Multi-interleaved parallel three-level DCDC device based on coupling inductor and control method

Abstract

The invention provides a multi-interleaving three-level DCDC device based on a coupling inductor and a control method, the device comprises a plurality of interleaving three-level conversion bridge arms, each bridge arm is divided into an upper half bridge arm and a lower half bridge arm according to a central line, and the upper half bridge arm and the lower half bridge arm are respectively connected with a coupling inductor module; the coupling inductor module comprises more than two coupling inductors, each coupling inductor comprises a magnetic core middle column, a plurality of wrapping posts and windings, the number of turns of the windings is equal, the winding directions of the windings are the same, and the wrapping posts are uniformly distributed around the magnetic core middle columns; and the control module is used for generating a carrier signal according to a preset phase shift angle so as to adjust the switching time of each bridge arm and realize the minimization of current ripples. The system has the advantages of being low in inductive current ripple, high in working efficiency and the like, efficiency, reliability and electromagnetic compatibility of the system can be remarkably improved, the system is more compact, and the system is suitable for various high-efficiency power electronic application occasions.

Description

A multi-interleaved parallel three-level DC-DC device and control method based on coupled inductors Technical Field

[0001] This invention relates to the field of power electronics technology, specifically to a multi-interleaved parallel three-level DC-DC device and control method based on coupled inductors. Background Technology

[0002] With the rapid development of the electrochemical energy storage industry, bidirectional DC-DC converters have attracted widespread attention due to their ability to achieve precise management of battery clusters. These devices not only allow for flexible switching between charging and discharging but also improve the overall efficiency and reliability of energy storage systems. Currently, in energy storage applications, bidirectional DC-DC converters typically employ a multi-level, interleaved parallel three-level circuit topology. Compared to traditional two-level circuits, three-level circuits offer advantages such as lower voltage stress on power devices, higher output waveform quality, and lower EMI (electromagnetic interference) levels. Furthermore, the multi-level, interleaved parallel connection of bridge arms effectively reduces input and output current ripple, further improving the device's power density.

[0003] However, despite the many benefits of multi-layered circuit design, there are also some problems that cannot be ignored. As the degree of multi-layering increases, the number of chopper inductors also increases. This not only increases the size and cost of the system, but also increases the current ripple of the chopper inductors, which in turn increases the total inductor losses and ultimately affects the overall efficiency of the system. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a multi-interleaved parallel three-level DC-DC device and control method based on coupled inductors with low inductor current ripple and high operating efficiency, in response to the above-mentioned problems of the prior art.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0006] A multi-interleaved parallel three-level DC-DC device based on coupled inductors, comprising:

[0007] Multiple interleaved parallel three-level conversion bridge arms, each bridge arm is divided into an upper half bridge arm and a lower half bridge arm according to the midline, and the upper half bridge arm and the lower half bridge arm are respectively connected to the coupled inductor module;

[0008] A coupled inductor module includes two or more coupled inductors. Each coupled inductor includes a magnetic core column, multiple winding columns, and windings. Each winding has the same number of turns and the same winding direction. The winding columns are evenly distributed around the magnetic core column.

[0009] The control module is used to generate a carrier signal according to a preset phase shift angle to adjust the switching time of each bridge arm and minimize current ripple.

[0010] As a further improvement to the method of the present invention: the center interval angle of each winding post in the coupled inductor is equal, and the interval angle θ is:

[0011]

[0012] Where N represents the total number of bridge arms.

[0013] As a further improvement to the method of the present invention: the winding posts in the coupled inductor have the same length and the center of each winding post is equidistant from the center of the magnetic core post.

[0014] As a further improvement to the method of the present invention: the magnetic core column in the coupled inductor module has an air gap, and the air gaps are of equal size.

[0015] As a further improvement to the method of the present invention: the winding is connected to the output of the upper half of the bridge arm and the lower half of the bridge arm respectively, so as to realize magnetic flux coupling between multiple bridge arms.

[0016] As a further improvement to the method of the present invention: the control module performs complementary control on the IGBT switching state within the half-bridge arm through a carrier signal, and controls different half-bridge arms through carrier phase shift. The carrier phase shift is achieved by the control module randomly numbering the half-bridge arms and generating corresponding phase shift angles based on the half-bridge arm numbers.

