Abstract:
There is provided a fluid pump wherein in a casing at a pump unit there is provided an impeller coupled with a rotor contactless and also supported contactless by a controlled magnetic bearing unit, and rotated by a motor to output a fluid, with a position detection unit, an electromagnet or a motor stator cooled by a fluid flowing through a pump chamber.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to fluid pump apparatus and more specifically to those for use for example for artificial hearts, employing a magnetic bearing to magnetically levitate an impeller to deliver fluid such as blood. 
     2. Description of the Background Art 
     FIG. 15 is a vertical cross section of one example of a body of a blood pump as one example of a conventional fluid pump apparatus. In FIG. 15, the pump body includes a cylindrical housing  1  internally partitioned axially by partitions  11 ,  12 ,  13  and  14  to accommodate an electromagnet unit  20 , a pump unit  30  and a motor unit  40 . Electromagnet unit  20  has an electromagnet  21  and a magnetic bearing sensor  22  incorporated therein. Casing  1  has on the electromagnet unit  20  side (or one side) a side wall having a center provided with an inlet  15  introducing blood. At least three electromagnets  21  and at least three magnetic bearing sensors  22  surround inlet  15  circumferentially. Electromagnets  21  and magnetic bearing sensors  22  are attached to an internal wall surface of partition  11  externally isolating electromagnet unit  20 . 
     In pump unit  30  an impeller  31  is rotatably housed and it has a portion closer to electromagnet unit  20  that is supported by electromagnet unit  21  contactless through partition  12 , and magnetic bearing sensor  22  senses the distance between magnetic bearing sensor  22  and one side of impeller  31 . Impeller  31  has the other side with a plurality of permanent magnets  32  buried therein circumferentially. 
     Motor unit  40  houses a motor stator  41  and motor rotor  42 . Motor stator  41  is arranged on an external peripheral surface of a cylindrical member  43  extending cylindrically from an internal wall surface of partition  14  externally partitioning motor unit  40 . Motor rotor  42  rotates around a shaft supported by an internal peripheral surface of cylindrical member  43  via a motor bearing  44  provided in the form of a ball or roller bearing. Motor rotor  42  has an inner peripheral surface provided with a permanent magnet  47  facing an electromagnet  46  of motor stator  41  and motor rotor  42  rotates through their magnetic force, borne by motor bearing  44 . Motor rotor  42  has a surface facing pump unit  30  and having a plurality of permanent magnets  45  buried therein circumferentially, opposite to permanent magnet  32  buried in impeller  31 , through partition  13 . 
     In the blood pump apparatus thus configured, magnetic bearing sensor  22  provides an output which is referred to by a controller  10 , described hereinafter, to control a current flowing to electromagnet  21 , to control an attractive force provided by electromagnet  21  toward the opposite side of impeller  31 . 
     Furthermore impeller  31  has a portion closer to motor unit  40  that is affected by the attractive force introduced by permanent magnets  32  and  45 . And impeller  31  is magnetically levitated by a non-controlled bearing provided by permanent magnets  32  and  45  and a controlled bearing provided by electromagnet  21 . Impeller  31  is rotated by a driving force of motor unit  40  and blood introduced through inlet  15  is output through an outlet (not shown) formed at pump unit  30 . 
     In the FIG. 15 fluid pump apparatus, electromagnet  21  generates heat attributed to a current flowing to magnetically levitate impeller  31  and motor stator  41  generates heat attributed to a current flowing to rotate motor rotor  42 . Furthermore, motor bearing  44  is provided for example in the form of a ball or roller bearing and generates heat through friction as motor rotor  42  rotates. Furthermore, to externally release the heat generated by electromagnet  21 , electromagnet  21  and magnetic bearing sensor  22  are fixed on an internal wall surface of partition  11  provided in contact with an outside of casing  1 , and motor stator  41  is also provided at an internal wall surface of partition  14  provided in contact with an outside of casing  1 , at an external peripheral surface of cylindrical member  43 . Thus casing  1  is increased in temperature by the heat generated by electromagnet  21  and motor stator  41 . 
     When the heat increases temperature, the heat is transferred to magnetic bearing sensor  22  and the sensor consequently has a temperature drift, which disadvantageously results in unreliable sensing. 
