J. Soltani and F. Katiraei,
Volume 22, Issue 1 (7-2003)
Abstract
In this paper, using a personal computer (PC), the practical implementation of scalar and vector control methods on a three–phase rotor surface- type permanent magnet synchronous machine drive is discussed. Based on the machine dynamic equations and the above control strategies, two block diagrams are presented first for closed-loop speed controlling of the machine drive/system. Then, the design and implementation of hardware circuits for power, insulating, and signal matching stages are explained along with a description of the written software program for the servo drive system control. These circuits are
used to produce the drive inverter switching pulses. To supply the machine drive, the sinusoidal, uniform sampling and step-trapezoidal PWM voltage source inverters are examined. For closed loop speed control of the drive system, the stator currents and rotor speed signals (in scalar control method only the rotor speed) are sampled on-line. After filtering, buffering and matching operations, these signals are transferred to a personal computer port via a high frequency sampling and high resolution A/D converter. It is worth mensioning that both methods of controlling mathematical calculations is done by computer. Finally, the practical and computer simulation results obtained are demonstrated.
Keywords: Machine Drive, Synchronous Machine, Permanent Magnet, Rotor Surface Type, Scalar and Vector Control, Voltage – Source Inverter, Control by PC.
M. H. Barounian, S. Hesaraki, A. Kazemzadeh,
Volume 37, Issue 1 (6-2018)
Abstract
In this study, a new bioactive and light-cure polymeric calcium phosphate nanocomposite containing a powder phase consisting of pure TetraCalciumPhosphate was synthesized by solid state sintering. By using indomethacin, a non-steroidal anti-inflammatory drug, and a liquid phase including polyhydroxy-based resin, Ethyl Methacrylate was prepared and evaluated after curing with the high-intensity blue light. Phase changes in the cement composition after soaking in phosphate buffered saline (PBS) were investigated using X-ray diffraction (XRD). Morever, changes in the chemical groups in the cement and the microstructure of the cement after soaking in the PBS were investigated by Fourier transform spectroscopy (FTIR) and electronscanning microscopic (SEM) images, respectively. XRD patterns and SEM images showed that after soaking the samples in. the PBS solution, a new calcium phosphate phase with a shape like needle and polka appeared on the surface, which was formed more in the drug-containing sample at a concentration of 5% wt. of these nanostructures. Other results also showed that with the passage of time, the structural degradation in the PBS was due to the conversion of the initial phases to the calcium phosphate phase (apatite). Also, the results of the mechanical strength test of polymeric cement samples containing the drugshowed that the mean compressive strength of the samples after the fixation was about 56 MPa, and it was decreased by 26 MPa with continuous immersion after 21 days.
M. Hosseinzadeh, M. Bozorgmehr, A. Ghasemi, M. Askari,
Volume 37, Issue 2 (9-2018)
Abstract
NdFeB magnetic alloy is one of the hard magnets having the highest maximum energy in the world. The most popular methods of manufacturing magnetic alloys Nd2Fe14B are powder metallurgy and rapid quenching techniques. In this research, the effect of the hot press temperature on the magnetic properties of the hard magnet Nd2Fe14B was studied. Structural studies were carried out using X-ray diffraction, X-ray fluorescence spectrometer and Scanning Electron Microscope; Spectroscopic energy distribution of Nd2Fe14B bulk magnet and the magnetic tests were done using a vibrating magnetometer to investigate the structures and the magnetic properties of the produced samples. The results showed that in addition to the Nd2Fe14B phase, the α-Fe and Nd-rich phase also existed in the structure of the provided magnet. These secondary phases had effectively created exchange couplings with the main phase, improving the magnetic properties. The magnetic properties of the sintered magnets were improved by increasing the press temperature; finally, Nd2Fe14B magnet was made with the maximum energy, which was d higher than 290 kj/m3 .
