JP2021035158A - Vacuum evacuation device and operation method thereof - Google Patents

Abstract

To provide a vacuum evacuation device which can make circuit components for absorbing regenerative voltage such as brake resistance unnecessary and an operation method thereof.SOLUTION: A vacuum evacuation device concerning one aspect of the present invention is equipped with: a first vacuum pump; a second vacuum pump; and a power supply part. The first vacuum pump comprises: a first pump body having a first motor; and a first drive circuit which drives the first motor. The second vacuum pump comprises: a second pump body having a second motor and connected with a rear stage of the first pump body; and a second drive circuit which drives the second motor. The power supply part comprises a conduction line which can electrically connect between the first drive circuit and the second drive circuit.SELECTED DRAWING: Figure 2

Description

The present invention relates to a pump device including a first vacuum pump and a second vacuum pump connected to a subsequent stage of the first vacuum pump, and an operation method thereof.

Dry pumps such as mechanical booster pumps and screw pumps are volume transfer type vacuum pumps that transfer gas from the intake port to the exhaust port by synchronously rotating two pump rotors arranged in the pump chamber inside the casing in opposite directions. Is. Since there is no contact between both pump rotors and between each pump rotor and the casing, this type of vacuum pump has very little mechanical loss, and is suitable for vacuum pumps with large friction work such as oil rotary vacuum pumps. In comparison, it has the advantage that the energy required for driving can be reduced. Further, a vacuum exhaust device having a structure in which a plurality of dry pumps of this type are connected in multiple stages is widely known (see, for example, Patent Document 1).

On the other hand, this type of dry pump includes a motor driven by a drive circuit including a rectifier circuit and an inverter circuit. The motor is typically a three-phase brushless synchronous motor that rotates the pump rotor with the supply of drive current generated by the inverter circuit. A drive circuit of this type is known to have a braking resistor that absorbs a regenerative voltage generated by the motor when the torque of the motor is regenerated (see, for example, Patent Document 2).

International Publication No. 2012/124277 Japanese Unexamined Patent Publication No. 3-27788

For example, in a multi-stage vacuum exhaust device including a first vacuum pump connected to a vacuum chamber and a second vacuum pump connected to a subsequent stage, the pressure inside the vacuum chamber is increased due to the introduction of process gas or the like. When the temperature rises sharply, the first vacuum pump may perform control to temporarily reduce the number of revolutions in order to reduce the load on the motor. At this time, a pressure is generated between the first vacuum pump and the second vacuum pump, and the pump rotor of the first vacuum pump is rotated by the pressure on the intake side of the second vacuum pump to rotate the pump rotor of the first vacuum pump. Excessive regenerative voltage may occur in the pump motor.

Further, in the vacuum exhaust device having the above structure, control is performed to reduce the rotation speed of the second vacuum pump for the purpose of reducing the power consumption of the second vacuum pump when the vacuum chamber reaches a predetermined pressure or less. May be executed. In this case as well, a pressure is generated between the first vacuum pump and the second vacuum pump, and the pump rotor of the second vacuum pump is rotated by the pressure on the exhaust side of the first vacuum pump to rotate the pump rotor of the second vacuum pump. Excessive regenerative voltage may occur in the pump motor.

When these regenerative voltages become so large that they exceed the withstand voltage of the elements of each part such as the inverter circuit constituting the drive circuit as a result, the drive circuit may be deteriorated or damaged. For this reason, it is necessary to install circuit parts that absorb regenerative voltage such as braking resistance in the drive circuit, and an increase in the number of parts becomes a problem.

In view of the above circumstances, an object of the present invention is to provide a vacuum exhaust device and an operation method thereof that can eliminate the need for circuit parts for absorbing regenerative voltage such as braking resistance.

In order to achieve the above object, the vacuum exhaust device according to one embodiment of the present invention includes a first vacuum pump, a second vacuum pump, and a power supply unit.
The first vacuum pump has a first pump body having a first motor and a first drive circuit for driving the first motor.
The second vacuum pump has a second pump body having a second motor and connected to the subsequent stage of the first pump body, and a second drive circuit for driving the second motor. ..
The power supply unit has an energizing line that can be electrically connected between the first drive circuit and the second drive circuit.

