JP4646393B2 - Control circuit of magnetic levitation pump - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a control circuit for a magnetic levitation pump, and more particularly, to a control circuit for controlling a magnetic levitation pump used in a medical device such as an artificial heart, which is a clean pump using a magnetic bearing.
[0002]
[Prior art]
FIG. 5 is a diagram showing a conventional magnetic levitation pump. In particular, FIG. 5 (a) is a longitudinal sectional view, and FIG. 5 (b) is a sectional view taken along line AA in FIG. 5 (a). is there.
[0003]
First, a conventional magnetic levitation pump will be described with reference to FIG. As shown in FIG. 5A, the magnetic levitation pump 1 includes a motor unit 10, a pump unit 20, and a magnetic bearing unit 30. A pump chamber 22 is provided in the casing 21 of the pump unit 20, and the impeller 23 rotates in the pump chamber 22. As shown in FIG. 5B, the impeller 23 has a plurality of blades 27 and is formed in a spiral shape.
[0004]
The casing 21 is made of a non-magnetic member, and the impeller 23 includes a non-magnetic member 25 having a permanent magnet 24 constituting a non-control type magnetic bearing, and a soft magnetic member 26 corresponding to a rotor of the control type magnetic bearing. The permanent magnet 24 is divided in the circumferential direction of the impeller 23, and adjacent magnets are magnetized by magnetic poles in opposite directions. The rotor 12 supported by the bearing 17 is provided outside the pump chamber 22 so as to face the side having the permanent magnet 24 of the impeller 23. The rotor 12 is driven by a motor 13 to rotate. The same number of permanent magnets 14 as the impeller 23 side are provided on the rotor 12 so as to face the permanent magnets 24 of the impeller 23 and to exert an attractive force. The permanent magnets 14 are also magnetized with magnetic poles adjacent to each other in opposite directions.
[0005]
On the other hand, on the circumference of the impeller 23 so as to face the side having the soft magnetic member 26, the pump chamber 22 balances the attractive force of the permanent magnets 24 and 14, and the impeller 23 can be held at the center of the casing 21. Three or more electromagnets 31 and position sensors 32 are provided in the magnetic bearing portion 30. The electromagnet 31 is C-shaped, and the position sensor 32 is a magnetic sensor.
[0006]
In the magnetic levitation pump 1 configured as described above, an axial absorption force acts between the permanent magnet 14 embedded in the rotor 12 and the permanent magnet 24 provided on the impeller 23. The impeller 23 is rotationally driven by the magnetic coupling using this attractive force, and the support rigidity in the radial direction is obtained. A current flows through the coil of the C-shaped electromagnet 31 so as to balance this attractive force, and the impeller 23 rises. When the rotor 12 is rotated by the driving force of the motor 13 including the motor rotor 15 and the motor stator 16, the permanent magnets 14 and 24 constitute a magnetic pole coupling, the impeller 23 rotates, and the fluid is sucked into the suction port 60. From the outlet 70 and discharged from the outlet 70. Since the impeller 23 is isolated from the rotor 12 by the casing 21 and does not receive contamination from the electromagnet 31, the fluid discharged from the magnetic levitation pump 1 (blood when used as a blood pump) is in a clean state. Hold.
[0007]
FIG. 6 is a diagram showing the magnetic levitation pump and control circuit shown in FIG. In FIG. 6, the magnetic levitation pump 200 is shown in a perspective view seen from the inlet 60 side of FIG. 5, and includes three electromagnets M 1, M 2 and M 3 around the rotation axis of the impeller 23. Sensors S1, S2 and S3 are arranged. The outputs of the sensors S1, S2, S3 are given to the sensor amplifiers H1, H2, H3, amplified, and given to the arithmetic circuit 202.
[0008]
The arithmetic circuit 202 calculates the sensor output amplified by the sensor amplifiers H1, H2, and H3, and sets the control voltage a proportional to the gap between the electromagnet M1 and the impeller 23, and the gap between the electromagnet M2 and the impeller 23. The proportional control voltage b and the control voltage c proportional to the gap between the electromagnet M3 and the impeller 23 are output and supplied to the phase compensation circuit 203.
