Control device for a magnetic bearing, centrifugal compressor and electric appliance

Abstract

The application discloses a control device of a magnetic suspension bearing, a centrifugal compressor and an electrical appliance. The magnetic suspension bearing comprises a rotor, a radial bearing and an axial bearing which are arranged around the rotor. The radial bearing and the axial bearing are provided with a constant current source coil and an electromagnetic coil. The control device comprises: a constant current source control unit connected with the constant current source coil, which is used for controlling the constant current source coil to generate a bias magnetic field; and a bearing control unit connected with the electromagnetic coil, which is used for acquiring the position of the rotor and controlling the electromagnetic coil to generate a control magnetic field according to the position, so that the rotor is in a target position under the joint action of the control magnetic field and the bias magnetic field. The device can reduce the heat generation of the power driving part, thereby prolonging the service life of the magnetic suspension bearing, and can reduce the cost of the magnetic suspension bearing and stabilize the control, thereby solving the problems of high cost of the permanent magnet bias magnetic suspension bearing, large heat generation and low service life of the existing electromagnetic magnetic suspension bearing.

Description

Technical Field

[0001] This invention relates to the field of electrical equipment technology, and in particular to a control device for a magnetic levitation bearing, a centrifugal compressor, and electrical equipment. Background Technology

[0002] Magnetic levitation bearings utilize electromagnetic force to overcome the rotor's gravity, causing the rotor to levitate and thus eliminating mechanical contact between the rotor and stator. They are characterized by being oil-free, frictionless, and having a long service life, and are widely used in ultra-high-speed applications such as flywheel energy storage, aerospace equipment, and large centrifuges.

[0003] In related technologies, traditional magnetic levitation bearings include permanent magnet biased magnetic levitation bearings and pure electromagnetic magnetic levitation bearings. Permanent magnet biased magnetic levitation bearings are expensive and not suitable for low-cost, large-scale applications; while pure electromagnetic magnetic levitation bearings are large in size and consume a lot of power. Because electromagnetic bearings need to provide a large bias current, the power drive components are prone to damage. Summary of the Invention

[0004] This invention aims to at least partially solve one of the technical problems in related technologies. Therefore, the first objective of this invention is to provide a control device for a magnetic levitation bearing that can reduce the heat generated by the power drive components, thereby extending the service life of the magnetic levitation bearing, reducing its cost, and providing stable control. This addresses the problems of high cost of permanent magnet bias magnetic levitation bearings and high heat generation and short lifespan of existing electromagnetic magnetic levitation bearings.

[0005] The second objective of this invention is to provide a centrifugal compressor.

[0006] The third objective of this invention is to provide an electrical device.

[0007] To achieve the above objectives, a first aspect of the present invention provides a control device for a magnetic levitation bearing. The magnetic levitation bearing includes a rotor, a radial bearing and an axial bearing arranged around the rotor, and a constant current source coil and an electromagnetic coil are arranged on the radial bearing and the axial bearing. The control device includes: a constant current source control unit connected to the constant current source coil, used to control the constant current source coil to generate a bias magnetic field; and a bearing control unit connected to the electromagnetic coil, used to obtain the position of the rotor and control the electromagnetic coil to generate a control magnetic field according to the position, so that the rotor is at a target position under the combined action of the control magnetic field and the bias magnetic field.

[0008] According to an embodiment of the present invention, a control device for a magnetic levitation bearing includes a constant current source control unit that controls a constant current source coil to generate a bias magnetic field. The bearing control unit acquires the rotor's position and, based on this position, controls an electromagnetic coil to generate a control magnetic field, so that the rotor is positioned at a target location under the combined action of the control magnetic field and the bias magnetic field. Therefore, this device can reduce the heat generated by the power drive components, thereby extending the service life of the magnetic levitation bearing and reducing its cost. Furthermore, it provides stable control, thus solving problems such as the high cost of permanent magnet bias magnetic levitation bearings and the high heat generation and short lifespan of existing electromagnetic magnetic levitation bearings.

[0009] In addition, the control device for the magnetic levitation bearing according to the above embodiments of the present invention may also have the following additional technical features:

[0010] According to one embodiment of the present invention, the position includes a radial position and an axial position. The bearing control unit is specifically used to: control the electromagnetic coil on the radial bearing to generate a radial control magnetic field according to the radial position, so that the rotor is in a target radial position under the combined action of the radial control magnetic field and the radial bias magnetic field generated by the constant current source coil on the radial bearing; and control the electromagnetic coil on the axial bearing to generate an axial control magnetic field according to the axial position, so that the rotor is in a target axial position under the combined action of the axial control magnetic field and the axial bias magnetic field generated by the constant current source coil on the axial bearing.

[0011] According to one embodiment of the present invention, the constant current source control unit includes a first constant current source circuit and a first constant current source controller, wherein the first constant current source circuit includes: a first switching transistor, the first terminal of which is connected to the first terminal of a DC power supply; a first diode, the cathode of which is connected to the second terminal of the first switching transistor and forms a first node, the anode of which is connected to the second terminal of the DC power supply, and the first node is connected to one end of a constant current source coil; a second switching transistor, the first terminal of which is connected to the second terminal of the DC power supply; and a second diode, the anode of which is connected to the second terminal of the second switching transistor and forms a second node, the cathode of which is connected to the first terminal of the DC power supply, and the second node is connected to the other end of the constant current source coil.

[0012] According to one embodiment of the present invention, a first constant current source controller is connected to the third terminal of a first switching transistor and a second switching transistor, respectively, for controlling the first switching transistor and the second switching transistor to conduct and provide current to the constant current source coil to generate a bias magnetic field.

