Dual-active bridge type conversion circuit, converter and energy storage power supply

Abstract

The invention relates to a dual-active bridge type conversion circuit, a converter and an energy storage power supply. The dual-active bridge type conversion circuit comprises a primary side full-bridge module, a reference conversion module, at least one group of additional conversion modules and a control module, the at least one group of additional conversion modules is connected in parallel with the reference conversion module, and each group of additional conversion modules comprises a switch unit; the primary side full-bridge module, the reference conversion module, the at least one group of additional conversion modules and each switch unit are connected with the control module; the control module is used for controlling the switch unit to be in an off state under the condition that the dual-active bridge type conversion circuit is in first load or no-load operation, and performing phase shift control on power devices in the primary side full-bridge module and the reference conversion module; the first load is smaller than or equal to a preset light load threshold. By adopting the dual-active bridge type conversion circuit, the efficiency of the DAB converter can be improved.

Description

Technical Field

[0001] The present application relates to the technical field of converters, and in particular to a dual-active bridge conversion circuit, a converter and an energy storage power supply. Background Art

[0002] With the continuous development of power electronics technology, dual active bridge (DAB) converter has attracted widespread attention and application due to its reliable and flexible power transmission characteristics.

[0003] In the related art, the power devices of the DAB converter can be controlled from a software perspective by combining phase shift control and frequency modulation control to achieve a larger soft switching range and improve the efficiency of the local area.

[0004] However, in light load or no-load scenarios, the control method of the related art cannot improve the efficiency of the DAB converter. Summary of the invention

[0005] Based on this, it is necessary to provide a dual-active bridge conversion circuit, converter and energy storage power supply to improve the efficiency of the DAB converter in response to the above technical problems.

[0006] In a first aspect, the present application provides a dual-active bridge conversion circuit, which includes a primary full-bridge module, a reference conversion module, at least one group of additional conversion modules and a control module; at least one group of additional conversion modules are connected in parallel with the reference conversion module, and at least one group of additional conversion modules includes a switch unit; the primary full-bridge module, the reference conversion module, at least one group of additional conversion modules, and each switch unit are connected to the control module;

[0007] A control module is used to control the switch unit to be in an off state and to perform phase shift control on power devices in the primary full-bridge module and the reference conversion module when the dual-active bridge conversion circuit is in a first load or no-load operation; the switch unit is in an off state to cut off the connection between the reference conversion module and at least one group of additional conversion modules; the first load is less than or equal to a preset light load threshold.

[0008] In one embodiment, the reference transformation module includes a reference voltage transformation unit and a reference secondary full-bridge unit, and at least one group of additional transformation modules also includes an additional voltage transformation unit and an additional secondary full-bridge unit. The reference voltage transformation unit is connected in parallel with the additional voltage transformation unit, and the reference secondary full-bridge unit is connected in parallel with each additional secondary full-bridge unit.

[0009] In one embodiment, the reference voltage conversion unit includes a reference inductor and a reference transformer, each additional voltage conversion unit includes an additional inductor and an additional transformer, and the reference inductor is connected in parallel with each additional inductor, and the reference transformer is connected in parallel with each additional transformer.

[0010] In one embodiment, each group of additional conversion modules includes a switch unit, the switch unit includes a first switch and a second switch, the first switch is arranged between the reference inductor and the additional inductor, and the second switch is arranged between the reference secondary full-bridge unit and the additional secondary full-bridge unit;

[0011] The control module is used to control the first switch and the second switch to be in an off state when the dual-active bridge conversion circuit is in a first load or no-load operation.

[0012] In one of the embodiments, the control module is also used to control the switch unit to be in the on state when the dual-active bridge conversion circuit is in the second load operation, and to perform phase shift control on the power devices in the primary full-bridge module, the reference conversion module, and at least one group of additional conversion modules; the switch unit is used to conduct the connection between the reference conversion module and at least one group of additional conversion modules; the second load is greater than the preset light load threshold.

[0013] In one of the embodiments, the dual active bridge converter circuit further includes a primary power supply and a secondary power supply;

[0014] The primary power supply is connected to the primary full-bridge module, and the secondary power supply is connected to the reference conversion module.

[0015] In one of the embodiments, the control module is also used to perform phase shift control on the power devices in the primary full-bridge module and the reference conversion module according to the primary voltage of the primary power supply and the output current of the reference conversion module when the dual-active bridge conversion circuit is in the first load or no-load operation.

[0016] In one embodiment, the control module is further used to determine the triple phase shift value of the power device according to the primary voltage of the primary power supply and the output current of the reference conversion module; and based on the triple phase shift value, perform phase shift control on the power devices in the primary full-bridge module and the reference conversion module;

[0017] The triple phase shift value of the power device is determined based on the voltage transfer ratio and output power of the dual active bridge conversion circuit.

