-phase qZS-CMI is proposedto fulfill the synthetization of the step-like voltage waveforms.Simulation and experiment based on a seven-level prototype arecarried out to validate the proposed methods.

Index Terms—Cascade multilevel inverter (CMI), photovoltaic(PV) power system, quasi-Z-source inverter, space vector modula-tion (SVM).

I. INTRODUCTION

A recent upsurge in the study of photovoltaic (PV) powergeneration emerges, since they directly convert the solar

radiation into electric power without hampering the environ-ment. However, the stochastic fluctuation of solar power is in-consistent with the desired stable power injected to the grid,owing to variations of solar irradiation and temperature. To fullyexploit the solar energy, extracting the PV panels’ maximumpower and feeding them into grids at unity power factor be-come the most important. The contributions have been made bythe cascade multilevel inverter (CMI) [1], [2]. Nevertheless, theH-bridge inverter (HBI) module lacks boost function so that the

Manuscript received October 17, 2012; revised January 31, 2013; acceptedAugust 20, 2013. Date of publication August 29, 2013; date of current versionDecember 12, 2014. This work was supported by the Qatar National ResearchFund, a member of Qatar Foundation, under Grant NPRP-EP X-033-2-007.Paper no. TII-12-0726.Y. Liu is with the School of Electrical Engineering, Beijing Jiaotong Uni-

versity, Beijing 100044, China, and also with the Department of Electrical andComputer Engineering, Texas A&M University at Qatar, Doha 23874, Qatar(e-mail: [email protected]).B. Ge is with the School of Electrical Engineering, Beijing Jiaotong Uni-

versity, Beijing 100044, China, and also with the Department of Electrical andComputer Engineering, Michigan State University, East Lansing, MI 48824USA (e-mail: [email protected]; [email protected]).H. Abu-Rub is with the Department of Electrical and Computer En-

gineering, Texas A&M University at Qatar, Doha 23874, Qatar (e-mail:[email protected]).F. Z. Peng is with the Department of Electrical and Computer Engineering,

Michigan State University, East Lansing, MI 48824 USA (e-mail: [email protected]).Color versions of one or more of the figures in this paper are available online

at http://ieeexplore.ieee.org.Digital Object Identifier 10.1109/TII.2013.2280083

inverter KVA rating requirement has to be increased twice witha PV voltage range of 1:2; and the different PV panel outputvoltages result in imbalanced dc-link voltages. The extra dc–dcboost converters were coupled to PV panel and HBI of the CMIto implement separate maximum power point tracking (MPPT)and dc-link voltage balance [3], [4]. However, each HBImoduleis a two-stage inverter, and many extra dc–dc converters notonly increase the complexity of the power circuit and controland the system cost, but also decrease the efficiency.Recently, the Z-source/quasi-Z-source cascade multilevel

inverter (ZS/qZS-CMI)-based PV systems were proposed in[5]–[8]. They possess the advantages of both traditional CMIand Z-source topologies. For example, the ZS/qZS-CMI: 1)has high-quality staircase output voltage waveforms withlower harmonic distortions, and reduces/eliminates output filterrequirements for the compliance of grid harmonic standards;2) requires power semiconductors with a lower rating, andgreatly saves the costs; 3) shows modular topology that eachinverter has the same circuit topology, control structure andmodulation [1], [2]; 4) most important of all, has indepen-dent dc-link voltage compensation with the special voltagestep-up/down function in a single-stage power conversion ofZ-source/quasi-Z-source network, which allows an independentcontrol of the power delivery with high reliability [9]–[11]; and5) can fulfill the distributed MPPT [6], [8].In order to properly operate the ZS/qZS-CMI, the power

injection, independent control of dc-link voltages, and thepulsewidth modulation (PWM) are necessary. The work in[5] and [7] focused on the parameter design of the ZS/qZSnetworks and the analysis of efficiency. The work in [8] pre-sented the whole control algorithm, i.e., the MPPT control ofseparate quasi-Z-source H-bridge inverter (qZS-HBI) module,and the grid-injected power control, whereas the phase-shiftedsinewave PWM (PS-SPWM) is the only existing PWM tech-nique for the single-phase ZS/qZS-CMI. The PS-SPWMconsumes more resources to achieve the shoot-through statesbecause two more references are compared with the carrierwaveform. Additionally, the ZS/qZS-CMI based grid-tiePV system has never been modeled in detail to design thecontrollers.The main contributions of this paper include: 1) a novel mul-

tilevel space vector modulation (SVM) technique for the single-phase qZS-CMI is proposed, which is implemented without ad-ditional resources; 2) a grid-connected control for the qZS-CMIbased PV system is proposed, where the all PV panel voltagereferences from their independent MPPTs are used to controlthe grid-tie current; the dual-loop dc-link peak voltage control

