Piecewise temperature compensation for power switching devices

Abstract

A power switching circuit provides temperature compensation for an insulated gate power switching device. A timing circuit determines a switch timing signal comprising desired on and off switching times of the switching device. A temperature monitor quantifies a device temperature. A gate drive profile generator generates a switching device drive signal according to the switch timing signal and having a dv / dt phase and a di / dt phase. The drive signal has a profile during the di / dt phase that is adjusted in response to the device temperature, and the drive signal has a profile during the dv / dt phase that is not adjusted in response to the device temperature.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]Not Applicable.STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH[0002]Not Applicable.BACKGROUND OF THE INVENTION[0003]The present invention relates in general to controlling switching transients for power switching transistors, and, more specifically, to temperature-compensated gate drive signals for power converters of a type used in electrified vehicles.[0004]Electrified vehicles, such as hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), and battery electric vehicles (BEVs), use inverter-driven electric machines to provide traction torque. A typical electric drive system includes a DC power source (such as a battery pack or a fuel cell) coupled by contactor switches to a variable voltage converter (VVC) to regulate a main bus voltage across a main DC link capacitor. An inverter is connected between the main buses for the DC link and a traction motor in order to convert the DC power to an AC power that is coupled ...

AI Technical Summary

Benefits of technology

The present invention provides a power switching circuit with an insulated gate power switching device that separately controls the dv / dt and di / dt portions to ensure optimal performance at different temperatures. A timing circuit determines the desired on and off switching times, a temperature monitor quantifies the device temperature, and a generator generates a driving signal with adjusted profiles during the di / dt and dv / dt phases. The generator includes a controlled current source. The technical effects of the invention include improved performance and reliability of the power switching circuit at different temperatures.

Problems solved by technology

The optimal switching speed of a power semiconductor transistor device such as an IGBT is a tradeoff between high stresses which could destroy the device at very fast switching speeds and reduced efficiency and increase power losses at slower switching speeds.

Generally, as temperature increases the switching speed decreases, so that switching losses increases; as temperature decreases, the voltage and current stress increases, so that the reliability decreases.

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