JP2020167914A - Electric motor system - Google Patents

Abstract

An object of the present invention is to provide an electric motor system that can reduce the load on equipment by keeping the starting current low, and that can be replaced in a short period of time when the electric motor breaks down. A drive source (4) for operating a load device (2) with electric power from a power source (3) includes a first induction motor (6), a second induction motor (7), outputs of the first induction motor (6) and outputs of the second induction motor (7). The control unit 5 controls the drive source 4 up to the rated operation required for the load device 2 to perform a predetermined function. The starting control includes a first induction motor operation control for operating the first induction motor 6 and a second induction motor operation control for operating the second induction motor 7, and the first induction motor operation control is started, the second induction motor operation control is started. [Selection drawing] Fig. 3

Description

The present invention relates to an electric motor system suitable as a drive source for disaster prevention equipment and the like.

Generally, disaster prevention equipment such as a fire extinguishing pump and a smoke exhaust fan is connected to one electric motor and a generator as a power source for each equipment.
By the way, when the induction motor is moved by direct insertion, a current of about 600% of the rated current flows at the time of starting as shown by the solid line in FIG. 1 (a) when the output is 160 kW, and FIG. 1 (b) As shown by the solid line, the starting torque is about 200% of the rated torque.
In the figure, the rotation speed of 1500 times / min is the theoretical rated value of the synchronous motor, and in the case of the induction motor, slippage occurs by 2 to 3% of the synchronous rotation speed, and actually 1500 times / min. Rated operation is performed without reaching. Further, the torque squared reduction load characteristic Tr, which is a reference characteristic, is calculated from the torque characteristic when the motor is directly inserted into the motor, and the current squared reduction load characteristic Ec at that time is calculated.

By the way, the capacity of the generator is selected according to the strength of the starting current, so if the starting current is too strong compared to the rated current, it is necessary to use a generator with a larger capacity than necessary, and the installation space Not only will the cost increase, but equipment costs and running costs will be high.
Therefore, when such a large output induction motor is used, a reduced voltage starting method such as a star delta method, a reactor method, or a condorfa method is often adopted in order to keep the starting current low.

In the star delta method, the operation is started with the stator winding as the star connection, and as shown in FIGS. 2 (a) and 2 (b), when the current characteristics or torque characteristics intersect with the squared reduction load characteristics Ec and Tr. Switch to delta connection with.
In this star delta method, the circuit is simple and inexpensive, and when the rated current is 100%, the starting current is only about 200% (about 1/3 of the direct insertion), and the reduction rate of the starting torque is the rated torque. It is about 66% of. However, there is a drawback that the rate of change of current and torque is large when switching from star to delta.
In addition, the reactor method and the condorfa method require an expensive switching device at the time of starting, so that the cost is very high.

The applicant first provided two rotors on one rotating shaft in one casing, provided each rotor with a stator facing each other, operated one rotor, and then installed the other rotor. A twin stator electric motor to be operated was proposed (see Patent Document 1).
According to this twin stator motor, the starting current can be lowered by a simple structure, the generator capacity can be suppressed, and the shock at the time of starting switching can be small.

Japanese Patent No. 2003560

Disaster prevention equipment such as fire extinguishing pumps and smoke exhaust fans installed in facilities such as high-rise buildings and large underground structures require high-power electric motors, but electric motors exceeding 90 kW are usually used. It is a made-to-order product, and in the event of a failure, it often takes a long period of three months or more to deliver a new electric motor. If the disaster prevention equipment cannot be used, the facilities equipped with it may be off limits for safety reasons, and in particular, in the case of a customer attraction facility, enormous damage may occur.

Although the twin stator motor as described in Patent Document 1 can suppress the starting current, it still requires an output according to the load device, so that it fails when connected to a large load device. It was not possible to eliminate the drawback of not being able to deliver immediately in an emergency such as.
An object of the present invention to be solved is to provide an electric motor system which can suppress the starting current to a low level to reduce the load on the equipment and can be replaced in a short period of time when the electric motor is damaged. ..

The invention according to claim 1 of the present application is an electric motor system including a load device, a power source, a control unit, a drive source for operating the load device by power from the power source, and a control unit for controlling the drive source. The load device has one input shaft for exerting its function, and the drive sources are a first induction motor, a second induction motor, an output of the first induction motor, and the above. The control unit has an interlocking unit capable of operating the input shaft in combination with the output of the second induction motor, and the control unit drives the load device to the rated operation required for performing a predetermined function. The start control for controlling the source is performed, and the start control includes a first induction motor operation control for operating the first induction motor and a second induction motor operation control for operating the second induction motor. After starting the first induction motor operation control, the unit starts the second induction motor operation control, and when the second induction motor operation control is started, the first induction motor operation control is performed. It is an electric motor system characterized by performing start control.

According to the second aspect of the present application, the first induction motor operation control includes a first induction motor reduced voltage operation control for operating the first induction motor at a reduced voltage and an operation for operating the first induction motor at a normal voltage. The first induction motor normal operation control and the control for switching from the first induction motor devoltage operation control to the first induction motor normal operation control are included, and the second induction motor operation control includes. The second induction motor normal operation control for operating the second induction motor at a normal voltage is included, and the control unit switches from the first induction motor devoltage operation control to the operation from the first induction motor normal voltage control. The electric motor system according to claim 1, wherein the second induction motor normal operation control is performed after the control is performed.

In the invention according to claim 3 of the present application, the second induction motor operation control includes a second induction motor reduced voltage operation control for operating the second induction motor at a reduced voltage, and the control unit is the first. The electric motor system according to claim 2, wherein the second induction motor reduced voltage operation control is performed before the control for switching from the induction motor reduced voltage operation control to the first induction motor normal operation control is performed. Is.

