A multi-port converter and control method

Abstract

The application discloses a multi-port converter and a control method. The converter comprises N ports, N bridge arm circuits, an N-port transformer and a controller, wherein N is an integer greater than or equal to 3; each bridge arm circuit comprises at least two bridge arms; the N-port transformer comprises N windings; the N windings and the N bridge arm circuits are in one-to-one correspondence; each winding in the N windings is connected to a corresponding bridge arm circuit; the controller controls the internal phase shift angle of the bridge arm circuit of the voltage mismatch port in the N ports to be zero, dynamically adjusts the internal phase shift angle and the external phase shift angle of each port based on preset electrical parameters of each port, and the electrical parameters are at least one of the following: voltage, current or power; the internal phase shift angle is the phase angle difference between the switching tubes of the two bridge arms, the external phase shift angle is the phase angle difference between the switching tubes of the bridge arms of any two ports, the power of each port is independently controlled, the power of each port is decoupled, the control is simple, the problem of backflow power is efficiently solved, and the efficiency is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power electronics, in particular to a multi-port converter and a control method. BACKGROUND

[0002] A multi-port converter, such as a triple active bridge (TAB), has the advantages of high power density, flexible energy scheduling of each port, high efficiency, and the like, and has great application prospects in on-board chargers (OBCs), direct current power distribution networks, and photovoltaic storage and charging integrated systems.

[0003] When the multi-port converter is in operation, there is a large backflow power between each port, which affects the energy transmission efficiency, and this problem is particularly prominent when the port voltages are mismatched. In addition, since each port shares a magnetic core, there is a technical problem of power coupling between each port.

[0004] At present, in the efficiency optimization of a multi-port converter, for example, the efficiency optimization of a TAB, the technical idea mainly follows the optimization idea of a dual active bridge (DAB), that is, an accurate mathematical analytical expression of an electrical quantity to be optimized, such as power and current effective value, is obtained through piecewise linearization, and an optimal point is solved through a mathematical algorithm. This method needs complex derivation according to different phase-shift control modes, and modeling is difficult. Therefore, it is difficult to apply in engineering. SUMMARY

[0005] To solve the above problems, the present application provides a multi-port converter and a control method, which can efficiently solve the problems of backflow power and power decoupling, thereby improving efficiency.

[0006] The present application provides a multi-port converter, comprising: N ports, N bridge arm circuits, an N-port transformer, and a controller; N is an integer greater than or equal to 3; each bridge arm circuit comprises at least two bridge arms;

[0007] The N-port transformer comprises N windings; the N windings and the N bridge arm circuits are in one-to-one correspondence; each winding of the N windings is connected to a corresponding bridge arm circuit;

[0008] The controller is configured to control the inner phase-shift angle of the bridge arm circuit of the voltage mismatched port in the N ports to be zero, and dynamically adjust the inner phase-shift angle and the outer phase-shift angle of each port based on preset electrical parameters of each port, the electrical parameters being at least one of voltage, current, or power;

[0009] The inner phase-shift angle is the phase angle difference between the switching tubes of the two bridge arms, and the outer phase-shift angle is the phase angle difference between the switching tubes of the bridge arms of any two ports.

[0010] Preferably, when the preset electrical parameter is voltage, the controller is specifically configured to obtain the outwardly shifted phase angle and the inwardly shifted phase angle of the remaining N-1 ports according to the phase angle difference between the bridge arm midpoint voltage of the port i, the bridge arm midpoint voltage of the port j and the bridge arm midpoint voltage of the port i; j is the voltage mismatch port, and i is any one of the remaining N-1 ports.

[0011] Preferably, the controller is specifically configured to obtain the outwardly shifted phase angle and the inwardly shifted phase angle of the remaining N-1 ports according to the following preset condition:

[0012] The preset condition includes that the bridge arm midpoint voltage amplitude of the port i multiplied by cos(Ψ ij ) is equal to the bridge arm midpoint voltage amplitude of the port j, Ψ ij is the phase angle difference between the bridge arm midpoint voltage of the port i and the bridge arm midpoint voltage of the port j.

[0013] Preferably, the preset condition specifically includes that the fundamental component amplitude of the bridge arm midpoint voltage of the port i multiplied by cos(Ψ ij ) is equal to the fundamental component amplitude of the bridge arm midpoint voltage of the port j, Ψ ij is the phase angle difference between the bridge arm midpoint voltage of the port i and the bridge arm midpoint voltage of the port j.

[0014] Preferably, the controller is further configured to convert the bridge arm input voltages of the N bridge circuits to the same port according to the transformation ratio of the N-port transformer, and the port with the minimum converted voltage is determined as the voltage mismatch port.

