JPH07131990A - Start controller for multiple motors - Google Patents

Abstract

PURPOSE:To control the starting of multiple three-phase induction motors by connecting a starting circuit switching means and a voltage controlling means in series between a motor and an AC power source, connecting an operating circuit switching means in series, and starting motors in order after that with the starting circuit switching means being in an nonoperating condition. CONSTITUTION:Starting electromagnetic relays FM1-FMn are connected in series between a three-phase power source and induction motors M1-Mn along with an SCR driving part 1, in a constant period of time at the time of starting by the control of a sequence controller 3. In other words, in the constant period of time at the time of starting, three-phase voltage waveform-controlled by the SCR driving part 1 is applied to the induction motors M1-Mn through these starting electromagnetic relays FM1-FMn. Operating electromagnetic relays BM1-BM1 connect the induction induction motors M1-Mn to the three-phase power source directly after a starting period by the control of the sequence controller 3. Accordingly, it becomes possible to perform the start control of multiple three-phase induction motors with a simple structure and protect them from having starting overcurrent.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a starting control device for an electric motor, and more particularly to a device for starting a plurality of three-phase induction motors in time series.

[0002]

2. Description of the Related Art Conventionally, as a typical method for starting a three-phase induction motor, a Y-.DELTA. Starting method or a reactor method used in a range of several tens of horsepower or more utilizing the principle of an autotransformer, etc. It has been known. These conventional starting methods are
The starting current is suppressed by reducing the voltage applied to each phase of the electric motor at the time of starting to an appropriate level. By the way, in such a starting method, since a mechanical contact such as an electromagnetic relay is used to switch the circuit connection at the time of starting and the subsequent operation at the rated voltage, a relatively large current is generated. It will be mechanically interrupted, and an arc will be generated at the contact point, so the contact will be considerably worn. Also, when switching the circuit connection state,
Since the magnitude of the electric current changes abruptly, the influence also affects the power source and the electric motor and causes the power source and the electric motor to deteriorate, which causes a problem that the maintenance and repair cost of the equipment increases.

[0003]

For this reason, the Applicant has proposed that 3
We proposed a starting device that suppresses an overcurrent at the time of starting the phase induction motor and shifts the three-phase induction motor to the rated voltage operation (Japanese Patent Application No. 4-170007). However,
This starting device starts one three-phase induction motor, and does not consider any case of starting a plurality of three-phase induction motors.

However, in reality, there are many situations in which a plurality of three-phase induction motors are used at the same time. If the above-mentioned starting devices are used for the number of induction motors used, not only the cost will increase, but also a plurality of When three-phase induction motors are started at the same time, currents that are two to three times the rated currents respectively flow in at the time of starting, so during this time flicker phenomenon occurs and the power supply voltage drops, and the operating efficiency of the motor decreases. There was a problem. Therefore, there has been a demand for a start control device capable of safely and reliably shifting to rated voltage operation while protecting a plurality of three-phase induction motors from an overcurrent at the time of starting without using a plurality of start devices.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a starting control device capable of controlling the starting of a large number of three-phase induction motors with a simple structure. Another object of the present invention is to provide a starting control device that reliably protects an electric motor from an overcurrent at the time of starting, consumes less reactive power as much as possible, and has good operating efficiency.

[0006]

A multiple starting device for an electric motor according to the present invention is provided corresponding to the number of electric motors and voltage control means for controlling the voltage applied to the electric motors according to the rotating state of the electric motors. A plurality of starting circuit opening / closing means connected in series with the voltage control means, a plurality of operating circuit opening / closing means provided corresponding to the number of electric motors and connecting between the electric motors and the power sources, and the plurality of starting circuit opening / closing means. Circuit opening and closing means and operation control means for controlling the operation of the operation circuit opening and closing means, wherein the operation control means operates one starting circuit opening and closing means among the plurality of starting circuit opening and closing means. And 1
This starting circuit opening / closing means and the voltage control means are connected in series between the electric motor and the AC power source, and after a certain period of time,
Of the plurality of operating circuit opening / closing means, one operating circuit opening / closing means is in an operating state, and the operating circuit opening / closing means is connected in series between an AC power source and the one electric motor, and then, By sequentially repeating the control operation to bring one starting circuit opening / closing means into the non-operating state,
A plurality of electric motors are sequentially started.

