Cree Inc.

About: Cree Inc. is a company organization based out in Shenzhen, China. It is known for research contribution in the topics: Layer (electronics) & Silicon carbide. The organization has 1014 authors who have published 2436 publications receiving 64884 citations.

Performance comparison of 1200V Silicon and SiC devices for UPS application

Abstract: In this paper, a comparative study of 1200V Silicon IGBTs with Silicon Carbide (SiC) MOSFETs is presented for a 6kVA single-phase 230V online Uninterruptible Power Supply (UPS) system. The UPS is first tested with the 1200V silicon IGBT/Diode devices (2 parallel 34A IGBT/diode) and then the inverter devices are replaced by next generation SiC 1200V MOSFET/Diode devices (2 parallel 20A MOSFET/10A Diode co-packs). The UPS efficiency is compared with two different sets of devices, at different loading and gate driving conditions. SiC MOSFETs significantly improve the efficiency of the UPS at light load conditions. The experimental results are presented at 20kHz switching frequency.

Lamp with remote LED light source and heat dissipating elements

Abstract: LED based lamps and bulbs are disclosed that comprise an elevating element to arrange. LEDs above the lamp or bulb base. The elevating element can at least partially comprise a thermally conductive material. A heat sink structure is included, with the elevating element thermally coupled to the heat sink structure. A diffuser can be arranged in relation to the LEDs so at least some light from the LEDs passes through the diffuser and is dispersed into the desired emission pattern. Some lamps and bulbs utilize a heat pipe for the elevating elements, with heat from the LEDs conducting through the heat pipe to the heat sink structure where it can dissipate in the ambient. The LED lamps can include other features to aid in thermal management and to produce the desired emission pattern, such as internal optically transmissive and thermally conductive materials, and heat sinks with different heat fin arrangements.

Optical communication for solid-state light sources

Abstract: The disclosure relates to a lighting fixture, which includes an array of solid-state light sources that are configured to generate light for general illumination lighting purposes and control circuitry. A drive signal is used to drive solid-state light sources. The control circuitry is configured to use a control output to control the drive signal to at least one of the solid-state light sources. The control output is configured to control the drive signal to 1) set at least one characteristic of the light generated by the array of the solid-state light sources, and 2) modulate the light with data for transmission. The light is modulated such that any change in the at least one characteristic based on the light being modulated is anthropically imperceptible. The characteristic of the light generated by the array of solid-state light sources may include the intensity, color, color temperature and the like.

Comparison of 4.5 kV SiC JBS and Si PiN diodes for 4.5 kV Si IGBT anti-parallel diode applications

Abstract: A new 60 A, 4.5 kV SiC JBS diode is presented, and its performance is compared to a Si PiN diode used as the antiparallel diode for 4.5 kV Si IGBTs. The I-V, C-V, reverse recovery, and reverse leakage characteristics of both diode types are measured. The devices are also characterized as the anti-parallel diode for a 4.5 kV Si IGBT using a recently developed high-voltage, double-pulse switching test system. The results indicate that SiC JBS diodes reduce IGBT turn-on switching loses by about a factor of three in practical applications. Furthermore, the peak IGBT current at turn-on is typically reduced by a factor of six, resulting in substantially lower IGBT stress. Circuit simulator models for the 4.5 kV SiC JBS and Si PiN diodes are also developed and compared with measurements.

Reduction of subsurface damage in the production of bulk SiC crystals

Abstract: The invention is an improvement in a method of producing a high quality bulk single crystal of silicon carbide in a seeded sublimation system. The improvement includes etching the front face on each of a first and second SiC seed to a depth of greater than about 20 μm while protecting the opposite or back face on each of the first and second SiC seeds. Protection of the front faces occurs by placing the faces sufficiently close to one another to shield the back faces from being etched during etching of the respective unprotected front faces. Separation of the first and second SiC seeds occurs after the etching of the front faces is complete.