CN108492958B - A series multi-phase interleaved coupled inductor structure and its control method - Google Patents

Abstract

The invention discloses a series multi-phase interleaved coupled inductance structure and a control method thereof, which is composed of several series-connected multi-phase coupled inductance units, each multi-phase coupled inductance unit uses a single magnetic core to wind N winding coils, N The winding coils are positively and negatively coupled in turn, and N is the phase number of the coupled inductance; the magnetic core of each multi-phase coupled inductance unit adopts a ring magnetic ring structure; the odd-numbered phase windings on each magnetic core have the same winding direction, and the even-numbered The winding directions of the phase windings are the same, and the winding directions of the odd-numbered and even-numbered phases are opposite, so that each winding on each magnetic core is sequentially coupled positively and negatively. The series multi-phase interleaved coupling inductor proposed by the present invention can simultaneously improve the dynamic performance and steady-state performance of the coupled inductor and reduce the volume of the coupled inductor, has a larger equivalent steady-state inductance optimization range than the full negative coupling method, and can realize The full range of coupling coefficient design values.

Description

A series multi-phase interleaved coupled inductor structure and its control method

technical field

The invention relates to the technical field of coupled inductors used in multi-phase interleaved converters, in particular to a series multi-phase interleaved coupled inductor structure and a control method thereof.

Background technique

With the rapid development of new energy power generation, electric vehicles, energy storage systems and other fields, non-isolated DC-DC converters have received extensive attention. In many occasions, such as fuel cells, aviation power supplies, communication power supplies, radar transmitters, electroplating power supplies, server power supplies, etc., there are high requirements for the power level, current ripple, and converter size of DC power supplies. Therefore, High-performance non-isolated multi-phase interleaved parallel DC-DC converters have a huge market demand.

In the prior art, traditional multi-phase interleaved parallel DC-DC converters use independent inductors. This solution makes the converter in the phase current ripple of the inductor (ie steady-state performance), the dynamic performance of the converter and the size of the converter. Three aspects are difficult to further improve. In the occasions where the dynamic performance, steady-state performance and size of the converter are high, the traditional solution using independent inductors may not meet the design requirements.

At present, there are some magnetic integration technologies that use multi-phase negative coupling and traditional interleaved control methods to improve the dynamic and steady-state performance of the converter. However, the range of the coupling coefficient of the converter used in this solution is limited, and the maximum coupling coefficient of the coupled inductor is inversely proportional to the number of coupled phases, that is, as the number of coupled phases increases, the maximum coupling coefficient of the coupled inductor decreases rapidly, which gives the coupling The design and manufacture of inductors brings difficulties. At the same time, the full negative coupling method does not make the equivalent steady-state inductance of the coupled inductor increase significantly. It can be seen from the equivalent steady-state inductance surface diagram of the coupled inductor under different duty cycles and different coupling coefficients that this A full negative coupling method, under a wide range of duty cycle and coupling coefficient, the equivalent steady-state inductance value is significantly smaller than the separation inductance value without coupling, that is, if the converter simultaneously obtains higher transient performance and Steady-state performance requires sacrificing the size of the coupled inductor and greatly increasing the self-inductance of each phase of the coupled inductor.

In summary, the dynamic performance, steady-state performance and volume of coupled inductors restrict each other, and the existing full negative coupling magnetic integration technology and control method can only better improve the dynamic performance and stable performance of coupled inductors. state performance, but the size of the coupled inductor cannot be reduced at the same time, and this method has a limited ability to improve the steady-state performance, and there is a limit on the maximum coupling coefficient, it is difficult to expand to multi-phase and there are difficulties in manufacturing when used in multi-phase converters .

At present, there is still no effective solution to simultaneously improve the dynamic performance and steady-state performance of the coupled inductor and reduce the volume of the coupled inductor.