[0007]

At the time of starting, the operation control means connects the starting circuit opening / closing means and the voltage control means in series between the AC power supply and one electric motor. Therefore, since a voltage whose waveform is controlled by the voltage control means is applied to the electric motor, so-called soft start is possible. Then, after a lapse of a certain time, the operation circuit opening / closing means is connected between the electric motor and the AC power source in a state where the starting circuit opening / closing means and the voltage control means are connected to the electric motor. . Therefore, the operation circuit opening / closing means is connected in parallel with the starting circuit opening / closing means and the voltage control means, the motor is switched to the rated voltage operation in a stable state, and after a certain period of time elapses, the starting circuit is opened. Since the opening / closing means is deactivated by the operation controlling means, the electric motor is supplied with power only through the operating circuit opening / closing means, and the start of one unit is completed. Then, the operation control means starts the next electric motor to be started in exactly the same manner.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A multi-start control system for a three-phase induction motor according to the present invention will be described below with reference to FIGS. Here, FIG. 1 is a configuration diagram showing a circuit configuration example in one embodiment of a multi-phase induction motor multi-start control apparatus according to the present invention, and FIG. 2 is a multi-phase induction motor multi-start control apparatus shown in FIG. FIG. 3 is a circuit diagram showing a concrete circuit example of a sequence controller used in FIG. 3, FIG. 3 is a timing diagram of main parts for explaining the operation of the apparatus of the embodiment shown in FIG. 1, and FIG. FIG. 5 is a circuit diagram showing an example of a specific circuit of the starting unit used in the starting control device, and FIG. 5 is a timing chart in a main part for explaining the operation of the starting unit shown in FIG.

This multi-start control device for a three-phase induction motor controls the operation of the SCR drive unit 1 and the SCR drive unit 1 as voltage control means for controlling the applied voltage of the induction motor, and controls the operation of the SCR drive unit 1.
A starter 2 which constitutes a voltage control means together with the CR driver 1.
Starting electromagnetic relay FM1 as starting circuit opening / closing means
FMn, operating electromagnetic relays BM1 to BMn as operating circuit opening / closing means, and starting electromagnetic relays FM1 to FM
n and the sequence controller 3 as an operation control means for controlling the operations of the electromagnetic solenoids for operation BM1 to BMn are the main constituent elements, and the plurality of three-phase induction motors M1 to M1.
The Mn is sequentially started. The starting unit 2 includes three-phase induction motors (hereinafter referred to as "induction motors") M1 to Mn.
Is detected, and the operation of the SCR drive unit 1 is controlled according to the detected state. Then, the SCR driving unit 1 responds to the control by the starting unit 2 and controls the induction motor M1.
By controlling the voltage applied to Mn, the induction motor M1
The so-called soft start control is performed on Mn.

Under the control of the sequence controller 3, the start-up electromagnetic relays FM1 to FMn together with the SCR drive unit 1 together with the three-phase power source and the induction motors M1 to M1 under the control of the sequence controller 3.
It is connected in series with Mn (details will be described later). That is, the SCR drive unit 1 is operated for a certain period at the time of starting.
The three-phase voltage whose waveform is controlled by is applied to the induction motors M1 to Mn through the starting electromagnetic relays FM1 to FMn.

The electromagnetic driving relays BM1 to BMn are connected between the three-phase power source and the induction motors M1 to Mn,
As will be described later, the sequence controller 3 controls the three-phase power supply and the induction motors M1 to M after the start period elapses.
n is directly connected.

The sequence controller 3 comprises electromagnetic relays FM1 to FMn for starting and electromagnetic relays BM1 to B for operation.
The operation of Mn is controlled so that the induction motors M1 to Mn are started one by one. FIG. 2 shows a concrete circuit example of the sequence controller 3, and this concrete circuit example will be described below with reference to the figure.

First, the overall configuration will be briefly described. The sequence controller 3 shown in FIG. 2 is configured by a sequence circuit having an electromagnetic relay and a timer circuit as main components, and is shown in FIG. 3 in the circuit example
Since the induction motors of the units are sequentially started, the same sequence is basically configured for three units. The sequence controller 3 of this embodiment has two operation modes, a manual operation and an automatic operation.

That is, the manual operation is to start the induction motors one by one by sequentially depressing the manual start switches SW4, SW5, SW6. One induction motor is in a steady operation (the rated voltage is applied). The sequence is set such that the induction motor corresponding to the start switch is not started even if the other start switch is pressed until the operation state (in the operated state) is reached. The auto operation is an operation mode in which the three induction motors are sequentially started by setting the mode selection switch SW1 to the AUTO side and closing the auto start switch SW2.