     Furthermore if fluid pump apparatus in FIG. 15 is used for example as a blood pump and thus configures a portion of an artificial heart and implanted in a human body the heat generated as described above may have a negatively effect on the tissues of the human body. This needs to be addressed by an approach taken separately. Such approaches to be taken, however, would increase the blood pump in size. Thus it is impossible to reduce the blood pump for the artificial heart in size or weight. 
     FIG. 16 is a block diagram showing a controller driving the conventional fluid pump apparatus shown in FIG.  15 . 
     In FIG. 16, controller  10  includes a sequence circuit  101  externally receiving a control signal corresponding to commands for rotation, levitation and the like, an AC-DC converter  102  receiving an AC power supply, and a monitor circuit  103  monitoring the blood pump&#39;s operation and externally communicating the condition. AC-DC converter  102  converts an AC voltage to a DC voltage which is in turn applied to a motor power amplifier  104 , a magnetic bearing power amplifier  124  and a DC-DC converter  105 . DC-DC converter  105  stabilizes the DC voltage and supplies it to a circuit as described hereinafter. 
     Controller  10  also includes a sensor circuit  110  having a carrier wave generation circuit  111 , a tuning circuit  112  and an amplifier  113  incorporated therein. Carrier wave generation circuit  111  generates a carrier wave which is in turn provided via a connector  150  to magnetic bearing sensor  22  housed in housing  1  of the pump body. Magnetic bearing sensor  22 , as shown in FIG. 15, outputs a signal having an amplitude corresponding to a distance between magnetic bearing sensor  22  and impeller  31 . Tuning circuit  112  is tuned in to the signal to extract a detection signal, amplifier  113  amplifies the detection signal and provides it to magnetic bearing control circuit  121 . 
     A magnetic bearing control circuit  121  receives the detection signal, responsively provides PID control, and feeds the control output to a magnetic bearing PWM circuit  122 . Magnetic bearing PWM circuit  122  uses pulse width modulation (PWM) to vary the received control signal in pulse width. A magnetic bearing gate drive circuit  123  is operative to control a magnetic bearing power amplifier  124  to drive electromagnet  21 . 
     Furthermore, a motor control circuit  131  outputs to a motor PWM circuit  132  a control signal based on a command input to sequence circuit  101 . Motor PWM circuit  132  outputs a PWMed control signal to a motor gate drive circuit  133 . Motor gate drive circuit  133  outputs a drive signal to motor power amplifier  104 . In response to the drive signal, motor power amplifier  104  drives motor stator  41 . 
     In the blood pump apparatus shown in FIGS. 15 and 16, magnetic bearing sensor  22  has characteristics slightly varying to reflect a difference of an individual blood pump from another individual one. As such, in sensor circuit  110  an adjustment needs to be made for each sensor. As such, controller  10  is not compatible with each blood pump, which is a bottleneck in mass production. 
     Furthermore, magnetic bearing power amplifier  124 , motor power amplifier  104  and the like generate significant heat attributed to switching-loss and controller  10  would also generate heat, which can have a negative effect on a human body when the apparatus is implanted therein. 
     SUMMARY OF THE INVENTION 
     Therefore a main object of the present invention is to provide a fluid pump apparatus reduced in size and weight and capable of efficiently release heat. 
     Another object of the present invention is to provide a fluid pump apparatus capable of providing compatibility between the pump body and the controller and also using blood to cool a heated portion thereof. 
     The present invention provides a fluid pump apparatus including: a pump unit having in a casing a rotative member rotated to output a fluid; a drive unit coupled with one side of the rotative member contactless through a magnetic force to levitate one side of the rotative member while rotatably driving one side of the rotative member; a position detection unit detecting a position of the rotative member in levitation; and a controlled magnetic bearing unit contactlessly supporting the other side of the rotative member in response to an output of the position detection unit, wherein heat generated at least one of the rotative member, the position detection unit and the controlled magnetic bearing unit is released via a fluid flowing through the pump unit. 
     Thus in accordance with the present invention if a position detection unit receiving a sensor output to determine the position of the impeller in levitation is housed in the casing the position detection unit can have characteristics adjusted to correspond to the sensor of the body of the fluid pump to maintain compatibility with a controller. 
     Furthermore, if any of a drive circuit controlling the drive unit or a magnetic bearing control circuit controlling the controlled magnetic bearing unit is housed in the casing then heat generated from the drive circuit can be efficiently cooled by a fluid to prevent the controller body from generating significant heat. 
