JP6320343B2 - Drive device for hysteresis motor - Google Patents

Description

  The present invention relates to a drive device for a hysteresis motor that drives a plurality of hysteresis motors in parallel, and particularly relates to a drive device for a hysteresis motor that can restart a power failure for a relatively long time.

  In a hysteresis motor drive device that drives a plurality of hysteresis motors as a load, when a power failure occurs, the load once enters a free-run state. When reconnecting a free-running load with a drive device, restarting at the frequency before the occurrence of an abnormality and connecting all loads, the capacity required for the drive device increases and the device becomes huge. For this reason, a method is introduced in which load connections are made sequentially in a predetermined sequence divided into a plurality of activation groups (see, for example, Patent Document 1). Further, the inventor has proposed a motor drive device that can appropriately reconnect AC motors that are free-running at different rotational speeds between groups and return to a steady state in as short a time as possible (for example, (See Patent Document 2).

JP 2002-204554 A (page 4-5, FIG. 1) JP2013-237833A (Overall)

  In the drive device for hysteresis motor shown in Patent Literature 1 and Patent Literature 2, the drive device (inverter device) does not have or does not have a backup drive device when a failure occurs. A method of reconnecting (restarting) without using this is described. However, in an actual plant, for example, a plurality of drive devices having the same capacity share a hysteresis motor that serves as a load for each motor group, and when one drive device fails, it becomes a backup drive device. The operation is continued by switching. In such a system, it is considered possible to shorten the time for returning to the steady state after power recovery if the backup drive device is effectively used at the time of restart of a power failure. The present invention has been made in view of the above problems, and in a system having a backup drive device, a hysteresis motor drive device having a power failure restarting function capable of returning to a steady state in as short a time as possible. The purpose is to provide.

In order to achieve the above object, a drive device for a hysteresis motor according to the present invention includes a plurality of hysteresis motors for driving a plurality of hysteresis motors via a steady branch switch provided in one to a plurality of motor group units. A stationary inverter device, and one backup inverter device for driving the motor group via a backup branch switch provided for each motor group when one of the stationary inverter devices fails. The power supply to the stationary inverter device and the backup inverter device is temporarily stopped due to a power failure, and the restart procedure after the power recovery is determined according to the power failure time to determine the stationary inverter device, the backup inverter device, and the steady state branch switch And power failure controller for controlling operation of branch switch for backup Comprising a said power failure the controller, if the power failure time is within a predetermined first time, all of the motor group, so as to restart only with the corresponding stationary inverter device, the power failure time is, which when the rotational frequency of restarting of some motor group exceeds a second time such that below a predetermined system incompatible frequency so, so as not to perform a power failure restart, the power failure time is the first When the time exceeds 1 and is less than the second time , at least a part of the motor group is restarted by the stationary inverter device operated at a rated frequency, and the remaining parts of the motor group are sequentially restart in said backup inverter device, as well as to go instead put on the corresponding steady inverter, the first time, the load of the hysteresis motor The second time is calculated from a slip characteristic, a slip torque characteristic, and an overload tolerance of the stationary inverter device, and the second time is a load slip characteristic of the hysteresis motor, a slip torque characteristic, an overload tolerance of the stationary inverter device, and It is characterized in that it is obtained by calculation from the overload capability of the backup inverter device .

  According to the present invention, in a system having a backup drive device, it is possible to provide a hysteresis motor drive device having a power failure restart function capable of returning to a steady state in as short a time as possible.

1 is a system configuration diagram of a hysteresis motor drive device according to Embodiment 1 of the present invention; FIG. Operation | movement explanatory drawing of the drive apparatus for hysteresis motors which concerns on Example 1 of this invention. Operation | movement explanatory drawing of the drive apparatus for hysteresis motors which concerns on Example 2 of this invention. Operation | movement explanatory drawing of the drive apparatus for hysteresis motors concerning Example 3 of this invention.

  Embodiments of the present invention will be described below with reference to the drawings.

  A hysteresis motor drive device according to Embodiment 1 of the present invention will be described below with reference to FIGS.