[0017] As a further improvement to the method of the present invention: the phase shift angle α of each half-arm is calculated using the following formula:

[0018]

[0019] Where N represents the total number of bridge arms, and m represents the half-bridge arm number.

[0020] This invention further provides a multi-interleaved parallel three-level DC-DC control method based on coupled inductors, comprising:

[0021] Step S1: Randomly number the multiple bridge arms in the device and subdivide each bridge arm into an upper bridge arm and a lower bridge arm;

[0022] The upper and lower halves of each bridge arm are numbered.

[0023] Step S2: Generate the corresponding phase shift angle according to the half-bridge number, and control the IGBT switching state in each half-bridge through the carrier signal to minimize the current ripple.

[0024] As a further improvement to the method of the present invention: in step S2, the control of the IGBT switching state in each half-bridge by carrier signal includes: performing complementary control of the IGBT switching state in the half-bridge arm by a carrier signal, and controlling different half-bridge arms by carrier phase shift. The carrier phase shift is achieved by the control module randomly numbering the half-bridge arms and generating corresponding phase shift angles according to the half-bridge arm numbers.

[0025] As a further improvement to the method of the present invention: the functional expression for generating the corresponding phase shift angle α based on the half-bridge number is:

[0026]

[0027] Where N represents the total number of bridge arms, and m represents the half-bridge arm number.

[0028] Compared with the prior art, the advantages of the present invention are as follows:

[0029] 1. This invention achieves several improvements, such as reduced current ripple, reduced inductor size, and guaranteed consistency of self-inductance and mutual inductance, through carrier phase-shift control method and optimized coupled inductor design. These improvements significantly enhance the system's efficiency, reliability, and electromagnetic compatibility, making the system more compact and suitable for various high-efficiency power electronics applications.

[0030] 2. This invention replaces multiple independent inductors in the prior art with a coupled inductor module, effectively reducing the volume of the inductor core, thereby reducing the inductor volume, simplifying the system structure, and reducing cost and volume; and by setting consistent winding column length, number of winding turns and air gap size, the consistency of self-inductance of each winding of the coupled inductor is achieved, thereby optimizing magnetic flux distribution and current ripple.

[0031] 3. The present invention further sets the distance from each winding post to the central post of the magnetic core to be consistent, so as to ensure the consistency of mutual inductance and thus avoid uneven current between the heavy bridge arms due to inconsistent inductance parameters. Attached Figure Description

[0032] Figure 1 is a circuit topology diagram of a multi-interleaved parallel three-level DC-DC device according to an embodiment of the present invention.

[0033] Figure 2 is a schematic diagram of the coupled inductor structure according to an embodiment of the present invention.

[0034] Figure 3 is a schematic diagram of the DC-DC half-bridge numbering in an embodiment of the present invention.

[0035] Figure 4 is a circuit topology diagram of a two-fold interleaved parallel three-level DC-DC device according to an embodiment of the present invention.

[0036] Figure 5 is a numbering diagram of two interleaved parallel three-level DC-DC converters in a specific application embodiment of the present invention.

[0037] Figure 6 is a diagram showing the relationship between the half-bridge carrier signals and the switching state of the main control tube in each embodiment of the present invention.

[0038] Figure 7 is a schematic diagram of the inductor current ripple in an embodiment of the present invention.

[0039] Figure 8 is a schematic diagram of the structure of a double-interleaved parallel three-level DC-DC coupled inductor according to an embodiment of the present invention.

[0040] Figure 9 is a schematic diagram of the reverse-coupled inductor magnetic circuit model according to an embodiment of the present invention.

[0041] Figure 10 is a flux diagram of the winding post and the central post of the magnetic core according to an embodiment of the present invention.

[0042] Legend:

[0043] 101. Upper yoke; 102. Lower yoke; 103. Core post; 104. Winding post; 105. Winding. Detailed Implementation

[0044] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0045] This embodiment discloses a multi-interleaved parallel three-level DC-DC device based on coupled inductors, comprising:

[0046] Multiple interleaved parallel three-level conversion bridge arms, each bridge arm is divided into upper half bridge arm and lower half bridge arm according to the midline, and the upper half bridge arm and lower half bridge arm are respectively connected to the coupled inductor module;

[0047] The coupled inductor module includes two or more coupled inductors. Each coupled inductor includes a magnetic core post 103, multiple winding posts 104, and windings 105. Each winding 105 has the same number of turns and the same winding direction. The winding posts 104 are evenly distributed around the magnetic core post 103.

