Electric vehicle and its dc-dc converter and control method of dc-dc converter

Abstract

The invention discloses an electric vehicle, a DC-DC converter thereof and a control method of the DC-DC converter, wherein the DC-DC converter comprises an H bridge, and the H bridge comprises a first switch tube, a second switch tube, a third switch tube and a fourth switch tube. The control method includes the following steps of obtaining total times TA, TB, TC, and TD for controlling the H bridge in the first mode, the second mode, the third mode, and the fourth mode while the DC-DC converter is operating, and obtaining set times Tx, Ty, Ti and Tm of the H bridge controlled in the first mode, the second mode, the third mode, and the fourth mode in each working cycle of the operation of the DC-DC converter; and determining the relationship among the total times TA, TB, TC and TD to select the way to control the H bridge when the DC-DC converter is started, and alternately controlling the H bridge according to the set times Tx, Ty and Ti and Tm to perform temperature equalization control on the first switch tube to the fourth switch tube, so that the heating of the first switch tube to the fourth switch tube in the H bridge is relatively balanced, improving the working life of the switch tubes in the H bridge.

Description

technical field [0001] The invention relates to the technical field of electric vehicles, in particular to a control method of a DC-DC converter, a DC-DC converter and an electric vehicle. Background technique [0002] DC-DC converters have always been an important part of the power electronics field. With the development of commercialization of electric vehicles, DC-DC converters have also become one of the important components of electric vehicles. There are many topologies of DC-DC converters. In the field of medium and large power, the full-bridge PWM converter is the most widely used topology. [0003] Among them, there are many control methods for the full-bridge PWM converter, and most of the related technologies adopt the control method of phase-shift modulation and the control method of down-switch modulation. However, when the phase-shift modulation control method is adopted, the super-forearm is easy to realize soft switching, but the lagging arm is not easy to r...

AI Technical Summary

Problems solved by technology

However, when the phase-shift modulation control method is adopted, the super-forearm is easy to realize soft switching, but the lagging arm is not easy to realize soft switching, so the lagging arm is more heated than the super-forearm; when the control method of down-tube modulation is adopted, the upper tube is easy to realize soft switching , and the lower tube is not easy to achieve soft switching, so the lower tube is more heated than the upper tube

[0004] Therefore, both of the above two control methods will cause serious heating problems of the switch tube and affect the working life of the switch tube.

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