1551-3203 © 2013 IEEE

400 IEEE TRANSACTIONS ON INDUSTRIAL INFORMATICS, VOL. 10, NO. 1, FEBRUARY 2014

is employed in every qZS-HBI module to balance the dc-linkvoltages; 3) the design process of regulators is completely pre-sented to achieve fast response and good stability; and 4) simu-lation and experimental results verify the proposed PWM algo-rithm and control scheme.This paper is organized as follows. An overview of the

whole system with control strategy is presented in Section II.Section III focuses on the system modeling and grid-connectedcontrol. Section IV addresses the proposed multilevel SVMtechnique. Section V designs the regulators; the proposedstrategy is verified by simulation and experimental results inSection VI. Finally, a conclusion is given in Section VII. Notethat, in the derivations of the paper, all of the symbols with “ ”denote the amplitude, and those with “ ” denote the average.

II. DESCRIPTION OF QZS-CMI-BASED GRID-TIEPV POWER SYSTEM

Fig. 1 shows the discussed qZS-CMI-based grid-tie PV powersystem. The total output voltage of the inverter is a series sum-mation of qZS-HBI cell voltages. Each cell is fed by an inde-pendent PV panel. The individual PV power source is an arraycomposed of identical PV panels in parallel and series. A typ-ical PVmodel in [12] is performed by considering both the solarirradiation and the PV panel temperature.

A. qZS-CMI

The qZS-CMI combines the qZS network into each HBImodule. When the th qZS-HBI is in nonshoot-through states,it will work as a traditional HBI. There are

(1)

while in shoot-through states, the qZS-HBI module does notcontribute voltage. There are

(2)

For the qZS-CMI, the synthesized voltage is

(3)

where is the output voltage of the th PV array; isthe dc-link voltage of the th qZS-HBI module; andrepresent the shoot-through duty ratio and boost factor of theth qZS-HBI, respectively, is the output voltage of the thmodule, and is the switching function of theth qZS-HBI.

B. Control Strategy

The control objectives of the qZS-CMI based grid-tie PVsystem are: 1) the distributed MPPT to ensure the maximumpower extraction from each PV array; 2) the power injectionto the grid at unity power factor with low harmonic distortion;3) the same dc-link peak voltage for all qZS-HBI modules. Theoverall control scheme of Fig. 1 is proposed to fulfill thesepurposes.For achieving the first two goals, the closed loops are

employed, as Fig. 1(a) shows.

Fig. 1. (a) qZS-CMI based grid-tie PV power system. (b) DC-link peak voltagecontrol.

1) Total PV array voltage loop adjusts the sum of PV arrayvoltages tracking the sum of PV array voltage referencesby using a proportional and integral (PI) regulator .Each PV array voltage reference is from its MPPT controlindependently.

2) Grid-tie current loop ensures a sinusoidal grid-injected cur-rent in phase with the grid voltage. The total PV arrayvoltage loop outputs the desired amplitude of grid-injectedcurrent. A Proportional + Resonant (PR) regulator enforcesthe actual grid current to track the desired grid-injected ref-erence. The current loop output’s total modulation signalsubtracts the modulation signal sum of the second, third,, and th qZS-HBI modules to get the first qZS-HBI

module’s modulation signal.

LIU et al.: EFFECTIVE CONTROL METHOD FOR qZS-CMI-BASED GRID-TIE SINGLE-PHASE PHOTOVOLTAIC POWER SYSTEM 401

Fig. 2. Block diagram of the proposed grid-tie control with the model for the qZS-CMI based PV system.

3) The separate PV array voltage loops regulate theother PV array voltages to achieve their own MPPTsthrough the PI regulators, such as to ,respectively. With the total PV array voltage loop con-trol, the PV arrays fulfill the distributed MPPT. In ad-dition, the voltage feed forward control is used to generateeach qZS-HBI module’s modulation signal, which will re-duce the regulators’ burden, achieve the fast dynamicresponse, and minimize the grid voltage’s impact on thegrid-tie current.

