Multiphase DC/DC converter

Abstract

The invention provides a multiphase DC / DC converter which can restrain a ripple current in an inductor less in comparison with no coupling condition of the inductors even a duty cycle fluctuates largely. A dual-phase DC / DC converter (21) has an inductor pair (L1, L2) as an inductor array, wherein switches of switch elements (SW1, SW2) are switched and controlled so as to apply DC input voltage (Vin) in a phase difference of 180 Degrees. The duty cycle is within a range of 5%-40%, and a coupling coefficient (k) is more than -0.4 and less than -0.1. According to the structure, even the duty cycle fluctuates largely, the ripple current in the inductors (L1, L2) can be restrained less in comparison with no coupling condition of the inductors (L1, L2).

Description

technical field [0001] The present invention relates to a multiphase DC / DC converter configured with an inductor array. Background technique [0002] Conventionally, as this kind of multiphase DC / DC converter, there is, for example, disclosed in Patent Document 1 figure 1 A two-phase DC / DC converter 10 is shown. [0003] This two-phase DC / DC converter 10 switches input voltages Va and Vb by two switching devices and converts them into an output voltage Vc. The ratio of the output voltage Vc to the input voltages Va and Vb, that is, the duty ratio is set to 50%, or 5% to 90%. Output voltage Vc is smoothed by two inductors formed as an inductor array by coils 14A and 14B, and capacitor 17 . Coils 14A, 14B are wound around horizontal bars 16A, 16B of iron core 16 , and horizontal bars 16A, 16B together with vertical pieces 16C, 16D form quadrangular iron core 16 . When the input voltage Va is applied to the coils 14A and 14B by switching the switches having a phase differen...

AI Technical Summary

Problems solved by technology

[0006] However, in the multiphase DC / DC converter disclosed in the above-mentioned conventional patent document 1, when the duty ratio is 50%, as described above, the coupling coefficient k between the inductors becomes smaller in the negative direction. The smaller the current, when the duty ratio is 25%, as shown by the dotted characteristic line 20 in the figure, if the coupling coefficient k is too small in the negative direction, the ripple current will increase

In other words, in the above-mentioned conventional multiphase DC / DC converter, if the duty ratio deviates greatly from 50%, there is a problem that the ripple current becomes large at a coupling coefficient k of -0.75 or less.

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