JP2011055587A - Turbomachinery system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a new method to counter heat for a turbomachinery equipped with a motor. <P>SOLUTION: In a turbomachinery system which includes a turbomachinery T equipped with an impeller 2 and a motor 3 for directly rotating the impeller 2 and a driver D that supplies the motor 3 with power, the driver D includes an inverter 12 which generates a voltage in PWM waveform and a sine wave filter 14 which is interposed between the inverter 12 and the motor 3 to transform the PWM waveform into sine waveform. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a turbomachine system including an impeller and a motor that rotationally drives the impeller.

For example, as a turbo machine, a turbo blower including an impeller and a motor that rotationally drives the impeller as described in Patent Document 1 is known.
A turbomachine having a direct connection between such an impeller and a motor performs work on gas (fluid) by the impeller being directly rotated by driving the motor. Specifically, when the turbo machine is a turbo blower, gas (fluid) is pumped by rotating the impeller.

Such a turbomachine constitutes a turbomachine system together with a drive device for driving the turbomachine, and is driven by electric power supplied from the drive device.
More specifically, the impeller is directly rotated by supplying electric power (voltage and current) to the motor of the turbomachine by the driving device and rotating at a rotational speed corresponding to the fundamental frequency of the supplied electric power.

JP 2000-209815 A

By the way, in the turbo machine in which the motor as described above is directly connected to the impeller, heat is generated in the motor due to power loss, so it is necessary to take measures against heat. In particular, when the impeller is directly rotated at a high speed by the motor, the motor rotor is rotated at a high speed, so that the motor is downsized and the heat radiation area is reduced. Furthermore, since it is difficult to take a means for cooling the rotor rotating at high speed, a countermeasure against heat becomes important.
For this reason, for example, in a turbo machine in which a motor is directly connected to an impeller, a low-viscosity lubricant is used as a lubricant for a bearing that supports a shaft connecting the motor and the impeller, and this lubricant is used as a cooling liquid for the motor. In some cases, a method of cooling the motor by distributing the motor is used.

However, by distributing the lubricant as a coolant, the gas in the motor part in the blower is filled with the lubricating oil. For this reason, when high purity is requested | required with respect to the gas supplied from a turbo blower like a laser oscillation apparatus, for example, the heat countermeasure using the said method is inconvenient.
For this reason, a thermal countermeasure method different from the conventional one is required for a turbo machine including a motor.

  The present invention has been made in view of the above-described problems, and an object thereof is to provide a new heat countermeasure method for a turbo machine in which a motor and an impeller are directly connected.

  Conventionally, in a turbo machine in which a motor and an impeller are directly connected, it is required to rotate the impeller at a high speed of 10,000 rpm or more. For this reason, since it is necessary to rotate the motor directly connected to the impeller at a high speed, an inverter is used as a drive device. In order to make this inverter cheaper, a PWM inverter that outputs a PWM waveform voltage is used to supply power to the motor. However, the PWM inverter includes many harmonic components other than the fundamental frequency in the voltage waveform. And the emitted-heat amount of a motor increases by affecting the harmonic component contained in the supplied voltage. In particular, in the case of a turbo machine in which a motor and an impeller are directly connected, since the impeller is directly rotated at a high speed by the motor, the fundamental frequency for rotating the motor is increased, and the harmonic component becomes a higher frequency component. On the other hand, the power loss of the motor stator and rotor includes iron loss, and it is known that the iron loss increases in proportion to the square of the applied voltage and its frequency. Therefore, the higher harmonic component having a higher frequency increases the loss due to iron loss.

And this invention employ | adopts the following structures as a means for solving the said subject.
A first invention is a turbomachine system including a turbomachine having an impeller and a motor that directly rotates and drives the impeller, and a drive device that supplies electric power to the motor, wherein the drive device includes a PWM (Pulse Width). (Modulation) A configuration is provided that includes an inverter that generates a waveform voltage, and a sine wave filter that is interposed between the inverter and the motor and that makes the PWM waveform sinusoidal.

  According to a second invention, in the first invention, the sine wave filter is a low-pass filter.

  A third invention adopts a configuration in which the motor is driven at a rotational speed of 10,000 rpm or more in the first or second invention.

  According to a fourth invention, in any one of the first to third inventions, a configuration is adopted in which the motor is an induction motor.

  According to a fifth invention, in any one of the first to third inventions, the motor is a permanent magnet motor.

  According to a sixth aspect of the present invention, in any of the first to fifth aspects of the present invention, a configuration is provided in which a bearing that supports a shaft that connects the motor and the impeller is provided, and grease is used as a lubricant for the bearing. .