[0013] According to another embodiment of the present invention, the constant current source control unit includes a second constant current source circuit and a second constant current source controller, wherein the second constant current source circuit includes: a third switching transistor, the first end of which is connected to the first end of a DC power supply; a fourth switching transistor, the first end of which is connected to the second end of the third switching transistor and forms a third node, the second end of which is connected to the second end of the DC power supply, and the third node is connected to one end of a constant current source coil; a fifth switching transistor, the first end of which is connected to the second end of the DC power supply; and a sixth switching transistor, the first end of which is connected to the second end of the fifth switching transistor and forms a fourth node, the second end of which is connected to the first end of the DC power supply, and the fourth node is connected to the other end of the constant current source coil.

[0014] According to one embodiment of the present invention, the second constant current source controller is connected to the third terminals of the third, fourth, fifth and sixth switching transistors respectively, and is used to control the third and fifth switching transistors to conduct, or to control the fourth and sixth switching transistors to conduct, so as to provide current to the constant current source coil to generate a bias magnetic field.

[0015] According to one embodiment of the present invention, the constant current source coil includes a first constant current source coil and a second constant current source coil disposed therebetween, the first constant current source coil and the second constant current source coil are connected in series, and the current supplied to the first constant current source coil and the second constant current source coil at the same time is in opposite directions.

[0016] According to one embodiment of the present invention, the bearing control unit includes a bearing control circuit and a bearing controller. The bearing control circuit includes: a seventh switch transistor, the first end of which is connected to the first end of a DC power supply; an eighth switch transistor, the first end of which is connected to the second end of the seventh switch transistor and forms a fifth node, the second end of which is connected to the second end of the DC power supply, and the fifth node is connected to one end of an electromagnetic coil; a ninth switch transistor, the first end of which is connected to the first end of the DC power supply; and a tenth switch transistor, the first end of which is connected to the second end of the ninth switch transistor and forms a sixth node, the second end of which is connected to the second end of the DC power supply, and the sixth node is connected to the other end of the electromagnetic coil.

[0017] According to one embodiment of the present invention, the bearing controller is connected to the third terminals of the seventh, eighth, ninth, and tenth switching transistors, respectively. When the bearing control circuit and the bearing controller are used to control the electromagnetic coil on the radial bearing to generate a radial control magnetic field based on the radial position, the bearing controller is configured to: control the seventh and tenth switching transistors to conduct when the radial position deviates from a first side towards the target radial position, providing a current in a first direction to the electromagnetic coil, so that the radial position moves towards the target radial position; and control the eighth and ninth switching transistors to conduct when the radial position deviates from a second side towards the target radial position, providing a current in a second direction to the electromagnetic coil, so that the radial position moves towards the target radial position, wherein the first side and the second side are opposite directions.

[0018] According to one embodiment of the present invention, the bearing controller is connected to the third terminals of the seventh, eighth, ninth, and tenth switching transistors, respectively. When the bearing control circuit and the bearing controller are used to control the electromagnetic coil on the axial bearing to generate an axial control magnetic field based on the axial position, the bearing controller is used to: control the seventh and tenth switching transistors to conduct when the axial position deviates from a first side towards the target axial position, providing a third-direction current to the electromagnetic coil to move the axial position towards the target axial position; and control the eighth and ninth switching transistors to conduct when the axial position deviates from a second side towards the target axial position, providing a fourth-direction current to the electromagnetic coil to move the axial position towards the target axial position, wherein the first side and the second side are opposite directions.

[0019] According to one embodiment of the present invention, the electromagnetic coil includes a first electromagnetic coil and a second electromagnetic coil disposed therebetween, the first electromagnetic coil and the second electromagnetic coil are connected in series, and the current supplied to the first electromagnetic coil and the second electromagnetic coil at the same time has the same direction.

[0020] To achieve the above objectives, a second aspect of the present invention provides a centrifugal compressor including the control device for the magnetic levitation bearing described above.

[0021] According to the centrifugal compressor of the present invention, the heat generation of the power drive component can be reduced by the control device of the magnetic levitation bearing described above, thereby extending the working life of the magnetic levitation bearing, reducing the cost of the magnetic levitation bearing, and ensuring stable control. This solves the problems of high cost of permanent magnet bias magnetic levitation bearings and high heat generation and short life of existing electromagnetic magnetic levitation bearings.

[0022] To achieve the above objectives, a second aspect of the present invention provides an electrical device including the control device for the magnetic levitation bearing described above, or the centrifugal compressor described above.

[0023] According to the electrical equipment of the present invention, the heat generated by the power drive component can be reduced by the control device or centrifugal compressor of the magnetic levitation bearing described above, thereby extending the working life of the magnetic levitation bearing, reducing the cost of the magnetic levitation bearing, and ensuring stable control. This solves the problems of high cost of permanent magnet bias magnetic levitation bearings and high heat generation and short life of existing electromagnetic magnetic levitation bearings.

