JP2011205898A - Motor drive system and control method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motor drive system and a control method thereof for restarting a motor reliably with a simpler structure than before, while preventing a failure during reconnection between an inverter and a motor.SOLUTION: The motor drive system 1 includes an inverter 2, a first switch 3, and a control section 4. The inverter 2 drives the motor. The first switch 3 is connected between the output side of the inverter 2 and the motor. The control section 4 controls the inverter 2 and the first switch 3. The control section 4 shuts off the output of the inverter 2 by the first switch 3 when a failure occurs in a commercial power supply or the motor drive system 1. The control section 4 stops the inverter 2. The control section 4 turns on the first switch 3. The control section 4 starts operation of the inverter 2 after the lapse of a predetermined operation start delay time.

Description

  The present invention relates to a motor drive system for controlling an inverter of a motor and a control method thereof.

  As a motor drive system used for reducing the inverter capacity, for example, there is a motor drive system represented by an electric motor operation system for switching between an inverter and a commercial power supply direct line. This motor drive system comprises an inverter having an electromagnetic switch or an electromagnetic contactor (hereinafter referred to as a switch) connected to the output side, a motor driven by the inverter, an abnormality detection means, and a control means for controlling them. Has been. In such a motor drive system, when the abnormality detection means detects some abnormal state and stops the switch and the inverter and then returns the system, it has the following problems.

  In general, an inverter circuit takes a longer time to stop than a switch or the like. Therefore, when the stop time is short, the switch or the like may perform a shut-off operation and a restart operation without stopping the inverter circuit completely. .

  Also, since inverters generally perform optimal control in accordance with the rotational state of the motor, if the shut-off operation and re-input operation are performed on the inverter output side, the rotational state of the motor becomes discontinuous. An abnormal state such as overcurrent / overvoltage may occur at the time of turning on, and in some cases, the inverter or the motor may be broken.

  In order to solve such a problem, for example, a method for restarting the electric motor called “pick-up” has been studied.

  For example, a method of determining the operation at the time of restart based on the residual voltage of the induction motor represented by Patent Document 1 (Patent No. 2793384) or by induced voltage phase detection represented by Patent Document 2 (Patent No. 3123220) The PM motor restart method can solve the above problem.

  However, in the start-up methods described in Patent Documents 1 and 2, the arithmetic unit is complicated, so that the motor is reliably restarted with a simple configuration, and at the same time, an abnormality when the inverter and the motor are reconnected is prevented. It is difficult.

  In addition, since the starting methods described in Patent Documents 1 and 2 depend on the specifications of the inverter, there is a disadvantage that choices are limited on the use side.

  As described above, there are design restrictions and the product operation is adversely affected.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a motor drive system and a control method thereof capable of reliably restarting a motor with a simpler configuration than before and capable of preventing abnormalities when reconnecting an inverter and a motor. It is in.

The motor drive system according to the first invention includes an inverter, a first switch, and a control unit. The inverter drives a motor. The first switch is connected between the output side of the inverter and the motor. The control unit controls the inverter and the first switch. A control part performs the interruption | blocking operation | movement which interrupts | blocks the output of an inverter with a 1st switch, when a commercial power source or a motor drive system becomes an abnormal state. Thereafter, the control unit performs a stop operation for stopping the inverter. After then passed Oite predetermined connection delay time, the control unit performs the connection operation for connecting the first switch. Further thereafter, the control unit performs an operation start operation for starting the operation of the inverter after a predetermined operation start delay time has elapsed. The connection delay time is set to such a time that the inverter overcurrent protection or overvoltage protection does not work when the motor is restarted, based on the rotational speed reduction characteristic when the motor is powered off.

  Here, when the commercial power source or the motor drive system is in an abnormal state, the control unit performs a shut-off operation to shut off the output of the inverter by the first switch, and then performs a stop operation to stop the inverter. In addition, a connection operation for connecting the first switch is performed, and then an operation start operation for starting the operation of the inverter after the elapse of a predetermined operation start delay time is performed. It is possible to restart. At the same time, it is possible to prevent an abnormality when the inverter and the motor are reconnected.

  In addition, since the control unit controls the connection operation to be performed after a predetermined connection delay time has elapsed after the stop operation, the motor can be restarted more reliably. At the same time, it is possible to more reliably prevent an abnormality when the inverter and the motor are reconnected.

