JP2022167582A - Vacuum pump and control method for vacuum pump - Google Patents

Abstract

To provide a vacuum pump that can shorten stopping time through stable operation.SOLUTION: A vacuum pump comprises a vacuum pump body, a load generation part, and a control part. The vacuum pump body comprises a rotor, and a motor. The motor drives the rotor. The load generation part can generate a load for decelerating the motor by being supplied with regenerative electric power of the motor. The control part performs control so that the regenerative electric power supplied to the load generation part is gradually increased.SELECTED DRAWING: Figure 5

Description

The present invention relates to a vacuum pump and a vacuum pump control method.

2. Description of the Related Art In the field of semiconductor manufacturing equipment and the like, a turbomolecular pump, which is a type of vacuum pump, is used to create a high-vacuum atmosphere (see, for example, Patent Document 1).

The turbo-molecular pump disclosed in Patent Document 1 includes a vacuum pump main body having a rotor, a motor section for driving the rotor, and a casing for housing the rotor and the motor section, and a control device for controlling the drive of the motor section. .

Small turbomolecular pumps are often installed in vacuum devices that can be carried and moved, and there is a demand for such devices to be moved to the next place of use as soon as the power is turned off after use. Since a turbomolecular pump may require one hour from rated operation to stop, the load on the motor is increased to hasten deceleration. For example, an electromagnetic valve is used to allow air to flow in during deceleration of the turbomolecular pump, thereby increasing the load on the motor and accelerating the deceleration. Also, the load on the motor is increased by converting the regenerated electric power into heat energy using a brake resistance.

JP 2020-153367 A

When the power supply to the device is turned off, the power supply to the turbo molecular pump is cut off, so the turbo molecular pump switches from power running to regenerative driving, and deceleration is performed while power is supplied to the motor control circuit from regenerative power. .
Since the device is powered off, the regenerative power is used to open the solenoid valve described above, but the regenerative power load may change suddenly when the solenoid valve is opened. As a result, the regenerated power becomes insufficient, and the control circuit may not operate.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a vacuum pump and a vacuum pump control method capable of shortening the stop time with stable operation.

A vacuum pump according to an aspect of the present invention includes a vacuum pump body, a load generator, and a controller. The vacuum pump body has a rotor and a motor. A motor drives the rotor. The load generator can generate a load for decelerating the motor by supplying regenerated electric power of the motor. The control unit controls to gradually increase the regenerative power supplied to the load generation unit.

A vacuum pump control method according to another aspect of the present invention includes a detection step and a power supply step. The detection step detects the interruption of power supply to the vacuum pump. In the power supply step, a load for decelerating the motor is generated by supplying power from regenerative power generated by regenerative driving of the motor that drives the rotor of the vacuum pump after the stop of the power supply is detected. Gradually increase the power supplied to the unit.

According to the aspects of the present invention described above, it is possible to provide a vacuum pump and a control method of the vacuum pump that can shorten the stop time with stable operation.

1 is an external view of a vacuum pump according to an embodiment; FIG. It is a sectional view of a vacuum pump concerning an embodiment. It is a figure which shows the control circuit provided in the vacuum pump which concerns on embodiment. It is a figure which shows the functional block of the controller provided in the vacuum pump which concerns on embodiment. It is a figure which shows typically an example of the PWM signal which concerns on embodiment. 4 is a diagram showing the relationship between the PPWM output and the current supplied to the bending valve according to the embodiment; FIG. It is a figure which shows the change of the motor voltage at the time of performing the PWM output which concerns on embodiment. FIG. 4 is a diagram showing changes in PWM output when the motor voltage fluctuates from the target value due to load changes according to the embodiment; It is a flow chart showing a control method of the vacuum pump according to the embodiment. It is a figure which shows the control circuit of the vacuum pump which concerns on the modification of embodiment. FIG. 10 is a diagram showing the relationship between the PPWM output and the current supplied to the bending valve according to the modified example of the embodiment; FIG. 5 is a graph showing changes in motor voltage when decelerating while obtaining regenerative electric power; FIG. 5 is a graph showing changes in motor voltage when a load suddenly changes while obtaining regenerative power;

When the power supply to the device is turned off, the power supply to the turbo molecular pump is cut off, so the turbo molecular pump switches from power running to regenerative driving, and deceleration is performed while power is supplied to the motor control circuit from regenerative power. . FIG. 12 is a graph showing changes in motor voltage when decelerating while obtaining regenerative electric power. The horizontal axis of FIG. 12 indicates time (s), and the vertical axis indicates motor voltage (v). When the power supply is turned off at time t1 and the power supply to the turbomolecular pump is stopped, the power supply stoppage is detected at time t2 and the drive is switched to regenerative driving. When taking out the regenerated electric power, the motor is controlled so that the motor voltage is kept constant.

Since the device is powered off, the regenerative power is used to open the solenoid valve described above, but the regenerative power load may change suddenly when the solenoid valve is opened. FIG. 13 is a diagram showing a graph of changes in motor voltage when the load suddenly changes while the regenerative power is being obtained. The horizontal axis of FIG. 13 indicates time (s), and the vertical axis indicates motor voltage (v). When the on-off valve is opened at time t3 after time t2, the regenerated electric power becomes insufficient as shown at time t3 to time t4, the control circuit stops operating, and the voltage after time t4 becomes the back electromotive voltage as it is. Sometimes. The same is true when regenerative power is supplied to the brake resistor, and the consumption of regenerative power may suddenly change, causing the control circuit to stop operating.

