Dual mode control strategy for BLDC motor drive with Bridgeless Canonical Switching Cell converter

The brushless DC (BLDC) motor can be controlled either by fixed dc link voltage control with Pulse Width Modulation (PWM) or by variable dc link voltage control with Pulse Amplitude Modulation (PAM). But neither of these can be a proper method for BLDC motor. Since the PWM control induces high current and torque ripple at high speeds and PAM control limits its application at low speeds due to the small DC link voltage generation. So a drive method merging both these methods is planned with Power Factor Correction (PFC). The motor driver consists of a Bridgeless Canonical Switching Cell (BL-CSC) PFC converter and a 3-phase PWM inverter. The BL-CSC PFC converter operates on Discontinuous Continuous Mode (DCM) to achieve unity power factor at the ac mains. The speed of the BLDC motor is controlled either on the converter side by varying the input voltage of the PWM inverter or on the motor side by keeping the inverter input constant. And the bridgeless configuration of the Canonical Switching Cell (CSC) converter provides less power losses due to the partial removal of diode bridge rectifier (DBR). The hybrid drive method or the dual mode control has been analyzed using MATLAB Simulink. The PFC operation is verified and both load & supply variations are also illustrated in this paper.