Electromechanical drive for a working machine

A method for controlling an electromechanical drive that includes an electrical machine, an electrical power converter for converting voltage of an external electrical system to voltage suitable for the electrical machine, and a gearbox having a first shaft connected to the electrical machine and a second shaft for driving an actuator, the gearbox being capable of providing selectable transmission ratios each being a ratio of a rotational speed of the first shaft to a rotational speed of the second shaft, the method comprising:

• selecting, by the electrical power converter, one of the selectable transmission ratios on the basis of a) first data related to a torque-speed operating point of the second shaft when driving the actuator and b) second data related to functional properties of at least the electrical machine;
• and
• delivering, from the electrical power converter to the gearbox, a control signal so as to set the gearbox to operate at the selected one of the selectable transmission ratios.

A non-volatile computer readable medium encoded with a computer program for controlling an electromechanical drive that includes an electrical machine, an electrical power converter for converting voltage of an external electrical system to voltage suitable for the electrical machine, and a gearbox having a first shaft connected to the electrical machine and a second shaft for driving an actuator, the gearbox being capable of providing selectable transmission ratios each being a ratio of a rotational speed of the first shaft to a rotational speed of the second shaft, the computer program comprising computer executable instructions for controlling a programmable processing system of the electrical power converter to:

• select one of the selectable transmission ratios on the basis of a) first data related to a torque-speed operating point of the second shaft when driving the actuator and b) second data related to functional properties of at least the electrical machine;
• and
• transmit, from the electrical power converter to the gearbox, a control signal so as to set the gearbox to operate at the selected one of the selectable transmission ratios.