5,280 research outputs found
Large-Scale Adoption of Silicon Carbide in the Automotive Sector: What is Missing?
No full textThis paper tackles the hurdles hindering the adoption on a large scale of silicon carbide in power electronics, especially in the automotive sector. The main point is that a lack of knowledge in terms of reliability as well as the intrinsically poor short-circuit withstanding capability make the present largely uncertain, and the adoption of the SiC technology is consequently delayed. The conclusion is that cost-breaking actions by the big world players will soon lower the cost, although never at the silicon level, but sufficiently to eventually activate dynamic sectors like the automotive one in the coming 4-5 years
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
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
Junction temperature monitoring for cascode GaN devices using the Si MOSFET's body diode voltage drop
Full text linkIn this paper, a new online junction temperature monitoring method is proposed for cascode GaN devices using the body diode of Si MOSFET. The reverse current during soft-switching mode is utilized to extract the voltage drop of the Si MOSFET's body diode. It is pointed out that, to accurately obtain the voltage drop of Si MOSFET's body diode, the VDS voltage of cascode GaN device should be measured when the reverse current is small during the dead-time period. An experimental platform has been designed to validate the proposed method. The proposed method exhibits an accuracy within 0.6 °C and a R2 = 0.99 goodness of linear fit on a test Buck converter, showing that this method is practical for real applications.</p
Factors Affecting Self-Sustained Switching Oscillations of Cascode GaN Devices and Mitigation Strategy during Parameter Design
No full textWith the fast development of wide band-gap devices, GaN is occupying a larger market than before. As one of the commercial devices, cascode GaN has shown several advantages. However, its cascode configuration brings oscillation problems. Although some related research has been done, comprehensive experimental tests to analyze the factors affecting self-sustained oscillations have not been conducted so far. In this paper, it is the first time that the effects of gate resistors, gate driving voltages, and snubbers on self-sustained oscillations during both turn-on and turn-off transients are comprehensively and experimentally studied. It is shown that decreasing gate resistors, increasing positive driving voltage, decreasing negative driving voltage, and adding snubber circuits can suppress the self-sustained switching oscillations.</p
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