Next, the operation of the sequence controller 3 will be described. First, the manual operation will be described. In this operation mode, the mode selection switch SW1
Is set to the MANUAL side, and the individual manual mode setting switches SW11 to SW13 are set to the MANUAL side. Then, the manual starting switch SW4 including a so-called push button switch is pressed. When the switch SW4 is pressed, the first electromagnetic relay R1, the first starting electromagnetic relay FM1, the interlock circuit IN
An AC voltage (220V) is applied to each of T1 and the overcurrent relay EOCR-1. as a result,
The a-contact R1a of the first electromagnetic relay R1 is closed, and the a-contact R1a and the first timer circuit T of the starting unit 2 are also closed.
B-contact TM1-1 and second timer circuit TM2 of M1
The AC voltage is supplied through the b-contact TM2-1 (see FIG. 2).

As a result, the first starting electromagnetic relay FM1
And the SCR drive unit 1 are connected in series between the three-phase power source and the induction motor M1, and the three-phase voltage whose voltage is controlled by the SCR drive unit 1 based on the control of the start unit 2 is the first start electromagnetic relay. It is applied to the induction motor M1 via FM1. FIG. 3 shows a timing chart of the main part of this device from the start to the rated voltage operation. The operation timing of the switch SW4 described above is shown in FIG. The operation timing is shown in (c) of the figure.
The operation timing of the first starting electromagnetic relay FM1 is shown in (v) of the figure, and the operation timing of the induction motor M1 is shown in (v) of the figure. Further, FIG. 3A shows a change (effective value) of the voltage applied to the induction motor M1 by the control of the SCR drive unit 1 via the first starting electromagnetic relay FM1.

After a lapse of a certain time from the start of the start by pressing the switch SW4, the a contact INT-1a of the first interlock circuit INT1 is closed (see FIG. 3D). Then, after that, the first starting electromagnetic relay FM1
The voltage applied to the induction motor 1 via the rated voltage becomes the rated voltage, and the a-contact ST of the starting portion 2 is closed by the starting portion 2 at a point of time (point A in FIG. 3). (See FIG. 3E). By closing the a-contact ST, an AC voltage is applied to the first operation electromagnetic relay BM1 and the first operation electromagnetic relay BM1.
Is activated.

As a result, the induction motor M1 is provided with this first
The three-phase rated AC voltage is applied through the contacts of the electromagnetic relay for operation BM1 (see FIGS. 1 and 3A). Even if this first electromagnetic relay for operation BM1 is in the starting state, the first electromagnetic relay for FM FM is started for a while.
1 is also in the operating state, and during this period, the first starting electromagnetic relay FM1 and the SCR are directly connected to each other, and the first
The operating electromagnetic relay BM1 is connected in parallel,
It is in a state of being connected between the three-phase AC power supply and the first induction motor M1 (see FIGS. 3F and 3C).

Further, when an AC voltage is applied to the first operation electromagnetic relay BM1, its a-contact BM1a is closed (see FIG. 3C), and thereafter, the first operation electromagnetic relay BM1a is closed. The power supply voltage is applied to the relay BM1 via the a-contact BM1a, and a so-called self-holding circuit is formed (see FIG. 2). Then, after a lapse of a certain time from the start of the operation of the first electromagnetic relay BM1 for operation, the b-contact TM1-1 of the first timer circuit TM1 is in the open state (see FIG. 3C). As a result, the first starting electromagnetic relay FM1 is in the non-excited state (see FIG. 3).
(See (i)), the SCR drive unit 1 is disconnected from the induction motor M1. Therefore, thereafter, the induction motor M1 will be connected to the three-phase AC power source only via the first operation electromagnetic relay BM1 (FIG. 3).
(See (f) and (v)). In this way, the operation of the first electromagnetic relay FM1 for start and the operation of the first electromagnetic relay BM for operation
By providing the period in which the operation of No. 1 overlaps, it is possible to shift from the starting state to the operating state at the rated voltage without causing a large current change.

After the induction motor M1 is completely operated under the rated voltage as described above, the a-contact TM1-2 of the first timer circuit TM1 is closed (FIG. 3).
(See ())). Therefore, even if the manual start switch SW5 is pressed before this, the induction motor M2 is not started. First timer circuit TM1
After the a-contact TM1-2 is closed (see FIG. 3 (C)), the manual start switch SW5 is pressed to start the induction motor M2 in the same manner as in the case of the induction motor M1 described above. This will be the case (see FIG. 3 (c)). Hereinafter, the starting of the induction motor M3 is basically the same, and the description thereof will be omitted.

Next, the automatic operation will be described. First, set the mode selection switch SW1 to AUTO side,
Then, the auto start switch SW2 is turned on. By turning on the switch SW2, an AC voltage (220) is applied to the first electromagnetic relay R1, and at the same time, the first starting electromagnetic relay FM1,
Interlock circuit INT1 and overcurrent relay EOC
An alternating voltage (220V) is applied to each of R-1. The subsequent operation is the same as the manual operation described above, and therefore the repetitive description is omitted here.