The present invention solves such problems, and a vacuum pump according to one embodiment will be described below with reference to the drawings.

(Overview of configuration of vacuum pump)
FIG. 1 is an external view of a vacuum pump 1 according to an embodiment.

The vacuum pump 1 of this embodiment includes a turbomolecular pump and a thread groove pump. The vacuum pump 1 is connected to an evacuation target device including an evacuation target space. The gas from the space to be evacuated is evacuated by the turbo-molecular pump, then evacuated by the screw groove pump, and is evacuated to the outside of the vacuum pump 1 .

The vacuum pump 1 includes a vacuum pump body 2 , a bending valve 3 (load generator, electromagnetic valve), and a control device 4 . The vacuum pump body 2 sucks gas from the space to be evacuated and discharges it to the outside. A bending valve 3 is attached to the vacuum pump body 2 . When the rotation of the rotor 12 (described later) of the vacuum pump main body 2 is stopped, the bending valve 3 is opened to allow air to flow into the vacuum pump main body 2 . The control device 4 controls rotation of a motor 13 (described later) of the vacuum pump body 2 . A control device 4 controls opening and closing of the bending valve 3 .

(Vacuum pump body 2)
FIG. 2 is a cross-sectional view of the vacuum pump main body 2. As shown in FIG. As shown in FIG. 2, the vacuum pump main body 2 has a housing 11, a rotor 12, a motor 13, a plurality of stator blade units 14, and a stator cylindrical portion 15.

(Case 11)
The housing 11 has a casing 21 and a base 22 . The casing 21 and the base 22 are made of metal such as aluminum alloy or iron. The casing 21 is a tubular member having a flange portion at one end.

The casing 21 accommodates a plurality of stator blade units 14 and a plurality of stages of rotor blade units 32 provided on the rotor 12 . Casing 21 includes a first end 23 , a second end 24 , a side portion 25 and a valve port 26 . The first end 23 forms a flange. The first end portion 23 is provided with an intake port 23a. An evacuation target device is connected to the first end portion 23 . The second end 24 is located on the opposite side of the first end 23 in the axial direction A<b>1 of the rotor 12 . A second end 24 is connected to the base 22 . The side portion 25 connects the first end portion 23 and the second end portion 24 . A valve port 26 connected to the bending valve 3 is provided on the side portion 25 . A first internal space S1 is formed inside the casing 21 . The valve port 26 is formed with a communication port 26 a that communicates with the first internal space S<b>1 formed inside the casing 21 and the bending valve 3 . The first internal space S1 communicates with the intake port 23a.

The base 22 is arranged to close the opening of the casing 21 on the second end 24 side. Base 22 includes a base end 27 and an exhaust port 28 . The base end 27 is connected to the second end 24 of the casing 21 . The stator cylindrical portion 15 and the rotor cylindrical portion 33 provided in the rotor 12 are housed in the base 22 and the casing 21 . A second internal space S2 is formed inside the base 22 and the casing 21 . The second internal space S2 communicates with the first internal space S1 of the casing 21 . The exhaust port 28 is provided on the side surface of the base 22 . An exhaust port 28a is formed in the exhaust port 28, and the exhaust port 28a communicates with the second internal space S2.

Gas (gas molecules) that has flowed into the vacuum pump main body 2 from the evacuation target space enters the first internal space S1 through the intake port 23a. The gas reaches the second internal space S2 from the first internal space S1. The gas is discharged from the second internal space S2 to the outside of the vacuum pump main body 2 via the exhaust port 28a.

(Rotor 12)
The rotor 12 has a shaft 31 , multiple stages of rotor blade units 32 , and a rotor cylindrical portion 33 .

The shaft 31 extends in the axial direction A<b>1 of the rotor 12 . In the following description, in the axial direction A1, the direction from the casing 21 to the base 22 is defined as downward, and the opposite direction is defined as upward.

The vacuum pump body 2 further comprises ball bearings 16 , touchdown bearings 17 and permanent magnet magnetic bearings 18 . A ball bearing 16 , a touchdown bearing 17 and a permanent magnet magnetic bearing 18 rotatably support the rotor 12 to the housing 11 . A ball bearing 16 is attached to the base 22 . The touchdown bearing 17 is attached to the casing 21 . The permanent magnet magnetic bearing 18 has permanent magnets 18a, 18b. Permanent magnet 18 a is attached to casing 21 . Permanent magnet 18 b is attached to shaft 31 . The permanent magnet 18b is arranged radially outside the permanent magnet 18a so as to face the permanent magnet 18a.

A plurality of stages of rotor blade units 32 are connected to the shaft 31 respectively. The multiple stages of rotor blade units 32 are spaced apart from each other in the axial direction A1. Each rotor blade unit 32 includes a plurality of rotor blades 34 . Although not shown, each of the plurality of rotor blades 34 radially extends around the shaft 31 . In the drawings, only one of the plurality of stages of rotor blade units 32 and one of the plurality of rotor blades 34 are denoted by reference numerals, and the other rotor blade units 32 and other rotor blades 34 are denoted by reference numerals. omitted.

