Electrical architecture for a rotary wing aircraft with a hybrid power plant

A method of operating a rotary wing aircraft, the aircraft having:

• a main on-board electricity network;
• a power plant having at least one rotor for being driven in rotation, and at least one transmission for driving said rotor in rotation;
• the power plant being a hybrid power plant associating at least one main combustion engine with at least one hybrid drive auxiliary electrical machine;
• the main engine and the auxiliary electrical machine being mechanically coupled to the transmission;
• the auxiliary electrical machine being placed within the hybrid power plant to constitute in turn a member for mechanically driving the transmission or a member for generating electricity under the effect of being driven mechanically by said transmission;
• the on-board electricity network possessing at least one main electrical bus at a main nominal voltage;
• the main electrical bus having connected thereto at least one main device for delivering electric charge with at least one main storage battery, and a main electrical machine acting as a starter that is reversibly operable as a generator, said main electrical machine forming a starter being mechanically connected to said engine, the hybrid power plant including at least one hybrid drive system with at least one auxiliary electricity network for providing hybrid drive purposes, the auxiliary electricity network possessing a dedicated auxiliary electrical bus at an auxiliary nominal voltage, the auxiliary electrical machine being connected to the auxiliary electrical bus at the auxiliary nominal voltage;
• the main electrical bus and the hybrid drive auxiliary electrical bus being connected together via a selective adaptation interface in such a manner that the main on-board electricity network and the auxiliary electricity network are electrically distinct from one another, the selective adaption interface being configured to enable electrical energy to be exchanged selectively between the main and auxiliary electricity networks,
• the method comprising:
• in a stage of starting the engine, initiating said starting from the starter powered via the auxiliary electricity network, with this applying with an engine;
• in a flight stage, driving the transmission via said engine in a mode of self-sustained operation;
• and
• in a flight stage and in order to deliver extra mechanical energy occasionally to the transmission, driving the transmission from the auxiliary electrical machine operating as a motor and powered by at least one device for delivering electric charge of the main electricity network, in addition to the drive delivered to the transmission by the engine, for the purpose of performing specific flight controls and/or of taking the place of the drive delivered to the transmission by said engine in the event of the engine failing.