The invention according to claim 4 of the present application is an electric motor system including a load device, a power source, a drive source for operating the load device by electric power from the power source, and a control unit for controlling the drive source. The load device has one input shaft for exerting its function, and the drive sources are a first induction motor, a second induction motor, an output of the first induction motor, and the second induction motor. The first induction motor has an interlocking portion capable of operating the input shaft in combination with the output of the first induction motor, and the first induction motor is provided on the same output shaft and the stators provided on the same output shaft face each other. An induction motor including two rotors, the control unit performs start control to control the drive source up to the rated operation required for the load device to perform a predetermined function, and the start control is performed. , The first induction motor operation control for operating the first induction motor and the second induction motor operation control for operating the second induction motor are included, and the first induction motor operation control reduces the first rotor. The first rotor reduced voltage operation control for operating at a voltage, the first rotor normal operation control for operating the first rotor at a normal voltage, and the operation from the first rotor reduced voltage operation control to the first rotor normal operation control. From the control to switch to, the second rotor reduced voltage operation control for operating the second rotor at a reduced voltage, the second rotor normal operation control for operating the second rotor at a normal voltage, and the second rotor reduced voltage operation control. The control for switching to the operation to the second rotor normal operation control is included, and the control unit starts the second induction motor operation control after starting the first induction motor operation control, and then starts the second induction motor operation control. The electric motor system is characterized in that when the electric motor operation control is started, the start control that performs the first induction motor operation control is performed.

The invention according to claim 5 of the present application includes the second induction motor normal operation control for operating the second induction motor at a normal voltage in the second induction motor operation control, and the control unit reduces the first rotor. After switching from the voltage operation control to the first rotor normal operation control, when the first rotor normal operation control and the second rotor normal operation control are performed, the second induction motor normal operation control The electric motor system according to claim 4, wherein the motor system is characterized in that.

The invention according to claim 6 of the present application is characterized in that the control unit performs the second rotor reduced voltage operation control before switching from the first rotor reduced voltage operation control to the first rotor normal operation control. The electric motor system according to claim 5.

The invention according to claim 7 of the present application is an electric motor system including a load device, a power source, a drive source for operating the load device by electric power from the power source, and a control unit for controlling the drive source. The load device has one input shaft for exerting its function, and the drive sources are a first induction motor, a second induction motor, an output of the first induction motor, and the second induction motor. The first induction motor has an interlocking portion capable of operating the input shaft in combination with the output of the first induction motor, and the first induction motor is provided on the same output shaft and the stators provided on the same output shaft face each other. An induction motor including two rotors, the second induction motor is an induction motor provided with a third rotor and a fourth rotor provided on the same output shaft and facing each other with stators provided on the same output shaft. The control unit controls the drive source to control the drive source up to the rated operation required for the load device to perform a predetermined function. In the start control, the first induction motor is operated. Induction motor operation control and second induction motor operation control for operating the second induction motor are included, and the first induction motor operation control includes a first rotor reduced voltage operation for operating the first rotor at a reduced voltage. Control, first rotor normal operation control for operating the first rotor at a normal voltage, control for switching from the first rotor devoltage operation control to the first rotor normal operation control, and the second rotor. The second rotor reduced voltage operation control for operating at a reduced voltage, the second rotor normal operation control for operating the second rotor at a normal voltage, and the second rotor reduced voltage operation control to the first rotor normal operation control. Control to switch to operation is included, and the second induction motor operation control includes a third rotor normal operation control for operating the third rotor at a normal voltage and a fourth rotor for operating the fourth rotor at a normal voltage. The normal operation control is included, and when the control unit starts the second induction motor operation control after starting the first induction motor operation control, and starts the second induction motor operation control, the control unit starts the second induction motor operation control. It is an electric motor system characterized by performing start control which performs the first induction motor operation control.

In the invention according to claim 8 of the present application, the first induction motor operation control includes a control for switching from the first rotor reduced voltage operation control to the first rotor normal operation control, and the control unit is the first. After switching from the rotor reduced voltage operation control to the first rotor normal operation control, when the first rotor normal operation control and the second rotor normal operation control are performed, the third rotor normal operation It is characterized in that the fourth rotor normal operation control is performed when the control is performed and then the first rotor normal operation control, the second rotor normal operation control, and the third rotor normal operation control are performed. The electric motor system according to claim 7.

The invention according to claim 9 of the present application is characterized in that the control unit performs the second rotor reduced voltage operation control before switching from the first rotor reduced voltage operation control to the first rotor normal operation control. The electric motor system according to claim 8.

The invention according to claim 10 of the present application comprises claims 1 to 9, wherein the power source is a generator, and the load device is a disaster prevention device such as a fire extinguishing pump, a smoke exhaust fan, and a drainage pump. The electric motor system according to any one of the items.

The electric motor system according to any one of claims 1 to 10, wherein the invention according to claim 11 of the present application is characterized in that the rated output of the first induction motor is smaller than the rated output of the second induction motor. Is.

According to a twelfth aspect of the present application, the drive source further has at least a third induction motor, and the interlocking portion further operates the input shaft in combination with at least the output of the third induction motor. The start control further includes a third induction motor operation control for operating the third induction motor, and the control unit starts the second induction motor operation control, and then the second induction motor operation control is started. (Iii) The electric motor system according to any one of claims 1 to 11, wherein the induction motor operation control is started and the start control is performed.

According to the present invention, since one load device is operated by two induction motors, the output of each induction motor is about the same as that of a general-purpose electric motor that is always in stock even when a large load device is used. Since it is small, it can be recovered in a short period of time even if a motor failure occurs, and economic and time loss can be suppressed.
By combining the outputs of the two induction motors, the optimum output required to operate the load equipment can be obtained, and there is no waste of electric power.
Since the second induction motor is operated after the first induction motor is operated, the starting current is suppressed to be smaller than that of operating one motor having a large output, and as a result, the power supply capacity can be reduced and the equipment can be reduced. The burden is reduced.

In addition, when the first induction motor is operated, if it is operated at a reduced voltage and then at a normal voltage, the starting current can be further reduced.

In addition, when operating the second induction motor, if it is operated at a reduced voltage and then at a normal voltage, the current change rate at the start of the operation of the second induction motor can be small.