  FIG. 1 is a system configuration diagram of a hysteresis motor drive device according to Embodiment 1 of the present invention. Inverter devices 1A, 1B, and 1C, which are stationary inverter devices, convert an AC voltage supplied from an AC power source (not shown) into DC by a converter provided therein, and convert the AC voltage into AC again by an inverter and output the AC voltage. The output of the inverter device 1A drives the motor groups 41A and 42A via the branch switches 31A and 32A for steady operation provided in the branch board 3, respectively. The motor group 41A is composed of a plurality of individual switches whose inputs are branched in parallel, and hysteresis motors 51A,... The motor group 42A is basically configured similarly to the motor group 41A, and is not shown. The output of the inverter device 1B drives the motor groups 41B and 42B via the branch switches 31B and 32B for steady operation provided in the branch board 3, respectively. The motor group 41B is composed of a plurality of individual switches whose inputs are branched in parallel, and hysteresis motors 51B,. The motor group 42B is basically configured similarly to the motor group 41B, and is not shown. Similarly, the output of the inverter device 1C drives the motor groups 41C and 42C via the branch switches 31C and 32C for steady operation provided in the branch board 3, respectively. The motor group 41C is composed of a plurality of individual switches whose inputs are branched in parallel, and hysteresis motors 51C,. The motor group 42C is basically configured similarly to the motor group 41C, and is not shown. In the branch board 3, filter devices for power factor improvement and waveform improvement are usually provided corresponding to each motor group, but these are not shown. Also, a plurality of individual switches that branch the inputs in parallel may be omitted.

  The output of the backup inverter device 2 is supplied to the motor groups 41A, 42A, 41B, 42B, 41C and 42C via the branch switches 33A, 34A, 33B, 34B, 33C and 34C for backup operation provided in the branch board 3, respectively. It is comprised so that it can drive. For example, when the inverter device 1A fails, the branch switches 31A and 32A are turned off, the branch switches 33A and 34A are turned on, and the motor groups 41A and 42A are driven by the backup inverter device 2.

  The power failure controller 6 monitors a power failure and a power recovery of an AC power supply of an input system (not shown), determines a restart procedure according to the power failure time, inverter devices 1A, 1B, 1C, a backup inverter device 2, a branch board 3 An operation command or an on / off command is given to each branch switch provided in the inside. Moreover, as will be described later, an operation frequency command for the backup inverter device 2 at the time of restart of the power failure is given as necessary.

  The inverter devices 1A, 1B, 1C and the backup inverter device 2 have a control device that performs normal control, but this illustration is omitted in FIG. In FIG. 1, it has been described that the power failure controller 6 detects power failure and power recovery, but each of the inverter devices 1A, 1B, 1C and the backup inverter device 2 performs power failure detection and autonomously with power recovery. The operation may be started.

  Next, the operation will be described with reference to the operation explanatory diagram (operation time chart) of FIG. Assume that a power failure occurs at time t = T1 in a state where all the motor groups 41A, 42A, 41B, 42B, 41C, and 42C are operated at the rated frequency in the inverter devices 1A, 1B, and 1C. When the power failure controller 6 detects this power failure, the power failure controller 6 opens the branch switches 31A, 32A, 31B, 32B, 31C, 32C and free-runs the motor groups 41A, 42A, 41B, 42B, 41C, 42C. Let

  Next, it is assumed that the power supply is restored at time t = T2. At this time, when the power failure time Tf = T2-T1 is smaller than the predetermined time Tt, the power failure controller 6 gives a re-operation command to the inverter devices 1A, 1B, 1C as it is, and branches switches 31A, 32A, 31B, 32B, 31C, and 32C are turned on again to restart the motor groups 41A, 42A, 41B, 42B, 41C, and 42C. The output torque and input current based on the slip characteristics of the hysteresis motor during restart are considerably larger than those during rated operation, and therefore the inverter devices 1A, 1B, 1C are used in the overload region, for example, the inverter device 1A, If the overload capability of 1B and 1C is 200% -1 minutes, Tt can be obtained in advance from the load-slip characteristics of the hysteresis motor. Here, the load-slip characteristic means a deceleration characteristic determined from the inertia moment of the hysteresis motor and the speed characteristic of the load.