In the vacuum exhaust device, since the first drive circuit and the second drive circuit are configured to be connectable to each other via an energization line, the regenerative voltage generated by the motor of the first vacuum pump is the second. It can be supplied to the drive circuit, and the regenerative voltage generated by the motor of the second vacuum pump can be supplied to the first drive circuit. As a result, the drive circuit can be protected from the regenerative voltage without requiring circuit components for absorbing the regenerative voltage in the first drive circuit and the second drive circuit, respectively.

The first drive circuit and the second drive circuit each include a rectifier circuit unit that rectifies an alternating current, a smoothing circuit unit that includes a smoothing capacitor, and an inverter circuit unit that generates a motor drive current. May be good.

The power supply unit may further include a switch circuit capable of switching between electrical connection between the first drive circuit and the second drive circuit and disconnection thereof.

The vacuum exhaust device may further include a control unit that controls switching of the switch circuit.

When the regenerative voltage in the first drive circuit and / or the second drive circuit is equal to or higher than a predetermined value, the control unit electrically connects the first drive circuit and the second drive circuit. It may be configured to control the switch circuit so as to be connected to.

The control unit is such that when the power supply of the first drive circuit and the second drive circuit is stopped, the first drive circuit and the second drive circuit are electrically connected to each other. May be configured to control the switch circuit.

The first vacuum pump may be a single-stage mechanical booster pump, and the second vacuum pump may be a multi-stage dry pump.

A method of operating a vacuum exhaust device according to an embodiment of the present invention includes driving a first vacuum pump and a second vacuum pump connected to a subsequent stage of the first vacuum pump.
When the motor of the first vacuum pump generates a regenerative voltage, the energization line connected between the drive circuit of the first vacuum pump and the drive circuit of the second vacuum pump is used. The regenerative voltage is supplied to the drive circuit of the second vacuum pump.
When the motor of the second vacuum pump generates a regenerative voltage, the regenerative voltage is supplied to the drive circuit of the first vacuum pump via the energizing line.

According to the present invention, it is possible to eliminate the need for circuit components for absorbing regenerative voltage such as braking resistance.

It is a schematic block diagram which shows the vacuum exhaust device which concerns on 1st Embodiment of this invention. It is a block diagram which shows the internal structure of the controller in the said vacuum exhaust device. It is a circuit diagram which shows one configuration example of the 1st drive circuit and the 2nd drive circuit in the said vacuum exhaust device. It is a flowchart explaining the operation method of the said vacuum exhaust device. It is a schematic diagram explaining the operation of the said vacuum exhaust device. It is a figure explaining the operation of the said vacuum exhaust device, and is explanatory drawing which shows an example of the time change of the internal pressure of a vacuum chamber, and the time change of the power of the 1st and 2nd vacuum pumps. It is a schematic block diagram which shows the vacuum exhaust device which concerns on 2nd Embodiment of this invention. It is a schematic diagram explaining the operation of the said vacuum exhaust device. It is explanatory drawing which shows an example of the time change of the power of the 1st and 2nd vacuum pumps. It is a flowchart explaining the operation method of the said vacuum exhaust device. It is a flowchart explaining the operation method of the vacuum exhaust device which concerns on 3rd Embodiment of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

<First Embodiment>
FIG. 1 is a schematic configuration diagram showing a vacuum exhaust device 100 according to an embodiment of the present invention. The vacuum exhaust device 100 includes a first vacuum pump 110 as a main pump, a second vacuum pump 120 as an auxiliary pump, and a controller 130.

The first vacuum pump 110 is a volume transfer type dry pump having a higher exhaust speed than the second vacuum pump 120, and in the present embodiment, a mechanical booster pump is adopted. The first vacuum pump 110 includes a pump main body 111 (first pump main body) incorporating a single-stage pump rotor R1 and a motor 112 (first motor) for rotating the pump rotor R1. The pump main body 111 has an intake port E11 connected to the vacuum chamber 1 via the pipe L1 and an exhaust port E12 connected to the second vacuum pump 120 via the pipe L2.

