Rapid transistor switching in a converter with limited capacitance

An electrical propulsion unit (EPU) for an aircraft, the EPU comprising:

• an electric motor;
• and
• an AC-DC power electronics converter configured as an inverter and arranged to supply current to a winding of the electric motor,
• wherein the AC-DC power electronics converter comprises:
• a converter commutation cell comprising a power circuit and a gate driver circuit, the power circuit comprising at least one power semiconductor switching element and at least one capacitor,
• wherein each power semiconductor switching element of the at least one power semiconductor switching element is comprised in a power semiconductor prepackage,
• wherein the power semiconductor prepackage comprises one or more power semiconductor switching elements embedded in a solid insulating material, each power semiconductor switching element of the one or more power semiconductor switching elements having at least three terminals including a gate terminal,
• wherein the gate driver circuit is electrically connected to each power semiconductor switching element of the at least one power semiconductor switching element,
• wherein the gate driver circuit is configured to provide switching signals to the gate terminal of each power semiconductor switching element of the at least one power semiconductor switching element, and
• wherein a peak rated power output of the AC-DC power electronics converter is greater than 25 kW and a value of a converter parameter γ is less than or equal to 150 fFs/W, where the converter parameter γ is a total rated capacitance of the at least one capacitor of the power circuit divided by a product of the peak rated power output of the AC-DC power electronics converter and a maximum switching frequency of the switching signals.

A gas turbine engine comprising:

• a spool;
• an electrical machine having a rotor mechanically coupled to the spool;
• and
• an AC-DC power electronics converter configured to supply current to or receive current from a winding of the electric machine,
• wherein the AC-DC power electronics converter comprises:
• a converter commutation cell comprising a power circuit and a gate driver circuit, the power circuit comprising at least one power semiconductor switching element and at least one capacitor,
• wherein each power semiconductor switching element of the at least one power semiconductor switching element is comprised in a power semiconductor prepackage,
• wherein the power semiconductor prepackage comprises one or more power semiconductor switching elements embedded in a solid insulating material, each power semiconductor switching element of the one or more power semiconductor switching elements having at least three terminals including a gate terminal,
• wherein the gate driver circuit is electrically connected to each power semiconductor switching element of the at least one power semiconductor switching element,
• wherein the gate driver circuit is configured to provide switching signals to the gate terminal of each power semiconductor switching element of the at least one power semiconductor switching element, and
• wherein a peak rated power output of the AC-DC power electronics converter is greater than 25 kW and a value of a converter parameter γ is less than or equal to 150 fFs/W, where the converter parameter γ is a total rated capacitance of the at least one capacitor of the power circuit divided by a product of the peak rated power output of the AC-DC power electronics converter and a maximum switching frequency of the switching signals.