[0015] Preferably, the bridge circuit at least includes one of the following: a two-level topology or a multi-level topology.

[0016] Preferably, N is 3, the bridge circuit is an H-bridge full-bridge circuit, and the three ports included in the transformer are respectively used for connecting a direct current power supply, an energy storage battery and a load.

[0017] Preferably, the direct current power supply is a photovoltaic array.

[0018] The application also provides a power supply system, which includes the above-mentioned multi-port transformer.

[0019] The application also provides a control method of a multi-port transformer, the multi-port transformer including N ports, N bridge circuits, an N-port transformer and a controller; N is an integer greater than or equal to 3; the N-port transformer includes N windings; the N windings and the N bridge circuits are in one-to-one correspondence; each winding in the N windings is connected to a corresponding bridge circuit.

[0020] The method includes:

[0021] The inwardly shifted phase angle of the bridge circuit of the voltage mismatch port in the N ports is controlled to be zero;

[0022] The inner phase shift angle and the outer phase shift angle of each port are dynamically adjusted based on preset electrical parameters of each port, and the preset electrical parameters are at least one of voltage, current or power.

[0023] The inner phase shift angle is a phase angle difference between switch tubes of two bridge arms, and the outer phase shift angle is a phase angle difference between switch tubes of bridge arms of any two ports.

[0024] Preferably, when the preset electrical parameter is voltage, the inner phase shift angle and the outer phase shift angle of each port are dynamically adjusted based on the preset electrical parameters of each port, and specifically comprising:

[0025] The outer phase shift angle and the inner phase shift angle of the remaining N-1 ports are obtained according to the bridge arm midpoint voltage of port i, the bridge arm midpoint voltage of port j and the phase angle difference therebetween; j is a voltage mismatch port, and i is any one of the remaining N-1 ports.

[0026] Preferably, the outer phase shift angle and the inner phase shift angle of the remaining N-1 ports are obtained according to the bridge arm midpoint voltage of port i, the bridge arm midpoint voltage of port j and the phase angle difference therebetween, and specifically comprising:

[0027] The outer phase shift angle and the inner phase shift angle of the remaining N-1 ports are obtained according to the following preset conditions;

[0028] The preset conditions include that the amplitude of the bridge arm midpoint voltage of port i multiplied by cos(Ψ ij ) is equal to the amplitude of the bridge arm midpoint voltage of port j, and Ψ ij is the phase angle difference between the bridge arm midpoint voltage of port i and the bridge arm midpoint voltage of port j.

[0029] Preferably, the preset conditions include that the amplitude of the fundamental component of the bridge arm midpoint voltage of port i multiplied by cos(Ψ ij ) is equal to the amplitude of the fundamental component of the bridge arm midpoint voltage of port j, and Ψ ij is the phase angle difference between the bridge arm midpoint voltage of port i and the bridge arm midpoint voltage of port j.

[0030] Preferably, it further comprises: converting the bridge arm input voltage of the N bridge arm circuits to the same port according to the transformation ratio of the N-port transformer, and the port with the smallest converted voltage is determined as the voltage mismatch port.

[0031] Preferably, it further comprises: detecting the bridge arm input voltage of the N bridge arm circuits, and determining whether there is a voltage mismatch port according to the bridge arm input voltage of the N bridge arm circuits, if not, generating a PWM signal according to a preset working mode, and driving the switch tubes in the bridge arm circuit by using the PWM signal.

[0032] Therefore, the present application has the following beneficial effects:

[0033] The multi-port converter provided in the application sets the internal phase shift angle of the voltage mismatch port to zero, i.e. forces the voltage mismatch port to perform maximum power transmission, increases the port voltage, and makes the voltage mismatch port gradually exit the voltage mismatch state, so that active power is transmitted between the ports, the backflow power of each port is reduced, and the power conversion efficiency is improved. In addition, since the internal phase shift angle of the voltage mismatch port is fixed to zero, the internal phase shift angle and the external phase shift angle of the remaining ports can be obtained more simply, the calculation amount is effectively reduced, the power of each port can be independently controlled, the power of each port is decoupled, the control is simpler, the efficiency is higher, and the application in actual products is facilitated. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 is a schematic diagram of a three-port DCDC converter;

[0035] Figure 2 is a timing diagram of the driving signal of each switch tube and the bridge arm midpoint voltage provided by the embodiment of the application;

[0036] Figure 3 is a voltage phasor diagram provided by the embodiment of the application;

[0037] Figure 4 is a schematic diagram of a three-port DCDC converter provided by the embodiment of the application;

[0038] Figure 5 is a schematic diagram of a diode clamped type three-level full-bridge structure provided by the embodiment of the application;

