Drive apparatus and method for improving the efficiency

The arrangement has at least two electrical machines (E1,E2) coupled together via an intermediate gearbox (20) coupled to a driven shaft (21) and a controller for variable control of the electrical machines depending on a revolution rate demand and/or a torque demand at the driven shaft. An idler (22) is arranged between at least one of the electrical machines and the intermediate gearbox. An independent claim is also included for the following: (a) a method of converting between electrical and mechanical energy, especially for vehicle drive.