Multi-port converter based on decoupling control topology and power supply system

Abstract

The invention relates to the technical field of converters, and discloses a multi-port converter based on decoupling control topology and a power supply system, and the converter comprises a dual active bridge circuit which comprises a transformer, the primary side of the transformer comprises a first bridge arm and a second bridge arm, and the first bridge arm and the second bridge arm are each provided with three switching tubes; the buck-boost circuit and the dual-active bridge circuit share the switch tubes on the first bridge arm and the second bridge arm; the control unit controls the duty ratio of the dual-active bridge circuit according to the conduction time of a target switch tube in the first bridge arm and the second bridge arm, and controls the duty ratio of the buck-boost circuit according to the simultaneous conduction time of a switch tube adjacent to the target switch tube and the target switch tube. And decoupling control is carried out on the duty ratio of the dual-active bridge circuit and the buck-boost circuit. According to the multi-port converter, power decoupling control between the ports is realized from a topological structure, and control optimization is carried out on voltage matching of the primary side and the secondary side, so that the stability of the multi-port converter is greatly improved.

Description

Technical Field

[0001] The present application relates to the technical field of converters, and in particular to a multi-port converter and a power supply system based on a decoupling control topology. Background Art

[0002] A multi-port converter (MPC) is a power electronic device that simultaneously connects multiple power supplies and loads through multiple ports. It can achieve efficient energy conversion and distribution between multiple power supplies and loads, and is widely used in power systems such as spacecraft power systems, microgrids and electric vehicles.

[0003] In the related art, a non-isolated converter is generally integrated with a bidirectional isolated converter to obtain an MPC, and the primary duty cycle control is usually used to achieve voltage and power control between the two ports of the primary side. However, due to the coupling relationship between the power control of the MPC port, when the primary input voltage fluctuates greatly, the adjustment of the primary duty cycle control will affect the load voltage of the secondary side, which will not only cause the load voltage to fluctuate greatly, but also reduce the stability of the MPC. In addition, the MPC also has the problem of voltage mismatch between the primary and secondary sides, which leads to increased losses of the MPC. Therefore, the working performance of the MPC is difficult to meet the application requirements of the power supply system. Summary of the invention

[0004] The present application provides a multi-port converter and power supply system based on a decoupling control topology, which solves the technical problem that the port control of the multi-port converter has a coupling relationship, and when the primary input voltage fluctuates, it affects the load voltage on the secondary side, resulting in poor stability of the MPC. The present application realizes power decoupling control between ports from a topological structure to improve the stability of the multi-port converter, and optimizes the control of the primary and secondary voltage matching of the multi-port converter to overcome the problem of increased reflux power caused by the mismatch between the primary and secondary voltages, thereby greatly improving the working efficiency of the multi-port converter.

[0005] In order to achieve the above objectives, the main technical solutions adopted in this application include:

[0006] In a first aspect, an embodiment of the present application provides a multi-port converter based on a decoupling control topology, the multi-port converter comprising:

[0007] a first port, a second port, and an output port;

[0008] A dual active bridge circuit, wherein the dual active bridge circuit is configured to perform bidirectional energy conversion on the first port and the output port, wherein the dual active bridge circuit comprises a transformer, the primary side of the transformer comprises a first bridge arm and a second bridge arm, and the first bridge arm and the second bridge arm each comprise three switch tubes;

[0009] a buck-boost circuit, the buck-boost circuit being configured to regulate the input voltage of the second port and send the regulated voltage to the first port, wherein the buck-boost circuit and the dual active bridge circuit share the switch tubes on the first bridge arm and the second bridge arm;

[0010] A control unit, the control unit is configured to control the on and off of the switch tubes on the first bridge arm and the second bridge arm, and control the duty cycle of the dual active bridge circuit according to the on time of the target switch tubes in the first bridge arm and the second bridge arm respectively, and control the duty cycle of the buck-boost circuit according to the simultaneous on time of an adjacent switch tube of the target switch tube and the target switch tube, so as to decouple the duty cycle of the dual active bridge circuit and the buck-boost circuit.

