Analysis and design of stator terminals reversal connection detector for Synchro-to-Digital converter
In this paper, a stator terminals reversal connection detector is presented for Synchro-to-Digital Converter (SDC). This is useful for identifying inadvertent reversal connection of synchro output signals to SDC. Synchro is a positional sensor excited by a sinusoidal signal and gives three electrical signals. The zero crossing outputs of synchro and a clock based on synchro excitation signal are generated. Then the phase relationship between excitation and synchro output signals is analyzed for possible stator terminal reversal connections between synchro and SDC. This method uses simple electronic components such as operational amplifiers, monoshots and flip flops. The analysis, implementation and experimental results are presented.
Modelling and simulation of synchro and synchro-to-digital converter for electrical motor drives
In this study, modelling and simulation of synchro and synchro-to-digital converter (SDC) are presented. This study is useful to estimate the shaft position and speed of induction motor using SDC through a synchro. The SDC uses scott-T circuit to convert three signals of synchro into two signals format. The position information of synchro shaft is present in peak amplitudes of scott-T outputs. A demodulator circuit is designed to extract the peak amplitude levels. The quadrant in which the shaft angle falls is determined by quadrant detector. On the basis of the peak amplitude levels and quadrant information, the synchro shaft angle is computed. This method provides shaft position and speed in digital form. The reuse of quadrant detector in the evaluation of shaft speed shows the effectiveness of the proposed scheme.
Novel polymeric hydrogel composites: Synthesis, physicochemical, mechanical and biocompatible properties
In this research study, novel hydrogel composite films were constructed using different ratios of poly (vinyl alcohol) (PVA)/kappa-carrageenan (KC) (PVA90/KC10%, PVA80/KC20%, PVA70/KC30%, PVA60/KC40%) crosslinked with glutaraldehyde (0.025%) and investigated their physicochemical characteristics such as mechanical, thermal, morphological, swelling behaviour, and cell viability. SEM and FTIR revealed that surface morphology changed to heterogeneous and the presence of molecular interaction among the polymers. PVA90KC10 and PVA60KC40 exhibited smaller and larger pores on surface respectively. The change in the proportion of PVA and KC also triggered the tensile strength (Ts) of the film and the highest Ts observed were 21.60 MPa for PVA60KC40. Moreover, the thermal analysis showed three-phase degradation, and an increase in KC40 concentration results inversely proportional to a decrease in the rate of thermal degradation. Further, swelling and in-vitro biodegradation study confirmed the enhanced perseverance of water uptake for PVA60KC40 (286%) due to pores structure of the hydrogel film and PVA and KC alone degraded faster as compare to other films results suggested higher concentration of PVA90KC10 showed lower degradation rate and highest for PVA60KC40 about 6% and 22% respectively. Further, the cell viability was studied with MTT assay method by using NIH3T3 and HEK-293 cells for biocompatibility study revealed NIH3T3 cells were more biocompatible than HEK-293 and cell viability percent for PVA60KC40 showed the highest cell attachment about 99%. Overall corroborating data obtained from the study attested to the average swelling, appreciable mechanical characters, good interaction between molecules, and cell viability of the constructed PVA/KC hydrogel film, these all characters pave to be used as a potential template for biomedical applications such as tissue engineering and drug delivery.