solar inverters
MULTILEVEL INVERTER WITH SMART CONTROL TECHNIQUE FOR SOLAR PV-FUEL CELL HYBRID SYSTEM APPLICATIONS
- Dr Umashankar S, Aryadip Sen, Abhishek Soni, Bhimanapati Lakshmi Anisha, Bandaru Jayasree School of Electrical Engineering, VIT University, Vellore, Tamil Nadu
INTRODUCTION
M
ultilevel inverters have been adopted from the past years, as they made the easy energy conversion. If the output voltage of the inverter is more than two levels then it is termed as multilevel inverter. As the levels increases there will be reduction in the output current harmonic distortion, unnecessary energy loss and improvement in the system efficiency as well as reliability. Many topologies are introduced in the field of multilevel inverters due to wide research and its applications in different fields. This article illustrates the comparison of two different topologies which are industry oriented i.e. Neutral Point Piloted (NPP) and Active Neutral Point Piloted (ANPC). It reveals about the controlling techniques employed in these systems. Alternate Phase Opposition Disposition (APOD) and Phase shifting PWM prominent techniques are used. It gives a brief idea of the neutral point potential balancing technique, loss calculation and output current distortion.
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BLOCK DIAGRAM
DC SOURCE
3-LEVEL NPP / ACTIVE NPC INVERTER
INDUCTION DRIVE LOAD
CONTROLLING STRATEGY
PWM GENERATOR
Fig 1: Block diagram of Inverter with Controlling
CONTROLLING TECHNIQUES : I) PHASE SHIFTING PWM METHOD Phase shifting PWM technique is generally used for the pulse generation. The basic principle of this technique is to compare a line frequency sinusoidal reference signal with a high frequency two phase shifted triangular carrier wave form in order to get the required pulses for the switches. For every time instant when the carrier wave form is greater than reference wave form the pulse is set (1) otherwise reset (0).
Fig 2 : Waveform of Phase shifting PWM Method
EQ
June-July 2015
41Â