Design and Implementation of Three-phase Three level NPC Inverter

[Audio] hello everyone, I am arun kumar from tkr college of engineering and technology , today im here to present my paper Design and Implementation of Three-phase Three level NPC Inverter.

[Audio] Topics to be covered : Abstract Introduction Topology of 3-level npc inverter Control Scheme Simulation Results Conclusion.

[Audio] AbstractThe three-level NPC PWM inverter is a type of multilevel inverter that provides a higher quality of output wave form compared to traditional two-level inverter. It is a type of power electronic converter that is used in renewable energy such as wind turbine and PV system. It convert DC power source into AC power source. It has also have capable of handling high power levels and provides better efficiency compared to other inverter topologies. Since, inverter uses PWM technique to control the switching power of semiconductor devices. Keywords: multilevel inverter, neutral point clamped inverter, three level inverter, spwm technique..

[Audio] Introduction In comparison to other inverters that have been researched and used in the past, NPC inverters are one of the most significant multilevel inverter structures. Low volts is needed to power the devices using this kind of inverter, and the output voltage needs to have minimal harmonic content.The topological structure cannot be expanded because of the inherent neutral voltage balance issue.[1][12]The primary approach for a three-level NPC inverter uses SVPWM and PWM to manage the average value of NP currents at zero in a switching instance (PWM)[2]. Nabae, Takahashi, and Akagi created the neutral point converter in 1981; it was essentially a 3-level diode-clamped inverter. The multi-level inverter is more capable and effective power applications nowadays [3]. This inverter is utilised in high voltage, high power efficiency applications with a wide variety of machine speeds [4]. Three-level NPC inverter benefits include: maximising efficiency at switching times.At the appropriate voltage level, the capacitors can recharge once more. Due to the sharing of all phases to a single set of DC links, the inverter's capacitance can be kept to a minimum.[5].

[Audio] Since new approaches for controlling the switches in inverters were introduced. Pulse width modulation, for example (PWM). This method has the benefit of having a cheap device switching cost. The most common used for the PWM technique is sinusoidal PWM technique (SPWM). The NPC multi level inverter can be operated as 3 modes operations. i.e. Dipolar, Unipolar and Partial dipolar.As a result, the dc link voltage in an NPC 3-level inverter can be divided into two equal capacitors. The fluctuation in NP voltage is the 3-level inverter's serious issue.In this study, an SPWM project was constructed that offers an NPC multi-level inverter with voltage balance control and waveform for switching between levels of three and five Only the measurement of load current and DC link voltage is required for this project. The load performance is not high flow because the balancing voltage strategy is based on adding the appropriate diagonals/angles to the provided order of the voltage..

[Audio] Control SchemeThe most commonly used modulation scheme for an NPC inverter is the SPWM technique. The basic concept of SPWM involves comparing a reference sinusoidal wave form with high frequency carrier wave form. The magnitude and frequency of the carrier wave form are typically much higher than the reference wave form. In an NPC inverter, the DC voltage is split into multiple levels using capacitors and diodes, resulting in several voltage levels that can be used to generate a quasi-sinusoidal output wave form. The SPWM technique is then applied to each level of the NPC inverter to generate the appropriate switching signals for the power electronics. The basic concept of SPWM involves differential a reference sinusoidal waveform with a high- frequency carrier waveform. The amplitude and frequency of the carrier waveform are typically much higher than the reference waveform. The resulting modulated waveform has the same frequency as the reference waveform and a variable amplitude determined by the width of the pulses in the carrier waveform..

[Audio] Overall system of SPWM technique To implement SPWM in an NPC inverter, the reference sinusoidal waveform is typically generator using a microcontroller or DSP. The carrier waveform is generator using a high- frequency oscillator or a PWM generator. The reference waveform is then compared with the carrier waveform to generator the modulated waveform. The resulting modulated waveform is then used to generator the switching signals for the power electronics The rate of the carrier waveform controls the exchanging rate of the power electronics, while the width of the pulses in the carrier waveform dictates the amplitude of the output voltage.

[Audio] Figure shows the simulation wave form of SPWM technique X-axis indicate time(sec) and Y-axis indicate SPWM technique. Overall, the SPWM technique is a widely used method for generating quasi-sinusoidal waveforms in power electronics. When applied to NPC inverters, it allows for precise control of the output voltage while minimizing harmonic distortion and improving efficiency.

[Audio] Simulation Results Figure(5) shows the simulation wave form of 3-phase line voltage of individual R,Y,B. X-axis indicate the time(sec) and Y-axis indicate the VRY,VYB,VBR..

[Audio] Figure(6) shows the simulation wave form of 3-phase line voltage of combined RYB. X-axis indicate the time(sec) and Y-axis indicate the 3-phase line voltage..

[Audio] Figure(7) shows the imitation wave form of 1-phase line voltage of R or Y or B. X-axis indicate the time(sec) and Y-axis indicate the line voltage..

[Audio] Figure(8) shows the simulation wave form of 3-phase phase voltage of individual R,Y,B. X-axis indicate the time(sec) and Y-axis indicate the R-phase, Y-phase, B-phase..

[Audio] Figure shows the switching sequence of SPWM technique of S1,S2,S3. X-axis indicate time(sec) and Y-axis indicate S1,S2,S3..

[Audio] V.Conclusion In conclusion, the 3- level NPC inverter with PWM technique is highly efficient and effective method for providing high quality AC power. It offers numerous benefits over traditional two level inverters and has become increasingly popular in a range of applications. Its ability to provide precise control over the output waveform makes it an excellent choice for many different type of power systems..

[Audio] THANK YOU !!. Thank You.