JP2003293980A - Magnetic bearing type turbo molecular pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnetic bearing type turbo molecular pump wherein a type of a pump body and a power supply device automatically meet each other. <P>SOLUTION: A magnetic bearing control circuit 9 and a motor driving parameter storage means 10 are installed in an integral magnetic bearing control part 13, and parameters specific to types are transmitted from a motor driving parameter storage means 10 to the inverter control circuit 7 of the power supply 2 through the magnetic bearing control circuit 9 when the pump body 8 and the power supply 2 are operated in combination with each other to control the switching phase of the switching elements of a three-phase inverter 5 so as to supply a high frequency output to a motor stator 27a at a drive output matching the specifications of the pump body 8. Thus a motor rotor 27b is driven at a specified rotational speed. <P>COPYRIGHT: (C)2004,JPO

Description

Description: BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to a turbo molecular pump used as an exhaust system of a manufacturing apparatus or the like that requires a high vacuum. The present invention relates to a magnetic bearing type turbo-molecular pump provided with the same. 2. Description of the Related Art There is a turbo molecular pump as a vacuum pump for transporting a gas by mechanically giving a momentum in a certain direction to a gas molecule by a rotary wing or the like. A turbo-molecular pump has a rotating blade with an oblique slit in a disk and a shape almost the same as that of the rotating blade under low-pressure conditions where collisions between gas molecules can be ignored. The rotating blades are driven at an extremely high rotational speed, gas molecules pass through the gap between the two blades, and are evacuated to a vacuum to obtain an ultra-high vacuum. It is. An oil rotary pump, a mechanical booster pump, a dry vacuum pump, or the like is used as a back pressure pump in a vacuum evacuation system of the turbo molecular pump. FIG. 2 shows a cross section of a magnetic bearing type turbo-molecular pump provided with a magnetic bearing device. The turbo-molecular pump has a drive shaft 28 provided with a radial protection bearing 17 on the upper side and a thrust radial protection bearing 25 on the lower side, a magnetic levitation mechanism, and a high-frequency driven motor stator 27a.
And high speed rotation (for example, 20
In the upper part of the drive shaft 28, the rotating body is provided with the rotating blade body 16, and the fixed blade 30 stacked with the spacer 29 is provided on the housing side opposite to the rotating body, so that the rotating blade body 16 can operate at high speed. By rotating, the gas is sucked from the intake port 14 through the protection net 15, and the gas sucked from the exhaust port 26 at the lower part of the housing is discharged. Since the rotor 16 rotates at a high speed, magnetic levitation control for supporting the rotor of the drive shaft 28 in a non-contact manner is performed. As a set of axial direction control electromagnets for controlling the position of the drive shaft 28 in the direction, the thrust magnetic bearing 23
The radial magnetic bearing 19 and the radial magnetic bearing 21 are provided as two sets of radial direction control electromagnets that perform position control in two directions orthogonal to each other at two points on the drive shaft 28.
Is provided. The sensor 2 is used as a sensor for detecting an axial direction as a sensor for detecting displacement of the drive shaft 28.
4 are provided, and a sensor 18 and a sensor 22 are provided as radial direction detection sensors. A power supply terminal 20 is provided on a side surface of the housing as a terminal for supplying power to these components. FIG. 3 shows a control block circuit of a conventional magnetic bearing type turbo molecular pump. A magnetic bearing control circuit 9a for causing magnetic levitation is housed in the integrated magnetic bearing control unit 13a, attached to the pump body 8a, and performs feedback control. The magnetic bearing control circuit 9a includes:
Output displacement signals from the sensors 18 and 22 for radial detection are compared with a reference signal of a target value for position control. The deviation is converted into a PID control signal by a signal processing system of the magnetic bearing control circuit 9a, and an excitation current is supplied to the radial magnetic bearings 19 and 21 of the control electromagnet via a power amplifier to thereby drive the drive shaft 28. The drive shaft 28 is attracted to each other by the radial magnetic bearings 19 and 21 of the respective electromagnets disposed to face each other with the sandwiched therebetween, and the drive shaft 28 is controlled to an appropriate position, thereby performing magnetic levitation control. Also,
The output displacement signal from the sensor 24 for detecting the axial direction is compared with a reference signal of a target value of the flying position control, and the deviation thereof is determined by a signal processing system of the magnetic bearing control circuit 9a.