[0009]
The phase compensation circuit 203 includes proportional differentiation circuits PD1, PD2, PD3 and integration circuits I1, I2, I3 to which the control voltages a, b, c are respectively applied. The outputs of the proportional differentiation circuits PD1, PD2, PD3 and the outputs of the integration circuits I1, I2, I3 are added and given to the limit circuits LM1, LM2, LM3. The limit circuits LM1, LM2, and LM3 are configured to pass only when the input signal is a positive voltage signal, and the negative voltage signal is forcibly set to 0V. Each output signal of limit circuit LM1, LM2, LM3 is applied to power amplifiers A1, A2, A3. The power amplifiers A1, A2, and A3 amplify the control voltages a, b, and c, respectively, and drive the corresponding electromagnets M1, M2, and M3. By these control circuits, the electromagnets M1, M2, M3 are individually calculated and driven based on the outputs of the sensors S1, S2, S3.
[0010]
FIG. 7 is a block diagram showing another example of the control circuit of the magnetic levitation pump. The control circuit shown in FIG. 6 is provided with a phase compensation circuit 203 having proportional differentiation circuits PD1, PD2, PD3 and integration circuits I1, I2, I3 independently for each electromagnet M1, M2, M3. The control circuit shown in FIG. 7 does not have a phase compensation circuit for each electromagnet independently, but is provided with a phase compensation circuit for each motion mode of each impeller controlled by a magnetic bearing. Here, the motion modes of the separated impeller 23 include a translational motion in the direction of the impeller rotational axis and a rotational motion about axes orthogonal to the impeller rotational axis, that is, a pitching motion and a yawing motion.
[0011]
The separation circuit 204 shown in FIG. 7 calculates sensor signals output from the sensor amplifiers H1, H2, and H3, and outputs a translational motion parameter z, an impeller pitching motion parameter θx, and an impeller yawing motion parameter θy of the impeller 23. In the same manner as in FIG. 6, the phase compensation circuit 205 includes proportional differentiation circuits PD1, PD2, PD3 and integration circuits I1, I2, I3 in consideration of each motion mode, and outputs of the respective electromagnets M1, M1 and I3. A current flows through each of the electromagnets M1, M2, and M3 via the limit circuits LM1, LM2, and LM3 and the power amplifiers A1, A2, and A3 via the distributor 206 for distributing to M2 and M3.
[0012]
[Problems to be solved by the invention]
When the magnetic levitation pump 1 shown in FIG. 5 is used for portable purposes or is embedded in a human body for use as a blood pump, the entire pump moves while the impeller 23 is rotating. The disk-shaped impeller 23 shown in FIG. 5 has a problem that a precession motion that causes the entire pump to swing around due to the influence of the gyro moment accompanying the rotational motion such as pitching and yawing during the rotation.
[0013]
When pitching or yawing motion is applied to the pump during the rotation of the impeller 23, a gyro moment proportional to the motion speed acts on the impeller 23. Due to this gyro moment, the impeller 23 has a gyro moment having a rotational axis orthogonal to the rotational motion (for example, pitching) applied as a disturbance to the pump, and the impeller 23 is displaced in the pump chamber 22, and this is further triggered by this. A low-frequency precession occurs in a direction opposite to the direction of rotation of the impeller 23.
[0014]
In particular, when the pump is used as a blood pump, if the casing 21 and the impeller 23 come into contact with each other due to the precession, it is easy to form a thrombus at that portion. Therefore, it is desirable to suppress this precession as much as possible. As a method for suppressing this, a method of increasing the size of the electromagnet and improving the rigidity of the magnetic bearing is conceivable. However, when the pump is used for an implantable blood pump, it is required to be as small as possible. Therefore, it cannot be adopted.
[0015]
Therefore, the main object of the present invention is to provide a stable impeller during rotation by compensating for the gyro moment generated against the rotational disturbance to the pump even if the pump is used for portable applications without increasing the pump size. It is to provide a control circuit of a magnetic levitation pump that can be supported.
