JP2009092044A - Control device and control method of vacuum pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control device and a control method of a vacuum pump capable of inhibiting occurrence of an overload trip and an overvoltage trip by effectively utilizing regenerative energy generated during normal operation in the two stage vacuum pump. <P>SOLUTION: This device is provided with a first motor drive means 5 driving a first motor 52, a second motor drive means 6 driving a second motor 54, a regenerative electric power extraction means 4 extracting regenerative electric power generated by the first motor drive means 5 or the second motor drive means, and a control means 20 controlling operation of the first motor drive means 5 and the second motor drive means 6. The first motor drive means 5 and the second motor drive means 6 are connected in parallel with the regenerative electric power extraction means 4. The control means 20 executes control to supply regenerative electric power extracted from one of the first motor drive means 5 and the second motor drive means 6 by the regenerative electric power extraction means 4 to another motor drive means. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a control device and a control method for a vacuum pump, and more particularly to a control device and a control method for a vacuum pump that can effectively use regenerative energy generated during steady operation in a two-stage vacuum pump.

A vacuum pump such as a turbo molecular pump evacuates when a screw rotor rotates at a high speed, and puts a connected chamber or the like in a vacuum state.
In such a vacuum pump, for example, when it is attempted to stop the rotation of the rotor in a high speed state, regenerative energy is generated along with deceleration. This regenerative energy is generated when the actual speed of the motor becomes faster than the inverter output (frequency) for controlling the motor when the rotation of the rotor is stopped suddenly.
That is, regeneration refers to a state in which the motor acts as a generator and attempts to return the energy generated thereby to the inverter.

Further, this regenerative energy is conventionally converted into, for example, electric energy in a vacuum pump and used as an auxiliary power source for a magnetic bearing of a magnetic levitation turbomolecular pump, an exhaust chamber heater, and a lubricating oil pump (Patent Document 1). To Patent Document 4).
Japanese Patent Laid-Open No. 1-301999 JP-A-2-42196 JP 2002-180990 A JP 2002-285993 A

By the way, in the configuration of the two-stage vacuum pump shown in FIG. 6, when a sudden inflow of process gas occurs in the booster pump BP, regenerative power is generated in the main pump MP.
4 and the graph of FIG. 5, when a sudden load fluctuation occurs due to an increase in the flow of process gas during the steady operation (step S1) (step S2), the booster in the previous stage In the pump BP, the load increases, and the rotational speed of the motor 52 that rotates the screw rotor 51 decreases (step S3).

  The booster pump BP is in an accelerated state in order to return the reduced number of rotations of the motor 52 to the rated number of rotations. As a result, when a power consumption larger than a predetermined value is generated (step S4), an overload trip state is entered (step S5). If the power consumption is within a predetermined allowable value, the steady operation is performed (step S6).

  On the other hand, in the main pump MP, when an excessive load fluctuation occurs due to an increase in gas flow into the booster pump BP (step S2), gas flow from the booster pump BP increases. For this reason, the pressure in the intermediate pipe 65 connecting the booster pump BP and the main pump MP and the pressure difference in the main pump MP are reduced, and the load on the main pump MP is reduced. When the load decreases, since the motor control is performed in accordance with the load up to that point, the rotational speed of the motor 54 that rotates the screw rotor 53 instantaneously increases (step S7).

As a result, the inverter circuit controls the motor 54 of the main pump MP to decelerate, where regenerative power is generated, and if the value is within the allowable range, the operation returns to the normal operation (step S6). An overvoltage trip occurs (step S9).
Thus, in the case of a two-stage vacuum pump, regenerative energy is generated in the main pump (MP) when a large amount of process gas is sucked in by the booster pump (BP) not only during stop control but also during operation. It was.
However, the regenerative energy was converted into heat energy and consumed without being effectively used.

  The present invention has been made under the circumstances as described above, and in a two-stage vacuum pump, regenerative energy generated during steady operation is effectively used to suppress the occurrence of overload trips and overvoltage trips. An object of the present invention is to provide a control device and a control method for a vacuum pump.

  In order to solve the above-described problems, a vacuum pump control device according to the present invention is a two-stage vacuum pump in which exhaust from a first pump is sucked and exhausted by a second pump. A control device for a vacuum pump for controlling a first motor and a second motor to be rotated, the first motor driving means for driving the first motor, and the second for driving the second motor. Motor driving means, regenerative power extracting means for extracting regenerative power generated in the first motor driving means or the second motor driving means, the first motor driving means, and the second motor driving means. Control means for performing operation control, wherein the first motor driving means and the second motor driving means are connected in parallel to the regenerative power extraction means, and the control means includes the regenerative power extraction means. It means having features that performs control so as to supply to the other motor driving means regenerative power extracted from one of said first motor drive means the second motor drive means.

