JP2009136060A - Flywheel-type uninterruptible power supply device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To feed power to an electric motion resistance reduction means for reducing resistance against the rotational motion of a flywheel for a long period of time until the interruption of power supply is recovered. <P>SOLUTION: When a current value of power generated by a cage-type induction motor 10 which is rotated during power interruption by inertia energy accumulated in the flywheel 9 is raised to a rated current value of the cage-type induction motor 10 due to the decrease of the number of revolutions resulting from a magnetic force between a stator and a rotor, and the lowering of a voltage value of generated power accompanied by the decrease of the number of revolutions, a first switch SW1 in a closed state is released by a controller 16, and the feed of the power generated by the cage-type induction motor 10 to a load 8 is stopped. By this arrangement, power consumption is reduced while setting destinations of power supply as only a magnetic bearing 17 and drive units 17a, 19a of a vacuum pump 19, and the power generated by the cage-type induction motor 10 is lowered, thus preventing the current value of the generated power from being raised to a value not smaller than the rated current value. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an uninterruptible power supply apparatus using a flywheel and an induction motor, and in particular, a fly having a configuration for reducing energy loss by reducing resistance to rotational movement of a flywheel by means of an electric movement resistance reducing means. The present invention relates to a wheel type uninterruptible power supply.

  In a system that supplies power from an emergency generator in place of a power supply in the event of a power failure, a time lag from the occurrence of the power failure to the startup of the emergency generator is inevitable. Therefore, an uninterruptible power supply (UPS) that supports power supply to the load is indispensable during this time lag.

  One such uninterruptible power supply is a flywheel uninterruptible power supply. The flywheel type uninterruptible power supply device rotates the flywheel during standby when the power supply is normal, and rotates the induction motor with the flywheel that continues to rotate even after the power failure, so that the induction motor is in power failure. It is operated as a generator. Such a flywheel type uninterruptible power supply is attracting attention because it has advantages such as not outputting harmonics.

  By the way, a flywheel type uninterruptible power supply is a device that causes an induction motor to generate electric power using a force by which the flywheel rotates with inertia, that is, rotational energy accumulated in the flywheel. Therefore, in the flywheel uninterruptible power supply, it is important to suppress the resistance to the rotational movement of the flywheel as much as possible.

Therefore, conventionally, proposals have been made to reduce the frictional force between the rotary shaft of the flywheel and the bearing by applying buoyancy to the flywheel by electromagnetic force (for example, Patent Document 1), and arranging the flywheel in a vacuum space. And the proposal (for example, patent document 2) which reduces the windage loss which acts on a flywheel by the surrounding atmosphere of a flywheel is performed.
JP 2003-143774 A JP-A-7-194028

  In order to execute the countermeasure for suppressing the resistance to the rotational movement of the flywheel as described above, an electric element such as an electromagnetic coil or a vacuum pump is required. When the power supply to this electric element is cut off, the resistance suppression force that had been acting on the flywheel until then stops working instantaneously, and that much impact force is applied to the flywheel rotating shaft bearing. become. This impact force can sometimes contribute to damage to the bearing.

  Therefore, when taking measures to suppress the resistance to the rotational movement of the flywheel, it is important to stably supply electric power to the electric elements necessary for that purpose. In particular, when a power failure occurs, the uninterruptible power supply itself needs to supply power to these electric elements.

  In this case, even if the emergency generator starts up for a moment after the occurrence of a power failure, the power from the emergency generator is supplied exclusively to the load. Therefore, it cannot be expected that the uninterruptible power supply device having the above-described electric element is supplied with power from the emergency generator. In addition, even if power can be supplied from the emergency generator, if the power is interrupted for a moment from the occurrence of a power failure until the emergency generator starts up, There is a risk that a large impact force is applied to the bearing, resulting in damage to the bearing.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a power failure in a flywheel uninterruptible power supply that reduces resistance to rotational movement of a flywheel by means of an electric movement resistance reducing means. In some cases, there is provided a flywheel uninterruptible power supply that enables electric power to be supplied to the electric motion resistance reducing means for a longer period until the power failure is restored.

  In order to achieve the above object, the flywheel uninterruptible power supply apparatus according to the first aspect of the present invention uses power generated by an induction motor rotated during a power failure by a flywheel rotated during standby to supply power during a power failure. A flywheel that supplies the load instead of the electric wheel and maintains the operation at the time of a power failure of the electric movement resistance reducing means for reducing the resistance to the rotational movement of the flywheel by supplying electric power generated by the induction motor. In the type uninterruptible power supply, when the current value of the electric power generated by the induction motor increases until reaching the rated current value of the induction motor, the supply of the electric power generated by the induction motor to the motion resistance reducing means is maintained. A supply interruption means for electrically interrupting a supply path to the load of power generated by the induction motor. It is characterized in.

  According to the flywheel uninterruptible power supply device of the present invention described in claim 1, during a power failure, while the supply path for the load of power generated by the induction motor is electrically connected, the load is operated. The induction motor will continue to generate electricity at the rated output. At this time, the rotational speed of the flywheel and the induction motor decreases with time, and accordingly, if the excitation voltage to the induction motor is constant, the excitation current gradually increases and the rotation speed further decreases. If the excitation voltage to the induction motor decreases, the effective current increases. Therefore, the current of the power induction motor generates power during a power failure gradually increases, eventually reaches a rated current value of the induction motor.

