Harmonic Analysis of Three Level Diode Clamped Inverter

2017

At present, multilevel inverters are extensively used in industries for high power and high voltage applications. Inverter can be broadly classified as two level inverter and multi level inverters. The multi level started with the three level converters. Minimum harmonic distortion is one of advantage of multilevel inverter. This paper deals with hardware design and analysis of three level diode clamped IGBT based inverter. The elementary concept of a multilevel converter is to achieve high power by using a series of a power semiconductor switches with lower voltage D.C source. The output voltage waveform of a multi-level inverter is comprises of the number of levels of voltages, typically obtained from capacitor voltage sources. In this paper, single phase diode clamp multilevel inverter topology is analyzed by employing SPWM technique which controls the switching operation with the help of Microcontroller programming and also the results are shown for the same. Index Terms-Diode C...

At present, multilevel inverters are extensively used in industries for high power and high voltage applications. Two categories into which inverters can be broadly classified are two level inverters and multilevel inverters. The multilevel began with the three level converters. One advantage that multilevel inverters have compared to two level inverters is minimum harmonic distortion. This paper deals with study and analysis of three level diode clamped MOSFET based inverters and its applications in industries. The main purpose of the paper is to study and implement 3 level diode clamped inverter using MOSFET's, the PWM signals used to switch these MOSFET's has been generated using PWM IC HEF4752VP. However, the output voltage is smoother with a three level converter, these results in smaller harmonics, but on the other hand it has more components and it is little complex to control in hardware. 

The power electronics device which converts DC power to AC power at required output voltage and frequency level is known as inverter. Multilevel inverter is to synthesize a near sinusoidal voltage from several levels of dc voltages. In order to maintain th e different voltage levels at appropriate intervals, the conduction time intervals of MOSFETS have been maintained by controlling the pulse width of gating pulses. In this paper single phase to three phase power conversion using pwm technique. The simulation is carried out in Matlab/Simulink environment which demonstrate the feasibility of proposed scheme. Over the years, three-phase motors, more than single phase motors have been the main consideration in industries due to certain parameters such as; efficiency, torque ripples and power factor. In rural areas, in order to operate machine tools and rolling mills as well as in low power industrial application for robotics, where a three phase utility may not be available, high-performance converters are typically used to run the three-phase motor drives. Low losses and cost effectiveness are the very important properties for these converters various single-phase to three-phase converters have been proposed with at least 6 switches. An alternative for the reduction of losses in these converters is that the number of po wer switches is reduced. Many components-minimized structures are proposed in literatures.[1] Pulse Width Modulated (PWM) inverter systems are used in a wide variety of applications as a front-end power-conditioning unit in electric drives, uninterruptible power supplies, high voltage DC transmission, Active power filters, reactive power compensators in power systems, Electric vehicles, Alternate energy systems and Industrial processes. The inverters realize dc-to-ac power conversion andin the most commonly used voltage source inverter configuration. The dc-input voltage can be obtained from a diode rectifier or from another dc source such as a battery.[2 3 4] A typical voltage source PWM inverter system consists of rectifier, DC-link, PWM inverter along with associated control circuit and the load. Most modern voltage source inverters are controlled using a wide variety of pulse width modulation schemes, to obtain output ac voltages of the desired magnitude and frequency shaped as closely as possible to a s ince wave. Analysis of PWM inverter system is required to determine the input-output characteristics for an application specific design, which is used in the development and implementation of the appropr iate control algorithm.[56] Three different topologies have been proposed for multilevel inverters: diode-clamped (neutral-clamped) capacitor-clamped (flying capacitors) and cascaded multi cell with separate dc sources. In addition, several modulation and control strategies have been developed or adopted for multilevel inverters including the following: multilevel sinusoidal pulse width modulation (PWM), multilevel selective harmonic elimination, and space-vector modulation (SVM).[7 8] The most attractive features of multilevel inverters are as follows. 1) They can generate output voltages with extremely low distortion and lower dv/dt. 2) They draw input current with very low distortion. 3) They generate smaller common-mode (CM) voltage, thus reducing the stress in the motor bearings. In addition, using sophisticated modulation methods, CM voltages can be eliminated. 4) They can operate with a lower switching frequency. The diode-clamp method can be applied to higher level converters As the number of levels increases, the synthesized output waveform adds more steps, produ cing a staircase wave which approaches the sinusoidal wave with minimum harmonic distortion. Ultimately, a zero harmonic distortion of the output wave can be obtained by an infinite number of levels. More levels also mean higher voltages can be spanned by series devices without device voltage sharing problems.[9 10] Unfortunately, the number of the achievable voltage levels is quite limited not only d ue to voltage unbalance problems but also due to voltage clamping requirement, circuit layout, and packaging constraints. The simulation is carried out in Matlab/Simulink environment which demonstrate the feasibility of proposed scheme.