[0018] In a second aspect, the present application further provides a converter, which includes the content of any one embodiment of the dual active bridge conversion circuit in the first aspect.

[0019] In a third aspect, the present application further provides an energy storage power supply, which includes the content of the converter in the second aspect.

[0020] The above-mentioned dual-active bridge conversion circuit, converter and energy storage power supply, the dual-active bridge conversion circuit includes a primary full-bridge module, a reference conversion module, at least one group of additional conversion modules and a control module; at least one group of additional conversion modules are connected in parallel with the reference conversion module, and at least one group of additional conversion modules includes a switch unit; the primary full-bridge module, the reference conversion module, at least one group of additional conversion modules, and each switch unit are connected to the control module; the control module is used to control the switch unit to be in a disconnected state when the dual-active bridge conversion circuit is in a first load or no-load operation, and to perform phase shift control on the power devices in the primary full-bridge module and the reference conversion module; the switch unit is in a disconnected state to cut off the connection between the reference conversion module and at least one group of additional conversion modules; the first load is less than or equal to a preset light load threshold. On the basis of the circuit composed of the primary full-bridge module and the reference conversion module, at least one group of additional conversion circuits is added, and the connection mode between each group of additional conversion circuits and the reference conversion circuit is limited, that is, they are connected in parallel, and a switch module is set on at least one group of additional conversion circuits. In the light load or no-load state, the control module increases the inductor power by controlling the disconnection of the switch module, thereby increasing the current left by the inductor. In addition, the phase shift of each power device is controlled. By controlling the two angles of the switch module and the phase shift, the soft switching range can be expanded, thereby effectively improving the working efficiency of the dual-active bridge conversion circuit. At the same time, in the no-load or light load condition, since at least one group of additional conversion modules does not work, the power consumption of the dual-active bridge conversion circuit is reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present application or related technologies, the drawings required for use in the embodiments of the present application or related technical descriptions will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0022] Figure 1 is a circuit diagram of a DAB converter in one embodiment;

[0023] Figure 2 is a schematic diagram of a DAB converter in a soft switching process according to an embodiment;

[0024] Figure 3 is a schematic diagram of a soft switching range of a DAB converter in one embodiment;

[0025] Figure 4 is a circuit diagram of a dual active bridge conversion circuit in one embodiment;

[0026] Figure 5 is a circuit diagram of a dual active bridge conversion circuit in one embodiment;

[0027] Figure 6 FIG. 4 is a schematic diagram of phase shift control in an embodiment.

[0028] Description of reference numerals:

[0029] 10: Dual active bridge conversion circuit;

[0030] 11: Primary side full bridge module;

[0031] 12: reference transformation module;

[0032] 121: reference voltage conversion unit;

[0033] 122: Reference to the secondary full-bridge unit;

[0034] 13: Additional transformation module;

[0035] 131: switch unit;

[0036] 132: additional voltage conversion unit;

[0037] 133: Additional secondary full-bridge unit;

[0038] 14: Control module. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0040] In the description of the present application, the terms "first" and "second" are used for descriptive purposes only and are not to be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of the present application, "plurality" means at least two, for example, two, three, etc., unless otherwise clearly and specifically defined.

[0041] In this application, unless otherwise clearly defined and specified, the terms "connected" and "connection" should be understood in a broad sense, for example, it can be an electrical connection, a direct connection, or an indirect connection through an intermediate medium, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0042] Before introducing the technical solution of the present application in detail, a brief description of the background technology of the present application is first given.

[0043] In actual use of the DAB converter, if the primary voltage is high and the secondary voltage is low, the secondary current will be large, which will cause the temperature inside the DAB converter to rise. Therefore, based on the heat dissipation considerations of the DAB converter, the transformer and the secondary switch tube are usually divided into two groups of unit circuits. Figure 1 The circuit diagram of the DAB converter is shown in FIG. 1 . As can be seen from the figure, the primary side is connected in series and the secondary side is connected in parallel. The output voltage of the primary power supply is represented by V1, and the output voltage of the secondary power supply is represented by V2.

[0044] The efficiency of the DAB converter is related to both hardware parameters and software control. In the related art, the efficiency of the DAB converter can be improved by software control or hardware parameter adjustment.

[0045] For software control, multiple phase shift control and frequency modulation control such as one or two inner phase shifts and outer phase shifts can be used to increase the control freedom and achieve a larger zero voltage switching (ZVS) range to improve the efficiency of the local area of ​​the DAB converter.

