Method for controlling a synchronous double stator electric machine

A synchronous double stator electric machine being formed of at least one double stator unit comprising

• a rotor being rotatable around a shaft axis, the rotor comprising a first set of magnetic poles and a second set of magnetic poles,
• a first stator facing towards the first set of magnetic poles, wherein the first set of magnetic poles and the first stator form a first electric machine within the double stator electric machine, the first electric machine being controlled by a first frequency converter, a first load angle being formed between the magnetic flux of the first stator and the magnetic flux of the first set of magnetic poles,
• a second stator facing towards the second set of magnetic poles, wherein the second set of magnetic poles form a second electric machine within the double stator electric machine, the second electric machine being controlled by a second frequency converter, a second load angle being formed between the magnetic flux of the second stator and the magnetic flux of the second set of magnetic poles, wherein
• the first stator and the second stator has an equal number of slots,
• one of the two electric machines comprises a mechanical shift with a predetermined angle between the rotor and the stator causing the synchronous double stator electric machine to operate in a shifted topology compared to an un-shifted topology in which the rotor and the two stators are aligned, and
• at least the frequency converter controlling the mechanically shifted electric machine being configured to produce an electrical shift to the mechanically shifted electric machine in order to at least partly compensate for the mechanical shift in the mechanically shifted electric machine.

A computer program product comprising program instructions, which, when run on a computer, control a synchronous double stator electric machine being formed of at least one double stator unit comprising

• a rotor being rotatable around a shaft axis, the rotor comprising a first set of magnetic poles and a second set of magnetic poles,
• a first stator facing towards the first set of magnetic poles, wherein the first set of magnetic poles and the first stator form a first electric machine within the double stator electric machine, the first electric machine being controlled by a first frequency converter, a first load angle being formed between the magnetic flux of the first stator and the magnetic flux of the first set of magnetic poles,
• a second stator facing towards the second set of magnetic poles, wherein the second set of magnetic poles and the second stator form a second electric machine within the double stator electric machine, the second electric machine being controlled by a second frequency converter, a second load angle being formed between the magnetic flux of the second stator and the magnetic flux of the second set of magnetic poles, wherein
• the first stator and the second stator has an equal number of slots,
• one of the two electric machines comprises a mechanical shift with a predetermined angle between the rotor and the stator causing the synchronous double stator electric machine to operate in a shifted topology compared to an un-shifted topology in which the rotor and the two stators are aligned,
• wherein upon execution of the computer program by the computer there is produced an electrical shift to the control of at least the mechanically shifted electric machine with the respective frequency converter in order to at least partly compensate for the mechanical shift in the mechanically shifted electric machine.