[0011] The multi-port converter proposed in the embodiment of the present application is provided with a topological structure in which the dual active bridge circuit and the buck-boost circuit share the switch tubes on the two bridge arms, and three switch tubes are respectively provided on the two bridge arms, and the duty cycle control of the dual active bridge circuit is realized by controlling the conduction time of the target switch tube in the switch tube, and the target switch tube and an adjacent switch tube of the target switch tube are equivalent to a switch tube in the buck-boost circuit, and then the duty cycle control of the buck-boost circuit is realized by adjusting the simultaneous conduction time of the target switch tube and the adjacent switch tube. Therefore, the embodiment of the present application controls the conduction timing between the switch tubes so that the duty cycle control of the dual active bridge circuit and the buck-boost circuit does not interfere with each other, and realizes power decoupling control while the dual active bridge circuit and the buck-boost circuit work in coordination, and then effectively avoids the influence of the duty cycle adjustment of the primary side on the load voltage of the secondary side by independently adjusting the input voltage of the two ports, so that it can adapt to power supply equipment with wide fluctuations, greatly improve the stability of the multi-port converter, and expand the scope of application of the multi-port converter.

[0012] Optionally, in some embodiments of the present application, there is a phase difference between the turn-on timing of the switch tube on the first bridge arm and the turn-on timing of the switch tube on the second bridge arm.

[0013] Optionally, in some embodiments of the present application, the first bridge arm and the second bridge arm respectively include:

[0014] A first switch tube, wherein a drain of the first switch tube is connected to a positive input terminal of the first port;

[0015] a second switch tube, wherein a drain of the second switch tube is connected to a source of the first switch tube and has a first node;

[0016] A third switch tube, wherein the drain of the third switch tube is connected to the source of the second switch tube and has a second node, the source of the third switch tube is respectively connected to the negative input ends of the first port and the second port, and the third switch tube is configured as the target switch tube.

[0017] Wherein, the control unit controls the duty cycle of the dual active bridge circuit according to the conduction time of the third switch tube, and the conduction time of the third switch tube is a preset value;

[0018] The control unit controls the duty cycle of the buck-boost circuit according to the simultaneous conduction time of the second switch tube and the third switch tube;

[0019] The control unit determines the on-time of the first switch tube according to the on-time of both the second switch tube and the third switch tube.

[0020] The embodiment of the present application controls the duty cycle of the dual active bridge circuit according to the third switch tube, and controls the duty cycle of the buck-boost circuit according to the simultaneous conduction time of the second switch tube and the third switch tube. Therefore, the embodiment of the present application can control the conduction time of the third switch tube to be fixed and only change the simultaneous conduction time of the second switch tube and the third switch tube, so that the duty cycle of the dual active bridge circuit remains unchanged, and at the same time, the duty cycle of the buck-boost circuit is adjusted, thereby effectively decoupling the power control of the dual active bridge circuit and the buck-boost circuit, and can achieve independent adjustment of the dual active bridge circuit and the buck-boost circuit when the input voltage of the first port or the second port fluctuates, thereby effectively avoiding the influence of the duty cycle adjustment on the primary side on the load voltage on the secondary side, significantly improving the stability of the multi-port converter, and enabling the multi-port converter to be applied to power supply equipment with large fluctuations, thereby expanding the scope of application.

[0021] Optionally, in some embodiments of the present application, the buck-boost circuit includes:

[0022] a first inductor, wherein a first end of the first inductor is connected to a positive input end of the second port, and a second end of the first inductor is connected to a first node on the first bridge arm;

[0023] A second inductor, wherein a first end of the second inductor is connected to the positive input end of the second port, and a second end of the second inductor is connected to a first node on the second bridge arm.

[0024] The embodiment of the present application utilizes the first inductor and the second inductor as energy storage elements in the buck-boost circuit, and charges and discharges in coordination with the on and off cycles of the switch tube to realize the boost or buck function, and the embodiment of the present application connects the second end of the first inductor and the second end of the second inductor to the first node on the bridge arm respectively, so that the second switch tube and the third switch tube on the bridge arm are equivalent to a switch tube in the buck-boost circuit, and the simultaneous conduction of the second switch tube and the third switch tube is equivalent to the conduction of a switch tube in the buck-boost circuit, so as to realize the control of the duty cycle of the buck-boost circuit according to the simultaneous conduction time of the second switch tube and the third switch tube. Therefore, no matter how the duty cycles of the second switch tube and the third switch tube change, it will not affect the duty cycle control of the buck-boost circuit, thereby realizing the decoupling of the duty cycle control of the buck-boost circuit, so that the buck-boost circuit can respond to input voltage fluctuations and make independent adjustments, effectively eliminating the influence on the load voltage.

[0025] Optionally, in some embodiments of the present application, the dual active bridge circuit further includes:

[0026] a third inductor, wherein a first end of the third inductor is connected to a second node on the first bridge arm;

[0027] A transformer, wherein the same-name end of the primary coil of the transformer is connected to the second end of the third inductor, and the opposite-name end of the primary coil of the transformer is connected to the second node on the second bridge arm.