     Preferably, the casing includes a first partition provided between the pump unit and the drive unit and a second partition provided between the pump unit and the controlled magnetic bearing unit, and the drive unit is attached to the first partition and the controlled magnetic bearing unit is attached to the second partition. 
     More preferably the position detection unit is attached to the second partition. 
     Still more preferably, the rotative member is formed in a disk having a side facing the drive unit and provided with a permanent magnet arranged circumferentially and the rotative member and the drive unit are coupled contactless through magnetic-coupling. 
     Still more preferably, the rotative member is formed in a disk having a side facing the drive unit and provided with a first permanent magnet arranged circumferentially, the drive unit is provided with a second permanent magnet arranged circumferentially to face the first permanent magnet, and the first and second permanent magnets provide magnetic-coupling to couple the rotative member and the drive unit together contactlessly. 
     Still more preferably the controlled magnetic bearing unit includes a plurality of electromagnets each configured of a magnetic pole, a yoke and a coil and having an S magnetic pole and an N magnetic pole with at least the yoke and coil arranged circumferentially. 
     Still more preferably the drive unit includes a motor stator and a motor rotor rotated by a magnetic force of the motor stator, the motor stator being attached to the second partition. 
     Still more preferably the pump unit has an internal surface coated with an antithrombotic substance such as heparin. 
     The present invention in another aspect provides a fluid pump having a casing, an impeller driven, levitated, a drive unit driving the impeller, a sensor sensing a position of the impeller in levitation, and a controlled magnetic bearing unit contactlessly supporting the impeller in response to an output of the sensor, wherein the casing has housed therein at least one of the following circuits. The position detection circuit operative in response to the output of the sensor to determine the position of the impeller in levitation, the drive circuit controlling the drive unit, and the magnetic bearing control circuit controlling the controlled magnetic bearing. 
     If the position detection circuit is housed in the casing the position detection circuit can be adjusted to correspond to characteristics of the incorporated sensor and thus maintain compatibility with a controller. If the drive circuit or the magnetic bearing control circuit is housed in the casing, heat generated from the circuits can be cooled with a fluid flowing into the pump. 
     Preferably the fluid pump further includes an alternating current to direct current conversion circuit converting an alternating-current voltage to a direct-current voltage, and a direct current to direct current conversion circuit converting the converted direct-current voltage to a different direct-current voltage, wherein the direct current to direct current conversion circuit is housed in the casing. In this example also heat generated at the direct current to direct current conversion circuit can be cooled by a fluid. 
     More preferably the fluid pump apparatus further includes: a carrier wave generation circuit generating a carrier wave; and a tuning circuit detecting a signal of the sensor tuned in to the carrier wave generated by the carrier wave generation circuit, to detect the position of the impeller in levitation, wherein the carrier wave generation circuit and the tuning circuit are housed in the casing. As such, by adjusting the carrier wave generation circuit and the tuning circuit to correspond to the sensor&#39;s characteristics, compatibility with a controller can be achieved. 
     The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the drawings: 
     FIG. 1A is a vertical cross section of one embodiment of the present invention and FIG. 1B is a cross section thereof taken along line IB—IB of FIG. 1A; 
     FIG. 2 is a cross section taken along line II—II of FIG. 1A; 
     FIG. 3 is a cross section taken along line III—III of FIG. 1A; 
     FIG. 4 is a block diagram showing a controller controlling a fluid pump apparatus of the present invention; 
     FIG. 5 is a vertical cross section of another embodiment of the present invention; 
     FIGS. 6-14 are block diagrams showing second to tenth embodiments of the controller of the present invention; 
     FIG. 15 is a vertical cross section of a body of a conventional blood pump; and 
     FIG. 16 is a block diagram showing a controller driving a conventional fluid pump. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIGS. 1A and 1B show a fluid pump apparatus of one embodiment of the present invention. More specifically, FIG. 1A is a vertical cross section thereof and FIG. 1B is a cross section thereof taken along line IB—IB of FIG.  1 A. FIG. 2 is a cross section taken along line II—II of FIG.  1 A and FIG. 3 is a cross section taken along line III—III of FIG.  1 A. 