In addition, as at least the first induction motor, an induction motor having a first rotor and a second rotor provided on the same output shaft and a stator facing each of these rotors is used, and the voltage of the first rotor is reduced. If the second rotor is operated at a reduced voltage and then at a normal voltage after the operation at the normal voltage, the starting current can be further reduced and the change in the current becomes smooth.

In addition, if the rated output of the first induction motor is made smaller than the rated output of the second induction motor, the starting current can be made smaller.

In addition, since one load device is operated by at least three induction motors, the output of each induction motor is higher than that of a general-purpose motor that is always in stock, even when a large load device is used. Since it is small, even if a motor failure occurs, it can be recovered in a short period of time, and economic and time loss can be suppressed. Further, by combining the outputs of three or more induction motors, the optimum output required for operating the load device can be obtained and there is no waste of electric power.

It is a figure which shows the starting characteristic of the directly inserted electric motor, (a) shows the starting current characteristic, (b) shows the starting torque characteristic. It is a figure which shows the starting characteristic of the electric motor started by the star delta method, (a) shows the starting current characteristic, (b) shows the starting torque characteristic. It is the schematic of the electric motor system which shows the 1st Embodiment of this invention. It is the schematic of the drive source and the load equipment which concerns on 1st Embodiment of this invention. It is a figure which shows the starting characteristic of the drive source which concerns on 1st Embodiment of this invention, (a) shows the starting current characteristic, (b) shows the starting torque characteristic. It is the schematic of the drive source and the load equipment which concerns on 2nd Embodiment of this invention. It is a figure which shows the starting characteristic of the drive source which concerns on 2nd Embodiment of this invention, (a) shows the starting current characteristic, (b) shows the starting torque characteristic. It is a figure which shows the starting characteristic of the drive source which concerns on 3rd Embodiment of this invention, (a) shows the starting current characteristic, (b) shows the starting torque characteristic. It is the schematic of the drive source and load equipment which concerns on 4th Embodiment of this invention. It is a figure which shows the starting characteristic of the drive source which concerns on 4th Embodiment of this invention, (a) shows the starting current characteristic, (b) shows the starting torque characteristic. It is the schematic of the drive source and load equipment which shows the modification 1. FIG. It is the schematic of the drive source and load equipment which show the modification 2.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. Needless to say, the present invention is not limited to the embodiments.

[First Embodiment]
Hereinafter, the first embodiment of the present invention will be described with reference to FIGS. 3 to 5.
FIG. 3 is a schematic view of an electric motor system showing a first embodiment, FIG. 4 is a schematic view of a drive source and a load device according to the first embodiment, and FIG. 5 is a schematic view of a drive according to the first embodiment. It is a figure which shows the starting current characteristic and the starting torque characteristic of a source.

In the first embodiment, as shown in FIG. 3, the electric motor system 1 controls the load device 2, the power source 3, the drive source 4 that operates the load device 2 by the electric power from the power source 3, and the drive source 4. The control unit 5 is provided.

As shown in FIG. 4, the load device 2 is a disaster prevention device such as a fire extinguishing pump, a smoke exhaust fan, and a drainage pump, and has one input shaft 2a for exerting its function.
When the load device 2 is a disaster prevention device, the power source 3 uses an emergency generator so that the load device 2 can be operated even in the event of a power failure. The generated power of the power source 3 is supplied to the drive source 4 via the control unit 5.

The drive source 4 is an interlocking unit capable of operating the input shaft 2a by combining the output of the first induction motor 6, the second induction motor 7, the output of the first induction motor 6 and the output of the second induction motor 7. Has 8.
The first induction motor 6 and the second induction motor 7 are general-purpose products having an output of 90 kW and having one rotor 60, 70 and one stator facing them in their respective casings. The reason why the output of 90 kW is set to two is that there is no standard for the output of 80 kW, and considering the output required by the load device 2, the output of one conventional induction motor is set to 160 kW. It is a setting to make it correspond. Induction motors with an output of 90 kW are more widely distributed in the market than those with an output of 160 kW, so even if a failure occurs, they are easily available and can be replaced in a short period of time.

The interlocking unit 8 is wound around the drive wheels 9 attached to the output shaft 6a of the first induction motor 6, the drive wheels 10 attached to the output shaft 7a of the second induction motor 7, and these drive wheels 9, 10. The belt 11 and the driven wheel 12 which is rotationally driven by the belt 11 and transmits the rotation to the input shaft 2a of the load device 2 are provided.

The control unit 5 performs start control that controls the drive source 4 until the rated operation required for the load device 2 to perform a predetermined function, and then controls the drive source 4 so that the load device 2 continues the rated operation. To do.
The start control includes a first induction motor operation control for operating the first induction motor 6 and a second induction motor operation control for operating the second induction motor 7. Then, the control unit 5 first starts the first induction motor operation control, then starts the second induction motor operation control, and when the second induction motor operation control is started, the first induction motor operation control It is carried out.

The first induction motor operation control includes a first induction motor reduced voltage operation control in which the first induction motor 6 is operated at a reduced voltage, and a first induction motor normal operation control in which the first induction motor 6 is operated at a normal voltage. The control for switching from the first induction motor devoltage operation control to the first induction motor normal operation control is included.
The second induction motor operation control includes a second induction motor reduced voltage operation control in which the second induction motor 7 is operated at a reduced voltage, and a second induction motor normal operation control in which the second induction motor 7 is operated at a normal voltage. The control for switching from the second induction motor reduced voltage operation control to the second induction motor normal operation control is included.

In the present embodiment, the start control of the first induction motor 6 and the second induction motor 7 employs a star delta method for switching from a star connection to a delta connection. That is, the induction motor devoltage operation control is to control the operation of the stator winding of the induction motor as a star connection, and the induction motor normal operation control is to control the operation of the stator winding of the induction motor as a delta connection. The operation control for switching from the induction motor devoltage operation control to the induction motor normal operation control is an operation control for switching the stator winding of the induction motor from the star connection to the delta connection.

