JPH04282086A - Driving control method for motor-driven valve by two-winding motor - Google Patents

Abstract

PURPOSE:To provide a motor-driven valve driving control method preventing water hammering at the totally closed time and enabling the stable conversion to the target opening/closing degree rapidly without chattering. CONSTITUTION:An induction motor is provided with two-winding structure formed of windings 1, 3. At the normal operating time, A.C. power is applied to both windings 1, 3. At the low-speed operating time, A.C. power is applied to one winding, and D.C. power is applied to the other winding.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a drive control method for an electric valve using an induction motor for driving an on-off valve.

0002

[Prior Art] In the opening/closing operation of an electric valve, it is necessary to slow down the closing operation just before closing to prevent water hammer, and when it is necessary to change the opening/closing speed of the valve in this way, AC power has traditionally been used as is. However, the speed is controlled by adjusting external resistance, but this method has the disadvantage that it is difficult to apply rapid deceleration or braking.

[0003] Another method of reducing the speed is to switch the number of poles, which is described in Japanese Utility Model Application No. 57-181970, but with this method, it is not possible to achieve a low torque value, and the valve is close to fully closed. The drawback is that it is difficult to operate at a sufficiently low speed, and it is also difficult to control the speed.

There is a DC braking method in which DC power is applied after cutting off AC power to the induction motor, but although it can be used for simple braking and stopping, it is difficult to operate stably at low speeds, and it is difficult to control the speed. The disadvantage is that it is not easy.

[0005]

[Problems to be Solved by the Invention] The problem of the present invention is to eliminate the drawbacks of the conventional technology, generate strong braking force, quickly shift to low speed, and enable stable low-speed operation at any low speed. An object of the present invention is to provide a method for controlling the drive of an electric valve using a two-winding motor.

[0006]

[Means for Solving the Problems] The gist of the present invention that solves the above problems is that in the opening/closing operation of a valve driven by an induction motor, the induction motor has two windings, and during normal operation, two windings are used. AC power is applied to both windings, and at low speeds, AC power is applied to one winding and DC power is applied to the other winding, thereby applying braking force to the motor and driving it at low speed. The present invention provides a method for controlling the drive of an electric valve using a two-winding motor.

[0007]

[Operation] In the present invention, during starting and during opening/closing, alternating current power is applied to both windings of the induction motor to open or close the valve at high speed. To avoid water hammer when the valve is close to being fully closed, AC power is applied to only one of the two windings, and DC power is applied to the other winding to generate a strong electromagnetic braking force, which causes the valve to close. Rapidly reduce the closing speed and move slowly at a low speed.

Furthermore, the value of the low speed can be increased or decreased arbitrarily by controlling the direct current, making it easy to control the speed during low speed operation. Also, even when the valve is close to fully open, the opening speed can be reduced in the same manner as when fully closed.

[0009]

[Example] Hereinafter, an example will be explained based on the drawings. In the figure, 1 and 3 are windings, 2 is a brake unit, F, R, H, L
is a relay, B1 is a stop button, B2 is a high speed button, B3
is the low speed button, B4 is the forward rotation button, B5 is the reverse rotation button,
f is the relay contact of relay F, l is the relay contact of relay L, r is the relay contact of relay R, h is the relay contact of relay H, PR, PS, PT are AC power terminals, V1, V2, U
1, U2, W1, and W2 indicate terminals of windings 1 and 3.

In this embodiment, when high speed is desired, pressing the high speed button B2 closes the relay contact h and connects the two windings 1 and 3.
Both are energized and rotated at high speed to open and close the valve at high speed (rated speed).

Next, when the valve is close to fully closed and the valve is moved at a low speed to avoid water hammer, or when the valve is driven at a low speed to avoid chattering at the desired valve opening, Press the low speed button B3.

[0012] When the low speed button B3 is pressed, the low speed relay L
operates, relay contact l closes and relay contact h opens, applying direct current to one winding 3 and applying alternating current to the other winding 1, giving braking force to the induction motor and causing it to suddenly decelerate. The valve slowly opens fully or reaches a predetermined target opening/closing degree at a low valve opening/closing speed (see FIGS. 2 and 3). Therefore, water hammer does not occur during the fully closed operation, and when converging to the target opening/closing degree, the convergence can be quickly achieved without causing chattering.

Next, FIG. 4 shows the torque α generated when AC power is applied to the second winding, the high-speed operation point HD, the torque β generated when AC power is applied to the first winding, and the DC power applied to the first winding. Braking torque γ, generated torque β generated when applying
and the braking torque γ, the resultant torque δ, the low speed operation point LD,
Load torque LT is shown.

As can be seen from this, the composite torque δ generated when AC power is applied to one winding and DC power is applied to the other windings is small, and the speed becomes equal to the load torque LT.
In other words, the low-speed operating portion LD can be made extremely slow. Furthermore, by controlling the direct current, the value of the braking torque γ can be arbitrarily increased or decreased according to this curve pattern, making it easy to control the speed during low-speed operation.

On the other hand, when the torque β is generated by only one winding, the operating speed is still at a high speed value, and it can be seen that using only one winding is insufficient.

[0016]

[Effects of the Invention] As described above, according to the present invention, the valve can be opened and closed at low speed by quickly shifting from high speed to low speed, thereby preventing water hammer when fully closed, and quickly converging to the target opening/closing degree. This has the effect of being able to perform stably without chattering.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an embodiment of a method for controlling the drive of an electric valve using two windings of the present invention.

FIG. 2 is an explanatory diagram showing the valve opening/closing speed to fully close.

FIG. 3 is an explanatory diagram showing a state of convergence to a target opening/closing degree.

FIG. 4 is an explanatory diagram showing the relationship between generated torque and speed when AC/DC power is applied to the second winding and the first winding.

[Explanation of symbols]

1 Winding wire 2 Brake unit 3 Winding wire B1 Stop button B2 High speed button B3 Low speed button

Claims (1)

[Claims] Claim 1: In the opening/closing operation of a valve driven by an induction motor, the induction motor has two windings, and during normal operation, AC power is applied to both of the two windings, and during low speed, one winding is applied. 1. A method for controlling the drive of an electric valve using a two-winding motor, characterized by applying AC power to one winding and applying DC power to the other winding, thereby applying braking force to the motor and causing it to operate at a low speed.