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Copyright of Przegląd Elektrotechniczny is the property of Przeglad Elektrotechniczny and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The problem of increasing the reliability of transport units during maintenance and repair in the locomotive depot is considered. The transient processes in the power circuit of the DC electric locomotive with traction motors was studied and a calculation scheme of a DC electric locomotive with the series connected traction motors was presented. When considering the magnetization curve linearization, small increments in the form of the system magnetization characteristic were applied. On the base of those results, it was determined that the duration of the transient process in the traction motor windings of the DC electric locomotives equals tt = 3τ. [ABSTRACT FROM AUTHOR]

Power circuits have been introduced in 2012 by Myasnikov, Ushakov and Won as a data structure for non-elementarily compressed integers supporting the arithmetic operations addition and (x , y) ↦ x · 2 y . The same authors applied power circuits to give a polynomial time solution to the word problem of the Baumslag group, which has a non-elementary Dehn function. In this work, we examine power circuits and the word problem of the Baumslag group under parallel complexity aspects. In particular, we establish that the word problem of the Baumslag group can be solved in NC — even though one of the essential steps is to compare two integers given by power circuits and this, in general, is shown to be P-complete. The key observation is that the depth of the occurring power circuits is logarithmic and such power circuits can be compared in NC. [ABSTRACT FROM AUTHOR]

This paper describes the abrasive wear mechanism of dispersed-filler epoxy-based composites, which includes the removal of anti-abrasive filler particles from the total mass of the substance as the matrix wears out. The disturbance of their equilibrium occurs through separation, shear, and rotation, depending on the parameters of the power loading circuit. At the same time, the force required to remove particles from the matrix is determined by their size, shape, spatial arrangement, internal adhesive strength of the particle–matrix system, area of contact with the matrix ("adhesion"), and physical, mechanical, and tribotechnical properties. [ABSTRACT FROM AUTHOR]

Mass of a passenger train and, accordingly, number of cars in its composition is selected based on the amount of passenger traffic on the section, determined by the seasonal demand for transportation in each direction. In one direction of the section serviced by an electric locomotive, the mass of a passenger train may differ several times from the opposite direction, which depends on the destination station of the train and the period of its circulation. At present, in addition to 6-axle electric locomotives of the ChS2T and EP2K series, more powerful 8-axle electric locomotives of the ChS7 series operate in the same schedule for traction of passenger trains on railway sections electrified with direct current with a voltage of 3 kV catenary. All three series of the considered electric locomotives are designed for a maximum operating speed of up to 160 km/h. In this regard, there is a situation with the underutilization of the maximum speed and excess power of the ChS7 electric ocomotives, especially when operating with passenger trains of medium and low weight and a limited speed of 120 km/h. The comparative data on the specific power consumption of the EP2K 6-axle electric locomotives and the ChS7 8-axle electric locomotives operating in the same schedule, presented in the article, indicate the need to find additional reserves for saving the specific power consumption when servicing passenger trains of medium and low weight with ChS7 electric locomotives. The electric locomotive power system includes traction and auxiliary electric machines. The article discusses ways to turn off part of traction motors, which can be carried out with a standard electric locomotive circuit. However, when one section of the electric locomotive is turned off, the power of the four traction motors remaining in operation is not always sufficient to drive a passenger train according to the schedule. Therefore, a variant of improving the power circuit of an electric locomotive in the process of carrying out its overhaul is proposed. This option represents the modernization of the power circuit of the ChS7 electric locomotive when operating on a series-parallel connection with a pair of traction motors disconnected. As a result, the power circuit of the 8-axle electric locomotive operates similarly to the circuit of 6-axle DC electric locomotives with a collector traction drive. The expected savings in specific power consumption can reach 15% in comparison with the operation of an 8-axle electric locomotive ChS7 in normal mode. Switching off one section of the electric locomotive and further running the train on four traction electric motors will reduce the specific power consumption by up to 25%.