For example, when an abrupt load is generated due to an inflow of process gas to the first pump, an acceleration state is brought about in order to return the reduced speed of the first motor to the rated speed, thereby requiring a predetermined power. It becomes. On the other hand, in the second pump, since the load is instantaneously reduced, the rotation speed of the second motor is increased, thereby generating regenerative power.
However, according to the configuration of the present invention, the first motor driving means and the second motor driving means are connected in parallel to the regenerative power extracting means, so that the first pump When a load is generated, the regenerative power generated in the second motor driving unit is consumed as necessary power in the first motor driving unit.
Therefore, the voltage of the first motor driving means and the second motor driving means is maintained substantially constant regardless of the occurrence of a sudden load fluctuation, and a phenomenon such as overload trip or overvoltage trip as in the prior art is avoided. Can do.

  In order to solve the above-described problems, a method for controlling a vacuum pump according to the present invention is a two-stage vacuum pump that sucks and exhausts exhaust from a first pump from a second pump. A vacuum pump control method for controlling a first motor and a second motor that respectively rotate the motor, wherein the first motor driving means for driving the first motor and the second motor are driven. It is characterized in that the regenerative electric power generated in one of the second motor driving means is extracted and the extracted regenerative electric power is supplied to the other motor driving means.

For example, when an abrupt load is generated due to an inflow of process gas to the first pump, an acceleration state is brought about in order to return the reduced speed of the first motor to the rated speed, thereby requiring a predetermined power. It becomes. On the other hand, in the second pump, since the load is instantaneously reduced, the rotation speed of the second motor is increased, thereby generating regenerative power.
However, according to the control method of the present invention, for example, when a sudden load is generated in the first pump, the regenerative power generated in the second motor driving unit is required in the first motor driving unit. Consumed as electric power.
Therefore, the voltage of the first motor driving means and the second motor driving means is maintained substantially constant regardless of the occurrence of a sudden load fluctuation, and a phenomenon such as overload trip or overvoltage trip as in the prior art is avoided. Can do.

  According to the present invention, in a two-stage vacuum pump, there is provided a control device and a control method for a vacuum pump capable of effectively utilizing regenerative energy generated during steady operation and suppressing occurrence of an overload trip and an overvoltage trip. Can be provided.

Embodiments of a vacuum pump control apparatus according to the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view schematically showing an embodiment of a vacuum pump control apparatus according to the present invention.
The vacuum pump control device 100 shown in FIG. 1 can be applied to a two-stage vacuum pump 200 as shown in FIG.

As shown in the figure, this vacuum pump control device 100 is configured such that a motor 52 (first motor) and a motor 54 (second motor) are rotated at a predetermined rotation from an AC power source 101 having a commercial (three-phase AC) frequency band. The inverter circuit 1 that performs power conversion so as to obtain a number and the control unit 20 (control means) that controls the inverter circuit 110 are configured.
As shown in FIG. 6, the motor 52 is a motor that rotates the screw rotor 51 of the booster pump BP (first pump), and the motor 54 is the screw rotor 53 of the main pump MP (second pump). It is a motor which rotates.

The inverter circuit 1 includes a rectifier 2 that converts the electric power of the AC power supply 101 into a direct current, and a direct current smoothing capacitor 3 that smoothes the current converted into a direct current by the rectifier 2 into a predetermined value. An inverter unit 5 (first motor driving means) that is connected to the motor 52 and supplies predetermined power to the motor 52, and an inverter unit 6 that is connected to the motor 54 and supplies predetermined power to the motor 54. (Second motor driving means). Further, based on the output of the DC smoothing capacitor 3 and the voltage values of the inverter units 5 and 6, an overvoltage detection circuit 4 (regenerative power extraction) that detects whether or not the voltage of the inverter units 5 and 6 exceeds a predetermined value. Means).
The inverter unit 5 and the inverter unit 6 are connected in parallel to the overvoltage detection circuit 4.

  Subsequently, in the two-stage vacuum pump 200 (see FIG. 6) controlled by the vacuum pump control device 1 configured as described above, the operation of the control device 1 when an excessive load occurs is shown in the flow chart of FIG. This will be described with reference to the graph of FIG.

During a steady operation (step ST1), when a sudden load fluctuation occurs due to an increase in the flow of process gas or the like (step ST2), the load increases in the booster pump BP in the preceding stage, and the rotation speed of the motor 52 decreases ( Step ST3).
The booster pump BP is in an accelerated state in order to return the reduced rotational speed of the motor 52 to the rated rotational speed, and a predetermined power consumption is generated (step ST5).

