Simplified quasi‐Z source indirect matrix converter

Conventional matrix converters have a limited voltage gain less than 0.866 and also require many power switches and additional input filter that ensures a low input current harmonics to the grid. Quasi‐Z source (qZS) indirect matrix converter can provide high voltage gain and ensure a sinusoidal input current without additional input filter, which requires 12 power switches in rectifier stage. In this paper, a simplified qZS indirect matrix converter is proposed to overcome aforementioned limitations and achieve (1) higher voltage gain than 0.866, (2) less power switches, and (3) LC‐filter function integrated in qZS network to avoid additional filter. The new converter's operating principle and equivalent circuits are analyzed, and the modulation method is presented. The input current closed‐loop control is employed to implement sinusoidal input current waveform even though the proposed converter has less power switches and without extra input filter. A test bench is used to verify the simplified qZS indirect matrix converter and control methods. Simulation and experimental results identically validate the proposed converter system with wide voltage gain range and low input current harmonics. Copyright © 2014 John Wiley & Sons, Ltd.     

A novel quasi‐Z‐source indirect matrix converter

A new type of three‐phase quasi‐Z‐source indirect matrix converter (QZS‐IMC) is proposed in this paper. It uses a unique impedance network for achieving voltage‐boost capability and making the input current in continuous conduction mode (CCM) to eliminate the input filter. The complete modulation strategy is proposed to operate the QZS‐IMC. Meanwhile, a closed‐loop DC‐link peak voltage control strategy is proposed, and the DC‐link peak voltage is estimated by measuring both the input and capacitor voltages. With this proposed technique, a high‐performance output voltage control can be achieved with an excellent transient performance even if there are input voltage and load current variations. The controller is designed by using the small‐signal model. Vector control scheme of the induction motor is combined with the QZS‐IMC to achieve the motor drive. A QZS‐IMC prototype is built in laboratory, and experimental results verify the operating principle and theoretical analysis of the proposed converter. The simulation tests of QZS‐IMC based inductor motor drive are carried out to validate the proposed converter's application in motor drive. Copyright © 2013 John Wiley & Sons, Ltd.     

Constant switching frequency-based delta-sigma modulation of single-phase AC–AC zeta converter

Direct pulse width modulated (PWM) AC–AC converters, derived from their DC–DC counterparts, serve as promising media for AC–AC power conversion because they offer benefits, such as single-stage power conversion, absence of bulky DC links, and small footprint. In this study, a single-phase ( $1-\varphi$) AC–AC zeta converter was analyzed under buck, boost, and buck-boost operations. Delta-sigma modulation (DSM) technique, known for its simple logic implementation, excellent reference-tracking property, robust control, and fast transient response, was employed for the load voltage control of a $1-\varphi$ AC–AC zeta converter. However, the conventional DSM technique relies on a fixed hysteresis band (FHB) for restricting the integrated (sigma) error (delta) between the reference and estimated control voltages within a narrow band, which causes the converter to operate at a variable switching frequency (VSF). Although VSF enhances the converter performance with low total harmonic distortion (THD) and high degree of flexibility over waveform quality, it poses serious implications such as higher switching losses, putting more strain on thermal management of switches. This paper presents a constant switching frequency-based DSM technique based on an adaptive hysteresis band (AHB) for a $1-\varphi$ AC–AC zeta converter. The converter is controlled using FHB-DSM and AHB-DSM techniques, and a comparison is drawn between the two in terms of various performance indices. In this comparison, FHB-DSM serves as a benchmark and an optimum switching frequency based on AHB-DSM technique is determined, which exhibits low switching losses while maintaining the same THD limits, dynamic response, and waveform quality as that of FHB-DSM technique. The proposed strategy was validated by simulation studies in MATLAB/SIMULINK software. Furthermore, a real-time simulator, OPAL-RT (OP4510), was used to validate the study with real-time implementation.     

