A Hybrid Current- and Voltage-Source Driver for Active Driving of Series-Connected SiC MOSFETs
Tobias Nieckula Ubostad, Daniel A. Philipps, Dimosthenis Peftitsis
Abstract
The series-connection of silicon carbide (SiC) metal-oxide-semiconductor field-effect transistors ( <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">mosfet</small> s) is an attractive way of increasing the blocking voltage capability of a switch. However, due to inherent transient and steady-state voltage imbalance issues, such a design imposes challenges, especially at elevated switching frequencies, where increased <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$dv/dt$</tex-math></inline-formula> is required. This article proposes a hybrid gate driver for series-connected Silicon Carbide (SiC) <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">mosfet</small> s, which consists of a turn- <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on</small> stage with a traditional voltage source gate driver (VSGD), and a turn- <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">off</small> sequence combining a <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Current Source Gate Driv</small> er (CSGD) and a Voltage Source Gate Driver (VSGD). The proposed hybrid gate driver can actively control the turn- <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">off</small> <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$dv/dt$</tex-math></inline-formula> and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$di/dt$</tex-math></inline-formula> of the switch by adjusting the amplitude of the gate current in the Current Source Gate Driver (CSGD) stage, as well as balance the voltages of the serialized switches by adjusting the timing delays in the driver. This adaptability enables switching loss control of the devices. The proposed driver has been experimentally validated for two series-connected SiC <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">mosfet</small> s. From experiments, it is shown that a voltage imbalance below 2% can be achieved at direct current (DC)-voltage of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">${\text {1.5}} \,{\text {k}}{\text {V}}$</tex-math></inline-formula> and that switching speeds can be adjusted between 20 and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">${\text {70}} \,{\text {k}} {\text {V}}$</tex-math></inline-formula> /µs, while the turn- <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">off</small> switching energy can be reduced by up to 41%.