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Research paper thumbnail of Comparative Study of Three level and Five level Inverter

This paper analyses and compares the different cascaded H-Bridge multilevel inverter used for dc ... more This paper analyses and compares the different cascaded H-Bridge multilevel inverter used for dc to ac power conversion. The simulation of multilevel inverters is done in MATLAB/SIMULINK software.The activepoweroutput,reactive power output and Total Harmonic Distortion (THD) in output voltage produced in 3-level and 5-level inverters are obtained and compared.It was observed that THD in 5-level inverteris less as compared to 3-level inverter & THD in 7-level inverter is less as compared to 3-level and 5-level inverter. KEYWORDS: Cascaded H-Bridge Multilevel Inverter,Three level inverter.Five level inverter,Comparison. I.INTRODUCTION The use of renewable energy sources is increasing to supply the increasing demand of electricity due to urbanisation. Solar energy produces dc power which needs to be converted into ac for further applications. Conversion of dc power to ac is done using cascaded H bridge multilevel inverter with less THD. The high power cascaded H bridge multilevel inverter should be analysed with respect to its output active power, reactive power and THD in output voltage. This study will help the design engineer in selecting the appropriate multilevel inverter for required application. Multilevel inverters are classified as current source inverter and voltage source inverter. In case of multilevel current source inverter, it was observed that if there is short circuit in the circuit, the fault current will be very high further damaging the other equipment's connected in the circuit. Therefore multilevel voltage source inverters are more commonly used [3].Multilevel voltage source inverters are classified into three main categories as (i) cascaded H-bridge multilevel inverter, (ii) Neutral point clamped multilevel inverter and (iii) Flying capacitor multilevel inverter. Cascaded H bridge multilevel inverter is more commonly used because it gives high output voltage, reliability, power levels and simplicity of control. II.CASCADED H-BRIDGE MULTILEVEL INVERTER The cascaded H-Bridge multilevel inverter are the most advanced and important method of power electronic converters that analyses output voltage with number of dc sources as inputs.As compared to neutral point clamped multilevel inverter and flying capacitor multilevel inverter,the cascaded H-Bridge multilevel inverters requires less number of components and it reaches high quality output voltage which is close to sinewave. By increasing the number of output levels the total harmonic distortion in output voltage can be reduced.In cascaded H-Bridge multilevel inverterrequired AC output voltage is obtain by synthesizing number of DC sources.The number of H-Bridge units with different DC sources is connected in series or cascade to produce cascaded H-Bridge multilevel inverter[4]. III.SINGLE PHASE 3-LEVEL CASCADED H-BRIDGE MULTILEVEL INVERTER Fig 1 shows Single phase Three level Cascaded H-Bridge inverter consisting of single isolated DCsource,four IGBT switches& R-L load. The result of output voltage waveform of three level multilevel inverter is shown in fig 3.consists of three levels 0,+Vdc,-Vdc[1].

Research paper thumbnail of Comparative Study of Three level and Five level Inverter

This paper analyses and compares the different cascaded H-Bridge multilevel inverter used for dc ... more This paper analyses and compares the different cascaded H-Bridge multilevel inverter used for dc to ac power conversion. The simulation of multilevel inverters is done in MATLAB/SIMULINK software.The activepoweroutput,reactive power output and Total Harmonic Distortion (THD) in output voltage produced in 3-level and 5-level inverters are obtained and compared.It was observed that THD in 5-level inverteris less as compared to 3-level inverter & THD in 7-level inverter is less as compared to 3-level and 5-level inverter. KEYWORDS: Cascaded H-Bridge Multilevel Inverter,Three level inverter.Five level inverter,Comparison. I.INTRODUCTION The use of renewable energy sources is increasing to supply the increasing demand of electricity due to urbanisation. Solar energy produces dc power which needs to be converted into ac for further applications. Conversion of dc power to ac is done using cascaded H bridge multilevel inverter with less THD. The high power cascaded H bridge multilevel inverter should be analysed with respect to its output active power, reactive power and THD in output voltage. This study will help the design engineer in selecting the appropriate multilevel inverter for required application. Multilevel inverters are classified as current source inverter and voltage source inverter. In case of multilevel current source inverter, it was observed that if there is short circuit in the circuit, the fault current will be very high further damaging the other equipment's connected in the circuit. Therefore multilevel voltage source inverters are more commonly used [3].Multilevel voltage source inverters are classified into three main categories as (i) cascaded H-bridge multilevel inverter, (ii) Neutral point clamped multilevel inverter and (iii) Flying capacitor multilevel inverter. Cascaded H bridge multilevel inverter is more commonly used because it gives high output voltage, reliability, power levels and simplicity of control. II.CASCADED H-BRIDGE MULTILEVEL INVERTER The cascaded H-Bridge multilevel inverter are the most advanced and important method of power electronic converters that analyses output voltage with number of dc sources as inputs.As compared to neutral point clamped multilevel inverter and flying capacitor multilevel inverter,the cascaded H-Bridge multilevel inverters requires less number of components and it reaches high quality output voltage which is close to sinewave. By increasing the number of output levels the total harmonic distortion in output voltage can be reduced.In cascaded H-Bridge multilevel inverterrequired AC output voltage is obtain by synthesizing number of DC sources.The number of H-Bridge units with different DC sources is connected in series or cascade to produce cascaded H-Bridge multilevel inverter[4]. III.SINGLE PHASE 3-LEVEL CASCADED H-BRIDGE MULTILEVEL INVERTER Fig 1 shows Single phase Three level Cascaded H-Bridge inverter consisting of single isolated DCsource,four IGBT switches& R-L load. The result of output voltage waveform of three level multilevel inverter is shown in fig 3.consists of three levels 0,+Vdc,-Vdc[1].

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