JPH0652686B2 - Non-contact power transformer - Google Patents

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention relates to an electromagnetic coupling device, and more specifically, it provides a relative motion and a minimum reaction force between primary and secondary windings. It concerns a non-contact power transformer that occurs.

(2) Related Art The present invention described below is particularly effectively applied when electric power is applied from a stationary position to a movable position with a minimum interaction between a fixed component and a movable component. The invention is magnetically suspended, mainly when slight disturbance forces impact the magnetic control forces and when movements of up to 6 degrees of freedom are required over a restricted area. It is applied to transfer power through an interface.

An electromagnetic coupling device according to the prior art for coupling electromagnetic energy through a moving boundary or interface is constituted by a solenoid and a rotary transformer type structure. U.S. Pat. No. 4,117,436 "Torqueless Relative Movable Transformer Winding" discloses a primary winding and a secondary winding axially arranged on a common axis and surrounded by a magnetic core made of a high magnetic permeability material. Is applied to perform relative rotational movement limited between the first and second transformer windings about the axis. The disadvantage of this device is
That is, the range of relative motion degrees of freedom is limited. Another structure is disclosed in U.S. Pat. No. 4,321,572, in which the rotary transformer of the structure has a fixed primary winding and a rotatable two winding through a gear in the core structure. And a secondary winding. The invention mainly allows a complete degree of freedom of rotation without considering movement around other axes. However, the presence of an air gear trap in the magnetic core in the above invention significantly reduces the magnetizing inductance with respect to the leakage inductance, thereby reducing the electrical performance, and thus increasing the excitation power and device capacity to deliver a given power. Is required, resulting in reduced efficiency.

The present invention improves on the prior art by providing a non-contact structure that can move in six degrees of freedom, where the actual control applied to a fixed structure attached thereto. Only a slight reaction force is generated with respect to the force, no air gear trap is required in the magnetic core, and high efficiency is provided over the required movement region.

(3) Outline of the Invention According to the present invention, relative movement between a closed magnetic core substantially free of an air gear, a first winding, and the first winding and the second winding is provided. A non-contact power transformer having the secondary winding placed in the magnetic core is provided. The first winding is fixed, but the second movable winding has a considerable degree of freedom of movement over a restricted area and is positioned radially with respect to the first winding. Has been done. The device provides a substantially constant flux coupling between the two windings over the region of motion of the second winding.

In a preferred embodiment, a support member for connecting the second winding to a support movable structure is fixed to the second winding, and the magnetic core connects the support structure to the second winding. It is constituted by a cylindrical ferrite having an annular plate with an opening for connecting to the wire.

In another preferred embodiment, the present invention is applied to a magnetically actuated suspension system for transferring power between stationary and moving structures.

(4) Embodiment As described above, the non-contact power transformer according to the present invention needs to transfer the electric power to the suspended value load by minimizing the interaction with the magnetically suspended interface. It is particularly suitable for use in suspension systems. This is
This is especially important if the suspension is of the magnetic type. It is highly desirable to provide full freedom of movement, albeit on a restricted area, and to reduce any mechanical forces and electrical disturbances that interact with the suspension system. Friction losses are reduced by electromagnetic coupling because slip rings and brushes, or flexures, etc., which increase the friction and reaction forces applied to the suspension are eliminated.

Furthermore, since it is also intended to be applied to a space environment where heat dissipation is important, a considerable amount of power must be transmitted with high efficiency.

Now, FIG. 1A shows a normal two-winding transformer.
The primary coil 10 and the secondary coil 12 are sealed in a magnetically permeable magnetic core 14, and a magnetic circuit for connecting the primary coil and the secondary coil is formed in the magnetic core. All parts are fixed to each other and no air gears are required in the magnetic path of the magnetic core. Such a transformer can be formed into a cube or a cylinder depending on whether the magnetic core is formed of a laminated body such as ferrite or a cast body.

FIG. 1B shows a normal rotary transformer constructed by the concept of a cylindrical body, in which the coil 16 and a part of the magnetic core 18 rotate, and the coil 20 and a part of the magnetic core 22 partially move. It is fixed. Air gear trap 24 in the magnetic core
Thus, the secondary coil can perform rotational movement with the degree of freedom of uniaxial rotation. The magnetic path 26 applied to the gear produces a significant disturbance force when the rotor is moved from its center position. This device is disclosed in U.S. Pat. No. 2,4, issued Dec. 23, 1947, assigned to the applicant.
No. 32,982.

