Interleaved resonant converter

#This invention relates to the field of power converters. More particularly, this invention relates to resonant power converters and interleaved resonant power converters, and methods and circuits for their control.

#With increasing power consumption of electronic devices there is a requirement for greater efficiency over the entire load range of power converters. While higher capacity power converters are desired, improving the light load efficiency is important because the light-load condition may constitute a substantial portion of the of the total converter usage time. However, the pursuit of higher power capacity is usually the priority in power supply design and consequently light load efficiency is sacrificed for higher power performance.

#The LLC resonant converter provides the highest efficiency for front-end DC/DC conversion, and it is becoming the predominant topology in many applications. To increase the power capacity of an LLC resonant converter, or to mitigate the current stress of the output capacitor, interleaving is used to parallel two or more LLC power stages [1-5]. It is expected that each LLC power stage is optimized for lower power, and a high overall output power is achieved by the total output of several LLC power stages.

#Embodiments of the invention are described below, by way of example, with reference to the accompanying drawings, wherein:

#FIG. 1(a) is a schematic diagram of a full-wave switch-controlled capacitor (fSCC) according to one embodiment;

#FIG. 1(b) is a schematic diagram of a half-wave switch-controlled capacitor (hSCC) according to one embodiment;

#Provided herein are full-wave and half-wave switch-controlled capacitor (SCC) resonant converters. In embodiments described herein, one or more full-wave or half-wave switch-controlled capacitor is used to control the resonant frequency of the converter, as an alternative or a supplement to the switching frequency modulation method.

#Also provided herein are interleaved SCC resonant converters having two or more resonant converter phases. The interleaved resonant converter phases may employ full-wave or half-wave switch-controlled capacitors. As described herein, switch-controlled capacitors are used to overcome load sharing problems associated with prior interleaved resonant converters. The methods and circuits provided herein enable interleaving of any number of resonant converter phases to expand power capacity of the power converter, and enable phase shedding to improve light load efficiency of the power converter. Embodiments include substantially constant switching frequency embodiments with, for example, full-wave SCC control (fSCC), which may be favourable in applications such as high-level system integration, and synchronized variable switching frequency embodiments with, for example, half-wave SCC control (hSCC). Such embodiments reduce component count and simplify the driving circuit, relative to embodiments with full-wave SCC control. Synchronized variable switching frequency fSCC and hSCC embodiments with a simplified master phase further reduce the component count.

#Methods and circuits using full-wave and half-wave switch-controlled capacitors described herein may be applied to various resonant power converter topologies, such as, but not limited to, series resonant converters, parallel resonant converters, LLC resonant converters, and LCC resonant converters. As noted above, the LLC resonant converter provides high efficiency for front-end DC/DC conversion, and is becoming the predominant topology in many applications. Therefore, LLC embodiments will be described herein. However, it is to be understood that the methods and circuits may be adapted to other resonant converter topologies.