An electromechanical drive for a working machine

摘要

An electromechanical drive comprises an electrical machine (101 a), an electrical power converter (103) for converting voltage of an external electrical system to voltage suitable for the electrical machine, and a gearbox (111 a) for mechanically connecting the electrical machine to an actuator (112a) and capable of providing selectable transmission ratios between the electrical machine and the actuator. The electrical power converter comprises a controller for selecting one of the selectable transmission ratios at least partly on the basis of a) first data related to actual and/or desired torque-speed operating point of the actuator and b) second data related to functional properties of at least the electrical machine. Thus, the transmission ratio can be selected at least partly from the viewpoint of the electrical machine taking into account for example the most advantageous speed range and/or torque range of the electrical machine.