  Then, the supply path for the load of the power generated by the induction motor is electrically interrupted by the supply cutoff means, and consumption by the load of the power generated by the induction motor is eliminated. descend. Thereby, even if the voltage of the electric power generated by the induction motor decreases due to the decrease in the rotational speed of the flywheel and the induction motor, the current value of the electric power does not exceed the rated current value of the induction motor.

  Therefore, it is possible to prevent a current exceeding the rated current value from flowing through the induction motor to cause burning or the like, or to cause a trip in the inverter provided on the power supply path to the load. Therefore, the power supply to the movement resistance reducing means is not cut off due to the occurrence of these events.

  For this reason, until the rotation of the flywheel stops and the induction motor becomes unable to generate electric power, the induction motor can generate electric power, and the electric power can be continuously supplied to the movement resistance reducing means. As a result, the movement resistance mitigation means is operated for a longer period during a power outage, and the arrival of the point at which the resistance suppression force that had previously acted on the flywheel no longer acts instantaneously due to the suspension of the movement resistance mitigation means. Can be delayed. Therefore, it is possible to avoid as much as possible that the flywheel collides against the bearing of the rotating shaft due to the motion resistance that acts on the flywheel, and a large impact force is applied to the bearing from the flywheel to cause damage to the bearing.

  Moreover, the flywheel type uninterruptible power supply device of the present invention described in claim 2 is the flywheel type uninterruptible power supply device of the present invention described in claim 1, wherein the supply interruption means generates power from the induction motor. An open / close switch interposed on a dedicated supply path for a load of electric power, a current sensor for detecting a current value of electric power generated by the induction motor, and a detected current value by the current sensor is a rated current of the induction motor And a controller that opens the open / close switch that is closed when the value is increased to a value.

  According to the flywheel uninterruptible power supply of the present invention described in claim 2, in the flywheel uninterruptible power supply of the present invention described in claim 1, the current value detected by the current sensor is the rated current of the induction motor. When the value increases, the open / close switch provided on the dedicated supply path for the load of power generated by the induction motor is switched from the closed state to the open state by the controller, and the load for the power generated by the induction motor The supply path is electrically interrupted.

  Therefore, it is possible to reliably prevent an increase in the generated current of the induction motor that exceeds the rated current value of the generated power of the induction motor, which causes the burnout of the induction motor and the trip of the inverter, and means for reducing the movement resistance during a power failure The power supply to can be continued as much as possible, and the power generation of the induction motor by the rotation of the flywheel can be continued for a long time.

  Further, the flywheel uninterruptible power supply apparatus according to the present invention described in claim 3 is the flywheel uninterruptible power supply apparatus according to the present invention described in claim 1, wherein the supply interruption means generates power from the induction motor. An open / close switch provided on a dedicated supply path for a load of electric power, a rotational speed sensor for detecting the rotational speed of the induction motor, and a current value of power generated by the induction motor is a rated current of the induction motor. And a controller that opens the open / close switch that is closed when the rotational speed detected by the rotational speed sensor per unit time has decreased to a predetermined rotational speed that reaches a value.

  According to the flywheel uninterruptible power supply of the present invention described in claim 3, in the flywheel uninterruptible power supply of the present invention described in claim 1, the rotational speed detected by the rotational speed sensor per unit time is When the current value of the electric power generated by the induction motor decreases to a predetermined rotational speed that reaches the rated current value of the induction motor, an open / close switch provided on a dedicated supply path for the load of the electric power generated by the induction motor is The controller switches from the closed state to the open state, and the supply path for the load of power generated by the induction motor is electrically interrupted.

  Therefore, it is possible to reliably prevent an increase in the generated current of the induction motor that exceeds the rated current value of the generated power of the induction motor, which causes the burnout of the induction motor and the trip of the inverter, and means for reducing the movement resistance during a power failure The power supply to can be continued as much as possible, and the power generation of the induction motor by the rotation of the flywheel can be continued for a long time.

  Moreover, the flywheel type uninterruptible power supply device of the present invention described in claim 4 is the flywheel type uninterruptible power supply device of the present invention described in claim 1, 2, or 3, wherein the movement resistance reducing means is the It has the magnetic bearing of the rotating shaft of a flywheel.

  According to the flywheel uninterruptible power supply device of the present invention described in claim 4, in the flywheel uninterruptible power supply device of the present invention described in claim 1, 2 or 3, buoyancy is applied to the flywheel by electromagnetic force. The electric power necessary for the action is generated by the induction motor and supplied to the magnetic bearing until the rotation of the flywheel stops.

  For this reason, the magnetic bearing can be operated for a longer period during a power outage, and the arrival of the point at which the buoyancy that had been acting on the flywheel until then due to the suspension of the operation of the magnetic bearing is stopped instantaneously can be delayed as much as possible. Therefore, it is possible to avoid as much as possible that the flywheel collides against the bearing of the rotating shaft due to the motion resistance that acts on the flywheel, and a large impact force is applied to the bearing from the flywheel to cause damage to the bearing.

