Modelling and indirect field‐oriented control for pole phase modulation induction motor drives

In the recent days, for the traction and electric vehicle (EV) applications, multiphase machines with pole phase modulation (PPM) technique have been proposed. The smoother operation during pole changeovers as well as steady-state operations is a significant constraint while adopting the PPM-based multiphase induction motor (PPMIM) drives for EV and traction applications. So, in this paper, the PPMIM dynamic model and associated vector control are proposed for attaining a smoother operation of the machine. The machine modelling equations and transformation matrices are implemented in an arbitrary reference frame by considering the different pole phase combinations. Based on the modelling equations, the indirect field-oriented control (IFOC) is proposed for PPMIM drives by reflecting the associated changes in parameters for different pole phase modes. In the IFOC, for regulating the d-axis and q-axis current components, single PI control loops have been implemented for all pole-phase combinations. The proposed IFOC scheme is robust and applicable for adopting any type of pulse width modulation. The experimental, as well as simulation results, are given to illustrate the potentiality of the proposed dynamic model and IFOC. The PPMIM machine performance during the steady state as well as pole changeovers in different pole phase modes are analyzed and associated. Simulation and experimental results are presented

Non-Isolated DC-DC Power Converter with High Gain and Inverting Capability

As the voltage gain of converter increases with the same ratio, the current gain also increases, this increase in current gains will affect the size of the input and the output capacitor. To reduce the ripple in the input current with simultaneous decreasing the input current ripple, a novel current fed interleaved high gain converter is proposed by utilizing the interleaved front-end structure and Cockcroft Walton (CW)-Voltage Multiplier (VM). The 'current fed' term is used because, in proposed circuitry, all the capacitors of CW-VM are energized by a current path via inductors of the interleaved structure. The proposed converter can be applied as an input boost up the stage for low voltage battery energy storage systems, photovoltaic (PV) and fuel cell (FC) based DC-AC applications. The anticipated topology consists of the two low voltage rating switches. The main benefits of the anticipated converter configuration are the continuous (ripple free) input current, high voltage gain, reduced switch rating, high reliability, easy control structure and a high percentage of efficiency. The proposed converter's working principle, mathematical based steady-state analysis, and detailed component design are discussed. The parasitic of the components has been considered in the analysis to show the deviation from the ideal cases. A detailed comparison with the other available converters is presented. The experimental results of the 300W prototype are developed to confirm the performance and functionality of the anticipated DC-DC converter.This work was supported in part by the Qatar University-Marubeni Concept to Prototype Development Research Grant through the Qatar University under Grant MCTP-CENG-2020-2, and in part by the Qatar National Library, Doha, Qatar. The statements made herein are solely the responsibility of the authors.Scopu

A New Family of Step-up Hybrid Switched-Capacitor Integrated Multilevel Inverter Topologies with Dual Input Voltage Sources

In the low voltage based renewable systems like PV and Fuel cell applications, the step-up of the output voltage to drive the loads is essential. For this, the integration of switched-capacitor (SC) units with the dc-ac converters will have the potential advantages like improved efficiency, optimal switching devices, small size of passive elements (L and C) as compared with traditional two-stage conversion system (dc/dc converter and dc/ac converter). This paper focuses on a new family of step-up multilevel inverter topologies with switched capacitor integration with dual input voltage sources. With the flexibility of 2 dc sources and switching capacitor circuits, four different topologies have been suggested in this paper with features of high voltage gain, reduced component count, reduced voltage stress and self-voltage balancing of the capacitor while achieving a higher number of levels. A detailed analysis of proposed multilevel inverters has been analyzed with the symmetrical and asymmetrical mode of operations and the associated gain, the number of levels, and other performance indices are presented. An in-depth study of all the topologies has been accomplished in this paper with several comparative studies in terms of components count, voltage gain and cost. The effectiveness and practicability of the suggested topology with 13 level output voltage has been explained by the experimental results obtained from a scale down prototype.Scopu

