High-efficiency AC/DC combined converter with wide output voltage range

Abstract

The invention relates to an alternate current / direct current (AC / DC) energy converter, and aims to provide a high-efficiency AC / DC combined convertor with a wide output voltage range. The convertor of the invention comprises a filter, a rectifier bridge B1, a Buck PFC circuit, an uncontrollable DC / DC circuit, an output filter capacitor Co and a parallel AC / DC circuit, wherein the filter is connected with the rectifier bridge B1; a control terminal of a switching tube S1 in the Buck PFC circuit is connected with the output of a Buck PFC control circuit; the Buck PFC control circuit is connected with the output of a feedback control circuit; the feedback control circuit comprises an error amplifier and a signal isolating circuit; and the output side of the output filter capacitor Co is sequentially connected with an output signal sampling circuit, the error amplifier and the signal isolating circuit. The invention acquires high efficiency and high power factors when isolation and the wide output voltage range are realized, improves the efficiency of the AC / DC convertor connected with the Buck PFC circuit in parallel, can solve the problem of too high starting up surge current of a boost power-factor correction (Boost) circuit, and does not need a surge current suppressing circuit, thus improving the efficiency.

Description

technical field [0001] The invention relates to an AC-DC power converter, in particular to a high-efficiency AC / DC combined converter with a wide output voltage range. Background technique [0002] Many AC / DC power conversion applications require a wide output voltage range, such as communication power supplies, battery chargers, LED drive power supplies, etc. The traditional AC-DC conversion scheme uses Boost as a rectifier circuit to output a constant voltage to obtain higher power factor and efficiency, and then follows a DC-DC converter with a wider output voltage range to supply power to the load. Since electrical isolation is required in many applications, isolated DC / DC is used in the latter stage. However, isolated DC / DC is difficult to optimize between high efficiency and wide output voltage. In order to meet the wide output voltage range, efficiency must be sacrificed. [0003] If the output voltage adjustment range of the boost is widened, although the efficienc...

AI Technical Summary

Problems solved by technology

However, the conversion efficiency of the Flyback is very low, and only if the power handled by the auxiliary converter is small, the impact on the overall efficiency is small

However, when the output voltage of the PFC is high and close to the peak value of the input voltage, Flyback needs to handle most of the power, and the overall efficiency becomes very low

Ordinary non-isolated boost circuit (Boost) cannot be directly connected in parallel with Buck PFC

There will be a contradiction between stepping up or stepping down, because the traditional Boost circuit cannot step down.

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