[0048] The control module is used to generate a carrier signal according to a preset phase shift angle to adjust the switching time of each bridge arm and minimize current ripple.

[0049] In this embodiment, the windings of the coupled inductor have the same number of turns and the same winding direction, resulting in opposite magnetic fluxes. This creates a canceling effect in the magnetic core, ensuring that under the same input conditions, the magnetic fluxes generated by each winding cancel each other out, thereby reducing the overall rate of change of magnetic flux and thus reducing current ripple. Furthermore, the reverse-coupled inductor can better optimize the energy storage process and reduce energy loss. Because the magnetic fluxes cancel each other out, energy loss in the magnetic core can be reduced to a certain extent, improving system efficiency.

[0050] As shown in Figure 1, in a specific application embodiment, the multi-interleaved parallel three-level DC-DC circuit consists of N bridge arms, one coupling inductor, and three sets of capacitors. Each bridge arm includes four IGBTs, and the midpoint of each bridge arm is directly connected to the midpoint of the input-side capacitor to achieve three-level output. Based on the midline, each bridge arm can be divided into an upper half-bridge arm and a lower half-bridge arm, with the outputs of the upper and lower half-bridge arms respectively connected to the coupling inductor. When current flows from the Uin side to the Uout side, the DC-DC device operates in buck mode; when current flows from the Uout side to the Uin side, the DC-DC device operates in boost mode.

[0051] As shown in Figure 2, the coupling inductor in this embodiment also includes an upper yoke 101 and a lower yoke 102. It can be understood that the shapes of the upper yoke 101 and lower yoke 102 can be arbitrarily set according to actual needs. In this embodiment, the upper yoke 101 and lower yoke 102 are cylindrical. The winding posts 105 and the core posts 104 can be cylindrical or regular polygons, and the number of winding posts 104 is twice the number of bridge arms. The center-to-center spacing angle of each winding post 104 in the coupling inductor is equal, and the spacing angle θ is:

[0052]

[0053] Where N represents the total number of bridge arms.

[0054] In this embodiment, the winding posts 104 in the coupled inductor have the same length and the center of each winding post 104 is equidistant from the center of the magnetic core post 103.

[0055] In this embodiment, the magnetic core column 103 in the coupled inductor module has an air gap, and the air gaps are of equal size.

[0056] In this embodiment, the winding 105 is connected to the output of the upper half of the bridge arm and the lower half of the bridge arm respectively, so as to realize magnetic flux coupling between multiple bridge arms.

[0057] In this embodiment, the control module performs complementary control on the IGBT switching state within the half-bridge arm through a carrier signal, and controls different half-bridge arms through carrier phase shift. The carrier phase shift is achieved by the control module randomly numbering the half-bridge arms and generating the corresponding phase shift angle based on the half-bridge arm number.

[0058] Specifically, first, each bridge arm in the DC-DC circuit is numbered. There is no specific rule for numbering; only the number of each bridge arm needs to be determined. For example, they can be numbered as bridge arm 1, bridge arm 2, 3, ..., bridge arm N. Then, each bridge arm is further divided into upper and lower half-bridge arms. Simultaneously, either the upper or lower half-bridge arm of bridge arm 1 is selected as half-bridge 1. If the upper half-bridge arm of bridge arm 1 is selected as half-bridge 1, then its lower half-bridge arm is half-bridge 2. Then, for bridge arm n (where n is the bridge arm number), the upper half-bridge arm is numbered as half-bridge (2n-1), and the lower half-bridge arm is numbered as half-bridge 2n, as shown in Figure 3. If the lower half-bridge arm of bridge arm 1 is selected as half-bridge 1, then its upper half-bridge arm is half-bridge 2. Then, for bridge arm n (where n is the bridge arm number), the lower half-bridge arm is numbered as half-bridge (2n-1), and the upper half-bridge arm is numbered as half-bridge 2n.

