JP2999452B2 - Concrete vibrator drive power supply - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a concrete vibrator drive power supply which can be used for driving an induction motor and a synchronous motor.

[0002]

2. Description of the Related Art To drive a concrete vibrator,
Both induction motors and synchronous motors are used, but conventionally these motors each require a dedicated drive device. In driving a synchronous motor, one drive device is used for one motor in order to prevent loss of synchronism.

Conventionally, a power supply device capable of driving both an induction motor and a synchronous motor is disclosed in Japanese Patent Application No. Hei.
The technology disclosed in the specification of Japanese Patent No. 5 has been proposed. This has a circuit for detecting the position of the rotor using the neutral point from the star-shaped connection stator of the synchronous motor, and switching between the induction motor and the synchronous motor is performed by an external circuit.

In a conventional synchronous motor drive power supply device, when two synchronous motors are connected to one inverter, the two units are simultaneously soft-started (zero-start).
In this case, both can be driven. However, if the second motor is forcibly started after the first motor is started, the second motor may not be able to synchronize and may not be driven.

[0005]

Problems to be Solved by the Invention Japanese Patent Application No. Hei 4-100
According to the technology of No. 215, one drive device can drive both the induction motor and the synchronous motor, but cannot perform automatic switching, and one drive device can drive a plurality of synchronous motors. Cannot be driven. Further, as described above, a plurality of synchronous motors connected to one drive device cannot be driven at any time. A first object of the present invention is to drive an induction motor and a synchronous motor so that they can be automatically switched by one drive device, and a second object is to drive a plurality of synchronous motors by one drive device. , Respectively, at any time.

[0006]

The invention of claim 1 solves the first problem. The concrete vibrator driving device includes a three-phase frequency conversion circuit, a phase difference detection circuit, an initial potential circuit that generates a potential adjusted for driving the induction motor in an initial state, and an oscillation that constitutes the three-phase frequency conversion circuit. A changeover switch that switches a connection with a circuit to the phase difference detection circuit and the initial potential circuit, a changeover circuit having the changeover switch and a step-out detection circuit, and a connection connector that can connect both an induction motor and a synchronous motor. Wherein the step-out detection circuit detects step-out due to the connection of the synchronous motor, and the changeover switch is connected to the phase difference detection circuit side based on the output signal. According to a second aspect of the present invention, the phase difference detection circuit is configured to detect the induced electromotive force of the synchronous motor without using the neutral point, and the motor can be driven only by three lines of U, V, and W,
The circuit configuration can be simplified. According to a third aspect of the present invention, there is provided a plurality of synchronous motors, further comprising a circuit for detecting an output current of the three-phase frequency conversion circuit when the synchronous motor is driven, and adding a bias corresponding to the output current to an output signal of the phase detection circuit. Can be driven.

The synchronous motor of the present invention is preferably a permanent magnet type synchronous motor in that the induced electromotive force is easily taken out. In the power supply device of the present invention, a sensor for the electric motor is not required for control. However, even a motor with a sensor can be controlled by a circuit configuration using no sensor.

[0008]

In the present invention, when the power of the driving device is turned on, the changeover switch always drives the induction motor.
Closed to the initial potential circuit side. Therefore, if the induction motor is connected to the connection connector, the induction motor is driven as it is. On the other hand, when the synchronous motor is connected to the connection connector, the synchronous motor loses synchronism when the power is turned on. This step-out is detected by the step-out detection circuit, and the changeover switch is automatically closed to the phase difference detection circuit side by the output signal. Thereby, the phase difference between the output from the three-phase frequency conversion circuit and the synchronous motor is detected, and the signal is output to the frequency conversion circuit, so that the synchronous motor is driven.

According to the third aspect of the present invention, an output current of the three-phase frequency conversion circuit is detected, and a bias corresponding to the output current is added to an output signal of the phase difference detection circuit, so that the output is controlled to delay angle control. Then, the output frequency of the driving device decreases. Therefore, the retraction operation of the rotor of the motor in the step-out state is performed, and the plurality of motors are stably controlled.

[0010]

First Embodiment In FIG. 1, a three-phase frequency conversion circuit 4 includes a voltage-controlled oscillation circuit 4a and a commutation control circuit 4b.
The output side is connected to the connection connector 5 by three connectors of U, V, and W. This connector 5 can be shared by the induction motor 12 and the synchronous motor 13. A phase difference detection circuit 6 is connected to the three connectors. The phase difference detection circuit 6 detects the induced electromotive force of the synchronous motor 13 without using a neutral point, and detects the phase difference between the rotor of the synchronous motor and the output of the three-phase frequency conversion circuit. Reference numeral 9 in the figure is a switching circuit. This switching circuit is connected to a changeover switch 9a and the connector via a current transformer 8 so that the synchronous motor 13
Out-of-step detection circuit 9b for detecting out-of-step. The changeover switch 9a connects an initial potential circuit 7 for generating a potential adjusted for driving an induction motor and the oscillation circuit 4a in an initial state, and is synchronized with the out-of-step detection circuit 9. When a step-out of the motor is detected, the signal is automatically switched to connect the phase difference detection circuit 6 and the oscillation circuit 4a in response to the signal.

In the above embodiment, when the induction motor 12 is connected to the connector 5, the output of the initial potential circuit 7 is frequency-converted by the three-phase frequency conversion circuit 4 and output to the induction motor 12. The induction motor 12 is driven. When the synchronous motor 13 is connected to the connector 5, the switch is closed to the initial potential circuit 7 when the power is turned on.
The second drive current is output, and the synchronous motor 13 steps out. This step-out is detected by the step-out detection circuit 9b, a switching signal is output, and the change-over switch 9a operates to close to the phase difference detection circuit 6 side. Therefore, a loop incorporating the phase difference detection circuit 6 is formed in the driving device, and the synchronous motor is driven.