[0046] As for hardware parameters, a larger inductance value can be designed or a power device with a smaller output capacitance can be selected according to the circuit topology characteristics of the DAB converter to increase the ZVS range and improve the efficiency of the local area of ​​the DAB converter.

[0047] Figure 2 The schematic diagram of the DAB converter in the soft switching process is shown in the figure, taking the S1S3 bridge arm in the primary full bridge as an example, including the schematic diagrams of the switch tube S1 and the switch tube S3 at time t0, time t1, time t2, and time t3. Specifically, for time t0, the switch tube S1 is in the off state, the switch tube S3 is in the on state, and the current of the inductor flows to the left and flows through the switch tube S3 channel in the positive direction. At this time, the junction capacitor connected in parallel with the switch tube S1 bears the bus voltage V1, and there is no charge in the junction capacitor connected in parallel with the switch tube S3, and the voltage at both ends is zero. For time t1, the switch tube S3 is in the off state, and the current direction of the inductor is still to the left. Since it is in the dead time of the bridge arm at this time, the switch tube S1 and the switch tube S3 are both in the off state, so the current flows through the junction capacitor connected in parallel with the switch tube S1 and the junction capacitor connected in parallel with the switch tube S3, the junction capacitor connected in parallel with the switch tube S1 is discharged, and the junction capacitor connected in parallel with the switch tube S3 is charged.

[0048] At time t2, since the junction capacitance in parallel with the switch tube S1 is the same as the junction capacitance in parallel with the switch tube S3, the junction capacitance in parallel with the switch tube S1 is discharged, the voltage is zero, the body diode is turned on, and the current continues to flow through the body diode of the switch tube S1. The junction capacitance in parallel with the switch tube S3 is charged, the voltage is V1, and the current no longer flows through the switch tube S3.

[0049] At t3, the dead time ends and the switch S1 is in the on state. Since the current previously flows through the body diode of the switch S1, the voltage is zero. Zero voltage switching is achieved at the turn-on moment, and there is almost no turn-on loss.

[0050] In summary, if ZVS is to be achieved, the necessary condition is that during the time period when switch tube S3 is turned off and switch tube S1 is turned on, the current needs to flow into the midpoint of the bridge arm to realize the charging and discharging process of switch tubes S1 and S3. Similarly, when switch tube S1 is turned off and switch tube S3 is turned on, the current needs to flow out from the midpoint of the bridge arm. In other words, to achieve ZVS, the inductance of the inductor needs to be large, or the current of the inductor needs to reach a certain value so that the inductor has enough energy to provide the switch tube with complete the charging and discharging process of the junction capacitance.

[0051] Figure 3 A schematic diagram showing the soft switching range of a DAB converter, where the abscissa represents the voltage transfer ratio of input voltage to output voltage, and the ordinate represents output power. The multiple lines in the figure represent the soft switching range at different inductance values. It can be seen that the smaller the inductance value, the smaller the soft switching range, and the larger the inductance value, the larger the soft switching range.

[0052] However, in light load or no-load scenarios, the control method of the related art cannot improve the efficiency of the DAB converter.

[0053] In view of the above problems, the present application provides a dual-active bridge conversion circuit, a converter and an energy storage power supply, which can increase multiple sets of parallel conversion units and switches from a hardware perspective, and improve the efficiency of the DAB converter in light load or no-load scenarios by controlling the switches and various power devices. Of course, the technical solutions provided in the embodiments of the present application are not limited to solving the above problems, and there are other technical effects, which can be specifically referred to in the following embodiment description. The technical solution of the present application is described in detail below.

[0054] In one embodiment, Figure 4As shown, a dual-active bridge conversion circuit 10 is provided, and the dual-active bridge conversion circuit 10 includes a primary full-bridge module 11, a reference conversion module 12, at least one group of additional conversion modules 13 and a control module 14; at least one group of additional conversion modules 13 are connected in parallel with the reference conversion module 12, and at least one group of additional conversion modules 13 includes a switch unit 131; the primary full-bridge module 11, the reference conversion module 12, at least one group of additional conversion modules 13, and each switch unit 131 are connected to the control module 14;

[0055] The control module 14 is used to control the switch unit 131 to be in an off state and to perform phase shift control on the power devices in the primary full-bridge module 11 and the reference conversion module 12 when the dual-active bridge conversion circuit 10 is in a first load or no-load operation; the switch unit 131 is in an off state to cut off the connection between the reference conversion module 12 and at least one group of additional conversion modules 13; the first load is less than or equal to a preset light load threshold.

[0056] In the embodiment of the present application, at least one group of additional conversion modules 13 can be added on the basis of the traditional dual-active bridge conversion circuit 10, that is, the dual-active bridge conversion circuit 10 includes a primary full-bridge module 11, a reference conversion module 12 and at least one group of additional conversion modules 13. It should be noted here that, whether it is the reference conversion module 12 or any group of additional conversion modules 13, they all include an inductor, a converter and a secondary full-bridge unit.

