Propulsion system for a vehicle

A vehicle comprising a drive system wherein the drive system comprises:

• an output shaft in a combustion engine;
• an input shaft of a gearbox;
• an electrical machine comprising a stator and a rotor;
• a planetary gear comprising three components in the form of a sun wheel, a ring gear and a planetary wheel carrier, wherein the output shaft of the combustion engine is connected with a first of said components in the planetary gear, so that a rotation of such shaft leads to a rotation of such first of said components, wherein the input shaft of the gearbox is connected with a second of said components of the planetary gear, so that a rotation of such shaft leads to a rotation of such second of said components, and wherein the rotor of the electrical machine is connected with a third of said components in the planetary gear, so that a rotation of the rotor leads to a rotation of such third of said components;
• a first locking means, which may be moved between a locked position in which two of said components are locked together so that the three components rotate with the same rotational speed, and a release position in which the components are allowed to rotate at different rotational speeds;
• a second locking means, which may be moved between a locked position in which the combustion engine's output shaft is locked to said first of said components, and a release position, in which the output shaft of the combustion engine is disconnected from said first of said components, and is allowed to rotate independently;
• and
• at least one control device, adapted to control fuel supply to the combustion engine and to control exchange of electrical energy between the electrical machine and storage means for electric energy,
• wherein the control device is adapted to control said first and second locking means to be moved between said locked position and release position and, in order to lock, to control the combustion engine and/or the electrical machine to achieve the same rotational speed in the parts to be locked together by the respective first and second locking means, and, subsequently, to control the locking means to be moved to a locked position and, in order to release, to control the combustion engine and/or the first electrical machine to achieve a torque balance between the parts to be released from each other, and, subsequently, to control the first and second locking means to be moved to a release position, and
• wherein the control device is adapted to control, when the vehicle is driven with the combustion engine running, and with the second locking means in a locked position at braking of the vehicle:
• the electrical machine to apply a braking torque to the input shaft of the gearbox throughout the braking of the vehicle;
• the combustion engine and the electrical machine to a synchronous rotational speed of the input shaft of the gearbox, the electrical machine's rotor (9b) and the combustion engine's output shaft if the first locking means is in a release position, and to move the first locking means to a locked position;
• the combustion engine towards a zero torque between the combustion engine's output shaft and said first of said components, when a certain value of a vehicle speed is not met;
• the second locking means to be moved to the release position;
• and
• the combustion engine towards and to idling speed.