CN114710058B - Resonant inductor and transformer magnetic core integration method suitable for bidirectional resonant converter - Google Patents

Abstract

The invention provides a resonant inductor and transformer magnetic core integration method suitable for a bidirectional resonant converter and a winding scheme of a low-interlayer capacitance winding based on the magnetic core. Completely separating the resonant inductance of the bidirectional resonant converter from the transformer; the four magnetic columns at the outer side are used as resonant inductance magnetic columns, and the four magnetic columns at the middle are used as eight magnetic columns of the transformer magnetic columns to form an integrated structure; reversely winding windings of adjacent magnetic columns to offset magnetic fluxes of the side columns; the resonance inductance value and the excitation inductance value of the transformer are flexibly adjusted by adjusting the air gap; two magnetic columns of the four magnetic columns of the transformer wind primary side windings, and two magnetic columns wind secondary side windings, so that the interlayer capacitance of the primary side and the secondary side of the transformer is greatly reduced. The invention reduces the number, volume, weight and loss of magnetic pieces in the bidirectional resonant converter; the integrated magnetic core can realize various winding schemes, has extremely high universality, can reduce isolation capacitance of the transformer and reduces common mode interference.

Description

Resonant inductor and transformer core integration method for bidirectional resonant converter

Technical Field

The present invention belongs to the field of power electronics technology and electrical engineering technology, and relates to a method for integrating an inductor and a transformer core capable of reducing interlayer capacitance, and in particular to a resonant inductor and transformer integrated core structure suitable for a bidirectional resonant converter.

Background Art

Bidirectional resonant converters are the core devices for implementing energy management systems such as batteries and supercapacitors, and are widely used in aerospace, electric vehicles, and new energy power generation. Since the primary and secondary sides of the bidirectional resonant converter are each equipped with a resonant cavity, and there are a large number of power magnetic components such as high-frequency inductors and transformers in the circuit, the volume and loss of magnetic components become the key factors limiting the performance optimization of bidirectional resonant converters. Magnetic integration technology allows multiple magnetic components to be integrated into one magnetic core, thereby reducing the number of magnetic components and reducing the volume and weight of the converter. Moreover, through reasonable design, the AC flux of the magnetic components can be reduced or eliminated, thereby improving the efficiency and power density of the converter.

In the literature, the commonly used method for the integrated design of the resonant inductor and transformer core of the bidirectional resonant converter is to use the leakage inductance of the transformer to realize the function of the resonant inductor, and to control the leakage inductance of the transformer through relatively complex and tedious mathematical calculations. It is even necessary to use low-permeability materials as magnetic shunts to form additional magnetic circuits to increase the leakage inductance of the transformer. These methods make the transformer structure very complicated, and the core loss of low-permeability materials is very high, which reduces the efficiency of the transformer. In addition, in these methods, the primary and secondary windings of the transformer are wound on the same magnetic column, which makes the interlayer capacitance large and easily generates common-mode interference.

Summary of the invention

To solve the above problems, the present invention provides a method for integrating a resonant inductor and a transformer core suitable for a bidirectional resonant converter, which eliminates the side columns of the magnetic components, reduces the number, volume, weight and loss of magnetic components in the bidirectional resonant converter, and optimizes the efficiency and power density of the converter. It has extremely high flexibility, and a variety of winding schemes can be realized on the integrated magnetic core, which has extremely high versatility. The winding scheme with low primary and secondary interlayer capacitance can achieve the purpose of reducing the EMI problem of the converter.

