Discharging a dc bus capacitor of an electrical converter system

A method of operating an electrical system comprising a direct current (DC) interface, an alternating current (AC) interface, a DC bus capacitor coupled electrically parallel to the DC interface, a first energy conversion module comprising a plurality of switching elements, a second energy conversion module comprising a plurality of switching elements, an isolation module coupled between the first energy conversion module and the second energy conversion module to provide galvanic isolation between the first energy conversion module and the second energy conversion module, and an inductive element coupled between the second energy conversion module and the AC interface, the method comprising:

• detecting a condition indicative of a need to discharge the DC bus capacitor;
• electrically shorting the AC interface;
• arranging the plurality of switching elements of the second energy conversion module into a discharge configuration to establish an electrical current path from a first terminal of the isolation module, through the inductive element, and to a second terminal of the isolation module;
• and
• modulating one or more of the plurality of switching elements of the first energy conversion module to alternately charge and discharge current in the inductive element, while maintaining the discharge configuration of the plurality of switching elements of the second energy conversion module.

A method of discharging a bus capacitor of a bidirectional matrix converter of a vehicle having a direct current (DC) energy source, the bidirectional matrix converter comprising a DC interface for the DC energy source, an alternating current (AC) interface for an AC energy source to charge the DC energy source via the bidirectional matrix converter, a first energy conversion module, a second energy conversion module, an isolation module coupled between the first energy conversion module and the second energy conversion module, and an inductive element coupled between the second energy conversion module and the AC interface, the method comprising:

• electrically shorting the AC interface after the AC energy source is disconnected from the AC interface;
• arranging a plurality of switching elements of the second energy conversion module into a discharge configuration to establish an electrical current path from a first terminal of the isolation module, through the inductive element, and to a second terminal of the isolation module;
• and
• modulating a plurality of switching elements of the first energy conversion module, while maintaining the discharge configuration of the second energy conversion module, to at least partially discharge the DC bus capacitor.