Solid State Phenomena Vols. 147-149

Abstract: Field analysis was applied to the simulation of magnetic field distribution and calculation of its integral parameters in an active magnetic bearing (AMB). 3D Finite Element Method (FEM) was employed for the computations. The magnetic force which act on the moving shift and stiffness parameters of AMB were calculated under the steady state conditions. The measurement results confirm rightness of the field modeling. The inductances of the stator winding coils were computed, as well. They have been used for the analysis of the AMB dynamics, which is not presented here.

Abstract: As one of applications for Microstructured Optical Fiber, a new device for measurement of low gas concentration was designed. In the developed system the Photonic Bandgap Fiber (PBGF) was used as a gas cell. Proposed technique allowed reducing gas sample volume to 0.01 cc. The gas flow inside core of fiber was simulated and result was confirmed experimentally. During the experimental work several types of fibers of various parameters were specially designed, produced and used. Core diameters ranged from 10.9 μm to 700 μm. Various cutting techniques for fibers such as using the fiber cleaver, Focused Ion Beam and Cross Section Polisher were investigated.

Abstract: The design and introductory calculations of a bearingless induction motor is presented in the paper. Advantages of bearingless motors are: the lack of a mechanical contact between the journal and the bush, small additional losses, no need of lubricants, no tear and wear, the shaft is shorter, they have low cost of production due to smaller number of wires on the stator, etc

Abstract: The paper presents the model of vector controlled induction motor. Induction motor model is carried out in reference frame, fixed on stator. Elaborated model of the drive is suitable for investigation dynamics because output signals appear as real currents, flux linkages and other variables. Vector control law model is implemented for variables in synchronous reference frame; therefore controller operates with transformed variables. Structure of designed model reflects the real variable speed drive. Model of vector controlled induction drive comprise model of induction motor, feedback signals and blocks as well as speed and flux reference blocks and controllers for producing motor supply signals. Feedback blocks are used for calculation stator current vector in the rotor flux linkage reference frame. For flux and speed control are designed lag controllers. Between advantages of that model is additional simulation of current channel law.

Abstract: Two issues are discussed in the paper. The first one concerns the FEM modelling of the magnetic field enclosing the permanent magnet – reed switch system. The system works as the motion detection device of the hydraulic servoactuator distributor to improve the helicopter steering reliability and flight safety. The second one describes optimization of the active magnetic bearing (AMB) design with the FEM. The optimization has two goals: weight reduction and bearing load capacity. The bearing is applied to active vibration control of helicopter flexible tail rotor shaft.

Abstract: There is presented PWM power amplifier for the inductance load. The PWM amplifier assigns to supply the active magnetic bearings which support shaft and flexible rotor. The power amplifier has got ten channels. The channels have got pulse bridge inverter with modulation PWM. There is showed construction, principle of operation, simulation and experimental result the PWM power amplifier.

Abstract: he paper presents a three-phase rectifier with sinusoidal source current which enables energy to be fed back to the AC supply network. It has been used in a flywheel energy storage system. The principle of operation and control methods of the three-phase rectifier are discussed. The experimental setup employing a DSP controller co-operating with CPLD device is described. Results of experimental investigation for both the steady and transient states are presented in the concluding section.

Abstract: Electromagnetic tubular linear actuators are very important in mechatronic systems. The new construction of the linear actuator is presented in the paper. Many calculations with magnetic field analysis have been carried out for the new construction of the object. It was a five-phase permanent magnet tubular linear actuator. The static and dynamic parameters of the actuator have been calculated and measured, as well. A good correlation between the results validates the mathematical modeling of the actuator.

Abstract: The paper presents a methodology of designing a velocity control system for a DC motor servo drive that is widely used in CNC power transmission systems. There are presented both: the algorithm for tuning the velocity controller for a specified value of overshoot and a fuzzy-logic based tuning of PID controller procedure. Usage of a method called PID-OVR, which ensures the assumed overshoot in a control loop, allows one to chose initial settings of the controller. This algorithm is used with assump¬tions that the load of motor is equal to zero and that the elec¬trical Tem and mechanical Tmm parameters (time constants) are known accurately. Since all this parameters are always encumbered with errors and the load torque of motor during its work is greater than zero the initially assumed controller settings may not ensure well enough quality of the velocity regulation. Overshoot and damping factor of a step response in a velocity control loop, both of these parameters are used in a fuzzy-logic based tuning of PID controller procedure. This procedure do not require any active identification experiments to be carried out, thanks to which the control performance is not affected.