[0057] On this basis, each group of additional transformation modules 13 is connected in parallel with the reference transformation module 12, and each group of additional transformation modules 13 is also connected in parallel. It should be noted here that parallel connection means that each unit in the reference transformation module 12 is connected in parallel with each unit in each group of additional transformation modules 13. For example, the inductor in the reference transformation module 12 is connected in parallel with the inductor in each group of additional transformation modules 13, or the converter in the reference transformation module 12 is connected in parallel with the converter in each group of additional transformation modules 13, or the secondary full-bridge unit in the reference transformation module 12 is connected in parallel with the secondary full-bridge unit in each group of additional transformation modules 13.

[0058] The switch unit 131 in at least one group of additional conversion units may be a main switch unit 131, or each group of additional conversion units may include a switch unit 131, or at least one group of additional conversion units may include a main switch unit 131 and a plurality of branch switch units 131. The switch unit 131 may be a relay, a push button switch, a knob switch, a metal oxide semiconductor field effect transistor (MOS tube) or a triode, etc.

[0059] When the dual active bridge conversion circuit 10 is in a light load (a first load less than or equal to a preset light load threshold) or no-load state, the control module 14 controls the switch unit 131 to disconnect, and at this time, the reference conversion module 12 is disconnected from all the additional conversion modules 13. That is, the primary full bridge module 11 and the reference conversion module 12 in the DAB conversion circuit work normally, and all the additional conversion modules 13 do not work. At the same time, the control module 14 can also control the power devices in the primary full bridge module 11 and the reference conversion module 12 to perform phase shift control, so as to achieve the highest efficiency of the DAB conversion circuit under light load or no-load conditions.

[0060] When the dual active bridge conversion circuit 10 is in a normal load (greater than a preset light load threshold) or heavy load state, the control module 14 controls the switch unit 131 to be turned on, and at this time, the reference conversion module 12 is connected to all the additional conversion modules 13. That is, the primary full bridge module 11, the reference conversion module 12 and at least one group of additional conversion modules 13 in the DAB conversion circuit all work normally. At the same time, the control module 14 can also control the power devices in the primary full bridge module 11, the reference conversion module 12 and at least one group of additional conversion modules 13 to perform phase shift control, so as to achieve the highest efficiency of the DAB conversion circuit under normal load conditions.

[0061] Among them, the control module 14 can be but is not limited to a pulse width modulation (PWM) control chip, a control integrated circuit (IC), a voltage reference source, a phase locked loop (PLL) control chip, a current detection chip, a metal-oxide-semiconductor field-effect transistor (MOSFET) driver chip, etc.

[0062] The above-mentioned dual-active bridge conversion circuit 10 includes a primary full-bridge module 11, a reference conversion module 12, at least one group of additional conversion modules 13 and a control module 14; at least one group of additional conversion modules 13 are connected in parallel with the reference conversion module 12, and at least one group of additional conversion modules 13 includes a switch unit 131; the primary full-bridge module 11, the reference conversion module 12, at least one group of additional conversion modules 13, and each switch unit 131 are connected to the control module 14; the control module 14 is used to control the switch unit 131 to be in an off state when the dual-active bridge conversion circuit 10 is in a first load or no-load operation, and to perform phase shift control on the power devices in the primary full-bridge module 11 and the reference conversion module 12; the switch unit 131 is in an off state to cut off the connection between the reference conversion module 12 and at least one group of additional conversion modules 13; the first load is less than or equal to a preset light load threshold. On the basis of the circuit composed of the primary full-bridge module 11 and the reference conversion module 12, at least one group of additional conversion circuits is added, and the connection mode between each group of additional conversion circuits and the reference conversion circuit is limited, that is, they are connected in parallel, and a switch module is set on at least one group of additional conversion circuits. In the light load or no-load state, the control module 14 increases the inductance charge by controlling the disconnection of the switch module, thereby increasing the current left by the inductor. In addition, the phase shift of each power device is also controlled. By controlling the two angles of the switch module and the phase shift, the soft switching range can be expanded, thereby effectively improving the working efficiency of the dual active bridge conversion circuit 10. At the same time, in the no-load or light load condition, since at least one group of additional conversion modules 13 does not work, the power consumption of the dual active bridge conversion circuit 10 is reduced.

