Hysteresis band current controller based field-oriented control for an induction motor driven by a direct matrix converter

© 2017 IEEE. This paper presents work on the hysteresis band control for output current regulation in a direct matrix converter in order to drive an induction motor. The hysteresis band controller offers excellent dynamic performance. It has been extensively researched for the voltage source inverter and inverter based drive systems, but it has not been investigated within the context of a matrix converter or a matrix converter based motor drive. Firstly, this paper proposes a fixed-band hysteresis current controller for a matrix converter to track the prescribed current references, and then a sinusoidal-band hysteresis current controller is proposed. Both methods have fast dynamic performance and they inherently integrate the line modulation technique of the virtual rectifier stage into the overall modulation. The extra modulation stage is not required and the surge current is inherently prevented. The sinusoidal-band hysteresis controller demonstrates that it generates lower harmonic content at the expense of the higher average switching frequency. Following this, both methods are tested as a drive for an induction motor with field-oriented control. With the matrix-converter-based drive system, one significant benefit is that the braking chopper is removed due to the bidirectional feature. The methods are simple and have light computation burden. The obtained results demonstrate the effectiveness and feasibility of the proposed scheme. The experimental work is being carried out to support the proposed scheme

Applications of the direct space vector modulation controlled matrix converter as the unified power flow controller

© 2016, Institution of Engineering and Technology. All rights reserved. This paper investigates the matrix converter when working as the unified power flow controller which can regulate the active reactive power flowing in a transmission line. A conventional unified power flow controller usually has a DC capacitor; this is removed in the proposed controller. This reduces the volume, improves the efficiency and lifetime, and eliminates the DC voltage control. The detailed direct space vector modulation method for the matrix converter is described. Based on this modulation scheme, a PID controller is designed in order to control the power flow. Coupling effects are suppressed by feedback of the coupling components to the controller. The proposed strategy can control the active and reactive power efficiently and effectively. Simulations based on MATLAB/Simulink help verify the feasibility and effectiveness of the scheme

Modelling the Effects of Nifedipine on Ventricular and Myometrial Cells of Pregnant Rats

In this study we have used computational models to investigate the effects of nifedipine on two different cell types; the rat ventricular cell and the rat myometrial cell. Nifedipine is a calcium-channel blocker commonly used by health services around the world to treat both cardiovascular conditions (such as high blood pressure) and as a tocolytic to treat pre-term birth. The latter usage is prohibited in pregnant patients with pre-existing heart conditions. By applying discrete blocks to the L-Type calcium channels in each cell model we were able to simulate the presence of nifedipine at varying concentrations. Using the electrical and ionic responses to blocking these channels as indicators, we have been able to quantify and describe the effects of nifedipine in each cell type and compare them qualitatively. Although any level of block will reduce the maximum level of intracellular calcium in the myometrial cell, a 60% block or higher is required to produce a change in the morphology of the calcium transient. It remains to be shown if the dose required to achieve this could result in a patient with a pre-existing heart condition experiencing hypotension or other pathological cardiac conditions during labor, if nifedipine is used as a tocolytic

Experimental Investigation of Ultracapacitor Impedance Characteristics

© 2015 The Authors. Published by Elsevier Ltd. Ultracapacitors (UCs) are being increasingly studied and deployed as a short-term energy storage device in various energy systems including uninterruptible power supplies, electrified vehicles, renewable energy systems, and wireless communication. They exhibit excellent power density and energy efficiency. The dynamic behavior of a UC, however, strongly depends on its impedance characteristics. In this paper, the impedance characteristics of a commercial UC are experimentally investigated through the well-adopted Electrochemical Impedance Spectroscopy (EIS) technique. The implications of the UC operating conditions (i.e., state of charge (SOC) and temperature) to the impedance are systematically examined. The results show that the impedance is highly sensitive to temperature and SOC; and the temperature effect is more significant. The experimental design and multi-condition impedance analysis provides prudent insights into UC system integration, dimensioning, and energy management strategy synthesis in advanced energy systems

A novel sliding mode controller for DC-DC boost converters under input/load variations

© 2015 IEEE. In this paper a simple sliding mode controller based on the averaging state space model is proposed for a DC-DC boost converter. It is demonstrated to be easily implemented and has time-variant sliding coefficients. The proposed controller can effectively regulate the output voltage by controlling the switch states (through the dynamic duty cycles) even when the input voltage, load or output command varies. Furthermore the controller is independent of the inductor current and the load, although the load value is needed when designing the sliding coefficients. The constant switching frequency is maintained thus simplifying the design procedure, enhancing the regulation properties and benefiting the filter design. The controller has good dynamic response, overshoot damping and robustness. Comparative simulations are carried in MATLAB/Simulink between the proposed approach and a widely used PID controller to verify the effectiveness and feasibility of the proposed method

Predictive voltage control of direct matrix converter with reduced number of sensors for the renewable energy and microgrid applications