  Further, the flywheel uninterruptible power supply of the present invention described in claim 5 is the flywheel uninterruptible power supply of the present invention described in claim 1, 2, 3 or 4, wherein the movement resistance reducing means is The flywheel includes a chamber in which the flywheel is accommodated in an internal space, and a decompression device that decompresses the internal space.

  According to the flywheel uninterruptible power supply device of the present invention described in claim 5, the flywheel is accommodated in the flywheel uninterruptible power supply device of the present invention described in claim 1, 2, 3 or 4. Electric power necessary to reduce the internal space of the chamber, reduce the gravity acting on the flywheel, and reduce windage damage due to the atmosphere surrounding the flywheel is generated by the induction motor until the flywheel stops rotating. It will be supplied to the decompression device.

  For this reason, the decompression device is operated for a longer period during a power outage, and the arrival of the moment when the gravity reduction function and windage loss reduction function that had been working on the flywheel until the time when the decompression device stopped operating stops instantaneously as much as possible Can be made. Therefore, it is possible to avoid as much as possible that the flywheel collides against the bearing of the rotating shaft due to the motion resistance that acts on the flywheel, and a large impact force is applied to the bearing from the flywheel to cause damage to the bearing.

  According to the flywheel uninterruptible power supply apparatus of the present invention, the resistance suppression force that has been acting on the flywheel until then by operating the movement resistance reduction means during a power outage for a longer period of time and stopping the movement resistance reduction means. It is possible to delay the arrival of the point at which the operation stops instantaneously as much as possible. Therefore, it is possible to avoid as much as possible that the flywheel collides against the bearing of the rotating shaft due to the motion resistance that acts on the flywheel, and a large impact force is applied to the bearing from the flywheel to cause damage to the bearing.

  Embodiments of a flywheel uninterruptible power supply according to the present invention will be described below with reference to the drawings.

  FIG. 1 illustrates an uninterruptible power generator 1 according to a first embodiment of the present invention. An emergency generator (not shown) starts up on a DC bus 4 of a power supply system (path) 3 at a normal time by a power supply 2 from the occurrence of a power failure. It is explanatory drawing shown as a structure connected as what supplies electric power until. In FIG. 1, reference numeral 5 is a power supply system (path) at the time of a power failure.

  Although the uninterruptible power supply 1 will be described later in detail, a squirrel-cage induction motor 10 is employed. When the power source 2 is in a standby state where no power failure occurs, the flywheel 9 and the squirrel-cage induction motor 10 are in an idling state by de-energizing the squirrel-cage induction motor 10 connected to the flywheel 9 in a rotating state due to inertia. And

  Since the squirrel-cage induction motor 10 is not excited in the idling state, it is necessary to pass an excitation current in a short time to the squirrel-cage induction motor 10 that rotates at a high speed in order to perform a power regeneration operation. Therefore, the uninterruptible power supply 1 excites the exciting coil of the squirrel-cage induction motor 10 within a short time after the controller 16 detects a power failure and starts power generation. The uninterruptible power supply 1 can also be used for high-speed excitation for powering.

  In FIG. 1, a normal power supply system (path) 3 converts, for example, a three-phase AC voltage from a power source 2 into a DC voltage by a rectifier 6 and supplies it to a load inverter 7 through a DC bus 4. For example, the load inverter 7 generates an AC voltage having a frequency of 50 Hz and supplies the AC voltage to the load 8 via the first switch SW1.

  In the power supply system (path) 5 at the time of a power failure, a squirrel-cage induction motor 10 is connected to the rotating shaft 9a of the flywheel 9 and used as a flywheel generator. The electric power generated by this generator is used as a flywheel inverter 11. Is converted to a DC voltage and supplied to the DC bus 4.

  The squirrel-cage induction motor 10 is an electric motor using a wound rotor and a stator, and becomes a motor or a generator. When operating as a motor, the flywheel 9 is accelerated to a predetermined speed. When operating as a generator, power is generated according to the rotational force based on the inertial energy of the flywheel 9.

  The flywheel 9 is a disk having inertia and mass. Upper and lower ends of the rotary shaft 9a of the flywheel 9 is bearing respectively by the magnetic bearing 17 arranged above and below the flywheel 9.

  Each magnetic bearing 17 has a plurality of radial centering electromagnets (not shown) disposed at equal intervals in the circumferential direction of the rotary shaft 9a so as to face the peripheral surface of the rotary shaft 9a. Further, at least one of the upper and lower magnetic bearings 17 further includes a thrust electromagnet (not shown) arranged in a thrust direction so as to be opposed to a disk-shaped thrust disk integrally formed with the rotary shaft 9a. . The energization amount to each electromagnet is adjusted by the magnetic bearing driving device 17a. This adjustment rotary shaft 9a is floated in the thrust direction by the electromagnetic force from the magnetic bearing 17, and are non-contact bearings a radial direction.