After the induction motor M1 is started by the automatic operation and brought into the rated voltage operation state, the a contacts TM1-3 of the first timer circuit TM1 are closed (FIG. 3).
(See (a)). As a result, the AC voltage is applied to the second electromagnetic relay R2 via the a-contact TM1-3, and as a result, the induction motor M2 is started in the same manner as in the case of the induction motor M1. And the induction motor M
After the second shifts to the rated voltage operation, the second timer circuit T
The a-contact TM2-3 of M2 is closed, and the induction motor M3 is started by exciting the third electromagnetic relay R3. In addition, (3) of FIG.
Indicates a period during which the induction motor M1 is in an operating state for starting, and FIG. 9 (s) indicates a stop period in that operating state. Further, although FIG. 3 mainly shows the timing at the time of starting the induction motor M1, the operation timing of the other induction motors is basically the same.

FIG. 4 shows an example of a specific circuit of the starting unit 2. The structure and operation of the starting unit 2 will be described below with reference to the figure. First, the starting unit 2 of this embodiment
Is a slip detection circuit (MOTOR SLIP SENSING CIRCUIT)
4. Phase detection circuit (PHASE DETECTOR) provided for each phase
CIRCUIT) 5a to 5c, a ramp signal generator (RAMP SIGNAL GENERATOR) 6a to 6c provided for each phase,
The SCR drive unit control circuit 7 is a main component.

The general operation of the starting unit 2 of the present embodiment will be described. A slip at the time of starting the induction motors M1 to Mn is detected by the slip detecting circuit 4, and the SCR drive unit 1 is detected according to the size of the slip. The pulse width of the gate signal applied to the gate of the SCR is determined, and the gate signal shown in FIG. 5 (h) is applied to the SCR by outputting a control signal from the SCR drive control circuit 7. To do so. As a result, the AC voltage as shown in FIG. 5 (i) is applied to each induction motor M1 to Mn via the SCR.

Next, the function and operation of each circuit will be described. First of all, the slip detection circuit 4 detects each induction motor M1.
The slip of ~ Mn is detected, and a voltage signal corresponding to the magnitude of the slip is output. Although its specific circuit configuration is omitted here, for example, the output of a rotation sensor that detects rotation is compared with a reference voltage corresponding to the rated rotation speed, and a voltage signal according to the comparison result is output. Such a circuit configuration is common and has a known circuit configuration.

The phase detection circuits 5a to 5c output the signals as shown in FIGS. 5B and 5C in synchronization with the polarity change of the voltage of the three-phase AC power supply. The ramp signal generators 6a to 6c output negative polarity ramp signals as shown in FIG. 5D in synchronization with the phase detection circuits 5a to 5c. The SCR drive unit control circuit 7 is composed of a soft start circuit unit 7a, a phase control integration circuit unit 7b, and a comparison circuit unit 7c.
The SCR drive unit 1 is controlled so as to gate the CR as shown in FIG.

The soft start circuit section 7a is an integrating circuit mainly composed of the IC1 and outputs a voltage gradually increasing to the negative electrode side as shown in FIG. 5 (e). The phase control integration circuit section 7b is configured by a so-called bridge T-type mirror integration circuit centered on the IC5 and a so-called active filter having a pass frequency of about 20 hertz or less. As shown in FIG. It outputs a negative staircase wave as shown.

The comparison circuit section 7c has a pair of two comparators configured to form a logical sum with diodes,
Three such circuits, that is, three phases are configured. For example, one set of circuit parts is a part mainly composed of the comparator ICs 7 and 8 in FIG.
The phase detection circuit 5a is compared with the signals a to 6c.
.About.5c output signals (the signals shown in FIG. 5C) are compared with the reference voltage, and the logical sum of the respective comparison outputs is obtained.

Next, the SCR drive unit control circuit 7 of this embodiment
The operation will be described with reference to FIG. First, at the start of the operation of this circuit, the output voltage of the IC5 forming the integrator is on the positive side of the negative reference voltage set at the non-inverting input terminal of the comparator IC3, and therefore the comparator IC3 The output is a predetermined negative voltage, which causes the transistor Q
1 and Q3 are made conductive. Then, as the output voltage of the IC 5 via the resistor 26, a negative voltage of -V1 (v) is output as shown in FIG. 5 (f).
The magnitude of -V1 (v) can be adjusted stepwise by adjusting the variable resistor P4.