FIG. 1C shows a further improved device of the above-mentioned patent No. 4,321,572. In the device, a magnetic core 28 surrounds fixed windings 30 and 31 attached thereto, which winding is provided with an air gear tap 32 arranged to rotate a single axis of a secondary winding 34. There is. Only the secondary coil is movable and does not include any magnetic core. The primary coils 30 and 31
And the iron core 28 are fixed. The air gear 32 is positioned inside a channel that extends laterally of the axial hole, thereby isolating the gear 32 from free space and reducing leakage flux from the outside. The air-core secondary coil does not require any relative movement, i.e. flux transfer, between the magnetic paths of the movable core,
Thus, it produces significantly lower forces on the movable body than the device of FIG. 1B. However, the magnetic core gear 32 suppresses the electrical performance as described above, and by isolating the magnetic core gear 32 in the axial hole, the degree of freedom of uniaxial rotation of the transformer is limited. It

In the transformer of US Pat. No. 4,117,436, the primary and secondary coils are axially aligned on the spindle, allowing uniaxial rotational movement in a confined area. However, none of the trans-structures exhibits the 6 degree of freedom as provided by the present invention.

FIG. 1D is a sectional view of the present invention. The magnetic core 36 is constituted by an annular pot-shaped housing 38 and a cover plate 40, but the interface 42 thereof is not provided with any air gear. Primary coil 44
Is fixed in the housing 38 of the magnetic core. The secondary coil 46 is positioned for free movement in all directions over the restricted area. The secondary coil 46 supports structural members 48 and 50.
Reference numerals 50 and 50 are attached to the secondary coil by providing clearance holes 52 in the cover plate 40 so as not to interrupt the magnetic circuit.

Since the secondary coil does not contain any magnetic material, the magnetic resistance generated by the magnetic flux is eliminated between the iron parts separated by the gear. In the prior art,
The magnetoresistive force is a source of undesired force, and its elimination allows a much better performing device.

Secondly, there is the interaction of the stray fields by the primary and secondary coils in the coil space, which causes a significantly undesired force. If the secondary coil is centered in the coil space, there is a symmetrical force balance and no net force is exerted on the secondary coil. However, when the secondary coil is moved either radially or axially, an undesired force with a magnitude proportional to the displacement is exerted on the secondary coil. Since these undesired forces are a function of the uniformity of the stray field, by increasing the mechanical clearance around the secondary coil above the desired coil motion, as will be explained later with respect to FIG. The undesired force can be further reduced.

The undesired force exerted on the secondary coil is due to the interaction of the stray flux fields of the primary and secondary coils in the coil space. These unwanted forces can be further reduced by noting the uniformity of the primary coil leakage field in the space occupied by the secondary coil. FIG. 6 shows the leakage flux of the primary coil in the coil space of the transformer according to the invention both in its direction and in its magnitude, and also shows the envelope of the desired secondary coil movement. If the primary stray magnetic field is perfectly uniform in magnitude and direction over the desired secondary coil motion, then there will be no force. However, as can be seen from the drawing, the stray magnetic field is strong in the primary coil but weak in the point away from the primary coil. One way to improve the uniformity of the stray field within the operating region of the secondary coil and thus reduce the force is to increase the mechanical clearance to be much larger than the desired secondary coil motion. .

FIG. 2 is a perspective view of a preferred embodiment of the present invention with portions removed to show the major components, showing their relative position within the device. The illustrated configuration is for showing an embodiment, and is not limited to this. Therefore, axial holes for positioning, for example supports, have nothing to do with the effectiveness of the invention and are not required for other mounting devices. Other coil arrangements such as a fixed winding on the inner annular wall of the magnetic core 60 are also effective.

The closed magnetic core 60 includes a magnetically permeable annular ring 62 having a cavity 64.
Alternatively, the cover plate 66 may be used. The magnetic core is constructed and arranged in such a way that no air gear gap is generated in the interface with the cover plate. A first winding 68, which comprises a primary winding for receiving electrical energy, is fixed to the annular ring 62 of the magnetic core and is arranged in the cavity 64. A second electrical winding 70 positioned within the cavity 64 and radially spaced from the primary winding 68 is transmitted by electromagnetic coupling to a load (not shown). A secondary winding may be configured to supply the desired power. Magnetic core 60 and the first
Winding 68 and the second winding 70 form a magnetic circuit, and the second winding freely moves with respect to the magnetic core and the first winding, and It can be seen that they are positioned so as to maintain a substantially constant flux coupling regardless of their positional relationship to.