[0028] The embodiment of the present application realizes energy transfer from the first port to the primary coil of the transformer through the third inductor, and connects the first end of the third inductor to the second node on the first bridge arm, so that the first switch tube and the second switch tube on the bridge arm are equivalent to a switch tube in the dual active bridge circuit, and the simultaneous conduction time of the first switch tube and the second switch tube is controlled to be complementary to the conduction time of the third switch tube within the switching cycle, so as to realize the control of the duty cycle of the dual active bridge circuit according to the conduction time of the third switch tube. Therefore, no matter how the simultaneous conduction time of the second switch tube and the third switch tube changes, it will not affect the duty cycle control of the dual active bridge circuit, thereby realizing the decoupling of the duty cycle control of the dual active bridge circuit, so that the dual active bridge circuit can respond to input voltage fluctuations for independent adjustment, and effectively eliminate the impact on the load voltage.

[0029] Optionally, in some embodiments of the present application, the control unit includes a first logic circuit, and the first bridge arm and the second bridge arm are respectively provided with corresponding first logic circuits, wherein the first logic circuit includes:

[0030] A first comparator, wherein a positive input terminal of the first comparator is suitable for receiving a first modulation signal, a negative input terminal of the first comparator is suitable for receiving a primary carrier signal, and an output terminal of the first comparator is suitable for outputting a third PWM signal, wherein the third PWM signal is used to control the third switch tube;

[0031] A second comparator, wherein a positive input terminal of the second comparator is adapted to receive a second modulation signal, and a negative input terminal of the second comparator is adapted to receive the primary carrier signal;

[0032] A first inverter, wherein an input end of the first inverter is connected to an output end of the second comparator, and an output end of the first inverter is suitable for outputting a second PWM signal, wherein the second PWM signal is used to control the second switch tube;

[0033] A first XOR gate, wherein a first input terminal of the first XOR gate is connected to an output terminal of the first comparator, a second input terminal of the first XOR gate is connected to an output terminal of the first inverter, and an output terminal of the first XOR gate is suitable for outputting a first PWM signal, wherein the first PWM signal is used to control the first switch tube.

[0034] In the embodiment of the present application, the first comparator compares the first modulation signal and the second modulation signal with the primary carrier signal respectively, and generates corresponding PWM signals according to the comparison results, so that the dual active bridge circuit and the buck-boost circuit are controlled to operate with the duty cycle corresponding to the first modulation signal based on the topological structure of the shared switch tube, and the buck-boost circuit is controlled to operate with the duty cycle corresponding to the second modulation signal. Therefore, the duty cycle control of the dual active bridge circuit and the buck-boost circuit is decoupled, ensuring that the voltage regulation of the first port and the second port does not interfere with each other, thereby effectively avoiding the influence of the adjustment of the primary duty cycle control on the secondary load voltage, which is beneficial to improving the stability of the multi-port transformer, and enables the multi-port converter to be applied to power supply equipment with larger fluctuations, thereby expanding the scope of application.

[0035] Optionally, in some embodiments of the present application, the first port is connected to a storage battery, and the second port is connected to a photovoltaic cell;

[0036] The control unit further includes a primary duty cycle control module, and the primary duty cycle control module includes:

[0037] A first controller, wherein the first controller is configured to perform maximum power point tracking control on the photovoltaic cell and generate a first control variable;

[0038] a second controller configured to perform constant voltage charge and discharge control on the battery and generate a second control variable;

[0039] a third controller configured to perform constant current charge and discharge control on the battery and generate a third control variable;

[0040] A modulation module is configured to determine a minimum value among the first control variable, the second control variable and the third control variable, and generate the second modulation signal according to the minimum value.

[0041] The embodiment of the present application determines the second modulation signal through the control variables generated by the first controller, the second controller and the third controller, so that the buck-boost circuit can adjust the power in response to the second modulation signal, thereby realizing the maximum power tracking (MPPT) control of the photovoltaic cell and the constant voltage or constant current charge and discharge control of the battery. Therefore, the embodiment of the present application utilizes the primary duty cycle control module to effectively improve the influence of the primary photovoltaic cell voltage fluctuation or the battery cell voltage fluctuation on the secondary load voltage, thereby ensuring the safety and stability of the multi-port converter and improving the energy supply efficiency of the photovoltaic cell and the battery.

