The zero-speed rotor position estimation in surface mounted permanent magnet synchronous motor SM-PMSM represents a challenge due to the weak magnetic saliency in this type of motors. This paper presents a new method to estimate the initial rotor position of SM-PMSMs more simply and more accurately without any form of position or current sensors. It achieves this goal through an injection of three short width pulses and employing only the measurements of the motor terminal voltage responses, which fluctuate sinusoidally with the rotor position. Thereby, memory addresses, or dimensions of a look-up table, were created from the readings of the measured voltages. The memory was primarily loaded with 360 angles, each represents angle of rotor positions. The simulated MATLAB model and experimental results demonstrate the advantages. Comparing with the previous related publications, this research work has fulfilled two main contributions. The first is in achieving a rotor position estimation of resolution. The second is in eliminating the technique needed for detection of the rotor magnet polarity. The measured rates of error for the MATLAB model and the practical model were 2% and 5% respectively

This paper introduces the design and implementation of a wireless communication system with MATLAB based on orthognal frequency division multiplexing technique (OFDM). The constructed system is consisting of transmitter, fading channel and receiver. At the transmitter, the transmitted signal first modulated with PSK modulation, and then multiplexed with OFDM technique to achieve a higher bit rates transmission. The signal was then transmitted through a frequency selective channel with 6 taps. In the receiver parity. The received faded signal processed to be de-multiplexed and de-modulated. Then, a frequency domain equalizer was adopted to remove the fading noise and the inter-symbol interference from the received signal that introduced due to the fading channel. In order to inspect the performance of the frequency equilizer, bit error rate for the overall system was calculated at the receiving point and to recover the original information signal. The simulation results of the designed system as well as the frequency equilizer showed a robustness against the frequency selective faded channel effects. The maximum obtained bit error rate was around 10-5, which means that original signal was effectively recovered.

Space Vector Pulse Width Modulation, SV-PWM, is an efficient technique for dc to ac voltage conversion through an inverter of power electronics devices. This paper presents a proposed memorized approach for SV-PWM implementation. The work bases on storing six symmetric pattern formats of space vector in a memory structure. Then, sequential fetching of the stored data provides basic optimum firing triggers TRA, TRB and TRC for driving the inverter switching elements. Main contribution of the paper is controlling the inverter output frequency online through adjusting the fetching period. Moreover, the presented approach characterizes by simplicity, cost effective and activity in achieving the space vector technique. Validity of the proposed method was practically examined through a hardware built workbench, which based on the microcontroller ATMEGA 2560. Meanwhile, the optimum firing sequences were exported to a MATLAB algorithm to check the harmonics, which are expected to accompany the inverter output ac power.

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Non-crystalline silicon has a leading position in many fields of electronic industrial applications. With this type of silicon material, localized states in the middle of the energy gap, play an important role in determining the wafer characteristic. Therefore, the region around the middle of the energy gap is regarded as the center of charge carrier activities, whereas the occupancy function is employed to define the condition of the localized states, whether they are empty or filled with charge carriers. The occupancy function is divided into three parts within the energy gap. The most important part is the gap center which is always a flat region of a certain width and level. This paper investigates the effect of various parameters on width and level of the flat region of the silicon wafer occupancy function. The work was achieved with the aid of statistical approaches for curve fitting through regression equations. The main contribution is verified through creating a novel MATLAB-SIMULINK model for this case study. The proposed model may represent a significant addition to the Simulink library that does not have such a modelling block.