The second vacuum pump 120 is a volume transfer type dry pump connected to the subsequent stage of the first vacuum pump 110, and is a screw pump in this embodiment. The second vacuum pump 120 has a pump main body 121 (second pump main body) incorporating a multi-stage pump rotor (screw rotor) R2, and a motor 122 (second motor) for rotating the pump rotor R2. The pump main body 121 has an intake port E21 connected to an exhaust port E12 of the first vacuum pump 110 via a pipe L2, and an exhaust port E22 communicating with the atmosphere. The second vacuum pump 120 is typically started at the start of operation of the first vacuum pump 110 and is always driven during the operation of the first vacuum pump 110.

The motors 112 and 122 are brushless DC motors, and in the present embodiment, the motors 112 and 122 are composed of a permanent magnet synchronous type can motor in which a permanent magnet is attached to the peripheral surface of the rotor core or the inside thereof. By rotating the pump rotor R1, the motor 112 transfers the gas in the vacuum chamber 1 sucked through the intake port E11 toward the exhaust port E12. By rotating the pump rotor R2, the motor 122 transfers the back pressure of the first vacuum pump 110 sucked through the intake port E21 toward the exhaust port E22.

The controller 130 is configured as a control unit that controls the operations of the first vacuum pump 110 and the second vacuum pump 120. The controller 130 has a first drive circuit 51 that drives the motor 112 and a second drive circuit 52 that drives the motor 122.

FIG. 2 is a block diagram showing an internal configuration of the controller 130. The controller 130 includes a first drive circuit 51 that drives the motor 112 of the first vacuum pump 110, a second drive circuit 52 that drives the motor 122 of the second vacuum pump 120, and a first drive circuit 51. It also has a control unit 53 that controls the second drive circuit 52.

FIG. 3 is a circuit diagram showing a configuration example of the first drive circuit 51 and the second drive circuit 52. The first drive circuit 51 and the second drive circuit 52 each have a similar configuration. That is, the first drive circuit 51 and the second drive circuit 52 each include a rectifier circuit unit 5a, a smoothing circuit unit 5b, and an inverter circuit unit 5c.

The rectifier circuit unit 5a is connected to the three-phase AC power supply 60, which is a commercial power source, and rectifies the alternating current supplied from the three-phase AC power supply 60. The smoothing circuit unit 5b is for smoothing the output of the rectifying circuit unit 5a, and is composed of a choke coil input type smoothing circuit including a choke coil L and smoothing capacitors C (C1 and C2). The inverter circuit unit 5c has a plurality of semiconductor switching elements Tr that generate a drive current (motor drive current) that rotates the motors 112 and 122 at a predetermined rotation speed (for example, 5000 rpm). These semiconductor switching elements Tr are composed of transistors such as MOSFETs and IGBTs, and the opening / closing timing is individually controlled by the control unit 53 to control the opening / closing timings of the motors 112 and 122 (U-phase, V-phase, and W-phase). Generates the drive current (rated current) supplied to the winding.

The first drive circuit 51 and the second drive circuit 52 are configured to be electrically connectable via the power supply unit 54. The power supply unit 54 includes an energization line 541 connected between the first drive circuit 51 and the second drive circuit 52, and the first drive circuit 51 and the second drive circuit via the energization line 541. It has a switch circuit 542 capable of switching between electrical connection with 52 and disconnection thereof.

The energizing line 541 is connected between the high-voltage side wiring of the first drive circuit 51 and the high-voltage side wiring of the second drive circuit 52. In the present embodiment, the energization line 541 connects the DC voltage units (for example, between the rectifier circuit unit 5b and the inverter circuit unit 5c) of the first and second drive circuits 51 and 52 to each other. The low-voltage side wirings of the first and second drive circuits 51 and 52 are connected to the ground potential.

The switch circuit 542 is connected to the energization line 541. The switch circuit 542 is composed of switching elements such as a mechanical switch and a semiconductor switch, and its opening and closing is controlled by a control unit 53. The switch circuit 542 is typically a normal-off (A-contact) switch.

The control unit 53 controls the first drive circuit 51 and the second drive circuit 52. Further, the control unit 53 controls the switching of the switch circuit 542 of the power supply unit 54. The control unit 53 typically includes a CPU and a computer including a memory for storing various programs and control parameters for controlling the operation of the vacuum exhaust device 100.

The control unit 53 has a monitoring unit that monitors the circuit voltage of the first drive circuit 51. As will be described later, the control unit 53 is configured to execute control to turn on (short-circuit) the switch circuit 542 when the circuit voltage of the first drive circuit 51 exceeds a predetermined value.