[0024] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0025] Figure 1 This is a block diagram of a control device for a magnetic levitation bearing according to an embodiment of the present invention;

[0026] Figure 2 This is a schematic diagram of the structure of a magnetic levitation bearing according to an embodiment of the present invention;

[0027] Figure 3 This is a circuit topology diagram of a control device for a magnetic levitation bearing according to an embodiment of the present invention;

[0028] Figure 4 This is a circuit topology diagram of a control device for a magnetic levitation bearing according to another embodiment of the present invention;

[0029] Figure 5 This is a schematic diagram of the forces acting on a rotor according to an embodiment of the present invention;

[0030] Figure 6 This is a schematic diagram of the forces acting on a rotor according to another embodiment of the present invention;

[0031] Figure 7 This is a block diagram of a centrifugal compressor according to an embodiment of the present invention;

[0032] Figure 8 This is a block diagram of an electrical device according to an embodiment of the present invention;

[0033] Figure 9 This is a block diagram of an electrical device according to another embodiment of the present invention. Detailed Implementation

[0034] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0035] The control device, centrifugal compressor, and electrical equipment for the magnetic levitation bearing proposed in the embodiments of the present invention are described below with reference to the accompanying drawings.

[0036] Figure 1 This is a block diagram of a control device for a magnetic levitation bearing according to an embodiment of the present invention.

[0037] In some embodiments of the present invention, such as Figure 2 As shown, the magnetic levitation bearing 200 includes a rotor 210, a radial bearing 220 and an axial bearing 230 arranged around the rotor 210, and a constant current source coil 240 and an electromagnetic coil 250 are arranged on the radial bearing 220 and the axial bearing 230, respectively. The number of radial bearings 220 and axial bearings 230 can be specifically set according to the length of the rotor 210. Figure 2 In the illustrated magnetic levitation bearing, the radial bearing 220 includes a front radial bearing 221 and a rear radial bearing 222, and there are two axial bearings 230, which are respectively disposed outside the front radial bearing 221 and the rear radial bearing 222. For ease of understanding, the control device of the magnetic levitation bearing in this embodiment of the invention is illustrated by using a constant current source control unit and a bearing control unit corresponding to one axial bearing / radial bearing as examples.

[0038] like Figure 1 As shown, the control device 100 for the magnetic levitation bearing in this embodiment of the invention may include: a constant current source control unit 110 and a bearing control unit 120.

[0039] The constant current source control unit 110 is connected to the constant current source coil 240 and is used to control the constant current source coil 240 to generate a bias magnetic field. The bearing control unit 120 is connected to the electromagnetic coil 250 and is used to obtain the rotor's position and control the electromagnetic coil 250 to generate a control magnetic field based on the position, so that the rotor is at the target position under the combined action of the control magnetic field and the bias magnetic field. The target position is the bearing center position.

[0040] Specifically, such as Figure 1As shown, a DC power supply (DC) is connected to a constant current source control unit 110. The output current flows through the constant current source control unit 110 into a constant current source coil 240, causing the constant current source coil 240 to generate a bias magnetic field, thus keeping the rotor in a static equilibrium state. The DC power supply (DC) is also connected to a bearing control unit 120, which may include a displacement sensor to acquire the rotor's position. When the rotor's position shifts due to a disturbance, the bearing control unit 120 controls the DC power supply (DC) to output a current of appropriate magnitude and direction, which flows into the electromagnetic coil 250, generating a corresponding control magnetic field. The rotor experiences corresponding electromagnetic forces in the control magnetic field and the bias magnetic field. Under the combined action of these electromagnetic forces, the rotor moves towards the target position until it returns to the target position. During this process, the current flowing through the bearing control unit 120 is only the control current, and the electromagnetic coil 250 only provides the control flux. The small current reduces the heat generation of the electromagnetic coil 250 and the bearing control unit 120, ensuring long-term stable and reliable operation of both.

[0041] According to one embodiment of the present invention, the position includes a radial position and an axial position. The bearing control unit 120 is specifically configured to: control the electromagnetic coil 250 on the radial bearing to generate a radial control magnetic field according to the radial position, so that the rotor is in a target radial position under the combined action of the radial control magnetic field and the radial bias magnetic field generated by the constant current source coil 240 on the radial bearing; and control the electromagnetic coil 250 on the axial bearing to generate an axial control magnetic field according to the axial position, so that the rotor is in a target axial position under the combined action of the axial control magnetic field and the axial bias magnetic field generated by the constant current source coil 240 on the axial bearing.

[0042] Specifically, during operation, the bearing may experience radial and axial displacement. When the bearing control unit 120 detects a radial displacement, it controls the DC power supply to output a current of corresponding magnitude and direction, which flows through the electromagnetic coil 250 on the radial bearing to generate a corresponding radial control magnetic field. The rotor experiences corresponding electromagnetic forces in the radial control magnetic field and the radial bias magnetic field. Under the combined action of these electromagnetic forces, the rotor moves towards the target radial position until it returns to the target radial position. When the bearing control unit 120 detects an axial displacement, it controls the DC power supply to output a current of corresponding magnitude and direction, which flows through the electromagnetic coil 250 on the axial bearing to generate a corresponding axial control magnetic field. The rotor experiences corresponding electromagnetic forces in the axial control magnetic field and the axial bias magnetic field. Under the combined action of these electromagnetic forces, the rotor moves towards the target axial position until it returns to the target axial position.

[0043] According to one embodiment of the present invention, such as Figure 3 As shown, the constant current source control unit 110 includes a first constant current source circuit 111 and a first constant current source controller (not shown in the figure). The first constant current source circuit 111 includes: a first switching transistor Q1, the first end of which is connected to the first end of a DC power supply DC; a first diode D1, the cathode of which is connected to the second end of the first switching transistor Q1 and forms a first node, the anode of which is connected to the second end of the DC power supply DC, and the first node is connected to one end of a constant current source coil 240; a second switching transistor Q2, the first end of which is connected to the second end of the DC power supply DC; and a second diode D2, the anode of which is connected to the second end of the second switching transistor Q2 and forms a second node, the cathode of which is connected to the first end of the DC power supply DC, and the second node is connected to the other end of a constant current source coil 240.