According to the present invention, the PWM voltage waveform generated by the inverter is made sinusoidal by the sine wave filter, and the harmonic component is removed. That is, harmonic components that lead to an increase in the amount of heat generation are removed from the power component, and the electric power from which these harmonic components have been removed is supplied to the motor. As a result, the amount of heat generated by the motor can be suppressed.
As described above, according to the present invention, it is possible to take a heat countermeasure for the turbomachine by a new method that has not been conventionally performed.

1 is a system configuration diagram illustrating a schematic configuration of a turbo blower system according to a first embodiment of the present invention. It is sectional drawing which shows schematic structure of the turbo blower with which the turbo blower system in 1st Embodiment of this invention is provided. It is a system block diagram which shows schematic structure of the turbo blower system in 2nd Embodiment of this invention.

Hereinafter, an embodiment of a turbomachine system according to the present invention will be described with reference to the drawings. In the following drawings, the scale of each member is appropriately changed in order to make each member a recognizable size.
In the following description, a turbo blower system including a turbo blower (turbo machine) will be described as an example of a turbo machine system.

(First embodiment)
FIG. 1 is a system configuration diagram showing a schematic configuration of a turbo blower system S1 of the present embodiment. As shown in this figure, the turbo blower system S1 of this embodiment includes a turbo blower T and a drive device D.

The turbo blower T includes an impeller and a motor that directly rotates the impeller, and pumps gas (fluid) by driving the motor.
The turbo blower 1 will be described in more detail with reference to FIG. FIG. 2 is a cross-sectional view showing a schematic configuration of the turbo blower T. As shown in this figure, the turbo blower T includes a casing 1, an impeller 2, a motor 3, a shaft 4, a bearing 5, a hermetic connector 6, and a water cooling jacket 7.

The casing 1 forms the outer shape of the turbo blower T and accommodates the gas flow path, the impeller 2, the motor 3, the shaft 4, the bearing 5, and the like inside.
As shown in FIG. 2, an impeller housing space K <b> 1 for housing the impeller 2 and a motor housing space K <b> 2 for housing the motor 3 are provided inside the casing 1. The casing 1 also includes a scroll flow path 1b that gently expands to a suction port 1a for sucking gas and a discharge port for discharging gas. The impeller accommodating space K1 is disposed between the suction port 1a and the scroll flow path 1b and is a part of the gas flow path.

  The impeller 2 is housed and disposed in the impeller housing space K1, and rotates to feed the gas supplied from the suction port 1a to the scroll passage 1b.

The motor 3 rotates the impeller 2 and is accommodated in the motor accommodating space K2. In the present embodiment, an induction motor is used as the motor 3.
The motor 3 includes a motor rotor 3a in which a cage-type conductive material (coil) is incorporated, and a motor stator 3b disposed so as to surround the motor rotor 3a. Then, when electric power is supplied from the driving device D to the motor stator 3b, the motor rotor 3a rotates.
Further, a permanent magnet motor may be used as the motor 3, and the motor rotor 3a may be a motor rotor 3a having a permanent magnet built therein.

The shaft 4 connects the motor 3 and the impeller 2, and transmits the power of the motor 3 to the impeller 2. More specifically, as shown in FIG. 2, the shaft 4 is inserted into the motor rotor 3 a with one end fixed to the impeller 2, and rotates with the rotation of the motor rotor 3 a to transfer the power of the motor 3 to the impeller 2. To communicate.
As a method for connecting the impeller 2 and the shaft 4, for example, a connection method using bolts and nuts, a connection method using screws, a connection method using shrink fitting, a connection method using welding, a connection method using integration, and the like. Conceivable. By being connected by such a method, the impeller 2 rotates integrally with the shaft 4 and the motor rotor 3a. That is, the impeller 2 is directly connected to the motor 3 and is directly driven to rotate by the motor 3.
The connection method using a bolt and a nut is provided with a through hole in the central portion of the impeller along the rotational axis direction, the one end side of the shaft is inserted into the through hole, and the tip end portion of the shaft is projected from the through hole opening, The impeller 2 is fixed to the shaft 4 by fastening a nut to a male screw formed at the tip of the shaft and pressing the tip of the impeller 2 with the nut.
The connection method using a screw is a structure in which a screw is directly cut between the impeller 2 and the shaft 4. Which is the male screw or the female screw is arbitrary.
The connection method by integration is a structure in which the impeller 2 and the shaft 4 are integrally formed without forming a joint.
The impeller 2 and the shaft 4 thus fastened rotate together with the motor roller 3a.

