Cuk Converter Fed BLDC Motor with a Sensorless Control Method

Cuk converter fed brushless dc motor (BLDC) drive as a cost-effective solution for low-power applications is presented. The speed of the BLDC motor is controlled by varying the dc-bus voltage of a voltage source inverter (VSI) which uses a low frequency switching of VSI for low switching losses. A diode bridge rectier followed by a Cuk converter working in a continuous conduction mode (CCM) is used for control of dc-link voltage with unity power factor at ac mains. Performance of the PFC Cuk converter is evaluated under continuous conduction mode of operation. The performance of the proposed system is simulated in a MATLAB/Simulink environment The simulation of sensorless operation of permanent magnet brushless direct current (BLDC) motor in CCM is simulated and is based on detection of zero crossing from the terminal voltages differences. This method relies on a difference of line voltages measured at the terminals of the motor. This difference of line voltages provides an amplified version of an appropriate back EMF at its zero crossings. The commutation signals are obtained without the motor neutral voltage. The effectiveness of this method is demonstrated through simulation and hardware prototype of the drive is developed to validate its performance.