The start control of the drive source 4 by the control unit 5 will be specifically described below.
The control unit 5, in which power is input from the power source 3, first performs devoltage operation control of the first induction motor with the stator winding of the first induction motor 6 as a star connection, and supplies power only to the stator of the first induction motor 6. To do. Then, the output shaft 6a and the drive wheel 9 of the first induction motor 6 rotate, and this rotational force is transmitted to the input shaft 2a via the belt 11 and the driven wheel 12.
As shown by the solid line A in FIG. 5 (a), the starting current at this time is almost equal to the current during the rated operation, and as shown in the solid line A in FIG. 5 (b), the starting torque is the torque during the rated operation. It is about 33% of.

When the first induction motor 6 is controlled by the first induction motor reduced voltage operation control, the rotation speed increases, and the torque characteristic of the solid line A intersects with the squared reduction load characteristic Tr, the control unit 5 sets the first induction motor. In addition to the reduced voltage operation control, power is also supplied to the stator of the second induction motor 7, and the second induction motor reduced voltage operation control is performed with the stator winding of the second induction motor 7 as a star connection.
Then, the output shaft 7a of the second induction motor 7 rotates, and the output of the second induction motor 7 is combined with the output of the first induction motor 6 by the interlocking unit 8 and transmitted to the input shaft 2a.
The current characteristics and torque characteristics after performing the voltage reduction operation control of the second induction motor are shown by the solid line B in FIGS. 5 (a) and 5 (b).

After that, while the first induction motor 6 is operated under the first induction motor reduced voltage operation control, the second induction motor 7 is operated under the second induction motor reduced voltage operation control, and the torque characteristic of the solid line B is the squared reduction load characteristic Tr. When the control unit 5 intersects with, the control unit 5 stops the power supply to the second induction motor 7, continues the power supply to the first induction motor 6, and switches the stator winding from the star connection to the delta connection. That is, the second induction motor devoltage operation control is stopped, and the operation is switched from the first induction motor devoltage operation control to the first induction motor normal operation control.
The current characteristics and torque characteristics after switching from the operation under the first induction motor reduced voltage operation control to the operation under the first induction motor normal operation control are shown by the solid lines C in FIGS. 5 (a) and 5 (b).

When the torque characteristic of the solid line C intersects with the squared reduction load characteristic Tr in the state where the first induction motor 6 is operated under the normal operation control of the first induction motor, the control unit 5 performs the normal operation control of the first induction motor while performing the first induction motor normal operation control. Power supply to the second induction motor 7 is started, and normal operation control of the second induction motor is performed with the stator winding of the second induction motor 7 as a delta connection.
In the operation under the normal operation control of the first induction motor of the first induction motor 6 and the operation under the normal operation control of the second induction motor of the second induction motor 7, the stator windings of both induction motors 6 and 7 are delta-connected. As shown by the solid line D in FIGS. 5 (a) and 5 (b), the current characteristics and the torque characteristics overlap with the current characteristics and the torque characteristics corresponding to one directly inserted electric motor. Then, when the rotation speed of the drive source 4 reaches the rated rotation speed, the start control is terminated and the rated operation is started.

In this way, the current and torque change gently, and the starting current is at most about twice the rated current.

[Second Embodiment]
Hereinafter, the second embodiment according to the present invention will be described together with FIGS. 6 and 7. The same parts as those in the first embodiment will be omitted, and different parts will be mainly described.

In the second embodiment, as shown in FIG. 6, the first induction motor 6 of the first embodiment is a twin stator motor having an output of 90 kW. The twin stator motor includes a first rotor 13 and a second rotor 14 provided on the same output shaft 6a, and a stator facing the first rotor 13 and the second rotor 14, respectively, in one casing. It is an induction motor. The output of 90 kW corresponds to the combined output of the first rotor 13 and the second rotor 14.
Both the stator facing the first rotor 13 and the stator facing the second rotor 14 can switch the winding from the star connection to the delta connection by the control unit 5.
The second induction motor 7 has an output of 90 kW and has substantially the same structure as the second induction motor 7 in the first embodiment, but the stator winding is fixed to the delta connection.

The start control performed by the control unit 5 includes a first induction motor operation control for operating the first induction motor 6 and a second induction motor operation control for operating the second induction motor 7. Then, the control unit 5 first starts the first induction motor operation control, then starts the second induction motor operation control, and when the second induction motor operation control is started, the first induction motor operation control It is carried out.

The first induction motor operation control includes a first rotor reduced voltage operation control in which the first rotor 13 of the first induction electric motor 6 is operated at a reduced voltage and a first rotor normal operation control in which the first rotor 13 is operated at a normal voltage. The control to switch from the first rotor reduced voltage operation control to the first rotor normal operation control, the second rotor reduced voltage operation control to operate the second rotor 14 at the reduced voltage, and the second rotor 14 to operate at the normal voltage. The second rotor normal operation control and the control for switching from the second rotor low voltage operation control to the second rotor normal operation control are included.
The second induction motor operation control includes the second induction motor normal operation control for operating the second induction motor 7 at a normal voltage.

In the present embodiment, the starting control of the first rotor 13 and the second rotor 14 of the first induction motor 6 employs a star delta method for switching from star connection to delta connection. That is, the rotor reduced voltage operation control is to control the operation of the rotor stator winding as a star connection, and the rotor normal operation control is to operate and control the rotor stator winding as a delta connection. The operation control for switching from the operation control to the rotor normal operation control is the operation control for switching the stator winding of the rotor from the star connection to the delta connection. The start control of the second induction motor 7 is a fixed method of delta connection.

The start control of the drive source 4 by the control unit 5 in the second embodiment will be specifically described below.
The control unit 5, in which power is input from the power source 3, first performs first rotor devoltage operation control with the stator winding facing the first rotor 13 of the first induction motor 6 as a star connection, and then performs the first induction motor. Power is supplied only to the stator of the first rotor 13 of 6. Then, the first rotor 13 rotates, the output shaft 6a and the drive wheel 9 of the first induction motor 6 rotate, and only the output of the output shaft 6a is input to the input shaft 2a via the interlocking unit 8.
The starting current at this time is about 50% of the rated current as shown by the solid line A in FIG. 7 (a), and the starting torque is about 50% of the rated torque as shown in the solid line A in FIG. 7 (b). It is 16%.