The control signal is converted into a D control signal, and an exciting current is supplied to the thrust magnetic bearing 23 of the control electromagnet through a power amplifier to control the vertical position, thereby performing magnetic levitation control. On the other hand, the drive shaft 2 that rotates at a high speed as described above
8 is provided with protective bearings (radial thrusts) 17 and 25 for holding the rotating body when the rotation speed becomes low or the rotation stops. This protective bearing 1
Reference numerals 7 and 25 support the rotating body when the magnetic bearing does not function normally, such as when the cable is dropped due to an erroneous operation during high-speed rotation. The pump body 8a has a plurality of pumps having different sizes due to the difference in the pumping speed. When the pump body 8a is combined with the power supply device 2a, the type of the pump can be automatically determined. The main body 8a is provided with a model determining means 12. [0005] In the power supply device 2a, an AC voltage from the AC power supply 1 is converted into a DC voltage by an AC / DC converter 3 and input to a three-phase inverter 5 via a rectifier 4. The model signal from the model discriminating means 12 of the pump body 8a, or the model signal from the model setting means 11 set by the operator, and the motor driving parameter storage means 1
The model parameter signal from 0a is input to the inverter control circuit 7. The inverter control circuit 7 controls the high-frequency output by controlling the switching phase difference of the switching elements of the three-phase inverter 5, and rotates the high-frequency motor as specified. A conventional magnetic bearing type turbo-molecular pump comprises a pump main body 8a, an integrated magnetic bearing control section 13a and a power supply 2a as described above. Pump body 8a of a pump type turbo molecular pump
There are many types of pumps having different sizes depending on the pumping speed. On the other hand, the power supply device 2a has a motor to be controlled common to several types of pump bodies 8a, and the internal structure is almost the same. Nevertheless, due to differences in motor driving parameters such as rotation speed, acceleration time, and motor current limiter, there is a problem that a dedicated power supply device 2a must be prepared for each type of pump body 8a. is there. In addition, motor drive parameters are stored in advance for several types of pump bodies 8a assumed in advance, and the model is set by an operator, or the type of the connected pump bodies 8a is automatically set. The method for making a judgment is used to correspond to different types of pump main bodies 8a. Therefore, for each type of pump body 8a,
In the dedicated type power supply device 2a, it is necessary to prepare several types of power supply devices 2a having almost the same structure only by differences in motor driving parameters. Even if the operator sets the model or automatically determines the model, when a new type of pump body 8a is developed, the parameters for the new model are stored in the conventional power supply device 2a. There was no need to update software. [0007] The present invention has been made in view of such circumstances, and it is possible that the model of the pump main body and the power supply device automatically correspond without using the model setting by the operator or the model determining means of the pump main body. An object of the present invention is to provide a magnetic bearing type turbo-molecular pump that can be used. In order to achieve the above object, a magnetic bearing type turbo molecular pump according to the present invention comprises a pump body having a magnetic bearing type motor and an inverter for driving the motor at high frequency. A magnetic bearing type turbo-molecular pump that rotates a rotor blade at high speed and exhausts gas molecules by using a power supply device having a power supply and an integrated magnetic bearing control unit mounted on a pump body. A storage unit for storing circuit and model-specific motor driving parameters, and transmitting the motor driving parameters from the storage unit to the inverter control circuit in the power supply device via the magnetic bearing control circuit to control the inverter, and Is designed to rotate at high speed. The magnetic bearing type turbo-molecular pump of the present invention is constructed as described above. The pump body is provided with an integrated magnetic bearing control section, and the integrated magnetic bearing control section has a magnetic bearing control circuit and a model specific model. Storage means for storing the motor drive parameters of the three-phase inverter, and sends the model-specific parameters from the motor drive parameter storage means to the inverter control circuit provided in the power supply device via the magnetic bearing control circuit. The high frequency output is controlled, and the high frequency motor of the pump body rotates at high speed as specified. Thereby, the power supply device automatically corresponds to the pump body. In addition, by adding this automatic correspondence function to a newly developed pump body, it is possible to respond in the future without changing the software of the power supply device. Further, it is not necessary to manufacture a power supply device for each type of the pump main body, and it is possible to reduce product inventory. An embodiment of the magnetic bearing type turbo-molecular pump according to the present invention will be described with reference to FIG. FIG.
FIG. 2 is a diagram showing a control circuit of the magnetic bearing type turbo-molecular pump of the present invention. The magnetic bearing type turbo molecular pump includes a pump body 8, an integrated magnetic bearing control unit 13, and a power supply device 2. The function and operation of each unit will be described below. As shown in FIG. 2, the pump body 8 is
A rotary wing body 16 is provided on the upper part of the bearing, and a protective bearing 17 (radial) provided on the upper part and a protective bearing 2 provided on the lower part are provided.
