Parallel-Connected Multiphase Multidrive Systems With Single Inverter Supply

Multi-phase machines possess additional degrees of freedom, which can be utilised to control other machines within a multi-motor drive system. The stator windings of the multi-phase machines can be connected in series in such a manner as to enable independent control of each machine using vector control principles, although the complete multi-motor drive system is supplied from a single multi-phase voltage source inverter (VSI). One shortcoming of the series arrangement is the need to bring out to the terminal box of an n-phase machine both beginnings and endings of each phase. Parallel connection of machines would circumvent this shortcoming, since the machines can have the neutral point connected within the machine. This paper therefore discusses such a parallel connection of two five-phase machines. The drive configuration and a suitable control scheme are detailed and verification of the concept is provided by simulation. Dynamic model in the stationary reference frame is given and equivalent circuit representation of the parallel-connected five-phase two-motor drive system is developed. It is shown that, due to orthogonal relationship of the two planes that are used for independent control of the two machines, phasor approach can be applied at each of the two fundamental frequencies used to control the two machines. The paper finally explains that, although parallel multi-phase multi-motor drives are feasible and in principle offer the same quality of dynamic performance as series-connected multi-phase multi-motor drive systems, they do not hold a real prospect for industrial applications

An assembly accuracy analysis approach of mechanical assembly involving parallel and serial connections considering form defects and local surface deformations

An efficient control of a series connected two-synchronous motor 5-phase with non sinusoidal EMF supplied by a single 5-leg VSI: Experimental and theoretical investigations

To study the heating performance of a solar-assisted cold-water phase-change-energy heat pump system, its heating performance under series and parallel connections is simulated for a community in Harbin, the influence of ice thickness on the different operation modes is analyzed, and the economy of the system is calculated for series and parallel connections in this paper. The results show that the water supply temperature is higher and more uniform in the parallel operation, and more terminal heat is supplied; the ice thickness has more of an influence on the series connection compared to the parallel connection; and the dynamic payback period is 6.72 years for the series connection and 7.28 years for the parallel connection. This case study can serve as a guide for practical engineering application projects and act as a reference for heating and economic data for the promotion of this heat pump system.

Extracorporeal membrane oxygenation (ECMO) is an important rescue therapy method for the treatment of severe hypoxic lung injury. In some cases, oxygen saturation and oxygen partial pressure in the arterial blood are low despite ECMO therapy. There are case reports in which patients with such instances of refractory hypoxemia received a second membrane lung, either in series or in parallel, to overcome the hypoxemia. It remains unclear whether the parallel or serial connection is more effective. Therefore, we used an improved version of our full-flow ECMO mock circuit to test this. The measurements were performed under conditions in which the membrane lungs were unable to completely oxygenate the blood. As a result, only the photometric pre- and post-oxygenator saturations, blood flow and hemoglobin concentration were required for the calculation of oxygen transfer rates. The results showed that for a pre-oxygenator saturation of 45% and a total blood flow of 10 L/min, the serial connection of two identical 5 L rated oxygenators is 17% more effective in terms of oxygen transfer than the parallel connection. Although the idea of using a second membrane lung if refractory hypoxia occurs is intriguing from a physiological point of view, due to the invasiveness of the solution, further investigations are needed before this should be used in a wider clinical setting.

BATTERIES | Parallel and Series Connections

This paper analyzes a six-phase two-motor drive, consisting of a six-phase voltage-source inverter (VSI), a six-phase induction machine, and a three-phase induction machine. Stator windings of the two machines are connected in series in an appropriate manner. This enables full decoupling of the dynamics of the two machines by means of vector control. Detailed mathematical modeling of the system is performed and the set of d-q equations, describing the two machines connected in series to a six-phase VSI, is developed. The resulting model clearly shows the possibility of independent vector control of the two machines, although a single VSI is used as the supply. An experimental rig is constructed and existence of the decoupled dynamic control of the two machines supplied from a single VSI is fully verified by extensive experimental testing.