In this study, a silicon carbide (SiC) MOSFET driving circuit and its protection circuit applied to high temperature (HT) environment are designed by using commercial off‐the‐shelf discrete components. The proposed driving circuit can work at 200°C with a low driving dissipation. An isolation structure with a transformer is utilised to prevent the control circuits from being disturbed by the power circuit. The high value of output driving voltage VGS is 19 V to ensure the low on‐resistance of SiC MOSFET, while the low value of VGS is −5 V to ensure the SiC MOSFET not be turned on mistakenly. The driving circuit also solves the the contradiction between the BJT switch speed and power dissipation of conventional HT SiC MOSFET driving circuit. The rising time and falling time of the output VGS are reduced greatly, which can increase the performance of SiC MOSFET in high frequency application at a HT. [ABSTRACT FROM AUTHOR]

This study presents a method of chaotification of universal motor drive by selecting appropriate topology of the power circuit and suitably choosing values of circuit components for mixing application. The purpose of chaotification is to improve homogeneity in the mixture and to reduce consumption of time, cost and energy. In particular, the dynamic behaviour of a pulse‐width modulation controlled chopper fed universal motor drive with diode bridge rectifier at the source side has been explored for the occurrence of chaos in the mixer motor. Performance of the drive has been investigated with two different topologies of the filter circuit. The first topology uses a capacitor filter after diode rectifier and the other includes an LC filter at the motor terminals along with source‐side capacitor filter. A systematic methodology for selecting appropriate values of the filter circuit components has been proposed for imparting chaotic motion to the motor load system. A comparative study showing a range of load torque and speed for which sub‐harmonic or chaotic speed oscillation occurs in the motor for both the topologies of filter circuit has also been presented. Computer simulations and results of laboratory experiment performed on a 0.5 hp, 1800‐rpm universal motor validate the proposed design method of the motor drive for the better mixing process. [ABSTRACT FROM AUTHOR]

Higman's group H = 〈 a , b , c , d | b a = b 2 , c b = c 2 , d c = d 2 , a d = a 2 〉 is a remarkable group with large (non-elementary) Dehn function. Higman constructed the group in 1951 to produce the first examples of infinite simple groups. Using finite state automata, and studying fixed points of certain finite state transducers, we show the conjugacy problem in H is decidable for all inputs. Diekert, Laun and Ushakov have recently shown the word problem in H is solvable in polynomial time, using the power circuit technology of Myasnikov, Ushakov and Won. Building on this work, we also show in a strongly generic setting that the conjugacy problem for H has a polynomial time solution. [ABSTRACT FROM AUTHOR]

Pure electric vehicles (PEVs) offer a solution for achieving a zero‐emission transport system. This study presents the work towards the development of a bi‐directional multiport solar‐assisted switched reluctance motor (SRM) drive for PEV applications having battery‐to‐vehicle (B2V), photovoltaic (PV)‐to‐vehicle (PV2V), PV assisted B2V, grid‐to‐vehicle battery charging and PV2V battery charging functions. The power circuit is formed by the combination of a front‐end circuit and a modified‐Miller SRM converter. Battery, PV panel, grid and SRM form the four ports of this multiport drive, which with proper control, provide motoring, braking and charging functions. The dc‐link voltage is fully controllable which improves the machine performance both at higher and lower speeds. During stand‐still conditions, the battery is charged either from the grid at unity power factor or through the PV panel by incorporating the drive components to form an on‐board battery charger, thereby reducing the reliance on charging stations. A fault‐tolerant control is developed to operate the system with desired performance under single and double phase open‐circuit faults. An 8/6 SRM is used for proof of concept and the experimental results confirm the effectiveness of the proposed drive and control strategy. [ABSTRACT FROM AUTHOR]