5 (thrust radial), and a three-phase high-frequency current from the power supply device 2 flows through a motor stator 27a of a high-frequency motor provided in the center portion, thereby
7b is rotated at high speed. When the rotary wing body 16 rotates at a high speed, gas is sucked from the intake port 14 through the protection net 15, and the gas sucked from the exhaust port 26 at the lower portion of the housing is discharged. This magnetic bearing type turbo molecular pump
Magnetic levitation control for supporting the rotating body of the drive shaft 28 in a non-contact manner is performed so that the rotating wing body 16 can rotate at high speed.
A radial magnetic bearing 19 is provided above the drive shaft 28, a radial magnetic bearing 21 is provided below the drive shaft 28, and a thrust magnetic bearing 23 is provided at the lowermost portion. The rotor 16 is magnetically levitated and rotates at a high speed, and an intake port provided at the upper portion The gas is sucked from 14 and exhausted from an exhaust port 26 provided at the lower part. And the drive shaft 28
The rotation speed and the degree of eccentricity of the
And a sensor 22 provided at the lower portion, and a vertical floating state is detected by a sensor 24 provided at the lowermost portion. The signal is input to the magnetic bearing control circuit 9. The integrated magnetic bearing control section 13 comprises a magnetic bearing control circuit 9 integrated with the pump body 8 as an integral part and a motor drive parameter storage means 10. As shown in FIG. 3, the conventional integrated magnetic bearing control unit 13a includes only the magnetic bearing control circuit 9a, and the motor drive parameter storage unit 10a is provided in the power supply device 2a.
When the operator combines with the model setting means 11 of the power supply device 2a or the power supply device 2a, the model determination means 12 provided in the pump body 8a determines the model dedicated to the model stored in the motor drive parameter storage means provided in the power supply 2a. The parameters are read out, whereby the inverter control circuit 7 of the power supply device is controlled, and the three-phase inverter 5 is driven to control the high-frequency motor of the pump body 8a. On the other hand, the integrated magnetic bearing control unit 13 of the present magnetic bearing type turbo-molecular pump is integrated with the pump body 8 and houses the magnetic bearing control circuit 9 and the motor drive parameter storage means 10, and The drive parameter storage means 10 is an integrated magnetic bearing control unit 1 integrated into the pump body 8.
A motor drive parameter dedicated to the model, such as a high-frequency excitation current for controlling the rotation speed of the high-frequency motor of the pump body 8, a rotation speed, an acceleration time, and a motor current limiter, is stored in the pump body 3. When the pump main body 8 and the power supply device 2 are operated in combination, parameters specific to the model are sent to the inverter control circuit 7 via the magnetic bearing control circuit 9. The inverter control circuit 7 controls the switching phase difference of the switching elements of the three-phase inverter 5 based on the parameters to control the high-frequency output. As described above, since the motor drive parameter storage means 10 is incorporated in the pump body 8 as the integrated magnetic bearing control unit 13, the power supply device 2 can adapt the inverter control circuit to any type of pump body 8 7, the three-phase inverter 5 can be controlled, and the high-frequency motor of the pump body 8 can be driven as specified. The magnetic bearing control circuit 9 includes a drive shaft 28
In a feedback control circuit for magnetically levitating, the output displacement signals from the radial detection sensors 18 and 22 are compared with a reference signal of a target value for position control of the magnetic bearing control circuit 9. The deviation is converted into a PID control signal by the signal processing system of the magnetic bearing control circuit 9, and the exciting current is passed through the power amplifier to the radial magnetic bearings 19 and 21 of the control electromagnet shown in FIG. The drive shaft 28 is attracted to each other by the radial magnetic bearings 19 and 21 of the respective electromagnets disposed opposite to each other with the drive shaft 28 interposed therebetween, and the drive shaft 28 is controlled to an appropriate position, thereby performing magnetic levitation control. ing. The output displacement signal from the sensor 24 for detecting the axial direction is compared with a reference signal of a target value of the floating position control of the magnetic bearing control circuit 9. Then, the deviation is converted into a PID control signal by a signal processing system of the magnetic bearing control circuit 9, and an exciting current is passed through a power amplifier to a thrust magnetic bearing 23 of the control electromagnet shown in FIG. , Thereby performing magnetic levitation control. The power supply device 2 controls an AC / DC converter 3 for converting an AC input of the AC power supply 1 into a DC output, and a model-specific parameter through the magnetic bearing control circuit 9 to control the three-phase inverter 5. And a three-phase inverter 5 that performs DC / AC conversion of a DC input and outputs a three-phase high-frequency AC. The AC / DC converter 3 is a rectifier circuit that converts a single-phase 50/60 Hz AC power supply of the AC power supply 1 into a required DC voltage, and is composed of a transformer, a rectifier, and a capacitor. The output DC voltage is adapted to the input voltage of the three-phase inverter 5. The three-phase inverter 5
