Nho Van Nguyen

• Ho Chi Minh City University of Technology

This paper proposes a novel virtual vector space vector pulse width modulation (SVPWM) method called Average Zero common mode voltage (AZCMV) PWM to mitigate low-frequency CMV in four-level neutral point clamped (4L-NPC) inverters. Due to the absence of zero CMV vectors in the space vector diagram (SVD) of 4L inverter, the proposed SVPWM method int...

This article presents a hybrid asymmetric reduced-CMV pulse-width modulation (PWM) scheme, namely HRCMV-ASYM for the three-level Neutral-Point- Clamped converter (3L-NPC) to further reduce the harmonic distortion of the previously proposed scheme (RCMV1) while still achieving the same reduced CMV magnitude and zero average CMV. The proposed hybrid...

Due to the capacitive nature of Common-mode impedance, high-frequency Common-mode voltage due to high switching frequency leads to an increase in RMS leakage current, which, in turn, causes higher power loss, Electromagnetic Interferences, and deteriorated harmonic distortion in the three-level Neutral-Point-Clamped converter. Recently-proposed pul...

High-frequency Common-mode voltage (CMV) excites undesirable bearing current and motor ground leakage current due to capacitive nature of Common-mode (CM) impedance. This high-frequency CMV can be effectively eliminated with Zero-CMV Pulse-width modulation (ZCMV-PWM) schemes at the expense of inferior output harmonic distortion and high switching l...

Extra switching generates additional switching power loss, thus leading to the reduction of the efficiency of a system. Therefore, the article aims to reduce the switching power loss incurred owing to the extra switching in the transition of two carriers in the previously proposed strategy (RCMV1), which features reduced common-mode voltage and imp...

Nowadays, Cascade H-bridge (CHB) multi-level inverters (MLI) have many applications in the fields of electric drive control, high-power energy control, medium-voltage power grids, and popularization in the conversion of renewable energy power. In order to improve the quality of MLI to meet today's needs while reducing costs, it is necessary to have...

This paper proposes a novel 3-phase asymmetric 3-level T-type NPC inverter and studies its PWM performance using a virtual space vector pulse width modulation control strategy. Firstly, the mathematical model and characteristics of this economical topology are described. Then, a virtual space vector approach is proposed to build a space vector diag...

In this paper, a model predictive control for an asymmetric T-type NPC 3-level inverter is presented. The mathematical model and characteristics of the reduced switching topology are described. An improvement for the predicted strategy with the pre-selected candidate vectors is proposed. The simulation and experimental results are provided and show...

High-frequency components of common-mode voltage (CMV) induce the shaft voltage and bearing current, which lead to premature failures in motors. In addition, due to non-zero average CMV, the low-frequency components of CMV, particularly the third-order harmonic component, have been reported to cause difficulties in common-mode filter design. Furthe...

This paper studies and compare the performances of different control strategies of 3-phase active rectifier under different load and frequency conditions. There are three main control approaches to be investigated such as: Voltage Oriented Control (VOC), Direct Power Control (DPC) and Model Predictive Control (MPC). The traditional method VOC has b...

Multilevel voltage source inverters (VSIs) have been used for several decades thanks to their advantages compared with traditional two level VSI. Among various types of multilevel configuration, the T-type neutral-point-clamped VSI (3L TNPC VSI or 333-type VSI) has gained the attention in recent years. Due to the unique structure, the 333-type VSI...

This article presents a carrier-based pulsewidth modulation (PWM) strategy to reduce the common-mode voltage (CMV) with output harmonic distortion minimization for three-level neutral-point-clamped (NPC) inverters. The proposed method is first presented for three-level NPC inverters, and then, generalized for odd n -level inverters including NPC...

This paper presents a pulse-width modulation strategy to eliminate the common mode voltage (CMV) with reduced CMV spikes in multilevel inverters since a high CMV magnitude and its fast variations dv/dt result in bearing failure of motors, overvoltage at motor terminals, and electromagnetic interference (EMI). The proposed method only utilizes the z...

This paper presents a novel Stator Current based Model Reference Adaptive System (SC_MRAS) speed observer for high-performance Six Phases Induction Motor (SPIM) drives using linear neural network. The article aim is intended to improve performance of an SC_MRAS observer, which were presented in the literature. In this proposed scheme, the measured...

In this paper, a Stator Current Model Reference Adaptive System (SC_MRAS) based estimator using neural network for sensorless controlled Six Phase Induction Motor (SPIM) drive is presented. For this scheme the measured stator current components are used as the reference model of the MRAS estimator to avoid the use of a pure integrator and reduce in...