Contents of the invention

In order to solve the deficiencies of the prior art, one of the objectives of the present invention is to provide a series multi-phase interleaved coupled inductor structure, which is used to improve the dynamic performance and steady-state performance of the coupled inductor while reducing the volume of the coupled inductor, which has a larger Equivalent steady-state inductance optimization range, and can achieve a full range of coupling coefficient design values.

A series multi-phase interleaved coupled inductor structure, comprising:

A number of multi-phase coupled inductance units in series, each multi-phase coupled inductance unit adopts N winding coils wound on a single magnetic core, and the N winding coils are positively and negatively coupled in turn, N is the phase number of the coupled inductance; each of the The magnetic core of the multi-phase coupled inductance unit adopts a ring magnetic ring structure;

The odd phase windings on each magnetic core have the same winding direction, the even phase windings have the same winding direction, and the odd phase and even phase windings have opposite winding directions, so as to realize positive and negative coupling of each winding on each magnetic core.

In a further technical solution, the series connection mode of the multi-phase coupled inductance unit is that the input end of each phase winding on each multi-phase coupled inductance unit is connected with the output end of the corresponding winding on the previous multi-phase coupled inductance unit, and each The output end of each phase winding on the first polyphase coupled inductance unit is connected to the input end of the corresponding winding on the next multiphase coupled inductance unit, and the input end of each phase winding of the first multiphase coupled inductance unit is the total coupled inductance The input end of each phase winding and the output end of each phase winding of the last multi-phase coupled inductance unit are the output ends of each phase winding of the total coupled inductance.

The total volume of the coupled inductor is determined by the number of series of coupled inductors connected in series, and the more series connected, the smaller the total volume of the coupled inductor.

As the number of stages is more, under the condition of the same total self-inductance, the number of turns required for each stage of winding is smaller, and the circumference required for the corresponding magnetic rings of each level is smaller, and the volume of the magnetic ring is proportional to the square of the circumference. , the volume decreases at a quadratic rate, so the more series series, the smaller the total volume of coupled inductors.

The manufacturing steps of each multi-phase coupled inductance unit of a series multi-phase interleaved coupled inductance structure are as follows:

(1) Draw the three-dimensional surface diagram of the equivalent steady-state inductance of the coupled inductance unit when using different coupling coefficients and different duty cycle controls under different phase numbers;

(2) Determine the optimal coupling coefficient corresponding to the maximum equivalent steady-state inductance of the coupled inductor when the converter works at the rated duty cycle;

(3) Calculate the current flowing through the inductance of each phase according to the design power of the converter, and determine the winding wire diameter;

(4) According to the size of the coupled inductance to be achieved, determine the number of series required for the coupled inductance;

(5) According to the coupling coefficient relationship of the toroidal core under different reluctance and different turns of the winding, determine the size of the toroidal core and the number of turns of the winding for each toroidal coupling inductor.

In the described step (1), according to the steady-state operation of the circuit, the inductance has the characteristics of volt-second balance in a switching cycle, and the steady-state relational expression is written to the multi-phase coupled inductance matrix column accordingly, and the steady-state relational expression is changed by mathematical transformation The coupling inductance part in is decoupled, and the equivalent decoupling steady-state inductance of the multi-phase coupled inductance can be obtained; with the coupling coefficient and duty cycle as the independent variables, and the equivalent decoupling steady-state inductance as the dependent variable, it can be drawn Three-dimensional surface diagram of the equivalent steady-state inductance of the coupled inductor unit under different coupling coefficients and different duty cycle control.

The equivalent decoupling inductance has different values under different duty cycles and different coupling coefficients. The larger the equivalent steady-state inductance, it means that after coupling the independent inductance, the larger the equivalent steady-state inductance is, which can be more It is good to reduce the inductor ripple and improve the steady-state performance of the converter. The three-dimensional surface diagram of the equivalent steady-state inductance described in the article describes the change of the equivalent steady-state inductance under different duty ratios and coupling coefficients under the same winding conditions. Through the selection of duty ratios and coupling coefficients, the equivalent The duty cycle and coupling coefficient when the coupled inductance is maximum, so that the performance of the coupled inductance can be optimized.