Space vector pulse‐width modulation theory and solution for Z‐source inverters with maximum constant boost control

The theory of space vector pulse‐width modulation (SVPWM) technique for the three‐phase Z‐source inverter has been introduced in detail, and a novel implementation scheme based on the maximum constant boost control method is presented in this paper. Like the traditional carrier‐based maximum constant boost control strategy, the proposed control method is able to achieve the maximum voltage boost ability while always keeping the shoot‐through duty ratio constant. Besides, it inherits the advantages from the SVPWM technique. Compared with carrier‐based strategies, it has wider linear operation range and is easier for digital implementation. The number of switching transition in each switching cycle is reduced, which significantly decreases switching losses. To investigate the advantages of lessening switching losses, three optimal switching patterns are proposed and compared with the carrier‐based strategy. It is demonstrated that the number of switching transition can be reduced by 60% at most by the proposed SVPWM‐based control method. All the theoretical analysis has been validated by the simulation results in MATLAB/Simulink at last. Copyright © 2012 John Wiley & Sons, Ltd.     

A three‐phase hybrid stepping motor drive system combined with position‐sensorless closed‐loop control

This paper proposes a drive system for a three‐phase hybrid stepping motor, combining sensorless closed‐loop control with conventional open‐loop control. It is characterized by sophisticated control providing both prevention of pulling out from synchronism and suppression of natural rotor oscillation, without any position sensor attached to the motor shaft. A switching technique in chopper control which can enlarge the speed range controllable in the sensorless closed‐loop control is described. Starting and stopping sequences are developed to reduce mechanical natural oscillation produced in the transient state. Finally, the proposed drive system is compared experimentally with a conventional constant‐current open‐loop drive system. It is shown that the proposed drive system can perform the switchover from starting to sensorless closed‐loop operation within 20 ms, and can reduce the natural oscillation caused just after positioning. © 2000 Scripta Technica, Electr Eng Jpn, 131(3): 80–90, 2000     

A new single‐phase high‐power‐factor converter with buck and buck–boost hybrid operation

In recent years, a wide variety of high‐power‐factor converter schemes have been proposed to solve the harmonic problem. The schemes are based on conventional boost, buck, or buck–boost topology, and their performance, such as output voltage control range in the boost and buck topology or efficiency in the buck–boost topology, is limited. To solve this, the authors propose a single‐phase high‐power‐factor converter with a new topology obtained from a combination of buck and buck–boost topology. The power stage performs the buck and buck–boost operations by a compact single‐stage converter circuit while the simple controller/modulator appropriately controls the alternation of the buck and buck–boost operation and maintains a high‐quality input current during both the buck and buck–boost operations. The proposed scheme results in a high‐performance rectifier with no limitation of output voltage control range and a high efficiency. In this paper, the principle and operation of the proposed converter scheme are described in detail and the theory is confirmed through experimental results obtained from 2‐kW prototype converter. © 2000 Scripta Technica, Electr Eng Jpn, 131(3): 91–100, 2000     

A comprehensive study of space vector pulse‐width modulation technique for three‐phase Z‐source inverters

The space vector pulse width modulation (SVPWM) technique has received much attention for three‐phase Z‐source inverters (ZSIs). The differences and connections between the SVPWM technique for ZSIs and for traditional voltage source inverters have been discussed as well. By selecting different null state and shoot‐through state, three switching patterns with different switching numbers have been studied, and the harmonic spectrums of these three patterns are demonstrated. In this paper, the solutions of maximum boost control and constant boost control methods using SVPWM techniques with less switching actions have been proposed and compared with the carrier‐based strategies. Selected experimental results have been provided to validate the theoretical analysis. This work will be beneficial for understanding the SVPWM concept and modulation techniques of the three‐phase ZSIs. Copyright © 2015 John Wiley & Sons, Ltd.     

