PMSM Rotor Speed and Position Estimator

Estimation techniques have been developed for flux observer, rotor position, and speed. The techniques have a common problem of the offset in voltage-sensor and current-sensor outputs increasing during integration, causing instability. This paper describes an attempt to overcome the problem through estimations of rotor position and speed of a permanent magnet synchronous motor (PMSM) by three methods: with cascaded low pass filter (LPF), with adaptive sensorless rotor flux observer, and with sliding mode observer (SMO). Simulation on Matlab/Simulink validated the proposed method. The advantages and drawbacks of each implementation are discussed

A snapshot of pre- And Post-intervention changes among cardiovascular disease patients participating in the new Smoking Cessation Program

Background: The study evaluates the changes of pre and post stages of behavioral change, motivation level, and smoking status among cardiovascular disease patients, participating in the new smoking cessation program in Hospital Tengku Ampuan Afzan, Kuantan. Methods: A total of 65 adult cardiac patients were randomly distributed into two groups, i.e., intervention and control group, who were baseline smokers and assessed in three phases. Initially, the first, second, and third phase collected the information about their demographic details, their smoking status, and smoking status using cotinine amylase strip, respectively. Results: It showed that behavioral change was significant for the control group (P value = 0.031), while motivation level improved for both groups (i.e., control, P value = 0.000 and intervention group, P value = 0.001). The smoke quitting status percentage was higher for intervention group 41.9% and lower for control group 20.6%; however, the P value was insignificant for both control group (1.000) and intervention group (0.250). Conclusions: This study suggests a need for more personal testimonial videos to focus on other smoking-related diseases

Switching-table and space vector modulation direct torque control of permanent magnet synchronous motor drives simulation

Direct torque control (DTC) is considered as the best alternative for permanent magnet synchronous (PMSM) drives. Classic switching-table based DTC has high torque and flux ripple due to the implementation of hysteresis control. Switching frequency can be made constant by replacing hysteresis control with space vector PWM (SVM) and requires mathematical modification on SVM input. Propotional+integral control and reference flux vector calculation (RFVC) is used to improve the torque response, flux and torque ripple. These scheme still utilizing similar torque and flux estimator as introduced in classic DTC. Propotional+integral control DTC performed better in term of torque step response whilst RFVC torque and flux ripple are the best among these three schemes

2-DOF Lead-Plus-PI Control Approach For Magnetic Levitation System

This paper proposes Two-Degree of Freedom (2-DOF) Lead-plus-PI a classical linear control system for positioning control of a magnetic levitation (maglev) system. Maglev system has practical importance in many engineering system. However, maglev has inherently nonlinear and open loop unstable characteristics. Thus, it is a challenging task to control the maglev system. In this paper, the 2-DOF Lead-plus-PI controller is developed to control the positioning performance of the maglev system as it has simple control structure and straightforward design procedure that can be designed using root locus technique and Ziegler Nichols second method. The proposed controller can be easily implemented into the maglev system without require deep knowledge in control system. The effectiveness of the proposed controller is validated experimentally. Experimental results show the 2-DOF Lead-plus-PI controller has a better positioning accuracy and transient response in point-to-point motion, as compared to Lead-plus-PI controller. The proposed controller shows a position accuracy of 40 μm, which is around the vibration amplitude of the sensor output in open loop. It also takes less than 1 second to stabilize the ball within ± 200 μm and the steady state error has improved to around 45% in point-to-point positioning performance. Besides, the proposed controller also reduced the tracking error to about 48% as compared to Lead-plus-PI controller

The Fuzzy Logic Approach for Modelling Object Physical Features and Holes Occupancies

