News Column

Patent Issued for Resonant Transformer and Resonant Converter Employing Same

February 26, 2014



By a News Reporter-Staff News Editor at Electronics Newsweekly -- A patent by the inventors Tsai, Hsin-Wei (Taoyuan Hsien, TW); Chang, Shih-Hsien (Taoyuan Hsien, TW); Tien, Ching-Hsing (Taoyuan Hsien, TW), filed on January 11, 2012, was published online on February 11, 2014, according to news reporting originating from Alexandria, Virginia, by VerticalNews correspondents.

Patent number 8648686 is assigned to Delta Electronics, Inc. (Taoyuan Hsien, TW).

The following quote was obtained by the news editors from the background information supplied by the inventors: "A transformer has become an essential electronic component for voltage regulation into required voltages for various kinds of electric appliances.

"In the power supply system of the new-generation electric products such as LCD televisions, leakage inductance transformers (e.g. LLC transformers) become more and more prevailing. The use of the leakage inductance transformer may reduce damage possibility of the switch, minimize noise and enhance performance.

"FIG. 1 is a schematic exploded view of a conventional leakage inductance transformer. As shown in FIG. 1, the transformer 1 comprises a bobbin 11, a covering member 12, and a magnetic core assembly 13. A primary winding coil 111 and a secondary winding coil 112 are wound around the bobbin 11. The output terminals 113, 114 of the primary and the secondary winding coils 111, 112 are directly wound and soldered on pins 115, which are perpendicularly extended from the bottom of the bobbin 11. The covering member 12 is used for partially sheltering the upper portion of the bobbin 11 in order to increase the creepage distances between the primary winding coil 111, the secondary winding coil 112 and the magnetic core assembly 13. The magnetic core assembly 13 includes middle portions 131 and leg portions 132. The middle portions 131 are accommodated within a channel 116 of the bobbin 11. The bobbin 11 is partially enclosed by the leg portions 132. Meanwhile, the transformer 1 is assembled.

"Please refer to FIG. 1 again. After the covering member 12 is placed over the bobbin 11 to shelter the bobbin 11, the creepage distances between the primary winding coil 111, the secondary winding coil 112 and the magnetic core assembly 13 are increased. The use of the covering member 12, however, increases the overall height of the transformer 1. In addition, the required inductance is determined according to the turn numbers of the primary winding coil 111 and the secondary winding coil 112. If the diameter of the primary winding coil 111 or the secondary winding coil 112 is too large, the overall volume of the transformer 1 is increased as the turn numbers are increased. That is, it is difficult to minimize the conventional transformer 1.

"In addition, after the transformer 1 is assembled, an air gap (not shown) is defined between the corresponding leg portions 132. The air gap is formed between the primary winding coil 111 and a secondary winding coil 112. If the secondary winding coil 112 is in a short-circuit condition, the magnetic path possibly causes individual loop. Under this circumstance, the leakage inductance of the transformer 1 fails to be stably controlled.

"Due to that the bobbin 11 of the transformer 1 has only one single-trough first winding section for winding one primary winding coil 111 and one single-trough second winding section for winding one secondary winding coil 112, and the bobbin 11 has limited space for winding coils, and the turn numbers of the primary winding coil 111 and the secondary winding coil 112 are also limited. Therefore, the transformer 1 has a limited maximum power output of 100 Watts. When a power converter having a relatively high power output of 400 Watts is designed, four transformers 1 connected in series or in parallel must be employed in the power converter. It is obvious that the manufacturing cost of the power converter will be increased due to the usage of four set of bobbins 11 and four set of magnetic core assemblies 13 of the four transformers 1."

In addition to the background information obtained for this patent, VerticalNews journalists also obtained the inventors' summary information for this patent: "It is an object of the present invention to provide a resonant transformer and a resonant converter employing the same. The resonant transformer has plural single-trough second winding sections. Plural secondary winding coils are wound around respective single-trough second winding sections, so that the winding means and the magnetic path are changed and the manufacturing cost of the power converter having 4 times power output is reduced.

"Another object of the present invention provides a resonant transformer and a resonant converter employing the same. The resonant transformer has an air gap disposed over the primary winding coil, thereby stably controlling the leakage inductance.

"A further object of the present invention provides a resonant transformer and a resonant converter employing the same. The resonant transformer has increased winding space, enhanced electric conversion efficiency, and reduced heat generation.

"A still object of the present invention provides a resonant transformer and a resonant converter employing the same. The resonant transformer has plural modular bobbins connected with each other in parallel, so that the output voltage of the resonant transformer is increased.