The closed magnetic core 60 made of ferrite material of the ceramic substrate is
It can be attached to a mount and power supply (not shown) along with the primary coil 68. The secondary coil 70 maintains at least a predetermined clearance from the primary coil 68 and the wall of the magnetic core 62, and is moved only when the secondary coil is closed in a substantially uniform magnetic flux coupling region. This minimizes the reaction force and supports 72
Is attached to the movable part, that is, the replacement load. The secondary winding 70 includes a magnetically permeable magnetic core 62 and a primary coil 6
It is positioned in an annular cavity 64 which contacts the wall of 8.
The closed magnetic core 60 surrounds both the primary coil 68 and the secondary coil 70 without providing any air gear trap, and provides a closed magnetic circuit for coupling magnetic flux from the primary coil to the secondary coil. Although a cylindrical core with an axial hole is shown, this is for illustration only and other shapes such as a solid cylindrical core or a rectangular core could be used.

A plurality of openings 74 are provided for accommodating the structural support 72 with clearances that allow the secondary coil 70 to move freely.

The reference numbers used next in FIGS. 3 and 4 indicate the same components. In the figure, a permeable magnetic core 80
Are formed by two or more constituent elements, and the primary coil 82 and the secondary coil 84 are incorporated in the closed magnetic core. The illustrated core is constituted by a pot core 86 having an essentially cylindrical body with an annular cavity 88, inside the pot core a primary coil 82 and a secondary coil 84. And are positioned. The primary coil 82 is attached to the outer peripheral wall of the pot-shaped magnetic core 86. The end plate 90 is placed in contact with the magnetic core 86,
It provides an essentially air-gapped magnetic circuit. The magnetic core assembly 80 is made of a high magnetic permeability material, and must be finished close to the allowable value so that no air gap is generated in the magnetic circuit. The end plate 90 has an opening 9
2 is provided and a support 94 fixed to the secondary coil extends through the opening 92. The support 94 must be made of non-magnetic material to ensure that any magnetic field disturbances are prevented. The support is then bonded to a support structure (not shown) on which is mounted a counterweight load for receiving a given power.

The primary coil 82 is configured by an annular winding of the magnetic wire 96 wound on the insulating bobbin 98. Although the winding of FIG. 4 is a single annular coil, it may be located within the cavity 88 of several individual coils connected in series.

The secondary coil 84 is another annular winding made of the magnetic wire 100 on the bobbin 102. The bobbin 102 is also made of an insulating material such as phenol resin. The coil 84 is provided with a mechanical clearance 104 in the vertical direction and a clearance 106 in the horizontal direction, and as a result, it is distributed so as to obtain a desired degree of freedom of movement in the axial direction, the radial direction and the angular direction. The mechanical clearance is preferably much larger than the desired area of motion of the secondary coil 84 to minimize the effects of magnetic disturbing forces on the support structure associated with the coil.
Typically, the transformer according to the present invention provides 0.05 to 0.50 inch of free movement over six degrees of freedom. Although the support 94 is shown extending through the end plate 90, the openings could alternatively be provided in the magnetic core, i.e. at the base of the sidewalls, with appropriate clearance for the primary coil.

In the preferred embodiment where the excitation current is provided at an audio frequency of about 10 kHz, 525 parallel strands of 33 # AWG insulated copper wire in the well-known Ritz wire format are wound seven times to reduce skin effect. An electromagnetic coupling device is configured by a transformer having a primary coil and a secondary coil formed by winding a total of 1750 strands of the 33 # AWG ridge wire wound twice. The magnetic core is made of a manganese-zinc ferrite material and has flat upper and lower plates,
The inner and outer rings are used to form the magnetic core. The coil bobbin is finished with a cloth reinforced phenolic resin having a wall thickness of 0.075 inches (where 1 inch is 2.54 centimeters) to 0.125 inches. The conductors of the transformer are terminated with brass lugs 6 inches from the body of the transformer and act as an electrical interface to the input and output circuits.

The above model, which was designed for a 2500 Watt power transformer, exhibits a power output that is almost independent of the displacement of the platform with a power transfer efficiency of 99.3%. The disturbance force of the secondary coil is approximately 0.006 lbs / foot in the axial direction (where 1 lb is 453 grams and 1 foot is 3
0.48 cm), which is 0.003 lb / foot or less in the radial direction. Exercise capacity ± ± in the radial direction
It is 0.20, the inclination is ± 0.75 °, and the rotation is ± 2 °.

