Performance of a vector controlled PMSM drive based on proportional–resonance control under single-phase open circuit fault

In this paper, a vector controlled PMSM drive based on a proportional–resonance controller (PR) under open circuit fault (OCF) is proposed. The PR controller is used to generate the stator voltages. While the field-oriented control (FOC) approach has been implemented using the pulse width modulation (PWM) technology. The simulation is built using MATLAB/ Simulink. Hardware experiments were performed, and the results captured using dSPACE DS1104. The behaviour of the PMSM is studied under three operations: healthy, faulty, and post-fault operation. Moreover, the speed control of the PMSM under the three operations has been presented. The simulation and the experimental results show a fast dynamic response with some ripple in the response of speed and torque during the healthy and post-fault operations. On the other hand, during the OCF, the ripple in the torque and speed response increases. However, the proposed method proves its efficacy by keeping the motor speed nearly at the input reference speed as well as guaranteeing the continued operation of the PMSM with good steady-state and dynamic performance

Three-phase PMSM vector control using decoupled flux and speed controller

Described in this paper is a control method for a permanent magnet synchronous motor (PMSM) based on a decoupled speed and flux control technique where the speed and the flux of the PMSM are controlled separately. The actual torque and the feedback flux of the PMSM are directly calculated from the stator currents, while the speed and the angular position are read from the motor. Therefore, no flux/torque or speed/position estimators are required. A separate flux controller is used to generate the d-axis current error. The speed controller is used to generate the reference torque, while the q-axis current error is generated by the constant torque relation. The performance of the overall control system is examined using the Matlab/Simulink environment. The experimental work is tested using dSPACE DS1104. The performance of the motor is presented with reference speed step change. The simulation and the hardware results prove the effectiveness of the proposed method in controlling the speed and flux of a three-phase PMSM

Shunt active power filter voltage sensorless method using a PR controller for unbalanced grid conditions

Unbalanced issues and power quality problems can be handled using shunt active power filters (APFs). Under weak grid conditions and unbalanced grid impedance, the unbalanced three-phase load leads to unbalanced grid currents and point-of-common-coupling voltages. As a result, there will be a significant fluctuation in the real and reactive power of the grid. Several shunt APF control methods were used to solve unbalanced problems. Both voltages and currents measurements are required in the control method. Proposed in this article is a new voltage sensorless control method of shunt APF by using current measurements only. The reference current of the controller was determined from the positive-sequence component of the measured load currents. The APF was controlled by a PR controller. The proposed approach can eliminate fluctuation in the real and reactive power and balance point-of-common-coupling voltages and grid currents. Simulation and hardware experiments were used to verify the proposed method’s performance

Spatio-temporal analysis of DNA damage repair using the X-ray microbeam

Cellular response to radiation damage is made by a complex network of pathways and feedback loops whose spatiotemporal organization is still unclear despite its decisive role in determining the fate of the damaged cell. The single-cell approach and the high spatial resolution offered by microbeams provide the perfect tool to study and quantify the dynamic processes associated with the induction and repair of DNA damage. The soft X-ray microbeam has been used to follow the development of radiation induced foci in live cells by monitoring their size and intensity as a function of dose and time using yellow fluorescent protein (YFP) tagging techniques. Preliminary data indicate a delayed and linear rising of the intensity signal indicating a slow kinetic for the accumulation of DNA repair protein 53BP1. A slow and limited foci diffusion has also been observed. Further investigations are required to assess whatever such diffusion is consistent with a random walk pattern or if it is the result of a more structured lesion processing phenomenon. In conclusion, our data indicates that the use of microbeams coupled to live cell microscopy represent a sophisticated approach for visualizing and quantifying the dynamics changes of DNA proteins at the damaged sites

Genetic homogeneity and phage susceptibility of ruminal strains of Streptococcus bovis isolated in Australia

The genetic homogeneity of 37 strains of ruminal streptococci was investigated by comparing DNA fragment profiles on agarose gels following restriction endonuclease digestion with Hae III, Cfo I and Msp I. Thirty strains were indistinguishable from Streptococcus bovis strains, 2B, H24 and AR3. The remaining three strains were similar but not identical to a ruminal strain of Strep. intermedius (AR36). In addition, the susceptibility of these strains to infection by five bacteriophages was examined. Three of the phages (φSb02, φSb03 and φSb04) were specific to the strain of Strep. bovis from which they were isolated, while phages 2BV and φSb01 infected one and two strains, respectively, in addition to their primary host. It was concluded that although Strep. bovis is relatively homogeneous genetically, broad host range phages appear to be uncommon with this bacterial species