The present invention adopts the following technical solutions to achieve the above-mentioned purpose:

The present invention proposes a method for integrating a resonant inductor and a transformer core suitable for a bidirectional resonant converter, including a bidirectional resonant converter, the converter including an inverter, a rectifier circuit, a resonant circuit and a transformer, wherein the resonant circuit is coupled between the inverter and the rectifier circuit, and includes a resonant capacitor, a resonant inductor and a transformer; the resonant inductor and the transformer are integrated into an integrated magnetic component, specifically, the integrated magnetic component includes eight magnetic columns, the resonant inductor and the transformer are wound on the magnetic columns, so that the discrete resonant inductor is integrated into a dual-magnetic column inductor, and a transformer is split into four series transformers, and the side columns are eliminated by opposite winding methods; two magnetic columns in the four-magnetic column transformer are wound on the primary side, and two magnetic columns are wound on the secondary side, so as to realize a winding scheme in which the primary and secondary windings do not contact each other, so that the transformer has extremely low interlayer capacitance.

The resonant inductor and transformer in the traditional bidirectional resonant converter are integrated into one magnetic core. Using magnetic integration technology, two traditional discrete ER-type magnetic core inductors are integrated into a dual-column inductor. A transformer is split into four series transformers, and the eight side columns of the transformer are eliminated through magnetic integration technology, leaving only four magnetic columns. The four-column transformer can realize a variety of winding schemes and is more flexible than the original single transformer.

Furthermore, the integrated magnetic component has a three-layer structure, including an upper magnetic core cover, a middle layer of inductance and transformer windings, and a bottom magnetic core base, wherein the magnetic core base includes a magnetic plate and eight magnetic columns integrated on the magnetic plate; wherein four magnetic columns form a row, and the eight magnetic columns are evenly and evenly spaced into 2 rows and 4 columns.

Furthermore, the resonant inductor and transformer in the traditional bidirectional resonant converter are integrated into a magnetic core, which has eight magnetic columns, of which the two columns on both sides are primary resonant inductor magnetic columns and secondary resonant inductor magnetic columns, respectively, and the four middle magnetic columns are transformer magnetic columns; the resonant inductor windings are wound on the primary and secondary resonant inductor magnetic columns, respectively, and the transformer windings are wound on the transformer magnetic columns, wherein the resonant inductor windings are wound on the two magnetic columns of the primary and secondary resonant inductor magnetic columns in opposite directions, and the transformer windings are wound clockwise on the four magnetic columns of the transformer magnetic columns.

Furthermore, the resonant circuit includes a first resonant capacitor C _r1 , a second resonant capacitor C _r2 , a first resonant inductor L _r1 , a second resonant inductor L _r2 and an excitation inductor L _m of a transformer; wherein the first resonant capacitor C _r1 , the first resonant inductor L _r1 and the excitation inductor L _m of the transformer are connected in series in sequence to form a first resonant series circuit, and both ends of the first resonant series circuit are connected to the midpoints of the two bridge arms of the inverter circuit; the second resonant capacitor C _r2 , the second resonant inductor L _r2 and the excitation inductor L _m of the transformer are connected in series in sequence to form a second resonant series circuit, and both ends of the second resonant series circuit are connected to the midpoints of the two bridge arms of the rectifier circuit.

Furthermore, two traditional discrete ER-type magnetic core inductors are integrated into a dual-column inductor using magnetic integration technology. Two identical first resonant inductor L _r1 windings are wound in opposite directions on the primary resonant inductor magnetic column, and two identical second resonant inductor L _r2 windings are wound in opposite directions on the secondary resonant inductor magnetic column, so that the magnetic flux generated by the windings in adjacent magnetic columns is equal in magnitude and opposite in direction, and the combined magnetic flux cancels out, so the four side columns can be removed and the inductor is integrated into a dual-column inductor.

Furthermore, in order to reduce the loss caused by the secondary current stress and high-frequency winding eddy current effect of the bidirectional resonant converter, the transformer in the bidirectional resonant converter is split into four series transformers; then, the eight side columns of the series transformer are eliminated through magnetic integration technology, and only four magnetic columns are retained. The four-magnetic column transformer can realize a variety of winding schemes, which is more flexible than the original single transformer; then, the original and secondary sides are separately wound on the four-magnetic column transformer to achieve the effect of reducing the interlayer capacitance.