Bai bao giới thiệu phương phap mới về điều khiển dựa theo kỹ thuật điều chế độ rộng xung – PWM (Pulse Width Modulation) cho bộ nghịch lưu ap đa bậc dựa tren cơ sở ham offset them vao nhằm lam giảm điện ap common-mode(common-mode voltage) ở ngo ra. Bắt đầu từ bộ nghịch lưu đa bậc kiểu nối tầng kinh điển, sử dụng hai thanh phần điện ap la base voltag...

In this paper, a novel switching voltage modeling and offset-based Pulse Width Modulation (PWM) scheme for multilevel inverters with unbalanced dc sources is presented. The switching voltage model under DC-voltage imbalance will be formulated in general form for both Neutral point Clamped and cascaded multilevel inverter topologies. An analysis of...

This paper introduces a novel pulse width modulation (PWM) technique to eliminate common-mode voltage in odd-multilevel inverters using the three zero common-mode vectors principles. Similarly, as in conventional PWM for multilevel inverters, this PWM can be properly depicted in an active two-level voltage inverter. With the help of two standardize...

This paper presents a novel switching voltage model and an offset-based pulse width modulation (PWM) scheme for multilevel inverters with unbalanced DC sources. The switching voltage model under a DC voltage imbalance will be formulated in general form for multilevel neutral-point-clamped topologies. Analysis of the reference switching voltages fro...

This paper presents a carrier-based modulation method for indirect matrix converters to reduce the switching losses. Based on discontinuous pulse width modulation technique, the number of switchings in one cycle period is reduced. Along with an algorithm to select a suitable offset voltage for generating the modulation signals of the inverter stage...

In this paper, a novel offset-based two-level pulse width modulation (PWM) scheme for a multilevel inverter with unbalanced dc sources is presented. The offset voltage is introduced as an indispensable variable in the control model for a multilevel voltage source inverter. An expression for the inverter parameters in abc coordinates can enable the...

This paper presented a control method for balancing capacitor voltage of three-level neutral-point-diode-clamped (NPC) converter. This control method overcomes one of the main problems of this converter, which is the low frequency voltage oscillation that appears in the neutral point. The algorithm is based on Carrier-based Pulse Width Modulation (...

Recent research has shown a high interest in cascade 3/3 NPC inverter which is a series connection of two three-level diode-clamped inverters through R-L or motor load. Several techniques use per-phase switching redundant states to control the dual inverter with optimum operation. Other techniques employ the joint-phase redundancy to balance capaci...

This paper presents an alternate-cascaded technique for Z-source inverter with combined switched-inductor and transformer cells. By changing the transformer turn ratio, the number of switched-inductor cells and shoot-through duty cycle, the proposed cascaded inverter produces high voltage gain with distributing the stresses on the passive component...

The active power filter (APF) has been proved to be an advanced power electronics device, which is used to compensate harmonics and reactive power of non-linear loads. In this paper, the basic operation principle and structure of the three-phase APF are analyzed. The design issues and the implementation of the control algorithm using DSP are also p...

The new isolated step-up dc-dc converters based on the trans-Z-source/-quasi-Z-source networks are proposed in this paper. By adjusting the shoot-through duty cycle and changing the transformer turn ratio of the trans-Z-source network, the proposed trans-Z-source-based dc-dc converters have a lower shoot-through duty cycle compared to the conventio...

In this paper, a novel offset-based single-state pulse width modulation (PWM) method for achieving zero common-mode voltage (CMV) and reducing switching losses in multilevel inverters is presented. The specific active switching state of the zero common-mode (ZCM) voltage that approximates the reference voltage can be deduced from the switching stat...

Many researches and industrial applications have demonstrated unique and attractive features of multilevel inverters including high power quality, good harmonic performance, good electromagnetic compatibility, and low switching losses. In recent years, several new cascaded multilevel inverters are developed for increasing drive performance, reducin...

In many applications that need high voltage and high current, Multilevel inverter is chosen due to their advantages of lower THD, lower EMI generation and higher quality of output waveform. However, some problems exist because of their complex computation schemes and topology constructions. To solve the problems, field programmable gate array (FPGA...

The paper presents a novel universal offset based PWM method for 3f ac-ac matrix converter, whose characteristics can be controlled by the offset regulation. Typical characteristics of the offset based PWM control for the matrix converter will be described. The proposed PWM algorithm may help to simplify further study of PWM techniques for ac-ac ma...

