Search

This paper aims to combine the state-of-the-art parameter-adaptation and state-estimation techniques to realize an adaptive and sensorless interior permanent magnet synchronous machine (IPMSM) drive that offers robust performance across the full speed range even in the presence of temperature-variations. Recursive prediction error based Online Parameter Estimator (OPE) accompanied by a gain-scheduler adapts temperature-sensitive motor parameters, i.e. the stator resistance (R s ) and permanent magnet flux linkage ( $\Psi_{\mathrm{m}}$ ) in the lower and higher speed regions respectively. The Active Flux Observer (AFO) and the Pulsating sqUare-wave Voltage Injection (PUVI) based saliency tracking method are adopted to estimate the rotor position in the higher and lower speed regions respectively. The OPE augments the performance of the AFO across a large part of the speed-range and the use of PUVI-based technique eliminates the potential precision-compromise of the estimated position due to the gain-scheduler in the low-speed region. Zynq System on Chip (SoC) based Embedded Real-Time Simulator (ERTS) is used to demonstrate the concepts, in which the drive control and estimation algorithms are programmed in its processor system and the drive hardware is modeled in its Field-Programmable Gate Array (FPGA).

Online adaptation of temperature-sensitive motor parameters is of significance for the electric drives in reliability-critical applications. Recursive prediction error method (RPEM) is widely used for this purpose. Gauss-Newton Algorithm (GNA), a prediction-error-gradients based algorithm, is adopted in this paper to find RPEM-gains for the parameter identification. This paper first investigates the simultaneous identifiability of permanent magnet flux linkage ( $\Psi_{\mathrm{m}}$ ), and stator resistance (Rs) of interior permanent magnet synchronous machine (IPMSM) using both nonlinear observability theorem and RPEM. Subsequently, GNA is analyzed for its tracking capability, speed of convergence, need of gain-scheduling and computational demand in comparison to stochastic gradient (SGA), another algorithm of the same class, using steady and dynamic state simulations.

In this paper, a method is proposed to improve the performance of a mechanical transducer-less control of an interior permanent magnet synchronous machine (IPMSM) with use of a dedicated online parameter estimator (OPE). The active flux observer is employed for position estimation, along with the proposed OPE which displays high sensitivity to parameter-discrepancies, that its parameter adaptation algorithm (PAA) takes advantage of. The temperature-sensitive parameters are adapted in different speed ranges by scheduling the adaptation-gains for optimal performance. The simulation results show that the proposed method improves the torque and speed control of the drive across the torque-speed plane particularly in the presence of varying parameters. © 2020 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.

A method for online adaptation of electric parameters of a rotating machine is proposed herein. The concept adopts the recursive prediction error method (RPEM) for parameter adaptation, that exploits the prediction-error gradient functions (Ψ T ) With the aim of setting a general framework for the cause, the method is systematically demonstrated for online identification of permanent magnet flux linkage (Ψ m ) and stator-winding resistance (R s ) of an interior permanent magnet synchronous machine (IPMSM). Additionally, an experiment to estimate R s at the start-up is presented. The gain-matrix is identified using the stochastic gradient algorithm (SGA). Simulation results validate the rapid convergence performance, adaptability and tuning flexibility of the proposed method. © 2020 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.

A 73-year-old man with an 8-week history of angina underwent an exercise tolerance test at the rapid access clinic, which indicated inducible ischaemia and he was subsequently referred for angiogram. His angiogram demonstrated no coronary pathology. It was later discovered that bloods taken on the day of the procedure showed a haemoglobin of 54 g/L (130–180 g/L). His haemoglobin used to book the angiogram 3 months before was 143 g/L. Following angiogram, a mass was identified in the right iliac fossa and CT scan confirmed a caecal tumour. The patient ultimately underwent a curative right hemicolectomy as an outpatient. The case is a reminder of the importance of basic preangiogram investigations, in particularly a full blood count, to rule-out angina secondary to anaemia through a low haemoglobin. Most importantly, it also questions when the appropriate time is for these investigations to be carried out, prior to coronary angiography.

Background One of the most important components of suicide prevention strategies is to target people who repeat self-harm as they are a high risk group. However, there is some evidence that the incidence of repeat self-harm is lower in Asia than in the West. The objective of this study was to investigate the prevalence of previous self-harm among a consecutive series of self-harm patients presenting to hospitals in rural Sri Lanka.Method Six hundred and ninety-eight self-poisoning patients presenting to medical wards at two hospitals in Sri Lanka were interviewed about their previous episodes of self-harm.Results Sixty-one (8.7%, 95% CI 6.7-11%) patients reported at least one previous episode of self-harm [37 (10.7%) male, 24 (6.8%) female]; only 19 (2.7%, 95% CI 1.6-4.2%) patients had made more than one previous attempt.Conclusion The low prevalence of previous self-harm is consistent with previous Asian research and is considerably lower than that seen in the West. Explanations for these low levels of repeat self-harm require investigation. Our data indicate that a focus on the aftercare of those who attempt suicide in Sri Lanka may have a smaller impact on suicide incidence than may be possible in the West.