Propulsion system (20, 30; 20', 30') for a non-rotary-wing aircraft (1; 2; 3; 4) comprising: - an alternating-current generator (24, 34), - at least one wingtip propulsion unit (22, 32) comprising an alternating-current motor (221, 321), having a direction of rotation that opposes the formation of wingtip vortices, - at least one lift-increase propulsion unit (23a, 23b, 23c, 23d, 33a, 33b, 33c, 33d), comprising an alternating-current motor, - a first AC power supply circuit (25, 35), that electrically connects the generator (24, 34) to the wingtip propulsion unit (22, 32), and - a second AC power supply circuit (26, 36), that electrically connects the generator (24, 34) to the lift-increase propulsion unit (23a, 23b, 23c, 23d, 33a, 33b, 33c, 33d), - the second power supply circuit (26, 36) comprising: ∘ an intermediate DC distribution stage (260, 360), ∘ one or more electric batteries (262, 362) connected to said intermediate DC distribution stage (260, 360), ∘ an AC/DC converter (261, 361), that electrically connects the generator (24, 34) to said intermediate DC distribution stage (260, 360), and ∘ a DC/AC converter (263a, 263b, 263c, 263d, 363a, 363b, 363c, 363d), that electrically connects said intermediate stage (260, 360) to the lift-increase propulsion unit (23a, 23b, 23c, 23d, 33a, 33b, 33c, 33d), - the first power supply circuit (25, 35) being configured to deliver (22, 32) an AC current produced by the generator (24, 34), to the wingtip propulsion unit, without intermediate conversion of this alternating current into direct current. - an alternating-current generator (24, 34), - at least one wingtip propulsion unit (22, 32) comprising an alternating-current motor (221, 321), having a direction of rotation that opposes the formation of wingtip vortices, - at least one lift-increase propulsion unit (23a, 23b, 23c, 23d, 33a, 33b, 33c, 33d), comprising an alternating-current motor, - a first AC power supply circuit (25, 35), that electrically connects the generator (24, 34) to the wingtip propulsion unit (22, 32), and - a second AC power supply circuit (26, 36), that electrically connects the generator (24, 34) to the lift-increase propulsion unit (23a, 23b, 23c, 23d, 33a, 33b, 33c, 33d), - the second power supply circuit (26, 36) comprising: ∘ an intermediate DC distribution stage (260, 360), ∘ one or more electric batteries (262, 362) connected to said intermediate DC distribution stage (260, 360), ∘ an AC/DC converter (261, 361), that electrically connects the generator (24, 34) to said intermediate DC distribution stage (260, 360), and ∘ a DC/AC converter (263a, 263b, 263c, 263d, 363a, 363b, 363c, 363d), that electrically connects said intermediate stage (260, 360) to the lift-increase propulsion unit (23a, 23b, 23c, 23d, 33a, 33b, 33c, 33d), ∘ an intermediate DC distribution stage (260, 360), ∘ one or more electric batteries (262, 362) connected to said intermediate DC distribution stage (260, 360), ∘ an AC/DC converter (261, 361), that electrically connects the generator (24, 34) to said intermediate DC distribution stage (260, 360), and ∘ a DC/AC converter (263a, 263b, 263c, 263d, 363a, 363b, 363c, 363d), that electrically connects said intermediate stage (260, 360) to the lift-increase propulsion unit (23a, 23b, 23c, 23d, 33a, 33b, 33c, 33d), - the first power supply circuit (25, 35) being configured to deliver (22, 32) an AC current produced by the generator (24, 34), to the wingtip propulsion unit, without intermediate conversion of this alternating current into direct current.