As will be described later, the monitoring unit may be configured to be able to monitor the circuit voltage of the second drive circuit 52 in addition to or instead of the monitoring voltage of the first drive circuit 51. In this case, the control unit 53 is configured to execute control to turn on (short-circuit) the switch circuit 542 when the circuit voltage of the second drive circuit 52 exceeds a predetermined value.

For example, when a regenerative voltage is generated in the motor 112 of the first vacuum pump 110 and the voltage exceeds the rated voltage of the inverter circuit unit 5c in the first drive circuit 51, the control unit 53 turns on the switch circuit 542. Make it work. As a result, the first drive circuit 51 is protected from overvoltage, and the first drive circuit 51 and the second drive circuit 52 are electrically balanced.

Hereinafter, the details of the control unit 53 will be described together with the operation of the vacuum exhaust device 100.

At the start of operation of the vacuum exhaust device 100, the switch circuit 542 is in the off state. When the operation of the vacuum exhaust device 100 is started, the control unit 53 drives the first vacuum pump 110 by generating a drive current in the first drive circuit 51 and supplying the drive current to the motor 112. The pump rotor R1 of the first vacuum pump 110 is rotated by a motor 112 at a predetermined rated rotation speed (for example, 5000 rpm) to transfer gas from the intake port E11 to the exhaust port E12. As a result, the inside of the vacuum chamber 1 is exhausted to a predetermined depressurized atmosphere.

The control unit 53 further generates a drive current in the second drive circuit 52 and supplies the drive current to the motor 122 to drive the second vacuum pump 120. The pump rotor R2 of the second vacuum pump 120 transfers gas from the intake port E21 to the exhaust port E22 by rotating at a predetermined rated rotation speed (for example, 5000 rpm) by the motor 122. As a result, the back pressure of the first vacuum pump 110 is exhausted, and the power consumption of the first vacuum pump 110 (motor 112) can be reduced.

FIG. 4 is a flowchart illustrating an operation method of the vacuum exhaust device 100 executed by the control unit 53. As shown in FIG. 4, the control unit 53 monitors the magnitude of the regenerative voltage that can be generated in the motor 112 of the first vacuum pump 110 during the operation of the vacuum exhaust device 100, and when this is equal to or more than a predetermined value, The switch circuit 542 is configured to perform an operation of switching from an off state to an on state.

5 (a) to 5 (c) are schematic views of the vacuum exhaust device 100 for explaining the operation of the present embodiment, and FIGS. 6 (a) and 6 (b) show the time change of the internal pressure of the vacuum chamber 1 and the first. It is explanatory drawing which shows an example of the time change of the power of the 1st and 2nd vacuum pumps 110, 120 (motors 112, 122).

When a large amount of process gas is introduced into the vacuum chamber 1 while the vacuum chamber 1 is maintained in a predetermined depressurized atmosphere, the internal pressure of the vacuum chamber 1 rises sharply (FIGS. 5 (a) and 6 (a). ) Time t1). At this time, since the exhaust speed of the first vacuum pump 110 is higher than the exhaust speed of the second vacuum pump 120, the exhaust by the second vacuum pump 120 cannot catch up and is indicated by a black arrow in FIG. 5 (b). As described above, the gas discharged toward the second vacuum pump 120 may flow back toward the first vacuum pump 110 (the region concerned is boosted). This phenomenon becomes more remarkable as the amount of process gas introduced into the vacuum chamber 1 increases.

In the first vacuum pump 110, the load torque of the motor 112 becomes excessive, and the control unit 53 limits the drive current by the first drive circuit 51, for example, in order to protect the motor 112 from the overload. As a result, the motor 112 changes from speed control having a target speed to a state similar to torque control, and although the rotation speed of the pump rotor R1 decreases, the state of exerting almost the maximum torque continues. If the exhaust gas from the second vacuum pump 120 cannot catch up, the pressure in the region is increased, and finally the pressure in the exhaust port E12 side region becomes higher than that in the intake port E11 side region. This is because gas compression has a time delay element, which is caused by the dynamic characteristics of the motor 112. As a result, a phenomenon occurs in which the torque of the motor 112 reverses from power running to regeneration.