The rotor cylindrical portion 33 is connected to the shaft 31 . The rotor cylindrical portion 33 is arranged below the rotor blade unit 32 . The rotor cylindrical portion 33 extends in the axial direction A1. The rotor cylindrical portion 33 is arranged so as to surround the shaft 31 on the outer peripheral side of the shaft 31 . The rotor cylindrical portion 33 has a cylindrical outer rotor cylindrical portion 33a and a cylindrical inner rotor cylindrical portion 33b. The outer rotor cylindrical portion 33a is arranged radially outward of the inner rotor cylindrical portion 33b. The shaft 31, the inner rotor cylindrical portion 33b, and the outer rotor cylindrical portion 33a are arranged radially outward in this order.

(Motor 13)
The motor 13 rotationally drives the rotor 12 . A DC brushless motor, for example, is used as the motor 13 . The motor 13 has a motor rotor 35 and a motor stator 36 . A motor rotor 35 is attached to the shaft 31 . A motor stator 36 is attached to the base 22 . The motor stator 36 is arranged to face the motor rotor 35 .

(Multi-stage stator blade unit 14)
The multiple stages of stator blade units 14 are connected to the inner surface of the casing 21 . The multiple stages of stator vane units 14 are arranged at intervals in the axial direction A1. Each of the multiple stages of stator blade units 14 is arranged between multiple stages of rotor blade units 32 . Each stator vane unit 14 includes a plurality of stator vanes 37 . Although not shown, the plurality of stator blades 37 radially extend around the shaft 31 .

The multiple stages of rotor blade units 32 and the multiple stages of stator blade units 14 constitute a turbomolecular pump. In the drawings, only one of the plurality of stator blade units 14 and one of the plurality of stator blades 37 are given reference numerals, and the reference numerals of the other stator blade units 14 and other stator blades 37 are omitted. It is

(Stator cylindrical portion 15)
The stator cylindrical portion 15 has an outer stator cylindrical portion 15a and an inner stator cylindrical portion 15b. The outer stator cylindrical portion 15a is attached to the casing 21 or the base 22. As shown in FIG. The inner stator cylindrical portion 15 b is attached to the base 22 . The outer stator cylindrical portion 15a and the inner stator cylindrical portion 15b are cylindrical and formed along the axial direction A1. The inner stator cylindrical portion 15 b is arranged radially outward of the shaft 31 . The outer stator cylindrical portion 15a is arranged outside the inner stator cylindrical portion 15b.

An outer rotor cylindrical portion 33a is arranged between the outer stator cylindrical portion 15a and the inner stator cylindrical portion 15b. The inner rotor cylindrical portion 33b is arranged radially inward of the inner stator cylindrical portion 15b. A threaded groove (not shown) is formed in one of the inner peripheral side surface of the outer stator cylindrical portion 15a and the outer peripheral side surface of the outer rotor cylindrical portion 33a. A threaded groove (not shown) is formed in one of the inner peripheral side surface of the inner stator cylindrical portion 15b and the outer peripheral side surface of the inner rotor cylindrical portion 33b. The stator cylinder 15 and the rotor cylinder 33 form a threaded pump.

(Bending valve 3)
The bending valve 3 is attached to the side surface of the vacuum pump body 2, as shown in FIG. The bending valve 3 is connected to the valve port 26 shown in FIG. The bending valve 3 is, for example, a solenoid valve. The bending valve 3 is closed when not energized, and is opened when a predetermined voltage is energized.

When the bending valve 3 is open, the internal space (the first internal space S1 and the second internal space S2) of the vacuum pump body 2 communicates with the outside. When the driving of the vacuum pump body 2 is stopped, the air flows into the internal space of the vacuum pump body 2 by opening the bending valve 3 . As a result, a load is applied to the rotation of the rotor 12, and the motor 13 can be decelerated quickly.

(control device 4)
The control device 4 is attached to the lower side of one side surface of the housing 11, as shown in FIG. The control device 4 has a control panel 41 and a control circuit 42 . FIG. 3 is a diagram showing the control circuit 42 provided in the control device 4. As shown in FIG.

The control panel 41 is operated by the user. The control panel 41 has a button 41a for driving and stopping the motor 13, a lamp 41b for indicating the state of the motor 13, and the like. The control device 4 may be provided with a terminal that can be connected to a personal computer or the like so that various settings can be made from the personal computer.

A control circuit 42 controls the motor 13 and the bending valve 3 . The control circuit 42 includes an interface connector (hereinafter referred to as an IF connector) 43, a valve connector 44 (shown as CN in FIG. 3), a cable 45, bus lines 46a and 46b, a DC/DC converter 47, and a three-phase inverter circuit 48. , a switching element 49 (power change unit), a diode 50, a first voltage sensor 51 (voltage detection unit), a second voltage sensor 52 (power detection unit), and a rotation speed detection unit 53 (described later in FIG. 4 ) and a controller 54 (control unit).

DC power of, for example, 24 V is input to the IF connector 43 from a DC power supply. Power is supplied to the motor 13 and the controller 54 via the IF connector 43 . The IF connector 43 may be provided with a switch for supplying and cutting off power. A switch for supplying and cutting off power may be provided between the IF connector 43 and the DC power supply, or between the DC power supply and the commercial AC power supply.

The valve connector 44 is provided on the side of the control device 4, as shown in FIG. One end of a cable 45 (not shown in FIG. 1) connected to the bending valve 3 is connected to the valve connector 44 as shown in FIG. The other end of cable 45 is connected to bending valve 3 .

The bus line 46a is connected to the 24V side through the IF connector 43. As shown in FIG. The bus 46b is connected to the ground via the IF connector 43. As shown in FIG. Also, the busbars 46 a and 46 b are connected to the valve connector 44 .

