Toyama-shi, Japan
Toyama-shi, Japan

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Ishizuka M.,Toyama Prefectural University | Hatakeyama T.,Toyama Prefectural University | Funawatashi Y.,Toyama Prefectural University | Koizumi K.,COSEL Co.
Active and Passive Electronic Components | Year: 2011

In recent years, there is a growing demand to have smaller and lighter electronic circuits which have greater complexity, multifunctionality, and reliability. High-density multichip packaging technology has been used in order to meet these requirements. The higher the density scale is, the larger the power dissipation per unit area becomes. Therefore, in the designing process, it has become very important to carry out the thermal analysis. However, the heat transport model in multichip modules is very complex, and its treatment is tedious and time consuming. This paper describes an application of the thermal network method to the transient thermal analysis of multichip modules and proposes a simple model for the thermal analysis of multichip modules as a preliminary thermal design tool. On the basis of the result of transient thermal analysis, the validity of the thermal network method and the simple thermal analysis model is confirmed. © 2011 Masaru Ishizuka et al.


Koizumi K.,Cosel Co. | Hatakeyama T.,Toyama Prefectural University | Fukue T.,Iwate University | Ishizuka M.,Toyama Prefectural University
2014 International Conference on Electronics Packaging, ICEP 2014 | Year: 2014

Thermal flow simulation based on computational fluid dynamics (CFD) is applied to the thermal design of electronic equipment. This paper discusses the applicability of the multiple reference frame (MRF) approach, which is a new method for modeling an axial cooling fan, to the thermal flow simulation of electronic equipment. In this study, we performed flow visualization of the exhaust air flow pattern of the fan plane and then we compared the flow visualization results with the MRF fan model simulation results. Finally, comparing the P-Q characteristic which obtained by MRF fan model simulation with measured P-Q characteristic was conducted to validate the applicability of the MRF approach to the thermal flow simulation of electronic equipment.


Patent
Cosel Co. | Date: 2011-01-19

Provided is a switching power supply device that can limit the generation of recovery current of diodes connected in parallel between the two ends of a synchronized rectifying element by the addition of a simple circuit, and that improves efficiency and facilitates miniaturization. The device comprises a synchronized rectifying element (SR1) that turns on and off complementarily with a main oscillation element (TR1) that is connected in series with an input power supply (E), and a parasitic diode (DSR1) that is connected to the two ends of the synchronized rectifying element (SR1) in a direction enabling current supply toward a smoothing circuit (16). The device is equipped with a control circuit (PW2) that generates a control pulse with which is set the time delay for turning on the oscillation element (TR1) after a certain period of time after the synchronized rectifying element (SR1) is turned off has elapsed, and that drives the main oscillation element (TR1) and the synchronized rectifying element (SR1) based on the control pulse. An auxiliary rectification circuit (22) comprising a series circuit formed by an auxiliary switch element (Q1) and an auxiliary capacitor (C1) driven by the control circuit (PW2) is provided between the two ends of the parasitic diode (DSR1).


Patent
COSEL Co. | Date: 2012-07-25

A control circuit (24) includes a calculation means (28) which determines ON time and OFF time of a main switching element (14) and a drive pulse generating means (30) which generates drive pulses that turn the main switching element (14) ON and OFF. A control function formula which prescribes a relationship between an output voltage (Vo) and an output differential value (Vd) by a negative linear function and the like is defined in the calculation means (28). The calculation means (28) samples an input voltage signal (Vi) and an output voltage signal (Vo) at a timing synchronized with a switching cycle of the main switching element (14), and calculates the ON time and OFF time of the main switching element (14) thereafter so as to satisfy the control function formula. The drive pulse generating means (30) generates drive pulses (V14) which turn the main switching element (14) ON and OFF on the basis of the ON and OFF time determined by the calculation means (28).


Patent
Cosel Co. | Date: 2014-06-04

A control circuit (24) includes a calculation means (28) which determines ON time and OFF time of a main switching element (14) and a drive pulse generating means (30) which generates drive pulses that turn the main switching element (14) ON and OFF. A control function formula which prescribes a relationship between an output voltage (Vo) and an output differential value (Vd) by a negative linear function and the like is defined in the calculation means (28). The calculation means (28) samples an input voltage signal (Vi) and an output voltage signal (Vo) at a timing synchronized with a switching cycle of the main switching element (14), and calculates the ON time and OFF time of the main switching element (14) thereafter so as to satisfy the control function formula. The drive pulse generating means (30) generates drive pulses (V14) which turn the main switching element (14) ON and OFF on the basis of the ON and OFF time determined by the calculation means (28).


