High-temperature gate drive circuit for silicon-carbide JFETs

Abstract

An electrical and thermal optimization study is conducted for a high-temperature gate drive circuit, developed to drive custom-designed, 50 A, 600 V silicon-carbide (SiC) power modules consisting of multiple normally-off JFET dice (SemiSouth SJEC120R100) in parallel and rated at 175 °C device junction temperature. The gate drive and power modules are intended for use in a bi-directional DC-DC converter. The gate drive circuit is designed for operation in an enclosure in 120°C ambient air. Primary cooling of the gate drive is through the back of the circuit board to an aluminum plate, the base of which is cooled with engine coolant (water-ethylene glycol mixture) at an inlet temperature of 100°C. The power module consists of a single pole, with the close-coupled gate drive circuit providing independent and isolated drive for the two switches. The gate drive circuit is capable of operating the switches at PWM carrier frequencies up to 50 kHz, with duty cycles ranging from 0 to 98%.