For the third goal, the dc-link peak voltage is adjusted in termsof its shoot-through duty ratio for each qZS-HBI module, asFig. 1(b) shows. A proportional ( ) regulator is employed inthe inductor current loop to improve the dynamic response,and a PI regulator of the dc-link voltage loop ensures the dc-linkpeak voltage tracking the reference.Finally, the independent modulation signals and shoot-

through duty ratios of the qZS-CMI, ,are combined into the proposed multilevel SVM to achieve thedesired purposes.

III. SYSTEM MODELING AND CONTROL

Fig. 2 shows block diagram of the proposed grid-tie con-trol with the system model for the qZS-CMI based PV powersystem. The details will be explained as follows.

A. Grid-Tie Current Loop

The th qZS-HBI module has following dynamic:

(4)

where is the current of qZS inductor , is the th PVarray’s current, and is the capacitance of PV array terminalcapacitor.The qZS-CMI based grid-tie PV system has

(5)

where is the grid voltage, is the grid-injected current,is the filter inductance, and is its parasitic resistance. Thetransfer function of the grid-injected current can be

(6)

A PR regulator [13]

(7)

is employed to enforce the actual grid-injected current to trackthe desired reference.With a grid voltage feed forward control, the th qZS-HBI

module has the modulation signal

(8)

with

(9)

where is the regulated modulation signal from the separatevoltage control of the th module, as Fig. 2 shows.From (8) and (9), we have

(10)

At the dc-link peak voltage balance control, all dc-link peakvoltages are the same. The qZS-HBI modules have the sametransfer function, and we assume

(11)

Using (6)–(11), the grid-injected current will be

(12)

Then, the current loop of Fig. 2 is simplified to Fig. 3, and theopen-loop transfer function can be obtained as

(13)

With the compensation of the PR regulator, the transfer func-tion becomes

(14)


Fig. 3. Simplified block diagram of the grid-current closed loop.

Consequently, the closed-loop transfer function of grid-tie cur-rent control can be obtained in (15), shown at the bottom of thepage.

B. PV Voltage Loop

From (4), we have

(16)

In addition, the output power of each qZS-HBI moduleequals to its input power in the nonshoot-through state, the thqZS-HBI module has the power equation

(17)

where is the average current of inductor in non-shoot-through state. Using (1), can be solved as

(18)

In the shoot-through state, the average current of inductorcan be expressed as

(19)

Combining (18) and (19), the average current of inductoris

(20)

Then, the block diagrams of total and separate PV voltage loopscan be obtained in Figs. 4 and 5.

Fig. 4. Block diagram of total PV voltage loop.

Fig. 5. Block diagram of separate PV voltage loop.

If is considered as disturbance, with (20) and Fig. 4, thetransfer function of the total PV array voltage loop is given by(21), shown at the bottom of the page, where the coefficientsand are

(22)

The PI regulator is applied to trackthe total reference voltage coming fromMPPT algorithm. Thus,the open-loop transfer function of total PV voltage loop aftercompensation can be obtained by

(23)

where

(15)

(21)


Fig. 6. Block diagram of the th module’s dc-link peak voltage control.

The closed-loop transfer function is

(24)

where and.

Similarly, from Fig. 5, the transfer function of the thqZS-HBI module’s PV voltage loop, , is

(25)

which is compensated by PI regulator. Then, the resultant open-loop transfer function of the

th qZS-HBI module’s PV voltage loop becomes

(26)Also, the closed-loop transfer function is obtained as

(27)

C. DC-Link Voltage Control

The independent dc-link peak voltage control based on the in-ductor- current and the capacitor- voltage is performed foreach qZS-HBI module, as Fig. 1(b) shows. From [14], the thqZS-HBI module’s transfer functions from the shoot-throughduty ratio to the dc-link peak voltage, , and from theshoot-through duty ratio to the inductorcurrent, ,can be obtained, respectively.With the employed proportional regulator at the coefficient

for the inductor current loop, as the block diagram ofFig. 6 shows, the closed-loop transfer function of inductorcurrent can be obtained by