[0044] Furthermore, according to one embodiment of the present invention, such as Figure 3 As shown, the first constant current source controller is connected to the third terminal of the first switch Q1 and the second switch Q2 respectively, and is used to control the first switch Q1 and the second switch Q2 to conduct and provide current to the constant current source coil 240 to generate a bias magnetic field.

[0045] Furthermore, according to one embodiment of the present invention, such as Figure 3 As shown, the constant current source coil 240 includes a first constant current source coil 241 and a second constant current source coil 242, which are connected in series. At the same time, the currents supplied to the first constant current source coil 241 and the second constant current source coil 242 are in opposite directions. The first constant current source coil 241 and the second constant current source coil 242 can be respectively disposed on opposite sides of the rotor; for example, the first constant current source coil 241 can be disposed above the rotor, and the second constant current source coil 242 can be disposed below the rotor.

[0046] Specifically, such as Figure 3As shown, when the first constant current source controller turns on the first switch Q1 and the second switch Q2, the current output from the positive terminal of the DC power supply flows sequentially through the first switch Q1 to the first constant current source coil 241 and the second constant current source coil 242, and then through the second switch Q2 to the negative terminal of the DC power supply. A circuit is formed connecting the positive terminal of the DC power supply, the first switch Q1, the first constant current source coil 241, the second constant current source coil 242, the second switch Q2, and the negative terminal of the DC power supply. At this time, the current direction of the first constant current source coil 241 is from left to right, and the current direction of the second constant current source coil 242 is from right to left, with the current directions of the first constant current source coil 241 and the second constant current source coil 242 being opposite. According to the law of electromagnetic induction, the first constant current source coil 241 and the second constant current source coil 242 generate fixed and opposite bias magnetic fluxes, thereby generating electromagnetic forces of the same magnitude but opposite bias directions, keeping the rotor in a static equilibrium state.

[0047] According to another embodiment of the invention, such as Figure 4 As shown, the constant current source control unit 110 includes a second constant current source circuit 112 and a second constant current source controller (not shown in the figure). The second constant current source circuit 112 includes: a third switch Q3, the first end of which is connected to the first end of a DC power supply DC; a fourth switch Q4, the first end of which is connected to the second end of the third switch Q3 and forms a third node, the second end of which is connected to the second end of the DC power supply DC, and the third node is connected to one end of the constant current source coil 240; a fifth switch Q5, the first end of which is connected to the second end of the DC power supply DC; and a sixth switch Q6, the first end of which is connected to the second end of the fifth switch Q5 and forms a fourth node, the second end of which is connected to the first end of the DC power supply DC, and the fourth node is connected to the other end of the constant current source coil 240.

[0048] Furthermore, according to one embodiment of the present invention, such as Figure 4 As shown, the second constant current source controller is connected to the third terminals of the third switch Q3, the fourth switch Q4, the fifth switch Q5, and the sixth switch Q6, respectively, to control the third switch Q3 and the fifth switch Q5 to conduct, or to control the fourth switch Q4 and the sixth switch Q6 to conduct, so as to provide current to the constant current source coil 240 to generate a bias magnetic field.

[0049] Furthermore, according to one embodiment of the present invention, such as Figure 4As shown, the constant current source coil 240 includes a first constant current source coil 241 and a second constant current source coil 242, which are connected in series. At the same time, the currents supplied to the first constant current source coil 241 and the second constant current source coil 242 are in opposite directions. The first constant current source coil 241 and the second constant current source coil 242 can be respectively disposed on opposite sides of the rotor; for example, the first constant current source coil 241 can be disposed above the rotor, and the second constant current source coil 242 can be disposed below the rotor.

[0050] Specifically, such as Figure 4 As shown, when the second constant current source controller turns on the third switch Q3 and the fifth switch Q5, and turns off the fourth switch Q4 and the sixth switch Q6, the current output from the positive terminal of the DC power supply flows sequentially through the third switch Q3 to the first constant current source coil 241 and the second constant current source coil 242, and then through the fifth switch Q5 to the negative terminal of the DC power supply. A circuit is formed consisting of the positive terminal of the DC power supply, the third switch Q3, the first constant current source coil 241, the second constant current source coil 242, the fifth switch Q5, and the negative terminal of the DC power supply. At this time, the current direction of the first constant current source coil 241 is from left to right, and the current direction of the second constant current source coil 242 is from right to left; the current directions of the first constant current source coil 241 and the second constant current source coil 242 are opposite. According to the law of electromagnetic induction, the first constant current source coil 241 and the second constant current source coil 242 generate fixed bias magnetic fluxes with opposite directions, thereby generating electromagnetic forces of the same magnitude but opposite bias directions, so that the rotor is in a static equilibrium state.

[0051] When the second constant current source controller turns on the fourth switch Q4 and the sixth switch Q6, and turns off the third switch Q3 and the fifth switch Q5, the current output from the positive terminal of the DC power supply flows sequentially through the sixth switch Q6 to the second constant current source coil 242, the first constant current source coil 241, and then through the fourth switch Q4 to the negative terminal of the DC power supply. A circuit is formed connecting the positive terminal of the DC power supply, the sixth switch Q6, the second constant current source coil 242, the first constant current source coil 241, the fourth switch Q4, and the negative terminal of the DC power supply. At this time, the current direction of the first constant current source coil 241 is from right to left, and the current direction of the second constant current source coil 242 is from left to right, with the current directions of the first and second constant current source coils being opposite. According to the law of electromagnetic induction, the first and second constant current source coils 241 and 242 generate fixed and opposite bias magnetic fluxes, thereby generating electromagnetic forces of the same magnitude but opposite bias directions, keeping the rotor in a static equilibrium state.