  Further, the flywheel 9, its rotating shaft 9 a, the squirrel-cage induction motor 10, and the upper and lower magnetic bearings 17 are accommodated in an internal space of a sealed chamber 18. A vacuum pump 19 (decompression device) is connected to the chamber 18, and the internal space of the chamber 18 is decompressed and evacuated by operating the vacuum pump 19 by a vacuum pump drive device 19a. By this pressure reduction and evacuation, the gravity acting on the flywheel 9, its rotating shaft 9a, and the cage induction motor 10 is reduced. The rotational speed of the flywheel 9 is measured as a frequency [Hz] (the rotational speed per unit time) by a rotational speed meter 12 (rotational speed sensor).

  An ammeter 13 is provided between the squirrel-cage induction motor 10 and the flywheel inverter 11, and measures an excitation current value that flows due to an excitation voltage generated by the flywheel inverter 11.

  The flywheel inverter 11 converts the AC voltage from the squirrel-cage induction motor 10 operating as a generator based on the rotational force of the flywheel 9 into a DC voltage and supplies the DC voltage to the DC bus 4. At this time, the DC voltage value is measured by the DC voltmeter 14. The flywheel inverter 11 supplies an excitation voltage and an excitation current to the cage induction motor 10.

  The capacitor 15 has a minimum power energy for operating the flywheel inverter 11 when the power is cut off due to a power failure or the like, and a period from when the power failure occurs until power generation is started by the squirrel-cage induction motor 10. The power energy required by the load 8 is accumulated.

  That is, the power supply to the load 8 when a power failure occurs can use the generated energy if power generation is started by the squirrel-cage induction motor 10, but the power from the capacitor 15 is used until power generation. If the load 8 is of a property that allows it to be placed in an instantaneous power failure state, the load inverter 7 is turned on for a short period from the time of the power failure to the time when the cage induction motor 10 is excited to start power generation. It is possible to keep the capacitance of the capacitor 15 to a minimum by stopping and preventing the power of the capacitor 15 from being supplied to the load 8. Note that the DC power converted by the flywheel inverter 11 is not supplied to the capacitor 15.

  In the uninterruptible power supply 1 having such a configuration, the squirrel-cage induction motor 10 in the power supply path 5 normally operates as a motor and accelerates the flywheel 9. When the rotational speed of the flywheel 9 is sufficiently increased, the excitation of the squirrel-cage induction motor 10 is stopped and the flywheel 9 is left idle. Since the flywheel 9 and the squirrel-cage induction motor 10 are connected, the rotor of the squirrel-cage induction motor 10 continues to rotate.

  As described above, the flywheel 9 accumulates inertial energy and idles. In this state, for example, when a power failure occurs, the flywheel inverter 11 operates the squirrel-cage induction motor 10 as a generator based on the rotational force of the flywheel 9. The AC energy generated by the squirrel-cage induction motor 10 is supplied to the flywheel inverter 11. The DC voltage converted from AC to DC by the flywheel inverter 11 is supplied to the DC bus 4 while being measured by the DC voltmeter 14. The load inverter 7 converts the generated power supplied to the DC bus 4 into 50 Hz AC as described above, and supplies it to the load 8 via the first switch SW1.

  The magnetic branch drive device 17a and the vacuum pump drive device 19a are supplied with power branched from the normal power supply system (path) 3 after being converted from alternating current to direct current by the transformer 21. The transformer 21 is branch-connected to the normal power supply system (path) 3 between the load inverter 7 and the first switch SW1. A second switch SW2 is interposed between the branch point and the transformer 21. Further, an ammeter 22 is provided between the power source 2 and the rectifier 6 to measure the current value of the power supplied from the power source 2.

  The first and second switches SW1 and SW2 are closed in principle regardless of the presence or absence of a power failure. The opening and closing of the first and second switches SW1 and SW2 are controlled by the controller 16 based on the measurement results of the revolution meter 12 or the ammeters 13 and 22 during a power failure.

  In this way, the uninterruptible power supply 1 uses the power from the load inverter 7 based on the power from the rectifier 6 in the normal power supply path 3 for the load 8 and the power supply path 5 in the event of a power failure. The electric power generated by the squirrel-cage induction motor 10 can be supplied via the first switch SW1. Therefore, the portion on the load 8 side from the branch point of the power supply path to the magnetic bearing drive device 17a and the vacuum pump drive device 19a among the power supply route 3 at the normal time and the power supply route 5 at the time of power failure is dedicated to the load 8. This is the power supply path part.

  In particular, the uninterruptible power supply 1 operates based on the following principle. First, at normal time, the squirrel-cage induction motor 10 connected to the flywheel 9 is brought into a non-excited state when the flywheel 9 reaches a predetermined speed, and the flywheel 9 is rotated as it is at a high speed. This state, that is, a state in which the cage induction motor 10 is de-energized and the flywheel 9 is idling at a predetermined high speed is referred to as an idle state.

  In this idle state, inertial kinetic energy is accumulated in the flywheel 9. From this state, the squirrel-cage induction motor 10 is excited by the control of the flywheel inverter 11 and the rotational speed (slip) control is performed to generate power by kinetic energy.

