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High reliability is required for power modules because they are increasingly demanded as key devices in an energy-saving society. However, commercially available current sensors like current transformers and Rogowski coils are still of large size. Therefore, it is impossible to measure the current in small parts. In addition, long wiring with large sensors reduces the performance of power modules. In previous studies, we proposed a current sensor of PCB Rogowski coil with a fishbone pattern. The sensor is sufficiently small and thin with high accuracy for power module application. The PCB current sensor can be used as a built-in current sensor in power modules from the viewpoint of size. However, the sensor requires further improvement to be attached to bonding wire from a usability perspective. We propose a new pattern for the clamp-type PCB sensor and fabricate the PCB sensor as a built-in sensor in a power module. With the new pattern, it is possible to move and widen the gap for clamping. The signal error is small even though the sensor is inclinedly attached to the bonding wire. The accuracy is confirmed by a comparison between the clamp-type PCB sensor in the module and a commercially available current sensor outside the module. The clamp-type PCB sensor can be applied for intelligent power modules as well as current measurement for power electronic converters. [ABSTRACT FROM AUTHOR]

We have developed a printed circuit board Rogowski coil for monitoring of current and protection of high-voltage power modules and packages. It is small, thin, and inexpensive current sensor and is almost the ideal Rogowski coil because of its fishbone pattern. For noise reduction under high-voltage/-current conditions in a module, shield layers and coaxial connector are employed. In addition, a new, fast simulation tool was developed to optimize the main coil pattern for realization of arbitrary printed circuit board geometry in specific, limited spaces. [ABSTRACT FROM AUTHOR]

Current crowding of IGBT and power diode in a chip or among chips is a barrier to the realization of highly-reliable power module and power electronics system. Current crowding occurs because of the parasitic inductance, difference of chip characteristics or temperature imbalance among chips. Although current crowding among IGBT or power diode chips has been analysed on numerical simulations, no sensor with sufficiently high special resolution and fast measurement time has yet been demonstrated. Therefore, the author developed and demonstrated 16-channel flat sensitivity sensor array for IGBT current distribution measurement. The sensor array consists of tiny-scale film sensors with analog amps and shield case against noise. The array and digital calibration method will be applied for reliability analysis, designing and screening of IGBT modules. [ABSTRACT FROM AUTHOR]

We developed a high-throughput screening tester for DBC-module of IGBT. The tester realizes a new screening test with current distribution in addition to a conventional switching test. It consists of a power circuit, a replaceable test head, sensor array module and digitizer with LabVIEW program. Therefore, all kinds of DBC-modules can be screened by switching the test head. The tester acquires magnetic field signals and displays GO/NOGO judgment automatically after digital calibration and signal processing in 10 s. It is expected to be applied for screening in a production line and analysis in order to prevent the failure of power modules. [ABSTRACT FROM AUTHOR]

The aim is to provide failure analysis of power devices based on real-time monitoring. The real-time monitoring provides a time-domain data related to a failure mechanism. The data includes important information about primary failure, which is often lost by conventional post-defect failure analysis. Our system monitors interfaces of component material inside the device by scanning acoustic tomography (SAT) under a power cycling test in addition to electrical and thermal condition of the device. A precursor of the failure in an early stage was indicated by the interface image much earlier than a thermal and an electrical technique. Feature identification and extraction from a series of image data by image processing efficiently pointed out the damaged site before the failure was occurred. [ABSTRACT FROM AUTHOR]

Abstract: Avalanche induced oscillation phenomena during reverse recovery of power PiN diodes are investigated for the purpose of “Design for EMI”. The oscillation phenomena are the major barrier to improve power diode performance since the oscillation can cause serious EMI, affecting power electronics system reliability. The mechanism of the oscillation is precisely modelled under various diode structures and current ranges. The result will contribute to the design methodology to attain stable yet high performance diodes and power electronics systems. [Copyright &y& Elsevier]

