جستجوی مقالات مرتبط با کلیدواژه « اینورترهای چندسطحی » در نشریات گروه « برق »

This paper proposes a new topology for three phase cascaded multilevel converter based on multilevel modules (MLM) and three-phase bridge. The main advantages of the proposed topology, compared to the other topology converter are significantly reduction of the number of power switches and diodes as the number of output voltage levels increases. To achieve the proper levels in the output voltage, an algorithm is introduced to determine the value of DC sources. In the other part of this study, is introduced the determining the minimum values of switches, diode, DC sources, so on to gain the maximum levels at the output voltage. Also, how specifying the switching interval in order to reduce the total harmonic distortion (THD) is proposed that using this switching method, the output voltage THD is minimized. To show the validity of proposed topology, a 125 level three-phase inverter is designed and simulated using PSpice. In addition, to verify the performance of proposed configuration in desired output voltage generation, a sample output voltage containing 3th and 5th harmonic is generated using this topology and the obtained results are evaluated.

In this paper a new topology of three-level inverters with ten-switch is proposed to control low voltage three phase induction motor. Ten-switch inverter is a reduced-switch-count three level inverter which compared to conventional topologies such as NPC, CHB and flying capacitor has lower count of semiconductor switches. Thus, it enjoys from lower cost, lower volume and lower weight. In this paper, a direct torque control (DTC) scheme based on switching table is developed to control a ten switch inverter. Simulation results of controlling induction motor fed by a conventional two-level inverter, NPC and proposed 10 switch inverter are presented and they are compared together in different aspects. Results confirm the effectiveness of the proposed topology and its control method.

In practical applications of inverters, unbalanced conditions may be occurred. For instance, semiconductor switches of a converter may not be exactly the same or switching circuit may be unbalanced. This unbalance leads to additional harmonics in the output of converter. The additional harmonics usually are not considered in the design of circuit, so cause many problems. For precise investigation of these harmonics, a new model of inverter based on switching functions is presented. With this model, analytical equations of harmonics in unbalanced switching are calculated. These analytical equations can be used for designing process such as investigation of optimal cases or elimination of undesired harmonics. The accuracy of the analytical calculations is verified by simulation results. As well, an experimental prototype is constructed to verify analytical results.