Centrifugal pump with integrated axial flux permanent magnet motor
A pump system comprises a fluid housing, a permanent magnet rotor, and an electric stator. The fluid housing has an axis, an axial inlet, and a radially outer outlet. The permanent magnet rotor is disposed on the axis, within the fluid housing, and has a plurality of perimetrically distributed fins that extend at least partly radially outward. The electric stator is disposed on the axis and within the fluid housing, and is situated adjacent the impeller fins of the permanent magnet rotor, separated from the impeller fins by an axial gap.
1. A pump system comprising:
a fluid housing with an axis, an axial inlet, and a radially outer outlet;
a permanent magnet rotor disposed on the axis, within the fluid housing, the permanent magnet rotor comprising:
a rotor backing disk;
a plurality of truncated arcuate permanent magnet sections affixed to the backing plate, each of the plurality of permanent magnet sections circumferentially spaced apart from an adjacent permanent magnet section by a gap; and
a ferromagnetic pole shoe impeller fin abutting each of the plurality of permanent magnet sections; and
an electric stator disposed on the axis, within the fluid housing, adjacent the axial inlet and the pole shoe impeller fins of the permanent magnet rotor, and separated from the pole shoe impeller fins by an axial gap, such that each pole shoe impeller fin extends axially from each of the plurality of permanent magnet sections toward the electric stator.
2. The pump system of claim 1 , wherein the rotor backing disk comprises a ferromagnetic material.
3. The pump system of claim 2 , wherein the ferromagnetic rotor backing disk is formed of steel.
4. The pump system of claim 1 , wherein the plurality of permanent magnet sections are formed of a material selected from the group consisting of SmCo and NdFeB.
5. The pump system of claim 1 , wherein the plurality of permanent magnet sections are disposed axially between the rotor backing disk and the impeller fins.
6. The pump system of claim 1 , wherein the electric stator is surrounded by a fluid-sealing laminate.
7. The pump system of claim 1 , wherein the electric stator includes at least one axially-oriented stator passage disposed to allow passage of fluid from the axial inlet to the axial gap.
8. The pump system of claim 1 , wherein the electric stator comprises a plurality of perimetrically distributed poles, each having a ferromagnetic core surrounded by a plurality of windings.
9. The pump system of claim 7 , wherein the at least one axially-oriented stator passage is disposed through at least one ferromagnetic core.
10. The pump system of claim 9 , wherein the at least one ferromagnetic core containing the at least one axially-oriented stator passage is evenly perimetrically distributed about the axis with respect to the plurality of ferromagnetic cores.
11. The pump system of claim 7 , wherein:
the electric stator has a number m of phases;
the plurality of impeller fins includes an even number B of impeller fins; and
the plurality of perimetrically distributed poles includes a number N c of poles equal to a number of stator coils, such that N c is an integer multiple of m times the greatest common divisor of N c and B.
12. A method of pumping fluid, the method comprising:
energizing field poles of the stator of claim 1 situated in an axial fluid path of a centrifugal pump housing with alternating current; and
driving the permanent magnet rotor via axial flux impingement from the energized stator on the at least partially radially extending pole shoe impeller fins, such that the fluid is:
drawn axially through at least one aperture in the stator; and
forced centrifugally outward and in a radial flow direction by the fluid impeller fins.
13. The method of claim 12 , wherein the at least one aperture is a plurality of apertures in the stator that are perimetrically distributed through ferromagnetic cores of the field poles of the stator.