Steady‐state analysis of a novel ZVT interleaved boost converter

In this paper, a novel soft‐switched interleaved boost converter composed of two‐cell boost conversion units and an auxiliary circuit is proposed and investigated. The proposed auxiliary circuit is implemented using only one auxiliary switch and a minimum number of passive components without an effective increase in the cost and the complexity of the converter. The main advantage of this auxiliary circuit is that it not only provides zero‐voltage‐transition (ZVT) for the main switches but also provides soft switching for the auxiliary switch and diodes. Though all semiconductor devices operate under soft switching, they do not have any additional voltage and current stresses. The proposed converter operates successfully in soft‐switching operation mode for a wide range of input voltage level and the load. In addition, it has advantages such as fewer structure complications, lower cost and ease of control. Since the two‐cell interleaved boost units are identical, operational analysis and design for the converter module become quite simple. In this study, the detailed steady‐state theoretical analysis of the proposed converter is presented, which is verified exactly by simulation and experiments carried out on a prototype of a 120 W and 50 kHz/cell interleaved boost converter. The practical results confirm the results obtained from theoretical analysis. Copyright © 2010 John Wiley & Sons, Ltd.     

A step‐up PWM DC–DC converter for renewable energy applications

A step‐up pulse width modulation (PWM) direct current (DC)–DC converter is presented in this paper, which has its origin in quasi Z‐source inverter. Analysis of this converter in steady state is presented, and relevant expressions are derived for the proposed converter operating in continuous conduction mode. The power loss expressions for each component of the converter are derived, and thereby, obtained expressions for overall converter efficiency are presented. Further, a dynamic model is derived to design an appropriate controller for this converter. The simulation and experimental results are presented to support the theoretical analysis. The advantages such as continuous input current, high step‐up gain at lower duty ratio, and common ground for source, load, and switch makes the converter suitable for renewable energy applications. Copyright © 2015 John Wiley & Sons, Ltd.     

Non‐invasive chaos control of DC–DC converter and its optimization

The frequency‐domain‐based realization condition related to a novel non‐invasive chaos control is presented in this paper. According to the common piecewise‐linear characteristics of PWM‐controlled DC–DC converter system, a general expression for its Jacobian matrix is derived for optimizing the control parameters of the proposed non‐invasive chaos control. The relevant simulation and experiment results about the application of the chaos control to a voltage‐mode Buck converter are given, which confirm the feasibility of the parameter‐optimization method and the validity of the proposed non‐invasive chaos control. Copyright © 2010 John Wiley & Sons, Ltd.     

Performance improvement of repetitive controlled PWM inverters: A phase‐lead compensation solution

The compensation of the phase lag plays an important role in the improvement of convergence rate, tracking accuracy, and robustness of repetitive controller. However, it is often difficult to compensate the system phase lag exactly due to variation of the load and unknown disturbances. An alternative way is to provide a simple but effective phase compensation to compensate the phase lag in a frequency band that contains the major tracking error components. With this motivation, a repetitive control scheme with a linear phase‐lead compensator is proposed and applied to the control of constant‐voltage constant‐frequency pulse‐width modulated DC–AC inverters. Detailed analysis of phase compensation on system stability is provided, and conditions for the design of phase compensation are derived. The experimental results under different loads and load changes show that the proposed scheme can achieve high tracking accuracy, low total harmonic distortion, and fast dynamic response. Copyright © 2008 John Wiley & Sons, Ltd.     

Calculation of steady‐state solution of parallel‐connected buck converters with active current sharing and its parameter sensitivity

In this paper, the effect of active current‐sharing control on the steady‐state operation of parallel‐connected buck converters is investigated. The system under study consists of N voltage‐mode‐controlled buck converters connected in parallel. Three kinds of active current‐sharing schemes are considered, namely, master–slave scheme with automatic master, master–slave scheme with dedicated master, and democratic scheme. Using the principle of charge balance, the mechanism of the operating point drift arising from active current sharing is examined. A general formulation of the steady‐state solution under active current sharing is derived. Moreover, detailed parameter sensitivity analysis is performed to evaluate the effect of parameters' variation on the operating point. The results from sensitivity analysis can be used to categorize parameters for facilitating practical design. Computer simulations are presented to verify the analytical results. Copyright © 2010 John Wiley & Sons, Ltd.     