  At this time, the flywheel 9 and the induction motor 10 are supported by the magnetic bearing 17 in a floating and non-contact state. Thereby, reduction of the rotation loss of the flywheel 9 by the friction accompanying the contact with the rotating shaft 9a of the flywheel 9 and the magnetic bearing 17 is achieved.

  Further, the flywheel 9 and the induction motor 10 are accommodated in a chamber 18 that is reduced in pressure or vacuum by a vacuum pump 19. Thereby, reduction of the gravity which acts on the flywheel 9, its rotating shaft 9a, and the cage induction motor 10 is achieved. In addition, by reducing the pressure in the chamber 18 by the vacuum pump 19 or in a vacuum state, the rotational loss of the flywheel 9 or the induction motor 10 due to the wind loss that the flywheel 9 receives from the surrounding atmosphere is reduced. .

  Therefore, the supply of electric power to the magnetic bearing driving device 17a and the vacuum pump driving device 19a is very important for maintaining the operation of the magnetic bearing 17 and the vacuum pump 19 described above. When these operations are not maintained, that is, when the supply of power is cut off, the buoyancy acting on the flywheel 9 does not act abruptly, and the gravity mitigating action does not act abruptly. Then, the rotating shaft 9a of the flywheel 9 collides with the lower magnetic bearing 17 (in some cases, also on the upper magnetic bearing 17), and a large impact force is applied to the magnetic bearing 17 to cause damage. Since the magnetic bearing 17 is a very expensive part, the damage is not limited to the operation loss as the uninterruptible power supply 1, and causes a large loss economically.

  The uninterruptible power supply device 1 of the present embodiment can maintain the power supply to the magnetic bearing driving device 17a and the vacuum pump driving device 19a for the longest possible time, and to protect the magnetic bearing 17 from damage as much as possible. It is what you want to do.

  Here, the characteristic regarding the electric power generation of the cage induction motor 10 will be described. FIG. 3 is a graph showing the relationship between the number of rotations and the voltage of the generated power of the squirrel-cage induction motor 10 that is in the power generation state by exciting the excitation coil. FIG. 4 is a graph showing the relationship between the rotation speed and the current of the generated power of the squirrel-cage induction motor 10 that is in the power generation state by exciting the excitation coil.

  In order for the uninterruptible power supply 1 of the present embodiment to supply power during a power failure with a rated output corresponding to the power consumption of the load 8, the rotational speed of the squirrel-cage induction motor 10 is set to a power generation compensation lower limit rotational speed (hereinafter, It is abbreviated as “lower limit rotational speed.”) It must be f1 or more. The reason is that when the rotation speed of the squirrel-cage induction motor 10 is lower than the lower limit rotation speed f1, the voltage of the generated power is reduced in proportion to the rotation speed as shown in FIG.

  When the voltage of the generated electric power of the squirrel-cage induction motor 10 decreases as shown in FIG. 3 in proportion to the rotation speed of the squirrel-cage induction motor 10 that is lower than the lower limit rotation speed f1, the load 8 corresponding to the rated output is reduced. since it is followed by the power consumption, as shown in FIG. 4, the electric power generated by electric current, exceeds the rated current of the squirrel-cage induction motor 10. If a current exceeding the rated current value flows through the exciting coil of the squirrel-cage induction motor 10 (becomes an overcurrent state), it may cause burning of the exciting coil, which is not preferable.

  Therefore, in order to cause the squirrel-cage induction motor 10 to generate electric power corresponding to the rated output of the uninterruptible power supply 1 according to the power consumption of the load 8 while keeping the current flowing in the exciting coil below the rated current value, The rotational speed of the mold induction motor 10 needs to be equal to or higher than the lower limit rotational speed f1.

  However, when a power failure occurs in the power source 2 and the squirrel-cage induction motor 10 shifts from the idling state to the excited state and starts power generation, the rotation speed of the squirrel-cage induction motor 10 is increased by the magnetic force between the stator and the rotor described above. It gradually decreases from the rated rotational speed f0 during standby (when idling) and eventually falls below the lower limit rotational speed f1 as shown in FIG.

  Therefore, in the uninterruptible power supply 1 of the present embodiment, the rotation speed of the cage induction motor 10 is lower than the lower limit rotation speed f1, and the current flowing in the exciting coil is as shown in FIG. The controller 16 shown in FIG. 1 controls the power supply to the load 8 so as not to exceed the rated current value.

  In addition to supplying power to the load 8, the controller 16 of the present embodiment also controls excitation of the squirrel-cage induction motor 10 by the flywheel inverter 11 and electrical connection / disconnection of the capacitor 15 to the flywheel inverter 11. . The controller 16 can be configured by a microcomputer that performs processing by executing a control program, various drivers including a V / f conversion circuit (voltage-frequency conversion circuit), and the like.

  FIG. 2 is a flowchart showing a procedure of processing performed by the controller 16 of the uninterruptible power supply 1 by executing a control program. With reference to this FIG. 2, the process regarding especially the electric power supply with respect to the load 8 at the time of the power failure which the controller 16 of this embodiment performs is demonstrated. In the initial state of the process described below, the exciting coil of the squirrel-cage induction motor 10 is excited for power regeneration by the flywheel inverter 11, and the first and second switches SW1 and SW2 are both set. It shall be closed.

