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Birla Institute of Technology Mesra Jaipur.pptx

  1. 1. DEPT: OF ELECTRICAL ENGINEERING Multilevel Inverter Topology With Reduced Switch Count Presentation by: Ayush Jindal Shashank Bhadouria Ruhi Jain Anjali Garg Project Guide: Dr. Prashant Singh Rathod Dr. Deepak Verma Dr. Aprajita Panday
  2. 2. Abstract Nowadays multilevel inverters are a very attractive solution for medium-voltage high power conversion applications; they convert DC power to AC power at required output voltage and frequency level. Three-phase Multilevel Inverter (MLI) are used in many medium and high-power applications such as motor drives and grid connected systems. There are numerous Pulse Width Modulation (PWM) techniques for MLIs.This technique is recommended to improve the performance of inverter and to eliminate the filtering requirements. The topology used here is that of H bridge inverter. In this, separate DC sources are used for each H bridge. If the value of DC voltage is same in all the bridges, then it can simply be called as a cascaded multilevel inverter. In case of different DC voltage being used in different H bridges, then it is called a Hybrid multilevel inverter.
  3. 3. INTRODUCTION ❖ Inverters convert DC voltage to variable magnitude, variable frequency AC voltage. ❖ Ideally, purely sinusoidal output voltage.Practically not possible. ❖ PWM Techniques makes the task of extracting sinusoidal voltage from output of inverters easier.
  4. 4. Drawbacks of two-level VSIs for MV Drives ● High dv/dt in the inverter output voltage – as high as 10,000V/µs ● Motor harmonic losses This can be solved by adding properly tuned LC filter. It has some disadvantages ● Increased manufacturing cost ● Fundamental voltage drop ● Circulating current between the filter and DC circuit
  5. 5. Why Multilevel Inverter Topology With Reduced Switch Count ? In order to overcome the problem of distortion in the output voltage waveform caused due to the presence of harmonics, this project proposes the modelling an Inverter with three dc voltage sources and ten switches to synthesize 15 levels across the load using MATLAB/SIMULINK. The objectives of the work area: ● To study and simulate a three phase 15 level Voltage Source Inverter. Comparison in performance of two-Level inverters. ● To understand and implement Pulse Width Modulation for minimization of filtering requirements
  6. 6. Multilevel Voltage Source Inverter Multi-level inverters are the preferred choice in industry for the application in High voltage and High power application Advantages of Multi-level inverters ● Higher voltage can be generated using the devices of lower rating. ● Increased number of voltage levels produce better voltage waveforms and reduced THD. ● Switching frequency can be reduced for the PWM operation.
  7. 7. The three basic and popular MLI topologies used in commercial application since last few decades:- 1. Neutral Point Clamped (NPC) 2. Flying Capacitor (FC) 3. Cascade H-Bridge (CHB)
  8. 8. STRUCTURE OF OUR WORK
  9. 9. SWITCHING SCHEME
  10. 10. SIMULATION MODEL
  11. 11. Pulse Width Modulation: For Positive Cycle
  12. 12. Pulse Width Modulation: For Negative Cycle
  13. 13. For Instance : PWM-S1
  14. 14. OUTPUT
  15. 15. ADVANTAGES: ➢ Better waveform quality of output voltage (more sinusoidal). ➢ Reduced dV/dt, leading to reduction in EMI. ➢ Multilevel converters produce smaller CM voltage; therefore, the stress in the bearings of a motor connected to a multilevel motor drive can be reduced. ➢ Lower voltage rating devices can be used. DISADVANTAGE: ➢ More number of power semiconductor switches are needed. ➢ Some configurations need more than one isolated DC supply.
  16. 16. RESULT AND CONCLUSION Two level Inverter Five level Inverter Fifteen level Inverter THD was around 72.86%. THD is around 35.41%. THD is around 4.71% Applicable for low power ratings. For higher power ratings Application in high power ratings Less number of switches required Requirement of more number of switches Requirement of circuit components increases with increase in levels of the inverter Efficiency is around 50% Efficiency is around 83.75% Efficiency is around 98.19%
  17. 17. CONCLUSION AND DISCUSSION ➢ As the number of level increases, THD decreases and active power increases. ➢ The output waveforms of the voltage and load current are also approximated sine wave. ➢ Increasing the number of voltage levels in the inverter without requiring higher rating on individual devices can increase power rating. ➢ Earlier simulated Three-phase Fifteen level Inverter results has been compared to three phase five level inverter and it is found that the total harmonic distortion has been reduced by 31.1%.
  18. 18. FUTURE SCOPE ● The THD can be further reduced by increasing the number of inverter levels. ● More efficient control Techniques such as Space Vector modulation can be implemented. ● Suitable filter design for further improvement of output voltage. ● Implementation of hardware circuits .

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