Time filter

Source Type

Yamada S.,University of Tokyo | Awai K.,University of Tokyo | Hayato Y.,University of Tokyo | Kaneyuki K.,University of Tokyo | And 20 more authors.
IEEE Transactions on Nuclear Science | Year: 2010

The Super-Kamiokande detector is a ring imaging Cherenkov detector for neutrino physics and proton-decay search and consists of 50 000 tons of pure water equipped with about 13 000 photo-multipliers. The old front-end electronics and online system running for more than one decade were all upgraded in September, 2008 and the data acquisition was started successfully. The new front-end electronics is based on a charge to time converter and a multi-hit Time to Digital converter. TCP/IP based readout channel is implemented to handle large amounts of data. In the new data acquisition scheme, the hardware event-trigger for the data reduction is replaced by processing all the hits in the online farm, so that we are able to lower the threshold of the detection energy for solar neutrino and analyze consecutive events whose time interval is too long to detect in the previous system. To make the new online system to be capable of processing larger dataflow of up to 470 MB/s, we utilize Gigabit and 10-Gigabit Ethernet technologies and distribute the load over Linux PCs to handle a large amount of data. In this paper, we will describe the design and performance of the new system in the commissioning. © 2010 IEEE.


Shimizu T.,Tokyo Metroplitan University | Kakazu K.,Tokyo Metroplitan University | Matsumori H.,Tokyo Metroplitan University | Takano K.,IWATSU Test Instruments Corporation | Ishii H.,IWATSU Test Instruments Corporation
IEEE Energy Conversion Congress and Exposition: Energy Conversion Innovation for a Clean Energy Future, ECCE 2011, Proceedings | Year: 2011

This paper presents two methods of loss characterization of filter inductors used in PWM inverters of those developed by the authors, and verifies the results on both methods. The one is a loss-map-method, and the other is an ILA (Inductor Loss Analyzer)-method. The former method is useful for calculating the iron loss in the designing process of the converters, and the latter is useful for measuring the iron loss in a practical setup. By applying both methods, more accurate design and efficient verification will be available in designing high-power converters. Firstly, principles of two methods are briefly described. Next, comparison of both measurement results is made. The measured results were compared also with the one on a high precision power meter, and verified the accuracy of the ILA method. In some conditions, deviation between the loss-map method and the ILA method is observed, and proposed a method to improve the accuracy of loss calculation. An equation to describe frequency dependency of the iron loss with which the loss map method can be combined is also proposed. © 2011 IEEE.


Matsumori H.,Tokyo Metroplitan University | Shimizu T.,Tokyo Metroplitan University | Takano K.,Iwatsu Test Instruments Corporation | Ishii H.,Iwatsu Test Instruments Corporation
Electrical Engineering in Japan (English translation of Denki Gakkai Ronbunshi) | Year: 2015

In recent years, remarkable advancement of new power semiconductor devices, such as SiC and GaN, enables the increase of switching frequency of power converters, and hence the volume of passive components, such as ac filters and transformers, can be reduced. However, temperature rise caused by the inductor loss is increasing, and hence iron loss evaluation of the inductor is one of the most important issues to realize high power density converters. Conventionally, an improved generalized Steinmetz equation (iGSE) has proposed in order to calculate the iron loss under a pulse voltage magnetizing condition. However, accurate iron loss calculation of the ac filter inductor used in a PWM inverter cannot be realized. The authors have proposed two methods of iron loss evaluation of ac filter inductors. The first one is a loss map method which can calculate the iron loss without using a real PWM inverter. Another one is an ILA (Inductor Loss Analyzer) which can measure the iron loss in every switching period in a real PWM inverter. In this paper, comparisons of the iron loss between the ILA and the loss map method on both the single-phase and three-phase inverters are studied. It is found that iron loss of the ac filter inductor in the three-phase PWM inverter which is calculated by the loss map method cause a large error on a specific condition. In order to prevent the calculation error, the authors proposed a revised loss map method and proved the effectiveness of the method. © 2014 Wiley Periodicals, Inc.


Shimizu T.,Tokyo Metroplitan University | Kakazu K.,Tokyo Metroplitan University | Takano K.,Iwatsu Test Instruments Corporation | Ishii H.,Iwatsu Test Instruments Corporation
Electrical Engineering in Japan (English translation of Denki Gakkai Ronbunshi) | Year: 2015

Because of the improved performance of power devices, the volume of the ac filter inductors used in high-frequency PWM inverters has been reduced. However, the temperature rise in the filter inductor due to this miniaturization has become more pronounced. Therefore, we have proposed an iron loss calculation method for the ac filter inductor. However, the accuracy of the value calculated via the loss map method cannot be verified, because the iron loss arising during each switching period cannot be measured with conventional power measuring instruments. In order to resolve this problem, we developed an inductor loss analyzer (ILA), which allows precise measurement of the iron loss in the inductor during each switching period. The accuracy of the calculation of iron loss in the filter inductor by the loss map method was verified with the ILA. We found that the value calculated by the loss map method differed slightly from the value measured with the ILA. However, these differences can be reduced if we take into account the accurate flux density calculation and the effect of the duty ratio of PWM pulses on the loss. Finally, we verified that the loss map method can provide accurate iron loss calculations. © 2015 Wiley Periodicals, Inc.


Matsumori H.,Tokyo Metroplitan University | Shimizu T.,Tokyo Metroplitan University | Takano K.,Iwatsu Test Instruments Corporation | Ishii H.,Iwatsu Test Instruments Corporation
IEEE Transactions on Power Electronics | Year: 2016

The authors have proposed two methods for iron loss evaluation of the ac filter inductor used in a pulsewidthmodulation (PWM) inverter. The first method is a loss map method, which can be used for the iron loss calculation of the ac filter inductor without using a real PWM inverter, and the second method is an iron loss analyzer (ILA), which can measure the iron loss of the ac filter inductor during every switching period on a real PWM inverter. In this paper, the measurement results obtained using the ILA and the results calculated using the loss map method on both the singlephase and three-phase inverters are compared. The calculated iron loss of the ac filter inductor on the three-phase PWM inverter is found to have a relatively large error for certain PWM pulse conditions. In order to reduce the calculation error, the authors propose a modified loss calculation method and demonstrate that the calculation error is reduced to less than 2%. © 2015 IEEE.

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