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.
Considerations around environmental pollution and green energy usage have led to environmentally-friendly machines being used in many industrial applications. Permanent magnet (PM) machines are the best solution to substitute the pollutant diesel-powered machines. In such machines, rotor position detection is crucial for safe startup operating. Meanwhile, encoderless controllers have become more reliable, over the years, in supporting the operation of PM machines. The key point, presented by this paper, is to introduce an improved positioning model to detect the rotor-position of interior permanent magnet synchronous machine at halt condition. To verify this objective, only two short duration pulses were injected into the stator windings. Then, the corresponding terminal voltage and current responses were measured and employed to create two memory address lines. Thereby, the memory cells, which contain the rotor position information, could be accessed. This detection model makes a significant improvement in rotor positioning detection of high resolution (1 degree) which represents lower value than most verified results in literature. The model was simulated and tested in a MATLAB/Simulink environment and shows an approximate accuracy 95%. Additionally, the statistical analysis was also employed to support the work outcomes.
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