[0042] Optionally, in some embodiments of the present application, the control unit further includes a primary-secondary side phase shift control module, and the primary-secondary side phase shift control module includes:

[0043] a fourth controller configured to generate a fourth control variable according to a difference between an output reference voltage and an output voltage sampling value of the multi-port converter;

[0044] A modulation strategy submodule, the modulation strategy submodule is configured to determine an equivalent voltage gain according to an output voltage sampling value of the multi-port converter, an input voltage sampling value of the first port, and a transformation ratio of the transformer, and to determine an operating mode of the multi-port converter according to the equivalent voltage gain, and to determine the generation of a fifth control variable and a sixth control variable according to the operating mode and the fourth control variable, wherein the fourth control variable represents an external phase shift angle between the primary and secondary sides, the fifth control variable represents an internal phase shift angle between the primary bridge arm, and the sixth control variable represents an internal phase shift angle between the secondary bridge arm;

[0045] A phase-shift controller, wherein the phase-shift controller is configured to generate the primary carrier signal and the secondary carrier signal according to the fourth control variable, the fifth control variable and the sixth control variable, wherein there is a phase difference between the primary carrier signal and the secondary carrier signal.

[0046] The embodiment of the present application realizes the voltage distribution of the primary and secondary sides through the primary-secondary phase shift control module, and uses the fourth control variable generated by the fourth controller to characterize the ratio of the phase difference corresponding to the neutral line of the full-bridge square wave on the primary side and the secondary side of the multi-port converter to 180 degrees, so that on the basis of the traditional external phase shift angle control, the fifth control variable and the sixth control variable generated by the modulation strategy submodule are used to provide two degrees of freedom of the phase shift angle inside the primary bridge arm and the phase shift angle inside the secondary bridge arm, and the primary carrier signal and the secondary carrier signal are respectively generated by the phase shift controller to achieve precise matching of the primary and secondary voltages, overcome the problem of increased reflux power due to the mismatch between the primary and secondary voltages, and optimize the zero voltage switching (Zero Voltage Switching, ZVS) performance of the multi-port converter under light load conditions, and also realize the optimization control of the inductor current stress of the multi-port converter under heavy load conditions, thereby improving the working efficiency of the multi-port converter and greatly improving the operating performance of the multi-port converter under different load conditions.

[0047] Optionally, in some embodiments of the present application, the dual active bridge circuit further includes a rectifier bridge, and the rectifier bridge is connected to the secondary coil of the transformer;

[0048] The control unit further includes a second logic circuit, wherein the second logic circuit is configured to control the switch tube of the rectifier bridge according to the secondary carrier signal and the third modulation signal;

[0049] Wherein, the second logic circuit comprises:

[0050] a third comparator, wherein a negative input terminal of the third comparator is adapted to receive the secondary carrier signal, a positive input terminal of the third comparator is adapted to receive the third modulation signal, and an output terminal of the third comparator is adapted to output a fourth PWM signal;

[0051] a second inverter, wherein an input terminal of the second inverter is connected to an output terminal of the third comparator, and an output terminal of the second inverter is suitable for outputting a fifth PWM signal;

[0052] The fourth PWM signal and the fifth PWM signal are used to control the switch tube of the rectifier bridge.

[0053] The embodiment of the present application utilizes the secondary side carrier signal generated by the primary-secondary side phase shift control module, combined with the third modulation signal to control the conduction and shutdown of the switch tube on the rectifier bridge, thereby achieving precise matching of the primary and secondary side voltages, greatly reducing the risk of increased losses due to mismatch between the primary and secondary side voltages, and optimizing the zero voltage switching (Zero Voltage Switching, ZVS) performance of the multi-port converter, and optimizing the control of the inductor current stress, thereby improving the operating performance of the multi-port converter in different scenarios.

[0054] In a second aspect, an embodiment of the present application provides a multi-port converter, comprising:

[0055] First power source;

[0056] Second power supply;

[0057] And the multi-port converter according to the above embodiment, wherein the multi-port converter comprises a first port, a second port and an output port, and the first port of the multi-port converter is connected to the first power supply, and the second port of the multi-port converter is connected to the second power supply.

