ABSTRACT:
Brushless dc
motor still suffers from commutation torque ripple, which mainly depends on
speed and transient line current in the commutation interval. This paper
presents a novel circuit topology and a dc link voltage control strategy to
keep incoming and outgoing phase currents changing at the same rate during
commutation. A dc–dc single-ended primary inductor converter (SEPIC) and a
switch selection circuit are employed in front of the inverter. The desired
commutation voltage is accomplished by the SEPIC converter. The dc link voltage
control strategy is carried out by the switch selection circuit to separate two
procedures, adjusting the SEPIC converter and regulating speed. The cause of
commutation ripple is analyzed, and the way to obtain the desired dc link
voltage is introduced in detail. Finally, simulation and experimental results
show that, compared with the dc–dc converter, the proposed method can obtain
the desired voltage much faster and minimize commutation torque ripple more
efficiently at both high and low speeds.
KEYWORDS:
1. Brushless dc motor (BLDCM)
2. Commutation,
3. Dc link voltage control
4. Single-ended primary inductor converter (SEPIC)
5. Torque ripple
SOFTWARE:
MATLAB/SIMULINK
CIRCUIT DIAGRAM:
Fig.
1. Configuration of BLDCM driving system with a SEPIC converter
EXPECTED SIMULATION RESULTS:
Fig.
2. Simulated phase currents at n = 1000 r/min. (a) Without dc link voltage
control. (b) With dc link voltage control by a SEPIC converter.
Fig.
3. Simulated phase currents at n = 2500 r/min. (a) Without dc link voltage
control. (b) With dc link voltage control by a SEPIC converter.
Fig.
4. Simulated electromagnetic torque at n = 1000 r/min. (a) Without DC
link voltage control. (b)With DC link voltage control by a SEPIC converter.
Fig.
5. Simulated electromagnetic torque at n = 2500 r/min. (a) Without dc
link voltage control. (b) With dc link voltage control by a SEPIC converter.
CONCLUSION:
A new circuit topology and control
strategy has been proposed to suppress commutation torque ripple of BLDCM in
this paper. A SEPIC converter is placed at the input of the inverter, and the
desired dc link voltage can be achieved by appropriate voltage switch control.
The switch control separates the two procedures, adjustment of SEPIC converter,
and regulation of speed so that torque can respond immediately during transient commutation
and robustness can be improved. Furthermore, no exact value of the commutation
interval T is required, and the proposed method can reduce commutation
torque ripple effectively within a wide speed range. Finally, the simulated and
measured results show an improved performance of the proposed method.
REFERENCES:
[1] Y.-C. Son, K.-Y. Jang, and B.-S.
Suh, “Integrated MOSFET inverter module of low-power drive system,” IEEE
Trans. Ind. Appl., vol. 44, no. 3, pp. 878–886, May/Jun. 2008.
[2] A. Sathyan, N. Milivojevic, Y.-J.
Lee, M. Krishnamurthy, and A. Emadi, “An FPGA-based novel digital PWM control
scheme for BLDC motor drives,” IEEE Trans. Ind. Electron., vol. 56, no.
8, pp. 3040–3049, Aug. 2009.
[3] G. J. Su and J. W. Mckeever,
“Low-cost sensorless control of brushless DC motors with improved speed range,”
IEEE Trans. Power Electron., vol. 19, no. 2, pp. 296–302, Mar. 2004.
[4] C.-T. Pan and E. Fang, “A phase-locked-loop-assisted
internal model adjustable-speed controller for BLDC motors,” IEEE Trans.
Ind. Electron., vol. 55, no. 9, pp. 3415–3425, Sep. 2008.
[5] C. Xia, Z. Li, and T. Shi, “A
control strategy for four-switch threephase brushless dc motor using single
current sensor,” IEEE Trans. Ind. Electron., vol. 56, no. 6, pp.
2058–2066, Jun. 2009.