The existing single‐phase, quasi‐Z‐source inverter (qZSI), photovoltaic (PV) power system with integrated battery energy storage (BES), abbreviated as BES‐qZSI‐PV power system, has several well‐known advantages, but cannot operate at night because there is no PV power input. In this study, a solution to overcome this issue is proposed. First, the power circuit of the conventional BES‐qZSI‐PV topology is modified to allow its operation at both day and night. Then, the system model for the night‐operation mode is built and a qZS network parameters' design method to limit the double‐line frequency harmonic at the dc side is developed. A control strategy to ensure the high‐performance operation of the system at all times, is proposed. Based on an experimental platform of single‐phase BES‐qZSI‐PV power system, three groups of experimental tests with different qZS network parameters and battery voltages are carried out to verify the model and parameters design method by means of comparing the experimental, circuit‐based simulated, and model‐based calculated results. The proposed BES‐qZSI‐PV system performance is experimentally evaluated in steady‐state operation and day‐to‐night transit operation, as well as by the power efficiency curves in day‐ and night‐modes. [ABSTRACT FROM AUTHOR]

To coordinate the damping performance and energy regenerative performance of the energy-regenerative suspension and increase the energy recovery efficiency, an energy-regenerative suspension system with electro-magnetic hybrid actuator was put forward. The mathematical model of the energy-regenerative suspension with electro-magnetic hybrid actuator was established and verified by experiments. The power module circuit and the new mode switching control strategy were designed, and corresponding numerical simulation was carried out for comparison and analysis. The results show that the dynamic performances of energy-regenerative suspension drops by about 4%, while the energy recovery efficiency increases by 13.65%, which means that the energy recovery efficiency of the electro-magnetic hybrid energy-regenerative suspension can be effectively improved when the requirements of certain vehicle ride comfort are satisfied. [ABSTRACT FROM AUTHOR]

A computational experiment was conducted which showed that the controlled electrical parameters of the process can be used to regulate the shape of the metal pool and electrode melting rate. Dependencies between the depth of electrode immersion into the slag pool, average depth of item penetration and uniformity of item penetration relative to average penetration depth were determined. A method was proposed for computation of the depth of electrode immersion into the slag pool by the ratio of currents in CSM. Comparative analysis of the three types of single-loop circuits of the mould connection to the power source was performed, and an optimum circuit for the required criteria of surfacing quality was proposed. [ABSTRACT FROM AUTHOR]

This study discusses the connection of wind farms (WFs) to power system through unified inter‐phase power controller (UIPC) for enhanced transient stability of the power system. The power circuit of the UIPC is based on the conventional inter‐phase power controller (IPC), which its phase‐shifting transforms are substituted by two series converters and one shunt converter. During fault condition, the WF connected through UIPC acts as STATCOM with capability of the active and reactive power control at UIPC connecting point. Based on the UIPC model and low‐voltage ride‐through requirements of the new grid codes, a control system for active and reactive powers control is proposed for enhancement transient stability of power system. The proposed approach is validated in a four‐machine two‐area test system. Power systems computer aided design (PSCAD)/EMTDC simulation results demonstrate that the UIPC provides an effective solution for enhancement of transient stability of power system including WFs. [ABSTRACT FROM AUTHOR]

In this paper, a power-supply circuit for a multipurpose switched reluctance motor with a series commutation buffer is presented. It is shown that a series buffer improves output characteristics of multipurpose switched reluctance motors under supply from a single-phase circuit and also lifts necessity of switching capacitors according to the motor power supply modes.

The transitional processes in shunt circuit of traction engines, which armatures and excitation windings are connected in non-conducting direction as to the flowing power current, are considered in this paper. The changes in the control circuits of braking switch and in the shunt power circuit of traction engines with additional mounting a resistor of 0.5 Ohm are proposed. All this modernization will allow increasing greatly the operation reliability of power circuit of ЭР2Т and ЕПЛ2Т electric locomotives during their service life.

This paper deals with the well-grounded proposals for improving the efficient protection of traction motors from the short circuit and the slip of wheel sets.

