by Paul Kierstead, Cree, Durham, N.C., How2Power Today, Aug 30 2012
Focus:
Silicon carbide (SiC) material refinements and new power device availability are enabling a revolution in the power conversion market, particularly in motor drives. In many cases, SiC power MOSFETs and Schottky diodes can replace silicon components such as IGBTs and fast-recovery diodes, offering improvements in energy efficiency, faster switching speeds, smaller size, and potentially lower overall system cost and lower system operating costs. In this article, the author illustrates these benefits by analyzing the impact of SiC power devices on a standard variable-frequency motor drive, comparing the performance of SiC MOSFETs and Schottky rectifiers with the silicon devices they are meant to replace. This analysis covers all three power conversion sections within the motor drive including the dc-ac power inverter responsible for driving the motor at variable speeds and torques; the ac-dc rectifier section, which frequently includes regen circuitry; and the auxiliary power supply, which is responsible for powering the digital control and other functions. Topics discussed include the advantages of changing from a silicon-based three-level topology to a simpler SiC-based two-level topology, the option of moving switching frequencies beyond the audible range, and possible elimination of snubber components. The article also discusses issues that may affect adoption of SiC devices such as reliability and the range of currently available device ratings.
What you’ll learn:
Notes:
This article sparked a lively discussion in the “Motor Control & Motor Drive Professionals†group on LinkedIn. View that discussion
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