A New Negative Output Buck-Boost Converter with Wide Conversion Ratio
Abstract
In this paper, a new negative output (N/O) buck-boost converter, which can be applied for applications that need wide range of inverse voltage, is proposed. The steady state, small signal model and power losses of the proposed converter operating in continuous conduction mode (CCM) are analyzed. Comparisons a the traditional buck-boost converter, N/O hybrid buck-boost converter and N/O self-lift Luo converter are presented, and it is found that the proposed converter possesses a widest voltage conversion ratio in these four converters. Finally, a prototype is built, and the simulated waveforms from the PSIM software and the experimental results are presented for validation.
PROPOSED SYSTEM:
In the past few decades, many N/O converters have been proposed. For example, the N/O KY buck converter with the voltage conversion ratio –D who had the fast load transient response was proposed. The N/O KY buck-boost converter with the voltage conversion ratio –2D who possessed no bilinear characteristics was proposed in The N/O KY boost converter which was constructed by integrating a positive to negative path to boost converter with the voltage conversion ratio –1/(1–D) was proposed. For wider conversion ratio, the voltage lift technique is applied to buck-boost or Cuk converter, such as the N/O self-lift Luo converter the enhanced N/O self-lift Cuk converter, the N/O super-lift converter and the voltage-lift-type Cuk converters. However, all the above N/O converters have an unreasonable defect, that is, there is abruptly changing on the voltage across the energy-transferring capacitor which results in a very high current spike flowing through it. This capacitor’s current spike which is only limited by the parasitic parameters cause inherent power loss and EMI.
EXISTING SYSTEM:
several N/O single-switch quadratic PWM converters were proposed. Although they have different structures, they share the same voltage conversion ratio –D 2 /(1–D). They can be regarded as modified cascading connection of buck and buck-boost converters, and require only one switch and three diodes. They have high step-down ability and wider conversion ratio than the traditional buck-boost converter. Switched networks are inserted in the Cuk converter to construct the N/O hybrid Cuk converters. Switched networks are inserted in the buck-boost converter to get hybrid buck-boost converters. One N/O hybrid buck-boost converter with voltage conversion ratio being –D/((1-D)(2-D)) uses a switched-capacitor (SC) structure while another N/O hybrid buck-boost converter whose voltage conversion ratio is –2D/(1-D) uses a switched-inductor (SL) structure. Nevertheless, the added switched networks lead to more diodes, capacitors or inductors to achieve wider conversion ratio, and it results in complex circuit, heavy volume and more power losses. A single-stage switched-capacitor-inductor N/O boost converter with the voltage conversion ratio –1/(1-D) was proposed. However, an additional resonant inductor should be used to limit the current spike caused by the energy transfer capacitor.
CONCLUSION
A new negative output buck-boost converter is proposed, analyzed and validated in this paper. The detailed steady state theoretical analysis and comparisons with other N/O converters are introduced. Small signal model is established and verified by the simulations for further dynamical behaviors analysis and system design. The power losses are analyzed for calculating the efficiency. The results from the theoretical calculations, the simulations and experiments are in agreement with each other, and show that the proposed converter has no current spike and can achieve a wider range of negative output voltage. Thus, the proposed converter can provide a considerable alternative for industrial applications which need wide range of negative output voltage.
REFERENCES
[1] F.L. Luo, “Negative output Luo converters: voltage lift technique,” IEE Pioc. Electr. Power Appl., vo1. 146, no. 2, pp. 208-224, Mar. 1999.
[2] M. Zhu and F. L. Luo, “Enhanced self-lift Cuk converter for negative-to-positive voltage conversion,” IEEE Trans. on Power Electron., vol. 25, no. 9, pp. 2227-2233, Sep. 2010.
[3] K. I. Hwu, Y. T. Yau and J. J. Shieh, “Negative-Output Resonant Voltage Divider” in Proc.IEEE Power Electronics and Driver Systems Conf., Dec. 2011, pp. 935– 939.
[4] A. Cocor, A. Baescu, and A. Florescu, “Elementary and self-lift negative output Luo dc-dc converters used in hybrid cars,” U.P.B. Sci. Bull., Series C, Vol. 77, Iss. 4, pp. 179-190, 2015. [5] B. Axelrod, Y. Berkovich, and A. Ioinovici, “Switched-Capacitor/ Switched-Inductor structures for getting transformerless hybrid dc-dc PWM converters,” IEEE Trans. Circuits Syst. I, Fundam. Theory Appl., vol. 55, no. 2, pp. 687–696, Mar. 2008.
[6] O. Abutbul, A. Gherlitz, Y. Berkovich, and A. Ioinovici, “Step-up switching-mode converter with high voltage gain using a switched capacitor circuit,” IEEE Trans. Circuits Syst. I, Fundam. Theory Appl., vol. 50, no. 8, pp. 1098–1102, Aug. 2003.
[7] Y. Tang, T. Wang, and Y. He, “A switched-capacitor-based active-network converter with high voltage gain,” IEEE Trans. Power Electron., vol. 29, no. 6, pp. 2959–2968, Jun. 2014
[8] K. I. Hwu and Y. T. Yau, “Soft switching of negative-output KY buck converter,” in Proc. IEEE Applied Power Electronics Conference and Exposition, Feb. 2009, pp. 1053-1060. [9] K. I. Hwu, Y. T. Yau and Z. F. Lin, “Negative-output KY buck-boost converter,” in Proc. IEEE Industrial Electronics and Applications Conf., May 2009, pp. 3347– 335