Abstract: Aim: To measure HPV status, epidermal growth factor receptor (EGFR) and transforming growth factor-α (TGF-α) expression and Ki-67 index in exophytic papilloma (EP), inverted papilloma (IP) with dysplasia, IP with carcinoma and invasive squamous cell carcinoma (SCC). Methods: Forty-four patients with sinonasal papilloma and invasive SCC were selected. The nasal tissues were stained with monoclonal antibodies to EGFR, TGF-α and Ki-67. The results were analysed using quantitative immunohistochemical analysis. In situ hybridization studies for HPV DNA for 6/11, 16/18 and 31/33 were also performed on the tissue. Results: Significant increase of EGFR and TGF-α was observed in IP with severe dysplasia, IP with carcinoma and invasive SCC compared to IP with mild dysplasia and control nasal mucosa. And a serial upreguration in terms of Ki-67 index in IP with dysplasia was observed. Among IP, HPV 6/11-positive was present in 42% tumour and HPV 16/18-positive was present in 31% of tumours. Among HPV 6/11 and 16/18-positive IP, significant increase of EGFR and Ki-67 index were observed. Conclusion: Pre-cancerous lesions of IP exhibited elevated levels of EGFR and TGF-α and these expression may be associated with early events in IP carcinogenesis. HPV infection may be an early event in a multistep process of malignant formation of IP. [Copyright &y& Elsevier]

Abstract: Aims: To compare the effectiveness of induction chemotherapy with docetaxel, cisplatin and 5-fluorouracil (TPF) followed by radiation with that of concurrent chemoradiotherapy with TPF in patients with locally advanced squamous cell carcinoma of the head and neck (SCCHN). Materials and methods: In a group of patients receiving induction chemotherapy followed by radiation, 15 patients received two cycles of chemotherapy with docetaxel 60mg/m2, cisplatin 70mg/m2 and 5-day 5-fluorouracil (5-FU) 750mg/m2/day. Radiotherapy was begun 21 days after completing chemotherapy. In the group receiving concurrent chemoradiotherapy, 19 patients received two cycles of chemotherapy with docetaxel 50mg/m2, cisplatin 60mg/m2, and 5-day 5-FU 600mg/m2/day. Radiation was begun on the first day of chemotherapy. The total radiation dose was between 63 and 74Gy. Results: Overall response rate (partial and complete response — both 100%) and complete response rate (87% and 84%) were similar, but, in overall survival, concurrent chemoradiotherapy with TPF was better than induction chemotherapy with TPF followed by radiation. Mucositis and anaemia were more frequent in the group receiving concurrent chemoradiotherapy, but the group receiving concurrent chemoradiotherapy with TPF improved overall survival. Conclusions: This is a small non-randomised comparison. The effectiveness of concurrent chemoradiotherapy with TPF was better than that of induction chemotherapy with TPF followed by radiation. [Copyright &y& Elsevier]

The non-uniform current sharing among the paralleled devices is consequential due to non-identical layout and alteration in parameters of the system consists of power semiconductor devices and gate drivers. The persistent non-uniform current among the paralleled devices arise the various concerns such as de-rating, uneven losses, and heat consequently can lead to reliability and failure issues of the system. This paper presents a simple yet intelligent and effective automatic control for gate delay compensation to achieve active current balancing through current peak minimisation. The current peak minimisation control approach can serve the purpose of minimising system de-rating as well as obtaining nearly uniform dynamic current sharing. The four parallel connected discrete IGBT system is used for experimental validation under unbalanced operating condition. Moreover, the current peak minimization trend evaluation is introduced for gate delay compensation. • Parallel operation of power devices for high current power system and unbalancing problem associated with the system. • A gate delay compensation concept based on peak minimization is presented. • The control using peak minimization concept is to achieve current balancing as well as peak overshoot optimization. • The control mehod capable of adjusting gate delay for turn-on and turn-off indepdendlty corresponding to unbalancing. • The gate delay compensation method is experimentally validated for four parallel connected discrete IGBT devices. [ABSTRACT FROM AUTHOR]

