FR2579386A1 - Electrostatic method and capacitive devices for transforming an AC voltage - Google Patents

Abstract

The invention relates to a method and capacitive devices for transforming an AC voltage. A device according to the invention includes a primary capacitor whose plates 1a, 1b are separated by D. A primary voltage V is applied between these plates. It includes one or more secondary capacitors whose plates 2a, 2b are a length d < D apart and are placed between the plates 1a, 1b of the primary capacitor. A secondary voltage v, which is always proportional to the latter voltage, is gathered at the terminals C, D connected to the plates of the secondary capacitor. One application is the construction of impedance-matching or coupling transformers in electronic circuits.

Description

 The present invention relates to an electrostatic process and capacitive devices for transforming an alternating voltage.

 The technical sector of the invention is that of electrical and electrostatic constructions.

 Known transformers are inductive devices in which an alternating current which flows in a primary winding creates an alternating magnetic field which induces a voltage in a secondary winding. These transformers require magnetic circuits in sheet metal which are heavy, bulky and expensive.

 The object of the present invention is to provide alternating current transformers which no longer use a magnetic field, but an electric field to transfer electrical power between a primary circuit and one or more secondary circuits, so that the the need for a magnetic circuit is avoided, which makes it possible to build lighter, less bulky and less expensive transformers.

 This objective is achieved by a method for transforming an alternating voltage, according to which an electric field is created by applying said voltage to the armatures of a primary capacitor, one or more secondary capacitors are placed in said electric field between the armatures of said primary capacitor and an alternating voltage whose amplitude is proportional to that of said primary voltage is collected between the plates of said secondary capacitors.

 A device according to the invention comprises a primary capacitor on the plates of which said alternating voltage is applied and one or more secondary capacitors, the two plates of which are placed between the plates of said primary capacitor and which deliver a secondary voltage.

 According to a first embodiment, a device according to the invention comprises a flat primary capacitor composed of two planar armatures and of two planar solid dielectric layers placed against the internal faces of said armatures and separated by an intermediate space and it further comprises a or several planar secondary capacitors composed of two armatures and a solid dielectric which are placed in said intermediate space.

 According to another embodiment, a device according to the invention comprises a wound primary capacitor which is composed of two wound armatures and of dielectric layers which separate said armatures and it further comprises at least two secondary capacitors which are each constituted by a pair of wound armatures, separated by a dielectric, each pair of armatures being disposed in the interval between two dielectric layers wound in each space separating the two armatures of the capacitor.

 The invention results in new electrostatic transformers which make it possible to transform an alternating voltage into another alternating voltage, of the same frequency and of amplitude lower or higher than that of the primary voltage.

 At equal power, a transformer according to the invention is lighter, less bulky and less expensive to build than a traditional magnetic induction transformer.

 The transformers according to the invention are particularly well suited to serve as transformers for electrostatic coupling between the stages of a radio or television receiver or of an electro-acoustic circuit or as transformer adapters of impedance.

 The transformers according to the invention can be used as autotransformers, an armature then being common to primary and secondary.

 The following description refers to the appended drawings which represent, without any limiting character, exemplary embodiments of devices according to the invention.

 Figure 1 is a schematic representation of an electrostatic transformer according to the invention.

 Figure 2 is a cross section of a flat transformer according to the invention.

 Figure 3 is a section perpendicular to the axis of a wound transformer according to the invention.

 FIG. I represents the two armatures la and lb of a capacitor called primary capacitor between which an alternating voltage is applied V. D is the distance between the two armatures la and lb.

A uniform electric field Eperpendicular to the armatures - + v exists between the two armatures and lton knows that E =
There is between the plates la and lb, one or more capacitors whose plates 2a and 2b are spaced from d, d being less than D.

I1 appears between the two terminals C and D connected to the mature ar 2a and 2b, an alternative tension v such that v mature 2a and 2b, an alternating voltage v, such that -E
We thus obtain a secondary voltage I vD = dfVI that is
d say a voltage whose amplitude is reduced in the ratio
Several secondary capacitors can be placed between the plates of a primary capacitor. The secondary capacitors can be connected in parallel or in series, so that the amplitude of the secondary voltage can be lower or higher than that of the primary voltage.

 The power of the transformer is proportional to the capacity of the primary and to the respective capacities of the secondary capacitors.

FIG. 2 represents, in cross section, a first embodiment of an electrostatic transformer according to the invention. This comprises a flat primary capacitor composed of two flat armatures 3a and 3b which are connected respectively to two terminals A and B, between which an alternating voltage is applied
V. The primary capacitor comprises a dielectric composed of two flat solid layers 4a and 4b which are placed against the internal faces of the armatures and which are separated by an intermediate space 5. In this space are arranged one or more secondary secondary capacitors each composed of two plates 6a, 6b and 7a, 7b respectively and a solid dielectric, respectively 6c and 7c.

 FIG. 2 represents an example of a transformer comprising two secondary capacitors connected in series by connecting a frame of one to the frame of opposite polarity of the other by a conductor which connects for example the frame 6a to the reinforcement 7b.

 This conductor is located outside the space between the frames 4a and 4b. The output terminals C and D of the secondary are connected respectively to the frames 7a and 6b.

 FIG. 3 represents a transformer according to the invention which is constituted by wound type capacitors.

 For clarity of the drawing, the armatures 8a and 8b of the primary capacitor are shown in solid lines between which a primary voltage V is applied.

 The lines 9a and 9b of a first secondary capacitor which are placed between the plates 8a and 8b starting from the center and the plates IOa and lOb of a second secondary capacitor which are placed between the plate 8b leaving are shown in dotted lines. from the center and the second turn of frame 8a. In this embodiment, the secondary circuit necessarily includes an even number of capacitors which can be coupled in series or in parallel.

 For clarity of the drawing, the dielectrics have not been shown in FIG. 3.

 In the two embodiments, the usual dielectrics are used in the technology for constructing alternating current capacitors, that is to say non-polar dielectrics.

Claims (4)

 1. Electrostatic method for transforming an alternating voltage, characterized in that an electric field is created by applying said voltage to the plates of a primary capacitor, one or more secondary capacitors are placed in said electric field between the plates of said primary capacitor and an alternating voltage whose amplitude is proportional to that of said primary voltage is collected between the plates of said secondary capacitors.  2. Device for transforming an alternating voltage (V-) characterized in that it comprises a primary capacitor on the armatures (la, lb) from which said alternating voltage (V-) is applied and one or more secondary capacitors including the two armatures ( 2a, 2b) are placed between the armatures of said primary capacitor and which deliver a secondary voltage (v).  3. Device according to claim 2, characterized in that it comprises a flat primary capacitor composed of two flat reinforcements (3a, 3b) and two flat solid dielectric layers (4a, 4b) placed against the internal faces of said reinforcements and separated by an intermediate space (5) and it further comprises one or more planar secondary capacitors composed of two armatures (6a, 6b, 7a, 7b) and a solid dielectric (6c, 7c) which are placed in said space intermediate.  4. Device according to claim 2, characterized in that it comprises a wound primary capacitor which is composed of two wound armatures (8a, 8b) and of dielectric layers which separate said armatures and it comprises> in addition, at least two capacitors secondary which are each constituted by a pair of wound armatures (9a, 9b, ioda, lOb), separated by a dielectric, each pair of armatures being arranged in the interval between two dielectric layers wound in each space separating the two armatures of the primary capacitor.