  Further, the connection delay time is set to such a time that the inverter overcurrent protection or overvoltage protection does not work when the motor is restarted, based on the rotational speed reduction characteristic when the motor is powered off. Thereby, it is possible to ensure the rotation speed reduction time suitable for each motor. Therefore, the motor can be restarted more reliably, and at the same time, it is possible to more reliably prevent an abnormality when the inverter and the motor are reconnected.

  The motor drive system of the second invention is the motor drive system of the first invention, and the operation start delay time is determined by the connection of the first switch after the connection start signal is input to the first switch in the connection operation. It is set to a time longer than the time until completion.

  Here, since the operation start delay time is set to a time longer than the time from when the connection start signal is input to the first switch in the connection operation until the connection of the first switch is completed, the first It is possible to secure time until the switch is connected. Therefore, the motor can be restarted more reliably, and at the same time, it is possible to more reliably prevent an abnormality when the inverter and the motor are reconnected.

The motor drive system of the third invention is the motor drive system of the first invention, and the connection delay time is a time from the end of the abnormal state to the start of the connection operation.

  Here, since the connection delay time is the time from the end of the abnormal state to the start of the operation of the connection operation, the motor can be restarted more reliably, and at the same time, the abnormality at the time of reconnection of the inverter and the motor Can be more reliably prevented.

The motor drive system according to a fourth aspect is the motor drive system according to the first aspect , wherein the connection delay time is a time from the start of the abnormal state to the start of the connection operation.

  Here, since the connection delay time is the time from the start of the abnormal state to the start of the operation of the connection operation, the motor can be restarted more reliably, and at the same time, the abnormality at the time of reconnection of the inverter and the motor Can be more reliably prevented.

A motor drive system according to a fifth aspect of the present invention is the motor drive system according to the first aspect of the present invention, wherein the connection delay time is a time from when the first switch is turned off to when the connection operation starts.

Here, since the connection delay time is the time from when the first switch is shut off until the start of the connection operation, the motor can be restarted more reliably and at the same time when the inverter and the motor are reconnected. It is possible to more reliably prevent abnormalities in .

A motor drive system according to a sixth aspect of the present invention is the motor drive system according to the first aspect of the present invention, further comprising a rotation speed measuring means. The rotational speed measuring means measures the rotational speed of the motor. The operation start delay time is a time until the rotational speed of the motor becomes less than a predetermined value after the first switch is connected.

  Here, the motor drive system further includes a rotation speed measuring means for measuring the rotation speed of the motor, and the operation start delay time is set to a time until the rotation speed of the motor becomes less than a predetermined value after the first switch is connected. Therefore, the motor can be restarted more reliably, and at the same time, it is possible to more reliably prevent an abnormality when the inverter and the motor are reconnected.

A motor drive system according to a seventh aspect is the motor drive system according to any one of the first to sixth aspects, further comprising a direct line and a second switch. The direct line connects the commercial power supply directly to the motor. The second switch opens and closes the direct line.

  Here, the motor drive system further includes a direct line that directly connects the commercial power source to the motor and a second switch that opens and closes the direct line. Therefore, the AC power of the commercial power source is directly sent to the motor to drive the motor. It is possible to drive.

A motor drive system according to an eighth aspect of the present invention is the motor drive system according to any one of the first to seventh aspects, further comprising a switching unit. The switching unit switches power supply to the motor to either the commercial power source or the generator. The generator is different from the commercial power source.

  Here, since the motor drive system further includes a switching unit, the power supply to the motor can be switched to either the commercial power source or the generator different from the commercial power source. Therefore, even when the commercial power source cannot be used, the motor can be driven by the generator.

A motor drive system according to a ninth aspect is the motor drive system according to any one of the first to sixth aspects, further comprising a direct line and a second switch. A direct line connects the generator directly to the motor. The second switch opens and closes the direct line. The generator is different from the commercial power source.

Here, the motor drive system further includes a direct line that directly connects the generator different from the commercial power source to the motor, and a second switch that opens and closes the direct line, so even when the commercial power source is unusable, It is possible to drive the motor with a generator .

According to the first aspect of the invention, the motor can be reliably restarted with a simpler configuration than in the prior art. At the same time, abnormalities at the time of reconnection of the inverter and the motor can be prevented. Thereby, stable product operation is possible. It is also possible to secure a rotation speed reduction time suitable for each motor.

