This study presents a new modulation method for multidirectional matrix converter (MDMC), based on the direct duty ratio pulse width modulation (DDPWM). In this study, a new structure of MDMC has been proposed to control the power flow direction through the stand-alone battery based system and hybrid vehicle. The modulation method acts based on the average voltage over one switching period concept. Therefore, in order to determine the duty ratio for each switch, the instantaneous input voltages are captured and compared with triangular waveform continuously. By selecting the proper switching pattern and changing the slope of the carriers, the sinusoidal input current can be synthesized with high power factor and desired output voltage. The proposed system increases the discharging time of the battery by injecting the power to the system from the generator and battery at the same time. Thus, it makes the battery life longer and saves more energy. This paper also derived necessary equation for proposed modulation method as well as detail of analysis and modulation algorithm. The theoretical and modulation concepts presented have been verified in MATLAB simulation.
Interior permanent magnet motor (IPMSM) was used as air conditioner compressor to reduce the power consumption and improve the performance of the system. Two control methods including maximum torque per ampere (MTPA) and flux-weakening methods were employed to increase the speed range of the air conditioner compressor. The present study adapted the flux weakening algorithm technique which can be used for constant torque and constant power regions. Results indicated that the operation speed range of the IPMSM may increase significantly by using the proposed flux weakening algorithm.
This paper presents a novel electrical power supply system for an isolated system using a matrix converter (MC). MCs are able to convert AC to AC power directly without DC link capacitors. In this paper the MC is used as the main conversion equipment, because arbitrary output, AC to AC and AC to DC, are obtained to use adequate switching pattern. In this paper one AC output with constant frequency, and two DC output for battery storages system is explained, as an example. Direct duty ratio pulse width modulation (DDPWM) is selected to achieve the desired output. In addition, fictitious reference iterative tuning (FRIT) is employed to design the controller gains. The validity of the proposed method is shown using MATLAB/Simulink simulation.
Early fault detection of the induction machine is necessary in order to guarantee its stable and high performance. To evaluate the motor's health and detect existence of any failure in it, any motor parameter is first measured using condition monitoring techniques. The raw signal acquired is then interpret applying signal processing and data analysis procedures. Wavelet analysis of the motor current has been considered as an effective fault detection method. However, there are different types of the wavelet function that can be used for signal decomposition. This paper intends to investigate the ability of different types of wavelet functions for early broken rotor bar detection. Different harmonic components introduced by this fault such as maximum wavelet coefficient, left and right gradients of the maximum coefficient, were extracted and used as a characteristic signature for fault detection. The results indicate that the reliability of the fault detection depends on the type of wavelet function applied for decomposition of the signal.
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