The subject matter disclosed herein relates generally to semiconductor power conversion devices and, more specifically, to silicon carbide (SiC) power conversion devices.
Power conversion systems are widely used throughout modern electrical systems to convert electrical power from one form to another for consumption by a load. Many power electronics systems utilize various semiconductor devices and components, such as thyristors, diodes, and various types of transistors (e.g., metal-oxide-semiconductor field-effect transistor (MOSFETs), insulated gate bipolar transistors (IGBTs), and other suitable transistors), in this power conversion process. Larger power conversion system can include numerous power conversion devices (e.g., arranged into power modules) that cooperate to convert electrical power.
Gate resistance can dramatically affect the performance of SiC power conversion devices, such as SiC MOSFET and SiC IGBT power conversion devices. In general, such devices are designed to have low gate resistance to enable fast switching time and low switching losses. Additionally, when the device is switched off, the peak drain-source voltage of a SiC power conversion device can overshoot and temporarily exceed a rated or maximum voltage (Vmax) of the device, which can stress the power conversion device, as well as other components of a power module. While external resistors (e.g., standalone, surface-mounted or through-chip resistors) can be used to modify an external gate resistance of a power conversion device to reduce voltage overshoot and avoid or dampen oscillations, such external resistors generally add additional cost and complexity to the power modules, increase device switching losses, and consume precious limited space within the device packaging.
Additionally, unlike their Si counterparts, SiC power conversion devices generally exhibit an increase in transconductance as the temperature at the surface of the semiconductor die, also referred to as junction temperature (Tj), rises during device operation. This increased transconductance results in relatively faster switching transients (e.g. faster turn-on times) and more substantial changes in voltage and current per unit time when a SiC power conversion device is switching. As a result, a power conversion device that is operating at higher temperature than other power conversion devices tends to handle and conduct more current during switching transients, which can stress the power conversion devices as the module becomes dynamically imbalanced.