Brain and Spinal Cord Rajaram, Veena; Rajaram, Veena
Color Atlas of Fetal and Neonatal Histology
Book Chapter
The brain and spinal cord can be easily identified from the embryonic period of life. They grow rapidly during early fetal life with different parts of the brain growing at different rates throughout ...gestation and early postnatal life. This chapter gives a brief summary of embryology and macroscopic changes in the central nervous system (CNS) with microscopic descriptions and examples of the normal histology of different parts of the brain and spinal cord at various gestational ages.
Switched reluctance motors (SRMs) are rugged, simple in construction and economical compared with synchronous motor and induction motor. They are known to have high-peak torque-to-inertia ratio and ...the rotor mechanical structure is well suited for high-speed applications. Direct torque control (DTC) is known to produce quick and robust response in AC drives. However, during steady state notable torque, flux and current pulsations occur. They are reflected in speed estimation, speed response and also in increased acoustic noise. This paper presents a novel DTC scheme where fast torque response with low ripples in the stator flux and torque of five-phase SRM drive can be achieved. In comparison with DTC of three-phase, the five-phase DTC system has more space vectors providing greater flexibility in selecting the inverter switching states, thus accomplishing a more precise control of the stator flux and torque. Simulation results clearly demonstrate that the combination of DTC with multi-phase SRM realizes higher performance with greater prospects in industries. PUBLICATION ABSTRACT
Switched reluctance motors (SRMs) are rugged, simple in construction and economical compared with synchronous motor and induction motor. They are known to have high-peak torque-to-inertia ratio and ...the rotor mechanical structure is well suited for high-speed applications. Direct torque control (DTC) is known to produce quick and robust response in AC drives. However, during steady state notable torque, flux and current pulsations occur. They are reflected in speed estimation, speed response and also in increased acoustic noise. This paper presents a novel DTC scheme where fast torque response with low ripples in the stator flux and torque of five-phase SRM drive can be achieved. In comparison with DTC of three-phase, the five-phase DT C system has more space vectors providing greater flexibility in selecting the inverter switching states, thus accomplishing a more precise control of the stator flux and torque. Simulation results clearly demonstrate that the combination of DT C with multi-phase SRM realizes higher performance with greater prospects in industries.
In this paper, a novel methodology for control of torque and flux of switched reluctance motor (SRM) drive in a hystersis manner is described. The philosophy of control is the direct torque control ...(DTC) by analysis the non-uniform torque characteristics of the motor. The scheme directly controls the torque and the torque ripple by controlling the magnitude of flux linkage and change in speed of stator flux vectors. Further importance is given to overcome the difficulties of conventional linear and non-linear controls of SRM drives. This new technique can be implemented in real time with low cost microcontrollers and higher simplicity.
In this paper, a novel methodology for control of torque and flux of switched reluctance motor (SRM) drive in a hystersis manner is described. The philosophy of control is the Direct Torque Control ...(DTC) by analysis the non-uniform torque characteristics of the motor. The scheme directly controls the torque and the torque ripple by controlling the magnitude of flux linkage and change in speed of stator flux vectors. Further importance is given to overcome the difficulties of conventional linear and non-linear controls of SRM drives. This new technique can be implemented in real time with low cost microcontrollers and higher simplicity.
Switched reluctance motor, which is robust with high torque ratio and excellent performance, is becoming a competitive replacement for induction motor drives. Tlhe simiplified converter topology with ...unipolar currents of SRM eliminates the problems of shoot through faults and makes the control circuitry simple. A new converter topology is proposed in this paper. A sensor less circuit with SEPIC working as Power Factor Preregulator (PFP) is used to improve the power factor. The advantage of better current regulation and high power factor with simplified gate circuit is achieved at low cost. The proposed converter is suitable for DC and AC low power and high power applications.
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