Inverter cell arrangement for brushless electrical machine
An electrical machine includes a stator core and a plurality of windings subdivided into a plurality of multiphase motor cells, each multiphase motor cell having M windings associated therewith, and having a phase shift relative to other multiphase motor cells. The electrical machine may include N inverter cells coupled in series; wherein each inverter cell is a multiphase inverter; and wherein the voltage magnitude supplied to a corresponding multiphase motor cell is V DC /N. The electrical machine may include a sensor system in communication with the plurality of inverter cells and operative to commutate each inverter cell in a sequence.
1. A brushless electrical machine powered by a DC voltage, V DC , comprising:
a stator core having a plurality of teeth;
a plurality of windings, each winding disposed about at least one stator tooth, wherein the plurality of windings are subdivided into a plurality of multiphase motor cells, each multiphase motor cell having a number, M, of windings associated therewith; and each multiphase motor cell having a phase shift relative to other multiphase motor cells;
a plurality of discrete square wave inverter cells, wherein a number, N, of the discrete square wave inverter cells are coupled in series; wherein each square wave inverter cell is electrically coupled to a multiphase motor cell; wherein each square wave inverter cell is a multiphase inverter; and wherein the voltage magnitude supplied from each square wave inverter cell to the corresponding multiphase motor cell is V DC /N; and
a sensor system comprising a sensor including an output coupled to a switching device of one of the discrete square wave inverter cells, the sensor being structured to sense a rotor position and turn on or off the switching device without an intervening controller.
2. The electrical machine of claim 1 , M=3 for each of the motor cells.
3. The electrical machine of claim 1 , wherein the windings are fractional slot windings.
4. The electrical machine of claim 3 , wherein the windings are fractional slot concentrated windings.
5. The electrical machine of claim 1 , wherein the electrical machine has at least six (6) phases.
6. The electrical machine of claim 1 , wherein the plurality of discrete square wave inverter cells supply power to pairs of the multiphase motor cells simultaneously.
7. The electrical machine of claim 6 , wherein the poles are permanent magnet poles.
8. The electrical machine of claim 1 , wherein each discrete square wave inverter cell is operative to supply power to more than one winding.
9. The electrical machine of claim 1 , further comprising a rotor, wherein the sensor system includes a plurality of Hall effect sensors operative to sense a rotor position; and
wherein each Hall effect sensor is operative to provide a switch signal to turn on or off a corresponding one of the discrete square wave inverter cells.
10. A brushless electrical machine powered by a DC voltage, the DC voltage being V DC , comprising:
a rotor having a plurality of poles;
a stator having a plurality of windings constructed for magnetic communication with the poles; wherein the plurality of windings are subdivided into a plurality of multiphase motor cells, each multiphase motor cell being formed of a plurality of windings; and each multiphase motor cell being phase shifted relative to another multiphase motor cell;
a voltage converter formed of a plurality of discrete brushless DC inverter cells, wherein at least a number, N, of the discrete brushless DC inverter cells are coupled to each other in a series arrangement, wherein each brushless DC inverter cell is operative to supply power to a multiphase motor cell; and wherein the voltage magnitude supplied to each multiphase motor cell is V DC /N; and
a sensor system including a sensor coupled to a switching device of the plurality of brushless DC inverter cells, the sensor being structured to sense a rotor position, generate a control signal based on the sensed rotor position, and output the control signal directly from the sensor to the switching device.
11. The electrical machine of claim 10 , wherein each multiphase motor cell is a 3-phase motor cell.
12. The electrical machine of claim 10 , the stator including a plurality of slots, each slot being disposed between adjacent windings, wherein the windings are fractional slot windings.
13. The electrical machine of claim 12 , wherein the windings are fractional slot concentrated windings.
14. The electrical machine of claim 10 , wherein the electrical machine has at least six (6) phases.
15. The electrical machine of claim 10 , wherein the voltage converter is constructed to supply power to pairs of the multiphase motor cells simultaneously.
16. The electrical machine of claim 10 , wherein the poles are permanent magnet poles.
17. The electrical machine of claim 10 , wherein each brushless DC inverter cell is operative to supply square wave power signals to the multiphase motor cell.
18. The electrical machine of claim 10 , wherein the sensor system includes a plurality of Hall effect sensors operative to determine rotor rotational location; and wherein each Hall effect sensor is in electrical communication with a corresponding one of the discrete brushless DC inverter cells.