[0052] According to one embodiment of the present invention, such as Figure 3 and Figure 4As shown, the bearing control unit 120 includes a bearing control circuit 121 and a bearing controller (not shown in the figure). The bearing control circuit 121 includes: a seventh switch Q7, the first end of which is connected to the first end of a DC power supply DC; an eighth switch Q8, the first end of which is connected to the second end of the seventh switch Q7 and forms a fifth node, the second end of which is connected to the second end of the DC power supply DC, and the fifth node is connected to one end of an electromagnetic coil 250; a ninth switch Q9, the first end of which is connected to the first end of a DC power supply DC; and a tenth switch Q10, the first end of which is connected to the second end of the ninth switch Q9 and forms a sixth node, the second end of which is connected to the second end of the DC power supply DC, and the sixth node is connected to the other end of an electromagnetic coil 250.

[0053] According to one embodiment of the present invention, such as Figure 3 and Figure 4 As shown, the bearing controller is connected to the third terminals of the seventh switch Q7, the eighth switch Q8, the ninth switch Q9, and the tenth switch Q10, respectively. When the bearing control circuit 121 and the bearing controller are used to control the electromagnetic coil 250 on the radial bearing to generate a radial control magnetic field based on the radial position, the bearing controller is used to: control the seventh switch Q7 and the tenth switch Q10 to conduct when the radial position deviates from the first side of the target radial position, providing a current in the first direction to the electromagnetic coil 250, so that the radial position moves towards the target radial position; and control the eighth switch Q8 and the ninth switch Q9 to conduct when the radial position deviates from the second side of the target radial position, providing a current in the second direction to the electromagnetic coil 250, so that the radial position moves towards the target radial position. The first side and the second side are opposite directions. For example, when the radial direction is vertical, the first side of the target radial position is below the target radial position, and the second side of the target radial position is above the target radial position. The first direction and the second direction are opposite. Figure 3 and Figure 4 The first direction shows the current direction from left to right, and the second direction shows the current direction from right to left.

[0054] Specifically, the electromagnetic coil 250 on the radial bearing is controlled by an H-bridge consisting of the seventh switch Q7, the eighth switch Q8, the ninth switch Q9, and the tenth switch Q10. Current can flow bidirectionally through the electromagnetic coil 250 on the radial bearing. The bearing controller can detect the rotor's position. When the magnetic levitation bearing is operating normally, the rotor is in its equilibrium position, i.e., the target radial position. When the magnetic levitation bearing is disturbed, the rotor will deviate from the target radial position. When the bearing controller detects that the rotor's radial position has deviated from the first side of the target radial position, i.e., it is lower than the target radial position, the bearing controller controls the seventh switch Q7 and the tenth switch Q10 to turn on, and the eighth switch Q8 and the ninth switch Q9 to turn off. The current flows from the positive terminal of the DC power supply through the seventh switch Q7 into the electromagnetic coil 250, and through the tenth switch Q10 to the negative terminal of the DC power supply. The positive terminal of the DC power supply, the seventh switch Q7, the electromagnetic coil 250, the tenth switch Q10, and the negative terminal of the DC power supply form a circuit. At this time, the current in the electromagnetic coil 250 is from left to right, generating an upward electromagnetic force, causing the rotor to move upward until the rotor's radial position rises to the target radial position. When the bearing controller detects that the rotor's radial position deviates from the second side of the target radial position, i.e., it is higher than the target radial position, the bearing controller controls the eighth switch Q8 and the ninth switch Q9 to turn on, and the seventh switch Q7 and the tenth switch Q10 to turn off. The current flows from the positive terminal of the DC power supply through the ninth switch Q9 into the electromagnetic coil 250, and then through the eighth switch Q8 to the negative terminal of the DC power supply. The positive terminal of the DC power supply, the ninth switch Q9, the electromagnetic coil 250, the eighth switch Q8, and the negative terminal of the DC power supply form a circuit. At this time, the current in the electromagnetic coil 250 is from right to left, generating a downward electromagnetic force, causing the rotor to move downward until the rotor's radial position is lowered to the target radial position.

[0055] According to another embodiment of the invention, such as Figure 3 and Figure 4As shown, the bearing controller is connected to the third terminals of the seventh switch Q7, the eighth switch Q8, the ninth switch Q9, and the tenth switch Q10, respectively. When the bearing control circuit 121 and the bearing controller are used to control the electromagnetic coil 250 on the axial bearing to generate an axial control magnetic field based on the axial position, the bearing controller is used to: control the seventh switch Q7 and the tenth switch Q10 to conduct when the axial position deviates from the first side of the target axial position, providing a third-direction current to the electromagnetic coil to move the axial position towards the target axial position; and control the eighth switch Q8 and the ninth switch Q9 to conduct when the axial position deviates from the second side of the target axial position, providing a fourth-direction current to the electromagnetic coil to move the axial position towards the target axial position. The first side and the second side are opposite directions. For example, when the axial direction is horizontal, the first side of the target axial position is the left side of the target axial position, and the second side of the target axial position is the right side of the target axial position. The third direction is opposite to the fourth direction. Figure 3 and Figure 4 The fourth direction shows the current direction from left to right.