Furthermore, the two diagonal magnetic columns in the four-column transformer are grouped together, one group is used to wind the primary winding of the transformer, and the other group is used to wind the secondary winding of the transformer. At the same time, the winding directions of the transformer windings on the two adjacent magnetic columns are ensured to be opposite, thereby realizing a winding scheme in which the primary and secondary windings do not contact each other, so that the transformer has extremely low interlayer capacitance and can be used in situations with high EMI requirements.

Compared with the prior art, the present invention adopts the above technical solution and has the following technical effects:

(1) The use of magnetic integration technology eliminates the side columns of magnetic components, greatly reducing the number, volume, weight and loss of magnetic components, which is conducive to optimizing the efficiency and power density of the converter;

(2) The resonant inductance and transformer excitation inductance can be flexibly adjusted by adjusting the air gap between the windings;

(3) A variety of winding schemes can be realized on the integrated magnetic core, which has extremely high versatility and flexibility;

(4) The use of a winding scheme that can reduce interlayer capacitance can reduce the isolation capacitance of the transformer, effectively suppressing the common-mode interference problem of the converter, and is suitable for occasions with high isolation requirements;

(5) The use of a winding scheme with low primary-secondary interlayer capacitance can achieve the goal of reducing the EMI problem of the converter.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a schematic diagram of a method for integrating a resonant inductor and a transformer core suitable for a bidirectional resonant converter proposed in the present invention;

FIG2 is a schematic diagram of the side-column-free magnetic integration technology of the present invention;

FIG3 is a schematic diagram of four series-connected transformers in the present invention;

FIG4 is an electrical equivalent diagram of a transformer in the present invention;

FIG5 is a schematic diagram of a transformer winding scheme proposed in the present invention that can reduce interlayer capacitance.

DETAILED DESCRIPTION

The technical solution of the present invention is further described below in conjunction with the accompanying drawings and embodiments.

As shown in Figure 1, it is a schematic diagram of a method for integrating a resonant inductor and a transformer core suitable for a bidirectional resonant converter proposed in the present invention, including a bidirectional resonant converter, the converter including an inverter, a rectifier circuit, a resonant circuit and a transformer, wherein the resonant circuit is coupled between the inverter and the rectifier circuit, and includes a resonant capacitor, a resonant inductor and a transformer.

The converter is a full-bridge converter, including switch tubes _S1 , _S2 , _S3 , and _S4 , and the rectifier circuit includes switch tubes _S5 , _S6 , _S7 , and _S8 , wherein the source of _S1 in the full-bridge converter is connected to the drain of _S2 , the source of _S3 is connected to the drain of _S4 , the drain of _S1 is connected to the drain of _S3 , and the source of _S2 is connected to the source of _S4 , respectively forming two bridge arms. In the rectifier circuit, the source of _S5 is connected to the drain of _S6 , the source of _S7 is connected to the drain of _S8 , the drain of _S5 is connected to the drain of _S7 , and the source of _S6 is connected to the source of _S8 , respectively forming two bridge arms.

The resonant circuit includes a first resonant capacitor C _r1 , a second resonant capacitor C _r2 , a first resonant inductor L _r1 , a second resonant inductor L _r2 , and an excitation winding L _m of a transformer. The first resonant capacitor C _r1 , the first resonant inductor L _r1 , and the excitation winding L _m of the transformer are sequentially connected in series to form a first resonant series circuit, and both ends of the first resonant series circuit are connected to the midpoints of the two bridge arms of the inverter circuit; the second resonant capacitor C _r2 , the second resonant inductor L _r2 , and the excitation winding L _m of the transformer are sequentially connected in series to form a second resonant series circuit, and both ends of the second resonant series circuit are connected to the midpoints of the two bridge arms of the rectifier circuit.

The resonant inductor and transformer in the traditional bidirectional resonant converter are integrated into an integrated magnetic component. Specifically, the resonant inductor and transformer are respectively integrated into the magnetic core, and the two traditional discrete ER-type magnetic core inductors are integrated into a dual-column inductor using magnetic integration technology. A transformer is split into four series transformers, and the eight side columns of the transformer are eliminated through magnetic integration technology, leaving only four magnetic columns. The four-column transformer can realize a variety of winding schemes, which is more flexible than the original single transformer.