Matrix converter is a single-stage Converter which directly connects a three- phase voltage source to a three- phase load without dc - elements. Therefore, the ac line side abnormal input can deteriorate its output characteristics. In this paper, the indirect space vector modulation method of the matrix converter is investigated and a feed-forward...

This paper presents a novel approach to analyze carrier-based discontinuous pulse width modulation (DPWM) method for multilevel inverters. The separation of the offset into the main and additional components shows the use for analyzing PWM control characteristics of multilevel inverters. The results are then applied to propose a novel minimized los...

In this paper, a novel analysis of a carrier based PWM method for multilevel inverters is presented. The space vector PWM and carrier based PWM correlations in multilevel inverters are investigated in a nominal two-level switching diagram. The obtained results can be applied to design various carrier PWM techniques. In this paper, a carrier based s...

This paper presents a sliding mode controller for induction motor fed with three level neutral point clamped (NPC) voltage source inverter (VSI) using sine pulse width modulation (SPWM) method. The controller has two loops: In the inner loop, the rotor fl flux and the motor torque are controlled using sliding mode approach. In the outer loop, the r...

The paper presents a method for controlling induction motors using a nonlinear internal model control (IMC) approach. The process model and the inverse model are developed in the rotor flux coordinate. The main advantage of the proposed method is that it easily specifies the performance (steady state error, transient response, etc.) and the robustn...

This paper presents a new carrier based overmodulation method in multiphase multilevel inverters for unbalanced DC voltage sources. Two-mode overmodulation in multiphase multilevel inverters is deduced in a similar way as in three-phase two-level inverter. It is different from 3-phase inverter, the overmodulation range in multiphase inverters is la...

In the paper, a novel analysis of carrier based PWM methods for multilevel inverters is presented. The space vector PWM and carrier based PWM correlations are investigated in a nominal two-level switching diagram. The obtained results will be applied to design various carrier PWM techniques. In this paper, a carrier based single-state PWM technique...

Single-state PWM technique (SS PWM) presents an optimised switching losses PWM scheme to be applied for multilevel inverter for possible reducing number of switchings in a sampling period. Nonlinear control characteristics and harmonic distortion factor can be significantly improved if the number of levels is high. To implement a single-state PWM c...

The paper presents a method for controlling induction motor using internal model control (IMC) approach. The forward and inverse models are nonlinear in the rotor flux coordinate. Simulation results show that the control system has good performance and robust against changes in motor parameters (rotor and stator resistances, inductances, rotor iner...

In the paper, a carrier based two-state PWM technique will be proposed. This method is advantageous for reducing switching losses compared with conventional PWM techniques. Compared with single-state PWM method, it can achieve a better linear control characteristic and harmonic distortion performance. The carrier based PWM approach of the proposed...

An on-line approach for calculating of conducting angles for a multilevel cascaded inverter is presented. The proposed method is a combination of equal voltage-second area and superposition principles. The conducting angle for each voltage level can be determined so that the fundamental component of the output voltage waveform of each H-bridge inve...

This paper presents a universal carrier based PWM method for multileg multilevel inverter on consideration of unbalanced dc voltage sources. Switching time diagram of PWM control in multilevel inverter can be transformed into a nominal switching two-level diagram. It will be shown the correlation between space vector PWM and carrier based PWM metho...

The paper introduces a universal carrier PWM technique for eliminating common mode voltage in multilevel inverters. The correlation between carrier PWM and space vector PWM will be also presented. Switching state sequence can be described in a nominal switching diagram. A linear overmodulation is also included.

Three-phase 4-switch voltage source inverters are advantageous for reduced number of power switches. For these topologies, space vector pulse width modulation (SVM) methods have been commonly used for controlling the circuit. This paper presents a novel carrier based PWM method for 4-switch inverters, which is simple and flexible. Linear over modul...

Nowadays, an intensive development of multilevel inverters has been seen in hybrid and fuel cell electric vehicles. For this, a high voltage cascade inverter with step pulse PWM strategy is an applicable topology as it can reduce electromagnetic interference as well as switching losses on power devices. The converter is usually controlled with a lo...

Recently, an on-line step pulse PWM method has been introduced for cascade multilevel inverters. The simplicity of this method was derived from the principle control between two defined trajectories. For achieving good output performances, several exact angular sets are needed to be determined in advance by solving the trigonometric equations. If t...

Recently, for multilevel inverters, the various PWM performances can be properly controlled by an offset controller in the carrier based PWM modulator. It has shown a generalised algorithm for realizing a discontinuous PWM technique for defined common mode. For applications with variable load power factor, reduction of switching losses can be impro...

