High-frequency isolated ac-dc converter with stacked architecture

Abstract

Abstract-This paper presents a new isolated ac-dc power converter achieving both high power factor and converter miniaturization suitable for many low power ac-dc applications. The proposed ac-dc converter architecture comprises a line-frequency rectifier, a stack of capacitors, a set of regulating converters, and a multi-input isolated bus converter. Among many suitable circuit implementations, the prototype system utilizes the resonanttransition buck converter as a regulating converter, and the capacitively-aided isolated bus converter for the isolated bus converter. The converter is miniaturized by operating at high frequency (1 -10 MHz range), and it buffers the ac-line frequency energy with a pair of stacked ceramic capacitors (1 µF and 150 µF, 100 V rating) without a requirement for electrolytic capacitors. The prototype converter is implemented to operate from 120 Vac to 12 V, and up to 50 W output as an example isolated ac-dc converter for power supply applications. The prototype converter demonstrates with 88 % efficiency and 0.86 power factor, and provides 50 W/in 3 power density, which is five times higher than the power density of typical conventional designs.

Minimum Active Switch Requirements for Single-Phase PFC Rectifiers Without Electrolytic Capacitors

“…9 also shows that fs_max in a Type II converter is generally much higher than that in a Type V converter with the same Po, c V , Cb and DCM inductor design. This is because fs in both (7) and (11) are proportional to d 2 . A type II converter, however, always has a dmax of 100%, while a type V converter has a dmax which can be designed small by increasing the ratio of c o V v .…”

High-Power-Density Single-Phase Three-Level Flying-Capacitor Buck PFC Rectifier

“…Single-phase power-factor-correction (PFC) rectifiers with simultaneous high power-density, high conversion efficiency and high reliability (H 3 ) are particularly desirable in many emerging applications such as LED driving (which requires a long service lifetime and a small form factor) [1]- [6] and quick charging for mobile phones (which demands a portable design and a high power efficiency) [7]- [9]. One critical challenge for conventional single-phase PFC rectifiers towards achieving H 3 is the use of electrolytic capacitors (E-caps) which are employed for buffering the double-line-frequency pulsing ripple power inherent in single-phase PFC rectifiers [10]- [14] (see Cb in Fig.…”

Design Considerations for Voltage Sensorless Control of a PFC Single-Phase Rectifier Without Electrolytic Capacitors

“…Based on the above discussions, a schematic diagram of the voltage sensorless controller that can estimate |𝑣 𝑎𝑐 |(t), vdc(t), and vc (t) using only the measurement of the inductor current iL is shown in Fig.2(b). Here the inductor current to voltage converter (ICVC) block is used to obtain a scale down and filtered inductor voltage vL signal (i.e., v''L) from iL; the demultiplexer is used to decode the switching inputs (SA, SB) to differentiate the switching states and to route the associated v''L (i.e., v''L,i) to one of the four amplitude modulation demodulator (AMD) channels; the AMD is used for envelop reconstruction; finally, the calculation block is used to process the envelop signals and yield all the voltage signals needed based on (5)-(8). Detailed design of the ICVC, the AMD, and other design considerations are discussed as follows.III.…”