WO2024103396A1

WO2024103396A1 - Power converter and method for manufacturing the same

Info

Publication number: WO2024103396A1
Application number: PCT/CN2022/132912
Authority: WO
Inventors: Yulin Chen; Yanbo Zou; Wenjie LIN; Shangui OU
Original assignee: Innoscience (Shenzhen) Semiconductor Co., Ltd.
Priority date: 2022-11-18
Filing date: 2022-11-18
Publication date: 2024-05-23

Abstract

The present disclosure provides a power converter (100) and a method for manufacturing a GaN based power converter. The power converter includes an input port (110), an output port (120), a planar transformer (130, 230), a primary switch (Q 1), and a synchronous rectifier (Q 2). The planar transformer includes a U-shaped magnetic core (232), a first primary coil winding (NP1), a second primary coil winding (NP2) electrically connected in series with the first primary coil winding, a first secondary coil winding (NS1), and a second secondary coil winding (NS2) electrically connected in parallel to the first secondary coil winding. The U-shaped magnetic core includes a first core projection (2321) and a second core projection (2322). The first and second primary coil windings are configured to surround the first and second core projections respectively. The first and second secondary coil windings are configured to surround the first and second core projections respectively.

Description

POWER CONVERTER AND METHOD FOR MANUFACTURING THE SAME

Field of the Invention:

The present invention generally relates to a power converter, and more specifically, the present invention relates to an energy and cost-efficient GaN-based power converter.

Background of the Invention:

Power converters are inevitable devices that are used to power many household and industrial machines by providing a direct current (DC) power source that has been rectified from an alternating current (AC) power source provided by an AC source. Typically, a flyback transformer in the power converter for fast charging adopts E-shaped magnetic core. The transformer includes a primary coil winding, a secondary coil winding, and an auxiliary coil winding are wound in layers along the central column.

Several architectures have been proposed to develop the cost and energy efficient power converter. The typical transformer in the flyback converter uses high turns ratio (e.g., 14: 2) . When the transformer window area is limited, considering current density of the coil, the primary coil winding needs to be wound on two layers of the PCB. Similarly, the secondary coil winding needs to be wound on two layers of the PCB. In order to avoid EMI, two layers of the shield windings are required. Therefore, six layers of PCB is required for the transformer design in the power converter, eventually increasing the manufacturing cost of transformer and an effective current in the transformer.

Along with the requirement of an energy and cost-efficient power converter, it could be desirable to develop an area and energy efficient transformer in the power converter for certain applications in the field.

Summary of the Invention:

The power converter of the invention includes an input port, an output port, a planar transformer, a primary switch, and a synchronous rectifier. The input port having a low-potential terminal and a high-potential terminal. The output port having a low-potential terminal and a high-potential terminal. The planar transformer including a U-shaped magnetic core, a first primary coil winding, a second primary coil winding electrically connected in series with the first primary coil winding, a first secondary coil winding, and a second secondary coil winding electrically connected in parallel to the first secondary coil winding. The primary switch having a first conduction terminal electrically coupled to the second primary coil winding and a second conduction terminal electrically coupled to the low-potential terminal of the input port. The synchronous rectifier having a first conduction terminal electrically coupled to the first secondary coil windings and a second conduction terminal electrically coupled to a high-potential terminal of the output port. The U-shaped magnetic core includes a first core projection and a second core projection. The first and second primary coil windings are configured to surround the first and second core projections respectively. The first and second secondary coil windings are configured to surround the first and second core projections respectively.

Based on the above transformer design, the transformer PCB can be reduced from six layers to four layers, which effectively reduces the cost of the transformer. In addition, the four-layer-structured of transformer PCB is sufficient to solve the EMI and safety problem in the power converter. Moreover, by electrically connecting the first secondary coil winding and the second secondary coil winding in parallel, the effective value of the current flowing through the first secondary coil winding and the second secondary coil winding is reduced to half, which eventually reduces the copper loss of the transformer to half. Therefore, an energy and cost-efficient power converter is achieved.

Brief Description of the Drawings:

Aspects of the present disclosure may be readily understood from the following detailed description with reference to the accompanying figures. The illustrations may not necessarily be drawn to scale. That is, the dimensions of the various features may be arbitrarily increased or reduced for clarity of discussion. There may be distinctions between the artistic renditions in the present disclosure and the actual apparatus due to manufacturing processes and tolerances. Common reference numerals may be used throughout the drawings and the detailed description to indicate the same or similar components.

FIG. 1 illustrates a circuit diagram of a power converter according to an exemplary embodiment of the disclosure.