A new control strategy with fault ride‐through capability for VSC‐based offshore high power oil pump motor power supply system

In offshore oil platforms, high voltage and power motors (HV motors) are needed when transporting oil to the land. Traditional platform diesel generators cannot support so much power, so the required system must be supplied by the onshore AC grid. In general, when there is a long distance between the offshore platform and the shore, a DC transmission system is more efficient. This paper proposes a power supply approach for these motors using a voltage source converter (VSC) and derives the mathematical model for it. This method combines motor drive theory and studies in DC transmission field. Compared with the traditional motor control, this method, which makes full use of the advantages of VSC, can simplify the control strategy. And by using the Q–U droop characteristic, the strategy improves the system stability and fault ride‐through capability. Simulation is carried out in PSCAD/EMTDC, and the results verify the validity of the control method. © 2016 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Global hybrid modeling and control of a buck converter: A novel concept

Several attempts have been made to design suitable controllers for DC–DC converters. However, these designs suffer from model inaccuracy or their inability to desirably function in both continuous and discontinuous current modes. This paper presents a novel switching scheme based on hybrid modeling to control a buck converter using mixed logical dynamical (MLD) methodologies. The proposed method is capable of globally controlling the converter in both continuous and discontinuous current modes of operation by considering all constraints in the physical plant such as maximum inductor current and capacitor voltage limits. Different loads and input voltage disturbances are simulated in MATLAB and results are presented to demonstrate the suitability of the controller. The transient and steady‐state performance of the closed‐loop control over a wide range of operating points shows satisfactory operation of the proposed controller. Copyright © 2008 John Wiley & Sons, Ltd.     

Steiglitz–McBride adaptive notch filter based on a variable‐step‐size LMS algorithm and its application to active noise control

This paper proposes a new Steiglitz–McBride (SM) adaptive notch filter (SM‐ANF) based on a robust variable‐step‐size least‐mean‐square algorithm and its application to active noise control (ANC). The proposed SM‐ANF not only has fast convergence but also has small misadjustment. The variable‐step‐size algorithm uses the sum of the squared cross correlation between the error signal and the delayed inputs corresponding to the adaptive weights. The cross correlation provides robustness to the broadband signal, which plays the role of noise. The proposed SM‐ANF is computationally simpler than the existing Newton/recursive least‐squares‐type ANF. The frequency response of the new SM‐ANF has a notch depth of about ?25 dB (for each of the three frequencies considered) and has spectral flatness within 5 dB (peak to peak). This robust notch filter algorithm is used as an observation noise canceller for the secondary path estimation of an ANC system based on the SM method. The ANC with proposed SM‐ANF provides not only faster convergence but also an 11‐dB improvement in noise attenuation over the SM‐based ANC without such a SM‐ANF. Copyright © 2015 John Wiley & Sons, Ltd.     

Swing‐up and stabilization control of a cart– pendulum system via energy control and controlled Lagrangian methods

This paper addresses a swing‐up and stabilizing problem for a cart– pendulum system, which consists of a pendulum and a motor‐driven cart. Existing methods are based on the strategy of swing‐up of the pendulum by energy control methods, then switching the controllers to balance the pendulum when it approaches the upright position. The switching angle influences significantly control performance, so the pendulum might fall down if the angle is inadequately chosen. This paper proposes a swing‐up and stabilizing control method which makes it possible to determine an appropriate switching angle more arbitrarily. In addition to the energy control method for swing‐up, a stabilizing method based on controlled Lagrangians is adopted instead of a linear controller. The attractive domain of the closed‐loop system with this method can be known in advance and is wider than with linear controllers. In this way, our proposed control strategy overcomes the difficulty in choosing the switching angle of the controllers. An experimental result illustrates the effectiveness of the proposed method. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 160(4): 24– 31, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20534