[0059] In this embodiment, the phase shift angle α of each half-bridge arm is calculated using the following formula based on the half-bridge arm number:

[0060]

[0061] Where N represents the total number of bridge arms, and m represents the half-bridge arm number.

[0062] The following describes this application in detail using a two-stage interleaved parallel three-level DC-DC device as an example:

[0063] As shown in Figure 4, this embodiment consists of 8 IGBTs, one coupling inductor, and three sets of capacitors; wherein, the 8 IGBT devices Sa1, Sa2, Sa3, and Sa4 form one bridge arm, and Sb1, Sb2, Sb3, and Sb4 form another bridge arm.

[0064] As shown in Figure 5, each half-bridge is numbered in this embodiment:

[0065] 1) Randomly number the two bridge arms, namely bridge arm 1 and bridge arm 2;

[0066] 2) If the upper half of bridge arm 1 is selected as half bridge 1, then the lower half of bridge arm 1 is half bridge 2, the upper half of bridge arm 2 is half bridge 3, and the lower half of bridge arm 2 is half bridge 4.

[0067] 3) Since the switching states of the two IGBTs within each half-bridge are complementary, control can be achieved through a single carrier wave. For different half-bridges, control is achieved through carrier phase shifting, with each half-bridge having a phase shift angle of 90*(m-1), where m is the half-bridge number. For ease of description, assume that Sa1, Sa4, Sb1, and Sb4 are the master control transistors in their respective half-bridges. When the duty cycle D is in the range of 0.5 < D < 0.75, the relationship between the carrier signals of the four half-bridges and the switching states of each master control transistor within one carrier cycle can be obtained, as shown in Figure 6, where Txy (x represents a and b, y represents 1 and 4) represents the carrier signals of each half-bridge.

[0068] In practical applications, a simulation model was built using the above-mentioned multi-interleaved parallel three-level DC-DC device based on coupled inductors and its control method to compare the inductor current ripple size of the control method proposed in this patent with that of the traditional control method. The specific ripple is shown in Figure 7. The multi-interleaved parallel three-level DC-DC device based on coupled inductors proposed in this application can effectively reduce the inductor current ripple.

[0069] In this embodiment, the coupled inductor structure of the double-interleaved parallel three-level DC-DC device is shown in Figure 8. It has four winding posts, symmetrical about the center of the magnetic core. The distance *d* from the center of each winding post to the center of the magnetic core is equal, the air gaps are equal in size, and the center-to-center angle of each winding post is 90°. There are four windings, each with the same number of turns and the same winding direction, producing opposite magnetic fluxes, forming a reverse-coupled inductor.

[0070] Based on the above core structure, the reverse-coupled inductor magnetic circuit model can be obtained as shown in Figure 9, where M is the number of coil turns, and i j (j is the half-bridge number) represents the winding current, R is the reluctance of the winding column, and R1 is the reluctance of the core column. It can be seen that the self-inductance and mutual inductance of each winding are equal, ensuring the consistency of the winding parameters.

[0071] Based on the aforementioned control method, the magnetic flux of the winding post and the core post is plotted according to the changes in current and voltage of each winding, as shown in Figure 10. Therefore, by adopting the control method described in this paper, the alternating magnetic flux of the core post can be effectively reduced, thereby reducing the volume of the core post.

[0072] This embodiment also provides a multi-interleaved parallel three-level DC-DC control method based on coupled inductors, including:

[0073] Step S1: Randomly number the multiple bridge arms in the device and subdivide each bridge arm into an upper bridge arm and a lower bridge arm;

[0074] The upper and lower halves of each bridge arm are numbered.

[0075] Step S2: Generate the corresponding phase shift angle according to the half-bridge number, and control the IGBT switching state in each half-bridge through the carrier signal to minimize the current ripple.

[0076] In step S2 of this embodiment, controlling the IGBT switching state in each half-bridge via a carrier signal includes: performing complementary control of the IGBT switching state in each half-bridge arm via a carrier signal, and controlling different half-bridge arms via carrier phase shift. The carrier phase shift is achieved by the control module randomly numbering the half-bridge arms and generating corresponding phase shift angles based on the half-bridge arm numbers.

[0077] The function expression for generating the corresponding phase shift angle α based on the half-bridge number is:

[0078]

[0079] Where N represents the total number of bridge arms, and m represents the half-bridge arm number.