"In accordance with an aspect of the present invention, there is provided a resonant transformer. The resonant transformer includes a first bobbin, a first primary winding coil, plural first secondary winding coils, a second bobbin, a second primary winding coil, plural second secondary winding coils, and a magnetic core assembly. The first bobbin includes a first main body and a first channel running through the first main body. The first main body includes a first winding section and plural single-trough second winding sections. Plural pins are arranged at the first winding section. The single-trough second winding sections are arranged at bilateral sides of the first winding section. The first primary winding coil is wound around the first winding section of the first bobbin, and connected with the pins at the first winding section. The first secondary winding coils are wound around respective single-trough second winding sections of the first bobbin. The second bobbin includes a second main body and a second channel running through the second main body. The second main body includes a third winding section and plural single-trough fourth winding sections. The single-trough fourth winding sections are arranged at bilateral sides of the third winding section. The second primary winding coil are wound around the third winding section of the second bobbin, and connected with the pins at the first winding section of the first bobbin. The second secondary winding coils are wound around respective single-trough fourth winding sections of the second bobbin. The magnetic core assembly is partially embedded into the first channel of the first bobbin and the second channel of the second bobbin.

"In accordance with another aspect of the present invention, there is provided a resonant converter for converting an input voltage into an output voltage to drive a DC load. The resonant converter includes a switch circuit, a resonant circuit, a resonant transformer, a rectifier and a filter. The switch circuit is configured to receive the input voltage. The resonant circuit is connected with the switch circuit. The resonant transformer has an input winding connected with the resonant circuit and a plurality of output windings. The resonant transformer is configured to transfer the energy of the input voltage from the input winding to the output windings by a switching operation of the switch circuit and a resonance produced by the resonant circuit. The rectifier is connected with the output windings. The filter is connected with the rectifier for filtration so as to output the output voltage. The resonant transformer includes a first bobbin, a first primary winding coil, plural first secondary winding coils, a second bobbin, a second primary winding coil, plural second secondary winding coils, and a magnetic core assembly. The first bobbin includes a first main body and a first channel running through the first main body. The first main body includes a first winding section and plural single-trough second winding sections. Plural pins are arranged at the first winding section. The single-trough second winding sections are arranged at bilateral sides of the first winding section. The first primary winding coil is wound around the first winding section of the first bobbin, and connected with the pins at the first winding section. The first secondary winding coils are wound around respective single-trough second winding sections of the first bobbin. The second bobbin includes a second main body and a second channel running through the second main body. The second main body includes a third winding section and plural single-trough fourth winding sections. The single-trough fourth winding sections are arranged at bilateral sides of the third winding section. The second primary winding coil are wound around the third winding section of the second bobbin, and connected with the pins at the first winding section of the first bobbin so as to form the input winding. The second secondary winding coils are wound around respective single-trough fourth winding sections of the second bobbin and connected with the first secondary winding coils so as to form the output windings. The magnetic core assembly is partially embedded into the first channel of the first bobbin and the second channel of the second bobbin.

"In accordance with another aspect of the present invention, there is provided a resonant transformer. The resonant transformer includes a bobbin, a primary winding coil, plural secondary winding coils, a covering member, and a magnetic core assembly. The bobbin includes a main body and a first channel running through the main body. The main body includes a first winding section and plural single-trough second winding sections. Plural pins are arranged at the first winding section. The single-trough second winding sections are arranged at bilateral sides of the first winding section. The primary winding coil is wound around the first winding section of the bobbin and connected with the pins. The secondary winding coils are wound around respective single-trough second winding sections of the bobbin. The covering member includes a second channel. The magnetic core assembly is partially embedded into the first channel of the bobbin and the second channel of the covering member.

"The above contents of the present invention will become more readily apparent to those ordinarily skilled in the art after reviewing the following detailed description and accompanying drawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS

"FIG. 1 is a schematic exploded view of a conventional transformer;

"FIG. 2 is a schematic exploded view illustrating a resonant transformer according to a first embodiment of the present invention;

"FIG. 3A is a schematic exploded view illustrating a resonant transformer according to a second embodiment of the present invention;

"FIG. 3B is a schematic assembled view illustrating the resonant transformer of FIG. 3A;

"FIG. 4A is a schematic exploded view illustrating a resonant transformer according to a third embodiment of the present invention;

"FIG. 4B is a schematic assembled view illustrating the resonant transformer of FIG. 4A; and

"FIG. 5 shows the circuitry of the resonant converter employing the resonant transformer shown in FIG. 4A."

URL and more information on this patent, see: Tsai, Hsin-Wei; Chang, Shih-Hsien; Tien, Ching-Hsing. Resonant Transformer and Resonant Converter Employing Same. U.S. Patent Number 8648686, filed January 11, 2012, and published online on February 11, 2014. Patent URL: http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&p=49&u=%2Fnetahtml%2FPTO%2Fsearch-bool.html&r=2405&f=G&l=50&co1=AND&d=PTXT&s1=20140211.PD.&OS=ISD/20140211&RS=ISD/20140211

Keywords for this news article include: Delta Electronics Inc.

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Source: Electronics Newsweekly


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