Abstract: A hybrid propulsion unit for an aircraft with multi-rotor rotary wings includes an electrical generator driven by an internal combustion engine, a rectifier configured to convert an AC current sent by the electrical generator into DC current, a DC-AC converter, an electrical network connecting the rectifier to the converter and including a high-voltage DC current bus, electric motors powered by propeller converters coupled to the electric motors, electrical energy storage connected to the electrical network, the electrical storage including at least one primary storage element and at least one secondary storage element.