[0017]
[Means for Solving the Problems]
This invention, together with the action of the electromagnetic attractive force on one side of the surface of the disc-shaped impeller, the impeller by applying either or both of the magnetic attraction force and the fluid force on the surface of the other side of the impeller A control circuit that controls a magnetic levitation pump that includes a plurality of sensors that are supported in a non-contact manner and that detect the position of the impeller and a plurality of electromagnets that position the impeller by applying an electromagnetic attractive force to the impeller. Each of the sensors and the plurality of electromagnets are arranged along one circle so as to face the surface on one side of the impeller. The control circuit is provided corresponding to each of the plurality of electromagnets, a signal generation circuit that generates a plurality of control signals indicating the distances between the plurality of electromagnets and the impeller based on the output signals of the plurality of sensors, respectively. A plurality of filter circuits for extracting a low frequency component from a control signal corresponding to a corresponding electromagnet and adding the extracted low frequency component to a control signal corresponding to an electromagnet adjacent in one direction along the circle of the corresponding electromagnet And a phase compensation circuit that is provided corresponding to each electromagnet, receives a corresponding control signal to which a low frequency component is added, and controls the electromagnetic attractive force of the corresponding electromagnet by proportional, differential, and integral elements, and includes an impeller It is characterized by compensating for a gyro moment generated during rotation.
Preferably, the amount of addition to the control signal of the low frequency component extracted by each filter circuit is changed based on the rotation speed of the impeller.
[0018]
In another invention, an electromagnetic attraction force is applied to the surface on one side of the disk-shaped impeller, and either or both of the magnetic attraction force and the fluid force are applied to the surface on the other side of the impeller. A control circuit that controls a magnetic levitation pump that includes a plurality of sensors that are supported in a non-contact manner and that detect the position of the impeller and a plurality of electromagnets that position the impeller by applying an electromagnetic attractive force to the impeller. Each of the sensors and the plurality of electromagnets are arranged along one circle so as to face the surface on one side of the impeller. The control circuit is provided corresponding to each of the plurality of electromagnets, and a signal generation circuit that generates a plurality of first signals indicating the distances between the plurality of electromagnets and the impeller based on the output signals of the plurality of sensors, A plurality of phase compensation circuits each receiving a corresponding first signal and generating a second signal for controlling the electromagnetic attraction force of the corresponding electromagnet by proportional, differential and integral elements; and Correspondingly provided, only the output signal of the integration element of the corresponding phase compensation circuit is generated by the phase compensation circuit corresponding to the electromagnet adjacent in one direction along the circle of the electromagnet corresponding to the corresponding phase compensation circuit. An addition circuit for adding to the second signal is provided, and a gyro moment generated when the impeller rotates is compensated.
Preferably, the amount of addition of the output signal of the integration element to the second signal is changed based on the rotation speed of the impeller.
[0019]
Therefore, according to the present invention, it is possible to compensate for the gyro moment generated against the rotation disturbance to the pump even when the pump is used for portable use, and it is possible to support an impeller that is stable during rotation.
[0021]
Furthermore, the magnetic levitation type pump is used for blood circulation.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a block diagram of a magnetic levitation pump and a control circuit according to an embodiment of the present invention.
[0023]
As described in the prior art, when pitching or yawing motion is applied to the pump during the rotation of the impeller 23, a gyro moment proportional to the motion speed acts on the impeller 23. Due to this gyro moment, the impeller 23 is subjected to a gyro moment having a rotational axis orthogonal to the rotational motion (for example, pitching) applied as a disturbance to the pump, and the impeller 23 is displaced in the pump chamber 22, and further, the impeller 23 is triggered by this. Precesses at a low frequency in the direction opposite to the direction of rotation. This is due to the interference between the pitching motion and yawing motion of the impeller due to the gyro moment, and in order to suppress this precession motion, it is necessary to eliminate the interference of both rotational motions at the frequency of this precession motion. In other words, it is only necessary to compensate by the control circuit of the magnetic bearing.
[0024]
In one embodiment of the present invention, it is configured to eliminate interference of both rotational motions in the frequency range of precession motion. That is, similarly to FIG. 6, the magnetic levitation pump is shown in a perspective view seen from the inlet 60 of FIG. 5, and includes three electromagnets M <b> 1, M <b> 2, M <b> 3 around the rotation axis of the impeller 23, Three sensors S1, S2 and S3 are arranged. The outputs of the sensors S1, S2, and S3 are given to the sensor amplifiers H1, H2, and H3, amplified, and given to the separation circuit 204. The separation circuit 204 calculates the sensor signals output from the sensor amplifiers H1, H2, and H3 in the same manner as in FIG. 7, and outputs the translational motion parameter z, the impeller pitching motion parameter θx, and the impeller yawing motion parameter θy of the impeller 23. To do.