[0080] This embodiment effectively reduces inductor current ripple and inductor loss by using carrier phase-shift control, thereby improving the efficiency of DC-DC converters. The coupling inductor, in conjunction with carrier phase-shift control, effectively reduces the alternating magnetic flux in the core pillars, thus reducing the volume of the core pillars. Furthermore, the coupling inductor, through a reasonable magnetic circuit design, ensures the consistency of self-inductance and mutual inductance among the windings, avoiding uneven current distribution caused by inconsistent inductance parameters. This significantly improves the system's efficiency, reliability, and electromagnetic compatibility, making the system more compact and suitable for various high-efficiency power electronics applications.

[0081] The above description is merely a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A multi-interleaved parallel three-level DC-DC device based on coupled inductors, characterized in that, include: Multiple interleaved parallel three-level conversion bridge arms, each bridge arm is divided into an upper half bridge arm and a lower half bridge arm according to the center line, and the upper half bridge arm and the lower half bridge arm are respectively connected to the coupling inductor module; the coupling inductor module includes two or more coupling inductors, each coupling inductor includes a magnetic core column (103), multiple winding columns (104), and windings (105), each winding (105) has the same number of turns and the same winding direction, and the winding columns (104) are evenly distributed around the magnetic core column (103); the control module is used to generate a carrier signal according to a preset phase shift angle to adjust the switching time of each bridge arm and minimize the current ripple.

2. The multi-interleaved parallel three-level DC-DC device based on coupled inductors according to claim 1, characterized in that, The centers of each winding post (104) in the coupled inductor are spaced at equal angles, and the spacing angle θ is: Where N represents the total number of bridge arms.

3. The multi-interleaved parallel three-level DC-DC device based on coupled inductors according to claim 1, characterized in that, In the coupled inductor, each winding post (104) has the same length and the center of each winding post (104) is equidistant from the center of the magnetic core post (103).

4. The multi-interleaved parallel three-level DC-DC device based on coupled inductors according to any one of claims 1 to 3, characterized in that, The magnetic core column (103) in the coupled inductor module has an air gap, and the air gaps are of equal size.

5. The multi-interleaved parallel three-level DC-DC device based on coupled inductors according to any one of claims 1 to 3, characterized in that, The winding (105) is connected to the output of the upper half of the bridge arm and the lower half of the bridge arm respectively, so as to realize magnetic flux coupling between multiple bridge arms.

6. The multi-interleaved parallel three-level DC-DC device based on coupled inductors according to claim 1, characterized in that, The control module performs complementary control on the IGBT switching state within the half-bridge arm via a carrier signal, and controls different half-bridge arms by carrier phase shift. The carrier phase shift is achieved by the control module randomly numbering the half-bridge arms and generating corresponding phase shift angles based on the half-bridge arm numbers.

7. The multi-interleaved parallel three-level DC-DC device based on coupled inductors according to claim 6, characterized in that, The phase shift angle α of each half-arm is calculated using the following formula: Where N represents the total number of bridge arms, and m represents the half-bridge arm number.

8. A multi-interleaved parallel three-level DC-DC control method based on coupled inductors, characterized in that, include: Step S1: Randomly number the multiple bridge arms in the device, and subdivide each bridge arm into an upper half bridge arm and a lower half bridge arm; and number the upper half bridge arm and the lower half bridge arm in each bridge arm; Step S2: Generate the corresponding phase shift angle according to the half bridge number, and control the IGBT switching state in each half bridge through a carrier signal to minimize the current ripple.

9. The multi-interleaved parallel three-level DC-DC control method based on coupled inductors according to claim 8, characterized in that, In step S2, controlling the IGBT switching state within each half-bridge via a carrier signal includes: performing complementary control of the IGBT switching state within each half-bridge arm via a carrier signal, and controlling different half-bridge arms via carrier phase shift. The carrier phase shift is achieved by the control module randomly numbering the half-bridge arms and generating corresponding phase shift angles based on the half-bridge arm numbers.

10. The multi-interleaved parallel three-level DC-DC control method based on coupled inductors according to claim 9, characterized in that, The function expression for generating the corresponding phase shift angle α based on the half-bridge number is: Where N represents the total number of bridge arms, and m represents the half-bridge arm number.

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