According to the second invention, it is possible to secure time until the first switch is completely connected. Therefore, the motor can be restarted more reliably. At the same time, it is possible to more reliably prevent an abnormality when the inverter and the motor are reconnected.

  According to the third invention, the motor can be restarted more reliably. At the same time, it is possible to more reliably prevent an abnormality when the inverter and the motor are reconnected.

  According to the fourth invention, the motor can be restarted more reliably. At the same time, it is possible to more reliably prevent an abnormality when the inverter and the motor are reconnected.

According to the fifth aspect, the motor can be restarted more reliably. At the same time, it is possible to more reliably prevent an abnormality when the inverter and the motor are reconnected .

According to the sixth aspect of the invention, the motor can be restarted more reliably. At the same time, it is possible to more reliably prevent an abnormality when the inverter and the motor are reconnected.

According to the seventh aspect , the AC power of the commercial power supply can be directly sent to the motor to drive the motor.

According to the eighth aspect of the invention, the motor can be driven by the generator even when the commercial power source is not usable.

According to the ninth aspect of the invention, the motor can be driven by the generator even when the commercial power source cannot be used .

1 is an overall configuration diagram of a motor drive system according to a first embodiment of the present invention. The circuit block diagram of the inverter of FIG. The graph which represented the operation | movement of the motor drive system of FIG. 1 by the time series change. The flowchart of the control method of the motor drive system of FIG. The graph which represented the operation | movement of the motor drive system concerning the modification of this invention by the time series change. The whole block diagram of the motor drive system concerning the other modification of this invention. The flowchart of the control method of the motor drive system concerning 2nd Embodiment of this invention.

[First Embodiment]
A motor drive system 1 shown in FIG. 1 includes an inverter 2, a first switch 3, a control unit 4, a direct line 5, a second switch 6, and a switching unit 7. The motor drive system 1 is connected to two AC power sources, that is, a commercial power source AP and an engine generator EP on the input side, and connected to a motor M that is an AC induction motor on the output side.

  The inverter 2 adjusts the AC power supplied from the commercial power supply AP and the engine generator EP, and supplies the AC power to the motor M that is an AC current generator, thereby adjusting the operating frequency of the motor M.

  As shown in FIG. 2, the inverter 2 includes a converter unit 11, a smoothing capacitor 12, and an inverter unit 13.

  The converter unit 11 is a part that converts AC power into DC power, and includes a plurality of diodes 14. In the converter unit 11 shown in FIG. 2, two diodes 14 are made into one set, and three sets of diode rows are connected in parallel to each other.

  The smoothing capacitor 12 is an electrolytic capacitor.

  The inverter unit 13 has a plurality of semiconductor switches 15. Each of the semiconductor switches 15 includes a switching element 17 and a diode 16 connected in antiparallel to the switching element 17. In the inverter unit 13 shown in FIG. 2, two semiconductor switches 15 are made into one set, and three sets of semiconductor switch rows are connected in parallel to each other.

  The first switch 3 opens and closes a connection line between the inverter 2 and the motor M. As shown in FIG. 1, the first switch 3 is provided at each of the three terminals (U, V, W) on the output side of the inverter 2. The 1st switch 3 is comprised from the electromagnetic switch or the electromagnetic contactor.

  The direct line 5 connects the commercial power supply AP and the motor M so as to bypass the inverter 2. The direct line 5 has three electric wires for transmitting AC power.

  The second switch 6 opens and closes the direct line 5. The 2nd switch 6 is comprised from the electromagnetic switch or the electromagnetic contactor.

  The switching unit 7 switches power supply to the motor M to either the commercial power source AP or the engine generator EP. The engine generator EP is an engine-driven generator different from the commercial power supply AP.

  The branch line 8 connects the commercial power supply AP and the switching unit 7.

<Description of control unit 4>
The control unit 4 controls the operation of the inverter 2 and the first switch 3. Note that the control unit 4 may be included in the inverter 2.