In the step (2), in actual converter design, the duty cycle and coupling coefficient are affected by many factors. The selection of duty cycle and coupling coefficient is also based on the consideration of various factors according to the design of different converters. Combined with the actual solution to determine the duty cycle and coupling coefficient, the three-dimensional surface diagram in this paper only shows the consideration from the perspective of coupling inductance. However, in the actual converter design, it is generally necessary to calculate the rated duty cycle according to the function of the converter, and then select the coupling coefficient on this basis, and finally complete the design of the coupled inductor.

The main innovation of the present invention lies in the coupling mode and control mode of the coupled inductor, and the performance of the coupled inductor is improved by combining the two. The specific design of current and wire diameter can refer to the general design method, for example, you can refer to the design method of "Theory and Design of Magnetic Components of Switching Power Supply".

For the specific coupling coefficient relationship of the present invention, reference can be made to the specific manufacturing process of coupled inductors.

Only consider the main factors affecting the volume of the coupled inductor. When the number of series increases, the circumference required for each phase magnetic ring becomes smaller, and the volume of each phase magnetic ring is approximately proportional to the square of the circumference. It can be seen that the increase of the series can be The total volume of the coupled inductor is reduced. Since there are too many factors affecting the size of the inductor, and it involves the production level of the inductor, only a general conclusion is given here, that is, increasing the number of coupled inductors can reduce the total volume of the coupled inductor. The invention mainly relates to the optimization of the inductive coupling mode and the control mode.

Further, the series-type multi-phase coupled inductor unit can be used in a circuit of a converter requiring multi-phase interleaved control, such as a traditional multi-phase interleaved DC-DC converter.

The control method of the series multiphase interleaved coupled inductor structure, the control method of the series multiphase coupled inductor unit is a 180° interleaved control method, that is, the charging and discharging states of adjacent windings lag behind the phase angle of 180° in turn.

Further, the equivalent steady-state inductance value (expressed in per unit value) of the series multi-phase coupled inductance unit is:

Among them, L _eq is the equivalent steady-state inductance value of the series multi-phase coupled inductor unit, L is the independent inductance value which is the same as the self-inductance of each phase of the series multi-phase coupled inductor unit, D is the duty cycle, and k is the coupling coefficient .

The equivalent steady-state inductance value described in the present invention can explain the change of the equivalent steady-state inductance value after multi-phase independent inductive coupling. Specifically, after independent inductive coupling, the equivalent steady-state inductance value is at a certain The duty cycle and coupling range will become larger, that is, after independent inductive coupling, it is equivalent to using a larger independent inductance, so independent inductive coupling will improve the steady-state characteristics of the converter. The expression in this article is the basis of the three-dimensional surface diagram of the equivalent steady-state inductance above. Through this expression, the three-dimensional surface diagram can be drawn, and then through the surface diagram, according to the specific converter design requirements, comprehensively consider the design requirements of various aspects, and choose the best duty cycle and coupling coefficient.

Further, the equivalent transient inductance value (expressed in per unit value) of the series multi-phase coupled inductance unit is:

Among them, L _tr is the equivalent transient inductance value of the series multiphase coupled inductor unit, L is the independent inductance value which is the same as the self-inductance of each phase of the series multiphase coupled inductor unit, and k is the coupling coefficient.

It can be seen from the equivalent transient inductance expression of the series multi-phase coupled inductance unit that its equivalent transient inductance value becomes smaller compared with the independent inductance, and the dynamic response of the converter becomes faster, so the converter can be improved. transient performance.

Further, the positive and negative coupling of each phase winding in turn, when the windings are positively coupled, the range of the coupling coefficient k is 0<k<1, and when the windings are negatively coupled, the range of the coupling coefficient k is -1<k<0.

