Modulation method of three-phase isolation type bidirectional direct-current converter under double PWM (pulse width modulation)

Abstract

The invention discloses a modulation method of a three-phase isolation type bidirectional direct-current converter under double PWM (pulse width modulation). The modulation method includes steps of 1) determining seven switch modes by adopting a PWM strategy according to the conditions that phase shift angle and duty ratio of corresponding drive signals on two sides of a three-phase transformer change to generate different voltage and current waveforms on two sides of the transformer; 2) calculating soft switching ranges corresponding to the switch modes; 3) calculating minimum current peak flowing through the three-phase transformer within the soft switching range of each switch mode; 4) comparing calculation results to obtain the situation that the current peak flowing through the three-phase transformer is minimum on the premise of soft switching within the integral power range; 5) giving output power and voltage transmission ratio and determining the switch modes and corresponding the duty ratio and the phase shift angle by judging the range where the output power and the voltage transmission ratio belong to. On the basis of soft switching, the current peak is minimum, switch loss of switching devices is reduced and efficiency of the converter is improved.

Description

technical field [0001] The invention belongs to the technical field of three-phase isolated bidirectional DC converters, and in particular relates to a modulation method of a three-phase isolated bidirectional DC converter under double PWM. Background technique [0002] Pulse Width Modulation (PWM), the abbreviation of "Pulse Width Modulation" in English, referred to as Pulse Width Modulation, is a very effective technology that uses the digital output of a microprocessor to control analog circuits. It is widely used in measurement, Communication into many areas of power control and conversion. [0003] The existing three-phase isolated bidirectional DC converter consists of a three-phase high-frequency transformer connected to two three-phase bridge circuits, and its topology is as follows: figure 1 shown. It is an isolated, bidirectional, buck-boost DC converter. It has the advantages of high power density, low switching stress and easy realization of soft switching. I...

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Problems solved by technology

[0005] In order to overcome the defects in the above-mentioned prior art, the object of the present invention is to provide a modulation method of a three-phase isolated bidirectional DC converter under dual PWM, on the basis of which the modulation method can realize soft switching in the full power range, Minimizes current peaks to increase efficiency to address issues that lead to reduced efficiency

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