The bearing 5 supports the shaft 4 in an upright state, and an inner ring is fixed to the shaft 4 and an outer ring is fixed to the casing 1.
As shown in FIG. 2, as the bearing 5, an impeller side bearing 5 a that supports the shaft 4 near the impeller 2 and a ground side bearing 5 b that supports the shaft 4 near the ground are provided. The ground-side bearing 5 b is slidable with respect to the casing 1 and is urged upward by a preload spring 8. Thus, the ground side bearing 5b is urged by the preload spring 8, so that the bearing 5 is optimally preloaded and the behavior of the balls inside the bearing 5 (5a, 5b) can be maintained in an appropriate state during rotation. .

The hermetic connector 6 is a connector that enables power supply to the motor 3 while maintaining the state where the impeller accommodating space K1 and the motor accommodating space K2 are completely sealed, and is fixed to the casing 1 while being exposed to the outside. Yes.
Note that the turbo blower T of the present embodiment is mounted on a laser oscillation device and is assumed to pump gas in an environment where inflow of outside air is not permitted. For this reason, the hermetic connector 6 is used. However, when it is not necessary to completely seal the impeller accommodating space K1 and the motor accommodating space K2, a normal connector can be used instead of the hermetic connector 6.

  The water cooling jacket 7 is provided in the casing 1 around the motor 3 and cools the motor with cooling water.

  Returning to FIG. 1, the driving device D supplies electric power to the motor 3 of the turbo blower T, and includes a converter 11, an inverter 12, a control device 13, and a sine wave filter 14. Normally, converter 11, inverter 12 and control device 13 are unitized, and this unitized device is often called an inverter.

The converter 11 once converts a commercial three-phase AC voltage or the like into a DC voltage and outputs it.
The inverter 12 generates a voltage having a PWM waveform from the DC voltage input from the converter 11 under the control of the control device 13 as shown in FIG. The voltage of the PWM waveform is a rectangular wave whose pulse width changes with time, and includes many harmonic components other than the fundamental frequency for rotating the motor.
The control device 13 controls the inverter 12 to change the waveform pattern of the voltage of the PWM waveform generated by the inverter 12 according to the required number of rotations of the motor 3.

The sine wave filter 14 is interposed between the inverter 12 and the motor 3, and makes the voltage of the PWM waveform generated by the inverter 12 a sine wave.
As the sine wave filter 14, a low-pass filter that removes harmonic components can be used. As the sine wave filter 14, a band pass filter or a band elimination filter can be used. However, in consideration of circuit simplification and cost reduction, it is preferable to use a low pass filter.
The sine wave filter 14 is electrically connected to the motor stator 3b of the motor 3 via a hermetic connector, and supplies a sine wave voltage to the motor stator 3b.

According to the turbo blower system S <b> 1 of the present embodiment having such a configuration, the inverter 12 generates a PWM waveform voltage from the DC voltage output from the converter 11 under the control of the control device 13.
Subsequently, the sine wave filter 14 removes the harmonic component from the voltage of the PWM waveform to output a sine wave voltage.
Then, a sinusoidal voltage is supplied to the motor stator 3b via the hermetic connector, whereby the motor rotor 3a is rotated, and further, the impeller 2 is rotationally driven via the shaft 4.

As described above, in the turbo blower system S1 of the present embodiment, the voltage generated by the inverter 12 is made a sine wave by the sine wave filter 14, and the harmonic component is removed.
As described above, in the case of a turbo machine in which a motor and an impeller are directly connected, since the impeller is directly rotated at a high speed by the motor, the fundamental frequency for rotating the motor is increased, and the harmonic component is a higher frequency component. On the other hand, the power loss of the motor stator and rotor includes iron loss, and it is known that the iron loss increases in proportion to the square of the applied voltage and its frequency. Therefore, the higher harmonic component having a higher frequency increases the loss due to iron loss.
Thus, the amount of heat generated by the motor 3 increases due to the influence of the harmonic components included in the supplied voltage. In particular, in the case of a turbo machine in which a motor and an impeller are directly connected, the loss greatly affects. For this reason, the harmonic component is removed from the voltage as in the turbo blower system S1 of the present embodiment, and the voltage from which the harmonic component is removed is supplied to the motor 3, whereby the power due to the harmonic iron loss of the motor 3 is increased. Loss can be greatly reduced, and the amount of heat generated can be suppressed.
As described above, according to the turbo blower system S1 of the present embodiment, it is possible to take a heat countermeasure for the turbo blower T by a new method that has not been conventionally performed.