Multiphase machines are AC machines characterized by a stator winding composed of a generic number n of phases. In today’s electric drive and power generation technology, multiphase machines play an important role for the benefits they bring compared to traditional three-phase ones (Levi, 2008; Levi et al., 2007). Such benefits have been widely highlighted by existing literature (Levi et al., 2007) and are mainly related to: an increased fault tolerance; higher power ratings achieved through power segmentation; enhanced performance in terms of efficiency and torque ripple. The use of multiphase machines is spreading both in small-power safety-critical applications as well as in very high-power industrial drives (Tessarolo et al., 2010), in electric-propulsion drives (Castellan et al., 2007) and power generation systems (Sulligoi et al., 2010). Regardless of whether they are used as motors or generators, multiphase electrical machines are almost always connected to power electronics systems (inverters for motors, rectifiers for generators), which interface them to the electric grid (Sulligoi et al., 2010; Castellan et al. 2008). Therefore, if the dynamic behaviour of a multiphase machine is to be predicted through simulations in the design and development stage, it is essential to do this by means of system-level simulations, where not only the electric machine is included, but also the power electronics and control systems that interact with it. Such a system-level simulation approach makes it difficult to use Finite-Element (FE) methods due to the complexity of the domain to be modelled and to the well-known computational heaviness of time-stepping FE simulations. Conversely, lumped-parameter models, to be implemented in the Matlab/Simulink environment, may provide designers with a powerful mean of analysis and investigation, provided that all the system components to be studied are modelled with an adequate level of accuracy and completeness. As concerns power electronics systems usually interfaced to multiphase machines, whether operating as motors or generators, the Matlab/Simulink environment offers wide and complete libraries where the designer can find reliable pre-defined blocks (for electronic switches, snubbers, diodes, etc.) to be used in building the application-related apparatus models. The same pertains to control and regulation blocks, which can be built up directly based on their transfer functions and logics. A possible criticality can be encountered when it comes to build the multiphase machine model. In fact, no predefined blocks are presently available in the Matlab/Simulink environment for this purpose. On the other side, building a dedicated user-defined machine

Rod-type metal corrosion probes based on electromechanical impedance (EMI) technique can quantitatively assess the amount of corrosion, which have a promising application in pipeline corrosion monitoring and have received much more attention. In the field of structural health monitoring, the EMI technique based on series and parallel connections has been widely studied and is very promising, but it is yet to be used in the probe design. In this work, a kind of novel metal corrosion probe with two piezoelectric elements in series and parallel connections was proposed, and its performance was investigated comprehensively by combining theoretical analysis with experiment research. Theoretical models of the proposed probe in the longitudinal vibration mode for both series and parallel connections were established, and verified by the experimental results. Influences of the thicknesses of piezoelectric layer and ceramic layer on the probe performance were analyzed. Artificial quantitative corrosion tests and accelerated corrosion tests were designed to evaluate the quantitative corrosion monitoring capacity. Temperature sensitivity tests were conducted to study the temperature dependence. The wireless impedance measurement was performed to confirm the online monitoring ability. Comparisons for the probe performance between the series and parallel connections were also presented. This work provided a comprehensive understanding for this kind of novel probe, which is beneficial to develop low-cost, high-precision, high-stability pipeline corrosion real-time monitoring technology.

The objective of this study is to explore the harvest maximum output changes occurs in piezoelectric transducer when connected in different configuration to produce highest electricity consumption and generate sound energy harvesting system. Acoustic energy is a type of environmental energy source that can be extracted and converted into electrical energy for small-scale energy applications. In this study, the corresponding load resistance for single piezoelectric transducer is 4.5 k$\Omega$, together with a constant vibration source at a frequency of 68 Hz and a 1-g acceleration. The performance of output voltage and power of piezoelectric are evaluated and the optimum output is measured by depending on the connection of the piezoelectric transducer arrangement into series, parallel and series, and parallel which stimulated using Proteus software. The experiment result presented that, when have single piezo, 5 piezo connected in series, and 5 piezo connected in parallel, the output powers are 1.664 mW, 1.671mW and 7.676 mW, respectively. During the combination series and parallel connections, the output power of 3S1P piezo increases to 5.05mW. In a parallel configuration, the output voltage that produced is much higher than a piezoelectric transducer arrangement connected in series connection. The piezoelectric transducer that connected in parallel configurations increases its voltage output from 2.83 V to 13.05 V with the same polarity. The arrangement of piezoelectric transducer in parallel configuration is affordable, with its higher production of a higher power output compared to the arrangement of piezoelectric transducer in series connection. Whereas in terms of power output, the maximum power remains constant in the range of 1.665 to 1.671 mW when three transducers are in series configuration connection with the same polarity. In conclusion, the proper implementation of the piezoelectric array configuration is needed in order to operate the minimum energy for low load devices and promise to accomplish generated optimum power output in harvester system.