     In the FIG. 15, aforementioned conventional example, electromagnet  21  is attached to an internal wall surface of partition  11  provided in contact with an outside of casing  1  and motor stator  31  is also attached to an internal wall surface of partition  14  provided in contact with an outside of casing  1 . In the FIG. 1A embodiment, by contrast, they are attached to wall surfaces of partitions  12  and  13  separating pump unit  30  and a fluid flowing through pump chamber  33 , such as blood, cools electromagnet  21  and motor stator  31 . 
     More specifically, the fluid pump apparatus includes a cylindrical casing  1  axially partitioned by partitions  11 ,  12 ,  13  and  14  to have sections housing a magnetic bearing unit  20 , a pump unit  30  and a motor unit  40 , respectively. Casing  1  is formed for example of plastic, ceramic, metal or the like, although of casing  1 , partition  12  provided between magnetic bearing unit  20  and pump unit  30  and partition  13  provided between pump unit  30  and motor unit  40  are not allowed to be formed of magnetic material. Therefore they are accordingly formed of non-magnetic material. 
     At pump unit  30  casing  1  is internally provided with a pump chamber  33  in which an impeller  31  rotates to output a fluid through an outlet  16  (FIG.  1 B). Impeller  31  has a plurality of vanes  34  spirally provided, as shown in FIG.  1 B. Impeller  31  includes a non-magnetic member  35  having a permanent magnet configuring a non-controlled magnetic bearing and a soft magnetic member  36  corresponding to a rotor of a controlled magnetic bearing. Permanent magnet  32  is divided in a circumferential direction of impeller  31  and adjacent magnets are magnetized to have opposite magnetic poles. 
     Note that by coating the entire interior of pump chamber  33  with heparin or a similarly antithrombotic substance serving as an anticoagulant, formation of thrombus can be prevented therein and the fluid pump apparatus can thus be used as a blood delivering pump. In this example, the antithrombotic coating can effectively limit activation of coagulation system, protect platelets, limit activation, activation of inflammation system, activation of fibrinolysis system, and the like. 
     In FIGS. 1A and 1B, non-magnetic member  35  and soft magnetic member  36  are shown hatched. If the pump is used to deliver a corrosive fluid such as blood, the soft magnetic material is preferably a highly corrosive-resistant, ferritic stainless steel (SUS447J1, SUS444 or the like) and the non-magnetic material is preferably a highly corrosive-resistant, austenitic stainless steel (SUS316L or the like) or titanium alloy, pure titanium or the like. 
     Opposite to a side of impeller  31  having permanent magnet  32 , a cylindrical member  48  is provided in motor unit  40 , extending from a center of partition  13  toward partition  14 . Cylindrical member  48  has an external peripheral surface provided with a motor bearing  49  provided in the form of a ball and roller bearing which supports motor rotor  46  rotatably. Cylindrical member  48  has an end with a motor stator  47  attached thereto. Motor rotor  46  is driven by motor stator  47  to rotate. Motor rotator  46  is circumferentially provided with the same number of permanent magnets  45  as permanent magnets  32  of impeller  31  opposite thereto to provide attractive force. Adjacent permanent magnets  45  are magnetized to have opposite magnetic poles. 
     Note that while the motor is a synchronous motor including a DC brushless motor, a non-synchronous motor including an induction motor, or the like, it may be any kind of motor. 
     Provided in electromagnet unit  20  are an electromagnet  23  and a magnetic bearing sensor  24 , attached on a wall of partition  12  provided between electromagnet unit  20  and pump unit  30 , opposite to that side of impeller  31  having soft magnetic member  36 . Electromagnet  23  and magnetic bearing sensor  24  allow impeller  31  to be held at the center of pump chamber  33 , matching the attractive force produced between permanent magnets  32  and  45 . 
     Thus the heat generated at electromagnet  23  can be transferred to partition  12  and thus cooled by a fluid existing in pump unit  30 . Similarly, the heat generated at motor stator  47  is also transferred through cylindrical member  48  to partition  13  and thus cooled by the fluid existing in motor unit  30 . This can reduce heat transfer to outside casing  1  and also reduce heat transfer to magnetic bearing sensor  24  to provide a reliable sensing operation. Furthermore, if partitions  12  and  13  are increased in thickness to have a level of strength allowing electromagnet  23 , magnetic bearing sensor  24  and motor stator  47  to be attached thereto, housing  1  can advantageously have an outer-diameter portion reduced in thickness. 