When the first rotor 13 of the first induction motor 6 is controlled by the first rotor reduced voltage operation control, the rotation speed increases, and the torque characteristic of the solid line A intersects with the squared reduction load characteristic Tr, the control unit 5 receives the control unit 5. In addition to the first rotor reduced voltage operation control, power is also supplied to the stator of the second rotor 14, and the second rotor reduced voltage operation control is performed with the stator winding of the second rotor 14 as a star connection.
Then, the second rotor 14 which was in the idle state is also driven and rotated, and the rotation speed of the output shaft 6a of the first induction motor 6 is increased.
The current characteristics and torque characteristics after performing the second rotor devoltage operation control are shown by the solid line B in FIGS. 7 (a) and 7 (b).

After that, while the first rotor 13 of the first induction motor 6 is operated under the first rotor reduced voltage operation control, the second rotor 14 is operated under the second rotor reduced voltage operation control, and the torque characteristic of the solid line B is the square reduction load. When intersecting with the characteristic Tr, the control unit 5 stops the power supply to the stator of the second rotor 14, continues the power supply to the stator of the first rotor 13, and switches the stator winding from the star connection to the delta connection. That is, the second rotor devoltage operation control is stopped, and the operation is switched from the first rotor devoltage operation control to the first rotor normal operation control.
The current characteristics and torque characteristics when only the first rotor 13 is controlled for normal operation are shown by solid lines C in FIGS. 7 (a) and 7 (b).

When only the first rotor 13 of the first induction motor 6 is operated under the first rotor normal operation control and the torque characteristic of the solid line C intersects with the squared reduction load characteristic Tr, the control unit 5 controls the first rotor normal operation. The power supply is started by using the stator winding of the second rotor 14 as a delta connection, and the second rotor 14 is operated under the normal operation control of the second rotor. In this state, the first induction motor 6 is normally operated when the first rotor 13 is operated under the normal operation control of the first rotor and the second rotor 14 is operated under the normal operation control of the second rotor.
The current characteristics and torque characteristics when only the first induction motor 6 is normally operated and the second induction motor 7 is stopped are shown by solid lines D in FIGS. 7 (a) and 7 (b).

In a state where only the first induction motor 6 is normally operated, if the torque characteristic of the solid line D intersects with the squared reduction load characteristic Tr, the control unit 5 is in a state where only the first induction motor 6 is normally operated (the first). (One induction motor normal operation control state), power supply to the second induction motor 7 in which the stator windings are delta-connected is started, and the second induction motor normal operation control is performed.
Then, both the first induction motor 6 and the second induction motor 7 are normally operated, and the output of the first induction motor 6 and the output of the second induction motor 7 are combined by the interlocking unit 8 and input to the input shaft 2a. ..
The current characteristics and torque characteristics of the first induction motor 6 and the second induction motor 7 during normal operation are as shown in the solid line E of FIGS. 7 (a) and 7 (b). It overlaps with the current characteristics and torque characteristics corresponding to the group. Then, when the rotation speed of the drive source 4 reaches the rated rotation speed, the start control is terminated and the rated operation is started.

In the second embodiment, switching is performed in multiple stages as compared with the first embodiment, so that the changes in current and torque become more gentle.

[Third Embodiment]
Hereinafter, a third embodiment according to the present invention will be described with reference to FIG. The same parts as those in the first and second embodiments will be omitted, and different parts will be mainly described.
In the third embodiment, the stator winding of the second induction motor 7 can be switched from the star connection to the delta connection, and for the second induction motor operation control, the second induction motor 7 is operated at a reduced voltage. Induction motor devoltage operation control, second induction motor normal operation control that operates the second induction motor 7 at normal voltage, and control that switches from operation from second induction motor devoltage operation control to second induction motor normal operation control. It differs from the second embodiment in that and is included.

Hereinafter, the start control of the drive source 4 by the control unit 5 in the third embodiment will be specifically described.
The control unit 5 to which the power is input from the power source 3 performs the first rotor devoltage operation control and operates only the first rotor 13 of the first induction motor 6.
The starting current at this time is about 50% of the rated current as shown by the solid line A in FIG. 8 (a), and the starting torque is about 50% of the rated torque as shown in the solid line A in FIG. 8 (b). It is 16%.

When the torque characteristic of the solid line A intersects with the squared reduction load characteristic Tr in a state where only the first rotor 13 of the first induction motor 6 is operated by performing the first rotor devoltage operation control, the control unit 5 is set to the first. In addition to the one-rotor low-voltage operation control, the second rotor low-voltage operation control is also performed.
The current characteristics and torque characteristics after performing the second rotor devoltage operation control are shown by the solid line B in FIGS. 8 (a) and 8 (b).

After that, while the first rotor 13 of the first induction motor 6 is operated under the first rotor reduced voltage operation control, the second rotor 14 is operated under the second rotor reduced voltage operation control, and the torque characteristic of the solid line B is the square reduction load. When intersecting with the characteristic Tr, the control unit 5 stops the second rotor devoltage operation control and controls to switch from the first rotor devoltage operation control to the first rotor normal operation control.
The current characteristics and torque characteristics when only the first rotor 13 is controlled for normal operation are shown by solid lines C in FIGS. 8 (a) and 8 (b).

In a state where only the first rotor 13 of the first induction motor 6 is operated under the first rotor normal operation control, if the torque characteristic of the solid line C then intersects with the squared reduction load characteristic Tr, the control unit 5 moves to the first rotor normal operation. While performing the operation control, the second rotor 14 is operated under the second rotor normal operation control, and the first induction motor 6 is controlled to be in the normal operation.
The current characteristics and torque characteristics when only the first induction motor 6 is normally operated and the second induction motor 7 is stopped are shown by solid lines D in FIGS. 8 (a) and 8 (b).