FIG. 5 shows a magnetic suspension movable base for a precision instruction mounting portion provided with an electromagnetic coupling device 112 according to the present invention.
The ring-shaped magnetic core 114 has a ring-shaped chamber that is connected to the mounting portion, and a primary winding 116 that is biased by a power source (not shown) is fixedly mounted in the ring-shaped chamber. ing. The movable secondary winding 117 is sealed in the magnetic core and is attached to the base 110 via a non-magnetic support 118. The secondary windings are coupled to bias a compensating load (not shown) such as an optical machine or antenna attached to the pedestal 110, thus making use of slip rings or flexible cables. Can be avoided. The data signal of the replacement load is sent through the axial bore of the transformer via an optical coupling device (not shown) housed in an axial container 122 in the mount.
The transformer can be integrated with the optical coupling device by way of a hole, since it has to be operated at the centerline of rotation. The closed magnetic core 114 allows the transformer to be positioned in close contact with the magnetic bearing assemblies 124 and 126 without causing unwanted disturbances due to leakage flux therebetween.

The pedestal 110 is magnetically supported and oriented to provide six degrees of freedom by magnetic bearing assemblies 124 and 126 cooperating with armatures 128 and 130 supporting the pedestal, respectively. Since the required motion region is limited, the clearance between the secondary coil and the primary winding of the magnetic core is sufficiently large, and the primary winding is biased by the force-displacement characteristic which is a displacement function. As a result of extracting energy from the secondary winding, the mechanical force exerted on the carriage is significantly reduced.

Referring again to FIG. 4, in operation, the winding 82 is AC
It is energized by a power source and produces a magnetic flux that alternates. Since the magnetic path is substantially contained in the magnetic core 80 and completely surrounds the secondary winding 84, the primary winding 8 of the secondary winding 84 is
An electromagnetic voltage is applied to the secondary winding 84 regardless of the physical displacement with respect to 2. In all of the magnetic core materials, since the secondary coil remains fixed during the movement, no interaction by magnetic force occurs between the magnetically permeable surfaces. Therefore, the operational limitation of the secondary winding is substantially weakened. The secondary coil 84 is free to move within the mechanical clearances 104, 106 without significantly changing the energy conversion efficiency. Contrary to prior art devices utilizing a magnetic circuit with an air gear for free rotation of one of the magnetic components, the present invention uses a magnetic circuit without any air gear. As a result, leakage flux is limited and electromagnetic disturbance is minimized. Further, since the movable part of the transformer does not include any magnetically permeable body, it is hardly affected by a disturbance force.

While this invention has been described in its preferred embodiment, the terminology used is not limiting and is intended to be broad in its broader scope and beyond the true scope and spirit of the invention. It is to be understood that modifications can be made without departing from the scope of the appended claims.

[Brief description of drawings]

FIG. 1A is a sectional view of an ordinary fixed transformer, and FIG.
FIG. 1 is a sectional view of a rotating transformer having a rotatable magnetic core and a secondary winding, and FIG. 1C is a sectional view of a rotating transformer having a fixed magnetic core and a rotatable secondary winding. FIG. 1D is a cross-sectional view of a device according to the present invention showing a fixed magnetic core and a movable secondary winding, and FIG. 2 is a cross-sectional perspective view of the magnetic core and coil structure according to the present invention. FIG. 4 is a plan view of the present invention, FIG. 4 is a cross-sectional view of the present invention taken along line 4-4 of FIG. 3, and FIG. 5 has an electromagnetic coupling device such as the present invention. FIG. 6 is a partially cutaway conceptual perspective view of a magnetic suspension system and FIG. 6 is a cross-sectional view of a leakage flux pattern useful in understanding the present invention. In the figure, 36 is a magnetic core, 38 is an annular pot-shaped housing, 40
Is a cover plate, 42 is an interface, 44 is a primary coil, 46 is a secondary coil, 48 and 50 are support structural members, 52 is a clearance hole, 60 is a closed magnetic core, 6
2 is a magnetically permeable annular ring, 64 is a cavity, 66 is a cover plate, 68 is a first electric winding, 70 is a second electric winding, 7
2 is a structural support, 74 is an opening, 80 is a magnetically permeable magnetic core, 82
Is a primary coil, 84 is a secondary coil, 86 is a pot core,
Reference numeral 88 is an annular cavity, 90 is an end plate, 92 is an opening, 94 is a support, 96 and 100 are annular windings, 98 and 102 are insulating bobbins, 104 and 106 are mechanical clearances, 110 is a base, and 112 is electromagnetic. Coupling device, 114 is an annular magnetic core, 115 is a precision indicating attachment part, and 124 and 126.
Are magnetic bearing assemblies, 128 and 130 are armatures,
Are shown respectively.