The shoot-through phenomenon has not been fully discussed for high-power inverters with IGBTs. This is because a negative gate voltage is applied to IGBTs during off states. Recently, attention is paid to an improved gate driver with only a positive gate voltage in order to meet demands for simplification, integration, and reduction in power consumption as well as in cost of the gate driver. Moreover, the threshold voltage of the next-generation IGBT will decrease with microfabrication techniques of the gate structure. This will make the shoot-through phenomenon severer and degrade the inverter reliability with the next-generation IGBTs. The influence of the parasitic parameters in both the IGBT and circuit on the shoot-through mechanism has not been investigated so far. This paper clarifies the shoot-through mechanism and investigates the impact of the next generation IGBTs on the inverter reliability. The influence of the internal capacitance of IGBT including stray inductance on inverter reliability is experimentally confirmed. [ABSTRACT FROM AUTHOR]

Compact model for expressing turn-off waveform for advanced trench gate IGBTs is proposed even under high current density condition. The model is analytically formulated only with device structure parameters so that no fitting parameters are required. The validity of the model is confirmed with TCAD simulation for 1.2–6.5 kV class IGBTs. The proposed turn-off model is sufficiently accurate to calculate trade-off curve between turn-off loss and saturation collector voltage under extremely high current conduction, so that the model can be used for system design with the advanced trench gate IGBTs. [ABSTRACT FROM AUTHOR]

AimsTo identify the relationship between p21 and p53 expression, human papilloma virus (HPV) infection and malignant transformation in sinonasal-inverted papilloma.Material and methodsNasal tissues, exophytic papilloma, inverted papilloma (IP) with dysplasia, IP with carcinoma and invasive squamous cell carcinoma (SCC) were stained with the monoclonal antibodies p21 and p53. In-situ hybridisation for HPV DNA was also carried out for types 6/11, 16/18 and 31/33.ResultsSignificant increased staining of p21 and p53 was observed in IP with severe dysplasia, IP with carcinoma and invasive carcinoma compared with control nasal mucosa. A significant increase of dysplasia was observed in IP in the HPV 6/11 and 16/18-positive group, compared with the HPV 6/11 and 16/18-negative group. Significant decrease in expression of p21 and p53 was observed in HPV 16/18-positive IP compared with HPV 16/18-negative IP.ConclusionsOur data raise the possibility that testing for p21, p53 and HPV may help to screen out papilloma lesions with a potential for dysplasia or carcinoma. [ABSTRACT FROM AUTHOR]

Attention has been paid to the next-generation IGBT toward CMOS compatible wafer processes, which can be driven by a 5-V logic level due to its low threshold gate voltage. This low threshold voltage makes the so-called shoot-through fault severer. Even though the switching speed of the IGBT is intentionally reduced, the shoot-through fault can happen. This paper presents shoot-through protection for an inverter consisting of the next-generation IGBTs with gate impedance reduction. Theoretical analysis reveals the criterion of the gate impedance with taking parasitic parameters of the inverter into account. [ABSTRACT FROM AUTHOR]

Increase of power bus voltages in spacecraft are expected with the power demand growth. Accordingly, high voltage semiconductor devices in the power supply system will be required to withstand high energy and high flux cosmic ray environment. In this paper, we propose a new formula to calculate failure rate for power semiconductor devices in space application. • Single event burnout failure rate for satellite orbit • SEB cross-section of power semiconductor by TCAD simulation • A universal calculation method of failure rate for irradiation condition [ABSTRACT FROM AUTHOR]

This paper proposes a new short-circuit protection method for an IGBT. The proposed method is characterized by detecting not only gate charge but also gate voltage of the IGBT. This results in a shorter protection time, compared to the previous method that detects only the gate charge. A real-time monitoring system using an FPGA, A/D converters, and a D/A converter is used for the proposed protection method. Experimental results verify that the proposed method achieves a protection time of 390 ns, which is reduced by 68% compared to the previous method. [ABSTRACT FROM AUTHOR]

The higher current density of IGBTs has made it difficult to achieve high short-circuit withstand capability as well as good conduction characteristics. Therefore, a fast and reliable protection system is required for the safe operation of IGBT. This paper determines the short-circuit safe protection area (SCSPA) for advanced IGBT that has no short-circuit withstand capability and proposes the protection system satisfied this SCSPA. The fast protection is brought by PCB Rogowski coil and digital gate driver using digital circuit (FPGA). Experimental results verify that short-circuit detection time is 70 ns, shut-down time is reduced by controlling the gate resistance at turn-off. [ABSTRACT FROM AUTHOR]