Abstract— This paper introduces the fuzzy logic approach for modelling object physical features and holes occupancies. There are four major algorithms involved. They are known as coloured balls detection, holes recognition, cupboard’s holes’ position modelling and pixel coordinate system (PCS) to robot coordinate system (RCS) conversion. The inputs are received from a webcam which is not calibrated. This project introduces how to assist a robot arm system using vision system for making decision during conducting an operation or task. The system discussed in this paper had successfully tested and no camera calibration needed because the system has self calibration effect since the cupboard had modelled by the information of the holes of the cupboard and not by it environment. This system is generated in on-event processes and suitable for indoor environment applications with low time frame rate camera. This project introduces how to assist a robot arm system using vision system for making decision during conducting an operation or task. One of the advantages of this project is that it only used a camera and image processing generated by the algorithms itself without additional sensor such as sonar or IR sensor

High Performance Torque Control of BLDC Motor

This paper presents a simulation study using Matlab introducing Direct Torque Control (DTC) method which is implemented on BLDC motor. BLDC motor is well known and has been widely used in the industrial area due to the high speed and power density. Electronic commutation is by far more favourable compare to the conventional DC motor which uses brushes and commutators that wears and tears by time. However, a precise controller is required in order to control the switches prior to commutation process. DTC of BLDC combines a simple control method and a demanding motor to complete a better drives system. Based on in depth analysis of BLDC mathematical model and the operation of DTC system, a simulation model is developed using Matlab/Simulink. The capability and performance of torque and flux control of the drive system is verified

Improved Performance of Direct Torque Control of Induction Machine with 3-Level Neutral Point Clamped Multilevel Inverter

A 3-Level Neutral Point Clamped (NPC)Multilevel Inverter was implemented to improve the performance of Direct Torque Control (DTC) of Induction Machine. Larger torque ripple and variable switching frequencies are known as the major problems in DTC of induction machine. This paper aims to propose a suitable voltage vector selection to provide better torque regulation and switching frequency which consequently minimize the major problems. A simple switching strategy was proposed using 7-level torque hysteresis and 2-level flux hysteresis controllers to give more options in selecting an appropriate voltage vector, inherently, according the motor operating conditions. The improvements offered were verified through simulations

Thickened carotid intima media thickness and carotid atherosclerosis among lupus nephritis patients : the role of traditional and lupus-specific factors.

AIM: The objectives of this study were to investigate the frequency of thickened carotid intima media thickness (CIMT) and atherosclerosis among lupus nephritis (LN) patients and to study their associated risk factors. METHOD: In this cross-sectional study, carotid ultrasonography was performed on consecutive LN patients to determine CIMT and presence of carotid plaques. CIMT was considered to be abnormally thickened if it was more than the 75th percentile matched for age and sex from the 'Carotid Atherosclerosis Progression Study'. The association between thickened CIMT with traditional cardiovascular risk factors and lupus characteristics were examined. A total of 83 patients with the mean age of 33.6 ± 10 years were recruited. RESULTS: Fourteen patients (16.9%) had thickened CIMT and three (3.6%) had carotid plaques. On univariate analysis, traditional risk factors significantly associated with thickened CIMT (P < 0.05) were patient's current age, diabetes mellitus and waist circumference. Meanwhile, a lower serum C4 levels and higher serum C-reactive protein levels were the lupus-specific factors associated with thickened CIMT (P < 0.05, P < 0.05 and P < 0.01, respectively). In logistic regression analysis, the independent predictors of thickened CIMT were age of diagnosis, lower serum C4 levels and waist circumference (P < 0.05). CONCLUSION: More lupus specific factors were independently associated with thickened CIMT, suggesting that a multi-targeted approach of treatment addressing both the lupus and traditional cardiovascular risks are very important. Larger prospective studies of these special risk factors are indicated

Optimal Torque Control Performance of DTC of 5-Phase Induction Machine

In this paper, optimal voltage vector selection for high-performance of Direct Torque Control (DTC) of five-phase induction machine is presented. The de-coupled control of stator flux and electromagnetic torque based on hysteresis controllers as employed in conventional DTC is applied to retain the simplicity and to provide quick instantaneous control. A single complete look-up table that selects the most optimal voltage vectors according to the motor operating condition is proposed. This improves DTC performances such as excellent torque dynamic control, minimization of torque ripple, high-efficiency (due to lower switching frequency) and extension of constant torque region. All the improvements are validated through simulation results