(28)

A PI regulator with the transfer function ofis cascaded to the inductor current loop for

controlling the dc-link peak voltage, as shown in Fig. 6. There-fore, the th qZS-HBI module’s dc-link peak voltage controlhas the open-loop transfer function

(29)

Fig. 7. Proposed multilevel SVM for the single-phase qZS-CMI. (a) Switchingpattern of one qZS-HBI module. (b) Synthetization of voltage vectors for theqZS-CMI.

and the closed-loop transfer function

(30)

IV. PROPOSED MULTILEVEL SVM FOR QZS-CMI

As the qZS network is embedded to the HBI module, theSVM for each qZS-HBI can be achieved by modifying the SVMtechnique for the traditional single-phase inverter [15]. Usingthe first qZS-HBI module of Fig. 1 as an example, the voltagevector reference is created through the two vectors and, by

(31)

where and is the carrier frequency; the time in-terval is the duration of active vectors, and is the durationof traditional zero voltage space vectors. Thus, the switchingtimes for the left and right bridge legs in traditional HBI are

. However, the shoot-throughstates are required for the independent qZS-HBI module.For this purpose, a delay of the switching times for upper

switches or a lead of the switching times for lower switchesare employed at the transition moments, as Fig. 7(a) shows.During each control cycle, the total time of shoot-throughzero state is equally divided into four parts. The time intervalsof and remain un-changed; andare the modified times to generate the shoot-through states;and are the switching control signals for the upper switches,

and are that for the lower switches, .In this way, the shoot-through states are distributed into theqZS-HBI module without additional switching actions, losses,and resources.To generate the step-like ac output voltage waveform from

the qZS-CMI, a phase difference, in which is thenumber of reference voltage vectors in each cycle, is employedbetween any two adjacent voltage vectors, as Fig. 7(b) shows.The total voltage vector is composed of reference vectors

from the qZS-HBI modules.

V. CONTROL PARAMETER DESIGN

The prototype specifications of qZS-CMI based PV powersystem are shown in Table I. For the grid-connected current


TABLE IPROTOTYPE SPECIFICATIONS

TABLE IICONTROL PARAMETERS

Fig. 8. Bode diagrams of and .

loop, the PR regulator parameters are designed to get a fast dy-namic and zero-steady state error at the grid frequency [13].The fast dynamic response and stable steady-state performanceare taken into account to design the control parameters for totalPV voltage control loop, separate PV voltage control loop, anddc-link voltage control loop. The design results are shown inTable II, and all of the Bode plots are shown in Figs. 8–10.Fig. 8 shows the Bode plots of the grid-tie current loop

transfer functions and , which are before andafter compensation, respectively. The symbol is the cornerfrequency of , which equals from (6); is theresonant frequency of the PR regulator, i.e., grid frequency of314 rad/s. After compensation, provides a large gaininside its bandpass region, making the crossover frequency al-most tenfold the corner frequency . Thus, the grid-connectedfast response is greatly enhanced without loss of stability,which can be obtained from the bode diagram of closed-looptransfer function .

Fig. 9. Bode diagrams of (a) and ; and (b) and.

Fig. 10. Bode diagrams of (a) and and (b)and .

Fig. 9(a) shows the Bode plots of total PV voltage controlloop transfer functions and , which cor-respond to before and after compensation, respectively. The39.1-dB gain margin and 90.5 phase margin show an un-stable . By using the zero-pole assignment of ,the compensated transfer function presents stablefeatures, which is also verified from the Bode plots of the closed-loop transfer function .Similarly, the Bode plots of separate PV voltage control are

shown in Fig. 9(b). From Fig. 9(b) and (25), we know thatthe is not stable. Compensated by the PI regulator

, an 87.5 phase margin is shown in . Theclosed-loop transfer function also confirms its stablefeature.Fig. 10 shows the Bode plots of transfer functions for each

module’s dc-link peak voltage control loop. When using a pro-portional gain , the inductor current shows a fasterresponse without loss of the stability, as shown in Fig. 10(a).From Fig. 10(b), the dc-link peak voltage closed-loop’s stabilityis greatly improved by decreasing the crossover frequency. Asa result, the closed-loop transfer function presents afast and robust characteristic.