Further, the 180° interleaving control method, taking the traditional multi-phase DC-DC converter as an example, is that the conduction state of each corresponding switch tube is sequentially delayed by 180° phase angle.

Compared with prior art, the beneficial effect of the present invention is:

The solution of series multi-phase interleaved coupling inductors proposed by the present invention has a wider range of coupling coefficients and is easy to design. And in a very large range of duty cycle and coupling coefficient, the equivalent steady-state inductance can be increased after inductive coupling, and the increase factor is significantly greater than the solution of full negative coupling, so the series multi-phase inductance proposed by the present invention Interleaved coupled inductors have better steady-state inductance performance. At the same time, the series multi-phase interleaved coupling inductor proposed by the present invention has smaller equivalent transient inductance, so the series multi-phase interleaved coupled inductor proposed by the present invention has better transient performance.

Description of drawings

The accompanying drawings constituting a part of the present application are used to provide further understanding of the present application, and the schematic embodiments and descriptions of the present application are used to explain the present application, and do not constitute improper limitations to the present application.

Fig. 1 is the coupling inductance structure of described four-phase positive and negative coupling four-stage series connection;

Figure 2 shows the traditional four-phase interleaved parallel DC-DC topology using the proposed novel series multi-phase interleaved coupled inductors;

Figure 3 shows the traditional four-phase interleaved parallel DC-DC topology switch control signal using the proposed new series multi-phase interleaved coupled inductor;

Figure 4 is an independent inductance structure with the same self-inductance value of each phase of the series four-phase coupled inductance unit;

Fig. 5 (a) is the equivalent value corresponding to the equivalent steady-state inductance of the series-type four-phase coupled inductance unit under different duty ratios and different coupling coefficient ranges;

Fig. 5 (b) is the side view of Fig. 5 (a);

Fig. 6(a) is the corresponding equivalent value of the equivalent steady-state inductance of the four-phase coupled inductance unit adopting the full negative coupling mode under different duty ratios and different coupling coefficient ranges;

Fig. 6(b) is a side view of Fig. 6(a).

Detailed ways

It should be pointed out that the following detailed description is exemplary and intended to provide further explanation to the present application. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

It should be noted that the terminology used here is only for describing specific implementations, and is not intended to limit the exemplary implementations according to the present application. As used herein, unless the context clearly dictates otherwise, the singular is intended to include the plural, and it should also be understood that when the terms "comprising" and/or "comprising" are used in this specification, they mean There are features, steps, operations, means, components and/or combinations thereof.

In a typical implementation of the present application, as shown in FIG. 1 , a four-stage series-connected four-phase coupled inductor with positive and negative coupling is provided, and a traditional four-phase DC-DC converter topology is used to verify the performance of the coupled inductor. The coupled inductor structure of the four-stage series-connected four-phase positive and negative coupling is shown in FIG. 1 .

The four-phase positive and negative coupling four-level series coupled inductor includes four series connected four-phase coupled inductor units, and each four-phase coupled inductor unit is made by winding four winding coils on a single magnetic core and sequentially coupled positively and negatively .

The preferred magnetic core structure in this embodiment is an annular magnetic ring structure.

The winding directions of phase 1 and phase 3 on each magnetic core are the same, the winding directions of phase 2 and phase 4 are the same, the winding directions of winding 1 and winding 2 and 4 are opposite, and the winding directions of winding 3 and winding 2 and 4 are opposite, so as to realize the magnetic core The upper windings are positively and negatively coupled sequentially, that is, the mutual inductances M ₁₂ , M ₁₄ , M ₂₃ , and M ₃₄ are negative, and the mutual inductances M ₁₃ , M ₂₄ are positive.

The series connection of four four-phase coupled inductor units is as follows: the input end of each phase winding on each four-phase coupled inductor is connected to the output end of the corresponding winding on the previous multi-phase coupled inductor, each of the four-phase coupled inductors The output end of the phase winding is connected to the input end of the corresponding winding on the next four-phase coupled inductor, the input end of each phase winding of the first four-phase coupled inductor is the input end of each phase winding of the total coupled inductor, and the last four-phase The output end of each phase winding of the coupled inductor is the output end of each phase winding of the total coupled inductor.