Further, in the turbo blower system S1 of the present embodiment, an induction motor is used as the motor 3. In the case of an induction motor, a squirrel-cage conductive material (coil) is built into the motor rotor, and the rotor part is accompanied by an electrical loss. However, according to this embodiment, the loss other than the fundamental frequency component necessary for the rotation is suppressed. Can do.
As the motor, a permanent magnet motor may be used. In the permanent magnet motor, there is no power loss in the motor rotor 3a because there is no coil through which current flows in the motor rotor 3a. For this reason, it becomes possible to further suppress the calorific value of the motor itself.
In particular, in the turbo blower system of this embodiment, the impeller is driven at a high speed rotation of 10,000 rpm or more. When driving at such a rotational speed, harmonic components included in the voltage of the PWM waveform greatly affect power loss. Therefore, when driving at this rotational speed or higher, the countermeasure of this embodiment is very effective.

Further, by taking a new heat countermeasure that has not been conventionally performed as described above, it may be unnecessary to cool the motor by distributing the lubricant of the bearing as described above as a coolant. In such a case, it is preferable to use a highly viscous grease as the bearing lubricant.
Accordingly, it is possible to suppress the lubricant from entering the gas flow path pumped by the turbo blower T, and to suppress the mixture of the lubricant with the gas.

(Second Embodiment)
Next, a second embodiment of the present invention will be described. In the description of the second embodiment, the description of the same parts as in the first embodiment will be omitted or simplified.

  FIG. 3 is a system configuration diagram showing a schematic configuration of the turbo blower system S2 of the present embodiment. As shown in this figure, the turbo blower system S2 of the present embodiment includes a cooling gas supply device 20 and an exhaust pump 21 in addition to the turbo blower system S1 of the first embodiment.

Further, in the turbo blower system S2 of the present embodiment, a through hole 1c for connecting the motor housing space K2, the cooling gas supply device 20, and the exhaust pump 21 is formed in the casing 1 of the turbo blower T.
In the turbo blower system S2 of the present embodiment, as the through hole 1c, an upper through hole 1ca communicating with the upper part of the motor housing space K2 and a lower through hole 1cb communicating with the lower part of the motor housing space K2 are provided. Yes.

The cooling gas supply device 20 supplies cooling gas into the motor housing space K2 through the upper through hole 1ca.
The exhaust pump 30 exhausts the cooling gas introduced into the motor housing space K2 through the lower through hole 1ca.

According to the turbo blower system S2 of the present embodiment having such a configuration, a cooling gas flow from the upper side to the lower side is formed in the motor housing space K2, and the motor 3 is arranged in such a cooling gas flow. It becomes.
For this reason, according to the turbo blower system S2 of the present embodiment, the motor 3 is cooled by the cooling gas, and the influence of the amount of heat generated from the motor 3 can be further reduced.

  As mentioned above, although preferred embodiment of this invention was described referring drawings, this invention is not limited to the said embodiment. Various shapes, combinations, and the like of the constituent members shown in the above-described embodiments are examples, and various modifications can be made based on design requirements and the like without departing from the gist of the present invention.

For example, in the above embodiment, the configuration in which the turbo machine of the present invention is a turbo blower has been described.
However, the present invention is not limited to this, and for example, a turbo pump or the like can be used as the turbo machine of the present invention.

Moreover, in the said 2nd Embodiment, the structure provided with the cooling gas supply apparatus 20 and the exhaust pump 30 was demonstrated as a new structure.
However, when the turbo blower system S2 of the second embodiment is mounted on a laser oscillation device, the gas pumped by the turbo blower T is cooled inside the laser transmission device. For this reason, you may supply this cooled gas to the inside of the motor accommodation space K2 via the upper through-hole 1ca. Further, since the laser oscillation device includes an exhaust pump for exhausting the gas, the exhaust pump can also be used as the exhaust pump 30 in the second embodiment.

  S1, S2: Turbo blower system (turbo machine system), T: Turbo blower (turbo machine), D: Drive unit, 2 ... Impeller, 3 ... Motor, 4 ... Shaft, 5 ... Bearing, 12 ... ... Inverter, 14 ... Sine wave filter

Claims (6)

A turbomachine system comprising an impeller and a turbomachine having a motor that directly rotates and drives the impeller, and a drive device that supplies electric power to the motor,
The driving device includes:
An inverter that generates a PWM (Pulse Width Modulation) waveform voltage;
A sine wave filter interposed between the inverter and the motor and making the PWM waveform sinusoidal;
A turbomachine system comprising:   The turbomachine system according to claim 1, wherein the sine wave filter is a low-pass filter.   The turbo machine system according to claim 1, wherein the motor is driven at a rotational speed of 10,000 rpm or more.   The turbo machine system according to claim 1, wherein the motor is an induction motor.   The turbo machine system according to claim 1, wherein the motor is a permanent magnet motor.   The turbomachine system according to claim 1, further comprising a bearing that supports a shaft that connects the motor and the impeller, wherein grease is used as a lubricant for the bearing.

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