Patent
Cosel Co. | Date: 2010-10-25

A control function formula which provides a relationship between an output voltage signal Vo and an output differential value with, for example, a negative linear function is defined in a calculation means. The calculation means samples an input voltage signal, an output voltage signal and an output differential signal at time instants in synchronization with a cycle of switching of a main switching element, and calculates subsequent ON and OFF durations of the main switching elements such that the control function formula might be satisfied. A drive pulse generation means generates a drive pulse with which the main switching element is turned on and off based on the ON and OFF durations determined by the calculation means. The output differential signal is generated by, for example, a capacitor current detection means or an observer device which detect a current of a smoothing capacitor.


Patent
Cosel Co. | Date: 2010-08-11

A switching power source device includes current control pulse generating means 32 configured of a target value setting module 32a, which outputs a changeable value which is a predetermined target value relating to a control of an output current, a computing module 32b, which carries out a computing process relating to the control of the output current based on the target value, and outputs a computation result, and a pulse generating module 32c, which generates a current control pulse voltage for controlling the output current based on the computation result. The switching power source device includes a current detecting circuit 38, which detects the output current or a current flowing in a switching element TR1, and a current limit signal generating circuit 36 which, when the detected current exceeds a reference value set based on the output of the current control pulse generating means 32, outputs a current limit signal for limiting the current. A drive pulse generating circuit 18, on the current limit signal being output, operates in such a way that an on-duty of a drive pulse stops widening, or becomes narrower.


Eco

Trademark
COSEL Co. | Date: 2011-05-18

High-frequency switching power supplies; apparatus for power factor correction; power supply converters; switching regulators; power line filters; apparatus and instruments for regulating or controlling electric current.


Trademark
COSEL Co. | Date: 2011-01-18

High-frequency switching power supplies; apparatus for power factor correction; power supply converters; switching regulators; power line filters.


Fukue T.,Iwate University | Hirose K.,Iwate University | Hatakeyama T.,Toyama Prefectural University | Ishizuka M.,Toyama Prefectural University | Koizumi K.,Cosel Co.
2016 International Conference on Electronics Packaging, ICEP 2016 | Year: 2016

This paper describes the details of pressure drop characteristics around axial cooling fans mounted in high-density packaging electronic equipment in order to improve prediction accuracy of supply flow rate of the fans in thermal design. Forced air convection cooling driven by cooling fans is the commonest strategy for dissipating heat from electrical devices. Cooling performance of the fans is mainly decided by supply airflow rate. The supply flow rate is strongly affected by pressure drop characteristics in electronic equipment. Especially in the case of high-density packaging electronic equipment, the airflow around the fan generally becomes complex and an accurate prediction of pressure drop characteristics around the fans become significantly difficult. In addition, due to the change of the airflow pattern around the fans by the electrical components mounted near the fans, a deterioration of fan performance itself is sometimes caused. Hence the accurate prediction of supply flow rate of the fans in high-density packaging electronic equipment is generally difficult. However, in order to shorten the period of thermal design, more detailed investigation about airflow characteristics around the fans mounted in high-density packing electronic equipment should be done in order to achieve the accurate prediction of fan's supply flow rate easily. We are trying to develop a prediction model of accurate supply flow rate of the fans mounted in high-density packaging electronic equipment. In this report, the pressure drop characteristic near the axial fan when an obstruction, which simulates electrical components mounted near the fans, is mounted in front of the fan was evaluated while changing the type of the obstruction. The pressure drop around the fan with the obstruction is mainly composed of three factors; the pressure drop around the obstruction, the inlet pressure drop at the fan and the outlet pressure drop from the fan. A level of these pressure drop factors were evaluated quantitatively by comparing experimental results with the conventional pressure drop database. In order to evaluate the accurate supply flow rate of the fan in high-density packaging electronic equipment, an important factor was clarified from the viewpoint of the pressure drop characteristics around the fans. © 2016 The Japan Institute of Electronics Packaging.

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