     Electromagnet  23  and magnetic bearing sensor  24  are arranged, as shown in FIGS. 2 and 3. More specifically, a plurality of paired, circumferentially arranged electromagnets  23  have magnetic poles  51  and  52  with a sensor  241  arranged therebetween, magnetic poles  53  and  54  with a sensor  242  arranged therebetween, and magnetic poles  55  and  56  with a sensor  243  arranged therebetween. Sensors  241  to  243  are typically a magnetic sensor, such as an eddy-current sensor, a reluctance sensor or the like. 
     Furthermore, as shown in FIG. 3, electromagnets  23  have their respective yokes  71 - 76  in the form of a column circumferentially arranged with electromagnet coils  81 - 86  wound therearound, respectively. 
     Circumferentially arranging magnetic poles  51 - 56  can increase the space housing electromagnet coils  81 - 86  that can be housed in magnetic bearing unit  40 . This ensures a large space for winding the coils without increasing the size of the pump. Increasing a space for housing a coil in turn allows an electromagnet coil to have an increased turn count and an increased wire diameter and can thus save power for the electromagnet. 
     Furthermore, electromagnet yokes  71 - 76  in the form of a column can facilitate winding electromagnet coils  81 - 86  around electromagnet yokes  71 - 76 , respectively. Electromagnet yokes  71 - 76  having a simple geometry ensures insulation from electromagnet coils  81 - 86 . While electromagnet yokes  71 - 76  are cylindrical, they may be in the form of a prism, which can facilitate winding coils and thus ensuring an insulation withstand voltage between the coils and the yokes. 
     Furthermore while in FIGS. 2 and 3 electromagnet yokes  71 - 76  and electromagnet coils  81 - 86  are all arranged in a single circle, they may not be thus arranged if required to effectively ensure a space for housing the same. 
     With the magnetic bearing having each electromagnet with its magnetic pole and yoke arranged circumferentially, the magnetic bearing unit is not required to have a large space and the electromagnet yoke can also be provided in a cylinder or a prism to facilitate winding the coil and consequently ensuring an insulation withstand voltage between the coil and the yoke. 
     FIG. 4 is a block diagram showing a first embodiment of a controller for driving a magnetically levitated (maglev) pump in one embodiment of the present invention. In FIG. 4, a controller  200  includes a function provided to control the position of the impeller, a function provided to control the running torque of the impeller, a function using the impeller position control function to change the position of impeller  31  levitating in pump chamber  33 , a function provided to measure the current of motor unit  40 , and a function provided to calculate a viscosity of a fluid from a variation in current in motor unit  40  that is introduced when the function controlling the position of the impeller in levitation is operated to change the position of impeller  31  in levitation. 
     More specifically, controller  200  includes a controller body  201 , a motor driver  202  and a control unit  203  provided to control the impeller&#39;s position. Motor driver  202  is provided to rotate motor unit  40 , outputting a level of voltage corresponding to a motor rotation rate output from controller body  201 . Control unit  203  maintains the impeller position in levitation output from controller body  201 , controlling either one or both of a current flowing through and a voltage applied to electromagnet  23 . 
     Magnetic bearing sensor  24  provides an output which is in turn input to control unit  203  to control a current flowing through electromagnet  23  to control the impeller  31  translation along its center axis (an axis z) and the impeller  31  rotation around axes x and y orthogonal to the center axis (axis z). Note that the output from magnetic bearing sensor  24  may be input to controller body  201  which is adapted to in turn output a voltage or current value applied to electromagnet  23 . 
     Controller body  201  includes a storage unit (ROM)  204 , a CPU  205 , a display unit  210 , and an input unit  207 . Display unit  210  includes a set flow rate (SFR) display unit  211 , a real flow rate (RFR) unit  212 , a set pressure (SP) display unit  213 , a real pressure (RP) display unit  214 , a fluid temperature (FT) display unit  215 , a fluid viscosity (FV) display unit  216 , and an impeller speed (IS) display unit  217 . 
     Furthermore, input unit  207  includes an SFR input unit  208  and an SP input unit  209 . 