[0063] Next, the specific contents of the reference transformation module 12 and at least one group of additional transformation modules 13 in the above embodiment are described through an embodiment. Figure 5 As shown, the reference transformation module 12 includes a reference voltage transformation unit 121 and a reference secondary full-bridge unit 122, and at least one group of additional transformation modules 13 also includes an additional voltage transformation unit 132 and an additional secondary full-bridge unit 133. The reference voltage transformation unit 121 is connected in parallel with the additional voltage transformation unit 132, and the reference secondary full-bridge unit 122 is connected in parallel with each additional secondary full-bridge unit 133.

[0064] Figure 5The number of additional transformation modules 13 is taken as an example for explanation. It can be seen from the figure that the reference transformation module 12 and the additional transformation module 13 are connected in parallel with each other, specifically, each unit in the reference transformation module 12 and each unit in the additional transformation module 13 are connected in parallel, that is, the reference voltage transformation unit 121 in the reference transformation module 12 is connected in parallel with the additional voltage transformation unit 132 in the additional transformation module 13, and the reference secondary full-bridge unit 122 in the reference transformation module 12 is connected in parallel with the additional secondary full-bridge unit 133 in the additional transformation unit.

[0065] In one embodiment, the reference voltage conversion unit 121 includes a reference inductor L1 and a reference transformer T1, each additional voltage conversion unit 132 includes an additional inductor L2 and an additional transformer T2, and the reference inductor L1 is connected in parallel with each additional inductor L2, and the reference transformer T1 is connected in parallel with each additional transformer T2. Each group of additional conversion modules 13 includes a switch unit 131, and the switch unit 131 includes a first switch and a second switch, the first switch is arranged between the reference inductor L1 and the additional inductor L2, and the second switch is arranged between the reference secondary full-bridge unit 122 and the additional secondary full-bridge unit 133;

[0066] The control module 14 is used to control the first switch and the second switch to be in an off state when the dual-active bridge conversion circuit 10 is in a first load or no-load operation.

[0067] Continue to refer Figure 5 The primary full-bridge module 11 includes switch tubes S1-S4. The first end of the reference inductor L1 in the reference transformation module 12 is connected to the common end of the switch tubes S1 and S3. The second end of the reference inductor L1 is connected to the first end of the primary side of the reference transformer T1. The second end of the primary side of the reference transformer T1 is connected to the common end of the switch tubes S2 and S4. The first end of the first switch SW1 in the additional transformation module is connected to the common end of the switch tubes S1 and S3. The second end of the first switch SW1 is connected to the first end of the additional inductor L2. The second end of the additional inductor L2 is connected to the first end of the primary side of the additional transformer T2. The second end of the primary side of the additional transformer T2 is connected to the common end of the switch tubes S2 and S4. In other words, the first switch SW1 is set between the reference inductor L1 and the additional inductor L2, that is, the reference inductor L1 is connected in parallel with the additional inductor L2.

[0068] The reference secondary full-bridge unit 122 in the reference conversion module 12 includes switch tubes Q1-Q4, and the additional secondary full-bridge unit 133 in the additional conversion module 13 includes switch tubes Q5-Q8. The first end of the secondary side of the reference transformer T1 is connected to the common end of the switch tubes Q1 and Q3, and the second end of the secondary side of the reference transformer T1 is connected to the common end of the switch tubes Q2 and Q4. The first end of the secondary side of the additional converter T2 is connected to the common end of the switch tubes Q5 and Q7, the second end of the secondary side of the additional converter T2 is connected to the first end of the second switch SW2, and the second end of the second switch SW2 is connected to the common end of the switch tubes Q6 and Q8. It should be noted that the positive output end of the reference secondary full-bridge unit 122 is connected to the positive output end of the additional secondary full-bridge unit 133, and the negative output end of the additional secondary full-bridge unit 133 is connected to the negative output end of the reference secondary full-bridge unit 122, that is, the reference secondary full-bridge unit 122 and the additional secondary full-bridge unit 133 are connected in parallel.

[0069] From the above analysis process, it can be seen that the primary side and the secondary side in the dual active bridge conversion circuit 10 are both connected in parallel.

