Yasuhiro Okuma

Design, Modeling, and Improvement of Integrated EMI Filter With Flexible Multilayer Foils

Integrated electromagnetic interference (EMI) filter design method with flexible multilayer (FML) foils is presented. An analysis model for integrated EMI filter with FML foils, distributed electromagnetic component (DEMC) model, is proposed. The DEMC model is verified by the experiment. In addition, method to improve the high-frequency performance of integrated EMI filter is investigated. Prototype of integrated EMI filter with FML foils is made for 1 kW switching power supply. In comparison with the traditional discrete EMI filter, it can reduce total volume by 45%.

Integrated EMI filter design with flexible PCB structure

A novel integrated EMI filter structure is proposed in this paper, based on the flexible PCB integrated L-C winding. By employing this integrated L-C structure, CM inductors, DM inductors and CM capacitors are integrated in a single unit. By compare with the planar PCB winding that used in previously proposed method for integrated EMI filters, we found that flexible PCB winding need less length, which means less loss and room. A prototype was built, and measurement result presented.

Utilizing Flexible Printed Circuit Board (FPCB) to realize passives integration in LLC resonant converter

There are altogether four passive components in the resonant tank of LLC resonant converter: the series resonant inductor, the resonant capacitor, the parallel inductor and the transformer. A new method utilizing the flexible printed circuit board (FPCB) to realize passives integration in LLC resonant converter is presented. The design process is provided, and the experimental results verify its feasibility. However, due to the severe high frequency loss of the dielectric material used in FPCB technique, the converter efficiency decreases greatly at heavy load condition after the resonant capacitor is integrated, and the switching frequency range to realize output voltage regulation against load variation also becomes wider. We use another two kinds of dielectric material with better characteristic replace the substrate dielectric material in FPCB technique, then the efficiency improves and the switching frequency range shrinks. As a result, the fully integrated structure can reduce the total passive components size by 36% compared to the discrete structure with even better performance. Hence the power density is increased remarkably.

An integrating structure of EMI filter based on interleaved flexible multi-layer (FML) foils

A novel integrated EMI filter structure is proposed in this paper, based on FML foils. It integrates common mode inductors and differential mode capacitors and inductors into a single unit. A novel interleaved flexible multi-layer (FML) foil structure is proposed to overcome the difficulty of enlarging the DM capacitance. A prototype is constructed based on this concept and was put into a front-end converter to replace a discrete EMI filter. Testing result presented.

Direct linked type frequency changer based on DC-clamped bilateral switching circuit topology

This paper describes a direct linked type frequency changer (hereafter called DLT-FC) proposed by the authors. The DLT-FC is a converter circuit with a new configuration for direct frequency change. The DLT-FC does not require a DC link circuit, nor bilateral switches. In addition, DC snubber circuits can be applied without the need for a regenerative circuit of snubber energy. Therefore, the DLT-FC can be designed to be compact and lightweight, and have a long life. The authors made a prototype of the DLT-FC and experimentally checked its operation. The results indicate that the performance of the DLT-FC makes it suitable for industrial use.

Impact of dielectric material on passive integration in LLC resonant converter

In this paper, a transformer structure integrating three resonant tank components C_s, L_s, and L_p of the LLC resonant converter is proposed and implemented. For the structure, the analysis and calculation of C_s as well as the calculation and design of L_s and L_p is introduced in detail. In the verification experiments, two kinds of dielectric materials are applied. They result in different performances. The experimental results include the efficiency, the switching frequency, and the temperature rise.

Design and experiment research of integrated EMI filter based on flexible multi-layer foils

A novel passive integration structure based on flexible multi-layer foils was proposed for EMI filter in switching-mode power supply. Common mode (CM) inductors and capacitors, differential mode (DM) inductors and capacitors were all integrated in a single unit. This passive integration applied flexible multi-layer foils (FML). Prototypes were implemented for an 1kW switching power supply. The conductive EMI testing result was presented. The temperature rising and efficiency curves of the integrated EMI filter were also presented. In comparison with the discrete EMI filter, the prototype in this paper can reduce the volume by 32%.

Modeling of integrated EMI filter with flexible multi-layer (FML) foils

A model of Distributed Electromagnetic Component (DEMC) for integrated EMI filter based on FML foil is proposed in this paper. The model is used for estimating the insertion loss of integrated EMI filter with FML foils. In this model, distributed parameters such as parasitic capacitance, magnetic coupling between conductors, core loss, copper loss, dielectric loss of the magnetic core are all included. Prototype was built. The model is verified by the experiment.

A DC power supply using flying-capacitor three-level PFC and LLC resonant three-level DC/DC converter for wide input-voltage range and multi output

In this paper, a DC power supply for wide input-voltage range and multi output, which is applied to both 200-V and 400-V power sources, is proposed. This power supply consists of a flying-capacitor three-level PFC and a LLC resonant three-level DC/DC converter. In the PFC, the circuit topology enables to use 600-V devices, minimize the detection circuit and the gate drive circuit, and reduce the size of the AC inductor. In addition, 600-V devices are adopted by the three-level topology in the DC/DC converter. The multi output consists of triple 24-V outputs and single 12-V output. The performance of the proposed DC power supply is evaluated by the experiment. The experimental results show that the efficiency reaches more than 88% at both AC 200-V and 400-V inputs. This efficiency is quite high for DC power supplies with wide input-voltage range and multi output.

An isolated medium-voltage AC/DC power supply based on multil-cell converter topology

This paper discusses an isolated medium voltage AC/DC power supply based on multi-cell converter approach for an information and telecommunication (IT) system. A multi-cell converter approach can reduce number of conversion stage by accepting medium-voltage (MV) input directly. Thus, IT system can reduce total size. In addition, due to applying high frequency transformer to converter cells, it is possible to achieve downsizing and isolation of power supply. A prototype of isolated MV AC/DC power supply, for 2.4 kV input and 54 V output, is realized and evaluated at the rated output power load of 25 kW. As a result, the total efficiency of 96% at rated power is confirmed.