JPS61231806A - Magnetic levitation controlling method - Google Patents

Abstract

PURPOSE:To eliminate a cable and a battery to supply power source to a moving truck by connecting a resistor as a load of the secondary side coil, and inserting a transistor chopper circuit between the coil and the resistor. CONSTITUTION:Four secondary side coils 1-4 are respectively mounted at front and rear, right and left sides of the upper surface a truck 13, and gap sensors 5-8 are respectively mounted at the front ends of the front coils 1, 3 and the rear ends of the rear coils 2, 4. The primary side coils 9-12 are mounted at the positions corresponding to the secondary side coils 1-4 on the lower surface of a horizontal arm 18. A transistor chopper circuit C is inserted to between the secondary side coil B and a resistor R. The duty ratio of the circuit C is controlled in response to the output of a gap sensor D to maintain the gap constant.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a control method for maintaining a constant gap between a linear motor and a scale in a floating object using a linear motor or the like.

(Conventional technology) Conventionally, in order to keep the above gap constant, the output of the gap sensor was fed back to change the attractive force between the coils, but this type of technology requires expensive and heavy permanent magnets. In addition to the.

Many require a separate power source for the moving secondary electromagnetic coil (hereinafter referred to as the coil).

(Problem to be solved by the invention) When the floating body on which the movable secondary coil is installed is completely levitated and travels without contact with guide rails, etc., it is necessary to is important, and laying cables for power supply is inconvenient for completely contactless running.

Furthermore, even when batteries are mounted on a floating body to eliminate the need for cables, problems such as battery maintenance and replacement arise.

(Means for Solving the Problems) In order to solve the above problems, in the present invention, a resistor is connected as a component of the secondary coil installed on the traveling floating body, and the coil and the resistor are connected. Insert a transistor chopper circuit between them.

The transistor chopper circuit uses the output of the gap sensor to control the induced current generated in the coil flowing through the resistor. Accelerometers may also be used for more precise control.

(for writing) The basic principle and operation of the present invention are as follows.

In Figure 1, the resistor (
When R) is infinite, that is, there is no connection, the current flowing is zero and the attractive force between the negative secondary coils (A) and (B) is maximum. If R=O, that is, the secondary coil (B) is short-circuited, the attractive force will be minimum.

If you make the resistance value variable, the current will change and the attraction force will also change.

Instead of physically changing the resistance value, set the resistance value to the minimum (maximum current), and then connect the secondary coil CB as shown in Figure 2.
A transistor chopper circuit (
Add C).

The gap between both coils (A) and (B) becomes narrower, and the gap sensor (C) connected to the chopper circuit (C)
If the output of D) increases, the chopper circuit (C)
The duty ratio changes, and the current flowing through the resistor (R) decreases. As a result, the suction force decreases and the gap widens. If the gap is too wide, use the gap sensor (D)
The output of (C) decreases, and the duty ratio of (C) of the chopper circuit is reversely changed to increase the current.

To set the gap to a value in advance.

The duty ratio may be determined appropriately. The chopping frequency of the chopper circuit (C) needs to be determined appropriately, taking into consideration the frequency of the power supply flowing to the secondary coil (A), vibrations and noise during suction, etc.

(Example) The embodiment shown in FIG. 3 will be described below.

Four secondary coils (
1) Install (2), (3), and (4), and install the front coil (
Gap sensors (5) (7) (6) (8) are installed at the front end of 1) (3) and the rear end of rear coils (2) (4), respectively.
) is installed.

At locations corresponding to the secondary coils (1), (2), (3), and (4) on the lower surface of a horizontal arm (18) protruding from the upper end of a column (17) installed on the floor (16), - Install the next coils (9), (10), (11), and (12). Thus, when an alternating current is passed through the secondary coil, an attractive force is generated between the coil and the secondary coil, and the cart (13) floats while maintaining a constant gap between both coils.

In order to run the trolley (13) in the horizontal direction, the trolley (13) is
3) At the center of the upper surface, there is a linear motor scale (14) facing in the front-rear direction, and to face this, on the lower surface of the horizontal arm (18) there is a linear motor scale (15).
) is installed.

Note that as the trolley (13) travels, the relative positions of the negative side and secondary side coils shift, so the negative side coil is installed over the entire traveling range, and the current is applied to the secondary side coil. This is so that it can occur.

Since only a small amount of power is required for the gap sensor, it can be obtained from the power generated in the secondary coil through a constant voltage power supply.

(Effects of the Invention) This invention enables a moving cart to be completely suspended in the air without using cables or batteries to supply power.
Since a fixed position can be maintained, for example, when used in a conveyance system in a clean room, there are no elements that generate dust, and maintenance is easy.

[Brief explanation of drawings]

1 and 2 are circuit diagrams for explaining the present invention in detail, FIG. 3 is a plan view schematically showing an embodiment of the present invention, and FIG. 4 is a front view. (1) (2) (3) (4) Secondary coil (5) (6) (
7) (8) Gap sensor (9) (10) (11)
(12) - Next coil (13) Cart (14) Linear motor scale (15) Linear motor (16) Floor (17) Column (18) Horizontal arm Patent applicant's agent Patent attorney 7 A □ -,, ,g
, /, 4 Yong Figure 1 Figure 2

Claims (1)

[Claims] Mutual induction is achieved between the primary electromagnetic coil installed on the ground or on the floor and the secondary electromagnetic coil that is movable with a constant gap, using a variable resistor or transistor chopper connected as a load for the secondary electromagnetic coil. The current generated by the coils is controlled to change the attractive force between the primary and secondary electromagnetic coils, and the outputs of the gap sensor, acceleration sensor, etc. are fed back to create a connection between the two coils.
A magnetic levitation control method characterized by maintaining a set constant gap.