Used to obtain AC power from DC power,
Oscillation circuit using transistors, etc. and transformer
Outputs high-frequency AC of the phase. A DC power supply from the AC / DC converter 3 via the rectifier 4 is converted into a three-phase high-frequency AC by an inverter. Then, the primary-side input voltage and frequency are adjusted according to the high-frequency motor of the pump body 8 to rotate the high-frequency motor at high speed. The inverter control circuit 7 receives a model-specific parameter from the motor drive parameter storage means 10 via the magnetic bearing control circuit 9 and controls the switching phase difference of the switching element of the three-phase inverter 5 by the parameter. The high frequency excitation current, rotation speed, acceleration time, motor current limiter, etc. of the high frequency motor suitable for the model of the pump body 8 are controlled, and the high frequency motor is operated. DC /
The DC converter 6 lowers the output voltage of the AC / DC converter 3 and outputs the power supply voltage of the inverter control circuit 7 and the magnetic bearing control circuit 9 and the drive voltage of the control electromagnet. As described above, this magnetic bearing type turbo-molecular pump is
When the power supply device 2 is connected to the pump body 8 for operation, the inverter control circuit 7 stores the motor drive parameter from the magnetic bearing control circuit 9 of the integrated magnetic bearing control unit 13 integrated with the pump body 8. In order to drive the pump body 8 by receiving the model-specific parameters stored in the means 10 and controlling the three-phase inverter 5, there is no need to manually input the model parameters of the pump body 8, and the power supply device is automatically turned on. 2 and the pump body 8 can be used in conformity with the specification. The magnetic bearing type turbo-molecular pump according to the present invention is constructed as described above. The pump main body is provided with storage means for storing a model-specific motor drive parameter. It has an automatic response function that sends the model-specific parameters to the inverter control circuit provided in the power supply unit, controls the high-frequency output of the inverter, and rotates the high-frequency motor of the pump body at high speed as specified. It is automatic and can be used without changing the power supply software. In addition, it is not necessary to manufacture a power supply device for each type of the pump main body, thereby reducing product inventory. In addition, when the user holds the spare power supply in preparation for a failure, the user only needs to hold one kind of power supply even when using a plurality of types of pump bodies.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a view showing one embodiment of a turbo-molecular pump of the present invention. FIG. 2 is a diagram showing a structure of a turbo-molecular pump. FIG. 3 is a diagram showing a control circuit of a conventional turbo-molecular pump. [Description of Signs] 1 AC power supply 2 Power supply device 3 AC / DC converter 4 Rectifier 5 Three-phase inverter 6 DC / DC converter 7 Inverter control circuit 8, 8a Pump body 9, 9a Magnetic bearing Control circuits 10 and 10a Motor drive parameter storage means 11 Model setting means 12 Model determination means 13 and 13a Integrated magnetic bearing control unit 14 Inlet 15 Protection net 16 Rotor blades 17 and 25 Protection Bearings 18, 22, 24 Sensor 19 Radial bearing 20 Power supply terminal 21 Radial magnetic bearing 23 Thrust magnetic bearing 26 Exhaust port 27a Motor stator 27b Motor rotor 28 Drive shaft 29 Spacer 30 Fixed blade 31 ... Main body cylindrical part 32 ... Flange

Continuation of front page    F-term (reference) 3H021 AA01 BA01 BA11 CA04 CA07                       DA06 EA10                 3H022 AA03 BA06 BA07 CA06 CA16                       CA48 CA50 DA09 DA12 DA19                       DA20                 3H031 DA02 EA09 EA11 EA12 EA13                       EA14 EA15 FA01 FA13 FA41                 3H045 AA06 AA09 AA12 AA25 AA26                       AA31 BA01 BA28 BA31 CA09                       CA21 CA28 CA29 DA07 EA36                 3J102 AA01 AA09 BA03 BA17 BA18                       DA02 DA03 DA09 DB05 DB10                       DB22 GA06

Claims (1)

Claims: 1. A pump body provided with a magnetic bearing type motor, a power supply device having an inverter for driving the motor at high frequency, and an integrated magnetic bearing control unit provided in the pump body. In the magnetic bearing type turbo molecular pump for rotating the rotor blades at high speed and exhausting gas molecules, the integrated magnetic bearing control unit is provided with a magnetic bearing control circuit and a storage unit for storing a model-specific motor driving parameter, and stores the storage unit. A magnetic bearing type turbo-molecular pump wherein a motor driving parameter is sent from the means to an inverter control circuit in a power supply device via the magnetic bearing control circuit, and the motor is rotated at a high speed by controlling the inverter.