Here, we propose an exhaustive theoretical investigation and experimental verification of the false trigger-on phenomenon, which would lead to the interaction between the upper and lower devices during the switching transient, in the zero-voltage-switching (ZVS) full-bridge converter. An equivalent model of the converter, which takes not only the parasitic capacitors of the metal-oxide-semiconductor field-effect transistors into account but also the stray inductances of the main circuit, is presented. Based on the model, a comprehensive study of the false trigger-on phenomenon is carried out. According to the analysis results, the stray inductances of the metal-oxide-semiconductor field-effect transistors have negligible influence on the false trigger-on phenomena since the soft-switching is realized. The false trigger-on phenomenon is induced by the stray inductances of the main circuit. Moreover, the arrangement of the switching sequence would cause significant discriminations in the false trigger-on phenomena because of the specific working mode of the ZVS full-bridge converter. According to the investigation results, optimization methods are presented to suppress the induced voltage. At last, the theoretical investigations are verified by tests of a ZVS full-bridge converter. [ABSTRACT FROM AUTHOR]

Results of simulations of the processes of changing currents and voltages in power circuits of VL10 (VL-10W) locomotives with traction motors, which are connected in series, in cold insulation have been considered. Taking the thermal state of the insulation structures of traction motors of locomotives into account is a new approach in simulations of electrical processes in power circuits. Such a differentiated approach to simulating the electrical processes in power circuits of locomotives became possible when the capacitive components of anchor and pole windings of traction motors in locomotives were studied and taken into account in the equivalent circuits, as well as their temperature dependences. In this work, the results of simulations of the processes of changing currents and voltages in power circuits of VL10 (VL-10W) locomotives during a start from rest in the case of series connection of traction motors with insulation temperature of their anchor and pole windings equal to 20°C. The results of simulations are shown as graphic time dependences of currents and voltages in the main elements of a locomotive power circuit. [ABSTRACT FROM AUTHOR]

The conjugacy problem asks whether two words over generators of a fixed group G are conjugated, i.e., it is the problem to decide on input words x, y whether there exists z such that $$zx z^{-1} =y$$ in G. The conjugacy problem is more difficult than the word problem, in general. We investigate the conjugacy problem for two prominent groups: the Baumslag-Solitar group $$\mathbf{{BS}}_{1,2}$$ and the Baumslag group $${\mathbf{{G}}}_{1,2}$$ (also known as Baumslag-Gersten group). The conjugacy problem in $${\mathbf{{BS}}}_{1,2}$$ is complete for the circuit class $$\mathsf {TC}^0$$ . To the best of our knowledge $${\mathbf{{BS}}}_{1,2}$$ is the first natural infinite non-commutative group where such a precise and low complexity is shown. The Baumslag group $${\mathbf{{G}}}_{1,2}$$ is an HNN-extension of $${\mathbf{{BS}}}_{1,2}$$ . Hence, decidability of the conjugacy problem in $$\mathbf{{G}}_{1,2}$$ outside the so-called 'black hole' follows from Borovik et al. (Int J Algebra Comput 17(5/6):963-997, 2007). Decidability everywhere is due to Beese. Moreover, he showed exponential time for the set of elements which cannot be conjugated into $$\mathbf{{BS}}_{1,2}$$ (Beese 2012). Here we improve Beese's result in two directions by showing that the conjugacy problem in $${\mathbf{{G}}}_{1,2}$$ can be solved in polynomial time in a strongly generic setting. This means that essentially for all inputs, conjugacy in $${\mathbf{{G}}}_{1,2}$$ can be decided efficiently. In contrast, we show that under a plausible assumption the average case complexity of the same problem is non-elementary. Moreover, we provide a lower bound for the conjugacy problem in $${\mathbf{{G}}}_{1,2}$$ by reducing the divisibility problem in power circuits to the conjugacy problem in $${\mathbf{{G}}}_{1,2}$$ . The complexity of the divisibility problem in power circuits is an open and interesting problem in integer arithmetic. We conjecture that it cannot be solved in elementary time because we can show that it cannot be solved in elementary time by calculating modulo values in power circuits. [ABSTRACT FROM AUTHOR]