[0056] Specifically, the electromagnetic coil 250 on the axial bearing is controlled by an H-bridge consisting of the seventh switch Q7, the eighth switch Q8, the ninth switch Q9, and the tenth switch Q10. Current can flow bidirectionally through the electromagnetic coil 250 on the axial bearing. The bearing controller can detect the rotor's position. When the magnetic levitation bearing is operating normally, the rotor is in its equilibrium position, i.e., the target axial position. When the magnetic levitation bearing is disturbed, the rotor will deviate from the target axial position. When the bearing controller detects that the rotor's axial position has deviated from the first side of the target axial position, i.e., to the left of the target axial position, the bearing controller controls the seventh switch Q7 and the tenth switch Q10 to turn on, and the eighth switch Q8 and the ninth switch Q9 to turn off. Current flows from the positive terminal of the DC power supply through the seventh switch Q7 into the electromagnetic coil 250, and through the tenth switch Q10 to the negative terminal of the DC power supply. The positive terminal of the DC power supply, the seventh switch Q7, the electromagnetic coil 250, the tenth switch Q10, and the negative terminal of the DC power supply form a circuit. At this time, the current in the electromagnetic coil 250 is from left to right, generating an electromagnetic force to the right, causing the rotor to move to the right until the rotor's axial position returns to the target axial position. When the bearing controller detects that the rotor's axial position has deviated to the second side of the target axial position, i.e., to the right of the target axial position, the bearing controller controls the eighth switch Q8 and the ninth switch Q9 to turn on, and the seventh switch Q7 and the tenth switch Q10 to turn off. Current flows from the positive terminal of the DC power supply through the ninth switch Q9 into the electromagnetic coil 250, and then through the eighth switch Q8 to the negative terminal of the DC power supply. The positive terminal of the DC power supply, the ninth switch Q9, the electromagnetic coil 250, the eighth switch Q8, and the negative terminal of the DC power supply form a circuit. At this time, the current in the electromagnetic coil 250 is from right to left, generating an electromagnetic force to the left, causing the rotor to move to the left until the rotor's axial position returns to the target axial position.

[0057] According to one embodiment of the present invention, such as Figure 3 and Figure 4 As shown, the electromagnetic coil 250 includes a first electromagnetic coil 251 and a second electromagnetic coil 252, which are connected in series and supplied with current in the same direction at the same time. The first electromagnetic coil 251 and the second electromagnetic coil 252 can be wound around a pair of magnetic poles above and below the rotor, respectively. The electromagnetic coil 250 on the radial bearing will be described below.

[0058] Specifically, when the bearing controller detects that the rotor's radial position is lower than the target radial position, such as... Figure 5As shown, when the rotor is below the center of the bearing (d1 < d2), the bearing controller controls the seventh switch tube Q7 and the tenth switch tube Q10 to conduct, and the eighth switch tube Q8 and the ninth switch tube Q9 to turn off. The current flows from the positive pole of the DC power supply DC through the seventh switch tube Q7 into the electromagnetic coil 250, and through the tenth switch tube Q10 to the negative pole of the DC power supply DC. The positive pole of the DC power supply DC, the seventh switch tube Q7, the electromagnetic coil 250, the tenth switch tube Q10, and the negative pole of the DC power supply DC form a loop. At this time, the direction of the current i1 in the first electromagnetic coil 251 and the second electromagnetic coil 252 is from left to right, as Figure 5 shown. The current i1 of the left bearing control unit 120 flows into the electromagnetic coil 250. The electromagnetic force F1 generated by the first electromagnetic coil 251 (the upper half of the electromagnetic coil 250) is upward, and the electromagnetic force F1' generated by the second electromagnetic coil 252 (the lower half of the electromagnetic coil 250) is also upward. The current i0 of the right constant current source unit flows into the constant current source coil 240. The electromagnetic force F0 generated by the first constant current source coil 241 (the upper half of the constant current source coil 240) is upward, and the electromagnetic force F0' generated by the second constant current source coil 242 (the lower half of the constant current source coil 240) is downward. At this time, the force formula on the rotor is: F0 + F1 + F1' > F0' + mg, where mg is the gravity of the rotor. The upward electromagnetic force is greater than the downward electromagnetic force and the gravity of the rotor, and the rotor slowly moves upward until it moves to the center position of the bearing, that is, the target radial position.

[0059] When the bearing controller detects that the radial position of the rotor is higher than the target radial position, as Figure 6 shown, that is, when the rotor is above the center of the bearing (d1 > d2), the bearing controller controls the eighth switch tube Q8 and the ninth switch tube Q9 to conduct, and the seventh switch tube Q7 and the tenth switch tube Q10 to turn off. The current flows from the positive pole of the DC power supply DC through the ninth switch tube Q9 into the electromagnetic coil 250, and through the eighth switch tube Q8 to the negative pole of the DC power supply DC. The positive pole of the DC power supply DC, the ninth switch tube Q9, the electromagnetic coil 250, the eighth switch tube Q8, and the negative pole of the DC power supply DC form a loop. At this time, the direction of the current i1 in the first electromagnetic coil 251 and the second electromagnetic coil 252 is from right to left, as Figure 6As shown in the figure, the current i1 of the left bearing control unit 120 flows out of the electromagnetic coil 250. The electromagnetic force F1 generated by the first electromagnetic coil 251 (the upper half of the electromagnetic coil 250) is downward, and the electromagnetic force F1' generated by the second electromagnetic coil 252 (the lower half of the electromagnetic coil 250) is also downward. The current i0 of the right constant current source unit flows into the constant current source coil 240. The electromagnetic force F0 generated by the first constant current source coil 241 (the upper half of the constant current source coil 240) is upward, and the electromagnetic force F0' generated by the second constant current source coil 242 (the lower half of the constant current source coil 240) is downward. At this time, the force formula of the rotor is: F0 < F1 + F1' + F0' + mg. The upward electromagnetic force is less than the downward electromagnetic force and the gravity of the rotor, and the rotor slowly moves downward until it moves to the center position of the bearing, that is, the target radial position.