VI. SIMULATION AND EXPERIMENTAL VERIFICATIONS

A seven-level qZS-CMI for grid-connected PV power systemis prototyped. Two Agilent E4360A Solar Array Simulators(SAS) are used to emulate the electrical behavior of PV arrays.Each SAS has two channel outputs, and each channel is withmaximum 120-V maximum power point (MPP) voltage ( )and 5-A MPP current ( ). Simulation and experimentalresults are shown in Figs. 11–15.


Fig. 11. Simulation results of qZS-CMI at different PV array voltages.

A. DC-Link Voltage Balance Test

The different PV array voltages are performed for the threeqZS-HBI modules. The second module’s PV voltage is setto 70 V and the others are at 90 V. A 50- resistor is used as acload in this test. All of the voltages in experimental results are100 V/div.From (1), the 136-V dc-link voltage of qZS-HBI module is

required to support the 230-V grid. Fig. 11 shows the simula-tion results, where the second module’s dc-link peak voltage isboosted to the same voltage value when compared with othermodules, but with a longer shoot-through time interval. Also,the qZS-CMI outputs the seven-level voltage with equal voltagestep from one level to another level.Fig. 12 shows the experimental results. We can find that the

same qZS-CMI output voltages and currents are achieved inFig. 11 (or Fig. 12), which is derived from the designed dc-linkpeak voltage control.

B. Grid-Tie Investigation

The qZS-CMI is connected to the grid in order to test theproposed grid-tie control. Fig. 13 shows the PV array’s power-voltage characteristics. The measured PV array voltage and cur-rent of each module are used to calculate the actual PV powerand the MPPT algorithm searches for the PV voltage referenceat the MPP, which is refreshed every 0.05 s. Here, the perturba-tion and observation (P&O)MPPT strategy is applied in consid-ering the excellent tracking efficiency and easy implementation[16].At first, the three modules are all working at 900 W/m , and

all of the initial voltage references of MPPT algorithms aregiven at 105 V from Fig. 13. The second module’s irradiationdecreases to 700W/m from 1 to 2 s in simulation. Fig. 14 showsthe simulation results. In the experiments, the same test condi-tions of irradiation and temperature can be implemented by set-ting the curves of Agilent SAS. Fig. 15 shows the experimentalresults.Fig. 14(a) shows the total PV voltage (sum of three PV panel

voltages) and reference, PV panel voltages and references ofmodules 2 and 3, respectively.Fig. 14(b) is the enlarged detail of Fig. 14(a). It can be seen

that the excellent tracking performance is achieved during 0–1 s;

Fig. 12. Experimental results of qZS-CMI at different PV array voltages.(a) Two modules’ PV array voltages and dc-link voltages. (b) Two PV arrayvoltages, seven-level output voltage, and load current.

Fig. 13. PV array power–voltage characteristic.

even though the second module’s PV irradiation changes after1 s, the still tracks the reference very well after a very shorttransient.Fig. 14(c) and (d) shows that the grid-injected current is

exactly in phase with the grid voltage even at the irradiationchanging moment. The solar irradiation does not affect theseven-level staircase output voltage of qZS-CMI, but the lowerirradiation makes the grid-injected current reduced.The identical experimental results are shown in Fig. 15. As

in Fig. 15(a), the lower solar irradiation reduces the second


Fig. 14. Simulation results at the grid-tie case. (a), (b) For PV voltages atMPPT. (c), (d) For qZS-CMI output voltage, grid voltage, and current.

module’s PV panel current, the first and third modules’ PVpanel currents are not changed due to their constant irradiations.

Fig. 15. Experimental results at the grid-tie case. (a) Three PV panel currents.(b) Second module’s PV panel voltage, qZS-CMI output voltage, grid voltage,and the grid-injected current. (c) Results zoomed in when the second module’sPV irradiation changes from 900 to 700 W/m .

The second module’s low irradiation causes the system powerreduced, so the grid-injected current decreases, as Fig. 15(c)shows. No matter the solar irradiation changes or not, theqZS-CMI always outputs consistent voltage, which verifiesthe voltage balance ability. In simulation and experiments, theirradiation change may be derived from the shading of cloudor other objects. Figs. 14 and 15 validate the proposed controlmethods.