The DC/DC converter 47 is connected to two buses 46a, 46b. 24V DC power is supplied to the DC/DC converter 47 via the IF connector 43 . The DC/DC converter 47 converts the voltage of the supplied DC power and supplies it to the controller 54 . Also, the DC/DC converter 47 converts the voltage of the regenerated electric power generated by the motor 13 during regenerative operation and supplies it to the controller 54 .

The three-phase inverter circuit 48 uses power supplied through the IF connector 43 to rotationally drive the motor 13 . The three-phase inverter circuit 48 has a plurality of switching elements 48a-48f connected to a bus 46a or 46b. Transistors, for example, are used for these switching elements 48a to 48f. The three-phase inverter circuit 48 is configured by connecting switching elements 48a to 48f in a three-phase bridge connection, and the output terminals of the phases are connected to the phase windings of the motor 13, respectively. A PWM (Pulse Width Modulation) signal from a controller 54 is input to the base of each of the switching elements 48a to 48f, and the switching elements 48a to 48f are controlled to open and close, thereby supplying power to the motor 13. Rotate. Note that signal lines from the controller 54 to the switching elements 48a to 48f and a switching element 49 (to be described later) are indicated by dotted lines for the sake of clarity.

Further, when the vacuum pump main body 2 is stopped by shutting off the power from the outside, the motor 13 is regeneratively driven to generate regenerative power. The regenerated power is supplied to controller 54 via DC/DC converter 47 . The controller 54 uses the supplied electric power to control the three-phase inverter circuit 48 to control the rotation of the motor 13 . The regenerated electric power generated by the motor 13 is supplied to the bending valve 3 when the switching element 49 is in the open state.

The switching element 49 is arranged on the bus 46 b between the three-phase inverter circuit 48 and the valve connector 44 . The switching element 49 connects the bus 46b in the open state, and disconnects the bus 46b in the closed state. A transistor, for example, is used for the switching element 49 . A PWM signal from the controller 54 is input to the base of the switching element 49 . The switching element 49 opens and closes according to the input PWM signal.

For example, when power is being supplied from the outside, the switching element 49 is opened and closed to supply or cut off power from the external power to the bending valve 3 . When the motor 13 is generating regenerative electric power, the switching element 49 is opened and closed to supply or cut off electric power from the regenerative electric power to the bending valve 3 .

The diode 50 is arranged between the connecting point of the bus 46 a to the DC/DC converter 47 and the IF connector 43 . Diode 50 is provided to prevent backflow of regenerated electric power generated in motor 13 to external electric power.

A first voltage sensor 51 is arranged between the IF connector 43 and the diode 50 on the bus 46a. The first voltage sensor 51 detects the voltage supplied from the external power and outputs the detected value to the controller 54 .

The second voltage sensor 52 is arranged between the connection point between the diode 50 and the DC/DC converter 47 on the bus 46a. The second voltage sensor 52 detects the voltage of the regenerated electric power generated by the motor 13 during regenerative driving, and outputs the detected value to the controller 54 .

A rotation speed detection unit 53 shown in FIG. 4 to be described later detects or calculates the rotation speed of the rotor 12 . The rotational speed detector 53 outputs the detected value to the controller 54 .

Controller 54 includes a processor and a memory device. The processor is, for example, a CPU (Central Processing Unit). Alternatively, the processor may be a processor different from the CPU. The processor executes processing for controlling the vacuum pump 1 according to the program. The storage device includes non-volatile memory such as ROM (Read Only Memory) and volatile memory such as RAM (Random Access Memory). The storage device may include a hard disk or an auxiliary storage device such as an SSD (Solid State Drive). A storage device is an example of a non-transitory computer-readable recording medium. The storage device stores programs and data for controlling the vacuum pump 1 . The storage device stores, for example, data of a threshold value and a target voltage value of the motor, which will be described later.

Controller 54 controls switching elements 48 a - 48 f and switching element 49 .

FIG. 4 is a diagram showing functional blocks of the controller 54. As shown in FIG.

The controller 54 has a power failure detection unit 61 , a motor voltage detection unit 62 , a motor PWM signal output unit 63 , and a valve PWM signal output unit 64 .

The power failure detection unit 61 acquires the detection value of the first voltage sensor 51 and detects whether or not the power supply from the external power source has stopped. For example, the threshold is stored in the storage device described above. The power failure detection unit 61 compares the detection value of the first voltage sensor 51 with the threshold value, and detects that the supply of power from the external power source has stopped (power off) when the detection value is smaller than the threshold value.

The motor voltage detection unit 62 acquires the detection value of the second voltage sensor 52 and detects whether the regenerated voltage from the motor 13 during regenerative driving has become higher or lower than the target motor voltage. . For example, the target value of the motor voltage is stored in the storage device described above. The motor voltage detector 62 detects whether the detected value of the second voltage sensor 52 is higher or lower than the target value.

The motor PWM signal output unit 63 outputs PWM signals for driving the motor 13 to the switching elements 48 a to 48 f of the three-phase inverter circuit 48 . The rotation of the motor 13 is controlled by opening and closing each of the switching elements 48a to 48f based on the PWM signal.

The motor PWM signal output unit 63 selects the motor 13 suitable for sucking gas from the exhaust target space based on the detection value of the rotation speed detection unit 53 during power running in which power is supplied from an external power supply. A PWM signal is output to the three-phase inverter circuit 48 using power from an external power supply so as to achieve the target rotation speed.