FIGS. 2A and 2B are cross-section view and top view of an exemplary structure for a transformer according one embodiment of the present invention; and FIG. 2C is the isometric view of the magnetic core used in the transformer.

FIG. 3 illustrates a flowchart of a method for manufacturing a GaN based power converter according to an exemplary embodiment of the disclosure.

FIG. 4 illustrates a flowchart of a method for constructing a planar transformer according to an exemplary embodiment of the disclosure

Detailed Description:

In the following description, preferred examples of the present disclosure will be set forth as embodiments which are to be regarded as illustrative rather than restrictive. Specific details may be omitted so as not to obscure the present disclosure; however, the disclosure is written to enable one skilled in the art to practice the teachings herein without undue experimentation.

It is to be understood that other embodiment may be utilized and structural changes may be made without departing from the scope of the present invention. Also, it is to be understood that the phraseology and terminology used herein are for the purpose of description and should not be regarded as limiting. The use of “including, ” “comprising, ” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless limited otherwise, the terms “connected, ” “coupled, ” and “mounted, ” and variations thereof herein are used broadly and encompass direct and indirect connections, couplings, and mountings.

FIG. 1 illustrates a circuit diagram of a power converter according to an exemplary embodiment of the disclosure. Referring to FIG. 1, the power converter 100 includes an input port 110, an output port 120, a transformer 130, a switch Q1, and a synchronous rectifier Q2.

The power converter 100 is a flyback converter.

In one embodiment, the power converter 100 is GaN based power converter.

The input port 110 having a low-potential terminal and a high-potential terminal. The low-potential terminal is a ground terminal and the high-potential terminal is an input terminal Vin. The input port 110 includes an input capacitor C1.

The input capacitor C1 includes a first terminal and a second terminal. The first terminal of the input capacitor C1 is electrically coupled to the input terminal Vin. The second terminal of the input capacitor C1 is electrically coupled to the ground terminal. The input capacitor C1 is chosen in a way to minimize ripples in the input voltage.

The output port 120 having a low-potential terminal and a high-potential terminal. The low-potential terminal is the ground terminal, and the high potential terminal is an output terminal Vout. The output port 120 includes an output capacitor C2.

The output capacitor C2 includes a first terminal and a second terminal. The first terminal of the output capacitor C2 is electrically coupled to the output terminal Vout. The second terminal of the output capacitor C2 is electrically coupled to the ground terminal. The output capacitor C2 is chosen in the way to optimize transient load response and loop stability.

The transformer 130 is a planer transformer. The transformer 130 includes a U-shaped magnetic core, a first primary coil winding NP1, a second primary coil winding NP2, a first secondary coil winding NS1, a second secondary coil winding NS2, and an auxiliary coil winding NA.The transformer 130 may further include shield coil windings (not shown in FIG. 1) .

The U-shaped magnetic core includes a first primary magnetic column, a second primary magnetic column, a first secondary magnetic column, and a second secondary magnetic column.

The first primary coil winding NP1 is electrically connected in series with the second coil winding NP2.

The first secondary coil winding NS1 is electrically connected in parallel to the second secondary coil winding NS2.

The first primary coil winding NP1 and the second primary coil winding NP2 are respectively wounded on a first primary magnetic column and a second primary magnetic column.

The number of turns of the first primary coil winding NP1 is equal to number of turns of the second primary coil winding NP2.

The first primary coil winding NP1 is wound on the first primary magnetic column in a direction opposite to the direction of the second primary coil winding NP2 wound on the second primary magnetic column. To be specific, the first primary coil winding NP1 is wound on the first primary magnetic column in a first direction and the second primary coil winding NP2 is wound on the second primary magnetic column in a second direction. The first direction is 180 degrees shift to the second direction.

Similarly, the first secondary coil winding NS1 and the second secondary coil winding NS2 are respectively wounded on a first secondary magnetic column and a second secondary magnetic column.

The number of turns of the first secondary coil winding NS1 is equal to number of turns of the second secondary coil winding NS2.

The first secondary coil winding NS1 is wound on the first secondary magnetic column a same direction as the direction of the second secondary coil winding NS2 wound on the second secondary magnetic column. To be specific, the first secondary coil winding NS1 is wound on the first secondary magnetic column and the second secondary coil winding NS2 is wound on the second secondary magnetic column in a first direction.

The power converter 100 further includes a diode D1 and an auxiliary coupling capacitor C3. The diode D1 having an anode electrically coupled to a first terminal of the auxiliary coil winding NA. The auxiliary coupling capacitor C3 having a first end electrically coupled to a cathode of the diode D1 and a second end electrically coupled to a second terminal of the auxiliary coil winding NA.