In order to realize a true WoT environment, a reliable power circuit is required to ensure interconnections among a range of WoT devices. This paper presents research on sensors and their effects on the reliability and response characteristics of power circuits in WoT devices. The presented research can be used in various power circuit applications, such as energy harvesting interfaces, photovoltaic systems, and battery management systems for the WoT devices. As power circuits rely on the feedback from voltage/current sensors, the system performance is likely to be affected by the sensor failure rates, sensor dynamic characteristics, and their interface circuits. This study investigated how the operational availability of the power circuits is affected by the sensor failure rates by performing a quantitative reliability analysis. In the analysis process, this paper also includes the effects of various reconstruction and estimation techniques used in power processing circuits (e.g., energy harvesting circuits and photovoltaic systems). This paper also reports how the transient control performance of power circuits is affected by sensor interface circuits. With the frequency domain stability analysis and circuit simulation, it was verified that the interface circuit dynamics may affect the transient response characteristics of power circuits. The verification results in this paper showed that the reliability and control performance of the power circuits can be affected by the sensor types, fault tolerant approaches against sensor failures, and the response characteristics of the sensor interfaces. The analysis results were also verified by experiments using a power circuit prototype. [ABSTRACT FROM AUTHOR]

A method is developed for reducing the power inverter electrical circuit of fourth order to an electrical network of second order. The reduction is based on the assumption that the output inverter voltage is practically with a sine-wave shape. The normalized form guarantees novelty and versatility of the investigation on one hand and independency in relation to the concrete inverter parameters like output power, supplying voltage and operating frequency on the other. From the whole power network of fourth order for the first time two sub circuits are suggested to be outlined: the output (load) sub circuit and the inverter commutating sub circuit. Both sub circuits of a second order define the parameters of the endmost inverter circuit again of the same order and consequently the mode of operation and parameters of the power inverter itself. The transformation is possible owing to the newly found fact that the frequency dependencies of the output (load) sub circuit can be separated from the dependencies that describe the structural relationships between the two sub circuits. The results from that conversion are of course more accurate when the resonant frequencies of the both sub circuits and the operating frequency do not differ substantially. The suggested approach is useful on order to obtain a simplified engineer method for precise and fast design of large class of static power converters applicable in electronic technology like induction heating and melting. [ABSTRACT FROM AUTHOR]

Copyright of Technical Transactions / Czasopismo Techniczne is the property of Sciendo and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Switching power suppliers are described through a mixed analog/digital model. The analog (nonlinear) part is represented by the power circuit and the digital one by the control driving the (MOSFET) switches. We present a general, efficient, and reliable technique to determine, versus variations of design parameters, 1) the periodic steady-state behavior of these circuits discussing stability, 2) periodic time varying transfer functions, and 3) to straightforwardly evaluate the performances of the controller. The proposed simulation approach resorts to the saltation matrix operator to define fundamental matrix for hybrid dynamical systems. This extends conventional simulation and analysis techniques such as the shooting method, the periodic linear phasor, and the Floquet multipliers evaluation to mixed analog/digital circuits. The effectiveness of the approach, representing an alternative viewpoint with respect to commonly adopted analysis strategies, is shown by designing a version of a voltage regulator module for a computer and by investigating its limits versus its output filtering capacitance. [ABSTRACT FROM AUTHOR]

Copyright of Revista Entramado is the property of Universidad Libre Seccional Cali and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A new driving method for synchronous rectifier (SR) in LLC resonant converter is presented. By adding a zero-crossing noise filter (ZCNF) to the drain and source of the SR FET, the false-triggering of the SR can be effectively eliminated. Moreover, the resistor and the capacitor in the filter can be used as a compensator to solve the duty-cycle loss issue caused by the trace inductance of the MOSFET package. Only three passive components are needed in the proposed filter, which makes it reliable and easy to implement. Simulation and experimental results show that the ZCNF can significantly improve the reliability as well as the efficiency of the power circuit. A prototype of 400 V to 12 V 600-W half-bridge LLC resonant converter is built to verify the advantages of the ZCNF. An efficiency improvement of 0.8% is achieved by the ZCNF. [ABSTRACT FROM AUTHOR]