  When the commercial power source AP or the motor drive system 1 is in an abnormal state, the control unit 4 performs a blocking operation for blocking the output of the inverter 2 by the first switch 3. Thereafter, the control unit 4 performs a stop operation for stopping the inverter 2. Thereafter, the control unit 4 performs a connection operation for connecting the first switch 3. Further thereafter, the control unit 4 performs an operation start operation for starting the operation of the inverter 2 after a predetermined operation start delay time T2 (see FIG. 3) has elapsed. As a result, the motor M can be reliably restarted with a simpler configuration than before, and at the same time, it is possible to prevent an abnormality when the inverter 2 and the motor M are reconnected.

  As other effects, the dependence on the inverter specifications is smaller than in the prior art, and the degree of freedom in design on the control side is increased.

  The control unit 4 can also detect an abnormality in the commercial power supply AP or the motor drive system 1 by monitoring input / output power of the motor drive system 1 and the like. Note that an abnormality detection means for detecting an abnormality in the commercial power supply AP or the motor drive system 1 may be provided in the motor drive system 1 separately from the control unit 4.

The operation start delay time T2 is set to a time longer than the time from when the connection start signal is input to the first switch 3 in the connection operation until the connection of the first switch 3 is completed. The unit 4 controls to perform the connection operation after a predetermined connection delay time T1 (see FIG. 3) has elapsed after the stop operation.

  As shown in FIG. 3, the connection delay time T1 is a time from the end time t2 of the abnormal state to the operation start time t3 of the connection operation.

  The connection delay time T1 is set based on the rotational speed reduction characteristic when the motor M is powered off. As the rotational speed reduction characteristic, for example, when the motor M is rotating at a predetermined rotational speed (for example, about 1000 to 1200 rpm) and the first switch 3 is shut off when an abnormality occurs, the motor M is immediately Without stopping, the number of revolutions decreases with the passage of time. After 5 seconds, the speed decreases to about 200 rpm, and after 10 seconds, the speed decreases to about 100 rpm.

<Control method of motor drive system 1>
The control method of the motor drive system 1 configured as described above is performed according to the procedure shown in the graph of FIG. 3 and the flowchart of FIG.

  First, as shown in step S1 in the flowchart of FIG. 4, the control unit 4 detects an abnormality in the commercial power supply AP or the motor drive system 1.

  Next, as shown in step S2, the control unit 4 performs a blocking operation for blocking the output of the inverter 2 by the first switch 3 when the commercial power source AP or the motor drive system 1 detects an abnormal state.

  Next, as shown in steps S <b> 3 to S <b> 5, the control unit 4 subsequently performs a stop operation for stopping the inverter 2.

  Specifically, first, in step S <b> 3, the control unit 4 transmits a stop command to the inverter 2.

  Next, as shown in step S4, the control unit 4 detects the abnormality release.

  Then, as shown in step S5, the control unit 4 transmits a stop command to the inverter 2 again after detecting the abnormality release in step S4.

  Thus, by performing the stop operation shown in steps S3 to S5, a sufficient stop time of the inverter 2 can be secured, so that the motor M can be reliably restarted. In addition, it is possible to suppress the occurrence of abnormality due to the occurrence of overcurrent or overvoltage when the switch 3 is turned on again thereafter.

  In steps S3 to S5, if the stop state of the inverter 2 continues before and after the abnormality is released, the control unit 4 again performs the operation in step S5, that is, after detecting the abnormality removal in step S4. The operation of transmitting a stop command to the inverter 2 may not be performed. Also in this case, it is possible to reliably restart the motor M and to suppress the occurrence of abnormality due to the occurrence of overcurrent or overvoltage.

  Next, as shown in step S6, the control unit 4 waits for a predetermined connection delay time T1 (see FIG. 3).

  Next, as shown in step S <b> 7, the control unit 4 performs a connection operation for connecting the first switch 3 thereafter. The control unit 4 connects the output of the inverter 2 by turning on the switch 3.

  Next, as shown in step S8, the control unit 4 waits for a predetermined operation start delay time T2 (see FIG. 3).

  Thereafter, as shown in step S <b> 9, the control unit 4 performs an operation start operation for starting the operation of the inverter 2. Specifically, the control unit 4 transmits an operation command to the inverter 2 to start the operation of the inverter 2.

