Compact centrifugal pump with magnetically suspended impeller

A pump apparatus comprising:

• a housing having a central axis and an inlet and an outlet adapted to respectively receive and discharge fluid;
• a rotor disposed in the housing and rotatable about the central axis, the rotor having an impeller adapted to pump fluid and magnetically suspended to maintain a flow channel between the rotor and the housing;
• an electric motor adapted to drive the rotor about a rotational axis substantially coincident with the central axis, the electric motor including a motor rotor assembly disposed in the rotor and a motor stator assembly disposed in the housing;
• a magnetic suspension device including:
• an annular rotor primary pole piece disposed in the rotor coaxially with the rotational axis, the annular rotor primary pole piece including a ferromagnetic material adapted to channel magnetic flux and having a first end surface, a second end surface, and a cylindrical side surface adapted to serve as a rotor pole face;
• a plurality of electromagnet units disposed in the housing and circumferentially distributed at regular intervals about the central axis, each electromagnet unit including:
• a pole shoe having a first pole shoe end surface, a second pole shoe end surface, and a side pole shoe cylindrical surface adapted to serve as a casing pole face;
• an iron core extending from the pole shoe;
• a back yoke connecting two or more of the iron cores of different electromagnet units together;
• and
• a coil wound around the iron core and adapted to conduct electric current;
• wherein the pole shoe, iron core, and back yoke include ferromagnetic material adapted to channel magnetic flux;
• wherein the first end surface of the rotor primary pole piece and the first end pole shoe surfaces of all the pole shoes are on a same side along an axial direction;
• wherein the rotor pole face and each of the casing pole faces oppose each other and define a primary suspension gap thereinbetween, the primary suspension gaps are axially aligned with each other and circumferentially separated from each other;
• at least one permanent magnet adapted to generate a plurality of bias magnetic fluxes, each of the bias magnetic fluxes radially passing through one of the primary suspension gaps, and passing through the rotor primary pole piece and of the pole shoe of the electromagnet unit;
• wherein the at least one permanent magnet is magnetized in such a direction that all the bias magnetic fluxes pass through the primary suspension gaps in a same polar direction;
• a plurality of position sensors disposed in the housing and circumferentially around the rotor, and adapted to detect a radial position of the rotor pole face;
• a feedback control system adapted to generate and deliver electric current into the coils of the plurality of electromagnet units according to a real-time output of the position sensors;
• wherein the feedback control system includes a control strategy adapted to achieve stability of radial positioning of the rotor;
• wherein the plurality of electromagnet units are electrically and magnetically connected to jointly generate a modulating magnetic flux for active control of the position of the rotor along any one of two orthogonal radial axes, a first radial axis having a first side and a second side divided by a second radial axis, the modulating magnetic flux radially passing through a plurality of the primary suspension gaps and superimposing the bias magnetic fluxes to enhance the bias magnetic flux in the primary suspension gap on the first side of the radial axis, and weaken the bias magnetic flux in the primary suspension gap on the second side of the radial axis.