[0039] Figure 6 is a schematic diagram of a three-level full-bridge structure with flying capacitor provided by the embodiment of the application;

[0040] Figure 7 is a schematic diagram of a T-type three-level full-bridge structure provided by the embodiment of the application;

[0041] Figure 8 is a schematic diagram of a three-port bidirectional DCDC converter composed of a diode clamped type three-level full-bridge structure provided by the embodiment of the application;

[0042] Figure 9 is a schematic diagram of a three-port bidirectional DCDC converter composed of bridge circuits with different structures provided by the embodiment of the application;

[0043] Figure 10 is a schematic diagram of a power supply system provided by the embodiment of the application;

[0044] Figure 11A is a flowchart of a control method of a multi-port bidirectional DCDC converter provided by the embodiment of the application;

[0045] Figure 11B Another flowchart of a control method of a multi-port bidirectional DCDC converter is provided for the embodiments of the present application.

[0046] Figure 12 A voltage and current waveform diagram before the application of the technical solution is provided for the embodiments of the present application.

[0047] Figure 13 A voltage and current waveform diagram after the application of the technical solution is provided for the embodiments of the present application. DETAILED DESCRIPTION

[0048] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the embodiments of the present application will be further described in detail below with reference to the drawings and specific embodiments.

[0049] The multi-port converter provided by the embodiments of the present application can be a multi-port isolated bidirectional DCDC converter, and energy can flow bidirectionally between multiple ports. The application scenarios are not specifically limited, and those skilled in the art can use them according to actual needs.

[0050] In order to make it easier for those skilled in the art to understand, the following will be introduced by taking three ports as an example, and the bridge arm circuit included in each port will be introduced by taking an H-bridge full-bridge circuit as an example. Moreover, the switches in the H-bridge full-bridge will be introduced by taking all of them as fully controlled switches as an example.

[0051] Referring to Figure 1 , the figure is a schematic diagram of a three-port DCDC converter.

[0052] For example, the three-port DCDC converter can be applied to a light storage and charging integrated system, for example, the first port is connected to a photovoltaic array, the second port is connected to an energy storage battery, and the third port is connected to a load, which can be charged for the load, etc. For example, it can be a charging pile. The transformer T includes three windings: a first winding, a second winding and a third winding, and the three windings share one magnetic core, and the turn ratio of the three windings is n1:n2:n3. The three windings correspond to the connection of the first H-bridge, the second H-bridge and the third H-bridge respectively.

[0053] The first port includes the first H-bridge, and the two bridge arms of the first H-bridge include four switches S1, S2, S3 and S4 in total. The inductor and one winding of the transformer are connected between the midpoint (a and b) of the two bridge arms of the first H-bridge, and the inductor of the first port is L1. The midpoint voltage of the bridge arm of the first H-bridge is represented by Vab, and the current of the first winding is i L1 .

[0054] The second port includes a second H-bridge, whose two arms comprise four switching transistors: Q1, Q2, Q3, and Q4. An inductor and a transformer winding are connected between the midpoints (c and d) of the two arms of the second H-bridge. The inductor at the second port is L2. The voltage at the midpoint of the second H-bridge arm is denoted by Vcd, and the current in the second winding is i. L2 .

[0055] The third port includes the third H-bridge, whose two arms comprise four switching transistors: B1, B2, B3, and B4. An inductor and a transformer winding are connected between the midpoints of the two arms of the third H-bridge. The inductor at the third port is L3. The midpoint voltage of the third H-bridge arm is denoted by Vef, and the current in the third winding is i. L3 .

[0056] It should be understood that since each port is a bidirectional port, the energy of the H-bridge can flow in both directions. However, for ease of description, the following explanation uses the midpoint voltage of the bridge arm as the output voltage. For example, V1 is the input voltage of the first H-bridge arm, V2 is the input voltage of the second H-bridge arm, and V3 is the input voltage of the third H-bridge arm. C1 is the input capacitor of the first H-bridge, C2 is the input capacitor of the second H-bridge, and C3 is the input capacitor of the third H-bridge.

[0057] To enable those skilled in the art to better understand the technical solutions provided in the embodiments of this application, the following is combined with... Figure 1 and Figure 2 Let me introduce some technical terms.

[0058] Figure 2 The PWM waveforms in the diagram represent the drive signals for the corresponding switching transistors. The PWM signals of S1 and S2 are complementary, as are the PWM signals of S3 and S4, Q1 and Q2, and B1 and B2. Complementarity means that the inverted versions of the PWM signals of S1 and S2 are the same.