The primary switch Q1 having a first conduction terminal electrically coupled to the second primary coil winding and a second conduction terminal electrically coupled to the low-potential terminal of the input port 110.

The synchronous rectifier (Q2) having a first conduction terminal electrically coupled to the first secondary coil winding and a second conduction terminal electrically coupled to a high-potential terminal of the output port.

The type of the primary switch Q1 and the synchronous rectifier Q2 are not limited in this disclosure. In one embodiment, the primary switch Q1 and the synchronous rectifier Q2 are GaN switching devices. In some embodiments, the primary switch Q1 and the synchronous rectifier Q2 are GaN/AlGaN high-electron-mobility transistors (HEMTs) .

In some embodiments, the primary switch Q1 and the synchronous rectifier Q2 are metal insulator semiconductor field effect transistors.

FIGS. 2A and 2B are cross-section view and top view of an exemplary structure for a transformer 230 according one embodiment of the present invention; and FIG. 2C is the isometric view of the magnetic core used in the transformer.

Referring to FIG. 2A, the transformer 230 is formed in a four-layered printed circuit board (PCB) 231.

With reference to FIGS. 1 and 2A to 2C, the first primary coil winding NP1, and the second primary coil winding NP2 are formed on a primary coil layer L1 of the PCB 231.

The first secondary coil winding NS1, and the second secondary coil winding NS2 are formed on a secondary coil layer L2 of the PCB 231.

The auxiliary coil winding NA is formed on an auxiliary coil layer L11 of the PCB which is disposed between the primary coil layer L1 and the secondary coil layer L2 of the PCB 231.

Optionally, the transformer 130 further includes a first shield coil winding NSH1, a second shield coil winding NSH2, a third shield coil winding NSH3, and a fourth shield coil winding NSH4.

In one embodiment, the first shield coil winding NSH1 may be formed on the auxiliary coil layer L11 of the PCB 231. The second shield coil winding NSH2 may be formed on the auxiliary coil layer L11 of the PCB 231. The third shield coil winding NSH3 and the fourth shield coil winding NSH4 are being formed on a shielding coil layer L22 of the PCB 231.

The auxiliary coil layer L11 of the PCB 231 is adjacent to the primary coil layer L1 of the PCB 231. The auxiliary coil layer L22 of the PCB 231 is adjacent to the secondary coil layer L2 of the PCB 231.

In other words, the top layer L1 of the PCB 231 includes the first primary coil layer NP1 and the second primary coil layer NP2. The second layer L11 of the PCB 231 includes the first shield coil winding NSH1, the second shield coil layer NSH2, and auxiliary coil layer NA. The third layer L2 of the PCB 231 includes the first secondary coil winding NS1 and the second secondary coil winding NS2. The fourth layer L22 of the PCB 231 includes the third shield coil winding NSH3 and the fourth shield coil layer NSH4.

With reference to FIG. 2B and FIG. 2C, the transformer 230 includes a U-shaped magnetic core 232 having a first core projection 2321 and a second core projection 2322.

In one embodiment, the first primary windings NP1, first secondary winding NS1, shield coil winding NSH1 and third shield coil winding NSH3 are wound on the first core projection 2321. The second primary windings NP2, second secondary winding NS2, second shield coil winding NSH2 and fourth shield coil winding NSH4 are wound on the second core projection 2322.

The auxiliary coil winding NA may be wounded on one of a first core projection 2321 and a second core projection 2321.

FIG. 3 illustrates a method for manufacturing a GaN based power converter. The method includes the following steps:

S302, defining a first core region and a second core region in a printed circuit board (PCB) ;

S304, constructing a planar transformer in the PCB;

S306, forming a pair of first and second openings through the first and second core regions of the PCB respectively;

S308, assembling a U-shaped magnetic core, which has a pair of first and second core projections, to the PCB, and passing the first and second core projections through the first and second openings respectively;

S310, forming an input port having a low-potential terminal and a high-potential terminal on the PCB;

S312, forming an output port having a low-potential terminal and a high-potential terminal on the PCB;

S314, assembling a primary switch to the PCB, electrically coupling a first conduction terminal of the primary switch to a first terminal of the primary coil winding and electrically coupling a second conduction terminal of the primary switch to the low-potential terminal of the input port;

S316, assembling a synchronous rectifier to the PCB, electrically coupling a first conduction terminal of the synchronous rectifier to a first terminal of the secondary coil winding and electrically coupling a second conduction terminal of the synchronous rectifier to a high-potential terminal of the output port.