In addition, the motor PWM signal output unit 63 is suitable for taking out regenerative power based on the detection values of the second voltage sensor 52 and the rotation speed detection unit 53 during regenerative driving when the power from the external power supply is stopped. A PWM signal is output to the three-phase inverter circuit 48 using the regenerated electric power generated by the motor 13 so that the target rotation speed and the target voltage value of the motor 13 are obtained.

When the power failure detection unit 61 detects that the external power supply is stopped, the valve PWM signal output unit 64 gradually increases the duty ratio, which is the ratio of the pulse width to the period, from 0 to 100%. A PWM signal is output to the switching element 49 as follows. An increase in duty ratio from 0 to 100% can be performed, for example, in about 1 second.

FIG. 5 is a diagram schematically showing an example of a PWM signal whose duty ratio is set to gradually increase. In FIG. 5, the horizontal axis indicates time (s) and the vertical axis indicates voltage (V). Let the cycle be Tc and the width of one pulse be Tp. The duty ratio can be represented by Tp/Tc×100(%). Also, the voltage of the pulse is indicated by Vp. The PWM signal shown in FIG. 5 is set so that the duty ratio increases every predetermined time Td. In FIG. 5, for the sake of clarity, predetermined times Td(1), Td(2), . The pulse widths are also numbered Tp(1), Tp(2), . . . Tp(n). In order to make the drawing easier to understand, the cycle Tc in each predetermined time Td is shown as four cycles.

Specifically, during the first predetermined time Td(1), the duty ratio is set to 0 (zero) and no pulse is generated. Although not shown, the pulse width Tp(1) is set to zero.

In the second predetermined time Td(2), a pulse with a pulse width Tp(2) is output for each cycle. At the third predetermined time Td(3), a pulse with a pulse width Tp(3) longer than the second pulse width Tp(2) is output. At the fourth predetermined time Td(4), a pulse with a pulse width Tp(4) longer than the third pulse width Tp(3) is output. In this way, a pulse signal with a gradually increasing duty ratio is output, and finally the duty ratio reaches 100%. In FIG. 5, the pulse width Tp(n) becomes the same time width as the period Tc in the predetermined time Td(n), and a signal with a duty ratio of 100% is output.

Note that the duty ratio may be changed from 0% to 100% by, for example, increasing the duty ratio for each cycle without being limited to the example of FIG.

FIG. 6 is a diagram showing the relationship between the PWM output and the current supplied to the bending valve 3. As shown in FIG. In FIG. 6, the horizontal axis indicates time (s), and power supply is stopped (power is cut off) at time 0 (s) (zero). The vertical axis on the left indicates PWM output (%). PWM output (%) is a duty ratio. The change in PWM output is indicated by the solid line. The vertical axis on the right side indicates the average value (A) of the current supplied to the bending valve 3 . The change in the average value of the current supplied to the bending valve 3 is indicated by the dashed line. As shown in FIG. 6, when the output of the PWM signal is gradually increased after a power failure, the current supplied to the bending valve 3 gradually increases, so a sudden change in load does not occur. The duty ratio of the PWM signal may increase linearly with time as shown in FIG. 6, but may also increase exponentially. Gradually increasing the power supplied to the bending valve 3 from the regenerated power means increasing the power at a rate capable of suppressing a sudden change in the consumption of the regenerated power.

FIG. 7 is a diagram showing changes in motor voltage when PWM output as shown in FIGS. 5 and 6 is performed. The horizontal axis of FIG. 7 indicates time (s), and the vertical axis indicates motor voltage (V). Power supply to the vacuum pump 1 is stopped at time t1. Then, at time t2, the power failure detection unit 61 detects the stop of the power supply. In the graph shown in FIG. 7, compared to FIG. 13, the power supplied to the bending valve 3 by the PWM signal gradually increases, and the bending valve 3 opens at time t5. Since the load gradually increases in this way, the motor can be driven by the regenerative power without causing a shortage of the regenerative power. be able to.

By gradually increasing the duty ratio of the PWM signal in this way, the pulse width with respect to the cycle is increased, and the open state of the switching element 49 during the predetermined time Td is lengthened. Therefore, the applied voltage supplied to the bending valve 3 from the regenerated power generated by the motor 13 gradually increases, and when the voltage exceeds a predetermined voltage, the bending valve 3 is opened. As a result, when the power supply from the external power source is stopped, the regenerated power generated by the motor 13 can be used to open the bending valve 3 to supply air to the vacuum pump main body 2 . In addition, since the power supplied to the bending valve 3 from the regenerated power is gradually increased, the bending valve 3 can be opened while suppressing a sudden change in the consumption of the regenerated power.

Note that when power is supplied from the outside, there is no need to consider a sudden change in power consumption due to driving the bending valve 3 to the open state. A signal with a ratio of 100% may be output to the switching element 49 .

