This paper deals with a power factor correction (PFC) based Cuk converter fed brushless DC motor (BLDC) drive as a cost effective solution for low power applications. The speed of the BLDC motor is controlled by varying the DC bus voltage of voltage source inverter (VSI) which uses a low frequency switching of VSI (electronic commutation of BLDC motor) for low switching losses. A diode bridge rectifier (DBR) followed by a Cuk converter working in discontinuous conduction mode (DCM) is used for control of DC link voltage with unity power factor at AC mains. Performance of the PFC Cuk converter is evaluated in four different operating conditions of discontinuous and continuous conduction mode (CCM) and a comparison is made to select a best suited mode of operation. The performance of the proposed system is simulated in MATLAB/Simulink environment and a hardware prototype of proposed drive is developed to validate its performance over a wide range of speed with unity power factor at AC mains.
- Cuk converter
- BLDC Motor
- Power Quality
Fig. 1. A BLDC motor drive fed by a PFC Cuk converter using a current multiplier approach.
Fig. 2. A BLDC motor drive fed by a PFC Cuk converter using a voltage follower approach.
EXPECTED SIMULATION RESULTS:
Fig.3. Simulated performance of BLDC motor drive with Cuk converter operating in CCM
Fig. 4. Simulated performance of BLDC motor drive with Cuk converter operating in DICM (Li).
Fig. 5. Simulated performance of BLDC motor drive with Cuk converter operating in DICM (Lo).
Fig. 6. Simulated performance of BLDC motor drive with Cuk converter operating in DCVM.
A Cuk converter for VSI fed BLDC motor drive has been designed for achieving a unity power factor at AC mains for the development of low cost PFC motor for numerous low power equipments such fans, blowers, water pumps etc. The speed of the BLDC motor drive has been controlled by varying the DC link voltage of VSI; which allows the VSI to operate in fundamental frequency switching mode for reduced switching losses. Four different modes of Cuk converter operating in CCM and DCM have been explored for the development of BLDC motor drive with unity power factor at AC mains. A detailed comparison of all modes of operation has been presented on the basis of feasibility in design and the cost constraint in the development of such drive for low power applications. Finally, a best suited mode of Cuk converter with output inductor current operating in DICM has been selected for experimental verifications. The proposed drive system has shown satisfactory results in all aspects and is a recommended solution for low power BLDC motor drives.
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