[0059] Inner phase shift angle: The phase shift angle between the two arms of each H-arm, specifically the phase difference (phase angle difference) between the drive signals of the switching transistors of the two arms. As shown in Figure 2, the phase angle difference between S1 (or S3) and S4 (or S2) is defined as α; the phase angle difference between Q1 (or Q3) and Q4 (or Q2) is defined as β; and the phase angle difference between B1 (or B3) and B4 (or B2) is defined as γ.

[0060] Outer phase shift angle: The phase shift angle between the two ports of the H-bridge. For example... Figure 2 As shown, the phase angle difference between S1 (or S4) and Q1 (or Q3) is defined as δ. 12 The phase angle difference between Q1 and B1 is defined as δ. 23 The phase angle difference between B1 and S1 is defined as δ.31 .

[0061] The phase angle difference of the bridge arm midpoint voltage of each port H bridge, i.e. the square wave voltage, is defined as Ψ 12 , Ψ 23 , Ψ 31 , when the inner phase shift angle in each port is 0, i.e. equal to the outer phase shift angle δ 12 , δ 23 , δ 31 .

[0062] The relationship between the inner phase shift angle, the outer phase shift angle and the phase angle difference of the bridge arm midpoint voltage can be seen from Figure 2 .

[0063] In order for those skilled in the art to better understand the technical solutions provided by the present application, the derivation process of the technical solutions provided by the embodiments of the present application is introduced first.

[0064] Referring to Figure 3 , the figure is a voltage phasor diagram provided by the present application.

[0065] Figure 3 It includes two figures, i.e. (a) and (b).

[0066] The phase difference between the bridge arm midpoint voltages V ab , V cd , V ef of each H bridge is represented by Ψ 12 , Ψ 12 , Ψ 31 , which is converted to the first port, and rewritten as V ab , V′ cd1 , V′ ef1 , which can be Fourier series decomposed, combined with Figure 2 The expression of active power transmission between each port can be written as shown in formula (1).

[0067]

[0068] Among them, V 11 = V1, V 22 = n1V2 / n2, V 33 = n1V3 / n3.

[0069] The fundamental component phasor diagram of the bridge arm midpoint voltages V ab , V cd , V ef of each H bridge is drawn, with the direction of Vab1 as the reference direction, as shown in Figure 3As shown, at this time, the second port is in a voltage mismatch state (V2 is lower than the value after conversion of the transformer ratio), at this time, the converter will have a larger backflow power. At this time, the areas of the triangle ABD and the triangle ACD can be represented by formula (2), and it is found that the areas of the triangle ABD and the triangle ACD respectively represent the active power transmitted between the first port and the second port.

[0070]

[0071] In order to reduce the reactive power at this time, it is observed that Figure 3 (a), and it is found that when V' cd1 , V ab1 and V' ef1 form a right triangle, that is, B, C and D are located on the same straight line, the reactive power of the converter is the smallest, because at this time, I 23 , I 12 and V' cd1 are in phase, and the reactive power is eliminated.

[0072] If the loss is further reduced, the effective value of the inductance current should be reduced, and when the active power is constant, for two right triangles, when the common side V' cd1 takes the maximum value, the height of the triangle is the shortest, that is, the inductance current takes the minimum value, and the efficiency is further optimized. When the relationship of the triangle Figure 3 (b) occurs, the area of the triangle ABC can also represent the active power transmitted between the first port and the third port, and there is a power equation relationship as shown in formula (3), and the original power relationship is as follows: P1=P 12 -P 31 , P2=P 12 +P 23 , P3=P 23 +P 31 , after formula (3) is added, the power relationship of each port is simplified to formula (4).

[0073] P 31 =P 12 +P 23 (3)

[0074]

[0075] At this time, the active power of each port in the converter can be independently adjusted, the power P1 of the first port is only controlled by the phase difference between the second port and the third port, and the power P3 of the third port is only controlled by the phase difference between the first port and the second port, thereby realizing power decoupling control.

[0076] Similarly, the third harmonic, the fifth harmonic and higher harmonic components can be analyzed.

[0077] For the convenience of understanding, only the constraint condition based on the fundamental component is introduced below, see formula (5).

[0078]

[0079] Since the internal phase shift angle of the voltage mismatch port has been set to 0, only 4 unknowns need to be solved in formula (5).

[0080] From the above description, the constraint condition at this time is shown in formula (5), including power instruction constraints, two right triangle side length constraints, and the range constraints of each internal and external phase shift angle. The constraint condition expression has simple and clear physical meaning, and can be solved by using any optimization algorithm.

[0081] Based on the above derivation and analysis, the multi-port converter provided by the embodiments of the present application is introduced below.

[0082] The multi-port converter provided by the embodiments of the present application comprises N ports, N bridge arm circuits, an N-port transformer and a controller; N is an integer greater than or equal to 3; each bridge arm circuit comprises at least two bridge arms.

