Work machine and method for controlling work machine

A work machine comprising:

• an engine to move the work machine;
• a motor-generator to move the work machine and to generate electric power;
• an actual rotational speed detector to detect an actual rotational speed of the engine;
• and
• circuitry configured to control the motor-generator to move the work machine when the actual rotational speed is lower than or equal to a first rotational speed threshold and to generate the electric power when the actual rotational speed exceeds a second rotational speed threshold which is larger than or equal to the first rotational speed threshold.

A work machine comprising:

• an engine to move the work machine;
• a motor-generator to move the work machine and to generate electric power;
• a target rotational speed setting interface via which a target rotational speed of the engine is set;
• and
• an actual rotational speed detector to detect an actual rotational speed of the engine;
• and
• circuitry configured to control the motor-generator to move the work machine when a difference between the actual rotational speed and the target rotational speed is higher than or equal to a difference threshold, and to generate the electric power when the difference between the actual rotational speed and the target rotational speed is lower than the difference threshold.

A method for controlling a work machine, comprising:

• controlling an engine to move the work machine;
• detecting a charge level of electric power stored in a battery;
• detecting a temperature of the battery;
• and
• controlling a motor-generator in accordance with the charge level selectively to move the work machine with electric power supplied from the battery or to generate electric power to charge the battery by driving the motor-generator by the engine when the temperature of the battery is within a temperature range.

A method for controlling a work machine, comprising:

• controlling an engine to move the work machine;
• detecting an actual rotational speed of the engine;
• and
• controlling a motor-generator to move the work machine when the actual rotational speed is lower than or equal to a first rotational speed threshold and to generate the electric power when the actual rotational speed exceeds a second rotational speed threshold which is larger than or equal to the first rotational speed threshold.

A method for controlling a work machine, comprising:

• controlling an engine to move the work machine;
• setting a target rotational speed of the engine;
• detecting an actual rotational speed of the engine;
• and
• controlling a motor-generator to move the work machine when a difference between the actual rotational speed and the target rotational speed is higher than or equal to a difference threshold and to generate the electric power when the difference between the actual rotational speed and the target rotational speed is lower than the difference threshold.