JPS5927176B2 - Control method of moving coil actuator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of controlling a moving coil actuator that eliminates a dead zone.

As shown in Fig. 1, the configuration of the moving coil type actuator is as follows: a plunger guide tube 1 made of non-magnetic material, a plunger 2 made of ferromagnetic material, a forward direction coil 3, a reverse direction coil 4, and the above-mentioned plunger. It consists of a coil 5 for detecting relative displacement between a direction coil and a plunger and a coil for reverse direction, a connecting rod 6 between the coils, and a core 7 for detecting relative displacement connected to the plunger with a plunger connecting rod 8. , the reverse direction side coils each have a dedicated power source, and the two coils, the relative displacement detection coil, and the connecting rod are integrated into a plunger guide tube by a drive mechanism (not shown) consisting of a motor, gears, etc. This movement is called a driving body.

The plunger and the core for detecting relative displacement are connected as described above, and in response to the excitation of the forward direction coil 3 and reverse direction coil 4, the plunger and the core for detecting relative displacement are connected magnetically through the plunger guide tube 1. When coupled, an electromagnetic force acts, and the moving body follows the driving body.

Here, for example, in the apparatus shown in FIG. 1, the forward direction refers to the upper direction in the drawing, and the reverse direction refers to the lower direction.

Further, current in the same direction is always passed through the forward direction coil 3 and the reverse direction coil 4.

The reason why the coil 3 is called "for forward direction" is because when moving the plunger 2 in the forward direction, a large current is passed as described later, and the coil 4 is called "for reverse direction". This is to cause a large current to flow when moving the plunger 2 in the opposite direction.

Note that this connected core and plunger are called a driven body.

The relative displacement detection coil 5 and the relative displacement detection core 7 constitute a differential transformer type displacement detector via a non-magnetic plunger guide tube 1, and the mutual positional relationship can be detected without contact.

The above-mentioned actuator is controlled by controlling the output voltage or current of the power source of each of the forward direction coil and reverse direction coil by the relative displacement signal from the relative displacement detection coil 5 regardless of the movement of the driving body. Although,
Therefore, a dead zone occurs in which the force in the opposite direction is small immediately after the moving direction of the driving body is reversed, and the tracking of the driven body is delayed.

To explain the phenomenon described above with reference to Figures 2a, b + C and d, as the driver, which was initially in equilibrium, moves in the forward direction (Figure 2a), the relative displacement between the driver and the driven body changes. (Fig. 2d), the voltage or current of the forward coil increases in response to the relative displacement signal.
b), the voltage or current of the reverse coil decreases (
(Fig. 2C), when the driving body reaches an equilibrium state during movement and then moves in reverse (Fig. 2a), the driven body cannot follow it due to the small force in the opposite direction and the frictional force caused by the radial attraction force. A dead zone occurs without moving, which increases the relative displacement (Fig. 2d), and the voltage or current of the forward coil does not decrease until an equilibrium state is reached during movement (Fig. 2b).
The voltage or current in the reverse coil increases (Figure 2c).

Here, the equilibrium state means that the load (weight, fluid force, friction, etc.) acting on the driven body and the electromagnetic force generated by coil excitation are balanced, and the relative displacement between the driving body and the first driven body changes. It refers to the state of not doing anything.

In view of the above-mentioned current situation, the present invention provides a control circuit for each of the forward direction and reverse direction coils, and controls the coils based on an operation signal and a feedback signal for the relative displacement of the driving body and driven body, thereby controlling the coils when the driving body is reversed. An object of the present invention is to provide a method of controlling a moving coil type actuator that eliminates a dead zone by increasing the force in the opposite direction of the actuator.

Next, to explain an embodiment of the present invention, as shown in FIG. The movable coil type actuator is driven by feeding back the relative signals of the driving body and the driven body, and adding the driving body operation signal 15 and status signal 16 to the mechanism control circuit 14 of the coil drive mechanism 13 to control the movable coil type actuator. This increases the force in the opposite direction when the body is turned over, and this can be explained in detail using the diagram shown in Figure 4.1.
When the drive body reverses from the forward direction to the reverse direction, the voltage or current of the forward direction coil is decreased and the voltage or current of the reverse direction coil is increased in synchronization or with a time delay based on the drive body operation signal. When the relative displacement increases during movement, the voltage or current of the forward and reverse coils is increased or decreased by the relative displacement signal to maintain the relative position.

Further, depending on the state of the load, the coil drive mechanism is operated, and the voltage or current of the forward and reverse coils is controlled to perform control.

In this way, no dead zone occurs at all as shown in the relative displacement diagram shown in FIG.

Furthermore, it is possible to improve controllability by superimposing a dither circuit, for example, a low frequency sine power supply in the case of direct current, on each of the coil power supply control circuits described above. There are the following methods including:

i.e. on/off voltage or current control in synchronization with forward or reverse driving signals or with a time delay, average voltage or current control with pulse width control, voltage or current control with driver and driven object relative displacement feedback signals. , voltage or current control using dither, voltage or current control using some combination of the above, and voltage or current control similar to the above methods.

[Brief explanation of the drawing]

Fig. 1 is a vertical side view of a moving coil type actuator;
Figures 2a, b, c, and d are diagrams showing the interrelationships among the driving body, each coil voltage or current, the driving body, and the relative position of the driven body according to the conventional control method. The block diagram illustrating the example, FIG. 4, is also a diagram showing the mutual relationship among the driving body, coil voltage or current, driving body, and relative position of the driven body. 3... Coil for forward direction, 4... Coil for reverse direction, 9... Coil power supply for forward direction, 10.
...Forward coil power supply control circuit, 11...
... Coil power supply for reverse direction, 12 ... Coil power supply control circuit for reverse direction, 13 ... Coil drive mechanism,
14... Coil drive mechanism control circuit, 15...
...Driver operation signal, 16...Status signal.

Claims (1)

[Scope of Claims] 1. A forward coil and a reverse coil disposed outside the plunger guide tube and connected to be movable in the axial direction by a drive mechanism, and a forward coil and a reverse coil disposed within the plunger guide tube corresponding to each of the coils. and a plunger movable in the axial direction, and when a forward operation signal is generated, increases the average current of the forward coil in synchronization with the signal or with a predetermined time delay,
Decrease the average current of the reverse direction coil, and when a reverse direction operation signal is generated, increase the average current of the reverse direction coil in synchronization with the signal or with a predetermined time delay, and reduce the average current of the forward direction coil, and A method for controlling a moving coil actuator, characterized in that in current control when each of the signals is generated, the relative position of each coil and the plunger is detected, and the average current of each of the coils is feedback-controlled based on the relative position signal. .