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Accelerated testing of module-level power electronics for long-term reliability

IEEE Journal of Photovoltaics

Flicker, Jack D.; Tamizhmani, Govindasamy; Moorthy, Mathan K.; Thiagarajan, Ramanathan; Ayyanar, Raja

This work has applied a suite of long-term-reliability accelerated tests to a variety of module-level power electronics (MLPE) devices (such as microinverters and optimizers) from five different manufacturers. This dataset is one of the first (only the paper by Parker et al. entitled 'Dominant factors affecting reliability of alternating current photovoltaic modules,' in Proc. 42nd IEEE Photovoltaic Spec. Conf. , 2015, is reported for reliability testing in the literature), as well as the largest, experimental sets in public literature, both in the sample size (five manufacturers including both dc/dc and dc/ac units and 20 units for each test) and the number of experiments (six different experimental test conditions) for MLPE devices. The accelerated stress tests (thermal cycling test per IEC 61215 profile, damp heat test per IEC 61215 profile, and static temperature tests at 100 and 125 °C) were performed under powered and unpowered conditions. The first independent long-term experimental data regarding damp heat and grid transient testing, as well as the longest term (>9 month) testing of MLPE units reported in the literature for thermal cycling and high-temperature operating life, are included in these experiments. Additionally, this work is the first to show in situ power measurements, as well as periodic efficiency measurements over a series of experimental tests, demonstrating whether certain tests result in long-term degradation or immediate catastrophic failures. The result of this testing highlights the performance of MLPE units under the application of several accelerated environmental stressors.

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TYPE Journal Article YEAR 2017
DOIOSTIScopus

Module-level paralleling of vertical GaN PiN diodes

WiPDA 2016 - 4th IEEE Workshop on Wide Bandgap Power Devices and Applications

Flicker, Jack D.; Brocato, Robert W.; Delhotal, Jarod J.; Neely, Jason C.; Sumner, Bjorn; Dickerson, Jeramy; Kaplar, Robert

The effects of paralleling low-current vertical Gallium Nitride (v-GaN) diodes in a custom power module are reported. Four paralleled v-GaN diodes were demonstrated to operate in a buck converter at 1.3 Apeak (792 mArms) at 240 V and 15 kHz switching frequency. Additionally, high-fidelity SPICE simulations demonstrate the effects of device parameter variation on power sharing in a power module. The device parameters studied were found to have a sub-linear relationship with power sharing, indicating a relaxed need to bin parts for paralleling. This result is very encouraging for power electronics based on low-current v-GaN and demonstrates its potential for use in high-power systems.

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TYPE Conference Poster YEAR 2016
DOIOSTIScopus

Identification of the primary compensating defect level responsible for determining blocking voltage of vertical GaN power diodes

Applied Physics Letters

King, Michael P.; Kaplar, Robert; Dickerson, Jeramy; Lee, Stephen R.; Allerman, A.A.; Crawford, Mary H.; Marinella, Matthew; Flicker, Jack D.; Fleming, R.M.; Kizilyalli, I.C.; Aktas, O.; Armstrong, Andrew A.

Electrical performance and characterization of deep levels in vertical GaN P-i-N diodes grown on low threading dislocation density (∼104 - 106cm-2) bulk GaN substrates are investigated. The lightly doped n drift region of these devices is observed to be highly compensated by several prominent deep levels detected using deep level optical spectroscopy at Ec-2.13, 2.92, and 3.2 eV. A combination of steady-state photocapacitance and lighted capacitance-voltage profiling indicates the concentrations of these deep levels to be Nt = 3 × 1012, 2 × 1015, and 5 × 1014cm-3, respectively. The Ec-2.92 eV level is observed to be the primary compensating defect in as-grown n-type metal-organic chemical vapor deposition GaN, indicating this level acts as a limiting factor for achieving controllably low doping. The device blocking voltage should increase if compensating defects reduce the free carrier concentration of the n drift region. Understanding the incorporation of as-grown and native defects in thick n-GaN is essential for enabling large VBD in the next-generation wide-bandgap power semiconductor devices. Thus, controlling the as-grown defects induced by epitaxial growth conditions is critical to achieve blocking voltage capability above 5 kV.

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TYPE Journal Article YEAR 2016
DOIOSTIScopus
Results 126–150 of 193
Results 126–150 of 193