After this, when the output voltage of IC5 exceeds the reference voltage of the non-inverting input terminal of IC2, IC2 outputs a predetermined positive voltage to render transistor Q4 conductive, and at the same time relay RY-1 operates. To do. The operation of this relay RY-1 closes its a-contact RY-1a, and the voltage determined by the division ratio of the variable resistor P5 and the resistors R28, 29 is the output voltage of the IC5 via the resistor 26. As a result, the non-inverted input terminals of the comparator ICs 8, 10, 12 have -V2 as shown in FIG. 5 (f).
The negative voltage of (v) will be applied.

After the output voltage of the IC5 via the resistor R26 becomes the above-mentioned -V2 (v), after a certain period of time elapses, as shown in FIG.
As shown in (f), -V3 (v) is the comparator IC8,
It is applied to each of the non-inverting input terminals 10 and 12. The negative voltage of −V3 (v) is obtained as a result of the output voltage of IC1 being integrated in IC5. In addition, the portion mainly composed of IC6 and Q2 is I
So-called AGC (Automatic Gain Contro) for C5
l), the output level of IC5 is IC
When the reference voltage at the non-inverting input terminal of 6 is exceeded, Q
2 is made conductive to short-circuit the series connection portion of the resistor 23 and the capacitor C7, and the feedback resistance value of the IC5 is lowered.

The signals shown in FIG. 5 (f) are input to the non-inverting input terminals of the comparator ICs 8, 10, 12 while the corresponding ramp signal generators 6a to 6a are input to the inverting input terminals. The ramp signal from 6c (see FIG. 5 (d)) is input and both signals are compared.

Eventually, the control signal from the SCR drive unit control circuit 7 is input to the SCR drive unit 1 so that S
A gate signal as shown in FIG. 5 (h) is applied to the CR from the SCR GATING circuit, and its conduction state is controlled. As a result, the induction motors M1 to Mn are as shown in FIG. 5 (i). An alternating voltage whose waveform is controlled is applied.

In this embodiment, the case where the start of a plurality of three-phase induction motors is controlled has been described as an example, but the present invention is
Not only the induction motor but also other motors can be similarly applied.

[0035]

As described above, according to the present invention,
When the voltage supplied to the electric motor is started, the voltage control means that gradually increases to the rated voltage is sequentially switched and connected to each electric motor, so that a dedicated start for each electric motor can be achieved. It is not necessary to provide a voltage control means for this, and therefore the configuration of the entire device is simplified.
Moreover, at the same time that the voltage is supplied to the electric motor through the voltage control means, there is a period during which the operating circuit opening / closing means that directly connects the AC power supply and the electric motor is operated, so that a smooth transition can be made from the start to the operating state of the rated voltage. Therefore, it is possible to ensure stable and reliable starting of the electric motor.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an overall configuration of an embodiment of a multi-starter for a three-phase induction motor according to the present invention.

FIG. 2 is a circuit diagram showing an embodiment of a sequence controller used in the multiple starter for the three-phase induction motor shown in FIG.

FIG. 3 is a timing chart of a main part for explaining the operation of the present apparatus.

FIG. 4 is a circuit diagram showing an example of a starting unit step start used in the multiple starting device for the three-phase induction motor shown in FIG. 1.

FIG. 5 is a timing chart in the main part for explaining the operation of the starting part shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... SCR drive part 2 ... starting part 3 ... sequence controller 4 ... slip detection circuit 5a-5c ... phase detection circuit 6a-6c ... ramp signal generator 7 ... SCR drive part control circuit 7a ... soft start circuit part 7b ... phase control Integration circuit section 7c ... Comparison circuit section

Claims (1)

[Claims] 1. A voltage control means for controlling a voltage applied to the electric motor according to a rotation state of the electric motor, and a plurality of starter circuit opening / closing circuits provided corresponding to the number of electric motors and connected in series with the voltage control means. Means, a plurality of operation circuit opening / closing means provided corresponding to the number of electric motors and connecting between the electric motors and the power source, and a plurality of starting circuit opening / closing means and the operation of the operation circuit opening / closing means An operation control means, wherein the operation control means sets one of the plurality of starting circuit opening / closing means in an operating state to start the operation between one electric motor and an AC power source. After connecting the operating circuit opening / closing means and the voltage control means in series, and after a certain period of time, one of the plurality of operating circuit opening / closing means is put into an operating state, and the operating circuit opening / closing means is opened. AC power supply and the above one A plurality of electric motors are sequentially started by successively performing a control operation in which the electric circuit is connected in series with the electric motors, and then the control operation for making the one starting circuit opening / closing means inoperative is repeated. Multiple starting control device for electric motors.