Performance of Vector-Controlled PMSM Drive Without Using Current Sensors

The current sensorless vector-controlled permanent-magnet synchronous motor (PMSM) drive using a single sensor (i.e., speed sensor) is presented in this work. The current sensors are removed, and the estimated currents are used to close the current loop to minimize the drive cost and make it fault-tolerant against current sensor failure. A classical vector-control PMSM drive requires at least three sensors, i.e., two current sensors and one speed/position sensor. This paper presents a new current estimation technique that is free from inverter switching states, an integrator, and differentiator terms. The drive is suitable for retrofit applications, as it does not require any additional hardware. The reference voltages (vds and vqs) are used to estimate the rotor reference frame currents (i.e., iqs and ids). The presented algorithm depends on the stator resistance (Ɍs). The online Ɍs estimation algorithm is used for compensation to overcome the effect of the Ɍs on the estimated currents. The sensitivity analysis for the currents against the speed is verified and presented. The speed loop is closed with actual speed information, which will try to maintain the reference speed under any circumstances. The proposed current sensorless PMSM drive was validated using MATLAB/Simulink and also verified on a hardware prototype. The presented technique was verified for various operation conditions, and some of the extensive results are presented.publishedVersio

Identification of Comamonas species using 16S rRNA gene sequence

A bacterial strain Bz02 was isolated from a water sample collected from river Gomti at the Indian city of Lucknow. We characterized the strain using 16S rRNA sequence. Phylogenetic analysis showed that the strain formed a monophyletic clade with members of the genus Comamonas. The closest phylogenetic relative was Comamonas testosteroni with 95% 16S rRNA gene sequence similarity. It is proposed that the identified strain Bz02 be assigned as the type strain of a species of the genus Comamonas (Comamonas sp Bz02) based on 16S rRNA gene sequence search in Ribosomal Database Project, small subunit rRNA and large subunit rRNA databases together with the phylogenetic tree analysis. The sequence is deposted in GenBank with the accession number FJ211417

Single Current Sensor-Based Speed Sensorless Vector Controlled PMSM Drive

Single current sensor-based speed sensorless vector controlled PMSM (“Permanent Magnet Synchronous Motor”) drive is presented in this paper. Speed, position, and currents are estimated using single current sensor information of 3- $\Phi$ PMSM drive. 2- $\Phi$ currents in the $dq-axes$ are calculated and closed in the loop using $i_{qs}^{\ast }$ and a phase current information obtained from the single current sensor. The proposed method applies to all types of 3- $\Phi$ PMSM; current estimation is independent of machine parameters and inverter switching states. Drive is made speed and position sensorless by estimating using Y-MRAS (Model Reference Adaptive System). Y-MRAS is developed using reference voltages and estimated currents. The speed estimator depends on stator resistance; any variation in it will affect the drive performance. So, stator resistance needs to be estimated online and compensated in the speed estimation technique. Modified P-MRAS technique is used for stator resistance estimation. Here, the drive performance is also validated under stator resistance variation and its compensation. The proposed drive is independent of switching states, integrator terms, and differentiator terms. The single sensor drive reduces the overall cost of the drive and can be implemented into the existing system for sensor condition monitoring and to make the drive fault tolerant against the sensor failure without any extra hardware. The proposed single sensor-based drive is theoretically-modeled and simulated in the MATLAB/SIMULINK platform. The stability of the proposed drive is verified through a stability analysis. It is experimentally validated using a laboratory-developed PMSM drive prototype with a dSPACE-1104 controller board

A Seven Level Fault Tolerant Switched Capacitor Boost Inverter With a Single DC Source

A Fault-Tolerant Multi-Level Inverter (FT-MLI) is essential to ensure power supply continuity for crucial applications. At the same time, the cost and efficiency of MLI is also important for its successful use in the commercial market. The existing seven level FT-MLI topologies demand more than one input DC source, which increases the cost function. This article proposes a single DC source seven level FT-MLI topology with minimum number of switches (IGBT) to reduce the cost function. The proposed FT-MLI topology generates seven level output voltage with 1.5 times voltage boosting. In case of open or short circuit fault on any single or multi switch, the topology continues to operate with five level output voltage using reserved switches. It consists of eight active switches, two diodes, two capacitors, six thermal fuses, and three reserved switches. In comparison to the existing seven level fault tolerant (open circuit and short circuit fault) topologies, the suggested structure requires minimum number of component count. The efficiency and power losses of the proposed structure are analyzed theoretically. The proposed topology has an efficiency of 96 % at an output power of 600 W under healthy condition and 97% at an output power of 272 W under post fault condition. The level shift pulse width modulation approach is used to generate required triggering pulse for the switch during pre-fault and post-fault. The proposed topology is simulated in the MATLAB/Simulink platform and experimentally verified using dSPACE 1104. The response of the output voltage and current during the transition from pre-fault to post-post fault for each switch fault are presented

Clinical outcome in cases of hypertensive intra-cerebral haemorrhage in relation to size of haemorrhage

