Objective To meet the training needs of metro drivers and maintenance personnel in studying metro control circuit principles, a MTCCS (metro train control circuit simulation system) is designed to ...address the issues of high coupling and complex control logic in metro control circuits. Method The overall structure of the MTCCS is introduced, and a logical control model of metro train control circuit is established. The depth-first path search algorithm is used to search for all valid paths in the network topology diagram, establishing the mathematical relationship between nodes, branches, valid paths and component states, and cooperating with relay linkage control to establish the logical control model. Taking the control circuit of Shanghai Rail Transit Line 15 as example, simulation testing is conducted on proposed control circuit simulation system. Result & Conclusion The proposed control circuit simulation system can meet the learning and training needs of metro drivers and maintenance personnel in u
Overhead Requirements for Stateful Memristor Logic Xuan Hu; Schultis, Michael J.; Kramer, Matthew ...
IEEE transactions on circuits and systems. I, Regular papers,
2019-Jan., 2019-1-00, Letnik:
66, Številka:
1
Journal Article
Recenzirano
Memristors are being explored as a potential technology to replace CMOS for logic-in-memory systems that exploit the memristive non-volatility. Memristors are two-terminal, non-volatile device that ...exhibit a variable resistance that is dependent on the applied voltage history of the device, providing the capability to store and process information within the same structure. The ability of memristors to perform logic has been previously demonstrated, but previous analyses of memristor logic efficiency have not included the overhead CMOS circuitry that is required to control memristor logic operations. In this paper, the required overhead CMOS circuitry for implementing logic with memristors is evaluated for standard logic gates and a one-bit full adder to enable an analysis of the overall system efficiency. The results show that the number of CMOS devices in the overhead circuitry can be upwards of 50 times that of a conventional CMOS implementation, and that the power-delay product of the memristor logic with overhead circuitry is roughly one billion times greater than for conventional CMOS circuits. These results enable the conclusion that the overhead circuit requirements for stateful memristor logic threaten to negate any efficiency improvements that are achieved by the memristors themselves.
Objective In the early operation stage of Jinan Metro Line 3, multiple sporadic high-speed circuit breaker closing failures are reported. To improve the reliability of train operation, it is ...necessary to optimize the high-speed circuit breaker control circuit in the traction system. Method According to the relevant closing command and the component status when a closure failure of the high-speed circuit breaker on Line 3 train occurs, and in accordance with the control logic principle of the high-speed breaker, the causes of the occasional closure failure are analyzed and the optimization measures are put forward. Result & Conclusion The causes of the occasional closure failure are that in the process of closure control of high-speed circuit breaker, the induced electromotive force generated at both ends of the high-speed circuit breaker coil makes the closing power insufficient, resulting in the failure closure of the breaker. The improvement measure is to connect freewheel diodes at both ends of the h
Single-phase split induction motors consist of an auxiliary coil, a main winding and a centrifugal switch that separates the auxiliary coil. The starting torque of this motor is not large, and a ...resistance has to be added with the additional coil to increase the starting torque. Also, a mechanical centrifugal switch is used to disconnect the auxiliary coil. The motor also has another drawback that it has a constant speed. The aim of this research is to replace the added resistance with a current transformer that has a predetermined resistance and connected in series with the auxiliary coil such that it results in a maximum starting torque. In addition, it sends a signal to a control circuit that disconnect/connect the auxiliary coil through an electronic switch connected in series with the auxiliary coil. The connection/disconnection of the switch depends on the motor current not the motor speed to overcome the problem of switch false triggering due to motor overloading. The new technique increases the overall efficiency of the motor. MATLAB is used to simulate the system and verify the mathematical model.
Improvement of the efficiency of photovoltaic system based on new maximum power point tracking (MPPT) algorithms is the most promising solution due to its low cost and its easy implementation without ...equipment updating. Many MPPT methods with fixed step size have been developed. However, when atmospheric conditions change rapidly , the performance of conventional algorithms is reduced. In this paper, a new variable step size Incremental Conductance IC MPPT algorithm has been proposed. Modeling and simulation of different operational conditions of conventional Incremental Conductance IC and proposed methods are presented. The proposed method was developed and tested successfully on a photovoltaic system based on Flyback converter and control circuit using dsPIC30F4011. Both, simulation and experimental design are provided in several aspects. A comparative study between the proposed variable step size and fixed step size IC MPPT method under similar operating conditions is presented. The obtained results demonstrate the efficiency of the proposed MPPT algorithm in terms of speed in MPP tracking and accuracy.