[0025]
The impeller translational motion parameter z is provided to the phase compensation circuit 205, while the impeller pitching motion parameter θx and the impeller yawing motion parameter θy are provided to the circuit 207. The circuit 207 includes circuits 208 and 209 including a low-pass filter and a gain circuit, and addition circuits 210 and 211. The low-pass filters of the circuits 208 and 209 take out the precession component having the main component at the low frequency of the impeller 23, and the adder circuits 210 and 211 use the extracted precession component as another rotation. By adding to the motion mode control input, interference between the two rotational motions is suppressed. Since the influence of the gyro moment changes depending on the rotation speed of the impeller 23, optimal compensation can be achieved by changing the characteristics of the circuit 207 depending on the rotation speed of the impeller 23.
[0026]
The outputs of the adder circuits 210 and 211 are given to the phase compensation circuit 205, and currents are passed to the electromagnets M1, M2 and M3 via the distributor 206, limit circuits LM1, LM2 and LM3 and power amplifiers A1, A2 and A3. .
[0027]
As described above, in the embodiment of the present invention, the impeller pitching motion parameter θx and the impeller yawing motion parameter θy are given to the circuit 207, and the low-pass filters 208 and 209 reduce the precession motion component having the main component at the low frequency of the impeller. The precession component extracted by the adder circuits 210 and 211 is added to the control input of the other rotational motion mode to suppress interference between the pitching motion and yawing motion of the impeller, thereby enabling optimal compensation. .
[0028]
FIG. 2 is a block diagram showing another embodiment of the present invention. In the embodiment shown in FIG. 1 described above, the compensation of the precession is not changed by the impeller rotational speed, and the compensation of the circuit 207 acts as a disturbance on the control of the magnetic bearing when the impeller is not rotating. Actually, it is necessary to adjust the characteristics of the circuits 208 and 209 in advance so that the impeller 23 can be stably supported by the magnetic bearing even when the impeller is not rotating.
[0029]
On the other hand, in the embodiment shown in FIG. 2, an impeller rotational speed detector 212 for detecting the rotational speed of the impeller 23 is provided, and the characteristics of the circuits 208 and 209 are changed according to the output of the detector 212. It is designed to be variable. Therefore, according to this embodiment, the compensation for precession can be changed by the rotation speed of the impeller 23.
[0030]
FIG. 3 is a block diagram showing a control circuit of a magnetic levitation pump according to still another embodiment of the present invention. The embodiment shown in FIG. 3 is obtained by adding a circuit 213 to the control circuit shown in FIG. The circuit 213 computes the output of the sensor amplifiers H1, H2, and H3 and outputs a signal proportional to the distance between each of the electromagnets M1, M2, and M3 and the impeller 23 by circuits G1, G2, and G3 including a proportional circuit and a low-pass filter. By adding only the low frequency range to the calculation result of the distance between the adjacent electromagnet and the impeller, the precession due to the gyro moment is suppressed.
[0031]
FIG. 4 is a block diagram showing a control circuit of a magnetic levitation pump according to still another embodiment of the present invention. The embodiment shown in FIG. 4 is obtained by adding a circuit 214 to the control circuit shown in FIG. The circuit 214 multiplies the outputs of the proportional integration circuits I1, I2, and I3 controlled by the electromagnets by the proportional gains of ka, kb, and kc, respectively, and adds them to adjacent control circuits.
[0032]
The embodiment in which the compensation for the precession motion is changed according to the impeller rotational speed shown in FIG. 2 can also be applied to the embodiments in FIGS. 3 and 4.
[0033]
The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.
[0034]
【The invention's effect】
As described above, according to the present invention, it is possible to compensate for the gyro moment generated due to the rotation disturbance to the pump even when the pump is used for portable use without increasing the pump size, and stable during rotation. Thus, the impeller can be supported.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a control circuit of a magnetic levitation pump according to an embodiment of the present invention.