[0060] It should be noted that in the above embodiments, for the sake of convenience of description, the control device of the magnetic levitation bearing is only exemplified by a constant current source control unit and a bearing control unit corresponding to one axial bearing / radial bearing. When the number of axial bearings / radial bearings is multiple, the circuit is also arranged according to the above. In summary, according to the control device of the magnetic levitation bearing in the embodiments of the present invention, the constant current source control unit controls the constant current source coil to generate a bias magnetic field, and the bearing control unit obtains the position of the rotor and controls the electromagnetic coil to generate a control magnetic field according to the position, so that the rotor is in the target position under the joint action of the control magnetic field and the bias magnetic field. Thus, the device can reduce the heat generation of the power drive component, thereby extending the working life of the magnetic levitation bearing, and can reduce the cost of the magnetic levitation bearing, and the control is stable, so as to solve the problems of high cost of the permanent magnet biased magnetic levitation bearing, large heat generation and low life of the existing electromagnetic magnetic levitation bearing, etc.

[0061] Corresponding to the above embodiments, the present invention also proposes a centrifugal compressor.

[0062] Figure 7 It is a block diagram of the centrifugal compressor according to the embodiment of the present invention.

[0063] As Figure 7 shown, the centrifugal compressor 300 according to the embodiment of the present invention includes the control device 100 of the magnetic levitation bearing described above.

[0064] According to the centrifugal compressor of the embodiment of the present invention, through the above control device of the magnetic levitation bearing, the heat generation of the power drive component can be reduced, thereby extending the working life of the magnetic levitation bearing, and the cost of the magnetic levitation bearing can be reduced, and the control is stable, so as to solve the problems of high cost of the permanent magnet biased magnetic levitation bearing, large heat generation and low life of the existing electromagnetic magnetic levitation bearing, etc.

[0065] Corresponding to the above embodiments, the present invention also proposes an electrical equipment.

[0066] According to one embodiment of the present invention, such as Figure 8 As shown, the electrical device 400 of this embodiment includes the control device 100 for the magnetic levitation bearing described above.

[0067] According to another embodiment of the invention, such as Figure 9 As shown, the electrical device 400 of this embodiment includes the centrifugal compressor 300 described above.

[0068] According to the electrical equipment of the present invention, the heat generated by the power drive component can be reduced by the control device or centrifugal compressor of the magnetic levitation bearing described above, thereby extending the working life of the magnetic levitation bearing, reducing the cost of the magnetic levitation bearing, and ensuring stable control. This solves the problems of high cost of permanent magnet bias magnetic levitation bearings and high heat generation and short life of existing electromagnetic magnetic levitation bearings.

[0069] It should be noted that the logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as a sequenced list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by, or in conjunction with, an instruction execution system, apparatus, or device (such as a computer-based system, a processor-included system, or other system that can fetch and execute instructions from, an instruction execution system, apparatus, or device). For the purposes of this specification, "computer-readable medium" can be any means that can contain, store, communicate, propagate, or transmit programs for use by, or in conjunction with, an instruction execution system, apparatus, or device. More specific examples (a non-exhaustive list) of computer-readable media include: an electrical connection having one or more wires (electronic device), a portable computer disk drive (magnetic device), random access memory (RAM), read-only memory (ROM), erasable and editable read-only memory (EPROM or flash memory), fiber optic devices, and portable optical disc read-only memory (CDROM). Alternatively, the computer-readable medium may be paper or other suitable media on which the program can be printed, since the program can be obtained electronically, for example, by optically scanning the paper or other medium, followed by editing, interpreting, or otherwise processing as necessary, and then stored in a computer memory.

[0070] It should be understood that various parts of the present invention can be implemented in hardware, software, firmware, or a combination thereof. In the above embodiments, multiple steps or methods can be implemented in software or firmware stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, it can be implemented using any one or a combination of the following techniques known in the art: discrete logic circuits having logic gates for implementing logical functions on data signals, application-specific integrated circuits (ASICs) having suitable combinational logic gates, programmable gate arrays (PGAs), field-programmable gate arrays (FPGAs), etc.