As described above, a pressure is generated between the first vacuum pump 110 and the second vacuum pump 120, and as shown in FIGS. 5 (b) and 5 (c), the intake side of the second vacuum pump 120 The pressure accelerates the rotation of the pump rotor R1 of the first vacuum pump 110 from the decelerated state (due to the pressure difference between the pressure on the intake side of the first vacuum pump 110 and the pressure on the intake side of the second vacuum pump 120). Since the phenomenon (which receives the resulting force) and the drive current limit interfere with each other, a gas pulsation phenomenon or the like may occur. At this time, the regenerative voltage generated in the motor 112 may become excessive enough to exceed the withstand voltage of the power element constituting the inverter circuit unit 5c.

Therefore, in the present embodiment, the control unit 53 monitors the regenerative voltage in the first drive circuit 51 generated by the motor 112, and the magnitude thereof exceeds a predetermined value (for example, an arbitrary value exceeding the rated voltage of the inverter circuit unit 5c). ) In the above case, the control for switching the switch circuit 542 from the off state to the on state is executed (steps 101 and 102 in FIG. 4). When the switch circuit 542 is switched to the ON state, the circuit voltage of the first drive circuit 51 is supplied to the second drive circuit 52 via the energization line 541, and the first drive circuit 51 and the second drive circuit 52 Are electrically balanced with each other. Thereby, the first drive circuit 51 can be protected from the excessive regenerative voltage of the motor 112.

Further, according to the present embodiment, a circuit component for absorbing the regenerative voltage such as a braking resistor for protecting the circuit from an excessive regenerative voltage becomes unnecessary. As a result, the circuit configuration of the first drive circuit 51 can be simplified and the component cost can be reduced.

Further, when an excessive regenerative voltage is generated in the motor 112, an excess voltage component in the first drive circuit 51 is supplied to the second drive circuit 52 via the energizing line 541, so that the voltage is applied to the motor 112. The action of returning the torque of the motor 112 from regeneration to power running is accelerated because the voltage of the motor 112 rises. As a result, the stop period of the pump operation in the first vacuum pump 110 is shortened, and the pulsation phenomenon of the gas that may occur in the first vacuum pump 110 can be reduced. Such an effect is more remarkable as the exhaust volume ratio of the first vacuum pump 110 to the second vacuum pump 120 is smaller.

The control unit 53 calculates the elapsed time of the switch circuit 542 in the on state, and after the elapsed time elapses, returns the switch circuit 542 to the off state (steps 103 and 104 in FIG. 4). As a result, the electrical continuity between the first drive circuit 51 and the second drive circuit 52 is cut off, and the individual operation control of the first vacuum pump 110 and the second vacuum pump 120 is restarted. The predetermined time is not particularly limited, and is typically set to a time sufficient to eliminate the excessive regenerative voltage generated by the motor 112. Further, if the regenerative voltage is monitored by the control unit 53 and the switch circuit 542 is turned off when the voltage is equal to or lower than the withstand voltage of the semiconductor switching element Tr of the inverter circuit unit 5c, the torque of the motor 112 can be increased more quickly. It is preferable in that it can be restored to power running. After that, the above-mentioned process is repeatedly executed. It is desirable that the monitoring value of the regenerative voltage is a value obtained by multiplying the withstand voltage of the semiconductor switching element Tr by an arbitrary safety factor.

Note that FIG. 6B shows an example in which the power of the first vacuum pump 120 gradually increases due to the return of the torque of the motor 112 from the regeneration to the power running, and the peak of the power appears at time t3. .. On the other hand, with respect to the second vacuum pump 120, an example is shown in which the power increases in response to an increase in the internal pressure of the first vacuum pump 120 due to the suction of the process gas, and the power reaches the maximum value at time t2. The time change of these powers is only an example, and may show different modes depending on the volume ratio of the first and second vacuum pumps 110 and 120, the pump characteristics, and the like.

In the present embodiment, since the voltage rise of the first drive circuit 51 is suppressed by electrically equilibrating the first drive circuit 51 and the second drive circuit 52, acceleration / deceleration of the motor 112 is performed. Controllability is improved, and overshoot of the rotation speed during acceleration control can be prevented.

<Second embodiment>
Subsequently, a second embodiment of the present invention will be described. FIG. 7 is a schematic configuration diagram showing the vacuum exhaust device 200 of the present embodiment. Hereinafter, configurations different from those of the first embodiment will be mainly described, and the same configurations as those of the first embodiment are designated by the same reference numerals, and the description thereof will be omitted or simplified.

