Electric machine

An electric machine comprising a stator, a rotor configured to rotate relative to the stator, the stator having a phase arrangement, wherein:

• the phase arrangement includes a first leg and a second leg connected in parallel at a first primary junction and a second primary junction;
• the first leg includes a first-leg first coil and a first-leg second coil connected in series through a first intermediate junction;
• the second leg includes a second-leg first coil and a second-leg second coil connected in series through a second intermediate junction, the first intermediate junction and the second intermediate junction being connected by a branch such that the phase arrangement is in the form of a bridge circuit;
• the phase arrangement is configured to conduct, through each leg, a motor current through the respective in series coils between the first primary junction and the second primary junction;
• the phase arrangement is configured to permit an alignment current to flow between the first primary junction and the second primary junction via the branch, the alignment current being conducted through an alignment current path which passes through one coil of each leg;
• the alignment current path has a positive electrical impedance provided by the coils of each leg;
• the phase arrangement includes a negative impedance converter configured to add a negative electrical impedance to the alignment current path by introducing additional electrical energy into the alignment current path;
• the electric machine is configured so that:
• the motor currents cause a torque to be applied to the rotor for rotation relative to the stator, and
• the alignment current causes a translational force to be applied to the rotor for maintaining alignment of the rotor with respect to the stator;
• the negative impedance converter is configured to control the additional electrical energy introduced to the alignment current path such that a magnitude of the negative electrical impedance added to the alignment current path is less than a magnitude of a total positive electrical impedance of the alignment current path;
• and
• the negative impedance converter is configured to control the additional electrical energy introduced to the alignment current path such that the magnitude of the negative electrical impedance added to the alignment current path is no greater than 95% of the magnitude of the total positive electrical impedance of the alignment current path.