In a state where only the first induction motor 6 is normally operated, if the torque characteristic of the solid line D intersects with the squared reduction load characteristic Tr, the control unit 5 is in a state where only the first induction motor 6 is normally operated (the first). While the one-induction motor is in the normal operation control state), the power supply to the second induction motor 7 having the stator winding as a star connection is started, and the second induction motor devoltage operation control is performed.
When the first induction motor 6 is normally operated and the second induction motor 7 is operated at a reduced voltage in this way, the output of the first induction motor 6 and the output of the second induction motor 7 are combined and input by the interlocking unit 8. It is output to the shaft 2a.
The current characteristics and torque characteristics when the first induction motor 6 is normally operated and the second induction motor 7 is operated at a reduced voltage are shown by solid lines E in FIGS. 8 (a) and 8 (b).

If the torque characteristic of the solid line E intersects with the squared reduction load characteristic Tr when the first induction motor 6 is normally operated and the second induction motor 7 is in the reduced voltage operation, the control unit 5 will perform the first induction motor 6 Is in the normal operation state (first inductive motor normal operation control state), and the stator winding of the second inductive motor 7 is switched from the star connection to the delta connection. Control to switch to normal operation control operation.
Then, both the first induction motor 6 and the second induction motor 7 are normally operated, and the output of the first induction motor 6 and the output of the second induction motor 7 are combined by the interlocking unit 8 and input to the input shaft 2a. ..
The current characteristics and torque characteristics of the first induction motor 6 and the second induction motor 7 during normal operation are as shown in the solid line F of FIGS. 8 (a) and 8 (b). It overlaps with the current characteristics and torque characteristics corresponding to the group. Then, when the rotation speed of the drive source 4 reaches the rated rotation speed, the start control is terminated and the rated operation is started.

In the third embodiment, since the number of switchings is further increased, the changes in current and torque become gentler, and the maximum current during acceleration is suppressed to about 150% of the rated current.

[Fourth Embodiment]
Hereinafter, a fourth embodiment according to the present invention will be described together with FIGS. 9 and 10. The same parts as those in the first to third embodiments will be omitted, and different parts will be mainly described.

In the fourth embodiment, as shown in FIG. 9, the second induction motor 7 of the second embodiment is a twin stator motor having an output of 90 kW. The second induction motor 7 is provided on the same output shaft 7a in one casing, and includes a third rotor 15 and a fourth rotor 16 on which the stators provided in each face each other. Further, the stator facing the third rotor 15 and the stator winding facing the fourth rotor 16 are fixed to the delta connection.
The second induction motor operation control by the control unit 5 includes a third rotor normal operation control in which the stator of the delta connection of the third rotor 15 is supplied to operate the third rotor at a normal voltage, and a delta connection of the fourth rotor 16. The fourth rotor normal operation control is included in which the fourth rotor is operated at a normal voltage by supplying power to the stator of the above.

Hereinafter, the start control of the drive source 4 by the control unit 5 in the fourth embodiment will be specifically described.
The control unit 5 to which the power is input from the power source 3 performs the first rotor devoltage operation control and operates only the first rotor 13 of the first induction motor 6.
The starting current at this time is about 50% of the rated current as shown by the solid line A in FIG. 10 (a), and the starting torque is about 50% of the rated torque as shown in the solid line A in FIG. 10 (b). It is 16%.

When the torque characteristic of the solid line A intersects with the squared reduction load characteristic Tr in a state where only the first rotor 13 of the first induction motor 6 is operated by performing the first rotor devoltage operation control, the control unit 5 is set to the first. In addition to the one-rotor low-voltage operation control, the second rotor low-voltage operation control is also performed.
The current characteristics and torque characteristics after performing the second rotor devoltage operation control are shown by the solid line B in FIGS. 10 (a) and 10 (b).

After that, while the first rotor 13 of the first induction motor 6 is operated under the first rotor reduced voltage operation control, the second rotor 14 is operated under the second rotor reduced voltage operation control, and the torque characteristic of the solid line B is the square reduction load. When intersecting with the characteristic Tr, the control unit 5 stops the second rotor devoltage operation control and controls to switch from the first rotor devoltage operation control to the first rotor normal operation control.
The current characteristics and torque characteristics when only the first rotor 13 is controlled for normal operation are shown by solid lines C in FIGS. 10 (a) and 10 (b).

When only the first rotor 13 of the first induction motor 6 is operated under the first rotor normal operation control and the torque characteristic of the solid line C intersects with the squared reduction load characteristic Tr, the control unit 5 controls the first rotor normal operation. The second rotor 14 is operated under the normal operation control of the second rotor, and the first induction motor 6 is controlled to be in the normal operation.
The current characteristics and torque characteristics when only the first induction motor 6 is normally operated and the second induction motor 7 is stopped are shown by solid lines D in FIGS. 10 (a) and 10 (b).

If the torque characteristic of the solid line D intersects with the squared reduction load characteristic Tr in the state where only the first induction motor 6 is normally operated, the control unit 5 is in the state where only the first induction motor 6 is normally operated (the first). (1) Induction motor normal operation control state), the third rotor normal operation control for supplying power to the stator which is the delta connection of the third rotor 15 of the second induction motor 7 is performed. No power is supplied to the stator of the fourth rotor 16 of the second induction motor 7.
When the first induction motor 6 is normally operated and only the third rotor 15 of the second induction motor 7 is normally operated in this way, the output of the first induction motor 6 and the third rotor of the second induction motor 7 are operated. The output from 15 is combined by the interlocking unit 8 and output to the input shaft 2a.
The current characteristics and torque characteristics when the first induction motor 6 is normally operated and only the third rotor 15 of the second induction motor 7 is normally operated are shown by the solid lines E in FIGS. 10 (a) and 10 (b). Shown.

