Power converter implementing frequency smearing

摘要

The present invention relates to a power converter (90) and a method of operating same. There are numerous advantages to operating power converters using a series resonant converter (1, 21). This approach is particularly suitable for minimizing switching losses in the power converter when it is operated at high frequency. However, there are problems with the known converters in that they are prone to generate noise in the acoustic spectrum due to the fact that the converter stages are often operating at different frequencies. The present invention relates to a power converter and a method of operating same that enables the operating frequency of the converter to be controlled by a control circuit over a predetermined range of the resonant frequency. This allows reduction in acoustic noise generation and facilitates frequency smearing that will in turn reduce spectral peaks. This is achieved while maintaining output ripple within acceptable ranges.

主权项

1. A power converter comprising a fixed ratio DCDC transformer section preceded by a pre-regulator section, wherein the fixed ratio DCDC transformer section further comprises an LLC resonant converter, and in which the operating frequency of the power converter is lower than the series resonant frequency of the LLC resonant converter and there is provided a control circuit operable to alter the operating frequency of the power converter over a limited range with respect to the resonant frequency in which a voltage/frequency characteristics is substantially flat wherein altering the frequency and that range will not cause a substantial increase in voltage.