VII. CONCLUSION

This paper proposed a control method for qZS-CMI basedsingle-phase grid-tie PV system. The grid-injected power wasfulfilled at unity power factor, all qZS-HBI modules separatelyachieved their own maximum power points tracking even if


some modules’ PV panels had different conditions. Moreover,the independent dc-link voltage closed-loop control ensured allqZS-HBI modules have the balanced voltage, which providedthe high quality output voltage waveform to the grid. The con-trol parameters were well designed to ensure system stabilityand fast response. A multilevel SVM integrating with shoot-through states was proposed to synthesize the staircase voltagewaveform of the single-phase qZS-CMI.The simulation and experiment were carried out on the

seven-level qZS-CMI prototype. The qZS-CMI based grid-tiePV system was tested. The simulation and experimental resultsverified the proposed qZS-CMI based grid-tie PV power systemand the proposed control method.In principle, the proposed system can work with the weak

grid, even though this paper did not address this topic. In futurework, we will focus on the application to the weak grid, and thedetailed analysis and experimental results will be disclosed inthe next paper.

REFERENCES[1] J. Chavarria, D. Biel, F. Guinjoan, C.Meza, and J. J. Negroni, “Energy-

balance control of PV cascaded multilevel grid-connected invertersunder level-shifted and phase-shifted PWMs,” IEEE Trans. Ind. Elec-tron., vol. 60, no. 1, pp. 98–111, Jan. 2013.

[2] F. Filho, H. Z. Maia, T. H. A. Mateus, B. Ozpineci, L. M. Tolbert,and J. O. P. Pinto, “Adaptive selective harmonic minimization basedon ANNs for cascade multilevel inverters with varying DC sources,”IEEE Trans. Ind. Electron., vol. 60, no. 5, pp. 1955–1962, May 2013.

[3] S. Kouro, C. Fuentes, M. Perez, and J. Rodriguez, “Single DC-link cas-caded H-bridge multilevel multistring photovoltaic energy conversionsystem with inherent balanced operation,” in Proc. IECON 38th Annu.Conf. IEEE Ind. Electron. Soc., Oct. 25–28, 2012, pp. 4998–5005.

[4] S. Rivera, S. Kouro, B. Wu, J. I. Leon, J. Rodriguez, and L. G. Fran-quelo, “Cascaded H-bridge multilevel converter multistring topologyfor large scale photovoltaic systems,” in Proc. IEEE Int. Symp. Ind.Electron., Jun. 27–30, 2011, pp. 1837–1844.

[5] L. Liu, H. Li, Y. Zhao, X. He, and Z. J. Shen, “1 MHz cascadedZ-source inverters for scalable grid-interactive photovoltaic (PV)applications using GaN device,” in Proc. IEEE Energy Conv. Congr.Expo., Sep. 17–22, 2011, pp. 2738–2745.

[6] B. Ge, “Energy Stored Cascade Multilevel Photovoltaic Grid-TiePower Generation System,” China Patent ZL201010234877.0, Jul.2010, in Chinese.

[7] Y. Zhou, L. Liu, andH. Li, “AHigh-performance photovoltaic module-integrated converter (MIC) based on cascaded quasi-Z-source inverters(qZSI) using eGaN FETs,” IEEE Trans. Power Electron., vol. 28, no.6, pp. 2727–2738, Jun. 2013.

[8] D. Sun, B. Ge, F. Z. Peng, H. Abu-Rub, D. Bi, and Y. liu, “A newgrid-connected PV system based on cascaded H-bridge quasi-Z sourceinverter,” in Proc. IEEE Int. Symp. Ind. Electron., May 28–31, 2012,pp. 951–956.

[9] H. Abu-Rub, A.. Igbal, Sk. Moin Ahmed, F. Z. Penz, Y. Li, and B. Ge,“Quasi-Z-source inverter-based photovoltaic generation system withmaximum power tracking control using ANFIS,” IEEE Trans. Sustain.Energy, vol. 4, no. 1, pp. 11–20, Jan. 2013.

[10] B. Ge, H. Abu-Rub, F. Peng, Q. Lei, A. de Almeida, F. Ferreira, D. Sun,and Y. Liu, “An energy stored quasi-Z-source inverter for applicationto photovoltaic power system,” IEEE Trans. Ind. Electron., vol. 60, no.10, pp. 4468–4481, Oct. 2013.