  First, the controller 16 determines whether or not the current flowing through the exciting coil of the squirrel-cage induction motor 10 is equal to or less than the rated current value (step S1). This determination is based on the value of the exciting current flowing in the exciting coil by the exciting voltage generated by the flywheel inverter 11 measured by an ammeter 13 provided between the squirrel-cage induction motor 10 and the flywheel inverter 11. Can be done. Or it can also carry out based on the rotation speed of the flywheel 9 thru | or the squirrel-cage induction motor 10 measured as frequency [Hz] (rotation speed per unit time) with the tachometer 12 (rotation speed sensor).

  When the excitation current value measured by the ammeter 13 is used as a basis for determination, it is directly determined whether the excitation current value is equal to or less than the rated current value of the squirrel-cage induction motor 10. On the other hand, when the value of the rotation speed of the squirrel-cage induction motor 10 measured by the tachometer 12 is used as a basis for determination, the squirrel-cage induction motor depends on whether or not the rotation speed is equal to or higher than the lower limit rotation speed f1 described above. It is indirectly determined whether or not the current value flowing through the ten exciting coils is equal to or less than the rated current value.

  If it is determined in step S1 that the current flowing through the exciting coil of the squirrel-cage induction motor 10 is equal to or less than the rated current value, the controller 16 determines whether or not the power failure has been restored (step S3). This determination is measured by the ammeter 22 provided between the power supply 2 and the rectifier 6 can be performed based on the current value of power supplied from the power supply 2. That is, when the measured current value by the ammeter 22 is zero, it can be determined that the power failure has not been recovered, and when the measured current value is the rated current value of the power source 2, it is determined that the power failure has been recovered. can do.

  If it is not determined in step S3 that the power failure has been recovered, the process returns to step S1. If it is determined that the power failure has been restored, the process is terminated. After completion of the processing, the excitation for power regeneration of the exciting coil of the cage induction motor 10 is terminated, and the power generation by the cage induction motor 10 is terminated.

  On the other hand, if it is not determined in step S1 that the current flowing through the exciting coil of the squirrel-cage induction motor 10 is less than the rated current value, the controller 16 opens the first switch SW1 in the closed state (step S5). . By opening the first switch SW1, the supply of the power generated by the squirrel-cage induction motor 10 to the load 8 is stopped.

  After opening the first switch SW1, the controller 16 determines whether the rotation of the squirrel-cage induction motor 10 is stopped (step S7). This determination can be made based on whether or not the number of revolutions of the flywheel 9 to the squirrel-cage induction motor 10 measured by the revolution meter 12 (a revolution number sensor) has become zero.

  In step S7, when it is not determined that the rotation of the squirrel-cage induction motor 10 is stopped, the controller 16 determines whether or not the power failure has been recovered, similarly to step S3 (step S9). If it is not determined that the power failure has been restored, the process returns to step S7. If it is determined that the power failure has been restored, the first switch SW1 is closed (step S11), and the process is terminated. After completion of the processing, the excitation for power regeneration of the exciting coil of the cage induction motor 10 is terminated, and the power generation by the cage induction motor 10 is terminated.

  On the other hand, if it is determined in step S7 that the rotation of the cage induction motor 10 is stopped, the second switch SW2 is opened (step S13). By opening the second switch SW2, the supply of the electric power generated by the cage induction motor 10 to the magnetic bearing driving device 17a and the vacuum pump driving device 19a is stopped.

  After opening the second switch SW2, the controller 16 determines whether or not the power failure has been recovered, similarly to step S3 and step S9 (step S15). If it is not determined that the power failure has been restored, step S15 is repeated. If it is determined that the power failure has been restored, the first and second switches SW1 and SW2 are both closed (step S17), and the process ends. After completion of the processing, the excitation for power regeneration of the exciting coil of the cage induction motor 10 is terminated, and the power generation by the cage induction motor 10 is terminated.

  By the process of the controller 16 described above, the electric power generated by the cage induction motor 10 changes as shown by the solid line in the graph of FIG. That is, when a power failure occurs in the power supply 2, the squirrel-cage induction motor 10 rotating at the rated rotational speed f0 starts power generation with a rated output (for example, 100 kW) that matches the power consumption of the load 8. Then, the rotational speed of the squirrel-cage induction motor 10 that gradually decreases from the rated rotational speed f0 due to the magnetic force between the stator and the rotor eventually decreases to the lower limit rotational speed f1, as indicated by the broken line in FIG.

  At this time, as shown in the graph of FIG. 6 showing the relationship between the rotation speed of the squirrel-cage induction motor 10 in the power generation state and the current of the generated power, the current value of the power generated by the squirrel-cage induction motor 10 is The rated current value of the type induction motor 10 increases. Here, under the control of the controller 16, the closed first switch SW <b> 1 is opened, and the supply of the electric power generated by the squirrel-cage induction motor 10 to the load 8 is stopped.