[0070] The reference conversion module 12 includes a reference voltage conversion unit 121 and a reference secondary full-bridge unit 122. At least one group of additional conversion modules 13 also includes an additional voltage conversion unit 132 and an additional secondary full-bridge unit 133. The reference voltage conversion unit 121 is connected in parallel with the additional voltage conversion unit 132, and the reference secondary full-bridge unit 122 is connected in parallel with each additional secondary full-bridge unit 133. The reference voltage conversion unit 121 includes a reference inductor L1 and a reference transformer T1, and each additional voltage conversion unit 132 includes an additional inductor L2 and an additional transformer T2. The reference inductor L1 is connected in parallel with each additional inductor L2, and the reference transformer T1 is connected in parallel with each additional transformer T2. Each group of additional conversion modules 13 includes a switch unit 131, and the switch unit 131 includes a first switch and a second switch, wherein the first switch is arranged between the reference inductor L1 and the additional inductor L2, and the second switch is arranged between the reference secondary full-bridge unit 122 and the additional secondary full-bridge unit 133; the control module 14 is used to control the first switch and the second switch to be in an off state when the dual-active bridge conversion circuit 10 is in the first load or no-load operation. The first switch is arranged between the reference inductor L1 and the additional inductor L2, and the second switch is arranged between the reference secondary full-bridge unit 122 and the additional secondary full-bridge unit 133. Through the arrangement of the two switches, it is possible to accurately control whether at least one group of additional conversion modules 13 is working based on the operation status of the dual-active bridge conversion circuit 10, so as to ensure the working efficiency of the dual-active bridge conversion circuit 10.

[0071] Assuming that the dual-active bridge conversion circuit 10 is in normal load or heavy load, at least one group of additional conversion modules 13 works normally to ensure the normal operation of the dual-active bridge conversion circuit 10. In one embodiment, the control module 14 is also used to control the switch unit 131 to be in a conducting state when the dual-active bridge conversion circuit 10 is in a second load operation, and to perform phase shift control on the power devices in the primary full-bridge module 11, the reference conversion module 12, and at least one group of additional conversion modules 13; the switch unit 131 is used to conduct the connection between the reference conversion module 12 and at least one group of additional conversion modules 13; the second load is greater than the preset light load threshold.

[0072] In the embodiment of the present application, when the dual-active bridge conversion circuit 10 is in normal load or heavy load operation, the control module 14 can control the switch modules of some of the additional conversion modules 13 in each additional conversion module 13 to be in the on state, that is, all switches in the switch modules of some of the additional conversion modules 13 are in the on state. Alternatively, the switch modules of all the additional conversion modules 13 can also be controlled to be in the on state, so that the primary full-bridge module 11, the reference conversion module 12 and at least one group of additional conversion modules 13 in the dual-active bridge conversion circuit 10 are all working.

[0073] Continue to refer Figure 5 If the number of the additional conversion module 13 is one, the control module 14 controls the first switch SW1 and the second switch SW2 to be in the on state, and the reference inductor L1 and the additional inductor L2 work in parallel.

[0074] The control module 14 is also used to control the switch unit 131 to be in the on state when the dual-active bridge conversion circuit 10 is in the second load operation, and to perform phase shift control on the power devices in the primary full-bridge module 11, the reference conversion module 12, and at least one group of additional conversion modules 13; the switch unit 131 is used to conduct the connection between the reference conversion module 12 and at least one group of additional conversion modules 13; the second load is greater than the preset light load threshold. When the dual-active bridge conversion circuit 10 is in normal load or heavy load operation, the switch module is controlled to be turned on so that at least one group of additional conversion modules 13 works to ensure the normal operation of the dual-active bridge conversion circuit 10.

[0075] In one embodiment, the dual active bridge conversion circuit 10 further includes a primary power supply and a secondary power supply; the primary power supply is connected to the primary full bridge module 11 , and the secondary power supply is connected to the reference conversion module 12 .

[0076] Among them, the primary voltage corresponding to the primary power supply is V1, and the secondary voltage corresponding to the secondary power supply is V2.

[0077] In the embodiment of the present application, whether it is a light load or no-load situation, or a normal load or heavy load situation, the control module 14 can improve the working efficiency of the dual-active bridge conversion circuit 10 through two angles of switch control and phase shift control of power devices. The above embodiments are all descriptions of switch control, and the following describes in detail the phase shift control process of power devices under different load conditions.

[0078] Figure 6 A schematic diagram of phase shift control is shown, in which an additional conversion module 13 is still used as an example for explanation. After the control module 14 obtains the sampled voltage V1sam of the primary power supply, based on the comparison result of the sampled voltage V1sam and the reference voltage V1ref, it controls whether the additional conversion module 13 is connected to the dual active bridge conversion circuit 10. That is, when the load is light or controlled, the additional conversion module 13 is controlled not to be connected to the dual active bridge conversion circuit 10; when the load is normal or heavy, the additional conversion module 13 is controlled to be connected to the dual active bridge conversion circuit 10.

[0079] If not connected, obtain the output current I21sam of the reference conversion module 12, calculate the output power and ratio of the dual active bridge conversion circuit 10, determine the triple phase shift values ​​D1, D2 and D3, and then output a control signal based on the triple phase shift values ​​D1, D2 and D3 to perform phase shift control on the power devices in the primary full bridge module 11 and the reference conversion module 12.