[0083] Referring to Figure 4 , the figure is a schematic diagram of a three-port converter provided by the embodiments of the present application.

[0084] The three-port converter comprises a bridge arm circuit 401, a bridge arm circuit 402 and a bridge arm circuit 403.

[0085] The embodiments of the present application do not specifically limit the specific topology of the bridge arm circuit, for example, the bridge arm circuit at least comprises one of the following: a two-level topology or a multi-level topology. Figure 1 The two-level H-bridge topology structure is shown.

[0086] In addition to the two-level topology shown Figure 1 , the bridge arm circuit can also be the following bridge arm circuit, for example Figure 5 , the diode clamped type three-level full-bridge structure, Figure 6 , the three-level full-bridge structure with flying capacitor. Figure 7 , the T-type three-level full-bridge structure. Figure 8 , the three-port bidirectional DCDC converter composed of the diode clamped type three-level full-bridge structure. Figure 9 , the three-port bidirectional DCDC converter composed of bridge circuits with different structures.

[0087] The N-port transformer comprises N windings; the N windings and the N bridge arm circuits are in one-to-one correspondence; each winding in the N windings is connected to a corresponding bridge arm circuit;

[0088] The controller is configured to control the inner phase shift angle of the bridge arm circuit of the voltage mismatch port in the N ports to be zero, dynamically adjust the inner phase shift angle and the outer phase shift angle of each port based on preset electrical parameters of each port, and the preset electrical parameters are at least one of voltage, current or power.

[0089] The above formula (5) can be used to solve the equation according to the actual detection of each electrical parameter to obtain each inner phase shift angle and outer phase shift angle, or the inner phase shift angle and the outer phase shift angle corresponding to each voltage can be obtained in advance through experiments and stored in the converter as preset electrical parameters. During actual operation, the preset electrical parameters can be directly obtained through data query.

[0090] The multi-port converter provided in the application sets the inner phase shift angle of the voltage mismatch port to zero, that is, forces the voltage mismatch port to perform maximum power transmission, increases the port voltage, and gradually exits the voltage mismatch state, so that active power is transmitted between each port, the backflow power of each port is reduced, and the power conversion efficiency is improved. In addition, since the inner phase shift angle of the voltage mismatch port is fixed to zero, the inner phase shift angle and the outer phase shift angle of the remaining ports can be obtained more simply, the calculation amount is effectively reduced, and the power of each port can be independently controlled, the power of each port is decoupled, the control is simpler, the efficiency is higher, and the application in actual products is facilitated.

[0091] The inner phase shift angle is the phase angle difference between the switch tubes of the two bridge arms, and the outer phase shift angle is the phase angle difference between the switch tubes of the bridge arms of any two ports.

[0092] It should be understood that the voltage mismatch port can be determined in the following manner: the bridge arm input voltages of each port are detected in real time, the bridge arm input voltages are V1, V2 and V3 as shown in the figure, that is, the controller is also used to convert the bridge arm input voltages of the N bridge arm circuits to the same port according to the transformation ratio of the N-port transformer, and the port with the smallest voltage after conversion is determined as the voltage mismatch port. If the voltages of each port are the same after conversion, it means that there is no voltage mismatch port, and then the PWM signal is generated according to the preset working mode, and the switch tube in the bridge arm circuit is driven by using the PWM signal. Figure 1

[0093] When the electrical parameter is voltage, the controller is specifically configured to obtain the outer phase shift angle and the inner phase shift angle of the remaining N-1 ports according to the phase angle difference between the bridge arm midpoint voltage of port i and the bridge arm midpoint voltage of port j; j is the voltage mismatch port, and i is any one of the remaining N-1 ports.

[0094] The following describes a method applicable to both fundamental components and any harmonic components.

[0095] The controller is specifically configured to obtain the outer phase shift angle and the inner phase shift angle of the remaining N-1 ports according to the following preset conditions: ​

[0096] The preset condition includes: the amplitude of the bridge arm midpoint voltage of the port i multiplied by cos(Ψ ij ) is equal to the amplitude of the bridge arm midpoint voltage of the port j, and Ψ ij is the phase angle difference between the bridge arm midpoint voltage of the port i and the bridge arm midpoint voltage of the port j.

[0097] The applicable mode for the fundamental component is introduced below.

[0098] The preset condition specifically includes: the amplitude of the fundamental component of the bridge arm midpoint voltage of the port i multiplied by cos(Ψ ij ) is equal to the amplitude of the fundamental component of the bridge arm midpoint voltage of the port j, and Ψ ij is the phase angle difference between the bridge arm midpoint voltage of the port i and the bridge arm midpoint voltage of the port j.

