Wound-rotor electric machine

A system for converting energy for a vehicle, the system comprising:

• a doubly-fed induction machine including:
• a rotor having a plurality of rotor windings, wherein the plurality of rotor windings further includes a first three-phase rotor winding having a first rotor winding coil, a second rotor winding coil, and a third rotor winding coil and a second three-phase rotor winding having a fourth rotor winding coil, a fifth rotor winding coil, and a sixth rotor winding coil;
• and
• a stator having a plurality of stator windings;
• a power conversion unit in electrical communication with the plurality of rotor windings, the power conversion unit further comprising:
• a first inverter having three outputs, wherein each output of the first inverter is in electrical communication with one of the first, second, or third rotor winding coils;
• and
• a second inverter having three outputs, wherein each output of the second inverter is in electrical communication with one of the fourth, fifth, or sixth rotor winding coils;
• a relay unit in electrical communication with the plurality of stator windings;
• and
• a controller in electrical communication with the power conversion unit and the relay unit, wherein the controller is programmed to:
• determine a rotational velocity of the rotor;
• adjust an operation of the doubly-fed induction machine using the power conversion unit and the relay unit based on the rotational velocity of the rotor, wherein to adjust the operation of the doubly-fed induction machine, the controller is further programmed to:
• configure the doubly-fed induction machine to have four effective poles using the power conversion unit by:
• configuring the first inverter to excite the first rotor winding coil with a first sinusoidal current, excite the second rotor winding coil with a second sinusoidal current, wherein the second sinusoidal current lags the first sinusoidal current by 240 degrees, excite the third rotor winding coil with a third sinusoidal current, wherein the third sinusoidal current lags the first sinusoidal current by 120 degrees;
• and
• configuring the second inverter to excite the fourth rotor winding coil with a fourth sinusoidal current, wherein the fourth sinusoidal current is 180 degrees out of phase with the first sinusoidal current, excite the fifth rotor winding coil with a fifth sinusoidal current, wherein the fifth sinusoidal current is 180 degrees out of phase with the second sinusoidal current, and excite the sixth rotor winding coil with a sixth sinusoidal current, wherein the sixth sinusoidal current is 180 degrees out of phase with the third sinusoidal current.

An electric machine comprising:

• a stator having a hollow cylindrical shape, the stator including:
• a plurality of stator slots disposed at a uniform pitch along a circumference of the stator;
• a first, second, third, fourth, fifth, and sixth stator coil, wherein each stator coil has a first stator coil loop electrically connected in series to a second stator coil loop;
• and
• wherein for each of the first, second, third, fourth, fifth, and sixth stator coil:
• the first stator coil loop is disposed in a first pair of stator slots, wherein a center of the first stator coil loop is substantially coincident with the circumference of the stator, and wherein a second pair of stator slots is disposed between the first pair of stator slots;
• and
• the second stator coil loop is disposed in a third pair of stator slots, wherein a center of the second stator coil loop is substantially coincident with the circumference of the stator, wherein a fourth pair of stator slots is disposed between the third pair of stator slots, and wherein the third pair of stator slots are diametrically opposed to the first pair of stator slots such that the second stator coil loop is diametrically opposed to the first stator coil loop;
• and
• a rotor disposed rotatably inside the stator along a central axis of the stator, the rotor including:
• a plurality of rotor slots disposed at a uniform pitch along a circumference of the rotor;
• a first, second, third, fourth, fifth, and sixth rotor coil, wherein each rotor coil has a first rotor coil loop electrically connected in series to a second rotor coil loop;
• and
• wherein for each of the first, second, third, fourth, fifth, and sixth rotor coil:
• the first rotor coil loop is disposed in a first pair of rotor slots, wherein a center of the first rotor coil loop is substantially coincident with the circumference of the rotor, and wherein a second pair of rotor slots is disposed between the first pair of rotor slots;
• and
• the second rotor coil loop is disposed in a third pair of rotor slots, wherein a center of the second rotor coil loop is substantially coincident with the circumference of the rotor, wherein a fourth pair of rotor slots is disposed between the third pair of rotor slots, and wherein the third pair of rotor slots are diametrically opposed to the first pair of rotor slots such that the second rotor coil loop is diametrically opposed to the first rotor coil loop.