Novel High Efficiency High Voltage Gain Topologies for AC-DC Conversion with Power Factor Correction for Elevator Systems

ABSTRACT:

This paper proposed Novel power factor corrected ac dc rectifier typologies suitable for induction motor drive based elevator application. These converters make use of coupled induct or for power conversion and are capable of providing high voltage gain at low duty cycle and high efficiency. Feedback control loop controls the current flowing through the coupled induct or to achieve unity power factor. The TH D value of the current i approximately 4.8 % which is within the limits prescribed by various standards.

With

the use of coupled induct or, the voltage stress of the switches operating at high frequency is reduced, which reduces switching losses. The loss comparison with the conventional converters shows a reduction of at least 22 % of losses. The proposed scheme also results in reduction of the variable frequency drive’s dc link capacitance value.  As an ultra capacitor bank is interfaced with the dc link through a bidirectional converter for improving efficiency and providing transient power requirements. This also helps in increasing the reliability and dynamic response of the system. The settling time for a step change in voltage reference is reduced by nearly 50%. MAT LAB/Sim u link simulations validates the proposed typologies and schemes.

BLOCK DIAGRAM:

 Fig. 1 Block diagram of an elevator system

 EXPECTED SIMULATION RESULTS:

 Fig. 2(a) Input current and voltage of the proposed 1 p h rectifier system with PFC; (b)3 p h current for PFC operation of proposed rectifier configuration; (c) The dc link voltage step changes for 10μF and 500μF dc link capacitor; and (d) Ultra capacitor current.

CONCLUSION:

Simulation studies proposed, analyzed and validated the Novel AC DC PW M rectifier typologies for 1 p h and 3 p h systems, based on high voltage gain dc dc converter principle. A major advantage of these typologies is that it is possible to achieve higher voltage gain at lower duty ratio. This paper maintained operation symmetry  and achieved the Input power factor correction. The use of coupled induct or s enhances gain, but it also increases the ripple in the input current as there is an increase in turns ratio. Thus, there is a trade off between the achievable gain and the ripple.

comparison

The losses of the proposed converter are compared with the conventional ac dc converter, and observed the reduction of about 22% losses. The losses estimated through experimental studies also reduced from 29 W to 24 W with the use  of proposed topology . This shows a reduction of 17% losses in experiments. Therefore, the proposed converter gives higher efficiency than the conventional ac-dc converters. And the use of an auxiliary storage reduced the dc link capacitance value from 500 μF to 10 μF for a 1 p h system. For the 3 p h system, the auxiliary unit is used as a support during the grid voltage sag condition thereby reducing the dc link capacitance requirement. A low value of dc link capacitance not only helps in reducing the size. And improving the reliability of system, also in improving the dynamic response of the system.

results

The paper presented the simulation results of the complete system . A detailed description of the thought process behind the development of the proposed converter is also presented. The same thought process is extended to the development of such converter typologies. The voltage stress on switch S 2 and S 3 reduces to 1 and 8th of its value as compared to the conventional topology. But, the value of peak current increases ‘n’ times. The increase in peak current increases the high frequency current ripple in the input side. However, the increase in the value of ‘n’ decreases the duty cycle. Therefore, increased the overall efficiency of the converter.

This

paper proposed the unidirectional ac dc typologies. But, they can be made bidirectional by connecting a controllable switch across the diodes. This scheme is useful for the scenarios where the loads are regenerating. These bidirectional typologies are used as dc ac converters to feed power into the grid. Thus, giving very wide and relevant scope of the proposed schemes.

 

REFERENCES:

[1] Ash o k B. K u l k a r n i, H e in Nguyen, E. W. Ga u d e t, “A Comparative Evaluation of Line Regenerative and Non- regenerative Vector Controlled Drives for AC Gear less Elevators” 35th I AS Annual Meeting and World Conference on Industrial Applications of Electrical Energy, Rome, Italy: Institute of Electrical and Electronics Engineers Inc., Pis cat away, NJ, Oct 2000, vol. 3.pp 1431 to 1437.

[2] “IEEE Std. 519”, IEEE Recommended Practices and Requirements for Harmonic Control in Electric Power Systems, 1992.

[3] “IE C 1000 3 2 Int. Std.”, Limits for Harmonics Current Emissions (Equipment Input Cur rent 16 A per Phase), 1995.

[4] “IE C 61000 3 4”, Limitations of Emission of Harmonic Current in Low- Voltage Power Supply Systems for Equipment with Rated Current Greater than 16 A, 1998.

[5] J. Hahn, P. N. En jet i and I. J. Pit e l, “A new three-phase power-factor correction (PFC) scheme using two single-phase PFC modules,” in IEEE Transactions on Industry Applications, vol. 38, no. 1, pp. 123-130, Jan/Feb 2002.

References

[6]Hen g ch u n Mao, C. Y. Lee, D. B o r o ye vi ch and S. Hit i, “Review of high performance three-phase power-factor correction circuits,” in IEEE
Transactions on Industrial Electronics, vol. 44, no. 4, pp. 437-446, Aug 1997.
[7] Y u n g ta e k Jan g and M. M. Jo v a n o v i c, “A comparative study of singles witch three-phase high-power-factor rectifiers,” IEEE Transactions on Industry Applications, vol. 34, no. 6, pp. 1327-1334, Nov/Dec 1998.
[8] M. M. Cameron, “Trends in power factor correction with harmonic filtering,” in IEEE Transactions on Industry Applications, vol. 29, no. 1, pp. 60-65, Jan/Feb 1993.
[9] C. L. Cooper, R. O. Pr  a g ale and T. J. Di o n i s e, “A Systematic Approach for Medium-Voltage Power Factor Correction Design,” IEEE Transactions on Industry Applications, vol. 49, no. 3, pp. 1043-1055, May-June 2013.

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