[0099] A specific application scenario is that N is 3 in the multi-port converter, that is, three ports, and the bridge arm circuit is an H-bridge full-bridge circuit; the three ports are respectively used for connecting a direct-current power supply, an energy storage battery and a load.

[0100] When applied to a photovoltaic system, the direct-current power supply is a photovoltaic array, that is, the first port can be directly connected to a photovoltaic string.

[0101] Based on the multi-port converter provided in the above embodiment, the embodiment of the present application further provides a power supply system, which will be described in detail below with reference to the accompanying drawings.

[0102] Referring to Figure 10 , the figure is a schematic diagram of a power supply system provided by the embodiment of the present application.

[0103] The power supply system provided by the embodiment includes the multi-port converter introduced above.

[0104] Taking the multi-port converter 101 as a three-port bidirectional DCDC converter as an example, the power supply system can further include a direct-current power supply 102, an energy storage battery 103 and a load 104, for example, one port of the multi-port converter 101 is connected to the direct-current power supply 102, and the direct-current power supply 102 can be derived from a photovoltaic array or other converters. Another port is connected to the energy storage battery 103, and another port is connected to the load 104. For example, the direct-current power supply 102 can be converted by the multi-port converter 101 to charge the energy storage battery 103, or can be converted by the multi-port converter 101 to charge the load. Moreover, the power supply system can also continue to supply power to the load 104 by the energy storage battery 103 when the direct-current power supply 102 is powered off or has a low voltage.

[0105] The power supply system provided by the embodiment of the present application has high efficiency and low loss, and is beneficial to protecting the electrical elements, because the power supply system includes the multi-port converter as described above, and the multi-port converter can quickly adjust the voltage of the voltage mismatch port to normal, thereby efficiently transmitting active power between the ports, reducing the backflow power of each port, and improving the power conversion efficiency.

[0106] Based on the multi-port converter and the power supply system provided in the above embodiment, the embodiment of the present application further provides a control method of the multi-port converter, which will be described in detail below with reference to the drawings.

[0107] Referring to Figure 11A FIG. 3 is a flowchart of a control method of a multi-port converter provided by the embodiment of the present application.

[0108] The control method of the multi-port converter provided by the embodiment is applied to a multi-port converter including N ports, N bridge arm circuits, an N-port transformer and a controller; N is an integer greater than or equal to 3; the N-port transformer includes N windings; the N windings and the N bridge arm circuits are in one-to-one correspondence; each winding of the N windings is connected to a corresponding bridge arm circuit;

[0109] The method includes the following steps.

[0110] S1101: controlling the internal phase shift angle of the bridge arm circuit of the voltage mismatch port in the N ports to be zero.

[0111] S1102: dynamically adjusting the internal phase shift angle and the external phase shift angle of each port based on preset electrical parameters of each port, and the electrical parameter reference value being at least one of the following: voltage, current or power.

[0112] The internal phase shift angle is the phase angle difference between the switch tubes of the two bridge arms, and the external phase shift angle is the phase angle difference between the switch tubes of the bridge arms of any two ports.

[0113] When the electrical parameter is voltage, dynamically adjusting the internal phase shift angle and the external phase shift angle of each port based on preset electrical parameters of each port specifically includes the following steps.

[0114] According to the bridge arm midpoint voltage of the port i, the bridge arm midpoint voltage of the port j and the phase angle difference therebetween, the external phase shift angle and the internal phase shift angle of the remaining N-1 ports are obtained; j is the voltage mismatch port, and i is any one of the remaining N-1 ports.

[0115] The following describes obtaining the external phase shift angle and the internal phase shift angle according to the fundamental wave and harmonic components of the bridge arm midpoint voltage.

[0116] According to the bridge arm midpoint voltage of the port i, the bridge arm midpoint voltage of the port j and the phase angle difference therebetween, the external phase shift angle and the internal phase shift angle of the remaining N-1 ports are obtained, specifically including the following steps.

[0117] The outer displacement phase angle and the inner displacement phase angle of the remaining N-1 ports are obtained according to the following preset condition;

[0118] The preset condition includes that the bridge arm midpoint voltage amplitude of the port i multiplied by cos(Ψ ij ) is equal to the bridge arm midpoint voltage amplitude of the port j, and Ψ ij is the phase angle difference between the bridge arm midpoint voltage of the port i and the bridge arm midpoint voltage of the port j.

[0119] The following introduces the outer displacement phase angle and the inner displacement phase angle obtained according to the fundamental component of the bridge arm midpoint voltage.

[0120] The preset condition includes that the fundamental component amplitude of the bridge arm midpoint voltage of the port i multiplied by cos(Ψ ij ) is equal to the fundamental component amplitude of the bridge arm midpoint voltage of the port j, and Ψ ij is the phase angle difference between the bridge arm midpoint voltage of the port i and the bridge arm midpoint voltage of the port j.