On the other hand, in the main pump MP, when an excessive load fluctuation occurs due to an increase in gas flow into the booster pump BP (step ST2), gas flow from the booster pump BP increases.
For this reason, the pressure in the intermediate pipe 65 connecting the booster pump BP and the main pump MP and the pressure difference in the main pump MP are reduced, and the load on the main pump MP is reduced. When the load decreases, the motor control is performed by the control unit 20 corresponding to the load so far, and therefore the rotational speed of the motor 54 increases instantaneously (step ST4).
Thus, the inverter unit 6 controls the motor 54 of the main pump MP to be decelerated under the control of the control unit 20, but regenerative power is generated due to the deceleration.

Here, the inverter unit 6 is connected in parallel to the inverter unit 5 as shown in FIG.
For this reason, the regenerative power of the inverter unit 6 detected by the overvoltage detection circuit 4 is used for power consumption in the inverter unit 5 required in step ST5 under the control of the control unit 20 (step ST5).
Accordingly, the steady operation is continued without excessively increasing the voltage of the inverter unit 6 as shown in the graph of FIG. 3 (step ST6).

As described above, according to the embodiment of the present invention, when an abrupt load is generated in the booster pump BP, etc., regenerative power is generated in the inverter unit 6, while the inverter unit 5 responds to the regenerative power. More predetermined power is required.
However, in the control device 1 according to the present invention, the inverter unit 5 that drives the motor 52 and the inverter unit 6 that drives the motor 54 are connected in parallel to the overvoltage detection circuit 4. For this reason, the regenerative power generated in the inverter unit 6 is consumed as necessary power in the inverter unit 5.
Therefore, the voltages of the inverter units 5 and 6 are maintained substantially constant regardless of the occurrence of a sudden load fluctuation, and a phenomenon such as an overload trip or an overvoltage trip can be avoided as in the prior art.

The present invention is particularly effective when a screw-type vacuum pump that compresses and exhausts a volume is used as a booster pump.
That is, when a screw type vacuum pump that compresses and exhausts volume is used as a booster pump, the screw type vacuum pump as the main pump is also small, so the exhaust of the main pump is not in time due to an increase in the flow of process gas, etc. This is because the compression of the intermediate pipe is particularly likely to increase rapidly.

  The present invention can be suitably used for a vacuum pump provided with a screw rotor used in a process gas flow process such as a semiconductor manufacturing process.

FIG. 1 is a cross-sectional view schematically showing an embodiment of a control device for a vacuum pump according to the present invention. FIG. 2 is a flowchart showing the operation of the control device when an excessive load is generated in the two-stage vacuum pump controlled by the control device of FIG. FIG. 3 is a graph showing the state of the booster pump and the main pump corresponding to the flow of FIG. FIG. 4 is a flowchart showing the operation of the control device when an excessive load is generated in the two-stage vacuum pump controlled by the conventional control device. FIG. 5 is a graph showing the state of the booster pump and the main pump corresponding to the flow of FIG. FIG. 6 is a cross-sectional view showing a schematic configuration of a two-stage vacuum pump.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Inverter circuit 2 Rectifier 3 DC smoothing capacitor 4 Overvoltage detection circuit (regenerative current extraction means)
5 Inverter unit (first motor drive means)
6 Inverter unit (second motor drive means)
20 Control unit (control means)
51 Screw rotor 52 Motor (first motor)
53 Screw rotor 54 Motor (second motor)
65 Intermediate piping 100 Vacuum pump control device 101 AC power supply 200 Two-stage vacuum pump BP Booster pump (first pump)
MP main pump (second pump)

Claims (2)

In a two-stage vacuum pump that draws and exhausts exhaust from a first pump by a second pump, a vacuum pump control device that controls a first motor and a second motor that respectively rotate a screw rotor of each pump Because
Occurs in the first motor driving means for driving the first motor, the second motor driving means for driving the second motor, and the first motor driving means or the second motor driving means. Regenerative power extraction means for extracting regenerative power, and control means for controlling operation of the first motor drive means and the second motor drive means,
The first motor driving means and the second motor driving means are connected in parallel to the regenerative power extracting means,
The control means performs control so that the regenerative power extraction means supplies the regenerative power extracted from one of the first motor drive means and the second motor drive means to the other motor drive means. A vacuum pump control device. In a two-stage vacuum pump that exhausts the exhaust of the first pump from the second pump, and controls the first motor and the second motor that rotate the screw rotor of each pump, respectively. Because
Extracting regenerative electric power generated in one of the first motor driving means for driving the first motor and the second motor driving means for driving the second motor;
A method for controlling a vacuum pump, wherein the extracted regenerative power is supplied to the other motor driving means.

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