FIG. 2 is a block diagram of a control circuit of a magnetic levitation pump according to another embodiment of the present invention.
FIG. 3 is a block diagram showing a control circuit of a magnetic levitation pump according to still another embodiment of the present invention.
FIG. 4 is a block diagram showing a control circuit of a magnetic levitation pump according to still another embodiment of the present invention.
FIG. 5 is a cross-sectional view showing a magnetic levitation pump to which the present invention is applied.
6 is a block diagram of a control circuit for controlling the magnetic levitation pump shown in FIG. 5. FIG.
7 is a block diagram showing another example of a control circuit for controlling the magnetic levitation pump shown in FIG. 5. FIG.
[Explanation of symbols]
200 magnetic levitation pump, 204 separation circuit, 205 phase compensation circuit, 206 distribution circuit, 207, 213, 214 circuit, M1, M2, M3 electromagnet, S1, S2, S3 sensor, H1, H2, H3 sensor amplifier, 208, 209 A circuit composed of a low-pass filter and a gain circuit, 210 and 211 addition circuit.

Claims (5)

An electromagnetic attraction force is applied to the surface on one side of the disk-shaped impeller, and either or both of the magnetic attraction force and the fluid force are applied to the other surface of the impeller so that the impeller is contactless. A control circuit that controls a magnetic levitation pump including a plurality of sensors that support and detect the position of the impeller and a plurality of electromagnets that position the impeller by applying the electromagnetic attraction force to the impeller;
Each of the plurality of sensors and the plurality of electromagnets is arranged along one circle so as to face the surface on one side of the impeller,
A signal generation circuit that generates a plurality of control signals indicating the distances between the plurality of electromagnets and the impeller, based on output signals of the plurality of sensors;
Provided corresponding to each of the plurality of electromagnets, each extracting a low frequency component from a control signal corresponding to the corresponding electromagnet, and adjacent the extracted low frequency component in one direction along the circle of the corresponding electromagnet A plurality of filter circuits for adding to the control signal corresponding to the electromagnet to be
A phase compensation circuit which is provided corresponding to each electromagnet, receives a corresponding control signal to which the low frequency component is added, and controls the electromagnetic attraction force of the corresponding electromagnet by proportional, differential and integral elements;
A control circuit for a magnetically levitated pump, which compensates for a gyro moment generated when the impeller rotates. Additional amount for the control signal of the low-frequency component extracted by the filter circuit is characterized in that it is changed based on the rotational speed of the impeller, magnetic control circuit of the levitation type pump according to claim 1. An electromagnetic attraction force is applied to the surface on one side of the disk-shaped impeller, and either or both of the magnetic attraction force and the fluid force are applied to the other surface of the impeller so that the impeller is contactless. A control circuit that controls a magnetic levitation pump including a plurality of sensors that support and detect the position of the impeller and a plurality of electromagnets that position the impeller by applying the electromagnetic attraction force to the impeller;
Each of the plurality of sensors and the plurality of electromagnets is arranged along one circle so as to face the surface on one side of the impeller,
A signal generation circuit for generating a plurality of first signals indicating distances between the plurality of electromagnets and the impeller, based on output signals of the plurality of sensors,
Each corresponding to the plurality of electromagnets, each receiving a corresponding first signal and generating a second signal for controlling the electromagnetic attraction force of the corresponding electromagnet by proportional, differential and integral elements. A plurality of phase compensation circuits;
Phase compensation corresponding to the electromagnet adjacent in one direction along the circle of the electromagnet corresponding to the phase compensation circuit, provided only for the output signal of the integration element of the corresponding phase compensation circuit, provided corresponding to each phase compensation circuit An adder circuit for adding to the second signal generated by the circuit;
A control circuit for a magnetically levitated pump, which compensates for a gyro moment generated when the impeller rotates. 4. The control circuit for a magnetic levitation pump according to claim 3 , wherein the amount of addition of the output signal of the integration element to the second signal is changed based on the rotational speed of the impeller. The maglev pump, characterized in that it is used in the blood circulation, the control circuit of the magnetic levitation type pump according to any one of claims 1 to 4.

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