     Controller body  201  includes a data storage unit storing data of a relationship between fluid viscosity and motor current valiance, corresponding to a previously obtained relationship between fluid viscosity and motor current valiance depending on positional variance of the impeller in levitation (variance in motor drive current), or a relationship expression calculated from the data related to such relationship (for example data of a correlation expression or data of an expression of viscosity calculation), and the function provided for calculation of fluid viscosity calculates fluid viscosity from the data stored in storage unit  24  and the valiance of the current through motor unit  40  obtained when the impeller  23  position in levitation is changed via the function controlling the impeller position in levitation. 
     In other words, controller body  201  at storage unit  204  stores data related to a relationship between fluid viscosity and motor current variance corresponding to a previously obtained relationship between fluid viscosity and motor current variance depending on positional change of the impeller in levitation, or correlation data calculated from the data related to such relationship (also serving as data of an expression for viscosity calculation). 
     FIG. 5 is a vertical cross section of a fluid pump in another embodiment of the present invention. The present embodiment differs from the FIG. 1A embodiment only in a motor unit  50 , and the embodiments are identical in electromagnet unit  20  and pump unit  30  and will thus not be described repeatedly. 
     In the FIG. 1A embodiment, motor unit  40  includes motor stator  47  provided with a coil and motor rotor  47  provided with a permanent magnet and arranged closer to pump unit  30 . In the FIG. 5 embodiment, in contrast, a motor stator  51  is provided with a coil which cooperates with permanent magnet  32  of impeller  31  to provide a magnetic force to rotate impeller  31 . 
     In the present embodiment, motor stator  51 , generating heat, is also attached to partition  13  so that the heat of motor stator  51  can be cooled by a fluid existing in pump unit  30 . 
     FIG. 6 is a block diagram showing a second embodiment of the controller in accordance with the present invention. In the present embodiment, sensor circuit  110  is accommodated in a pump body  1   a . A DC voltage is supplied from a controller  10   a  via a connector  50  to sensor circuit  110 . Sensor circuit  110  provides an output which is in turn input via connector  50  to magnetic bearing control circuit  121 . Sensor circuit  110  is configured including carrier wave generation circuit  111 , tuning circuit  112  and amplifier  113 , as shown in FIG.  16 . 
     Controller  10   a  includes sequence circuit  101  receiving an external control signal including commands for rotation, levitation and the like, AC-DC converter  102  receiving an AC power supply, and monitor circuit  103  monitoring the blood pump&#39;s operation to externally communicate the condition thereof. Controller  10   a  also includes motor power amplifier  104 , magnetic bearing power amplifier  124  and DC-DC converter  105  all receiving a direct-current power supply from AC-DC converter  102 . Controller  10   a  also includes magnetic bearing PWM circuit  122 , magnetic bearing gate drive circuit  123 , motor control circuit  131 , motor PWM circuit  132 , and motor gate drive circuit  133 . These circuits operate and are connected as has been previously described with reference to FIG.  16  and will thus not be described repeatedly. 
     In the FIG. 6 embodiment, sensor circuit  110 , housed in pump body  1   a , can be adjusted to correspond to magnetic bearing sensor  24 , which allows compatibility with controller  10   a.    
     In the third to tenth embodiments described hereinafter, the circuits denoted by the same reference characters as in FIG. 16 operate and are connected in the same manners as described and shown in the figure and they will thus not be described repeatedly. Only the circuits incorporated in pump bodies  1   b - 1   i  will be described and the other circuits incorporated in controllers  10   b - 10   i  will not be described. 
     FIG. 7 shows a third embodiment of the controller in accordance with the present invention. In the present embodiment, magnetic bearing power amplifier  124  and motor power amplifier  104 , both generating significant heat attributed to switching-loss, are incorporated in pump body  1   b . In this example, magnetic bearing power amplifier  124  and motor power amplifier  104  also receive a direct-current voltage from AC-DC converter  102  provided in controller  10   b , via connector  50 . 
     In the present embodiment, magnetic bearing power amplifier  124  and motor power amplifier  104  that are incorporated in pump body  1   b  can have their heat cooled by blood delivered by pump body  1   b . This can prevent controller  10   b  from generating significant heat. 
     Note that in the FIG. 7 embodiment pump body  1   b  may have incorporated therein not only magnetic bearing power amplifier  124  and motor power amplifier  104  but also a sensor circuit  110 , as shown in FIG.  1 A. Advantageously this can not only prevent controller  10   b  from generating significant heat but provide compatibility between pump body  1   b  and controller  10   b.    
