In the recent years the multilevel inverters were widely discussed topic for researchers. Because of few merits of having good power quality. Basically inverter is a converter, which is capable in converting the DC power into AC power at desired level. The two level output, zero or positive or negative V dc can be obtained by voltage source inverter(VSI). The multilevel inverter is capable to produce sinusoidal output voltage and to reduce Total Harmonic Distortion at desired voltage level. As we increase the level of voltage, the output power quality gets improved, i.e. THD gets reduced. This paper proposes the implementation and analysis of cascaded multilevel inverter with reduce THD. The implemented Cascaded H-bridge Multilevel Inverter topology is a practical topology; it provides the generalized path to increase the level of multilevel inverter as we want. In the represented model of eleven level single phase Cascaded H-bridge Multilevel Inverter has been designed using IGBT in order to generate the different output voltage levels at proper intervals, the conduction angle of IGBTs have been controlled by varying the pulse width of getting signals. Simulation models is developed in MATLAB-SIMULINK of eleven levels inverters and THD analysis is performed.

An Efficient Technique to reduce Total Harmonics Distortion in Cascaded H- Bridge Multilevel Inverter

This paper presents an improved hysteresis current control method for five level T-type inverter. The proposed method is based on four hysteresis levels and performed to generate switching signals of fundamental transistors in T-type inverter. By using generated signals through hysteresis controller, bidirectional switch in T-type inverter is triggered through the logical way. The system is detailed in analytical expression and exhibited to generate five voltage levels at the output of inverter. The improved technique is based on an error signal between the output current and the reference value. Therefore, the proposed modulation technique achieves the following output current at the desired value and ensures high-efficiency conversion ratio at the output. In order to show the validity of the proposed method, the controller is compared with conventional sinusoidal pulse width modulated T-type inverter. In performance results, it is obvious that the proposed method provides a lower total harmonic distortion in comparison with conventional method.

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Performance Analysis of T-type Inverter Based on Improved Hysteresis Current Controller

This paper deals with a pulsed power supply system combining flywheel energy storage system (FESS) and a modular multilevel cascade converter (MMCC) for power compensation in performing rapid excitation of highly inductive and pulsed heavy loads. The FESS system consists of an induction motor with a flywheel to store kinetic energy. Parallelly connected capacitors cause self-excitation phenomena in an induction motor, and it works as an induction generator. Furthermore, the induction generator generates more than twice of electric power of its rated value for a short time. We can apply the proposed FESS to particle accelerators for physics experiments or medical use, and plasma shape and position control in pulsed nuclear fusion devices that require pulsed highpower. In addition, the coils in these applications that generate magnetic fields have large inductances. In plasma control and repetitive operation applications, it is necessary to change current rapidly. We can realize high-speed current control by using the proposed MMCC that can output a voltage higher than the input voltage. By combining the FESS and MMCC, a power supply may be realized with the ability to implement rapid current control while compensating for large power consumption and without significant load disturbance on the power grid.

Combination of Flywheel Energy Storage System and Boosting Modular Multilevel Cascade Converter

Received Jun 1, 2020 Revised Aug 1, 2020 Accepted Aug 17, 2020 This paper proposes a nearest level control method based modulation scheme for a 9-level symmetrical transistor clamped H-bridge (TCHB) inverter. The topology has gained increasing research focus due to its advantages in obtaining high-quality output while using a reduced number of electronic components. The device count for getting a 9-level output voltage is 10 switches compared to 16 switches being used in a conventional 9-level cascaded H-bridge (CHB) inverter. The significant contribution of the research is the development of the nearest level control (NLC) method that operates at the fundamental frequency, thus reducing switching losses, and able to reduce harmonic content significantly. The reduced harmonic content can lessen the power quality problem. The NLC modulation scheme shows that the overall THD is reduced without the need for filtration. The 50 values of harmonic content will be counted that follows the IEEE Standard 519. MATLAB/Simulink based simulations and experimental results obtained from the laboratory prototype of a single-phase TCHB inverter feeding an R load validate the theoretical analyses and effectiveness of the proposed modulation scheme.

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Voltage harmonics reduction in single phase 9-level transistor clamped H-bridge inverter using nearest level control method

This paper presents a transformer-based multilevel inverter (MLI) integrated with a photovoltaic system. It has lower number of components than a conventional MLI, thereby reducing the overall cost. Here, a nine level MLI is designed with only eight switches, whereas 16 switches are required for achieving a nine-level voltage in a conventional transformer-less MLI. The design has multiple H-bridges and a single transformer fed from a single dc source. The transformer helps in achieving the process of intermediate voltage regulation. A pulse width modulation (PWM) scheme is used to obtain the gate pulses. Another advantage of the design is that, only one dc source is used for the MLI. Also, several switching redundancies are possible for various voltage levels of the MLI. This decreases the switching losses. The photovoltaic integrated system is verified using MATLAB simulations and a basic hardware of the MLI is also made.

Photovoltaic Integration of a Transformer-based Multi Level Inverter With Lesser Components

Double reference single carrier modulation technique is a new technique employed for generating pulses for multilevel inverters. This paper presents a simulation of a transistor clamped H-bridge multilevel inverter using double reference single carrier modulation technique. Using the modulation technique, output voltage, output current and voltage stress across the switches of the transistor clamped multilevel inverter is obtained. The total harmonic distortion obtained for different values of the modulation index is presented. Further, the paper aims to perform a comparison of a transistor clamped H-Bridge multilevel inverter with a conventional cascaded H-Bridge multilevel inverter. The comparison is done with respect to complexity of the circuit topologies and total harmonic distortion obtained with both the multilevel inverters. Results are obtained using simulations done in MATLAB Simulink environment.

M Anzari

Papers

Simulation of a transistor clamped H-bridge multilevel inverter and its comparison with a conventional H-bridge multilevel inverter