Power conversion interface for small‐capacity wind power generation system based on permanent‐magnet synchronous generator (PMSG) is proposed in this paper. The proposed power conversion interface will convert the wind power generated from the three‐phase PMSG to a high quality power to inject into the single‐phase utility. This power conversion interface comprises of a power converter and a zero‐sequence transformer set. The power converter is controlled to generate a set of positive‐sequence currents to absorb a real power from the three‐phase PMSG and a set of zero‐sequence currents to pass through the zero‐sequence transformer set to the single‐phase utility. A feed‐forward control is used to control the proposed power conversion interface so as to simplify the control circuit. A simplified maximum power point tracking method is also proposed and incorporated in the control circuit of the power conversion interface to extract the maximum power of the PMSG‐based wind power generation system. Hence, the proposed power conversion interface has the advantages of simplifying both the power circuit and the control circuit. A prototype is developed to demonstrate the performance of the proposed power conversion interface. The experimental results show that the proposed power conversion interface can achieve the expected performance. [ABSTRACT FROM AUTHOR]

A low power system for the ligament balance measuring in Total Knee Arthroplasty is presented in this paper. The system consists two parts: a front-end Ligament Balance Measuring System (LBMS) which is inserted into the knee joint during the operation, and the display part. LBMS is comprised of a sensors array including eight precise force sensors, signal conditioning circuits that support up to 15 force sensors, a sub-threshold microprocessor, power circuits and a 433 MHz RF transceiver for data transmission. The force corresponding to its distribution is transmitted wirelessly and displayed in 3-D in real time with an accuracy of 0.049 N. The signal conditioning circuits, the sub-threshold 8 bit microprocessor and the application specific integrated circuits chip have been designed and fabricated in 0.18 μm CMOS process. The tested resolution is 60.1 μV (1.35 g) with ±100 mV input. The chip can operate under 1.2 to 3.6 V voltage supply for single battery application with 116-160 μA power consumption. The testing results of the microprocessor show that the leakage power is 46 nW and the dynamic power is 385 nW @ 165 kHz with operating voltage of 350 mV. The simulation results show that the power circuits can provide the supply voltage ranging from 0.3 V to 0.6 V for the sub-threshold microprocessor. Experimental results verified the system. Some clinical experiments will be carried out in the future. [ABSTRACT FROM AUTHOR]

Abstract: We prove that the Word Problem in the Baumslag group which has a non-elementary Dehn function is decidable in polynomial time. [Copyright &y& Elsevier]

Converter power circuits and cooling systems have been reviewed. Recommendations are made on how to choose converter circuits, power IGBT modules, and algorithms for motor voltage formation. Converters for a two-axis bogie are compared at a motor power of 1200 kW. A method for creating a unified converter for all types of electric locomotives is shown. [ABSTRACT FROM AUTHOR]

The actual system of functional inspection of electric equipment of subway cars (type 81-717/714) is based on troubleshooting of electric equipment components element-by-element, during manufacturing and repair of subway cars, followed by a test run on the line or a rolling stand. Such elementwise troubleshooting of electric equipment components does not allow evaluation of their interaction within the complex system of start and brake operating modes of subway cars. Thus, car-repair workshops may deliver subway cars with hidden flaws that are difficult to detect. In order to avoid such a situation, a test run of subway cars is carried out. However, this method does not always allow detecting the exact cause of breakdown, since evaluation of the quality of electric equipment functionality is difficult-only the observable features of car movement are checked (smoothness, presence or lack of shoves, intensity of acceleration and braking, behavior of protection units of the traction motors and power circuits). Thus, a necessity arises to carry out additional test runs of subway cars, which leads to an increase of the costs of adjustment and commissioning. This article covers the results of work on improvement of the procedure of electric equipment functional inspection for subway cars (type 81-717/714), which was done in the Vykhino electric engine house. It is offered to check functioning of electric equipment of subway cars in the car-repair workshop using a stationary testing stand by means of simulation of electric equipment operating regimes that correspond to actual conditions at the operating values of current and voltage in power circuits of subway cars. Actual operating regimes of power equipment of subway cars are simulated using a condenser-type energy storage charged in advance using an external power source. Quality inspection of functioning of the subway cars electric equipment is based on analysis of the power circuit current graphs obtained during stand testing. Use of the proposed system of functional inspection of electric equipment reduces labor by 20-30% for adjustment and commissioning of subway cars that underwent rehabilitation repair. [ABSTRACT FROM AUTHOR]