The valve PWM signal output section 64 changes the duty ratio of the PWM signal based on the detection by the motor voltage detection section 62 . FIG. 8 is a diagram showing changes in the PWM output when the motor voltage fluctuates from the target value due to load changes. The horizontal axis of FIG. 8 indicates time (s). The vertical axis on the left side of FIG. 8 indicates the motor voltage (v). The change in motor voltage is indicated by the solid line. The vertical axis on the right side of FIG. 8 indicates the PWM output. The change in PWM output is indicated by the dashed line. At time 0, power supply to the vacuum pump body 2 is stopped. Assuming that the target value of the motor voltage is Vt, the motor voltage reaches Vt at time t6 in FIG. 7, but does not reach Vt in FIG. Therefore, it is detected that the motor voltage is lower than the target value, and the PWM signal is changed so as to reduce the output of the PWM signal (reduce the duty ratio). As a result, the power supplied to the bending valve 3 is reduced and the motor voltage can be increased. Therefore, the motor voltage reaches the target value Vt at time t7. Also, at time t8, when it is detected that the motor voltage is higher than the target value, the PWM signal is changed so as to increase the output of the PWM signal (increase the duty ratio). As a result, the power supplied to the bending valve 3 is increased, and the motor voltage can be lowered. Therefore, the motor voltage returns to the target value Vt at time t9.

The PWM output is changed according to the deviation between the motor voltage target value Vt and the current motor voltage value. That is, when the deviation is large, the PWM output is greatly changed, and when the deviation is small, the change of the PWM output is made small.

(Control method)
Next, a method for controlling the vacuum pump 1 of this embodiment will be described. The control method of the vacuum pump 1 of this embodiment is performed when the vacuum pump 1 is stopped.

FIG. 9 is a flow chart showing a control method of the vacuum pump 1 of this embodiment.

First, in step S10 (detection step), the power failure detection unit 61 determines whether or not the power supply from the outside has stopped based on the detection value of the first voltage sensor 51 . Step S10 is repeated until the power failure detection unit 61 determines that the power supply from the outside has stopped. When the power failure detection unit 61 detects that the power supply from the outside has stopped, the control proceeds to step S20. The supply of power from the outside may be stopped by turning off the control circuit 42 or by providing a switch between the control circuit 42 and the commercial power supply, or by disconnecting the commercial power supply. Disconnecting from the commercial power supply means, for example, unplugging from the commercial power supply.

In step S20, the valve PWM signal output unit 64 starts outputting to the switching element 49 a PWM signal that gradually increases the duty ratio from 0%. The duty ratio may be increased, for example, by a predetermined amount or rate of increase every predetermined time (see FIG. 5).

Next, in step S30, after the duty ratio of the PWM signal has increased to 100%, the valve PWM signal output unit 64 determines whether or not the output of the PWM signal has ended after a predetermined time has elapsed. Steps S20 and S30 correspond to the power supply step.

If the output of the PWM signal has not ended, control proceeds to step S40.

Then, in step S40, the motor voltage detection unit 62 determines whether or not the motor voltage is at the target value based on the detection value of the second voltage sensor 52. If it is detected that the motor voltage is not at the target value, control proceeds to step S50.

In step S<b>50 , the valve PWM signal output section 64 changes the PWM signal based on the detection result of the motor voltage detection section 62 . For example, when the motor voltage detection unit 62 detects that the motor voltage is higher than the target value, the valve PWM signal output unit 64 outputs the duty ratio at a predetermined increase amount or increase rate. output a PWM signal with a duty ratio greater than As a result, the power supplied to the bending valve 3 is increased, so that the consumption of regenerated power can be increased and the motor voltage can be lowered. Further, for example, when the motor voltage detection unit 62 detects that the motor voltage is lower than the target value, the valve PWM signal output unit 64 outputs a predetermined increase amount or increase rate. A PWM signal with a duty ratio smaller than the duty ratio is output. As a result, less power is supplied to the bending valve 3, so that the consumption of regenerated power can be reduced and the motor voltage can be increased.

Control then returns to step S30 to determine whether or not the output of the PWM signal has ended. If it is determined in step S40 that the motor voltage is at the target value, the control also returns to step S30.

Therefore, steps S40 and S50 are repeated until it is determined in step S30 that the output of the PWM signal has ended.

If it is determined in step S30 that the output of the PWM signal has ended, the control ends.

(Other embodiments)
Although one embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment, and various modifications are possible without departing from the gist of the invention.

In the above-described embodiment, the bending valve 3 is used as an example of the load generating unit when the vacuum pump 1 is stopped. For example, along with the bending valve 3 or instead of the bending valve 3, a regenerative braking resistance may be provided as an example of a load generation unit.

FIG. 10 is a diagram showing a control circuit 42 having a configuration in which a regenerative brake resistor 55 (brake resistor) is provided in addition to the bending valve 3 as a load generator. As shown in FIG. 10, the regenerative braking resistor 55 is connected to the bus 46a and the bus 46b. A switching element 56 is arranged between the regenerative brake resistor 55 and the bus 46b. With the switching element 56 closed, regenerative power generated by the motor 13 is supplied to the regenerative braking resistor 55 . When the regenerative electric power is supplied to the regenerative braking resistor 55, it is converted into thermal energy. The switching element 56 is a transistor, and the PWM signal from the controller 54 is input to the base. The PWM signal output from the controller 54 is set so that the duty ratio gradually increases, like the PWM signal to the switching element 49 described above. As a result, the power supplied to the regenerative braking resistor 55 from the regenerative power can be gradually increased. A PWM signal may be output from the valve PWM signal output unit 64 to the switching element 56, or a brake PWM signal output unit that outputs the PWM signal to the switching element 56 may be separately provided in the controller 54. .