  The operation time chart of FIG. 2 shows a case where the power failure time Tf = T2−T1 exceeds a predetermined time Tt. The operation will be described below.

  When a power failure occurs at time t = T1 and power is restored at time t = T2, a re-operation command is given to the inverter devices 1A, 1B, 1C and a re-operation command is also given to the backup inverter 2. At substantially the same time, the branch switches 31A, 31B, and 31C are turned on again to restart the motor groups 41A, 41B, and 41C, and the branch switch 34A is turned on to restart the motor group 42A with the backup inverter device 2. . In this case, the output frequency of all inverters is the rated frequency fN.

  Then, the power failure controller 6 calculates a time T3 at which the electric motor group 42A can be turned on to the inverter device 1A by calculation, opens the branch switch 34A at time T3, and turns on the branch switch 32A immediately thereafter. The method for obtaining T3 is based on the following concept.

  The inverter device 1A restarts the motor group 41A at time T2, but the slip of the hysteresis motor of the motor group 41A decreases with the passage of time, and thus the load current decreases. That is, the restart capacity Pn that can be newly loaded with time increases with the passage of time. On the other hand, the motor group 42A restarted by the backup inverter device 2 at time T2 also decreases the slip of the hysteresis motor as time passes. Therefore, the restart capacity Pf when the motor is restarted after being free-runned is decreased. To go. These time functions Pn and Pf can be easily obtained by calculation if the load slip characteristics and slip torque characteristics of the hysteresis motor are known, and T3 can be obtained from the condition that Pn> Pf. That is, when the power failure time T2−T1 = Tf is slightly longer than the predetermined time Tt, the above condition is achieved in a short time, so that T3 becomes a value close to T2, and T3 becomes larger as Tf becomes larger than Tt. .

  When the branch switch 34A is opened at time T3, the backup inverter device 2 becomes empty, so the branch switch 34B is immediately turned on to restart the motor group 42B with the backup inverter device 2. Then, the power failure controller 6 calculates a time T4 at which the electric motor group 42B can be turned on to the inverter device 1B by calculation, opens the branch switch 34B at time T4, and turns on the branch switch 32B immediately thereafter. Here, the time T4 can be obtained by the same method as the time T3. Similarly, the branch switch 34C is turned on at time T4 to restart the motor group 42C with the backup inverter device 2. Then, the power failure controller 6 calculates a time T5 at which the electric motor group 42C can be turned on to the inverter device 1C by calculation, opens the branch switch 34C at time T5, and turns on the branch switch 32C immediately thereafter. After time T5, the motor group 42C accelerates and completes acceleration at time T6. At this time T6, all the motor groups are operated at the rated speed.

  In the above description, when the rotational frequency of the motor group 42C at the time T5 falls below a predetermined rotational frequency corresponding to the system incompatibility frequency, a problem may occur in the entire system. It is. As described above, if power failure time Tf is determined, T3, T4, and T5 can be obtained by calculation, and the operating speed of motor group 42C at time T5 can be easily obtained from the load-slip characteristics. That is, since the power failure time TfL at which the operation speed of the motor group 42C at the time T5 becomes a predetermined operation speed is uniquely determined, it is possible to prevent the system from restarting when the power failure time Tf> TfL. It becomes.

  FIG. 3 is an operation explanatory diagram of the hysteresis motor drive device according to Embodiment 2 of the present invention. The second embodiment shows an example of a restart method when the backup inverter device 2 is used as VVVF.

  In FIG. 3, a power failure occurs at time T1, power is restored at time T2, and then the branch switches 31A, 31B, and 31C are turned on again to restart the motor groups 41A, 41B, and 41C. The process until the motor group 42A is restarted by the backup inverter device 2 after turning on 34A is exactly the same as in FIG.

  The difference is the operating frequency of the backup inverter device 2 when the motor group 42A is opened at the time T2 and the branch switch 32A is turned on immediately after that to restart the motor group 42A. The frequency f1 at this time is set and changed so as to be equivalent to the rotational frequency of the motor group 42A that has been reduced to a free run due to a power failure. As described above, the frequency f1 is obtained from the load slip characteristic of the hysteresis motor.