     FIG. 8 is a block diagram showing a fourth embodiment of the controller in accordance with the present invention. In the present embodiment, a pump body  1   c  has incorporated therein sensor circuit  110 , motor control circuit  131 , motor PWM circuit  132 , motor gate drive circuit  133  and motor power amplifier  104 . Controller  10   c  is provided with the remaining configuration. 
     In the present embodiment, pump body  1   c  has sensor circuit  110  incorporated therein to have compatibility with controller  10   c  and pump body  1   c  also only have a motor-related configuration incorporated therein to prevent the body from having a large size. 
     FIG. 9 is a block diagram showing a fifth embodiment of the controller in accordance with the present invention. In the present embodiment, a pump body  1   d  has incorporated therein magnetic bearing PWM circuit  122 , magnetic bearing gate drive circuit  123  and magnetic bearing power amplifier  124  provided to control electromagnet  23  (hereinafter these three circuits will generally be referred to as a system driving electromagnet  23 ) and also has incorporated therein motor PWM circuit  132 , motor gate drive circuit  133  and motor power amplifier  104  provided to control motor stator  41  (hereinafter these three circuits will generally be referred to as a system driving motor stator  67 ). 
     In the present embodiment a circuit portion dealing with a switching signal, such as magnetic bearing PWM circuit  122  and motor PWM circuit  132 , can be incorporated in pump body  1   d . As such, electromagnet  23 , motor stator  67  and their driving systems can be less distant from each other to as a result provide a control signal free of significantly impaired quality and significant distortion: Such an impaired or distorted control signal would result in heat generation, which can be limited in the present embodiment. Furthermore, controller  10   d  has incorporated therein sensor circuit  110 , magnetic bearing control circuit  121 , motor control circuit  131  and the like. 
     FIG. 10 is a block diagram showing a sixth embodiment of the controller in accordance with the present invention. The present embodiment is the FIG. 4 embodiment plus the FIG. 1A embodiment, not only the electromagnet  23  and motor stator  67  driving systems but also sensor circuit  110  incorporated in a pump body  1   e , to achieve a combination of the effects of the FIGS. 6 and 9 embodiments. 
     FIG. 11 is a block diagram showing a seventh embodiment of the controller in accordance with the present invention. In the present embodiment, sensor circuit  110  and the electromagnet  23  driving system are preferentially incorporated in a pump body  1   f.    
     FIG. 12 is a block diagram showing an eighth embodiment of the controller in accordance with the present invention. In the present embodiment, sensor circuit  110 , the electromagnet  23  and motor stator  67  driving systems are incorporated in a pump body  1   g , and other circuits including a power supply circuit, a sequence circuit and a monitor circuit are incorporated in a controller  10   g.    
     FIG. 13 is a block diagram showing a ninth embodiment of the controller in accordance with the present invention. A controller  10   h  only has incorporated therein AD-DC converter  102  and DC-DC converter  105 , and pump body  1   h  has incorporated therein the remaining, sequence circuit  101 , monitor circuit  103 , sensor circuit  110 , and the electromagnet  23  and motor stator  67  driving systems. 
     FIG. 14 is a block diagram showing a tenth embodiment of the controller in accordance with the present invention. In the present embodiment a controller  10   i  only has incorporated therein AC-DC converter  102  and a pump body  1   i  has incorporated therein all of the remaining components. 
     Although in the FIGS. 11-14 embodiments a pump body has a driving system incorporated therein and it is thus increased in size, the embodiments are advantageous as a satisfactory heat sink effect can be achieved and the pump body and the controller can have compatibility therebetween. 
     Thus in accordance with the embodiments of the present invention if a position detection circuit receiving a sensor output to determine the position of the impeller in levitation is housed in the casing the position detection circuit can have characteristics adjusted to correspond to the sensor of the body of the blood pump to maintain compatibility with the controller. 
     Furthermore, if any of a drive circuit controlling the drive means or a magnetic bearing control circuit controlling the controlled magnetic bearing unit is housed in the casing then heat generated from the drive circuit can be efficiently cooled by a fluid to prevent the controller body from generating significant heat. 
     Although the present invention has been described and illustrated in detail, it is clearly understood that the same is by way of illustration and example only and is not to be taken by way of limitation, the spirit and scope of the present invention being limited only by the terms of the appended claims.