<Features of First Embodiment>
(1)
In the motor drive system 1 according to the first embodiment, the control unit 4 performs a shut-off operation of shutting off the output of the inverter 2 by the first switch 3 when the commercial power supply AP or the motor drive system 1 is in an abnormal state. Thereafter, a stop operation for stopping the inverter 2 is performed, and thereafter, a connection operation for connecting the first switch 3 is performed, and thereafter, the operation of the inverter 2 is started after a predetermined operation start delay time T2 has elapsed. The operation start operation is performed. Therefore, the motor M can be reliably restarted with a simpler configuration than before, and at the same time, it is possible to prevent an abnormality when the inverter and the motor are reconnected.

  In addition, this configuration makes the dependence on the inverter specification smaller than before, and increases the degree of design freedom on the control side.

(2)
In the motor drive system 1 according to the first embodiment, the control unit 4 controls the connection operation to be performed after a predetermined connection delay time T1 has elapsed after the stop operation, so that the motor M can be more reliably restarted. At the same time, it is possible to more reliably prevent an abnormality when the inverter and the motor are reconnected.

(3)
In the motor drive system 1 according to the first embodiment, the connection delay time T1 is the time from the end t2 of the abnormal state to the start time t3 of the connection operation, as shown in FIG. It is possible to restart more reliably, and at the same time, it is possible to more reliably prevent an abnormality when the inverter and the motor are reconnected.

(4)
In the motor drive system 1 according to the first embodiment, the connection delay time T1 is set based on the rotational speed reduction characteristic when the power of the motor M is cut off. Therefore, the rotational speed reduction time suitable for each motor M is set. Can be secured. Therefore, the motor M can be restarted more reliably, and at the same time, it is possible to more reliably prevent an abnormality when the inverter and the motor are reconnected.

(5)
In the motor drive system 1 according to the first embodiment, the operation start delay time T2 is the time from when the connection start signal is input to the first switch 3 in the connection operation until the connection of the first switch 3 is completed. Is set to a longer time, it is possible to secure a time until the first switch 3 is completely connected. Therefore, the motor M can be restarted more reliably, and at the same time, it is possible to more reliably prevent an abnormality when the inverter and the motor are reconnected.

(6)
The motor drive system 1 according to the first embodiment further includes a direct line 5 that directly connects the commercial power source AP to the motor M, and a second switch 6 that opens and closes the direct line 5. It is possible to drive the motor M by sending AC power directly to the motor M.

(7)
Since the motor drive system 1 according to the first embodiment further includes a switching unit 7 for switching power feeding, the motor M is provided in either the commercial power source AP or the engine generator EP different from the commercial power source AP. It is possible to switch the power supply to. Therefore, even when the commercial power supply AP cannot be used, it is possible to drive the motor M using AC power supplied from the engine generator EP.

(8)
The control method of the motor drive system 1 according to the first embodiment includes a shut-off operation in which the output of the inverter 2 is shut off by the first switch 3 when the commercial power supply AP or the motor drive system 1 is in an abnormal state, and the inverter 2 A stop operation for stopping the operation, a connection operation for connecting the first switch 3, and an operation start operation for starting the operation of the inverter 2 after a predetermined operation start delay time T <b> 2 has elapsed. Thus, the motor can be reliably restarted, and at the same time, it is possible to prevent an abnormality when the inverter 2 and the motor M are reconnected.

  In addition, this configuration makes the dependence on the inverter specification smaller than before, and increases the degree of design freedom on the control side.

<Modification of First Embodiment>
(A)
In the motor drive system 1 according to the first embodiment, the connection delay time T1 is the time from the end time t2 of the abnormal state to the start time t3 of the connection operation, but the present invention is not limited to this.

  As a modification of the first embodiment, the connection delay time T3 may be a time from the start time t1 of the abnormal state to the operation start time t3 of the connection operation, as shown in the graph of FIG. Also in this case, the motor M can be restarted more reliably, and at the same time, an abnormality at the time of reconnection between the inverter and the motor can be more reliably prevented.

  When the connection delay time T3 of FIG. 5 (that is, the connection delay time from the start time t1 of the abnormal state to the operation start time t3 of the connection operation) is adopted, steps S4 and S5 in the flowchart shown in FIG. 4 are omitted. it can. Therefore, the motor drive system 1 can be controlled with a simpler control program.

