ABSTRACT:
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.
KEYWORDS:
1.
CCM
2.
Cuk
converter
3.
DCM
4.
PFC
5.
BLDC Motor
6.
Power Quality
SOFTWARE: MATLAB/SIMULINK
BLOCK DIAGRAM:
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.
Fig.
7. Steady state performance of Cuk converter fed BLDC motor drive
at
rated condition with DC link voltage as (a) 200V and (b) 50V.
Fig.
8. Test results of proposed BLDC Motor drive showing (a) Supply voltage with
inductors currents and intermediate capacitor’s voltage and (b) its enlarged
waveforms. (c) Waveform of voltage and current stress on PFC converter switch.
Fig.
9. Test results of proposed BLDC motor drive at rated load on BLDC motor during
(a) Starting at DC link voltage of 50V (b) Step change in DC link voltage from
100V to 150V and (c) Change in supply voltage from 250V to 170V.
Fig.
10. Power quality indices of proposed BLDC motor drive at rated load on BLDC
motor with (a-c) DC link voltage as 200V at rated conditions (d-f) DC link
voltage as 50V at rated conditions (g-i) DC link voltage as 200V and supply
voltage as 90V at rated load (j-l) DC link voltage as 200V and supply voltage
as 270V at rated load.
CONCLUSION:
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.
REFERENCES:
[1] J. F. Gieras and M. Wing, Permanent Magnet Motor
Technology- Design and Application, Marcel Dekker Inc., New York, 2002.
[2] C. L. Xia, Permanent Magnet Brushless DC Motor Drives and
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Driver for the Single-Phase Brushless DC Fan Motor with Hybrid Winding Structure,”
IEEE Trans. Ind. Electron., Early Access, 2012.
[4] S. Nikam, V. Rallabandi and B. Fernandes, “A high torque
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IEEE Trans. Ind. Appl., Early Access, 2012.
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