Claims (14)

[Claims] 1. In a non-contact power transformer, the device is a closed magnetic core made of a magnetic body having substantially no air gear, and performs relative movement between first and second electric windings positioned therein. A magnetic core defining a cavity adapted to move, the first electric winding fixed to the magnetic core and placed in the cavity, and arranged radially with respect to the first winding. A second magnetic flux coupling member that is positioned to move in the cavity and maintains a substantially constant magnetic flux coupling with the first winding regardless of a positional relationship with respect to the first winding and the magnetic core. The non-contact power transformer, which is configured by an electric winding. 2. The device according to claim 1, wherein the second winding is further constituted by at least one non-magnetic support member attached thereto, and the magnetic core is provided with the support. A non-contact power transformer as claimed in claim 1 which is provided with at least one corresponding opening for accommodating a member and which provides a limited relative angular and linear movement between the first and second windings. 3. The non-contact power transformer according to claim 2, wherein the magnetic core is constituted by a main body having a substantially cylindrical cross-sectional area. 4. The apparatus according to claim 3, wherein the magnetic core is made of ferrite material and has an interface with an engaging cover plate having almost no air gears, and the cavity has the first cover. A non-contact power transformer as defined in claim 1, which defines an annular pot shape for accommodating the first and second windings and wherein the opening is in the cover plate and aligned with the support member. 5. The apparatus of claim 4, wherein the first winding is adapted to connect to a source of electrical energy and the second winding is at least a portion of the electrical energy. The non-contact power transformer is characterized in that it is designed to give a load to a load. 6. The device according to claim 5, wherein the first and second windings are a plurality of parallel conductors having a predetermined diameter, and when they are moved at an audible frequency, a skin effect is produced. The non-contact power transformer according to claim 1, wherein the non-contact power transformer is configured by the conductor configured to minimize 7. The apparatus according to claim 6, wherein the first and second windings are respectively wound on a non-conductive, non-metal, non-magnetic bobbin, and the second winding is provided. The non-contact power transformer, wherein the winding is concentrically arranged in the first winding. 8. The apparatus according to claim 7, wherein the magnetic core is attached to a support base, and the support member of the second winding is connected to a structure supporting a movable member. The non-contact power transformer described above. 9. The non-contact power transformer as claimed in claim 8, wherein the support structure is constituted by a magnetically actuated suspension device. 10. The non-contact power transformer according to claim 2, wherein the linear movement is limited to a predetermined linear displacement. 11. The apparatus according to claim 10, wherein the second coil is provided with a predetermined clearance with respect to the first coil that exceeds the predetermined linear displacement, and the displacement is The non-contact power transformer, wherein the non-contact power transformer is in a substantially uniform leakage magnetic flux region. 12. The non-contact power transformer according to claim 2, wherein the angular movement is limited to a predetermined angular displacement. 13. The apparatus according to claim 2, wherein the second coil is provided with another predetermined clearance with respect to the first coil which exceeds the predetermined angular displacement, and The non-contact power transformer, wherein the angular displacement is in a substantially uniform leakage flux region. 14. A magnetically actuated suspension of the type having a movable base for supporting a device to be electrically biased and an opening in the movable base for applying a control signal to a fixed support. In the device, the electromagnetic coupling device defines a flux path substantially free of air gears, having a through-hole through which the control signal is transmitted and defining an annular chamber for containing the first and second electrical windings. An annular closed magnetic core made of a magnetic body, the first electric winding fixedly positioned to the magnetic core, and at least a part of the first winding positioned in the radial direction, and the magnetic core and the first magnetic winding are positioned. Mounted on the second coil, the second electric winding having a predetermined clearance between the windings and arranged for limited movement in a plurality of directions in a substantially uniform leakage flux region; First end and front Energizing at least one non-magnetic support member having a second end fixed to the movable base, the magnetic core having an opening for accommodating the support member, and the first winding. The energy provided therefrom is extracted from the second winding and exceeds the limited movement so as to exhibit a force-displacement characteristic of a predetermined value or less with respect to the mechanical force given to the movable table. The non-contact power transformer, wherein the non-contact power transformer is configured by the predetermined clearance distributed accordingly.