[11] H. Abu-Rub, M. Malinowski, and K. Al-Haddad, Power Electronicsfor Renewable Energy Systems, Transportation and Industrial Appli-cations. Hoboken, NJ, USA: Wiley, 2014.

[12] Y. A. Mahmoud, W. Xiao, and H. H. Zeineldin, “A parameterizationapproach for enhancing PV model accuracy,” IEEE Trans. Ind. Elec-tron., vol. 60, no. 2, pp. 5708–5716, Dec. 2013.

[13] D. N. Zmood and D. G. Holmes, “Stationary frame current regulationof PWM inverters with zero steady-state error,” IEEE Trans. PowerElectron., vol. 18, no. 3, pp. 814–822, May 2003.

[14] Y. Liu, B. Ge, F. Z. Peng, H. Abu-Rub, A. T. de Almeida, and F. J. T.E. Ferreira, “Quasi-Z-Source inverter based PMSG wind power gener-ation system,” in Proc. IEEE Energy Conv. Congr. Expo., Sep. 17–22,2011, pp. 291–297.

[15] J. I. Leon, S. Vazquez, J. A. Sanchez, R. Portillo, L. G. Franquelo, J.M. Carrasco, and E. Dominguez, “Conventional space-vector modula-tion techniques versus the single-phase modulator for multilevel con-verters,” IEEE Trans. Ind. Electron., vol. 57, no. 7, pp. 2473–2482, Jul.2010.

[16] M. A. G. de Brito, L. Galotto, L. P. Sampaio, G. de Azevedo e Melo,and C. A. Canesin, “Evaluation of the main MPPT techniques for pho-tovoltaic applications,” IEEE Trans. Ind. Electron., vol. 60, no. 3, pp.1156–1167, Mar. 2013.

Yushan Liu (S’12) received the B.Sc. degree inautomation from the Beijing Institute of Technology,Beijing, China, in 2008. She is currently workingtoward the Ph.D. degree in electrical engineeringat the School of Electrical Engineering, BeijingJiaotong University, Beijing.She is also currently a Research Assistant with the

Department of Electrical and Computer Engineering,Texas A&M University at Qatar, Doha, Qatar. Herresearch interests include modeling and control ofZ-source inverters, cascade multilevel inverters, PV

power generation, and battery energy storage.

Baoming Ge (M’11) received the Ph.D. degree inelectrical engineering from Zhejiang University,Hangzhou, China, in 2000.He was a Postdoctoral Researcher with the Depart-

ment of Electrical Engineering, Tsinghua University,Beijing, China, from 2000 to 2002, was a VisitingScholar with the Department of Electrical and Com-puter Engineering, University of Coimbra, Coimbra,Portugal, from 2004 to 2005, and was a Visiting Pro-fessor with the Department of Electrical and Com-puter Engineering (ECE), Michigan State University

(MSU), East Lansing, MI, USA, from 2007 to 2008. He is currently with theECE of MSU as well as a Professor with the School of Electrical Engineering,Beijing Jiaotong University, Beijing, which he joined in 2002. His research in-terests include renewable energy power generation, electrical machines and con-trol, power electronics systems, and control theories and applications.

Haitham Abu-Rub (M’99–SM’07) received theM.Sc. degree in electrical engineering from GdyniaMarine Academy, Gdynia, Poland, in 1990, andthe Ph.D. degree from the Gdansk University ofTechnology, Gdansk, Poland, in 1995.For eight years, he was with Birzeit University,

Birzeit, Palestine, where he was first an AssistantProfessor and then an Associate Professor and wasthe Chairman of the Electrical Engineering Depart-ment for four years. He is currently a Full Professorwith the Department of Electrical and Computer

Engineering, Texas A&M University at Qatar, Doha, Qatar. His main researchinterests are the electrical machine drives and power electronics.Dr. Abu-Rub was a recipient of many international prestigious awards, such

as the American Fulbright Scholarship (at Texas A&MUniversity, College Sta-tion), the German Alexander von Humboldt Fellowship (at Wuppertal Univer-sity, Wuppertal, Germany), the German DAAD Scholarship (at Ruhr UniversityBochum, Bochum, Germany), and the British Royal Society Scholarship (at theUniversity of Southampton, Southampton, U.K.).

Fang Z. Peng, photograph and biography not available at the time ofpublication.

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