• Journal of Power Electronics
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• v.16 no.1
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• pp.340-350
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• 2016

A cascaded hybrid multilevel inverter including a reconfiguration technique for low voltage dc distribution applications is proposed in this paper. A PWM generation fault detection and reconfiguration paradigm after an inverter cell fault are developed by using only a single-chip controller. The proposed PWM technique is also modified to reduce switching losses. In addition, the proposed topology can reduce the number of required power switches compared to the conventional cascaded multilevel inverter. The proposed technique is validated by using a 3-kVA prototype. The switching losses of the proposed multilevel inverter are also investigated. The experimental results show that the proposed hybrid inverter can improve system efficiency, reliability and cost effectiveness. The efficiency of proposed system is 97.45% under the tested conditions. The proposed hybrid inverter topology is a promising method for low voltage dc distribution and can be applied for the multiple loads which are required in a data center or telecommunication building.

• Journal of Power Electronics
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• v.13 no.2
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• pp.223-231
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• 2013

A modular three-phase multilevel inverter especially suitable for electrical drive applications has been previously presented. This topology is based on series connection of power cells in which each cell comprised of two inverter legs in series. In this paper, in order to generate the maximum number of voltage levels with reduced number of switches, three algorithms are proposed for determination of the magnitudes of dc voltage sources. In addition, a new hybrid multilevel inverter is proposed that is composed of series connection of the previously presented multilevel inverter and some H-bridges. The proposed topology has been compared with some other presented multilevel inverters. The performance of the proposed multilevel inverter has been verified by simulation and experimental results of a single-phase 39-level multilevel inverter.

• Journal of Power Electronics
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• v.10 no.4
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• pp.365-373
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• 2010

This paper proposes a hybrid single carrier sinusoidal modulation suitable for multiphase multilevel inverters. Multiphase multilevel inverters are controlled by hybrid modulation to provide multiphase variable voltage and a variable frequency supply. The proposed modulation combines the benefits of fundamental frequency modulation and single carrier sinusoidal modulation (SC-SPWM) strategies. The main characteristics of hybrid modulation are a reduction in switching losses and improved harmonic performance. The proposed algorithm can be applied to cascaded multilevel inverter topologies. It has low computational complexity and it is suitable for hardware implementations. SC-SPWM and its base modulation design are implemented on a TMS320F2407 digital signal processor (DSP). A Complex Programmable Logic Device realizes the hybrid PWM algorithm and it is integrated with a DSP processor for hybrid SC-SPWM generation. The feasibility of this hybrid modulation is verified by spectral analysis, power loss analysis, simulation and experimental results.

• Journal of Power Electronics
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• v.14 no.3
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• pp.507-518
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• 2014

This paper presents a new cascaded asymmetrical single phase multilevel converter with a lower number of power semiconductor switches and isolated DC sources. Therefore, the number of power electronic devices, converter losses, size, and cost are reduced. The proposed multilevel converter topology consists of two H-bridges connected in cascaded configuration. One H-bridge operates at a high frequency (high frequency inverter) and is capable of developing a two level output while the other H-bridge operates at the fundamental frequency (low frequency inverter) and is capable of developing a multilevel output. The addition of each power electronic switch to the low frequency inverter increases the number of levels by four. This paper also introduces a hybrid switching algorithm which uses very simple arithmetic and logical operations. The simplified hybrid switching algorithm is generalized for any number of levels. The proposed simplified switching algorithm is developed using a TMS320F2812 DSP board. The operation and performance of the proposed multilevel converter are verified by simulations using MATLAB/SIMULINK and experimental results.

• Journal of Electrical Engineering and Technology
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• v.10 no.2
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• pp.574-585
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• 2015

This paper aims to improve the performance of conventional direct torque control (DTC) drives proposed by Takahashi by extending the idea for 5-level inverter. Hybrid cascaded H-bridge topology is used to achieve inverter voltage vector composed of 5-level of voltage. Although DTC is very popular for its simplicity but it suffers from some disadvantages like- high torque ripple and uncontrollable switching frequency. To compensate these shortcomings conventional DTC strategy is modified for five levels voltage source inverter (VSI). Multilevel hysteresis controller for both flux and torque is used. Optimal voltage vector selection from precise lookup table utilizing 12 sector, 9 torque level and 4 flux level is proposed to improve DTC performance. These voltage references are produced utilizing a hybrid cascaded H-bridge multilevel inverter, where inverter each phase can be realized using multiple dc source. Fuel cells, car batteries or ultra-capacitor are normally the choice of required dc source. Simulation results shows that the DTC drive performance is considerably improved in terms of lower torque and flux ripple and less THD. These have been experimentally evaluated and compared with the basic DTC developed by Takahashi.

