POWER QUALITY IMPROVEMENT IN PFC BRIDGELESS-LUO CONVERTER FED BLDC MOTOR DRIVE

Abstract : This paper presents a PFC (Power Factor Correction) based BL-Luo (Bridgeless-Luo) converter fed BLDC (Brush less DC) motor drive. A single voltage sensor is used for the speed control of BLDC motor and PFC at AC mains. The voltage follower control is used for a BL-Luo converter operating in DICM (Discontinuous Inductor Current Mode). The speed of the BLDC motor is controlled by an approach of variable DC link voltage, which allows a low frequency switching of VSI (Voltage Source Inverter) for electronic commutation of BLDC motor; thus offers reduced switching losses. The proposed BLDC motor drive is designed to operate over a wide range of speed control with improved power quality at AC mains. The power quality indices thus obtained are under the recommended limits of IEC 61000-3-2. The performance of the proposed drive is validated with test results obtained on a developed prototype of the drive.
 EXISTING SYSTEM :
 PMSM works in the torque loop state in the normal running of the vehicle in the process. And the output torque follows VCU given torque demand. The AMT gear may produce teeth crash during shifting process if the PMSM works in the torque control mode. At the same time, it is very difficult to ensure the fast shifting and prolongs the shift time, which would result in large shift impact or shift failure. The motor speed loop control must be realize during the shifting process. DC supply connected to dc-dc converter which can be convention dc converter .it is voltage conversion ratio low.
 DISADVANTAGE :
 • High value of DC link capacitor • No higher gain possible in the conventional converter. • Ripple current might be higher compare to proposed. • Increases the design complexity, cost, and weight. • It have hard switching operation. • very low power factor
 PROPOSED SYSTEM :
 A conventional BLDC motor drive using a front end DBR (Diode Bridge Rectifier) and a high value of DC link capacitor draws highly distorted peaky current which is rich in harmonics. This leads to a very low power factor of the order of 0.7-0.8 and high THD (Total Harmonic Distortion) of supply current at AC mains. A high switching loss on account of high switching frequency occurs which drastically reduces the efficiency. Moreover, it requires high number of sensors and complex control for its operation. A concept of variable DC link voltage for speed control of BLDC motor.
 ADVANTAGE :
 • Sparking, wear and tear of brushes, EMI and noise interference are eliminated • The front end DBR is eliminated in these configurations which reduce the conduction losses • A wide voltage conversion ratio

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