Experimental and numerical analysis of oily wastewater treatment using low-cost mineral adsorbent in a single and multi-fixed bed column

The present study examined optimized anodic electrode materials microbial fuel cells (MFCs) with Jashore Municipal Wastewater (JMW) as substrate in series and parallel connections. Three anodic materials, Iron plate (Fe), Carbon felt (CF), and Graphite rod (GR), were used to get green energy from waste biomass in microbial fuel cells. The output voltage, current, and power density of MFC were measured to investigate the preeminent anodic electrode material. The optimized anodic electrode material was Fe owing to high voltage generation followed by CF and GR. Results further indicated that the output voltage increased, but current density, as well as power density, decreased in series connection due to the increase of internal resistance compared to parallel at Fe-Cu combination. The maximum voltage, current density, and power density in series connection were 2238 mV, 79.98 mA/m2, and 108.850 mW⁄m2, respectively. On the other hand, in parallel connection, those values were 793 mV, 248.272 mA/m2, and 115.943 mW⁄m2, respectively. Most small electrical devices need high currents rather than high voltage imply parallel connections are preferred in this regard. Moreover, Fe-Cu combination is better to remove (87%) organic matter regarding COD removal efficiency from wastewater of MFCs.

<italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Contribution:</i> A new operational definition of series connections is given based on elements belonging to the same two meshes, which is properly dual to the usual definition of parallel elements being connected to the same two nodes. Furthermore, computer-based exercises have been developed and tested to teach students about such connections in gateway linear circuits courses, using color coding of nodes and meshes as a pedagogical device. <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Background:</i> Series and parallel connections are a crucial but difficult concept. Existing textbooks give them limited attention, resulting in later difficulties learning circuit analysis. <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Research Questions:</i> RQ1: Can an improved definition of series elements aid student understanding and student satisfaction? RQ2: Can a computer-based “game” lead to effective mastery and student satisfaction at a wide range of institutions, including minority-serving ones? <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Methodology:</i> Standard and new definitions were elaborated in a multiple-choice tutorial. A game was developed focusing on identifying series and parallel connections, with color coding of both nodes and meshes. Student learning was assessed over eight years using pretest and posttest in 14 varied institutions. Student opinions were assessed using several types of surveys. <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Findings:</i> Strong learning gains were observed every semester from built-in pretest and posttest, with average scores of 28% and 87%, respectively. Large improvements were observed at every institution including five minority-serving ones. The posttest score is increased by a statistically significant amount after introducing the new definition of series elements. Students preferred the new definition of series and recommended its use, and very strongly endorsed color coding.

In this paper, a standalone solar photovoltaic (SPV) power generating system is designed and modeled using a Cuk dc-dc converter and a single phase voltage source inverter (VSI). In this system, a dc-dc boost con- verter boosts a low voltage of a PV array to charge a battery at 24 V using a maximum power point tracking control algorithm. To step up a 24 V battery voltage to 360 V dc, a high frequency transformer based isolated dc-dc Cuk con- verter is used to reduce size, weight and losses. The dc voltage of 360 V is fed to a single phase VSI with unipolar switching to achieve a 230 Vrms, 50 Hz ac. The main objectives of this investigation are on efficiency improve- ment, reduction in cost, weight and size of the system and to provide an uninterruptible power to remotely located con- sumers. The complete SPV system is designed and it is modeled in MATLAB/Simulink. The simulated results are presented to demonstrate its satisfactory performance for validating the proposed design and control algorithm.

Decoupling control of two-motor dual three-phase permanent-magnet synchronous motor (PMSM) series-connected system can be realized by using proper phase transposition rules with a single supply from a six-phase voltage source inverter (VSI), which solved the control problem of two motors in series. Since the traditional two-vector SVPWM strategy, which is commonly used in three-phase system, exists 5 th and 7 th harmonics in x-y plane, making it hard to realize decoupling control of two-motor dual three-phase PMSM series-connected system. Meanwhile, the DC bus voltage utilization of carrier-based PWM strategy is lower. Thus one method, which adopted a TBTSB-SVPWM strategy with two modulators, was proposed in this paper. It ensures the inverter output voltage only contains two kinds of fundamental components required by the two seriesconnected motors with a single VSI, making it possible to realize decoupling control of two-motor dual three-phase PMSM series-connected system. Simulation results indicate that there is no influence on the other motor while the speed/load of any one motor changed, achieving the decoupling control of series-connected system, and the feasibility and validness of the proposed approach are verified.