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Abstract

Permanent Magnet Brushless DC Motor (PMBLDC) is one of the best electrical drives that has increasing popularity, due to their high efficiency, reliability, good dynamic response and very low maintenance. Its predominant applications are in automotive, aerospace, household appliances, office automation and other industries. This paper proposes a new multistage interleaved buck converter fed PMBLDC drive system having very low switching losses and improved step down conversion ratio, which is suitable for the applications where the input voltage is high and the output voltage is low, where the operating duty cycle is below 50%. When compared with the conventional interleaved buck converter where two active switches are connected in series and a coupling capacitor is connected in the power path, where as in the proposed Multistage Interleaved Buck Converter(MIBC) fed system it can be seen that the voltage stress across all active switches is half of the input voltage before turn on or turn-off when the operating duty cycle is below 50%, the capacitive discharging and switching losses can be reduced considerably, following that the MOSFET fed inverter bridge is feeding the PMBLDC drive system. This allows the proposed multistage IBC to have higher efficiency and operate with higher switching frequency. In addition, the proposed Multistage IBC has a higher step-down conversion ratio and a smaller output current ripple compared with a conventional IBC. The multistage IBC fed PMBLDC drive system features, operation principles, relevant analysis and results are presented in this paper. The validity of this study is confirmed by the experimental results of prototype system with 40-60V Input, 12V/5A output. Further the closed loop system is controlled using Fuzzy controller to enhance the motor performance in various load conditions and the corresponding results are also presented.