Five-level inverter with dual reference modulation technique for grid-connected PV system

This paper presents a single-phase five-level grid-connected PV inverter with a novel dual reference modulation technique. Two reference signals identical to each other with an offset equivalent to the amplitude of the triangular carrier signal were used to generate PWM signals. The inverter consists of a full-bridge inverter and an auxiliary circuit comprising four diodes and a switch. The inverter produces output voltage in five levels: zero, +1/2Vdc, Vdc, −1/2Vdc and −Vdc. A digital PI current control algorithm is implemented in DSP TMS320F2812 to keep the current injected into the grid sinusoidal and to have high dynamic performance with low THD. The validity of the proposed inverter is verified through simulation and implemented in a prototype. The experimental results are compared with conventional single-phase three-level grid-connected PWM inverter in terms of THD.

[1]  G. Sciutto,et al.  A new multilevel PWM method: a theoretical analysis , 1990, 21st Annual IEEE Conference on Power Electronics Specialists.

[2]  Jeyraj Selvaraj,et al.  Multilevel Inverter For Grid-Connected PV System Employing Digital PI Controller , 2009, IEEE Transactions on Industrial Electronics.

[3]  Samir Kouro,et al.  Reduced Switching-Frequency-Modulation Algorithm for High-Power Multilevel Inverters , 2007, IEEE Transactions on Industrial Electronics.

[4]  Vassilios G. Agelidis,et al.  A multilevel PWM inverter topology for photovoltaic applications , 1997, ISIE '97 Proceeding of the IEEE International Symposium on Industrial Electronics.

[5]  Muhammad H. Rashid,et al.  Power Electronics: Circuits, Devices and Applications , 1993 .

[6]  Vassilios G. Agelidis,et al.  Analysis of multicarrier PWM methods for a single-phase five level inverter , 2001, 2001 IEEE 32nd Annual Power Electronics Specialists Conference (IEEE Cat. No.01CH37230).

[7]  N. S. Choi,et al.  A general circuit topology of multilevel inverter , 1991, PESC '91 Record 22nd Annual IEEE Power Electronics Specialists Conference.

[8]  M. Vitelli,et al.  Optimizing duty-cycle perturbation of P&O MPPT technique , 2004, 2004 IEEE 35th Annual Power Electronics Specialists Conference (IEEE Cat. No.04CH37551).

[9]  Saad Mekhilef,et al.  Implementation of three-phase grid connected inverter for photovoltaic solar power generation system , 2002, Proceedings. International Conference on Power System Technology.

[10]  L.A.C. Lopes,et al.  An improved perturbation and observation maximum power point tracking algorithm for PV arrays , 2004, 2004 IEEE 35th Annual Power Electronics Specialists Conference (IEEE Cat. No.04CH37551).

[11]  P.L. Chapman,et al.  Comparison of Photovoltaic Array Maximum Power Point Tracking Techniques , 2007, IEEE Transactions on Energy Conversion.

[12]  Man Hyung Lee,et al.  A new single-phase five-level PWM inverter employing a deadbeat control scheme , 2003 .

[13]  L.M. Tolbert,et al.  Novel multilevel inverter carrier-based PWM methods , 1998, Conference Record of 1998 IEEE Industry Applications Conference. Thirty-Third IAS Annual Meeting (Cat. No.98CH36242).