7L-SCBI topology with minimal semiconductor device count

In this work, a seven-level switched capacitor boost inverter (7L-SCBI) is proposed with minimal resource count. The proposed inverter requires only eight switches and two capacitors to generate a seven-level voltage. The proposed 7L-SCBI is capable of generating a multilevel voltage as well as boost the input DC-link voltage up to 1.5 times with a reduced blocking voltage of switches and capacitors. The comparison in terms of efficiency and device count with other switched capacitor topologies is presented in detail. The performance validation of the proposed 7L-SCBI is done with the help of a laboratory prototype. reserved.This publication was made possible by Qatar University-Marubeni Concept to Prototype Development Research grant # [M-CTP-CENG-2020-2] from the Qatar University. The statements made herein are solely the responsibility of the authors.Scopu

Phylogeography of mtDNA haplogroup R7 in the Indian peninsula.

BACKGROUND: Human genetic diversity observed in Indian subcontinent is second only to that of Africa. This implies an early settlement and demographic growth soon after the first 'Out-of-Africa' dispersal of anatomically modern humans in Late Pleistocene. In contrast to this perspective, linguistic diversity in India has been thought to derive from more recent population movements and episodes of contact. With the exception of Dravidian, which origin and relatedness to other language phyla is obscure, all the language families in India can be linked to language families spoken in different regions of Eurasia. Mitochondrial DNA and Y chromosome evidence has supported largely local evolution of the genetic lineages of the majority of Dravidian and Indo-European speaking populations, but there is no consensus yet on the question of whether the Munda (Austro-Asiatic) speaking populations originated in India or derive from a relatively recent migration from further East. RESULTS: Here, we report the analysis of 35 novel complete mtDNA sequences from India which refine the structure of Indian-specific varieties of haplogroup R. Detailed analysis of haplogroup R7, coupled with a survey of approximately 12,000 mtDNAs from caste and tribal groups over the entire Indian subcontinent, reveals that one of its more recently derived branches (R7a1), is particularly frequent among Munda-speaking tribal groups. This branch is nested within diverse R7 lineages found among Dravidian and Indo-European speakers of India. We have inferred from this that a subset of Munda-speaking groups have acquired R7 relatively recently. Furthermore, we find that the distribution of R7a1 within the Munda-speakers is largely restricted to one of the sub-branches (Kherwari) of northern Munda languages. This evidence does not support the hypothesis that the Austro-Asiatic speakers are the primary source of the R7 variation. Statistical analyses suggest a significant correlation between genetic variation and geography, rather than between genes and languages. CONCLUSION: Our high-resolution phylogeographic study, involving diverse linguistic groups in India, suggests that the high frequency of mtDNA haplogroup R7 among Munda speaking populations of India can be explained best by gene flow from linguistically different populations of Indian subcontinent. The conclusion is based on the observation that among Indo-Europeans, and particularly in Dravidians, the haplogroup is, despite its lower frequency, phylogenetically more divergent, while among the Munda speakers only one sub-clade of R7, i.e. R7a1, can be observed. It is noteworthy that though R7 is autochthonous to India, and arises from the root of hg R, its distribution and phylogeography in India is not uniform. This suggests the more ancient establishment of an autochthonous matrilineal genetic structure, and that isolation in the Pleistocene, lineage loss through drift, and endogamy of prehistoric and historic groups have greatly inhibited genetic homogenization and geographical uniformity.RIGHTS : This article is licensed under the BioMed Central licence at http://www.biomedcentral.com/about/license which is similar to the 'Creative Commons Attribution Licence'. In brief you may : copy, distribute, and display the work; make derivative works; or make commercial use of the work - under the following conditions: the original author must be given credit; for any reuse or distribution, it must be made clear to others what the license terms of this work are

The Influence of Natural Barriers in Shaping the Genetic Structure of Maharashtra Populations