  Then, as shown in the lower part of FIG. 3, the backup inverter device 2 accelerates at the maximum acceleration rate that does not cause the slip of the hysteresis motor of the motor group 42A, and the operation frequency becomes fT at time t = T3 ′. At that time, the branch switch 34A is opened, and immediately after that, the branch switch 32A is turned on. Note that fT ≦ fN, where fN is the steady-state operating frequency. In addition, when such a synchronous acceleration method is used, the burden on the backup inverter device 2 is reduced, but the acceleration torque of the hysteresis motor is also reduced by that amount, and therefore it is normal that T3 '> T3.

  Thereafter, as in the case of the first embodiment, the backup inverter device 2 becomes empty at time T3 ′, so the branch switch 34B is immediately turned on and the motor group 42B is restarted by the backup inverter device 2. The frequency of the backup inverter device 2 at this time is the frequency f2 corresponding to the time T3 '. Here, f2 <f1. Similarly, the motor group 42B is synchronously accelerated. When the operating frequency reaches fT at time t = T4 ', the branch switch 34B is opened, and immediately after that, the branch switch 32B is turned on.

  Similarly, at time T4 ', the branch switch 34C is turned on to restart the motor group 42C with the backup inverter device 2. The operating frequency at this time is f3. Similarly, the motor group 42C is synchronously accelerated, the branch switch 34C is opened at time T5 ', and the branch switch 32C is turned on immediately thereafter. After time T5 ', the motor group 42C accelerates and completes acceleration at time T6'. At this time T6 ', all the motor groups are operated at the rated speed.

  In such a second embodiment, T6 '> T6 as compared with the first embodiment, so that the power failure recovery time becomes longer and there seems to be no merit. In fact, this is the case when two or more groups can be switched between the stationary inverter device and the backup inverter device, such as the motor group 41A and the motor group 41B. However, unlike the system of FIG. 1, for example, when there is only one motor group for the stationary inverter device, when the power failure time Tf exceeds a predetermined time Tt, all the motor groups are as shown in FIG. In addition, it is necessary to sequentially synchronize with the backup inverter device 2 and transfer to the stationary inverter device. Advantages of the second embodiment include that the restart capacity of the backup inverter 2 at the time of restart is small, and that the heat generation of the hysteresis motor at the time of restart can be reduced.

  FIG. 4 is a diagram for explaining the operation of the hysteresis motor drive device according to Embodiment 3 of the present invention. In the third embodiment, if there is a condition, a method for further shortening the restart time is provided.

  As shown in FIG. 4, when power is restored at t = T2, the branch switches 31A, 31B, and 31C are turned on and the motor groups 41A, 41B, and 41C are respectively connected to the inverter devices 1A, 1B as in the first and second embodiments. And restart at 1C. Then, in addition to the branch switch 34A, the branch switch 34B is also turned on at the same time to restart the motor groups 42A and 42B with the backup inverter device 2. The restart frequency at this time is assumed to be f1 shown in FIG. Similarly to the case of the second embodiment, the motor groups 42A and 42B are synchronously accelerated by the backup inverter device 2, and when the drive frequency becomes fT at time T3 ′, the branch switches 34A and 34B are opened, and the branch switches 32A and 32B are opened. The electric motor groups 42A and 42B are reconnected to the inverter devices 1A and 1B, respectively.

  Then, at time T3 ', the branch switch 34C is turned on to restart the motor group 42C with the backup inverter device 2. The restart frequency at this time is f2 if learned from the second embodiment. In that case, when the drive frequency becomes fT at time T4 ', the branch switch 32C is turned on to reconnect the motor group 42C to the inverter device 1C. In this way, if the motor groups connected to different inverter devices can be restarted simultaneously by the backup inverter device 2, the restart time is greatly shortened. Also, if the branch switch 34C is turned on at time T3 ′ and the drive frequency when the motor group 42C is restarted by the backup inverter device 2 is slid and accelerated at the rated frequency, T4 ′ in FIG. 4 is further shortened. Obviously.

  Although several embodiments have been described above, these embodiments are presented as examples, and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  For example, FIG. 1 shows a case where there are three stationary inverter devices, but the same applies to any plurality of inverter devices.