[0071] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0072] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0073] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0074] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A control device for a magnetic levitation bearing, characterized in that, The magnetic levitation bearing includes a rotor, a radial bearing and an axial bearing arranged around the rotor, and a constant current source coil and an electromagnetic coil are arranged on the radial bearing and the axial bearing. The control device includes: A constant current source control unit is connected to the constant current source coil and is used to control the constant current source coil to generate a bias magnetic field. The constant current source control unit includes a first constant current source circuit and a first constant current source controller. The first constant current source circuit includes: a first switching transistor, the first terminal of which is connected to the first terminal of a DC power supply; a first diode, the cathode of which is connected to the second terminal of the first switching transistor and forms a first node, the anode of which is connected to the second terminal of the DC power supply, and the first node is connected to one end of the constant current source coil; a second switching transistor, the first terminal of which is connected to the second terminal of the DC power supply; and a second diode, the anode of which is connected to the second terminal of the second switching transistor and forms a second node, the cathode of which is connected to the first terminal of the DC power supply, and the second node is connected to the other end of the constant current source coil. The first constant current source controller is connected to the third terminals of the first switching transistor and the second switching transistor respectively, and is used to control the first switching transistor and the second switching transistor to conduct and provide current to the constant current source coil to generate the bias magnetic field. A bearing control unit, which is connected to the electromagnetic coil, is used to obtain the position of the rotor and control the electromagnetic coil to generate a control magnetic field according to the position, so that the rotor is in the target position under the combined action of the control magnetic field and the bias magnetic field. The constant current source coil includes a first constant current source coil and a second constant current source coil, which are connected in series. At the same time, the current supplied to the first constant current source coil and the second constant current source coil are in opposite directions. The first constant current source coil and the second constant current source coil generate fixed and opposite bias magnetic flux, thereby generating electromagnetic forces of the same magnitude but opposite bias directions, so that the rotor is in a static equilibrium state. When the rotor deviates from the first side of the target position, the electromagnetic coil generates a control force in the direction of the target position on the first side of the rotor, and also generates a control force in the direction of the target position on the second side of the rotor, wherein the first side and the second side are two sides with opposite directions.

2. The apparatus according to claim 1, characterized in that, The position includes radial position and axial position, and the bearing control unit is specifically used for: The radial control magnetic field is generated by the electromagnetic coil on the radial bearing according to the radial position, so that the rotor is at the target radial position under the combined action of the radial control magnetic field and the radial bias magnetic field generated by the constant current source coil on the radial bearing. The electromagnetic coil on the axial bearing is controlled to generate an axial control magnetic field according to the axial position, so that the rotor is in the target axial position under the combined action of the axial control magnetic field and the axial bias magnetic field generated by the constant current source coil on the axial bearing.

3. The apparatus according to claim 1, characterized in that, The constant current source control unit includes a second constant current source circuit and a second constant current source controller, wherein the second constant current source circuit includes: The third switching transistor, wherein the first terminal of the third switching transistor is connected to the first terminal of the DC power supply; The fourth switch has a first end connected to the second end of the third switch and forms a third node. The second end of the fourth switch is connected to the second end of the DC power supply, and the third node is connected to one end of the constant current source coil. The fifth switching transistor, wherein the first terminal of the fifth switching transistor is connected to the second terminal of the DC power supply; The sixth switch has its first end connected to the second end of the fifth switch and forming a fourth node. The second end of the sixth switch is connected to the first end of the DC power supply, and the fourth node is connected to the other end of the constant current source coil.

4. The apparatus according to claim 3, characterized in that, The second constant current source controller is connected to the third terminal of the third, fourth, fifth and sixth switching transistors respectively, and is used to control the third and fifth switching transistors to conduct, or to control the fourth and sixth switching transistors to conduct, so as to provide current to the constant current source coil to generate the bias magnetic field.

5. The apparatus according to claim 2, characterized in that, The bearing control unit includes a bearing control circuit and a bearing controller, wherein the bearing control circuit includes: The seventh switch is connected at its first terminal to the first terminal of the DC power supply. The eighth switch has a first end connected to the second end of the seventh switch and forms a fifth node. The second end of the eighth switch is connected to the second end of the DC power supply, and the fifth node is connected to one end of the electromagnetic coil. The ninth switching transistor, the first terminal of which is connected to the first terminal of the DC power supply; The tenth switch has its first end connected to the second end of the ninth switch and forming a sixth node. The second end of the tenth switch is connected to the second end of the DC power supply, and the sixth node is connected to the other end of the electromagnetic coil.

6. The apparatus according to claim 5, characterized in that, The bearing controller is connected to the third terminals of the seventh, eighth, ninth, and tenth switching transistors, respectively. When the bearing control circuit and the bearing controller are used to control the electromagnetic coil on the radial bearing to generate a radial control magnetic field based on the radial position, the bearing controller is used to: When the radial position deviates from the first side of the target radial position, the seventh switch and the tenth switch are turned on to provide current in the first direction to the electromagnetic coil, so that the radial position moves toward the target radial position; When the radial position deviates from the second side of the target radial position, the eighth switch and the ninth switch are controlled to be turned on to provide the electromagnetic coil with a current in the second direction, so that the radial position moves toward the target radial position, wherein the first side and the second side are two sides with opposite directions.

7. The apparatus according to claim 5, characterized in that, The bearing controller is connected to the third terminals of the seventh, eighth, ninth, and tenth switching transistors, respectively. When the bearing control circuit and the bearing controller are used to control the electromagnetic coil on the axial bearing to generate an axial control magnetic field based on the axial position, the bearing controller is used to: When the axial position deviates from the first side of the target axial position, the seventh switch and the tenth switch are turned on to provide a third-direction current to the electromagnetic coil, so that the axial position moves toward the target axial position; When the axial position deviates from the second side of the target axial position, the eighth switch and the ninth switch are controlled to be turned on to provide the electromagnetic coil with a current in the fourth direction, so that the axial position moves toward the target axial position, wherein the first side and the second side are two sides with opposite directions.

8. The apparatus according to claim 6 or 7, characterized in that, The electromagnetic coil includes a first electromagnetic coil and a second electromagnetic coil that are respectively arranged in series, and the current supplied to the first electromagnetic coil and the second electromagnetic coil at the same time is in the same direction.

9. A centrifugal compressor, characterized in that, Includes the control device for the magnetic levitation bearing according to any one of claims 1-8.

10. An electrical appliance, characterized in that, Includes the control device for the magnetic levitation bearing according to any one of claims 1-8, or the centrifugal compressor according to claim 9.

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