[0080] In one embodiment, the control module 14 is also used to perform phase shift control on the power devices in the primary full-bridge module 11 and the reference transformation module 12 according to the primary voltage V1 of the primary power supply and the output current of the reference transformation module 12 when the dual active bridge conversion circuit 10 is in the first load or no-load operation.

[0081] Specifically, the control module 14 is also used to determine the triple phase shift value of the power device according to the primary voltage V1 of the primary power supply and the output current of the reference transformation module 12; and based on the triple phase shift value, perform phase shift control on the power devices in the primary full-bridge module 11 and the reference transformation module 12; wherein the triple phase shift value of the power device is determined based on the voltage transfer ratio and output power of the dual active bridge conversion circuit 10.

[0082] If connected, the output current I22sam of the additional conversion module 13 is obtained, and the output power and ratio of the dual active bridge conversion circuit 10 are calculated to determine the triple phase shift values ​​D1, D2 and D3, and then based on the triple phase shift values ​​D1, D2 and D3, a control signal is output to perform phase shift control on the power devices in the primary full bridge module 11 and the reference conversion module 12.

[0083] In one embodiment, the control module 14 is also used to perform phase shift control on the power devices in the primary full-bridge module 11, the reference conversion module 12 and at least one group of additional conversion modules 13 according to the primary voltage V1 of the primary power supply, the output current of the reference conversion module 12 and the output current of at least one group of additional conversion modules 13 when the dual active bridge conversion circuit 10 is in the second load operation.

[0084] Next, the specific content of the phase shift control is explained. The triple phase shift value includes three control quantities, namely, the inner phase shift angle D1 of the two bridge arms S1 and S3, S2 and S4 in the primary full-bridge module 11 in the dual-active bridge conversion circuit 10, the outer phase shift angle D2 of the primary and secondary bridge arms, and the inner phase shift angle D3 of the two bridge arms Q1 and Q3, Q2 and Q4 in the secondary full-bridge. The triple phase shift control is performed based on the inner phase shift angle D1, the outer phase shift angle D2 and the inner phase shift angle D3.

[0085] When k>1, 0≤p≤ In the case of, the internal phase shift angle D1 and the internal phase shift angle D3 can be expressed as:

[0086]

[0087] The external phase angle D2 can be expressed as:

[0088]

[0089] When k>1, When ≤p≤1, the internal phase shift angle D1 can be expressed as:

[0090]

[0091] The external phase shift angle D2 and the internal phase shift angle D3 can be expressed as:

[0092]

[0093] When k≤1, 0≤p< In the case of, the internal phase shift angle D1 can be expressed as:

[0094]

[0095] The external phase shift angle D2 is zero, and the internal phase shift angle D3 can be expressed as:

[0096]

[0097] When k≤1, When ≤p<1, the inner phase shift angle D1 is zero, and the outer phase shift angle D2 can be expressed as:

[0098]

[0099] The internal phase shift angle D3 can be expressed as:

[0100]

[0101] Wherein, p represents the output power of the dual-active bridge conversion circuit 10 ; k represents the voltage transfer ratio of the dual-active bridge conversion circuit 10 .

[0102] Furthermore, different combinations of primary and secondary voltages are formed through control strategies composed of different inner phase shift angles D1, outer phase shift angles D2 and inner phase shift angles D3.

[0103] In the above dual-active bridge conversion circuit 10, the control module 14 is also used to perform phase shift control on the power devices in the primary full-bridge module 11 and the reference conversion module 12 according to the primary voltage V1 of the primary power supply and the output current of the reference conversion module 12 when the dual-active bridge conversion circuit 10 is in the first load or no-load operation. Specifically, the control module 14 is also used to determine the triple phase shift value of the power device according to the primary voltage V1 of the primary power supply and the output current of the reference conversion module 12; and based on the triple phase shift value, perform phase shift control on the power devices in the primary full-bridge module 11 and the reference conversion module 12; wherein the triple phase shift value of the power device is determined based on the voltage transfer ratio and output power of the dual-active bridge conversion circuit 10. And, when the dual-active bridge conversion circuit 10 is in the second load operation, the power devices in the primary full-bridge module 11, the reference conversion module 12 and the at least one group of additional conversion modules 13 are phase-shifted and controlled according to the primary voltage V1 of the primary power supply, the output current of the reference conversion module 12 and the output current of the at least one group of additional conversion modules 13. Under different load conditions, the control module 14 can control the on and off of the switch unit 131, determine whether the at least one group of additional conversion modules 13 is working, and improve the working efficiency of the dual-active bridge conversion circuit 10 under different loads through the triple phase-shift control process.

[0104] In one embodiment, a converter is also provided, which includes a dual active bridge converter circuit 10. The converter can be used in various types of equipment. In one case, the converter can be set in an energy storage power supply.