In the above embodiment, as shown in FIG. 6, PWM output is started as soon as it is detected that the power supply to the vacuum pump 1 has stopped. PWM output may be started after a predetermined delay time has elapsed since detection. FIG. 11 is a graph showing the relationship between the PWM output and the current supplied to the bending valve 3 when the delay time Δt is set. In FIG. 11 , the horizontal axis indicates time (s), and power supply is stopped (power is cut off) at time 0 (s) (zero). The vertical axis on the left indicates PWM output (%). PWM output (%) is a duty ratio. The change in PWM output is indicated by the solid line. The vertical axis on the right side indicates the average value (A) of the current supplied to the bending valve 3 . The change in the average value of the current supplied to the bending valve 3 is indicated by the dashed line. As shown in FIG. 11, the output of the PWM signal is started after a predetermined delay time Δt after the power failure. This delay time Δt may be settable by the user and stored in the memory of the controller 54 .

If there is a risk of damage due to a pressure rise if air flows in while the vacuum pump is turned off, or if there is a risk of damage due to atmospheric components, open the bending valve as soon as the vacuum pump is turned off. may not be desired. In such a case, it is preferable to provide a delay time after the power supply stop is detected, because damage to the sensor device can be reduced.

In the above embodiment, the PWM output is used to increase the power supply to the load generation unit, but it is not limited to PWM, and PDM (Pulse Density Modulation), PFM (Pulse Frequency Modulation) Modulation (Pulse Frequency Modulation), PAM (Pulse Amplitude Modulation), or the like may be used.

Although the target value Vt of the motor voltage is set in the above embodiment, the target value may have a range and an upper limit value and a lower limit value may be provided.
In the above embodiment, the second voltage sensor 52 is used as an example of the power detection unit to detect stoppage of power supply from the outside (power off), but current may be detected instead of voltage. .

Although the controller 54 includes the valve PWM signal output section 64 in the above embodiment, the IF connector 43 may include the valve PWM signal output section 64 .

(mode)
It will be appreciated by those skilled in the art that the multiple exemplary embodiments described above are specific examples of the following aspects.

(First Aspect) A vacuum pump includes a vacuum pump body, a load generator, and a controller. The vacuum pump body has a rotor and a motor. A motor drives the rotor. The load generator can generate a load for decelerating the motor by supplying regenerated electric power of the motor. The controller controls to gradually increase the regenerated power supplied to the load generator.

In the vacuum pump according to the first aspect, the power supplied to the load generator from the regenerated power is gradually increased. As a result, sudden changes in the consumption of regenerated electric power by the load generating section can be suppressed, and the control section can stably operate. Also, a load can be generated that decelerates the motor. Therefore, it is possible to shorten the stop time with stable operation.

(Second Aspect) In the vacuum pump according to the first aspect, the load generator has an electromagnetic valve that supplies air to the inside of the vacuum pump main body in an open state. The control unit controls to gradually increase the regenerative electric power supplied to the solenoid valve to open the solenoid valve.

In the vacuum pump according to the second aspect, the power supplied from the regenerated power to the solenoid valve is gradually increased to open the solenoid valve. As a result, a load can be generated by supplying air to the interior of the vacuum pump main body while suppressing a sudden change in the consumption of regenerative power. Therefore, it is possible to shorten the stop time with stable operation.

(Third Aspect) The vacuum pump according to the first aspect has a brake resistor for converting regenerated electric power into thermal energy. The control unit controls to gradually increase the regenerative electric power supplied to the brake resistor.

In the vacuum pump according to the third aspect, the electric power supplied to the brake resistor from the regenerated electric power is gradually increased. As a result, the load can be generated by converting the regenerative electric power into thermal energy while suppressing a sudden change in consumption of the regenerative electric power. Therefore, it is possible to shorten the stop time with stable operation.

(Fourth Aspect) The vacuum pump according to any one of the first to third aspects supplies regenerative power to the load generating section in the open state, and stops supplying regenerative power to the load generating section in the closed state. have elements. The control unit outputs a pulse signal for opening and closing the switching element, and modulates the pulse signal so as to gradually increase the regenerative power supplied to the load generation unit.

In the vacuum pump according to the fourth aspect, the opening and closing of the switching element can be controlled by outputting the pulse signal, so it is possible to control the amount of power supplied from the regenerative power to the load generation unit.

Also, by modulating the pulse signal, the opening/closing time of the switching element can be controlled. This makes it possible to control the amount of power supplied from the regenerated power to the load generator.

(Fifth Aspect) In the vacuum pump according to the fourth aspect, the controller gradually increases the supply of regenerative power to the load generator by gradually increasing the duty ratio of the pulse width of the pulse signal. .

In the vacuum pump according to the fifth aspect, by outputting to the switching element a pulse signal whose duty ratio is set to gradually increase, the amount of power supplied from the regenerated power to the load generator can be gradually increased. can.

(Sixth Aspect) The vacuum pump according to any one of the first to fifth aspects further comprises a voltage detection section for measuring the voltage of the motor in regenerative driving. The controller changes the regenerated power supplied to the load generator based on the detected value of the voltage detector.

In the vacuum pump according to the sixth aspect, by detecting the voltage of the motor during regenerative driving, it is possible to change the electric power supplied to the load generator so as to achieve the target motor voltage. As a result, for example, when the load is generated slowly, when the load fluctuation causes the motor voltage to become lower than the target motor voltage, or when the load fluctuation causes the motor voltage to become higher than the target motor voltage, the target motor voltage value can be controlled.

(Seventh Aspect) The vacuum pump according to the fourth aspect further comprises a power detection section for detecting information relating to external power supply to the vacuum pump. The control unit controls to gradually increase the regenerative power supplied to the load generation unit when the stop of the power supply from the outside is detected based on the detection by the power detection unit.