Multilevel inverter is an important alternative technique in high power, medium voltage power control. Multilevel inverter topology is classified in to diode clamped multilevel inverter (DCMLI), flying capacitors multilevel inverter, cascaded inverter with separate dc source. This project presents diode clamped multilevel inverter with sinusoidal pulse width modulation (SPWM) framework. The carrier based SPWM technique is developed to facilitate its implementation in diode clamped multilevel inverter. Diode clamped multilevel inverter using MOSFET as switching device is used in this particular project. Furthermore, in this study reduction of harmonics has been stressed on using diode clamped multilevel inverters. It also states the adverse effects of Total Harmonic Distortion (THD) on generation and transmission equipments. It also explains about Common Mode Voltage and its effects in brief. Multilevel Inverters have been designed, modeled and simulated and the output results have been depicted in the form of waveforms, THD analysis modules using MATLAB SIMULINK and the results are systematically tabulated.

—The power electronics device which converts DC power to AC power at required output voltage and frequency level is known as inverter. The voltage source inverters produce an output voltage or a current with levels either 0 or +ve or-ve V dc. They are known as two-level inverters. Multilevel inverter is to synthesize a near sinusoidal voltage from several levels of dc voltages. Multilevel inverter has advantage like minimum harmonic distortion. Multi-level inverters are emerging as the new breed of power converter options for high power applications. They typically synthesize the staircase voltage waveform (from several dc sources) which has reduced harmonic content. Multi-level inverters have many attractive features, high voltage capability, reduced common mode voltages near sinusoidal outputs, low dv/dt, and smaller or even no output filter; sometimes no transformer is required at the input side, called the transformer-less solution, making them suitable for high power applications In this paper a 5-level Diode clamped multilevel inverter is developed by IGBTS using Simulink. Gating signals for these IGBTS have been generated by designing comparators. In order to maintain the different voltage levels at appropriate intervals, the conduction time intervals of IGBT have been maintained by controlling the pulse width of gating pulses[6] (by varying the reference signals magnitude of the comparator). The simulation results for 5-level and THD for the output have been identified by MATLAB/SIMULINK.

This paper present three phase three level diode clamped multi level inverter. The control technique used here is sine pulse width modulation. The inverter can reduce the harmonic components compared with that of traditional full-bridge inverter under the condition of identical supply DC voltage and switching frequency. Here this paper presents a operational principles and switching functions are analyzed. The proposed inverter improves the dynamic performances Inverter is simulated using MATLAB/SIMULINK FFT analysis has been done. Proto type hardware is developed in laboratory and simulation results are compared with experimental results. Voltage to frequency control in open loop for three phase induction motor has also been done.

2010

Switching losses become significant in high voltage, high power applications. Multilevel inverters are used to reduce the harmonics and to achieve high voltage, high power capability but switching losses are increased due to increased device count. Switching losses can be reduced by employing space vector based PWM techniques or sinusoidal PWM based techniques. In this paper, a carrier based closed loop control technique has been developed to reduce the switching losses based on insertion of "no switching" duration within each half cycle of fundamental wave. It effectively reduced the switching losses of three-level inverter without any complex mathematical expressions as involved in space vector based techniques. An improvement of about 5% in efficiency for a switching frequency of 5 kHz is observed with proposed technique over conventional SPWM technique based on Efficiency Improvement Factor (EIF).

COMPLEXITY INTERNATIONAL JOURNAL, 2021

The relevance of multilevel inverters has been increased since last few decades. These new Types of inverters are suitable for high voltage and high power application. These inverters are able to synthesize waveforms with better harmonic spectrum and with less Total Harmonic Distortion (THD).Numerous topologies have been introduced and widely studied for utility of Non-conventional sources and also for drive applications. This report presents information about several multilevel inverter topologies, such as the Neutral Point Clamped Inverter and the Cascaded Multilevel Inverter. From among these some multilevel inverters will also be compared with a new topology with reduced number of switches. The THD values will also be compared modulation method used will be Sine PWM and its operation is confirmed with simulation results obtained from a Simulink model realization in MATLAB environment.

Energy Procedia, 2016

In general, Multi-level converter has been utilized widely in many applications, especially in renewable energy aspects. This is because of the associations in high power, medium switch voltage and lower output total harmonics distortion. In this article, the multi-level converter was constructed as a 2 kW output power of the 3 phase 3 level diode clamped grid connected inverter. The proposed multi-level inverter uses a carrier based space vector pulse width modulation scheme in order to produces the desired output voltage. The scheme is the modulation of three identical reference signals, which is 120 phase shifted to each other comparing to a 10 kHz triangular signal. These reference signals comprise of some harmonics in order to generate a space vector PWM signal for switches in the inverter. A Phase Lock Loop (PLL) is utilized together with the controller in order to phase and frequency locking between the voltage at the point of common connection (PCC) and voltage at the grid system. After the proposed inverter connected to the grid system, it can be injected the inverter current into grid system by using the appropriated PI (proportional-integrator) controller within the control scheme. However, L-C low-pass filter is also utilized at the inverter output for reducing harmonic contents. It results to reducing the output harmonic contents. In which, the value of THDv at PCC is less than 5 %.

2011

This paper presents simulation focus in a single phase diode clamped multilevel inverter topology also known as Neutral Point Clamped. Circuit will construct and simulate by using PSIM software and the solution is based on series connection of three to ninelevel diode clamped inverters modules. IGBT devices are used almost exclusively in this power range. The more level can be produce, it does will be much better for the application. It is because the value of THD also will decrease once the levels of the multilevel inverter increase. The simulation result shows the total harmonic distortion (THD) for three, five, seven and nine level of diode clamped topologies.