The integrated magnetic component includes three parts: a magnetic core cover, an inductor and transformer winding, and a magnetic core base. The magnetic core base includes a magnetic plate and eight magnetic columns integrated on the magnetic plate. The inductor and transformer winding can be a planar PCB winding or a winding. The magnetic core base includes a magnetic plate and eight magnetic columns integrated on the magnetic plate; wherein four magnetic columns are in a row, and eight magnetic columns are evenly spaced in 2 rows and 4 columns. The two columns of magnetic columns on both sides of the eight magnetic columns are the primary resonant inductor magnetic columns and the secondary resonant inductor magnetic columns, respectively, and the four magnetic columns in the middle are transformer magnetic columns; the resonant inductor windings are wound on the primary and secondary resonant inductor magnetic columns, respectively, and the transformer windings are wound on the transformer magnetic columns, wherein the resonant inductor windings are wound on the two magnetic columns of the primary and secondary resonant inductor magnetic columns in opposite directions, and the transformer windings are wound clockwise on the four magnetic columns of the transformer magnetic columns.

As shown in FIG2 , it is a schematic diagram of the side-column-free magnetic integration technology described in the present invention. Two identical first resonant inductor L _r1 windings are wound in opposite directions on the primary resonant inductor magnetic column, and two identical second resonant inductor L _r2 windings are wound in opposite directions on the secondary resonant inductor magnetic column, and the direction of the magnetic flux is changed so that the magnetic flux generated by the windings in adjacent magnetic columns is equal in magnitude and opposite in direction, and the combined magnetic flux cancels out, then the two adjacent side columns can be removed. Similarly, the outer side columns can be removed according to the combined magnetic flux cancellation, and finally the side-column-free magnetic integration design is realized.

In the figure, the circle represents the ER core column, the two sides of the column are the core side columns, and the dotted line represents the winding direction of the winding.

As shown in Fig. 3, it is a schematic diagram of four series transformers in the present invention, where a large transformer T is split into four small transformers T ₁ , T ₂ , T ₃ , and T ₄ . The transformer windings are wound on four magnetic poles in clockwise/counterclockwise directions.

In the figure, the circle represents the transformer core magnetic column, the two sides of the magnetic column are the core side columns, the dotted line represents the winding direction of the winding, and the four small transformers are connected in series through the winding.

As shown in FIG. 4 , it is the electrical equivalent diagram of the transformer described in the present invention. After the large transformer is equivalently split into four small transformers, the loss caused by the secondary current stress of the bidirectional resonant converter and the high-frequency winding eddy current effect can be reduced.

Based on the four small transformers after splitting, the eight side columns of the series transformer are eliminated through magnetic integration technology, leaving only four magnetic columns to form a four-column transformer. The four-column transformer can realize a variety of winding schemes, which is more flexible than the original single transformer. The primary and secondary sides are wound separately on the four-column transformer to achieve the effect of reducing the interlayer capacitance.

As shown in FIG5 , it is a schematic diagram of a transformer winding scheme proposed in the present invention that can reduce interlayer capacitance. Based on the above-mentioned integrated magnetic component, the two diagonal magnetic columns in the four-column transformer are grouped together, one group of magnetic columns is wound around the primary side, and one group of magnetic columns is wound around the secondary side, and the winding directions of the windings on adjacent magnetic columns are opposite. This winding method can prevent the primary and secondary windings from contacting each other, so that the transformer has extremely low interlayer capacitance and can be used in situations with high EMI requirements. At the same time, under this winding scheme, the magnetic flux in each magnetic column can have two flow directions, and the magnetic flux area is increased under the same magnetic plate thickness, so the thickness of the core cover can be reduced.

