Three-mode frequency conversion soft switching control method of four-tube Buck-Boost converter

Abstract

The invention discloses a three-mode frequency conversion soft switching control method of a four-tube Buck-Boost converter and belongs to the field of direct current-direct current converters of electric energy conversion devices. The method is characterized in that a minimum value of the inductive current is controlled to be unchanged by changing the switching frequency so that the converter realizes soft switching in a full-load range. A double-closed-loop control strategy combining a voltage outer loop and a current inner loop is adopted for PWM modulation, PWM of a main power tube of theconverter is adjusted within a wide input voltage range, a purpose of adjusting a duty ratio of a Buck unit and a Boost unit is achieved, and therefore output voltage is controlled. A three-mode control method is adopted, and a working mode of a main circuit is selected by sampling and comparing input and output voltages. The method is advantaged in that wide-voltage-range input adaptive to the converter is realized, and soft switching is realized in a full-load range by combining minimum inductive current control and frequency conversion control, so switching loss of the converter is greatlyreduced.

Description

technical field [0001] The invention relates to a three-mode frequency conversion soft switch control method of a four-tube Buck-Boost converter, which belongs to the field of DC-DC converters of electric energy conversion devices. Background technique [0002] As an advanced space propulsion technology, electric propulsion has broad application prospects in the fields of orbit transfer and deep space exploration due to its advantages of high specific impulse and long life. The Power Processing Unit (PPU) is an important part of the electric propulsion system. Its output voltage and output power determine the main performance of the thruster. High efficiency, high power density and high voltage and high power output will become the development direction of the future PPU. . In order to meet the demand of wide input voltage range of PPU in electric propulsion system, it is of great significance to study the buck-boost converter with wide input range. [0003] Compared with ...

AI Technical Summary

Problems solved by technology

In addition, the four-tube Buck-Boost converter has multiple degrees of freedom for the Buck unit corresponding to the duty cycle and switching frequency, the Boost unit for the duty cycle and switching frequency, and the phase shift angle between the turn-on times of the two switching tubes, etc., for optimal control Offers possibilities and challenges

In order to further reduce the volume of passive components and increase the power density of the converter, it is necessary to increase its switching frequency. However, high-frequency hard switching not only has large switching losses, but also generates electromagnetic interference, which affects the normal operation of the converter. Therefore, it is necessary to implement soft switching.

Images