BACKGROUND: The geographical position of Maharashtra state makes it rather essential to study the dispersal of modern humans in South Asia. Several hypotheses have been proposed to explain the cultural, linguistic and geographical affinity of the populations living in Maharashtra state with other South Asian populations. The genetic origin of populations living in this state is poorly understood and hitherto been described at low molecular resolution level. METHODOLOGY/PRINCIPAL FINDINGS: To address this issue, we have analyzed the mitochondrial DNA (mtDNA) of 185 individuals and NRY (non-recombining region of Y chromosome) of 98 individuals belonging to two major tribal populations of Maharashtra, and compared their molecular variations with that of 54 South Asian contemporary populations of adjacent states. Inter and intra population comparisons reveal that the maternal gene pool of Maharashtra state populations is composed of mainly South Asian haplogroups with traces of east and west Eurasian haplogroups, while the paternal haplogroups comprise the South Asian as well as signature of near eastern specific haplogroup J2a. CONCLUSIONS/SIGNIFICANCE: Our analysis suggests that Indian populations, including Maharashtra state, are largely derived from Paleolithic ancient settlers; however, a more recent (∼10 Ky older) detectable paternal gene flow from west Asia is well reflected in the present study. These findings reveal movement of populations to Maharashtra through the western coast rather than mainland where Western Ghats-Vindhya Mountains and Narmada-Tapti rivers might have acted as a natural barrier. Comparing the Maharastrian populations with other South Asian populations reveals that they have a closer affinity with the South Indian than with the Central Indian populations

Distributed Short-Pitch Winding for Multi-Phase Pole-Phase Modulated Induction Motor Drives

In multiphase induction motors the number of slots per pole per phase comes down due to the higher number of phases, which results the airgap MMF per phase closer to square wave. In addition, as the number of poles increases the space harmonics will increase further in Pole-phase modulated induction motor drives (PPMIM) drives. To address this issues, in this paper a distributed short pitch winding (DSPW) is proposed for PPMIM drives. In DSPW, the number of conductors per phase are distributed over three stator slots that will generate the multi-stepped MMF wave in airgap as compared to concentrated winding. Because of this, the space harmonics in the airgap as well as the harmonics in induced EMF will come down, which improves the performance of the drive. The PPMIM drive with proposed DSPW, is capable to operate in 9-phase 2-pole mode and 3-phase 6-pole mode without changing the stator winding connections. A 5hp, nine-phase PPMIM drive with the proposed DSPW is designed by using Ansys Maxwell 2-D FEM tool. The power circuit is designed in Simplorer environment (associated tool for Maxwell 2-D) for co-simulating the Maxwell model of PPMIM drive. Moreover, the torque ripple percentage of PPMIM drive for both concentrated winding as well as for distributed winding has been compared. The proposed drive will offer the wider range of speed and torques which is best suitable for traction and ship propulsion applications

Linear Modulation Range and Torque Ripple Profile Improvement of PPMIM Drives

The pole phase modulated induction motor (PPMIM) drives facilitates the extended range of speed-torque characteristics, which is an essential requirement for traction and electric vehicle applications. For getting the wider speed-torque variations, 15- $\Phi$ PPMIM drive is analyzed, which is capable to operate at 2-pole 15-phase, 6-pole 5-phase and 10-pole 3-phase modes. In these pole phase operations, in high phase and low pole mode of operation, the increment in the linear modulation range with SVPWM is not significant. In the low phase and high pole mode of operation, there will be higher torque ripples due the higher magnitude of space harmonics. In this paper, these issues are addressed by using carrier phase shifted space vector pulse width modulation (CPS-SVPWM) and phase grouping concepts. In low pole operation, the linear modulation is enriched by using conventional 3- $\Phi$ SVPWM to drive 15 phase machine by appropriately reorganizing the phase winding connections. Similarly, in 6-pole 5-phase mode of operation the linear modulation range of PPMIM drive is enriched by using 5- $\Phi$ SVPWM. It is known that in high pole mode of PPMIM drive operation each effective phase is formed by the multiple number of equal voltage potential coils (EVPC), which are electrically in phase. The carriers of these EVPCs per phase are phase shifted by an appropriate angle to minimize the harmonics in the effective phase voltage, which results in better torque ripple profile. In addition, the detailed comparison of three possible different CPS-SVPWM's are presented, with their pros and cons for selecting the proper carrier phase shift angle. The performance of the proposed scheme has been validated by Ansys Maxwell 2-D as well as laboratory prototype on 5hp, 15- $\Phi$ PPMIM drive