This paper presents generalized carrier PWM algorithms for balancing load voltages for NPC multilevel inverters while dc-voltage sources are unbalanced or oscillating. Simplicity of algorithms, possible applying to any level inverters are the advantages of the proposed PWM method. The ability of separate control of PWM modes, dc voltage balancing (...

For cascade multilevel inverters, the step pulse waveform PWM method is a typical solution in high-power applications. Since there exists a big problem of solving transcendent equations, which requires a long time computation, the off-line approach is commonly used in practice. In contrary, an on-line approach can present a more flexible solution f...

This paper presents the development of neural-network-based controller of space vector modulation (ANN-SVPWM) for voltage-source inverters (VSI). This ANN-SVPWM controller completely covers the undermodulation and overmodulation modes with operation extended linearly and smoothly up to square wave (six-step) by using theory of modulation between th...

This paper presents a simple graphical approach to compare the switching losses of various carrier SVPWM methods for multilevel inverters. Similarly, the harmonic distortion factors can be indirectly validated. There have been deduced SVPWM methods related to maximum, medium and minimum zero sequence functions. As a result of comparison, the SVPWM...

The paper presents a theoretical analysis of the correlation between carrier-based unipolar PWM (CPWM) and space-vector PWM (SVPWM) for the entire modulation-index range of multilevel invertors, including overmodulation. By presenting corresponding parameters of vector redundancies in a zero-sequence function, the carrier-based PWM has matched the...

The Selective Harmonic Elimination (SHE) PWM technique has become a significant PWM method for less switching loss for voltage source inverter. For off-line approach, the various sets of commutation angles in relation to modulation index are commonly determined in advance and look-up tables are required. This trouble can be avoided in on-line appro...

A This paper presents a systematical approach to study carrier based PWM techniques in diode-clamped and cascade multilevel inverters by using the proposed multi-modulating pattern method. This method is based on description of controllable redundant parameters in the modulating signals. The CPWM methods can be described in a unified mathematical f...

A novel approach to analyse a four-leg multilevel inverter as a model of two simple inverters in series is presented and a carrier-based SVPWM method is proposed. To obtain the optimised switching loss, the zero sequence function is controlled by redundant parameters. The PWM analysis is simplified, and the use of complicated three-dimensional SVPW...

This paper presents a study on a current control of a PM synchronous motor which is fed by two-level voltage source inverter in the high modulation index area. In order to increase dynamic response and extend speed limit caused by limit voltage, overmodulation methods is generally used. However, the voltage ripple in the overmodulation region gener...

This paper presents a new approach to implement a carrier based PWM modulator in a multi-level inverter, using correlation between carrier based PWM and space vector PWM. Using the performed relation, different CPWM methods in a multilevel inverter can be simply clarified and appropriately modified for obtaining required performance. In this paper,...

This paper presents a new carrier based PWM method to control the three phase four wire inverters. An equivalent circuit model of two-level inverter has been proposed, presenting a redundancy function in the zero sequence voltage. Its application has been used to explain simply the characteristics of the three phase four wire inverter topologies. T...

A novel technique for studying carrier wave based pulse width modulation inverters in the overmodulation range is presented. The continuous transition from zero modulation index to unity value of six-step mode may be obtained. The method is demonstrated by simulation.

A two-mode overmodulation in two-level VSI using the control principle between limit trajectories is presented. The control principle between limit trajectories is used to ensure linear modulation from linear range of space vector pulse width modulation to six step mode and two-mode is employed to get better performance of overmodulation. The propo...

Hybrid and cascade multilevel inverter topology has presented a modern trend for reducing the power and control circuits in applications. A proper PWM control technique can utilise the design simplicity for achieving similar output performance of conventional multilevel inverters. This paper will present a simple carrier PWM control technique for c...

Many hybrid multilevel inverter topologies have been developed for reduction of harware configuration. Proper designing of control method can optimise the selection of semiconductor devices with different characteristics and therfore utilising the inverter performance as a whole. One of the active issues in hybrid inverters presents an optimised PW...

The step pulse waveform PWM method is a typical solution in high power cascade inverters. A big problem is to solve transcendent equations, that cause much consuming time. Then an off-line approach is commonly acceptable in practice. In contrary, an on-line approach would be a more elegant solution and no large memmory is needed. This paper present...

ČVO: 26-04-9 Autoref. kand. dis. autoreferát - datum: 1991 autoreferát - rozsah: 17 s. datum obhajoby: 19911023