Improved position offset based parameter determination of permanent magnet synchronous machines under different load conditions

© The Institution of Engineering and Technology 2017.This study proposes a novel method for the parameter determination of permanent magnet (PM) synchronous machines under different load conditions. It can identify the total dq-axis flux linkages and also the PM flux linkage separately by the addition of a pair of negative and positive position offsets. It is also noteworthy that the influence of uncertain inverter non-linearity and winding resistance is cancelled during the modelling process, and the experimental results on two different PM synchronous machines show a good agreement with the finite-element prediction results. More importantly, it shows good performance in online tracking the variation of PM flux linkage, which is an important feature for aiding the condition monitoring of PMs, for example, monitoring the temperature of PMs

Comparative study of dual 3‐phase permanent magnet machines with coil span of two slot‐pitches

In this study, the electromagnetic performances of dual 3-phase permanent magnet (PM) machines with coil span of two slot-pitches are comparatively investigated. It mainly focuses on two PM machines with different slot/pole number combinations (Ns/2p), that is, the 24-slot/10-pole and 24-slot/14-pole machines (2p = Ns/2 ± 2). First, winding configurations are illustrated for these two dual 3-phase machines with 30° angle displacement. Then, the winding factor, back electromotive force, average torque, torque ripple, iron and PM losses, short-circuit (SC) current, and PM irreversible demagnetisation are analysed and compared for both machines on the conditions of healthy operation and one set of three-phase fault, that is, SC or open circuit (OC), respectively. The comparative results show that on healthy condition the 14-pole PM machine has a slightly larger torque output. Besides, on 3-phase OC condition, the 14-pole machine also performs better over-rating torque capability. In terms of iron and PM losses, the 10-pole machine has smaller iron losses but larger PM losses than the 14-pole machine. Moreover, on 3-phase SC condition, the 14-pole machine has a significantly lower risk of PM irreversible demagnetisation than the 10-pole machine, although both machines have very similar SC currents. Finally, the 24-slot/10- and 14-pole dual 3-phase PM machines are both prototyped and some tests are carried out for validation. </p

Down-regulation of cytochrome c resulted in the reduction of caspase 3 and caspase-9 activity in AfMNPV-induced Sl-1 cell.

<p>(A) Sl-1 cells treated with dsRNA for different time points, apoptosis was induced with AfMNPV, and then caspase-3 activity was measured at 10 h post-infection.1. Control cells treated alone with AfMNPV; 2. Cells treated with GFP dsRNA and virus; 3. Cells without any treatment; 4. Cells treated with dsRNA, 24 h later, infected by AfMNPV for 10 h; 5. Cells treated alone with dsRNA for 24 h; 6. Cells treated with dsRNA, 48 h later, infected by AfMNPV for 10 h; 7. Cells treated alone with dsRNA for 48 h; 8. Cells treated with dsRNA, 72 h later, infected by AfMNPV for 10 h; 9. Cells treated alone with dsRNA for 72 h. (B) Caspase-9 activity in cytochrome c dsRNA-treated Sl-1 cells after infection with AfMNPV for 10 h, compared with control cells.1. Normal cells; 2. Cells infected with AfMNPV; 3. Cells infected with AfMNPV for 10 h after GFP dsRNA treatment for 48 h; 4. Cells infected with AfMNPV for 10 h after cyt c dsRNA treatment for 48 hr. *, <i>p</i><0.05.</p

Effect of silencing of cytochrome c on apoptosis induced by AfMNPV in Sl-1 cells.

<p>(A) Microscopy image of cells treated with AfMNPV and cyt-c dsRNA. 1. Cells infected with AfMNPV alone for 10 h; 2. Cells infected with AfMNPV for 10 h after treatment with cyt c dsRNA for 24 h; 3. Cells infected with AfMNPV for 10 h after treatment with cyt-c dsRNA for 48 h.; 4. Cells infected with AfMNPV for 10 h after treatment with cyt-c dsRNA for 72 h. (B) Flow cytometric analysis. Sl-1 cells treated with dsRNA for 48 h,and infected with AfMNPV. At 10 h post infection, cells were staining by PI and FITC-Annexin. Apoptosis was analyzed by flow cytometry. (C) Cyt-c dsRNA resulted in the decrease of apoptosis induced by AfMNPV in Sl-1cells. Data were representive for three independent experiments. *, <i>p</i><0.05.</p

Cytochrome c stimulated caspase-3 activity in cell-free extracts.

<p>Caspase-3 activity in the presence of cytochrome c was measured by a flourimetric assay using the substrate Ac-DEVD-AFC. C1: Control untreated with cytochrome c; 0–10 h: caspase-3 activity in samples treated with cytochrome c for different time points; C2: control treated without cytochrome c for 8 h.</p

Transmission electron images of mitochondria in apoptotic cells induced with AfMNPV.

<p>(A) Control cells showing mitochondria had normal ultrastructure with intact cristae and an elongated form; (B) AfMNPV infection for 4 h resulted in change of mitochondria that appeared swollen and rounded; (C) Mitochondria were further swollen and rounded, cristae of which disappeared in cells infected by AfMNPV for 8 h; (D) Mitochondria with swollen and vesicular-swollen morphology in cells infected with AfMNPV for 12 h. Bar = 500 nm.</p

Cytochrome c dsRNA silenced cytochrome c expression in Sl-1 cells.

<p>(A) Identification of recombinant plasmid pLitmus-cytc containing cytochrome c DNA fragment. pLitmus-cytc was digested with BamH I and EcoR I and then analyzed by agarose gel electrophoresis. M1: 1 kb maker, M2: 100 bp maker, S: plasmid DNA products. (B) Electrophoretic analysis of dsRNA transcribed <i>in vitro</i>. pLitmus-cyt c was digested with BamH I and EcoR I respectively and transcribed <i>in vitro</i>, and RNA products were electrophorised on agrose gel. M: 100 bp maker, S: RNA transcription products. (C) Cytochrome c mRNA level after treatment with dsRNA. Sl-1 cells treated with dsRNA for 0, 24, 48, and 72 h, and after inoculated with AfMNPV for 10 h, total RNA in each treatment was isolated. Cytochrome c mRNA was determined by semi-quantitative RT-PCR.</p

Changes of mitochondria in apoptotic cells induced with AfMNPV under confocal microscopy.

<p>(A) Control cells stained with Mito-Tracker Green, showing mitochondrial normal distribution; (B) Infection of AfMNPV caused mitochondria to aggregate at 4 h post-infection; (C) Mito-Tracker Green staining showed a diffusion of fluorescence at 8 h post-infection, suggesting the disruption and depolarization of mitochondria. Bar = 10 <b>µ</b>m.</p

Pathway of apoptosis mediated by cytochrome c in AfMNPV-infected Sl-1 cells.

<p>MPT: mitochondrial permeability transition.</p

Inhibitor of caspase-9 blocked the activation of pro-caspase-3 in AfMNPV-induced Sl-1 cells.

<p>Con: non-infected cells; V: AfMNPV-infected cells; V+Z-LEHD-FMK: AfMNPV-infected cells cultured in complete medium supplemented with inhibitor of caspase-9 (Z-LEHD-FMK).</p