In the vacuum pump according to the seventh aspect, it is possible to detect switching to regenerative driving and start outputting the pulse signal to the switching element by detecting the stoppage of the power supply from the outside.

(Eighth Aspect) In the vacuum pump according to the seventh aspect, when the control unit detects stoppage of power supply from the outside based on the detection by the power detection unit, after a predetermined delay time, the load generation unit Control is performed so that the supplied regenerative power is gradually increased.

If there is a possibility of damage to the sensor equipment installed in the equipment to be evacuated due to the pressure increase caused by the inflow of air at the same time when the vacuum pump is turned off, or if there is a possibility of damage due to the components of the atmosphere, the vacuum pump It may not be desirable to open the bending valve at the same time that the power is turned off. In such a case, it is possible to reduce damage to the sensor device by providing a delay time after the power supply stop is detected.

(Ninth Aspect) A vacuum pump control method includes a detection step and a power supply step. The detection step detects the interruption of power supply to the vacuum pump. In the power supply step, a load for decelerating the motor is generated by supplying power from regenerative power generated by regenerative driving of the motor that drives the rotor of the vacuum pump after the stop of the power supply is detected. Gradually increase the power supplied to the unit.

In the vacuum pump control method according to the ninth aspect, the power supplied from the regenerated power to the load generator is gradually increased. This makes it possible to suppress abrupt changes in the consumption of regenerative power and to stably operate the control circuit. Also, a load can be generated that decelerates the motor. Therefore, it is possible to shorten the stop time with stable operation.

1: Vacuum pump, 2: Vacuum pump body, 3: Bending valve, 4: Control device, 11: Housing, 12: Rotor, 13: Motor, 14: Stator blade unit, 15: Stator cylinder, 15a: Outer stator Cylindrical portion 15b: inner stator cylindrical portion 16: ball bearing 17: touchdown bearing 18: permanent magnet magnetic bearing 18a: permanent magnet 18b: permanent magnet 21: casing 22: base 23: first End 23a: Intake port 24: Second end 25: Side portion 26: Valve port 26a: Communication port 27: Base end 28: Exhaust port 28a: Exhaust port 31: Shaft 32: rotor blade unit, 33: rotor cylindrical portion, 33a: outer rotor cylindrical portion, 33b: inner rotor cylindrical portion, 34: rotor blades, 35: motor rotor, 36: motor stator, 37: stator blades, 41: control panel, 41a: button, 41b: lamp, 42: control circuit, 43: IF connector, 44: valve connector, 45: cable, 46a: busbar, 46b: busbar, 47: DC/DC converter, 48a to 48f: switching elements, 49: switching element, 50: diode, 51: first voltage sensor, 52: second voltage sensor, 53: rotation speed detector, 54: controller, 55: regenerative brake resistor, 56: switching element, 61: power failure detector , 62: motor voltage detector, 63: motor PWM signal output section, 64: valve PWM signal output section, A1: axial direction, S1: first internal space, S2: second internal space, Tc: period, Td : predetermined time, Tp: pulse width, Vt: target value, Δt: delay time

Claims (9)

a vacuum pump body having a rotor and a motor for driving the rotor;
a load generator that generates a load for decelerating the motor by supplying the regenerated electric power of the motor;
a control unit that controls so that the regenerative power supplied to the load generation unit is gradually increased,
Vacuum pump. The load generating unit has an electromagnetic valve that supplies air to the interior of the vacuum pump body in an open state,
The control unit controls to gradually increase the regenerative electric power supplied to the solenoid valve to bring the solenoid valve into the open state.
A vacuum pump according to claim 1. The load generation unit has a brake resistance that converts the regenerated electric power into thermal energy,
The control unit controls to gradually increase the regenerative power supplied to the brake resistor.
A vacuum pump according to claim 1. a switching element that supplies the regenerative power to the load generating section in an open state and stops supplying the regenerative power to the load generating section in a closed state;
The control unit outputs a pulse signal that opens and closes the switching element, and modulates the pulse signal to control so that the regenerative power supplied to the load generation unit is gradually increased.
The vacuum pump according to any one of claims 1-3. The control unit gradually increases the supply of the regenerative power supplied to the load generation unit by gradually increasing the duty ratio of the pulse width of the pulse signal.
5. A vacuum pump according to claim 4. Further comprising a voltage detection unit that measures the voltage of the motor in the regenerative drive,
The control unit changes the regenerative power supplied to the load generation unit based on the value detected by the voltage detection unit.
The vacuum pump according to any one of claims 1-5. Further comprising a power detection unit that detects information regarding power supply to the vacuum pump from the outside,
When the control unit detects stoppage of power supply from the outside based on detection by the power detection unit, the control unit controls the regenerative power supplied to the load generation unit to gradually increase.
A vacuum pump according to any one of claims 1 to 6. The control unit gradually increases the regenerative power supplied to the load generation unit after a predetermined delay time when the control unit detects the stoppage of the power supply from the outside based on the detection by the power detection unit. to control,
A vacuum pump according to claim 7. a detection step of detecting discontinuation of power supply to the vacuum pump;
A load generation unit capable of generating a load for decelerating the motor by supplying power from the regenerative power generated by regeneratively driving the motor that drives the rotor of the vacuum pump after the stoppage of the power supply is detected. a power supply step of gradually increasing the power supplied,
How to control a vacuum pump.

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