Introduction: Stroke is amongst the leading causes of death exceeded only by heart disease and cancer. Those who survive are usually left with permanent disability. Cerebral infarction is responsible for about 80 percent of all strokes, primary intra-cerebral haemorrhage for 10 percent, subarachnoid haemorrhage for 5 percent and 5 percent cases are due to uncertain causes. Predictors of prognosis in primary intraparenchymal haemorrhage have been evaluated in numerous studies. Objective: To observed the effect of different sizes of hematoma and utilizing them, if feasible as a marker of prognostic significance. Material and methods: In this study we observed 60 patients from the time of admission till 30th day in various wards of Department of Medicine RIMS with hypertensive intra-cerebral haemorrhage, during the period of 2008-2009. A simple method of measuring the volume of haematoma (in cc) on the CT scan is by using the following formula: A*B*C A = longest diameter of the haematoma (in cm.), B = Diameter perpendicular to A (in cm.), C = Height (in cm) which is measured by No. of slices showing the haematoma x thickness of each slide. Result: Total 60 patient were taken into study out of which 33(55%) were alive and 27(45%) were dead in 30 days follow up. In our study, 38 were male and 22 were female out of 38 male 22(66.66%) were alive and 16 (59.2%) dead and in 22 female 11(33.33%) were alive and 11 (40.7%) were dead. Outcome with volume of ICH using the χ2 had shown significant correlation (p < 0.005) with GCS at the time stroke onset (P<0.01), IVH/VE (P<0.01), midline shift test (P<0.01), B.P. at the time of admission (P<0.01). Conclusion: In these study patients with hematoma volume exceeds 60 cm3, the mortality was 100%. Mean volume of hematoma in our study was 35.21 cm3

A detailed full-order discrete-time modeling and stability prediction of the single-phase dual active bridge DC-DC converter

The standard methodology to obtain the model of a power electronic converter is achieved by averaging the state-space dynamics of the converter's state variables. But the average of the transformer current is null over a switching cycle in the resonant dc-dc converter. Therefore, the conventional method is not suitable for resonant converters, including the phase-shifted bidirectional dual active bridge (PSBDAB) converter. The two-time scale discrete-type models can resolve the problem associated with the standard state-space averaging methodology. The time-scale segregates the dynamics of the PSBDAB converter into fast and slow state variables, which can be modeled separately and eases the analysis of the PSBDAB converter. The effect of the core-loss of the inductor, dead-time of the semiconductor devices, output filter capacitor's equivalent series resistance, semiconductor on-resistance, and the transformer copper loss components are included in the model to improve its steady-state and dynamics characteristics. Moreover, the stability analysis using a bifurcation diagram is carried out for the digitally controlled closed-loop of the system. Furthermore, the critical gain for the stable region with variations in the circuit parameters like load resistance, circuit equivalent inductance, and voltage demand is extensively studied. The modeling and stability analysis is validated in the simulation and experimental setup. The results verify that the proposed method accurately predicts the stable region with variations in the system circuit parameters. Thus this study provides a guide to select and tune the controller parameter to ensure the converter operates within the boundaries of the stable region.Published versionThis work was supported by Princess Nourah bint Abdulrahman University Researchers Supporting Project PNURSP2022R79, Princess Nourah bint Abdulrahman University, Riyadh

Modulation of fungal virulence through CRZ1 regulated F-BAR-dependent actin remodeling and endocytosis in chickpea infecting phytopathogen Ascochyta rabiei.

Polarized hyphal growth of filamentous pathogenic fungi is an essential event for host penetration and colonization. The long-range early endosomal trafficking during hyphal growth is crucial for nutrient uptake, sensing of host-specific cues, and regulation of effector production. Bin1/Amphiphysin/Rvs167 (BAR) domain-containing proteins mediate fundamental cellular processes, including membrane remodeling and endocytosis. Here, we identified a F-BAR domain protein (ArF-BAR) in the necrotrophic fungus Ascochyta rabiei and demonstrate its involvement in endosome-dependent fungal virulence on the host plant Cicer arietinum. We show that ArF-BAR regulates endocytosis at the hyphal tip, localizes to the early endosomes, and is involved in actin dynamics. Functional studies involving gene knockout and complementation experiments reveal that ArF-BAR is necessary for virulence. The loss-of-function of ArF-BAR gene results in delayed formation of apical septum in fungal cells near growing hyphal tip that is crucial for host penetration, and impaired secretion of a candidate effector having secretory signal peptide for translocation across the endoplasmic reticulum membrane. The mRNA transcripts of ArF-BAR were induced in response to oxidative stress and infection. We also show that ArF-BAR is able to tubulate synthetic liposomes, suggesting the functional role of F-BAR domain in membrane tubule formation in vivo. Further, our studies identified a stress-induced transcription factor, ArCRZ1 (Calcineurin-responsive zinc finger 1), as key transcriptional regulator of ArF-BAR expression. We propose a model in which ArCRZ1 functions upstream of ArF-BAR to regulate A. rabiei virulence through a mechanism that involves endocytosis, effector secretion, and actin cytoskeleton regulation