Next, when the first induction motor 6 is normally operated and only the third rotor 15 of the second induction motor 7 is normally operated and the torque characteristic of the solid line E intersects with the squared reduction load characteristic Tr, the control unit 5 Is a state in which the first induction motor 6 is normally operated (first induction motor normal operation control state), and only the third rotor 15 of the second induction motor 7 is in the normal operation, while the second induction motor is in normal operation. Power is supplied to the delta-connected stator of the fourth rotor 16 of No. 7, and the fourth rotor normal voltage operation control is performed. That is, both the first induction motor 6 and the second induction motor 7 have rated connections and are normally operated.
The current characteristics and torque characteristics during normal operation of the first induction motor 6 and the second induction motor 7 are as shown by the solid line F in FIGS. 10 (a) and 10 (b). It overlaps with the current characteristics and torque characteristics corresponding to the group. Then, when the rotation speed of the drive source 4 reaches the rated rotation speed, the start control is terminated and the rated operation is started.

Also in the fourth embodiment, the changes in current and torque become gentler, and the starting current is suppressed to about 150% of the rated current.

[Modification 1]
FIG. 11 shows a modification 1 of the drive source 4.
In the first modification, the output shaft 6a of the first induction motor 6 and the output shaft 7a of the second induction motor 7 are connected in series by the first coupling 17, and the output shaft 6a of the first induction motor 6 is connected to the second cup. The ring 18 is connected to the input shaft 2a of the load device 2.
Therefore, the interlocking portion 8 including the first coupling 17 and the second coupling 18 inputs the output of the first induction motor 6 and the output of the second induction motor 7 to the input shaft 2a, and inputs the load device 2 to the input shaft 2a. Can be activated.

[Modification 2]
FIG. 12 shows a modification 2 of the drive source 4.
In the second modification, the interlocking portion 8 includes a first gear 19 attached to the output shaft 6a of the first induction motor 6, a second gear 20 attached to the output shaft 7a of the second induction motor 7, and a load device. It is composed of a third gear 21 attached to the input shaft 2a of 2.
The first gear 19 and the second gear 20 mesh with the third gear 21, and the output of the first induction motor 6 and the output of the second induction motor 7 are combined and input to the input shaft 2a.

[Other variants]
The present invention is not limited to the above embodiments. For example, the following are also included.

In the present embodiment, the load device is a disaster prevention device, but the device is not limited to this, and is a device that requires a relatively high output drive source such as a crusher and has a problem of starting repeatedly. Is also good.

In the present embodiment, the power source has been described as an advantageous generator in an emergency, but the present invention is not limited to this, and a commercial power source supplied by an electric power company can also be used. Even if a commercial power source is used, the contract fee can be reduced by reducing the capacity, and the equipment burden can be reduced.

In the present embodiment, the first induction motor and the second induction motor have the same output, but different outputs may be combined.
If the output of the first induction motor is reduced and the output of the second induction motor is increased, the starting current can be further reduced and the required output can be obtained. For example, in the first embodiment, the output of one conventional induction motor is 160 kW, and the output of two general-purpose products is 90 kW. However, the output of the first induction motor is 75 kW and the output of the second induction motor is 90 kW. Is also good. In this way, the output can be made closer to 160 kW, and an economical setting can be made.
When a large torque is required at the time of starting, the output of the first induction motor is increased and the output of the second induction motor is decreased.
Depending on the type of load equipment, the first induction motor and the second induction motor can be appropriately combined to obtain an optimum output without waste.

In the present embodiment, the control unit operates only the first induction motor or both the first induction motor and the second induction motor by switching from the reduced voltage operation control to the normal operation control. And the start control of the second induction motor may be limited to the normal operation control. Even in this way, the starting current can be suppressed to a low level and the burden on the equipment can be reduced by operating the first induction motor independently at the start of operation.

In the present embodiment, the control unit controls the drive source by the number of revolutions even at the intersection with the squared reduction load torque, but it can also be controlled by the temperature, time, and the like.
Further, although the star delta method is adopted for starting with a reduced voltage, another reduced voltage starting method may be adopted.

In the present embodiment, an example in which the control unit 5 switches the operation control of the first induction motor 6 and the second induction motor 7 according to the rotation speed at the intersection of the torque characteristic and the squared reduction load characteristic Tr has been described. And the squared reduction load characteristic Ec may be switched by the rotation speed at the intersection. Examples of this case are shown in FIGS. 5 (a), 7 (a), 8 (a), and 10 (a).

In the present embodiment, the induction motor of the drive source has been described as two units, the first induction motor and the second induction motor, but it is clarified that the present invention is not limited to this. It may be equipped with three induction motors (third induction motor) or more. In that case, all the radixes of the induction motors are combined so as to have the required rated output, and the interlocking part is also supported. Further, for the third and subsequent induction motors, the same start control as performed in the embodiment following the start control of the first induction motor and the second induction motor (for example, the third induction to the second induction motor normal operation control). (Third-induction electric motor operation control is performed by adding the second-induction electric motor operation control to the first-induction electric motor operation control, such as adding the electric motor reduced voltage operation control and then switching to the third-induction electric motor normal operation control). Go and perform start control.
As described above, it is clear that the present invention does not exclude those having three or more induction motors.
By using three or more induction motors in this way, the changes in current and torque become more gentle, and the maximum value of the starting current can be suppressed.

Each technical matter in any embodiment may be applied to other embodiments as an embodiment.