[0121] The control method provided in the embodiments of the present application further includes: converting the bridge arm input voltages of the N bridge arm circuits to the same port according to the transformation ratio of the N-port transformer, and determining the port with the minimum converted voltage as the voltage mismatch port.

[0122] The control method provided in the embodiments of the present application further includes: detecting the bridge arm input voltages of the N bridge arm circuits, judging whether there is a voltage mismatch port according to the bridge arm input voltages of the N bridge arm circuits, generating a PWM signal according to the preset working mode if there is no voltage mismatch port, and driving the switching tubes in the bridge arm circuit by using the PWM signal.

[0123] The following introduces a specific implementation mode of the control method provided in the embodiments of the present application.

[0124] Referring to Figure 11B , the figure is a flow chart of another control method of a multi-port converter provided in the embodiments of the present application.

[0125] S1201: detecting the bridge arm input voltages of the N bridge arm circuits;

[0126] S1202: judging whether there is a voltage mismatch port according to the bridge arm input voltages of the N bridge arm circuits; if yes, performing S1203, and if no, performing S1206;

[0127] S1203: controlling the inner displacement phase angle of the bridge arm circuit of the voltage mismatch port in the N ports to be zero;

[0128] S1204: obtaining the inner displacement phase angle and the outer displacement phase angle of each port according to the preset condition;

[0129] S1205: generating the PWM signal according to the inner phase shift angle and the outer phase shift angle of each port, and driving the switch tube in the bridge arm circuit by using the PWM signal.

[0130] S1206: generating the PWM signal according to the preset working mode, and driving the switch tube in the bridge arm circuit by using the PWM signal.

[0131] In order to more intuitively understand the beneficial effects brought by the technical solutions provided in the embodiments of the present application, the following will be introduced in combination with simulation diagrams.

[0132] Referring to Figure 12 , the figure is a voltage and current waveform diagram before the application of the technical solutions.

[0133] Figure 12 The voltage waveforms shown in the figure, the horizontal coordinate is time, and the vertical coordinate is voltage, in which three waveforms represent V ab , V cd , and V ef .

[0134] The horizontal coordinate of the current waveform is time, and the vertical coordinate is current, in which three waveforms represent i L1 , i L2 , and i L3 .

[0135] From the current waveform diagram, the shadow can be seen, and the size of the shadow area represents the size of the backflow power existing in the converter.

[0136] Referring to Figure 13 , the figure is a voltage and current waveform diagram after the application of the technical solutions.

[0137] The horizontal coordinate of the voltage waveform is time, and the vertical coordinate is voltage, in which three waveforms represent V ab , V cd , and V ef .

[0138] By comparing Figure 12 and Figure 13 , it can be found that after the technical solutions provided in the present application are used, Figure 13 , V ab and V ef both have a zero level.

[0139] The horizontal coordinate of the current waveform is time, and the vertical coordinate is current, in which three waveforms represent i L1 , i L2 , and i L3 .

[0140] By comparing Figure 12 and Figure 13 , it can be seen that the shadow, Figure 13The shadow area is reduced, that is, the backflow power is reduced after the technical solution provided in the application is applied, that is, the active power is improved, and the power conversion efficiency of the converter is improved.

[0141] The above description of disclosed embodiments enables one of ordinary skill in the art to make or use the application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein can be applied to other embodiments without departing from the spirit or scope of the application. Thus, the present application is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A multi-port converter, characterized in that, include: N ports, N bridge arm circuits, N-port transformers, and a controller; where N is an integer greater than or equal to 3; each bridge arm circuit includes at least two bridge arms; The N-port transformer includes N windings; each of the N windings corresponds one-to-one with one of the N bridge arm circuits; each of the N windings is connected to a corresponding bridge arm circuit. The controller is used to control the inner phase shift angle of the bridge arm circuit of the voltage mismatch port among the N ports to be zero, and to dynamically adjust the inner and outer phase shift angles of each port based on the preset electrical parameters of each port. The electrical parameters are at least one of the following: voltage, current or power. The controller is also used to convert the bridge arm input voltages of the N bridge arm circuits to the same port according to the turns ratio of the N-port transformer, and the port with the smallest converted voltage is determined as the voltage mismatch port. The inner phase shift angle is the phase angle difference between the switching transistors of the two bridge arms, and the outer phase shift angle is the phase angle difference between the switching transistors of any two bridge arms.