[0105] The above content is a further detailed description of the embodiments of the present application in combination with specific / preferred implementation methods, and it cannot be determined that the specific implementation of the embodiments of the present application is limited to these descriptions. For ordinary technicians in the technical field to which the embodiments of the present application belong, without departing from the concept of the embodiments of the present application, it can also make several substitutions or modifications to these described implementation methods, and these substitutions or modifications should be regarded as belonging to the protection scope of the embodiments of the present application. In the description of this specification, the description of the reference terms "an embodiment", "some embodiments", "preferred embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in combination with the embodiment or example are included in at least one embodiment or example of the embodiments of the present application. In this specification, the schematic representation of the above terms does not necessarily target the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. The technical features of the above embodiments can be combined arbitrarily. In order to make the description concise, all possible combinations of the various technical features in the above embodiments are not described. However, as long as there is no contradiction in the combination of these technical features, they should be considered as the scope recorded in this specification.

[0106] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this application.

[0107] The above embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

[0108] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them; although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application, and they should all be included in the scope of the claims and specification of the present application. In particular, as long as there is no structural conflict, the various technical features mentioned in the various embodiments can be combined in any way. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

Claims

1. A dual active bridge conversion circuit, characterized in that: The dual-active bridge conversion circuit includes a primary full-bridge module, a reference conversion module, at least one group of additional conversion modules and a control module; the at least one group of additional conversion modules are connected in parallel with the reference conversion module, and the at least one group of additional conversion modules includes a switch unit; the primary full-bridge module, the reference conversion module, the at least one group of additional conversion modules, and each of the switch units are connected to the control module; The control module is used to control the switch unit to be in an off state and to perform phase shift control on the power devices in the primary full-bridge module and the reference conversion module when the dual-active bridge conversion circuit is in a first load or no-load operation; the switch unit is in an off state to cut off the connection between the reference conversion module and the at least one group of additional conversion modules; the first load is less than or equal to a preset light load threshold.

2. The circuit according to claim 1, characterized in that The reference transformation module includes a reference voltage transformation unit and a reference secondary full-bridge unit, and the at least one group of additional transformation modules also includes an additional voltage transformation unit and an additional secondary full-bridge unit. The reference voltage transformation unit is connected in parallel with the additional voltage transformation unit, and the reference secondary full-bridge unit is connected in parallel with each of the additional secondary full-bridge units.

3. The circuit according to claim 2, characterized in that The reference voltage conversion unit includes a reference inductor and a reference transformer, each additional voltage conversion unit includes an additional inductor and an additional transformer, and the reference inductor is connected in parallel with each additional inductor, and the reference transformer is connected in parallel with each additional transformer.

4. The circuit according to claim 3, characterized in that Each group of additional conversion modules includes a switch unit, the switch unit includes a first switch and a second switch, the first switch is arranged between the reference inductor and the additional inductor, and the second switch is arranged between the reference secondary full-bridge unit and the additional secondary full-bridge unit; The control module is used to control the first switch and the second switch to be in an off state when the dual-active bridge conversion circuit is in a first load or no-load operation.

5. The circuit according to any one of claims 1 to 4, characterized in that: The control module is also used to control the switch unit to be in the on state and to perform phase shift control on the power devices in the primary full-bridge module, the reference conversion module, and the at least one group of additional conversion modules when the dual-active bridge conversion circuit is operating at the second load; the switch unit is used to conduct the connection between the reference conversion module and the at least one group of additional conversion modules; the second load is greater than a preset light load threshold.

6. The circuit according to any one of claims 1 to 4, characterized in that: The dual active bridge conversion circuit also includes a primary power supply and a secondary power supply; The primary power supply is connected to the primary full-bridge module, and the secondary power supply is connected to the reference conversion module.

7. The circuit according to claim 6, characterized in that The control module is also used to perform phase shift control on the power devices in the primary full-bridge module and the reference conversion module according to the primary voltage of the primary power supply and the output current of the reference conversion module when the dual-active bridge conversion circuit is in the first load or no-load operation.

8. The circuit according to claim 7, characterized in that The control module is further used to determine the triple phase shift value of the power device according to the primary voltage of the primary power supply and the output current of the reference conversion module; and based on the triple phase shift value, perform phase shift control on the power devices in the primary full-bridge module and the reference conversion module; Wherein, the triple phase shift value of the power device is determined based on the voltage transfer ratio and output power of the dual active bridge conversion circuit.

9. A converter, characterized in that: The converter comprises the dual active bridge converter circuit as described in any one of claims 1-8.

10. An energy storage power supply, characterized in that: The energy storage power supply comprises the converter described in claim 9.

Images