1 Electric motor system 2 Load equipment 3 Power supply 4 Drive source 5 Control unit 6 1st induction motor 7 2nd induction motor 8 Interlocking unit 9,10 Drive wheel 11 Belt 12 Trailing wheel 13 1st rotor 14 2nd rotor 15 3rd rotor 16 4th rotor 17 1st coupling 18 2nd coupling 19 1st gear 20 2nd gear 21 3rd gear 60,70 Rotor

Claims (12)

An electric motor system including a load device, a power source, a drive source for operating the load device by electric power from the power source, and a control unit for controlling the drive source.
The load device has one input shaft for exerting its function.
The drive source has an interlocking portion capable of operating the input shaft by combining the output of the first induction motor, the second induction motor, the output of the first induction motor, and the output of the second induction motor. And
The control unit performs start control that controls the drive source until the rated operation required for the load device to perform a predetermined function.
The start control includes a first induction motor operation control for operating the first induction motor and a second induction motor operation control for operating the second induction motor.
The control unit starts the second induction motor operation control after starting the first induction motor operation control, and when the second induction motor operation control is started, the first induction motor operation control is performed. An electric motor system characterized by performing the starting control that is being performed. The first induction motor operation control includes a first induction motor reduced voltage operation control for operating the first induction motor at a reduced voltage and a first induction motor normal operation control for operating the first induction motor at a normal voltage. , Control to switch from the first induction motor reduced voltage operation control to the operation to the first induction motor normal operation control, and the like.
The second induction motor operation control includes a second induction motor normal operation control for operating the second induction motor at a normal voltage.
The control unit performs the control for switching from the first induction motor reduced voltage operation control to the first induction motor normal operation control, and then performs the second induction motor normal operation control. Item 1. The electric motor system according to item 1. The second induction motor operation control includes a second induction motor reduced voltage operation control for operating the second induction motor at a reduced voltage, and a second induction motor reduced voltage operation control to the second induction motor normal operation control. Includes control to switch to driving,
The control unit is characterized in that the second induction motor reduced voltage operation control is performed before the control for switching from the first induction motor reduced voltage operation control to the first induction motor normal operation control is performed. The electric motor system according to claim 2. An electric motor system including a load device, a power source, a drive source for operating the load device by electric power from the power source, and a control unit for controlling the drive source.
The load device has one input shaft for exerting its function.
The drive source has an interlocking portion capable of operating the input shaft by combining the output of the first induction motor, the second induction motor, the output of the first induction motor, and the output of the second induction motor. And
The first induction motor is an induction motor provided with a first rotor and a second rotor provided on the same output shaft and facing each other with stators provided on the same output shaft.
The control unit performs start control that controls the drive source until the rated operation required for the load device to perform a predetermined function.
The start control includes a first induction motor operation control for operating the first induction motor and a second induction motor operation control for operating the second induction motor.
The first induction motor operation control includes a first rotor reduced voltage operation control in which the first rotor is operated at a reduced voltage, a first rotor normal operation control in which the first rotor is operated at a normal voltage, and the first. Control to switch from rotor reduced voltage operation control to operation to the first rotor normal operation control, second rotor reduced voltage operation control to operate the second rotor at reduced voltage, and operation of the second rotor at normal voltage. The second rotor normal operation control and the control for switching from the second rotor low voltage operation control to the operation to the second rotor normal operation control are included.
The control unit starts the second induction motor operation control after starting the first induction motor operation control, and when the second induction motor operation control is started, the first induction motor operation control is performed. An electric motor system characterized by performing the starting control that is being performed. The second induction motor operation control includes a second induction motor normal operation control for operating the second induction motor at a normal voltage.
When the control unit performs the first rotor normal operation control and the second rotor normal operation control after switching from the first rotor low voltage operation control to the first rotor normal operation control. The electric motor system according to claim 4, wherein the second induction motor normal operation control is performed. The electric motor system according to claim 5, wherein the control unit performs the second rotor devoltage operation control before switching from the first rotor devoltage operation control to the first rotor normal operation control. An electric motor system including a load device, a power source, a drive source for operating the load device by electric power from the power source, and a control unit for controlling the drive source.
The load device has one input shaft for exerting its function.
The drive source has an interlocking portion capable of operating the input shaft by combining the output of the first induction motor, the second induction motor, the output of the first induction motor, and the output of the second induction motor. And
The first induction motor is an induction motor provided with a first rotor and a second rotor provided on the same output shaft and facing each other with stators provided on the same output shaft.
The second induction motor is an induction motor provided with a third rotor and a fourth rotor provided on the same output shaft and facing each other with stators provided on the same output shaft.
The control unit performs start control that controls the drive source until the rated operation required for the load device to perform a predetermined function.
The start control includes a first induction motor operation control for operating the first induction motor and a second induction motor operation control for operating the second induction motor.
The first induction motor operation control includes a first rotor reduced voltage operation control in which the first rotor is operated at a reduced voltage, a first rotor normal operation control in which the first rotor is operated at a normal voltage, and the first. Control to switch from rotor reduced voltage operation control to operation to the first rotor normal operation control, second rotor reduced voltage operation control to operate the second rotor at reduced voltage, and operation of the second rotor at normal voltage. The second rotor normal operation control and the control for switching from the second rotor low voltage operation control to the first rotor normal operation control are included.
The second induction motor operation control includes a third rotor normal operation control for operating the third rotor at a normal voltage and a fourth rotor normal operation control for operating the fourth rotor at a normal voltage.
The control unit starts the second induction motor operation control after starting the first induction motor operation control, and when the second induction motor operation control is started, the first induction motor operation control is performed. An electric motor system characterized by performing the starting control that is being performed. When the control unit performs the first rotor normal operation control and the second rotor normal operation control after switching from the first rotor low voltage operation control to the first rotor normal operation control. When the third rotor normal operation control is performed, and then the first rotor normal operation control, the second rotor normal operation control, and the third rotor normal operation control are performed, the fourth rotor normal operation control is performed. The electric motor system according to claim 7, wherein the operation is controlled. The electric motor system according to claim 8, wherein the control unit performs the second rotor devoltage operation control before switching from the first rotor devoltage operation control to the first rotor normal operation control. The power source is a generator
The electric motor system according to any one of claims 1 to 9, wherein the load device is a disaster prevention device such as a fire extinguishing pump, a smoke exhaust fan, and a drainage pump. The electric motor system according to any one of claims 1 to 10, wherein the rated output of the first inductive motor is smaller than the rated output of the second inductive motor. The drive source further comprises at least a third induction motor.
The interlocking portion can further operate the input shaft by at least matching the output of the third induction motor.
The start control further includes a third induction motor operation control for operating the third induction motor.
The invention according to any one of claims 1 to 11, wherein the control unit starts the second induction motor operation control and then starts the third induction motor operation control to perform the start control. Electric motor system.