As shown in FIG. 2, the vacuum exhaust device 200 of the present embodiment includes a first vacuum pump 110, a second vacuum pump 120 located in a subsequent stage, and a controller 130. However, it differs from the first embodiment in that the exhaust port E22 of the second vacuum pump 120 communicates with the atmosphere via the check valve 140. The check valve 140 is a valve member whose forward direction is the flow of gas from the exhaust port E22 toward the atmosphere, and typically, when the pressure of the gas discharged from the exhaust port E22 is atmospheric pressure or higher. It is configured to be able to open the valve.

In the vacuum exhaust device 200 of the present embodiment, the control unit 53 is configured to be able to execute the power saving operation control of the second vacuum pump 120. That is, in the vacuum exhaust device 200 of the present embodiment, since the check valve 140 is connected to the intake port E22 of the second vacuum pump 120, it is possible to prevent the backflow of the atmosphere to the exhaust port E22, and the pump rotor R2 The load torque can be reduced as compared with the case where the check valve 140 is not provided. Therefore, for example, as shown in FIG. 8, when the motor 122 of the second vacuum pump 120 has a predetermined torque or less, the rotation speed of the motor 122 is set to a predetermined control rotation speed (for example, 5000 rpm) lower than the rated rotation speed (for example, 5000 rpm). For example, by reducing the pressure to 3000 rpm), it is possible to reduce the power consumption of the second vacuum pump 120.

On the other hand, when the second vacuum pump 120 switches from the rated rotation speed to the control rotation speed and a large amount of process gas is introduced into the first vacuum pump 110, the first vacuum pump 110 and the second vacuum pump 120 A pressure is generated between the two, and the pump rotor R2 of the second vacuum pump 120 is rotated by the pressure on the exhaust side of the first vacuum pump 110, and an excessive regenerative voltage is generated by the motor 122 of the second vacuum pump 120. May occur. This phenomenon becomes more remarkable as the exhaust volume of the second vacuum pump 120 is smaller than the exhaust volume of the first vacuum pump 110.

8 (a) and 8 (b) are schematic views of a vacuum exhaust device 200 for explaining the operation of the present embodiment, and FIG. 9 shows first and second vacuum pumps 110 and 120 (motors 112 and 122). It is explanatory drawing which shows an example of the time change of the power of. FIG. 10 is a flowchart illustrating an operation method of the vacuum exhaust device 200 executed by the control unit 53.

For example, when the second vacuum pump 120 is switched from the rated rotation speed (FIG. 8 (a)) to the control rotation speed (FIG. 8 (b)) at time t1 in FIG. 9, the motor 122 of the second vacuum pump 120 Is a state of controlled operation in which the rotation speed is reduced from the rated rotation speed to the control rotation speed. Here, at time t2, a large amount of process gas is introduced from the first vacuum pump 110, the pressure of the first vacuum pump 110 increases, and a pressure is generated between the first vacuum pump 110 and the second vacuum pump 120. The torque of the motor 122 changes from power running to regeneration. On the other hand, when the exhaust volume ratio of the first vacuum pump 110 and the second vacuum pump 120 is relatively large, the exhaust pressure of the first vacuum pump 110 is the second, as shown by the black arrow in FIG. 8 (b). The rotation speed of the pump rotor R2 of the vacuum pump 120 is accelerated, and the regenerative voltage generated in the motor 122 may become excessive enough to exceed the withstand voltage of the power element constituting the inverter circuit unit 5c.

Therefore, in the present embodiment, as shown in FIG. 10, the control unit 53 monitors the regenerative voltage in the second drive circuit 52 generated by the motor 122, and the magnitude thereof is a predetermined value (for example, the second drive circuit). When it is equal to or higher than the rated voltage of the inverter circuit unit 5c in 52), control for switching the switch circuit 542 of the power supply unit 54 from the off state to the on state is executed (steps 201 and 202). When the switch circuit 542 is switched to the ON state, the circuit voltage of the second drive circuit 52 is supplied to the first drive circuit 51 via the energization line 541, and the first drive circuit 51 and the second drive circuit 52 Are electrically balanced with each other. Thereby, the second drive circuit 52 can be protected from the excessive regenerative voltage of the motor 122.

