This paper suggests an isolated dc/dc converter using an unregulated LLC converter for fuel cell applications. The LLC converter operates as an isolated voltage amplifier with a constant voltage gain, and a nonisolated converter installed in the input stage regulates the output voltage under a wide variation of fuel cell stack voltage. By separating the functions, the unregulated LLC converter ...

The flying-capacitor (FC) topology is one of the more well-established ideas of multilevel conversion, typically applied as an inverter. One of the biggest advantages of the FC converter is the ability to naturally balance capacitor voltage. When natural balancing occurs neither measurements, nor additional control is needed to maintain required capacitors voltage sharing. However, in order to ...

This application note describes a 150W rating design guideline for LED street lighting. The application design consists of CRM PFC and LLC SRC with high power factor and high power conversion efficiency using FL7930B and FAN7621S. To verify the validity of the application board and scheme, a demonstration board 150W (103V/1.46A) AC-DC converter was implemented and its results are presented in t...

This paper introduces a cutting-edge transformer technology – the piezoelectric transformer – currently considered as a potential candidate to replace magnetic transformers in resonant switching converters. Magnetic transformers are extensively used for providing step-up and step-down voltages while allowing input to output isolation in ac-dc and dc-dc converters. Even with the extensive use, t...

This paper introduces a new bidirectional, isolated dc–dc converter. A typical application for this converter can be found in the auxiliary power supply of hybrid electric vehicles. A dual half-bridge topology has been developed to implement the required power rating using the minimum number of devices. Unified zero-voltage switching was achieved in either direction of power flow with neither a...

In this work, an LCL-type resonant dc/dc converter with a capacitive output filter is modeled in two stages. In the first high-frequency ac stage, all ac signals are decomposed into two orthogonal vectors in a synchronous rotating d–q frame using multi-frequency modeling. In the dc stage, all dc quantities are represented by their average values with average state-space modeling. A nonlinear tw...

A novel model based methodology is presented to determine optimal device parameters for the fully integrated ultra low voltage DC-DC converter for energy harvesting applications. The proposed model feasibly contributes to determine the maximum efficient number of charge pump stages to fulfill the voltage requirement of the energy harvester application. The proposed DC-DC converter based power c...

The resonant power conversion having many advantages over conventionally adopted pulse width modulation that includes a high efficiency, low electromagnetic interference, small volume, low switching losses, and light weight of components due to a high switching frequency, and low reverse recovery losses in diodes owing to a low di/dt at switching instant. This paper presents the doubly loaded r...

Abstract – A novel parallel three-level zero voltage switching (ZVS) DC converter is presented for medium voltage applications. The proposed converter includes three sub-circuits connected in parallel with the same power switches to share load current and reduce the current stress of passive components at the output side. Thus, the size of the output chokes is reduced and the switch counts in t...