  Further, in FIG. 1, for the sake of simplicity, the motor groups connected to each inverter device are two identical capacities, but the number of motor groups and the capacity ratio thereof are arbitrary. As described in the second embodiment, even when there is only one motor group connected to the stationary inverter device, if the backup inverter device is used effectively, the power failure time that can restart the power failure as a system is extended. It becomes possible.

  In addition, when the number of motor groups is three or more, or when the motor groups are not of the same capacity, the motor group that is restarted as it is with the steady inverter device so that the time required for the power failure restart as a system is minimized. Then, the backup inverter device 2 is divided into the remaining motor groups that are slidingly restarted or synchronously accelerated. For example, when there are three stationary inverter devices and three motor groups with the same capacity, the two motor groups are restarted as they are in each stationary inverter device, and the remaining three motor groups are synchronously accelerated at once. By doing so, it is possible to greatly shorten the time required for the system to restart after a power failure.

  Further, in the second embodiment, it has been described that the restart frequencies f1, f2, and f3 are obtained from the load-slip characteristics of the hysteresis motor. However, for each motor group, a detector that obtains the frequency of the reverse voltage during the free run is provided. The detected frequency may be the restart frequency.

1A, 1B, 1C Inverter device 2 Backup inverter device 3, 31A, 31B, 31C, 32A, 32B, 32C, 33A, 33B, 33C Branch switch 41A, 42A, 41A, 42B, 41C, 42C Motor group 51A, ... 5NA ... 51B ... 5NB ... 51C ... 5NC Hysteresis motor 6 Power failure controller

Claims (4)

A plurality of stationary inverter devices for driving a plurality of hysteresis motors via a branch switch for stationary operation provided in one to a plurality of motor group units;
When one of the inverter devices fails, one backup inverter device for driving the motor group via a backup branch switch provided for each motor group;
The power supply to the stationary inverter device and the backup inverter device is temporarily stopped due to a power failure, and the restart procedure after the power recovery is determined according to the power failure time to determine the stationary inverter device, the backup inverter device, the steady state branch switch, and A power failure controller for controlling the operation of the branch switch for backup,
The power failure controller is
If the power failure time is within a predetermined first time, all the motor groups are restarted only with the corresponding stationary inverter device,
When the power failure time exceeds a second time such that the rotational frequency of some of the motor groups is equal to or lower than a predetermined system non-conformance frequency regardless of how the power failure is restarted, the power failure restart is not performed.
Exceeds the outage time is the first time, the time is less than the second time, the part most of the motor group along with restart in the stationary inverter device is operated at the rated frequency, the motor group And sequentially restart the remaining part of the backup inverter device, and transfer to the corresponding stationary inverter device ,
The first time is obtained by calculation from the load slip characteristics of the hysteresis motor, the slip torque characteristics, and the overload capability of the stationary inverter device,
The second time is obtained by calculation from a load slip characteristic, a slip torque characteristic of the hysteresis motor, an overload resistance of the stationary inverter device, and an overload resistance of the backup inverter device. Drive device for electric motors. The power failure controller is
If the power outage time exceeds the first time and is less than the second time,
When the remaining portions of the group of motors are sequentially restarted by the backup inverter device, the frequency obtained from the load-slip characteristics of each motor group is set as the restart frequency of the backup inverter device, and synchronous acceleration is performed up to a predetermined frequency. The hysteresis motor drive device according to claim 1, wherein the hysteresis motor drive device is changed over to a corresponding inverter device after that. The power failure controller is
If the power outage time exceeds the first time and is less than the second time,
Restarting a part of the motor group with the stationary inverter device operating at the rated frequency and restarting the remaining part of the motor group with the backup inverter device operating at the rated frequency sequentially. The drive device for a hysteresis motor according to claim 1, wherein the drive device is a hysteresis motor. The power failure controller is
If the power outage time exceeds the first time and is less than the second time,
In order to minimize the overall restart time, select a motor group when restarting with the stationary inverter device, and if a plurality of remaining motor groups can be restarted simultaneously, this is done. The drive device for a hysteresis motor according to claim 1, wherein the drive device is a hysteresis motor.