Further, according to the present embodiment, since a circuit component for absorbing the regenerative voltage such as a braking resistor for protecting the circuit from an excessive regenerative voltage is not required, the circuit configuration of the second drive circuit 52 is simplified. And the cost of parts can be reduced.

Further, when an excessive regenerative voltage is generated in the motor 122, the excess power in the second drive circuit 52 can be supplied to the first drive circuit 51 via the energizing line 541, so that the motor 122 can be driven. It is possible to quickly return from the regenerative mode to the power running mode (time t2 in FIG. 9). As a result, the stop period of the pumping action in the second vacuum pump 120 is shortened, and the pulse pressure vibration of the gas that can be generated in the second vacuum pump 120 can be reduced.

The control unit 53 calculates the elapsed time of the switch circuit 542 in the on state, and after the predetermined time elapses, returns the switch circuit 542 to the off state (steps 203 and 204). As a result, the electrical continuity between the first drive circuit 51 and the second drive circuit 52 is cut off, and the individual operation control of the first vacuum pump 110 and the second vacuum pump 120 is restarted. The predetermined time is not particularly limited, and is typically set to a time sufficient to eliminate the excessive regenerative voltage generated by the motor 122. Further, it is preferable that the control unit 53 monitors the regenerative voltage and turns off the switch circuit 542 when the voltage is equal to or lower than the withstand voltage of the semiconductor switching element Tr of the inverter circuit unit 5c. After that, the above-mentioned process is repeatedly executed.

In addition, in this embodiment as well, the same action and effect as in the first embodiment can be obtained. That is, the control unit 53 monitors not only the circuit voltage of the second drive circuit 52 but also the circuit voltage of the first drive circuit 51, so that the switch circuit 542 is turned on when the internal pressure of the vacuum chamber 1 suddenly rises. The first drive circuit 51 can be protected from the excessive regenerative voltage of the motor 112.

<Third embodiment>
Subsequently, a third embodiment of the present invention will be described. As shown in FIG. 2, the vacuum exhaust device 300 of the present embodiment is first and second in that it includes a first vacuum pump 110, a second vacuum pump 120 located in a subsequent stage, and a controller 130. However, the configuration of the control unit 53 is different from that of the first and second embodiments.

The control unit 53 of the present embodiment adds to or instead monitors the regenerative voltage of the motors 112 and 122 in the first drive circuit 51 and the second drive circuit 52, and the first drive circuit 51 and the second drive circuit 51 and the second. It has a function of monitoring the presence or absence of an instantaneous power failure (instantaneous voltage drop) of the AC power supply 60 connected to the drive circuit 52 of the above. Then, when the control unit 53 detects a momentary power failure of the AC power supply 60, the control unit 53 switches the switch circuit 542 in the power supply unit 54 to the ON state, and electrically connects the first drive circuit 51 and the second drive circuit 52. It is configured to connect to.

FIG. 11 is a flowchart illustrating an operation method of the vacuum exhaust device 300 executed by the control unit 53. The control unit 53 monitors the presence or absence of a momentary power failure during the operation of the vacuum exhaust device 300, and when the occurrence of a momentary power failure is detected, the control circuit 53 switches the switch circuit 542 from the off state to the on state, whereby the first The drive circuit 51 and the second drive circuit 52 are electrically connected (steps 301 and 302).

When a momentary power failure occurs, the first drive circuit 51 cannot generate a motor drive current, so that the torque of the motor 112 changes from power running to regeneration. The magnitude of the regenerative voltage is determined by the number of rotations of the pump rotor R1 when a momentary power failure occurs, and the rotational energy due to the inertia of the pump rotor R1 is converted into the regenerative voltage.

On the other hand, in the second drive circuit 52, the regenerative voltage of the motor 112 is supplied from the first drive circuit 51 to the second drive circuit 52 via the energizing line 541 by switching the switch circuit 542 to the ON state. To. As a result, the second vacuum pump 120 continues the pumping operation as long as the electric power required for driving the motor 122 is supplied from the first drive circuit 51 to the second drive circuit 52, and the vacuum of the vacuum chamber 1 is vacuumed. It is possible to suppress the decrease in degree.

