1,721,350 research outputs found
Instabilities in Silicon Power Devices: A Review of Failure Mechanisms in Modern Power Devices
No full textSimultaneous On-State Voltage and Bond-Wire Resistance Monitoring of Silicon Carbide MOSFETs
Full text linkIn fast switching power semiconductors, the use of a fourth terminal to provide the reference potential for the gate signal—known as a kelvin-source terminal—is becoming common. The introduction of this terminal presents opportunities for condition monitoring systems. This article demonstrates how the voltage between the kelvin-source and power-source can be used to specifically monitor bond-wire degradation. Meanwhile, the drain to kelvin-source voltage can be monitored to track defects in the semiconductor die or gate driver. Through an accelerated aging test on 20 A Silicon Carbide Metal-Oxide-Semiconductor-Field-Effect Transistors (MOSFETs), it is shown that there are opposing trends in the evolution of the on-state resistances of both the bond-wires and the MOSFET die. In summary, after 50,000 temperature cycles, the resistance of the bond-wires increased by up to 2 mΩ, while the on-state resistance of the MOSFET dies decreased by approximately 1 mΩ. The conventional failure precursor (monitoring a single forward voltage) cannot distinguish between semiconductor die or bond-wire degradation. Therefore, the ability to monitor both these parameters due to the presence of an auxiliary-source terminal can provide more detailed information regarding the aging process of a device
Self-Sustained Turn-OFF Oscillation of Cascode GaN HEMTs:Occurrence Mechanism, Instability Analysis, and Oscillation Suppression
Full text linkThis article presents a comprehensive study on the occurrence mechanism, instability analysis, and suppression methods of self-sustained turn-off oscillation, which occurs on cascode gallium nitride high electron mobility transistors (cascode GaN HEMTs). In the beginning, the oscillation waveforms are analyzed, which indicate that the occurrence of the oscillation is determined by test circuit instability. Based on the double pulse test, the impact of the load current I_L, dc bus voltage V-{text{DC}} and gate resistance R-{G} on the self-sustained oscillation is identified. To investigate the instability of the resonant circuit, a small-signal ac model of the resonant circuit is derived. Based on the model, the influences of various parameters on the self-sustained oscillation are analyzed. The analyses reveal the possible methods which can suppress the oscillation. The effectiveness of the proposed methods is validated by the experimental data and simulation results in the end. </p
Unclamped repetitive stress on 1200 V normally-off SiC JFETs
No full textAn experimental characterization of new-generation normally-off vertical channel 1200 V SiC JFETs
under unclamped repetitive stress (URS) is presented. The drain and gate leakage currents are monitored,
and their time evolution is recorded.
The degradation of the leakage characteristics has been compared with repeated short circuits tests, at
the same stress energy, thus demonstrating that different mechanisms take place in these conditions.
Furthermore, a post-failure analysis of the surface of the device by means of a optic microscope indicates
that a termination weakness could be the major cause for the device leakage increment and consequent
failure
Online Junction Temperature Extraction for Cascode GaN Devices Based on Turn-On Delay
No full textWe introduce an innovative method for online junction temperature monitoring in cascode gallium nitride (GaN) devices, utilizing turn-on delay as the temperature sensitive electrical parameter for the first time on this device. The turn-on process is analyzed, and the expression of turn-on delay is derived, pointing out the factors affecting the turn-on delay. Following that, we provide a circuit implementation, along with an explanation of its operational principles. Thanks to the high resolution of the proposed method, a large auxiliary gate resistor used to improve the sensitivity is avoided. Furthermore, the avoidance of large gate resistors prevents triggering the self-sustained oscillations of cascode GaN devices. Finally, a comprehensive experimental verification is carried out. The results show that the proposed method has a short response time of 500 ns, a small static error of 2.3 °C and good dynamic performance. Besides, a dc power cycling was conducted to prove that the accuracy of the proposed method is not affected by device aging, proving its feasibility and applicability in practical applications
In-Operation Junction Temperature Extraction for Cascode GaN Devices Based on Turn-Off Delay
Full text linkIn this article, a method to extract the junction temperature of cascode gallium nitride (GaN) devices based on the turn-off delay is proposed for the first time, together with a possible circuit implementation. We described the method theory at first, which showed good applicability even at low gate-resistor values, allowing avoidance of self-sustained oscillations and extra losses. The circuit implementation has also been presented starting from the design process and ending with a comprehensive experimental campaign. The experimental results show both a good static and dynamic performance and a high repeatability within 0.6 °C. The overall obtained accuracy stays within ±2 °C and the response time is 500 ns, besides, the test results from dc power cycling shows that the accuracy of proposed method will not be affected by aging
Accuracy estimation of low-current voltage drop method for junction temperature monitoring under DC power cycling
Full text linkA thorough accuracy estimation of the well-known low-current voltage drop method is carried out in this paper. A high-performance infrared camera is utilized as the reference in a DC power-cycling test on a commercial IGBT power module. The result shows that the low-current voltage drop method produces generally a higher temperature than the actual, in particular at the bond wire's joint point. However, a simple compensation method with a linear function can be easily adopted to compensate the temperature difference. After compensation, the maximum error of temperature swing is 0.28 °C.</p
Design of a Non-destructive Device Test Platform Capable of Double-pulse Tests and Short-circuit Tests with Fast Overcurrent Protection for Wide Band-gap Devices
No full textObtaining the characteristics of the device is a key procedure before practical applications. Here in this paper, the design of a device test platform for wide-bandgap devices is introduced. The platform has a high noise immunity, low loop inductance, and fast overcurrent protection, realizing a non-destructive operation.</p
Measuring Temperature Swing with Optical Fibers during Power Cycling of Power Components
Full text linkPower semiconductor components play an important role in the power electronics field and their reliability and lifetime have been attracting more and more attention recently. The power cycling test method has been widely used to accelerate the degradation of the device and evaluate its reliability and lifetime. This paper presents a power cycling setup based on optical fibers to measure the power module's chip junction temperature during operation under different loading conditions. The setup has been used to conduct both the DC- and AC- power cycling tests, and the junction temperature measured by the optical fibers during the tests can help to evaluate the thermal stress during operation, indicate the health status of the device under test (DUT) and record its degradation process. Experimental results verified that implementing optical fibers is an effective way of measuring the junction temperature while conducting the accelerating test
Thermal Mapping of Power Modules Using Optical Fibers during AC Power Cycling Tests
No full textThe power cycling withstand capability of power semiconductors is of great interest in determining the component's qualification and reliability performance. Compared to the traditional DC Power cycling test, the AC power cycling test can accelerate the component to fail under more realistic operating conditions. The wear process in the AC power cycling test depends on many parameters, among which the maximum junction temperature TJ, and temperature swing ΔTj are crucial to be determined. The traditional way in DC power cycling test is to measure the Tj indirectly using the temperature-sensitive electrical parameter (TSEP) method, which is not very applicable during the AC power cycling test as it will increase the circuit complicity and may interrupt the PWM operation. The purpose of this paper is to evaluate a direct junction temperature measurement in an IGBT power module through silicone gel using optical fibers, which enables a fast and accurate Tj determination during AC power cycling. For this purpose, junction temperatures have been measured for both gel-filled modules and gel-removed modules under different experimental conditions. The experimental results presented concern about: the presence of silicone gel's impact on the TJ measurement accuracy, the temperature difference inside the silicone gel while the optical fiber is being instrumented at different positions, and the spatial temperature distributions of the IGBT chip. Future work will also include the comparison of the TJ measurements of a gel-filled power module between using the optical fibers and the well-established TSEP method.</p
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