  When the first switch SW1 is opened, the power generated by the squirrel-cage induction motor 10 is continuously supplied through the second switch SW2 and the transformer 21 as shown by the solid line in FIG. The power is reduced to power (for example, 1 kW) corresponding to the power consumption in the device 17a and the vacuum pump drive device 19a. As a result, as shown in FIG. 6, the current value of the electric power generated by the cage induction motor 10 that has increased to the rated current value of the cage induction motor 10 decreases to a current value that is much lower than the rated current value.

  Then, after the first switch SW1 is opened, the electric power generated by the squirrel-cage induction motor 10 passes through the second switch SW2 and the transformer 21 until the rotation of the squirrel-cage induction motor 10 stops and the electric power cannot be generated. Via the magnetic bearing driving device 17a and the vacuum pump driving device 19a. In the meantime, the rotational speed of the squirrel-cage induction motor 10 further decreases from the lower limit rotational speed f1 due to the magnetic force between the stator and the rotor, as shown by the broken line in FIG.

  However, the power consumption by the magnetic bearing driving device 17a and the vacuum pump driving device 19a is much smaller than the power consumption by the load 8, and the generated power (for example, 1 kW) of the cage induction motor 10 corresponding thereto is It is much smaller than the rated output (for example, 100 kW) in accordance with the power consumption of the load 8 before one switch SW1 is opened. Therefore, even if the rotation speed of the cage induction motor 10 further decreases and the voltage value of the generated power by the cage induction motor 10 decreases, the current value of the generated power by the cage induction motor 10 again reaches the rated current value. It will not rise.

  When the rotation of the squirrel-cage induction motor 10 is stopped and power cannot be generated, the second switch SW2 in the closed state is opened under the control of the controller 16 to drive the magnetic bearing driving device 17a or the vacuum pump. The power supply to the device 19a is stopped.

  Therefore, it is possible to reliably prevent an increase in current that exceeds the rated current value of the generated power of the squirrel-cage induction motor 10, which becomes a cause of burning of the exciting coil of the squirrel-cage induction motor 10 and tripping of the flywheel inverter 11. Can do. Thereby, the electric power supply from the cage induction motor 10 to the magnetic bearing drive device 17a and the vacuum pump drive device 19a during the power failure can be continued until the last moment when the rotation of the cage induction motor 10 stops.

  Therefore, the magnetic bearing 17 is driven by the magnetic bearing driving device 17a until the last moment when the rotation of the squirrel-cage induction motor 10 stops, and the flywheel 9 and the induction motor 10 remain in a floating and non-contact state. Will be kept.

  Further, the vacuum pump 19 is driven by the vacuum pump driving device 19a until the last stage when the rotation of the squirrel-cage induction motor 10 stops, and the inside of the chamber 18 is maintained in a reduced pressure or vacuum state.

  This reduces the rotational loss of the flywheel 9 and the squirrel-cage induction motor 10 due to the friction caused by the contact between the rotary shaft 9a and the magnetic bearing 17 and the wind loss from the surrounding atmosphere of the flywheel 9, and the flywheel in the chamber 18. 9, the reduction of the gravity acting on the rotating shaft 9a and the cage induction motor 10 is achieved until the last moment when the rotation of the cage induction motor 10 stops.

  Therefore, according to the uninterruptible power supply 1 of the present embodiment, the time has come when the reduction of rotational loss and gravity does not affect the flywheel 9 and the squirrel-cage induction motor 10 due to the stop of the driving of the magnetic bearing 17 and the vacuum pump 19. It can be delayed as much as possible. This prevents the rotating shaft 9a of the flywheel 9 from colliding with the lower magnetic bearing 17 (or even the upper magnetic bearing 17 in some cases) as much as possible, and a large impact force is exerted on the magnetic bearing 17 due to such collision. It is possible to avoid the damage caused by the addition as much as possible.

  In the uninterruptible power supply 1 of the first embodiment described above, a part of the power supplied from the load inverter 7 to the load 8 is branched to the magnetic bearing drive device 17a and the vacuum pump drive device 19a. It was set as the structure supplied. However, it is also possible to adopt a configuration in which power is supplied to the magnetic bearing driving device 17a and the vacuum pump driving device 19a independently of the power supplied to the load 8. What is configured as such is the uninterruptible power supply according to the second embodiment of the present invention whose configuration is shown in FIG.

  As illustrated in FIG. 7, the uninterruptible power supply 1 </ b> A of the second embodiment is configured such that the transformer 21 is connected to the DC bus 4 via the inverter 23 and the second switch SW <b> 2 is not used. Therefore, in the case of the second embodiment, the part on the load 8 side of the load inverter 7 in the power supply path 3 at the normal time and the power supply path 5 at the time of a power failure is called a dedicated power supply path part for the load 8. It will be.

  Then, the controller 16 of the uninterruptible power supply 1A according to the second embodiment performs processing slightly different from the processing of the flowchart of FIG. 2 performed by the controller 16 of the uninterruptible power supply 1 according to the first embodiment.