Referring to FIG. 4, the constructing the planar transformer in the PCB includes:

S3041: forming a first primary coil winding and a second primary coil windings on a primary coil layer of the PCB, configuring the first primary coil winding to surround the first core region, configuring the second primary coil winding to surround the second core region, and electrically connecting the first primary coil winding and the second primary coil winding in series with each other;

S3042: forming a first secondary coil winding and a second secondary coil windings on a secondary coil layer of the PCB, configuring the first secondary coil winding to surround the first core region, configuring the second secondary coil winding to surround the second core region, and electrically connecting the first secondary coil winding and the second secondary coil winding in parallel to each other;

S3043: forming an auxiliary coil winding on an auxiliary coil layer of the PCB which is deposited between the primary coil layer and secondary coil layer of the PCB; and configuring the auxiliary coil winding to surround one of the first and second core regions;

S3044: forming a first shield coil winding and a second shield coil winding on the auxiliary coil layer of the PCB; configuring the first shield coil winding to surround the first core region; and configuring the second shield coil winding to surround the second core region;

S3045: forming a third shield coil winding and a fourth shield coil winding on a shielding coil layer of the PCB; configuring the third shield coil winding to surround the first core region; and configuring the fourth shield coil winding to surround the second core region;

Based on the above method, the transformer PCB is reduced from six layers to four layers PCB, which effectively reduces the cost of the transformer and by electrically connecting the first secondary coil winding and the second secondary coil winding in parallel, the effective value of the current flowing through the first secondary coil winding and the second secondary coil winding is reduced to half, eventually reduces the copper loss of the transformer to half. In addition, the four layers of transformer PCB is sufficient to solve the EMI in the power converter.

The embodiments were chosen and described in order to best explain the principles of the invention and its practical application, thereby enabling others skilled in the art to understand the invention for various embodiments and with various modifications that are suited to the particular use contemplated. While the methods disclosed herein have been described with reference to particular operations performed in a particular order, it will be understood that these operations may be combined, sub-divided, or re-ordered to form an equivalent method without departing from the teachings of the present disclosure. Accordingly, unless specifically indicated herein, the order and grouping of the operations are not limitations. While the apparatuses disclosed herein have been described with reference to particular structures, shapes, materials, composition of matter and relationships…etc., these descriptions and illustrations are not limiting. Modifications may be made to adapt a particular situation to the objective, spirit and scope of the present disclosure. All such modifications are intended to be within the scope of the claims appended hereto.

Claims

A power converter comprising:

an input port having a low-potential terminal and a high-potential terminal;

an output port having a low-potential terminal and a high-potential terminal;

a planar transformer including a U-shaped magnetic core, a first primary coil winding, a second primary coil winding electrically connected in series with the first primary coil winding, a first secondary coil winding, and a second secondary coil winding electrically connected in parallel to the first secondary coil winding;

a primary switch having a first conduction terminal electrically coupled to the second primary coil winding and a second conduction terminal electrically coupled to the low-potential terminal of the input port.

a synchronous rectifier having a first conduction terminal electrically coupled to the first secondary coil windings and a second conduction terminal electrically coupled to a high-potential terminal of the output port.

wherein the U-shaped magnetic core includes a first core projection and a second core projection;

the first and second primary coil windings are configured to surround the first and second core projections respectively; and

the first and second secondary coil windings are configured to surround the first and second core projections respectively.
The power converter according to claim 1, further comprising a four-layered print circuit board (PCB) ; and wherein:

the first and second primary coil windings are formed on a primary coil layer of the PCB; and

the first and second secondary coil windings are formed on a secondary coil layer of the PCB.
The power converter according to claim 2, wherein the transformer further includes an auxiliary coil winding formed on an auxiliary coil layer of the PCB which is deposited between the primary coil layer and secondary coil layer of the PCB.
The power converter according to claim 3, wherein the auxiliary coil winding is configured to surround one of the first and second core projections.
The power converter according to any one of claims 2 to 4, wherein the transformer further includes:

a first shield coil winding being formed on the auxiliary coil layer of the PCB and configured to surround the first core projection; and

a second shield coil winding being formed on the auxiliary coil layer of the PCB and configured to surround the second core projection.
The power converter according to claim 5, wherein the auxiliary coil winding is surrounded by one of the first and second shield coil windings.
The power converter according to claim 5, wherein the auxiliary coil winding is configured to surround one of the first and second shield coil windings.
The power converter according to any one of claims 2 to 7, wherein the transformer further includes:

a third shield coil winding being formed on a shielding coil layer of the PCB and configured to surround the first core projection; and

a fourth shield coil winding being formed on the shielding coil layer of the PCB and configured to surround the second core projection.
The power converter according to claim 8, wherein the shielding coil layer of the PCB is adjacent to the primary coil layer of the PCB.
The power converter according to claim 8, wherein the shielding coil layer of the PCB is adjacent to the secondary coil layer of the PCB.
The power converter according to any one of claims 2 to 10, further comprising an input coupling capacitor coupled to the input port.
The power converter according to any one of claims 2 to 11, further comprising an output coupling capacitor coupled to the output port.
The power converter according to any one of claims 2 to 12, further comprising:

a first diode having an anode electrically coupled to a first terminal of the auxiliary coil winding; and

a first auxiliary coupling capacitor having a first end electrically coupled to a cathode of the first diode and a second end electrically coupled to a second terminal of the auxiliary coil winding.
The power converter according to any one of claims 1 to 13, wherein the first primary coil winding and the second primary coil winding are respectively wounded on a first primary magnetic column and a second primary magnetic column.
The power converter according to claim 14, wherein number of turns of the first primary coil winding is equal to number of turns of the second primary coil winding.
The power converter according to any one of claims 1 to 13, wherein the first secondary coil winding and the second secondary coil winding are respectively wounded on a first secondary magnetic column and a second secondary magnetic column.
The power converter according to claim 16, wherein number of turns of the first secondary coil winding is equal to number of turns of the second secondary coil winding.
The power converter according to claim 1, wherein an effective value of current flowing through the first secondary coil winding and the second secondary coil winding is reduced to half by electrically connecting the first secondary coil winding and the second secondary coil winding in parallel.
A method for manufacturing a GaN-based power converter, the method comprising:

defining a first core region and a second core region in a printed circuit board (PCB) ;

constructing a planar transformer in the PCB by:

forming a first primary coil winding and a second primary coil windings on a primary coil layer of the PCB, configuring the first primary coil winding to surround the first core region, configuring the second primary coil winding to surround the second core region, and electrically connecting the first primary coil winding and the second primary coil winding in series with each other;

forming a first secondary coil winding and a second secondary coil windings on a secondary coil layer of the PCB, configuring the first secondary coil winding to surround the first core region, configuring the second secondary coil winding to surround the second core region, and electrically connecting the first secondary coil winding and the second secondary coil winding in parallel to each other;

forming a pair of first and second openings through the first and second core regions of the PCB respectively;

assembling a U-shaped magnetic core, which has a pair of first and second core projections, to the PCB, and passing the first and second core projections through the first and second openings respectively;

forming an input port having a low-potential terminal and a high-potential terminal on the PCB;

forming an output port having a low-potential terminal and a high-potential terminal on the PCB;

assembling a primary switch to the PCB, electrically coupling a first conduction terminal of the primary switch to a first terminal of the primary coil winding and electrically coupling a second conduction terminal of the primary switch to the low-potential terminal of the input port;

assembling a synchronous rectifier to the PCB, electrically coupling a first conduction terminal of the synchronous rectifier to a first terminal of the secondary coil winding and electrically coupling a second conduction terminal of the synchronous rectifier to a high-potential terminal of the output port.
The method according to claim 19, wherein construction of the planar transformer further comprises:

forming an auxiliary coil winding on an auxiliary coil layer of the PCB which is deposited between the primary coil layer and secondary coil layer of the PCB; and

configuring the auxiliary coil winding to surround one of the first and second core regions.
The method according to claims 19 or 20, wherein construction of the planar transformer further comprises:

forming a first shield coil winding and a second shield coil winding on the auxiliary coil layer of the PCB;

configuring the first shield coil winding to surround the first core region; and

configuring the second shield coil winding to surround the second core region.
The method according to any one of claims 19 to 21, wherein forming the planar transformer further comprises:

forming a third shield coil winding and a fourth shield coil winding on a shielding coil layer of the PCB;

configuring the third shield coil winding to surround the first core region; and

configuring the fourth shield coil winding to surround the second core region.
The method according to any one of claims 19 to 22, further comprising coupling an input coupling capacitor to the input port.
The method according to any one of claims 19 to 23, further comprising coupling an output coupling capacitor to the output port.
The method according to any one of claims 19 to 24, further comprising:

coupling an anode of a first diode to a first terminal of the auxiliary winding; and

coupling a first end of a first auxiliary coupling capacitor to a cathode of the first diode and coupling a second end of the first auxiliary coupling capacitor to a second terminal of the auxiliary winding.