(B)
In addition, since there is a delay from the start of the abnormal state to the disconnection of the first switch 3, as another modification of the first embodiment, the connection delay time T3 is connected from the time when the first switch 3 is disconnected. It may be the time until the operation start time t3 of the operation. Also in this case, the motor M can be restarted more reliably, and at the same time, an abnormality at the time of reconnection between the inverter and the motor can be more reliably prevented.

(C)
In the motor drive system 1 according to the first embodiment, the connection delay time T1 is set based on the rotational speed reduction characteristic when the motor M is powered off, but the present invention is not limited to this.

  As another modification of the first embodiment, the connection delay time T1 may be set to a time at which the overcurrent protection or overvoltage protection of the inverter 2 does not work when the motor M is restarted. Also in this case, the motor M can be restarted more reliably, and at the same time, an abnormality at the time of reconnection between the inverter and the motor can be more reliably prevented.

(D)
In the motor drive system 1 according to the first embodiment, the operation start delay time T2 is from the connection start signal input to the first switch 3 in the connection operation until the connection of the first switch 3 is completed. However, the present invention is not limited to this.

  As still another modified example of the first embodiment, the motor drive system 1 further includes a rotation speed measurement unit that measures the rotation speed of the motor M, and the operation start delay time T2 is determined after the first switch 3 is connected. It may be set so that it is the time until the number of rotations becomes less than a predetermined value.

  Even in this case, the motor M can be restarted more reliably, and at the same time, it is possible to more reliably prevent an abnormality when the inverter and the motor are reconnected.

  The rotation speed measuring means is, for example, a rotary encoder provided on the rotation shaft of the motor M.

  For example, from the state where the motor M is rotating at a predetermined rotation speed (for example, about 1000 to 1200 rpm), when the first switch 3 is shut off at the time of occurrence of an abnormality, the motor M does not stop immediately and time elapses. At the same time, the rotational speed decreases. If the operation command for the inverter 2 is transmitted immediately when the first switch 3 is reconnected after the abnormality is canceled, the output of the inverter 2 and the rotational state of the motor M do not match, so overcurrent, overvoltage, etc. An abnormal condition occurs.

  Therefore, after the first switch 3 is connected, after waiting for the operation start delay time T2 until the rotational speed of the motor M becomes less than a predetermined value (for example, less than 100 to 200 rpm), an operation command for the inverter 2 is transmitted. As a result, it is possible to prevent the occurrence of abnormal conditions such as overcurrent and overvoltage.

(E)
Although the motor drive system 1 according to the first embodiment includes the switching unit 7 for power supply switching, the present invention is not limited to this. As a modification of the first embodiment, as shown in FIG. 6, the motor drive system 1 directly connects an engine generator EP different from the commercial power supply AP to the motor, separately from the path between the commercial power supply AP and the motor. It is only necessary to include the direct line 5 to be opened and the second switch 6 to open and close the direct line 5. In this case as well, even when the commercial power supply AP cannot be used, the motor M can be driven using AC power supplied from the engine generator EP.

[Second Embodiment]
In the motor drive system 1 according to the first embodiment, after the control unit 4 performs the shut-off operation of the first switch 3, the stop operation of the inverter 3, the connection operation of the first switch 3, and the predetermined switch Although the operation start operation of the inverter 2 is performed after the operation start delay time T2 has elapsed, the present invention is not limited to this.

  As a second embodiment, the control unit 4 may perform a reset operation instead of the breaking operation of the first switch 3 before the stop operation of the inverter 3.

  The configuration of the motor drive system 1 according to the second embodiment is the same as the main configuration of the motor drive system 1 according to the first embodiment shown in FIGS. 1 and 2, but the control unit 4 is as follows. It differs in that it works.

  That is, in the motor drive system 1 in the second embodiment, the control unit 4 first performs a reset operation to reset the motor drive system 1 to the initial state after the commercial power source AP is turned on or off and then turned on again. To do. Thereafter, the control unit 4 performs a stop operation for stopping the inverter 2, then performs a connection operation for connecting the first switch 3, and then, after the elapse of a predetermined operation start delay time T <b> 2, the inverter 2. The operation start operation is started to start the operation.

  Specifically, as shown in the flowchart shown in FIG. 7, first, after the commercial power source AP is turned on or off after being turned on as shown in step S11, the control unit is turned on as shown in step S12. 4 performs a reset operation for resetting the motor drive system 1 to return it to the initial state.