In the above embodiment, the phase difference detection circuit 6 detects the induced electromotive force of the synchronous motor 13 without using the neutral point, and compares the phase difference between the rotor of the synchronous motor and the output of the three-phase frequency conversion circuit. U, V,
The motor can be controlled only by the three wires W, and the circuit configuration can be simplified. Note that it is not essential to detect using a neutral point.

FIG. 2 shows an additional circuit part according to a third aspect of the present invention. A motor-on detection circuit 10 is interposed between the current transformer 8 and the oscillation circuit 4a interposed in the output connector of the three-phase frequency conversion circuit 4. Reference numeral 11 in the figure
Is an intermediate switch attached to the motor. In the above, the three-phase frequency conversion circuit 4
, Is inverted by the motor-on detection circuit 10 to be converted into a control bias, and is added to the output signal of the phase difference detection circuit 6 as a bias.

If another synchronous motor 14 is connected while the synchronous motor 13 is being driven (the intermediate switch 11 is turned on), the output current increases.
Is input to This signal is inverted, added as a bias to the output signal of the phase difference detection circuit 6, and input to the oscillation circuit 4a. For this reason, the process shifts to the delay angle control, and the output frequency from the three-phase frequency conversion circuit 4 is reduced, so that the synchronous motor 14 inserted later is started by the rotor being pulled in by the low frequency. When the motor 14 is started, the bias is reduced, and the driving of the motor returns to the advance angle control.

[0015]

Embodiment 2 FIG. 3 shows an embodiment shown in FIG.
The circuit of FIG. 2 is incorporated in the embodiment of FIG. In the figure, reference numeral 1 denotes a commercial frequency power supply, 2 denotes a power-on switch of a three-phase frequency conversion circuit, 3 denotes a rectifier circuit, and
2 denote the same components.

In this embodiment, if the induction motor 12 is connected when the power is turned on, the induction motor 12 is driven in the initial state, and then when the synchronous motors 13 and 14 are connected, the step-out is detected. As a result, the changeover switch 9a is switched, a circuit including the phase difference detection circuit 6 is formed, and the synchronous motor starts up, as in the embodiment of FIG. Then, the motor input detection circuit 10
When the other synchronous motor 14 is turned on while the synchronous motor 13 is being driven, the output current obtained by the current transformer 8 is converted into a control bias, and the process shifts to delay angle control to shift to a three-phase frequency conversion circuit. 4, the synchronous motor 4 can be driven smoothly.
That is, as shown in FIG. 2, it is possible to drive a plurality of synchronous motors.

[0017]

According to the present invention, the switch for closing the induction motor drive circuit in the initial state closes the synchronous motor drive circuit by detecting the step-out of the synchronous motor. In addition to being able to share the drive of the induction motor and the drive of the synchronous motor, a circuit state suitable for each drive can be automatically selected. Therefore, if the motor to be used is connected and the power is turned on without being conscious of the type of the motor, any of the motors can be driven without performing any special operation. According to the invention of claim 3, a plurality of synchronous motors can be driven by one drive device. Therefore, the present invention is suitable for driving a concrete vibrator that uses both an induction motor and a synchronous motor as appropriate and drives an appropriate number of synchronous motors out of a plurality of units.

[Brief description of the drawings]

FIG. 1 is a circuit diagram according to a first embodiment of the present invention.

FIG. 2 is a circuit diagram of an additional circuit.

FIG. 3 is a circuit diagram of a second embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Commercial frequency power supply 2 Power-on switch 3 Rectifier circuit 4 Three-phase frequency conversion circuit 4a Oscillation circuit 4b Commutation control circuit 5 Connector 6 Phase difference detection circuit 7 Initial potential circuit 8 Current transformer 9 Switching circuit 9a Switching switch 9b Step-out detection Circuit 10 Motor turning-on detection circuit 11 Intermediate switch 12 Induction motor 13 Synchronous motor 14 Synchronous motor

Continuation of the front page (56) References JP-A-10-28390 (JP, A) JP-A-63-202296 (JP, A) JP-B-57-3307 (JP, B2) Jiko 6-37169 (JP) , Y2) (58) Field surveyed (Int.Cl. ⁷ , DB name) H02P 7/74

Claims (3)

(57) [Claims] 1. A three-phase frequency conversion circuit having a transmission circuit and a commutation control circuit, and a phase detecting means for detecting an induced electromotive force of a synchronous motor and detecting a phase difference between a rotor and an output current of the three-phase frequency conversion circuit. A phase difference detection circuit, an initial potential circuit that generates an electric current adjusted for driving the induction motor in an initial state, and a changeover switch that switches connection between the transmission circuit to the phase difference detection circuit and the initial potential circuit. On the output side of the changeover switch and the three-phase frequency conversion circuit
A switching circuit having a step-out detection circuit connected thereto, and a connection connector capable of connecting both the induction motor and the synchronous motor, wherein the step-out detection circuit detects step-out due to connection of the synchronous motor, and A concrete vibrator drive power supply device, wherein the changeover switch is connected to the phase difference detection circuit side by an output signal. 2. The phase difference detection circuit according to claim 1, wherein the induced electromotive force of the synchronous motor is detected without using a neutral point.
The described concrete vibrator drive power supply 3. The circuit according to claim 1, further comprising a circuit for detecting an output current of the three-phase frequency conversion circuit when the synchronous motor is driven, and adding a bias corresponding to the output current to an output signal of the phase detection circuit. Concrete vibrator drive power supply