Control circuit of cascade type buck-boost converter and control method thereof

Abstract

The invention discloses a control circuit of a cascade buck-boost converter and a control method thereof, which belong to the technical field of power electronic converter control. The structure of the control circuit comprises an output voltage sampling circuit, two error amplifiers, a triangle wave generating circuit, a comparator circuit, a drive circuit and a voltage setting circuit; the controlled buck-boost convertor is formed by the cascade of a booster converter and a buck converter; a first control signal and a second control signal which are generated by comparing the control voltage output by the first error amplifier with triangle wave voltage control the switch tube of the booster converter through the drive circuit; the first control signal sets the control voltage output by the second error amplifier through the setting circuit; and a third control signal and a fourth control signal which are generated by comparing the control voltage output by the second error amplifier with the triangle wave voltage control the switch tube of the buck converter through the drive circuit. The invention has the advantages that the circuits are simple, only one triangle wave generating circuit is required to control two circuits, and the conversion efficiency is high.

Description

technical field [0001] The present invention relates to a buck-boost DC converter, in particular to a control circuit of a buck-boost DC converter, which belongs to the technical field of power electronic converter control, and especially belongs to the non-grid-connected wind energy and solar energy and other green energy power generation systems. The technical field of charging and discharging conversion of energy batteries. Background technique [0002] Buck-boost DC converters are often used for battery charging or discharging conversion, etc. In recent years, they have been widely researched, developed and applied in green energy generation and conversion systems such as solar energy and fuel cells. [0003] Traditional single-switch buck-boost converters include Buck-Boost, Cuk, Sepic, Zeta and other topologies. Due to high device stress, low efficiency, or different input-output grounds, their applications are limited in many occasions. Two new buck-boost converters ...

AI Technical Summary

Problems solved by technology

[0004] The control methods of buck-boost converters that have been studied more in the past are mainly aimed at figure 1 The H-bridge buck-boost converter shown, such as US Patent No. 6166527, Chinese Patent No. 101212173A, and the control of the buck-boost converter formed by the direct cascade connection of the front-stage boost converter and the rear-stage buck converter There are few researches on the method, and the actual control methods of the two converters are similar. figure 1 Some control methods of the buck-boost converter shown can be directly applied to the cascaded buck-boost converter, such as the control methods disclosed in US Patent No. 6166527 and Chinese Patent No. 101212173A. These control methods basically adopt two Two triangular carriers are superimposed and a voltage error amplifier is used, but the control parameters of a voltage error amplifier may not be applicable to the two-stage circuit of the cascaded buck-boost converter at the same time, which will cause the converter to be unstable.

The paper "Rae-Young Kim, Jih-Sheng Lai, A Seamless Mode Transfer Maximum Power Point Tracking Controller For Thermoelectric Generator Applications, IEEE Transactions on Power Electronics, 2008, vol.23, page(s): 2310-2318" studied the stage The digital control method of the cascaded buck-boost converter applied to the occasion of thermoelectric battery, the digital control method focuses on the realization of the maximum power point tracking controller rather than the general control method of the cascaded buck-boost converter, and the digital controller High cost and complex control

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