Among them, the circle represents the transformer magnetic column, the dotted line represents the winding direction of the winding, the arrow represents the magnetic flux flow direction of each magnetic column, P represents the magnetic core where the primary winding of the transformer is located, S represents the magnetic core where the secondary winding of the transformer is located, the two primary side windings are connected, and the secondary side windings are not connected.

The above embodiments are only for illustrating the technical idea of the present invention, and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the present invention.

Claims (5)

1. A method for integrating a resonant inductor and a transformer core for a bidirectional resonant converter, wherein the bidirectional resonant converter comprises an inverter, a rectifier circuit, a resonant circuit and a transformer, wherein the resonant circuit is coupled between the inverter and the rectifier circuit and comprises a resonant capacitor, a resonant inductor and a transformer; the resonant inductor and the transformer are integrated into an integrated magnetic component, specifically, The resonant circuit comprises a first resonant capacitor C _r1 , a second resonant capacitor C _r2 , a first resonant inductor L _r1 , a second resonant inductor L _r2 and a transformer excitation inductor L _m ; wherein the first resonant capacitor C _r1 , the first resonant inductor L _r1 and the transformer excitation inductor L _m are sequentially connected in series to form a first resonant series circuit, and both ends of the first resonant series circuit are connected to the midpoints of the two bridge arms of the inverter circuit; the second resonant capacitor C _r2 , the second resonant inductor L _r2 and the transformer excitation inductor L _m are sequentially connected in series to form a second resonant series circuit, and both ends of the second resonant series circuit are connected to the midpoints of the two bridge arms of the rectifier circuit; The integrated magnetic component is a three-layer structure, including an upper magnetic core cover, an intermediate inductor and transformer winding, and a bottom magnetic core base, wherein the magnetic core base includes a magnetic plate and eight magnetic columns integrated on the magnetic plate; wherein four magnetic columns form a row, and the eight magnetic columns are evenly spaced and arranged in two rows and four columns; Wind the resonant inductor and transformer on the magnetic poles. Specifically, the two columns of magnetic poles on both sides of the eight magnetic poles are the primary resonant inductor magnetic poles and the secondary resonant inductor magnetic poles, and the four magnetic poles in the middle are the transformer magnetic poles. Wind the resonant inductor windings on the primary and secondary resonant inductor magnetic poles, and wind the transformer windings on the transformer magnetic poles. The resonant inductor windings are wound on the two magnetic poles of the primary and secondary resonant inductor magnetic poles in opposite directions, and the transformer windings are wound on the four magnetic poles of the transformer magnetic poles in a clockwise direction. Magnetic integration technology is used to integrate discrete resonant inductors into dual-column inductors; one transformer is split into four transformers, and the four transformers are integrated into a four-column transformer using magnetic integration technology; two of the four-column transformers are wound on the primary side, and two are wound on the secondary side, to achieve a non-contact winding scheme for the primary and secondary windings, thereby reducing the interlayer capacitance of the transformer. 2. The method for integrating a resonant inductor and a transformer core suitable for a bidirectional resonant converter according to claim 1 is characterized in that two identical first resonant inductor L _r1 windings are wound on the primary resonant inductor magnetic column in opposite directions, and two identical second resonant inductor L _r2 windings are wound on the secondary resonant inductor magnetic column in opposite directions to eliminate side columns in the magnetic field. 3. The method for integrating a resonant inductor and a transformer core suitable for a bidirectional resonant converter according to claim 1 or 2 is characterized in that the four transformers are integrated into a four-column transformer using magnetic integration technology, specifically: the adjacent core windings in the four cores of the four transformers are reversely wound on the magnetic columns to eliminate the side columns to form a four-column transformer. 4. The method for integrating a resonant inductor and a transformer core suitable for a bidirectional resonant converter according to any one of claim 3, characterized in that two diagonal magnetic columns in a four-column transformer are grouped together, one group is wound around the primary winding of the transformer, and the other group is wound around the secondary winding of the transformer. 5. The method for integrating a resonant inductor and a transformer core suitable for a bidirectional resonant converter according to claim 4, wherein the inductor and the transformer winding are planar PCB windings or windings.