In this case, the life extension time (time until the pump operation stops) of the second vacuum pump 120 is ideally the time required for the power to be restored, and when an auxiliary power supply (backup power supply) is provided, the time is ideal. It is preferable that the time is longer than the time from the occurrence of the momentary power failure to the operation of the auxiliary power supply. For this reason, the capacitor C1 in the first drive circuit 51 is preferably composed of an element having a larger capacity than the capacitor C2 in the second drive circuit 52.

In this embodiment, the switch circuit 542 may be composed of a normal-on (B contact) switch. This eliminates the need for electric power to keep the switch circuit 542 in the on state, so that the life extension time of the second vacuum pump 120 can be extended to the maximum. In addition, the switch circuit 542 can be quickly switched to the ON state in the event of a power failure.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and it goes without saying that various modifications can be made.

For example, in the above embodiments, a mechanical booster pump is used as the first vacuum pump 110, and a screw pump is used as the second vacuum pump 120. However, the present invention is not limited to this, and other vacuum pumps such as roots pumps and scroll pumps are used. Can be adopted.

Further, in the above embodiment, the switch circuit 542 in the power supply unit 54 can be switched from the off state to the on state (or from the on state to the off state) based on the instruction of the control unit 53, but this is limited to this. I can't. For example, the switch circuit 542 may employ a switching element that automatically switches to the ON state when the circuit voltage is equal to or higher than a predetermined value.

The configuration of the vacuum exhaust device is not limited to the above example, and for example, the gas from the exhaust port of the first vacuum pump 110 to the atmosphere in parallel with the second vacuum pump 120 in the subsequent stage of the first vacuum pump 110. A check valve with a forward flow of the above may be connected.

1 ... Vacuum chamber 51 ... First drive circuit 52 ... Second drive circuit 53 ... Control unit 54 ... Power supply unit 100, 200, 300 ... Vacuum exhaust device 110 ... First vacuum pump 112, 122 ... Motor 120 ... Second vacuum pump 130 ... Controller 541 ... Energizing line 542 ... Switch circuit

Claims (8)

A first pump body having a first motor, a first vacuum pump having a first drive circuit for driving the first motor, and a first vacuum pump.
A second vacuum pump having a second motor and connected to the rear stage of the first pump body, and a second vacuum pump having a second drive circuit for driving the second motor.
A vacuum exhaust device including a power supply unit having an energizing line that can electrically connect between the first drive circuit and the second drive circuit. The vacuum exhaust device according to claim 1.
The first drive circuit and the second drive circuit are vacuum exhaust having a rectifying circuit unit that rectifies an alternating current, a smoothing circuit unit that includes a smoothing capacitor, and an inverter circuit unit that generates a motor drive current. apparatus. The vacuum exhaust device according to claim 1 or 2.
The power supply unit further includes a switch circuit capable of switching between electrical connection between the first drive circuit and the second drive circuit and disconnection thereof. The vacuum exhaust device according to claim 3.
A vacuum exhaust device further comprising a control unit that controls switching of the switch circuit. The vacuum exhaust device according to claim 4.
When the regenerative voltage in the first drive circuit and / or the second drive circuit is equal to or higher than a predetermined value, the control unit electrically connects the first drive circuit and the second drive circuit. A vacuum exhaust device that controls the switch circuit so as to be connected to. The vacuum exhaust device according to claim 4 or 5.
The control unit is such that when the power supply of the first drive circuit and the second drive circuit is stopped, the first drive circuit and the second drive circuit are electrically connected to each other. A vacuum exhaust device that controls the switch circuit. The vacuum exhaust device according to any one of claims 1 to 5.
The first vacuum pump is a single-stage mechanical booster pump.
The second vacuum pump is a vacuum exhaust device which is a multi-stage dry pump. Driving the first vacuum pump and the second vacuum pump connected to the subsequent stage of the first vacuum pump,
When the motor of the first vacuum pump generates a regenerative voltage, the energization line connected between the drive circuit of the first vacuum pump and the drive circuit of the second vacuum pump is used. The regenerative voltage is supplied to the drive circuit of the second vacuum pump,
A method of operating a vacuum exhaust device that supplies a regenerative voltage to a drive circuit of the first vacuum pump via the energizing line when the motor of the second vacuum pump generates a regenerative voltage.

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