• Journal of Electrical Engineering and Technology
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• v.13 no.1
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• pp.270-279
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• 2018

This paper elucidates a hysteresis current controller for enhancing the performance of static synchronous compensator (STATCOM) using cascaded H-bridge multilevel inverter. Due to the rising power demand and growing conventional generation costs a new alternative in renewable energy source is gaining popularity and recognition. A five level single phase cascaded multilevel inverter with two separated dc sources, which is energized by photovoltaic - wind hybrid energy source. The voltages across the each dc source is balanced and standardized by the proposed hysteresis current controller. The performance of STATCOM is analyzed by connecting with grid connected system, under the steady state & dynamic state. To reduce the Total Harmonic Distortion (THD) and to improve the output voltage, closed loop hysteresis current control is achieved using PLL and PI controller. The performance of the proposed system is scrutinized through various simulation results using matlab/simulink and hardware results are also verified with simulation results.

• Journal of Power Electronics
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• v.10 no.3
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• pp.277-284
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• 2010

This paper presents a novel hybrid carrier based space vector modulation for cascaded multilevel inverters. The proposed technique inherits the properties of carrier based space vector modulation and the fundamental frequency modulation strategy. The main characteristic of this modulation are the reduction of power loss, and improved harmonic performance. The carrier based space vector modulation algorithm is implemented with a TMS320F2407 digital signal processor. A Xilinx Complex Programmable Logic Device is used to develop the hybrid PWM control algorithm and it is integrated with a digital signal processor for hybrid carrier based space vector PWM generation. The inverter offers less weighted total harmonic distortion and it operates with equal electrostatic and electromagnetic stress among the power devices. The feasibility of the proposed technique is verified by spectral analysis, simulation, and experimental results.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.18 no.2
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• pp.68-74
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• 2004

This paper presents a novel hybrid multilevel inverter using DC-Link voltage combination in order to improve the waveshape of output voltage and reduce harmonics. The proposed multilevel inverter can generate an 11-level output voltage. It employs three H-bridge cell, which consists of single phase full-bridge inverter module. Among them, two modules are used for level generation, and one module performs PWM switching. Nine levels are synthesised by the level inverter, and two levels are added to output by the PWM inverter. As a result, it generates an 11-level. The operational principles are explained in depth, and the validity of the proposed system is verified through the PSpice simulation and experimental results based on a prototype.

• Journal of Electrical Engineering and Technology
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• v.10 no.4
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• pp.1610-1620
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• 2015

A major problem in conventional multilevel inverter is that an increase in power semiconductor switches causes an increase in cost and switching losses of the inverter. The multicarrier strategy adopted for the multilevel inverters has become more popular due to reduced cost, lower harmonic distortion, and higher voltage capability than the conventional switching strategy applied to inverters. Various topologies and modulation strategies have been reported for utility and drive applications. Level shifted based pulse width modulation techniques are proposed to investigate the performance of the multilevel inverter. The proposed work focuses on reducing the utilized switches so that the cost and the switching losses of the inverter do not go up and the consistent efficiency could be achieved. This paper presents the detailed analysis of these topologies. The analysis is based on the number of switches, DC sources, output level, maximum voltage, and the efficiency. As an illustration, single phase cascaded multilevel inverter topologies are simulated using MATLAB/SIMULINK and the experimental results demonstrate the viability of these inverters.

• Proceedings of the KIPE Conference
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• 2003.07a
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• pp.23-26
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• 2003

This paper presents a novel hybrid type multilevel inverter in order to improve the waveshape of output voltage. The proposed multilevel inverter is consist of two full-bridge modules for level creation and one full-bridge module for PWM operation. The generated levels are total 11-level: 9-level by the level inverter and 2-level by the PWM inverter. The operational principles and analysis are explained and validity of the proposed system is verified through the experimental results using a prototype.