Three-Phase Five-Level Grid Synchronized PV Inverter with MPPT for Micro-Grid Application


This paper develops an interesting converter for three phase grid interface for photovoltaic panels. Here a new topology having least number of power semiconductor switches in the five level category is used. The converter consists of three basic sections viz. the photovoltaic source, a two phase inverter and a Scott-T transformer that converts the two-phase inverter output to three phases and connects to the grid. The control system is in the d-q reference frame which provides fast dynamic control response. A maximum power point tracking mechanism (MPPT) is used to generate the direct axis current reference in order to inject the maximum available power into the grid for any insolation. The converter has been designed and developed for 1kW. This is also experimentally validated.


  1. Current referenced control
  2. Maximum Power Point
  3. Sine pulse width modulation
  4. Scott-T Transformer
  5. Isolated Grid Tied Inverter



The paper presents a reduced switched method for generating a five level voltage output from a PV system. The whole converter system consists of three stages, the PV system with MPPT control, the 16 switch two-phase converter and finally isolation stage using Scott-T transformer. The converter pumping the current towards the grid is controlled by taking the PV MPP output current and providing it as Id reference for the inverter. This Id reference current controls the Id value of the inverter current control loop. Two-phase 16 switch inverter topology consist of high frequency and low frequency stages. High frequency stage will have a maximum switching stress voltage of Vdd=2 and similarly low frequency unfolding stage will have a maximum stress voltage of Vdd. The inverter has a self-balanced dc link capacitor pairs without any complex control schemes. Proper simulation analysis for the five level inverter sourced from a PV which in turn fed to grid has done which conforms its application on grid tied applications. Hardware implementation for two-phase level is also made and waveforms were verified comparing with the simulation. Further section of hardware is to be done in future in order to detail verification and making a complete prototype model for analysis.


[1] B. Satish Naik , L. Umanand, K. Gopakumar and B. Subba Reddy, ”A New Two-Phase Five-Level Converter for Three-Phase Isolated Grid-Tied Systems With Inherent Capacitor Balancing and Reduced Component Count” IEEE Journal of Emerging and Selected Topics in Power Electronics., VOL. 6, NO. 3,pp 1325-1335 Sep. 2018

[2] Gautam A. Raiker, L. Umanand and B. Subba Reddy, ”Perturb and Observe with Momentum Term applied to Current Referenced Boost Converter for PV Interface” 2018 IEEE International Conference on Power Electronics, Drives and Energy Systems (PEDES)

[3] Gautam A. Raiker , Subba Reddy B., Praveen C. Ramamurthy, L. Umanand, Abines S. G. and Shama G. Vasisht ”Solar PV interface to Grid-Tie Inverter with Current Referenced Boost Converter” 2018 IEEE 13th International Conference on Industrial and Information Systems(ICIIS)

[4] J. Rodrguez, J.-S. Lai, and F. Z. Peng, Multilevel inverters: A survey of topologies, controls, and applications, IEEE Trans. Ind. Electron., vol. 49, no. 4, pp. 724738, Aug. 2002

[5] A. Nabae, I. Takahashi, and H. Akagi, A new neutral-point-clamped PWM inverter, IEEE Trans. Ind. Appl., vol. IA-17, no. 5, pp. 518523, Sep. 1981

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