New way to regulate DC link voltage for adaptive travel adaptor applications

Designing a single stage AC-DC converter operating at wide input and output is always a challenge for power engineers. As a general approach, designers typically use 2-stage configurations, such as employing a boost converter to pre-regulate DC link voltage to be constant... However, 2-stage solution is too complicate for low power applications. In addition the 2^nd stage DC-DC converter is fed from ~400V DC link, hence requires high voltage rated semiconductor devices for the 2^nd stage converter, which in turn affects DC-DC converter efficiency and cost. This paper presents a new way to regulate DC link voltage for wide input and output applications. Unlike conventional boost pre-regulator, the proposed regulation scheme is simple, and able to regulate DC link voltage to a desired line-independent low voltage level, e.g. 100V. Low DC link voltage enables adoption of lower voltage devices for DC link capacitors and 2^nd stage DC-DC converter to improve system efficiency, power density, light load & standby power, EMI, and reduce solution cost.