2. The converter according to claim 1, characterized in that, When the preset electrical parameter is voltage, the controller is specifically used to obtain the outward and inward phase angles of the remaining N-1 ports based on the midpoint voltage of the bridge arm of port i, the midpoint voltage of the bridge arm of port j, and the phase angle difference between them; j is the voltage mismatch port, and i is any one of the remaining N-1 ports.

3. The converter according to claim 2, characterized in that, The controller is specifically used to obtain the outward and inward phase angles of the remaining N-1 ports according to the following preset conditions; The preset conditions include: the voltage amplitude at the midpoint of the bridge arm of port i multiplied by cos( Ψ ij It is equal to the voltage magnitude at the midpoint of the bridge arm at port j. Ψ ij Let be the phase angle difference between the midpoint voltage of the bridge arm at port i and the midpoint voltage of the bridge arm at port j.

4. The converter according to claim 3, characterized in that, The preset conditions specifically include: the amplitude of the fundamental component of the voltage at the midpoint of the bridge arm of port i multiplied by cos( Ψ ij The amplitude of the fundamental component of the voltage at the midpoint of the bridge arm at port j is equal to the amplitude of the fundamental component of the voltage at port j. Ψ ij Let be the phase angle difference between the midpoint voltage of the bridge arm at port i and the midpoint voltage of the bridge arm at port j.

5. The converter according to any one of claims 1-4, characterized in that, The bridge arm circuit includes at least one of the following: a two-level topology or a multi-level topology.

6. The converter according to claim 5, characterized in that, N is 3, the bridge arm circuit is an H-bridge full-bridge circuit; the converter includes three ports for connecting a DC power supply, an energy storage battery and a load, respectively.

7. The converter according to claim 6, characterized in that, The DC power source is a photovoltaic array.

8. A power supply system, characterized in that, include: The multiport converter according to any one of claims 1-7.

9. A control method for a multi-port converter, characterized in that, The multi-port converter includes: N ports, N bridge arm circuits, an N-port transformer, and a controller; where N is an integer greater than or equal to 3; the N-port transformer includes N windings; the N windings and the N bridge arm circuits correspond one-to-one; each of the N windings is connected to a corresponding bridge arm circuit; The method includes: The inner phase shift angle of the bridge arm circuit of the voltage mismatch port among the N ports is controlled to be zero; The inner and outer phase shift angles of each port are dynamically adjusted based on the preset electrical parameters of each port. The preset electrical parameters are at least one of the following: voltage, current, or power. The inner phase shift angle is the phase angle difference between the switching transistors of the two bridge arms, and the outer phase shift angle is the phase angle difference between the switching transistors of any two bridge arms. The method further includes: Based on the turns ratio of the N-port transformer, the input voltages of the N bridge arm circuits are converted to the same port, and the port with the lowest converted voltage is determined as the voltage mismatch port.

10. The control method according to claim 9, characterized in that, When the preset electrical parameters are voltage, the dynamic adjustment of the inner and outer phase shift angles of each port based on the preset electrical parameters of each port specifically includes: Based on the midpoint voltage of the bridge arm at port i, the midpoint voltage of the bridge arm at port j, and the phase angle difference between them, the outward and inward phase angles of the remaining N-1 ports are obtained; j is the voltage mismatch port, and i is any one of the remaining N-1 ports.

11. The control method according to claim 10, characterized in that, The step of obtaining the outward and inward phase shift angles of the remaining N-1 ports based on the midpoint voltage of the bridge arm at port i, the midpoint voltage of the bridge arm at port j, and the phase angle difference between them specifically includes: The outer and inner phase shift angles of the remaining N-1 ports are obtained based on the following preset conditions; The preset conditions include: the voltage amplitude at the midpoint of the bridge arm of port i multiplied by cos( Ψ ij It is equal to the voltage magnitude at the midpoint of the bridge arm at port j. Ψ ij Let be the phase angle difference between the midpoint voltage of the bridge arm at port i and the midpoint voltage of the bridge arm at port j.

12. The control method according to claim 11, characterized in that, The preset conditions include: the amplitude of the fundamental component of the voltage at the midpoint of the bridge arm of port i multiplied by cos( Ψ ij The amplitude of the fundamental component of the voltage at the midpoint of the bridge arm at port j is equal to the amplitude of the fundamental component of the voltage at port j. Ψ ij Let be the phase angle difference between the midpoint voltage of the bridge arm at port i and the midpoint voltage of the bridge arm at port j.

13. The control method according to claim 9, characterized in that, Also includes: The bridge arm input voltage of the N bridge arm circuits is detected, and it is determined whether there is a voltage mismatch port based on the bridge arm input voltage of the N bridge arm circuits. If there is no mismatch port, a PWM signal is generated according to the preset working mode, and the PWM signal is used to drive the switching transistor in the bridge arm circuit.

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