Bearing current in inverter-fed induction motors can result in premature bearing failure. This paper gives a detailed analysis of common mode voltage as the main source of bearing currents. Moreover, it presents an algorithm to reduce the common mode voltage in multilev More
Bearing current in inverter-fed induction motors can result in premature bearing failure. This paper gives a detailed analysis of common mode voltage as the main source of bearing currents. Moreover, it presents an algorithm to reduce the common mode voltage in multilevel DTC drive. Based on the given analysis, the common mode voltage is reduced to about 33 percent of the initial value. The simulation results in MATLAB/SIMULINK confirm the capability of the algorithm in common mode voltage reduction without degrading the electromagnetic torque and the speed response. The results of real world experiments using TMS320F2812 DSP processor are also provided.
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In recent years, solar energy has gained a great deal of attention. Hence, the photovoltaic (PV) systems which convert the solar energy into electricity should achieve high efficiency, low manufacturing cost, and high quality of electric power to attract the consumers. More
In recent years, solar energy has gained a great deal of attention. Hence, the photovoltaic (PV) systems which convert the solar energy into electricity should achieve high efficiency, low manufacturing cost, and high quality of electric power to attract the consumers. Although Cascaded H-Bride (CHB) inverter is a suitable choice for injection of PV power into grid, its control issues have not been completely solved. One of the main challenges in CHB inverter is low margin of stability when the H-bridge cells are under imbalance operating conditions. In this paper, a new MPPT algorithm is proposed for a CHB photovoltaic inverter. The proposed approach not only tracks the maximum point of distinct PV arrays under symmetric insolation, but also behaves well under asymmetric insolation conditions. The latter is achieved through shifting the operating point of PV arrays and using the modulation index of H-bridge cells as a degree of freedom. The usefulness and validity of new method is confirmed by simulation and experiments on a 7-level CHB photovoltaic inverter.
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