Schematic of solar-panel connections in the experiments PV system based on Flyback and dsPIC30F4011
Display omitted
•A novel variable step-size IC MPPT is investigated.•Experimental prototype was implemented using dsPIC30F4011 and Flyback converter.•Simulation and experimental results of the proposed method are presented.•Good results in terms of accuracy, response time, overshoot, oscillation.
A low-power pulse width modulation (PWM) control circuit for high-frequency switching direct current (DC)–DC converters based on a one-shot circuit is proposed. The proposed PWM control circuit ...eliminates the use of a high-power comparator and ramp generator that is conventionally used to generate the PWM waveform. The design is validated through simulation in a 0.13-μm process. The proposed circuit operating at 20 MHz demonstrates greater than 20× reduction in power consumption compared with the conventional PWM circuit over a duty-cycle range of 10–90%.
Magnetic field energy harvester (MEH) based on current transformers has emerged as a promising method for powering mass sensors in smart grids. However, a significant challenge lies in the ...insufficient power harvested at low primary currents. Aiming at resolving this shortcoming, a novel maximum power point (MPP) reaching method based on a low-power analog control circuit is proposed in the present study. The main objective of this method is to improve the performance of the MEH. The MPP is achieved by controlling the voltage of the dc side of the rectifier bridge based on the optimal load voltage characteristics of the MEH. The analog control circuit is designed using low-power analog devices and megaohm-level resistors, eliminating the need for a microcontroller. The performed analyses revealed that the calculated maximum power loss of the proposed approach is only 81.81 μW. Experimental results demonstrate a remarkable increase in MEH power output ranging from 101.39% to 149.89% compared to commercial circuits at currents ranging from 1 to 10 A.
This study describes the particular development and investigation of a static and dynamic simulation model and its application to improve the start-up process of a combined cycle power plant. ...Generally, the power plant system and control design mean highly complex interactivities. The dynamic simulation models using powerful computers are effective tools for studying and understanding the operating characteristics of power plants to meet and improve the design, control strategy and operational requirements. The heat recovery steam generator (HRSG) is modeled by using commercial simulation software named
advanced
process
simulation
software (APROS). The HRSG model includes an advanced control philosophy and turbine bypass systems to have a high level of accuracy, especially during hard transients. The comparison between the simulation results and measured data is documented. The received results proved and embodied that the simulation is both very reliable to estimate the real HRSG dynamic behaviour and capable to predict the operational processes. Through a parametric study, the start-up time will be reduced while keeping the life-time consumption of critically stressed components under control.
This paper presents analytic and experimental comparisons for high-efficiency class-F and inverse class-F amplifiers. The analytic formula of the efficiencies, output powers, dc power dissipations, ...and fundamental load impedances of both amplifiers are derived from the ideal current and voltage waveforms. Based on the formula, the performances are compared with a reasonable condition: fundamental output power levels of class-F and inverse class-F amplifiers are conditioned to be identical. The results show that the inverse class-F amplifier has better efficiency than that of class-F amplifiers as the on-resistance of the transistor increases. For experimental comparison, we have designed and implemented the class-F and inverse class-F amplifiers at I-GHz band using a GaAs MESFET and analyzed the measured performances. Experimental results shows 10% higher power-added efficiency of the inverse class-F amplifier than that of the class-F amplifier, which verifies the waveform analysis.
•Fully controlled cooling and cleaning system of PV module is implemented.•Water requirement and power consumption of cooling and cleaning module are minimized.•Continuity of water flow in the ...distribution pipe is studied.•Increase of output power and efficiency of module due to cooling and cleaning is achieved.•Less thermal degradation is attributed to uniform temperature distributions.
This study investigated experimentally the performance due to automatic cooling and surface cleaning of Photovoltaic (PV) module installed on the roof of a building in hot arid area as compared with that of a module without cooling and cleaning. The module cooling is controlled automatically according to the rear side temperature via rejection of none-converted solar-energy to the ambient to keep the PV module surface temperature always close to the ambient temperature. In addition, this system controls the cleaning period of the module front surface. The results showed a decrease of about 45.5% and 39% in module temperature at front and rear faces, respectively. Consequently, the cooled and surface cleaned module has an efficiency of 11.7% against 9% for the module without cooling and cleaning. Moreover, the maximum output power produced by cooled and cleaned module is 89.4W against 68.4W for non-cooled and non-cleaned module.
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