  Specifically, after the first switch SW1 is opened in step S5 of the flowchart of FIG. 2, the controller 16 of the uninterruptible power supply 1A proceeds to step S9 as shown in the flowchart of FIG. Judge whether or not. If it is not determined that the power failure has been restored, step S9 is repeated. If it is determined that the power failure has been restored, the first switch SW1 is closed (step S11), and the process is terminated. After completion of the processing, the excitation for power regeneration of the exciting coil of the cage induction motor 10 is terminated, and the power generation by the cage induction motor 10 is terminated. Further, the excitation of the exciting coil of the inverter 23 is also finished, and the power supply to the magnetic bearing driving device 17a and the vacuum pump driving device 19a is finished.

  The same effect as the uninterruptible power supply 1 of the first embodiment can be obtained also by the uninterruptible power supply 1A of the second embodiment having such a configuration.

  Moreover, according to the uninterruptible power supply 1A of the second embodiment, the magnetic bearing driving device 17a and the vacuum pump are connected from the capacitor 15 (DC bus 4) via the inverter 23 independently of the power supplied to the load 8. The driving device 19a is configured to supply power. Therefore, for example, even if an electrical accident or the like occurs on the load 8 side, the power supply to the magnetic bearing driving device 17a and the vacuum pump driving device 19a can be continued regardless of that.

  Therefore, it is possible to prevent the rotation loss and the reduction of gravity from acting on the flywheel 9 and the squirrel-cage induction motor 10 due to an electric accident or the like on the load 8 side due to the drive stop of the magnetic bearing 17 or the vacuum pump 19. it can. For this reason, the rotating shaft 9a of the flywheel 9 is prevented from colliding with the magnetic bearing 17 due to an electric accident or the like on the load 8 side, and a large impact force is applied to the magnetic bearing 17 due to such collision, resulting in damage. Can be avoided.

It is a lineblock diagram of the uninterruptible power supply concerning a 1st embodiment of the present invention. It is a flowchart which shows the procedure of the process performed with the controller of FIG. It is a graph which shows the relationship between the rotation speed of the squirrel-cage induction motor in the electric power generation state by exciting the exciting coil and the voltage of the generated electric power. It is a graph which shows the relationship between the rotation speed of the squirrel-cage induction motor in the electric power generation state by exciting the exciting coil and the electric current of the generated electric power. It is a graph time together with series change in the rotational speed of the squirrel-cage induction motor time series change of power cage induction motor generates power with the power failure.

It is an excitation voltage / excitation current characteristic diagram of an example in which star connection and delta connection are used properly.
It is a graph which shows the relationship between the rotation speed of the squirrel-cage induction motor in the electric power generation state by exciting the exciting coil and the electric current of the generated electric power. It is a block diagram of the uninterruptible power supply device which concerns on 2nd Embodiment of this invention. It is a flowchart which shows the procedure of the process performed with the controller of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,1A Uninterruptible power supply 2 Power supply 3 Power supply path in normal time 4 DC bus 5 Power supply path in power outage 6 Rectifier 7 Load inverter 8 Load 9 Flywheel 9a Rotating shaft 10 Cage induction motor 11 Flywheel inverter 12 Rotation Number meter 13, 22 Ammeter 14 DC voltmeter 15 Capacitor 16 Controller 17 Magnetic bearing 17a Magnetic bearing drive device 18 Chamber 19 Vacuum pump 19a Vacuum pump drive device 21 Transformer 23 Inverter

Claims (5)

Electric power generated by an induction motor that is rotated during a power failure by a flywheel that is rotated during standby is supplied to a load instead of a power source during a power failure, and the electric motor that reduces resistance to rotational motion of the flywheel is reduced. In the flywheel uninterruptible power supply that maintains the operation at the time of a power failure of the movement resistance reducing means by supplying power generated by the induction motor,
When the current value of the electric power generated by the induction motor rises until reaching the rated current value of the induction motor, the induction motor generates power while maintaining the supply of the electric power generated by the induction motor to the motion resistance reducing means. Supply cutoff means for electrically cutting off the supply path to the load of the electric power,
The flywheel type uninterruptible power supply characterized by this.   The supply cutoff means includes an open / close switch interposed on a dedicated supply path for a load of power generated by the induction motor, a current sensor for detecting a current value of power generated by the induction motor, and the current The flywheel system according to claim 1, further comprising a controller that opens the open / close switch that is closed when a current value detected by the sensor increases to a rated current value of the induction motor. Uninterruptible power system.   The supply cut-off means is an open / close switch interposed on a dedicated supply path for a load of power generated by the induction motor, a rotation speed sensor for detecting the rotation speed of the induction motor, and power generated by the induction motor. Controller that opens the open / close switch when the rotation speed detected by the rotation speed sensor per unit time is reduced to a predetermined rotation speed at which the current value of the electric power reaches the rated current value of the induction motor The flywheel uninterruptible power supply apparatus according to claim 1, wherein   4. The flywheel uninterruptible power supply apparatus according to claim 1, wherein the movement resistance reducing means includes a magnetic bearing of a rotary shaft of the flywheel.   The said movement resistance reduction means has the chamber in which the said flywheel is accommodated in interior space, and the decompression device which decompress | depressurizes this interior space, The claim 1, 2, 3, or 4 characterized by the above-mentioned. Flywheel uninterruptible power supply.

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