APsystems MICROINVERTER Installation Training - FULL VERSION

APsystems YC500 microinverter installation video training series: Complete Series (Parts 1-12) In A Single Video

Electronic Engineering -Circuit theory 1 -Professor Kim, Myung-Sik- Kumoh National Institute of Technology-SOUTH KOREA

Circuit theory 1 is the first major subject of electronic engineering students, and it is the basis of all courses.

POWER ELECTRONICS CIRCUITS- KIM YOUNG-ANYANG UNIVERSITY

POWER ELECTRONICS CIRCUITS- KIM YOUNG-ANYANG UNIVERSITY

LEARN ABOUT FLYBACK CONVERTER IN ISOLATED DC-DC CONVERTER WHERE TRANSFORMER ARE USED.

Modulation Techniques for Leakage Current Reduction in Transformer-less Photovoltaic Inverter Systems- Arsalan Ansari -Department of Electronic Systems Engineering Hanyang University Graduate School

Modulation Techniques for Leakage Current Reduction in Transformer-less Photovoltaic Inverter Systems 
Author : Arsalan Ansari
Thesis Supervisor: Prof. Hee-Jun Kim 
 Thesis for the degree of [Doctor of Philosophy] 
 Department of Electronic Systems Engineering Hanyang University Graduate School

 Abstract 
Energy constitutes a fundamental part in human lives. The well-being and prosperity of the globe is directly linked to energy growth. Overcoming the demand of energy is a key challenge to be solved. Keeping up with pace of energy demand, it requires unprecedented levels of investment and the purist of all economic energy sources. The energy needs are growing and conventional resources are not suitable to compete with the global requirements of energy. Therefore, the trend is to use renewable energies to compensate with the energy requirements. The renewable energies such as photovoltaic (PV) modules, fuel cells and wind turbines are of particular interest due to their tremendous advantages over conventional sources of energy. PV energy is one of the most widely used among all the other forms of renewable energies. This is due to the fact that the PV systems are relatively smaller in size, perform noiseless operation, require simple installation and the possibility to install PV systems closer to the user. The PV energy can either be used independently or can be connected to the utility grid. To connect the PV energy to the grid, the energy conversion device is necessary to convert dc voltage to the ac voltage (inverter). Previ- ously line transformer or a high frequency transformer is used with inverter to provide isolation between PV system and grid. The transformer in the system, however decreases the e ciency, increases the cost and weight and makes the system complex. Therefore, transformer-less inverters are mostly preferred in PV systems due to their high e ciency, low cost, small weight and less complexity. In this thesis a three level transformer-less inverter is used with grid in- teraction. Avoiding a transformer in such systems results in leakage current due to the direct connection between PV panel and utility grid. The high values of the leakage current may be problematic and can cause harmonics and losses in the PV system, electromagnetic interference and even electri- cal safety problems. The major causes of leakage current in transformer-less grid connected PV system are the parasitic capacitance of the PV panel and varying common mode (CM) voltage appearing across the parasitic capaci- tance of PV panel. The leakage current in transformer-less PV system can be reduced either by keeping the CM voltage constant or reducing the am- plitude and frequency of CM voltage. There are many solutions to reduce leakage current within international standards. They include the modi - cation of the inverter topology, by active or passive damping of LCL lter and by improved modulation methods. The modulation methods are most widely used in the industry because there is no need of topological modi ca- tion or extra hardware which increases the cost of the PV system. Various modulation methods to reduce the leakage current in the literature are dis- cussed brie y in this thesis. In most cases space vector based pulse width modulation (SVPWM) methods are used to solve leakage current problems, because three level in- verter has an inherent capability to produce the constant CM voltage by using particular space vectors and thereby eliminating the leakage current in the system. A new simpli ed SVPWM strategy is proposed which is easy to implement as compare to conventional three level SVPWM. The pro- posed SVPWM reduces the leakage current and maintains it within limits as enforced by international standards. The main features of the proposed SVPWM technique are; less computational burden, small leakage current and low THD of phase currents. Detailed theoretical analysis of the pro- posed modulation technique are validated by simulations and experimental demonstration shows the e ectiveness of the proposed SVPWM. A carrier based PWM is also proposed in this thesis to reduce the leak- age current of three level transformer-less PV inverter. The carrier based PWM is very simple since it requires only one carrier to synthesize the output voltage of three level inverter. Due to its carrier based nature this PWM strategy can easily be operated in over-modulation region. Apart from leakage current reduction the proposed PWM is capable of balancing the neutral point (NP) voltage of the three level inverter. Simulation and experiments are carried out for the proposed carrier based PWM to verify the e ectiveness for the leakage current reduction and NP voltage balancing. Finally the proposed PWM techniques are compared with the modula- tion techniques presented in the literature. It is found that the proposed PWM techniques not only suppress the leakage current within allowable limits as described by the international standards but have better spectral performance.
LINK THESIS
https://www.mediafire.com/file/y3c4jhrdvs68bdj/Modulation_Techniques_for_Leakage_Current_Reduction.pdf/file

Prácticas de electrónica Por Paul B. Zbar, Albert Paul Malvino, Michael A. Mille

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