Compared with a single four-phase coupled inductor, the four-stage coupled inductor in series has a smaller volume and a larger heat dissipation area.

As a preferred specific implementation case, in order to verify the performance of the proposed new series multi-phase interleaved coupled inductor, the circuit topology adopts the traditional four-phase interleaved parallel DC-DC topology, as shown in Figure 2.

Taking the converter working in the boost mode as an example, the conduction states of the switch tubes S ₁ , S ₃ , S ₅ , and S ₇ lag behind the phase angle by 180° in turn, and the switch tubes S ₂ , S ₄ , S ₆ , and S ₈ adopt synchronous The rectification mode is complementary to the conduction state of S ₁ , S ₃ , S ₅ , and S ₇ (the dead zone is not considered here). The control signal of the switch tube is shown in Figure 3, and its duty cycle range is 0<D<1.

When each winding is wound symmetrically, the four-phase coupled inductance matrix is:

This matrix is intended to represent the characteristics of the positive and negative coupling of coupled inductors. This matrix clearly shows the difference between the present invention and the existing negative coupled inductor technology. In the design of multi-phase converters, this matrix is a basic matrix for converters analysis and calculation.

The equivalent steady-state inductance value (expressed in per unit value) of the series-type four-phase coupled inductance unit is:

Among them, L _eq is the equivalent steady-state inductance value of the series four-phase coupled inductor unit, L is the same independent inductance value as the self-inductance of each phase of the series four-phase coupled inductor unit, and k is the coupling coefficient.

The equivalent transient inductance value (expressed in per unit value) of the series-type four-phase coupled inductance unit is:

Among them, L _tr is the equivalent transient inductance value of the series four-phase coupled inductance unit, L is the independent inductance value which is the same as the self-inductance of each phase of the series four-phase coupled inductance unit, and k is the coupling coefficient.

The independent inductance structure with the same self-inductance value of each phase of the series four-phase coupled inductance unit is shown in Figure 4.

The corresponding equivalent values of the equivalent steady-state inductance of the series-type four-phase coupled inductance unit under different duty ratios and different coupling coefficient ranges are shown in Figure 5(a), and its side view is shown in Figure 5(b).

In the existing full negative coupling magnetic integration technology, the equivalent steady-state inductance of the four-phase coupled inductance unit using the full negative coupling mode corresponds to the equivalent value under different duty ratios and different coupling coefficient ranges as shown in Figure 6 ( a), its side view is shown in Figure 6(b).

It can be seen that the series multi-phase interleaved coupling inductor solution proposed by the present invention has a wider coupling coefficient range and is easy to design. And in a very large range of duty cycle and coupling coefficient, the equivalent steady-state inductance can be increased after inductive coupling, and the increase factor is significantly greater than the solution of full negative coupling, so the series multi-phase inductance proposed by the present invention Interleaved coupled inductors have better steady-state inductance performance. At the same time, the series multi-phase interleaved coupling inductor proposed by the present invention has smaller equivalent transient inductance, so the series multi-phase interleaved coupled inductor proposed by the present invention has better transient performance.

The above descriptions are only preferred embodiments of the present application, and are not intended to limit the present application. For those skilled in the art, various modifications and changes may be made to the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of this application shall be included within the protection scope of this application.