© 2017 IEEE. This work proposes and investigates a renewable energy distributed generation system involving a matrix converter with an output filter working as a stable voltage supply. This is especially relevant for the stand-alone operation of a renewable energy microgrid where a stable sinusoidal voltage with prescribed amplitude and frequency under various load conditions is the main control objective. A controllable input power factor is preferred. In this paper, the model predictive control is employed to regulate the matrix converter output voltages which in turn are the supply for systems of the following stage. To reduce the number of required measurements and sensors, the work designs observers and makes use of the switch matrix. In addition to the regulation of the sinusoidal output voltages and input power factor, the control scheme deals with the common-mode voltage. The switching frequency is also considered in the controller to reduce the switching losses and keep the average switching frequency constant. In addition, the voltage transfer ratio can be improved at the cost of input current distortion. Supplying DC loads is feasible with this proposed control method. The controller is tested under various conditions including non-linear loads, DC loads and unbalanced input conditions to show it is effective, simple and easy to implement. Simulation results corroborate the effectiveness of the proposed controller and applications

Electromagnetic optimal design of a linear induction motor in linear metro

An improved T-model equivalent circuit of a single-sided linear induction machine (SLIM) is proposed. The analysis utilizes a set of one-dimensional air gap flux linkage equations. The model takes longitudinal end and transversal edge effects into consideration. These have to account for primary terminal half-filled slots, secondary back-iron saturation and skin effect in the secondary conducting sheet. In the circuit, several coefficients are obtained by use of the dummy electric potential method in conjunction with consideration of the complex power equivalence between the primary and secondary sides. The coefficients derived include the longitudinal end effect coefficients K r and Kx, transversal edge effect coefficients C r and Cx, and skin effect coefficient Kf. The accuracy of the T-model is validated using comparison to a set of measured data under constant current - constant frequency conditions. These were taken from the Intermediate Capacity Transit System (ICTS) in Canada. An optimal design scheme for the SLIM is addressed. The application used for the optimization is a prototype propulsion system in a high temperature superconducting (HTS) maglev drive. The efficiency and primary weight are chosen as optimal objective functions while the thrust, power factor and other performance indexes are calculated. © 2010 IEEE

High colloidal stability of gold nanorods coated with a peptide-ethylene glycol: Analysis by cyanide-mediated etching and nanoparticle tracking analysis

The stability of gold nanorods was assessed following coating with various charged or uncharged ligands, mostly peptides. Highly stable monodispersed gold nanorods were obtained by coating CTAB-stabilized gold nanorods with a pentapeptide with C-terminal ethylene glycol units (peptide-EG). UV-vis spectroscopy of these nanorods suspended in saline solutions indicated no signs of aggregation, and they were easily purified using size-exclusion chromatography. A more stringent measure of nanorod stability involved observing changes in the UV-vis absorbance of gold nanorods subjected to etching with cyanide. The max absorbance of peptide-EG coated nanorods red-shifted in etchant solution. The hypothesis that changes in the nanorod aspect ratio led to this red-shift was confirmed by TEM analysis, which showed pit formation along the transverse axis. The etching process was followed in solution using nanoparticle tracking analysis. The red-shift was shown to occur while the particles remained mono-dispersed, and so was not due to aggregation. Adding both etchant solution and peptide-EG to the nanorods was further shown to allow modulation of the max red-shift and increase the etchant resistance of peptide-EG nanorods. Thus, very stable gold nanorods can be produced using the peptide-EG coating approach and their optical properties modulated with etchant

Capacity of Cooperative Vehicular Networks with Infrastructure Support: Multiuser Case

© 1967-2012 IEEE. Capacity of vehicular networks with infrastructure support is both an interesting and challenging problem as the capacity is determined by the interplay of multiple factors including vehicle-to-infrastructure (V2I) communications, vehicle-to-vehicle (V2V) communications, density and mobility of vehicles, and cooperation among vehicles and infrastructure. In this paper, we consider a typical delay-tolerant application scenario with a subset of vehicles, termed Vehicles of Interest (VoIs), having download requests. Each VoI downloads a distinct large-size file from the Internet and other vehicles without download requests assist the delivery of the files to the VoIs. A cooperative communication strategy is proposed that explores the combined use of V2I communications, V2V communications, mobility of vehicles and cooperation among vehicles and infrastructure to improve the capacity of vehicular networks. An analytical framework is developed to model the data dissemination process using this strategy, and a closed-form expression of the achievable capacity is obtained, which reveals the relationship between the capacity and its major performance-impacting parameters such as inter-infrastructure distance, radio ranges of infrastructure and vehicles, sensing range of vehicles, transmission rates of V2I and V2V communications, vehicular density, and proportion of VoIs. Numerical result shows that the proposed cooperative communication strategy significantly boosts the capacity of vehicular networks, especially when the proportion of VoIs is low. Our results provide guidance on the optimum deployment of a vehicular network infrastructure and the design of a cooperative communication strategy to improve the capacity