Control characteristics improvement of full-bridge DC-DC converter with snubber capacitor

A high-voltage full bridge dc-dc converter has a big problem of high-voltage surge occurrence across secondary-side rectifying diodes. In order to solve this problem, a simple solution with a snubber capacitor has been proposed. This technique provides a prominent effect of surge-voltage suppression. On the other hand, it deteriorates the control characteristics of this converter. In this paper, the control characteristics are analyzed by the state-space averaging method. Based on this analytical result, the improvement of the control characteristics is proposed. Some experiments confirm the effectiveness of the proposed technique.7th International Power Electronics Conference, IPEC-Hiroshima - ECCE Asia 2014; Hiroshima; Japan; 18 May 2014 through 21 May 201

Integrated buck-boost converter with Matrix-POL architecture

In this study, integrated buck-boost converter with the Matrix-POL power supply system is proposed. From the simulation results, the validity of the Matrix-POL is revealed. The results revealed that the fast response to the load current and the voltage change can be done with duty and parallel number control by the proposed system.2013 15th European Conference on Power Electronics and Applications, EPE 2013; Lille; France; 2 September 2013 through 6 September 201

Frequency response analysis of proposed digital control system for DPWM-POL

This paper will discuss about the proposed hardware logic type digital controller for on-board SMPS which has a very small time-delay in control loop. Experimental results of the load current change experiment and the frequency characteristic of open loop transfer function has been described respectively. These results reveal the validity of the proposed technique.2013 15th European Conference on Power Electronics and Applications, EPE 2013; Lille; France; 2 September 2013 through 6 September 201

Switching surge reduction of a bi-directional dual active bridge DC-DC converter with a digital operation

Recently, the bi-directional dc-dc converter has been focused on because of the huge demand for diversification of power supply network including battery. The dual active bridge (DAB) dc-dc converter is one of the most popular circuits for bi-directional applications because of its simple structure. However, power efficiency at light load is the intrinsic problem of a bi-directional DAB DC-DC converter. In this paper, the simple solution with digital operation for the problem is proposed and experiments are performed with 1kW system. This method can reduce a switching surge without other circuits such as snubber and improve power efficiency at light load. Therefore it can reduce loss of switching surge, and improve power efficiency. From the results, 37% maximum power efficiency improvement at light load is confirmed. Furthermore, this method is capable for control in the conventional method in the heavy load range. Consequently, it is possible to reduce the switching surge and realize high power efficiency in a wide load range.2013 15th European Conference on Power Electronics and Applications, EPE 2013; Lille; France; 2 September 2013 through 6 September 201

A power efficiency improvement technique for a bi-directional dual active bridge DC-DC converter at light load

Recently, the bi-directional dc-dc converter has been focused on because of the huge demand for diversification of power supply network including battery. The dual active bridge (DAB) dc-dc converter is one of the most popular circuits for bi-directional applications because of its simple structure. However, power efficiency at light load is the intrinsic problem of a bi-directional DAB DC-DC converter. In this paper, the simple solution with digital operation for the problem is proposed and experiments are performed with 1kW system. This method can reduce a switching surge without other circuits such as snubber and improve power efficiency at light load. Therefore it can reduce loss of switching surge and, improve power efficiency. From the results, 37% maximum power efficiency improvement at light load is confirmed. Furthermore, this method is capable of control in the conventional method in the heavy load range. Consequently, it is possible to reduce the switching surge and realize high power efficiency in a wide load range.5th Annual IEEE Energy Conversion Congress and Exhibition, ECCE 2013; Denver, CO; United States; 15 September 2013 through 19 September 2013; Category numberCFP13ECD-US

Matrix-POL architecture for integrated power supply

In this study, integrated H-bridge converter with the Matrix-POL power supply system is proposed. From the simulation results, the validity of the Matrix-POL is revealed. The results revealed that the fast response to the load current and the voltage change can be done with duty and parallel number control by the proposed system.7th International Power Electronics Conference, IPEC-Hiroshima - ECCE Asia 2014; Hiroshima; Japan; 18 May 2014 through 21 May 201

Coinfection of Invasive Pulmonary Aspergillosis and Pneumocystis Jiroveci Pneumonia in a Non-HIV Patient

Invasive pulmonary aspergillosis (IPA) and pneumocystis jiroveci pneumonia (PCP) are life-threatening opportunistic infections that occur in immunocompromised hosts. Early diagnosis and treatment of these opportunistic infections is essential to the survival of immunocompromised patients. We report a 60-year-old man undergoing short-term steroid therapy after surgical resection of a brain tumor infected with combined invasive pulmonary aspergillosis and pneumocystis jiroveci pneumonia diagnosed by bronchoscopy with bronchoalveolar lavage. Our case demonstrated that short-term systemic steroid therapy in non-HIV patients with underlying chronic lung conditions and malignancies was a risk factor for IPA and PCP, and for a combination of these infections

5MHz PWM-controlled current-mode resonant DC-DC converter using GaN-FETs

In this paper, the method of the realization of a MHz level switching frequency DC-DC converter for high power-density is presented. For high power-density, Gallium Nitride field effect transistor (GaN-FET) and current-mode resonant DC-DC converter are adopted. In addition, the proposed pulse width modulation (PWM) control method which is suitable for the isolated current-mode resonant DC-DC converter operated at MHz level switching frequency, and the novel primary-side zero voltage switching (ZVS) turn on method for the proposed PWM control are presented. Some experiments have been done with 5MHz isolated DC-DC converter which has GaN-FET, and the total volume of the circuit is 16.14cm3. With the proposed PWM control method, input voltage range is 36-44V, and maximum load current range is 8A at Vi = 44V. The primary-side ZVS turn on is confirmed, and the maximum power-efficiency is 89.4%.7th International Power Electronics Conference, IPEC-Hiroshima - ECCE Asia 2014; Hiroshima; Japan; 18 May 2014 through 21 May 201