Claims (9)

1. A series multi-phase interleaved coupled inductor structure, characterized in that it comprises: A number of multi-phase coupled inductance units in series, each multi-phase coupled inductance unit adopts N winding coils wound on a single magnetic core, and the N winding coils are positively and negatively coupled in turn, N is the phase number of the coupled inductance; each of the The magnetic core of the multi-phase coupled inductance unit adopts a ring-shaped magnetic ring structure; the odd-numbered phase windings on each magnetic core have the same winding direction, the even-numbered phase windings have the same winding direction, and the odd-numbered and even-numbered phase windings have the opposite winding direction, so that each Each winding on the magnetic core is positively and negatively coupled in turn; The equivalent steady-state inductance value of the series multiphase coupled inductance unit is expressed as per unit value: Among them, L _eq is the equivalent steady-state inductance value of the series multi-phase coupled inductor unit, L is the independent inductance value which is the same as the self-inductance of each phase of the series multi-phase coupled inductor unit, D is the duty cycle, and k is the coupling coefficient . 2. A kind of series multiphase interleaved coupling inductor structure as claimed in claim 1, is characterized in that, the series connection mode of described multiphase coupling inductor unit is: each phase winding input terminal on each multiphase coupled inductor unit It is connected to the output end of the corresponding winding on the last multi-phase coupled inductance unit, and the output end of each phase winding on each multi-phase coupled inductance unit is connected to the input end of the corresponding winding on the next multi-phase coupled inductance unit, The input end of each phase winding of the first multi-phase coupled inductor unit is the input end of each phase winding of the total coupled inductor, and the output end of each phase winding of the last multi-phase coupled inductor unit is the output end of each phase winding of the total coupled inductor end. 3. A kind of series multi-phase interleaved coupling inductor structure as claimed in claim 1, it is characterized in that, the total volume of described coupled inductor is determined by the number of series of coupled inductors, the more series of series, the more coupling inductors The total volume is smaller. 4. A series multi-phase interleaved coupled inductor structure as claimed in claim 1, characterized in that said series multi-phase coupled inductor unit can be used in a circuit of a converter requiring multi-phase interleaved control. 5. A kind of series type multi-phase interleaved coupled inductance structure as claimed in claim 1, is characterized in that, the equivalent transient inductance value of described series type multi-phase coupled inductance unit promptly expresses with per unit value as: Among them, L _tr is the equivalent transient inductance value of the series multiphase coupled inductor unit, L is the independent inductance value which is the same as the self-inductance of each phase of the series multiphase coupled inductor unit, and k is the coupling coefficient. 6. The control method of a kind of series multi-phase interleaved coupling inductor structure as claimed in claim 1, is characterized in that, the control mode of series multi-phase coupled inductor unit is 180 ° interleaving control mode, that is, the charging of adjacent windings The discharge state lags behind 180° phase angle in turn. 7. The control method of a kind of series multi-phase interleaved coupling inductance structure as claimed in claim 6, is characterized in that, each phase winding of described positive and negative coupling in turn, when positive coupling between windings, its coupling coefficient k The range of the coupling coefficient k is 0<k<1, and when the windings are negatively coupled, the range of the coupling coefficient k is -1<k<0. 8. The control method of a kind of series multi-phase interleaved coupling inductor structure as claimed in claim 6, it is characterized in that, described 180 ° interleaved control mode, for every corresponding switching tube conduction state lags behind 180 ° phase angle successively . 9. the manufacture method of each polyphase coupled inductance unit of a kind of serial multiphase interleaved coupled inductance structure as claimed in claim 1, it is characterized in that, the steps are: (1) Draw the three-dimensional surface diagram of the equivalent steady-state inductance of the coupled inductance unit when using different coupling coefficients and different duty cycle controls under different phase numbers; (2) Determine the optimal coupling coefficient corresponding to the maximum equivalent steady-state inductance of the coupled inductor when the converter works at the rated duty cycle; (3) Calculate the current flowing through the inductance of each phase according to the design power of the converter, and determine the winding wire diameter; (4) According to the size of the coupled inductance to be achieved, determine the number of series required for the coupled inductance; (5) According to the coupling coefficient relationship of the toroidal core under different reluctance and different turns of the winding, determine the size of the toroidal core and the number of turns of the winding for each toroidal coupling inductor.