  Next, as shown in step S <b> 13, the control unit 4 transmits a stop command to the inverter 2. Thereby, since the stop time of the inverter 2 can be sufficiently secured, the motor M can be reliably restarted. In addition, it is possible to suppress the occurrence of abnormality due to the occurrence of overcurrent or overvoltage when the switch 3 is turned on again thereafter.

  Next, as shown in step S14, the control unit 4 waits for a predetermined connection delay time T1.

  Next, as shown in step S <b> 15, the control unit 4 performs a connection operation for connecting the first switch 3 thereafter. The control unit 4 connects the output of the inverter 2 by turning on the switch 3.

  Next, as shown in step S16, the control unit 4 waits for a predetermined operation start delay time T2 (see FIG. 3).

  Thereafter, as shown in step S <b> 17, the control unit 4 performs an operation start operation for starting the operation of the inverter 2. Specifically, the control unit 4 transmits an operation command to the inverter 2 to start the operation of the inverter 2.

<Features of Second Embodiment>
(1)
In the motor drive system 1 in the second embodiment, the control unit 4 first performs a reset operation for resetting the motor drive system 1 to return to the initial state after the commercial power source AP is turned on or off and then turned on again. . Thereafter, the control unit 4 performs a stop operation for stopping the inverter 2, then performs a connection operation for connecting the first switch 3, and then, after the elapse of a predetermined operation start delay time T <b> 2, the inverter 2. The operation start operation is started to start the operation.

  Therefore, the motor drive system 1 of the second embodiment can also reliably restart the motor M with a simpler configuration than the conventional one, and at the same time, prevents an abnormality when the inverter 2 and the motor M are reconnected. It becomes possible.

  In addition, this configuration makes the dependence on the inverter specification smaller than before, and increases the degree of design freedom on the control side.

(2)
Also in the motor drive system 1 according to the second embodiment, as in the first embodiment, the control unit 4 controls the connection operation to be performed after a predetermined connection delay time T1 has elapsed after the stop operation. M can be restarted more reliably, and at the same time, it is possible to more reliably prevent an abnormality when the inverter and the motor are reconnected.

(3)
In the motor drive system 1 according to the second embodiment, the connection delay time T1 is the time from when the power is turned on or when the power is turned on again to when the connection operation starts, so that the motor M can be restarted more reliably. At the same time, it is possible to more reliably prevent an abnormality when the inverter and the motor are reconnected.

(4)
Also in the motor drive system 1 according to the second embodiment, as in the first embodiment, the connection delay time is set based on the rotational speed reduction characteristic when the motor M is powered off. Rotational speed reduction time suitable for the above can be ensured. Therefore, the motor M can be restarted more reliably, and at the same time, it is possible to more reliably prevent an abnormality when the inverter and the motor are reconnected.

(5)
In the motor drive system 1 according to the second embodiment as well, as in the first embodiment, the operation start delay time T2 is the first switch after the connection start signal is input to the first switch 3 in the connection operation. 3 is set to be longer than the time until the connection of 3 is completed, so that the time until the first switch 3 is completely connected can be secured. Therefore, the motor M can be restarted more reliably, and at the same time, it is possible to more reliably prevent an abnormality when the inverter and the motor are reconnected.

(6)
As in the first embodiment, the motor drive system 1 according to the second embodiment further includes a direct line 5 that directly connects the commercial power source AP to the motor M and a second switch 6 that opens and closes the direct line 5. Therefore, the AC power of the commercial power supply AP can be directly sent to the motor M to drive the motor M.

(7)
Similarly to the first embodiment, the motor drive system 1 according to the second embodiment is further provided with a switching unit 7 for power supply switching. Therefore, the commercial power supply AP or an engine generator EP different from the commercial power supply AP is provided. The power supply to the motor M can be switched to one of them. Therefore, even when the commercial power supply AP cannot be used, it is possible to drive the motor M using AC power supplied from the engine generator EP.

(8)
The control method of the motor drive system 1 according to the second embodiment includes a reset operation for resetting the motor drive system 1 to return to the initial state after the commercial power source AP is turned on or off, and an inverter 2 Since it includes a stop operation for stopping, a connection operation for connecting the first switch 3, and an operation start operation for starting the operation of the inverter 2 after a predetermined operation start delay time T <b> 2 elapses, the configuration is simpler than before. The motor can be reliably restarted, and at the same time, it is possible to prevent an abnormality when the inverter 2 and the motor M are reconnected.

