Direct-current (DC) - DC converter, power converter and control method thereof

Abstract

The invention provides a direct current (DC) - DC converter, a power converter and a control method thereof. The DC - DC converter comprises an output circuit, a rectangular wave generator, a resonance groove, a detection unit and a control unit. The rectangular wave generator comprises a bridge arm which comprises a first switch and a second switch, the first switch and the second switch are connected in an electric coupling mode. The detection unit is used for detecting states of a load, when the load is in a light load state or a zero load state, the control unit controls on and off of the first switch and the second switch through a waviness width modulation mode to convert an input voltage to at least one rectangular wave to be provided for the resonance groove, the duty ratio of the second switch is complementary with that of the first switch, and therefore the gain of the DC - DC converter is enabled to be larger than one. The switch batch-type waviness width modulation control mode works in the light load state and the zero load state, and therefore the total on-off times of the converter in unit time can be effectively reduced, light load efficiency can be effectively improved, and the requirement that loss in the light load state is limited is met.

Description

technical field [0001] The invention relates to power electronics technology, in particular to a DC-DC converter, a power converter and a control method thereof. Background technique [0002] In recent years, due to the widespread implementation of the energy saving movement around the world, more and more customers require switch mode converters to achieve high conversion efficiency in a wide range of loads, so for the converters at light load and no The efficiency of loading time also puts forward high requirements. In this regard, the International Energy Agency (IEA), the United States, Europe and other countries and organizations have formulated or are formulating relevant standards to limit the loss of electrical products such as switch-mode converters at light load and no load. [0003] The series resonant DC / DC converter adopts resonant conversion technology, which can realize the zero-voltage turn-on of the switch tube, the power loss is very small, and the efficie...

AI Technical Summary

Problems solved by technology

[0011] Since the output voltage cannot be effectively controlled only by reducing the operating frequency in a resonant line, the first method is not applicable; the second method can improve the light-load efficiency to a certain extent, but when the converter operating frequency is high, the gain low (less than 1) (eg Figure 4 As shown), so the transmission energy in each working cycle is low, so the total number of switching times is still too much, and the switching loss and driving loss are still high, which cannot meet the increasingly stringent standards for light load loss restrictions

[0012] It can be seen that the above-mentioned existing control mechanism obviously still has inconvenience and defects, and needs to be further improved.

In order to solve the above problems, related fields have tried their best to find a solution, but no applicable method has been developed for a long time.

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