  In addition, this configuration makes the dependence on the inverter specification smaller than before, and increases the degree of design freedom on the control side.

<Modification of Second Embodiment>
(A)
As a modification of the second embodiment, as in the modification of the first embodiment, the connection delay time T1 is set to a time at which the overcurrent protection or overvoltage protection of the inverter 2 does not work when the motor M is restarted. May be. Also in this case, the motor M can be restarted more reliably, and at the same time, an abnormality at the time of reconnection between the inverter and the motor can be more reliably prevented.

(B)
Further, since there is a delay from power-on or power-on to reset operation, as another modification of the second embodiment, the connection delay time T1 is from the reset operation to the start of the connection operation. It may be time. Also in this case, the motor M can be restarted more reliably, and at the same time, an abnormality at the time of reconnection between the inverter and the motor can be more reliably prevented.

  INDUSTRIAL APPLICABILITY The present invention can be widely used in the fields of a motor drive system that controls an inverter with an inverter and a control method thereof.

DESCRIPTION OF SYMBOLS 1 Motor drive system 2 Inverter 3 1st opening / closing part 4 Control part 5 Direct connection line 6 2nd opening / closing part 7 Switching part 8 Branch line

Patent No. 2793843 Japanese Patent No. 3123220

Claims (13)

An inverter (2) for driving the motor;
A first switch (3) connected between the output side of the inverter (2) and the motor;
A control unit (4) for controlling the inverter (2) and the first switch (3);
A motor drive system (1) comprising:
The control unit (4) shuts off the output of the inverter (2) by the first switch (3) when the commercial power supply (AP) or the motor drive system (1) is in an abnormal state. After that, a stop operation for stopping the inverter (2) is performed, then a connection operation for connecting the first switch (3) is performed, and then a predetermined operation start delay time elapses. A motor drive system (1) characterized in that an operation start operation for starting the operation of the inverter (2) is performed later.   The system (1) according to claim 1, wherein the control unit (4) controls the connection operation to be performed after a predetermined connection delay time has elapsed after the stop operation.   The system (1) according to claim 2, wherein the connection delay time is a time from the end of the abnormal state to the start of operation of the connection operation.   The system (1) according to claim 2, wherein the connection delay time is a time from the start of the abnormal state to the start of the connection operation.   The system (1) according to claim 2, wherein the connection delay time is a time from when the first switch (3) is cut off to when the connection operation starts.   The system (1) according to any one of claims 2 to 5, wherein the connection delay time is set based on a rotation speed reduction characteristic when the motor is powered off.   The system (1) according to any one of claims 2 to 5, wherein the connection delay time is set to a time at which overcurrent protection or overvoltage protection of the inverter (2) does not work when the motor is restarted.   The operation start delay time is longer than the time from when a connection start signal is input to the first switch (3) in the connection operation until the connection of the first switch (3) is completed. System (1) according to claim 1, set. A rotation number measuring means for measuring the rotation number of the motor;
The system (1) according to claim 1, wherein the operation start delay time is a time until the rotational speed of the motor becomes less than a predetermined value after the connection of the first switch (3). A direct line (5) for directly connecting the commercial power source (AP) to the motor;
The system (1) according to any one of claims 1 to 9, further comprising a second switch (6) for opening and closing the direct line (5). A switching unit (7) for switching power supply to the motor to either the commercial power source (AP) or a generator (EP) different from the commercial power source (AP).
The system (1) according to any of claims 1 to 10, further comprising: A direct line (5) for directly connecting a generator (EP) different from the commercial power source (AP) to the motor;
The system (1) according to any one of claims 1 to 9, further comprising a second switch (6) for opening and closing the direct line (5). An inverter (2) for driving the motor;
The first switch (3) connected to the output side of the inverter (2);
A method for controlling a motor drive system (1) comprising:
A shut-off operation for shutting off the output of the inverter (2) by the first switch (3) when the commercial power supply (AP) or the motor drive system (1) is in an abnormal state;
A stop operation for stopping the inverter (2);
A connecting operation for connecting the first switch (3);
A method for controlling the motor drive system (1), comprising: an operation start operation for starting the operation of the inverter (2) after a lapse of a predetermined operation start delay time.

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