[0058] The multi-port converter proposed in the embodiment of the present application utilizes the multi-port converter to perform voltage regulation on the first power supply and the second power supply, and realizes power decoupling control of the first port and the second port through the multi-port converter, so that the duty cycle control of the switch tubes on the corresponding lines of the first port and the second port do not interfere with each other, and realizes power decoupling control while the first power supply and the second power supply work in coordination, and then effectively avoids the influence of the duty cycle regulation of the switch tube on the load voltage by independently adjusting the input voltages of the two ports. Therefore, it can adapt to power supply equipment with wide fluctuations, greatly improve the stability of the multi-port converter, and expand the scope of application of the multi-port converter. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] In order to more clearly illustrate the specific implementation methods of the present application or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0060] Figure 1 A schematic diagram of the structure of a multi-port converter based on a decoupling control topology proposed in an embodiment of the present application;

[0061] Figure 2 This is a schematic diagram of an equivalent circuit of a dual active bridge circuit proposed in an embodiment of the present application;

[0062] Figure 3 This is a schematic diagram of an equivalent circuit of a buck-boost circuit proposed in an embodiment of the present application;

[0063] Figure 4 A schematic diagram of the conduction timing of the switch tube proposed in the embodiment of the present application;

[0064] Figure 5 This is a schematic diagram of the structure of the control unit proposed in the embodiment of the present application;

[0065] Figure 6 A schematic diagram of the working process of the primary-secondary side phase shift control module proposed in the embodiment of the present application;

[0066] FIG. 7( a ) is a schematic diagram of a signal waveform of a first working mode proposed in an embodiment of the present application;

[0067] FIG7( b ) is a schematic diagram of a signal waveform of a second working mode proposed in an embodiment of the present application;

[0068] FIG7( c ) is a schematic diagram of a signal waveform of a third working mode proposed in an embodiment of the present application;

[0069] FIG7( d ) is a schematic diagram of a signal waveform of a fourth working mode proposed in an embodiment of the present application;

[0070] Figure 8 This is a schematic diagram of the structure of a multi-port converter proposed in an embodiment of the present application. DETAILED DESCRIPTION

[0071] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

[0072] Multi-Port Converter (MPC) is a power electronic device that connects multiple power supplies and loads through multiple ports at the same time. It can realize efficient energy conversion and distribution between multiple power supplies and loads, and is widely used in new energy power generation fields such as spacecraft power systems, microgrids, new energy and electric vehicles. According to the different port isolation methods, the topology of MPC can be divided into non-isolated, isolated and partially isolated types. Among them, the partially isolated MPC generally integrates the non-isolated converter with the traditional full-bridge of the bidirectional isolation converter. It usually adopts the primary side duty cycle control to realize the voltage and power control of the two ports of the primary side. The partially isolated MPC can not only provide the necessary electrical isolation, but also utilize the excellent characteristics of the non-isolated port to maintain a high conversion efficiency. It has great development potential in the future spacecraft power systems, microgrids and other new energy power generation fields.

[0073] In some application scenarios, when the input voltage of a port on the primary side fluctuates greatly, the corresponding control loop of the MPC will adjust the control strategy in response to the voltage fluctuation to eliminate the impact of the input voltage fluctuation. However, in order to improve the integration of multiple ports of the MPC, some switches are usually shared between the ports. Based on this circuit topology, when the control strategy of the switch corresponding to one port is adjusted, it is bound to affect the switch control of another port, that is, the duty cycle control of the primary side is coupled, which will in turn affect the load voltage of the secondary side, not only causing large fluctuations in the load voltage, but also causing mismatches between the primary and secondary voltages, thereby reducing the stability of the MPC and seriously affecting the working performance of the MPC.

[0074] In some related technologies, the optimization of control strategies is used to solve the power control coupling problem between ports. For example, by setting the control loop bandwidth and introducing decoupling control variables, the multi-port converter, which is a multi-input-multi-output control system, is converted into multiple single-input-single-output control systems to achieve approximate decoupling between the control loops of each port. However, this decoupling method has the problem of increased losses due to the mismatch between the primary and secondary voltages. As a result, MPC will generate large current stress and reflux power, resulting in reduced transmission efficiency of the system, limiting the application of MPC in practical engineering.

[0075] In an embodiment of the present application, a multi-port converter 10 based on a decoupling control topology is provided. The multi-port converter 10 is suitable for power supply equipment in the field of new energy power generation such as a spacecraft power supply system and a microgrid that requires multi-port expansion and has high safety requirements. Figure 1 As shown, the multi-port converter 10 includes a dual active bridge circuit 100, a buck-boost circuit 200 and a control unit 300;

[0076] The dual active bridge circuit 100 is configured to perform voltage regulation on the input voltage of the first port. The dual active bridge circuit 100 includes a transformer T. The primary side of the transformer T includes a first bridge arm and a second bridge arm, and each of the first bridge arm and the second bridge arm has three switch tubes.

[0077] In the embodiment of the present application, the input voltage of the first port is adjusted on the primary side by the dual active bridge circuit 100, so that the multi-port transformer T can stably output the voltage required by the load under different load and input conditions and provide an isolated port.

[0078] The buck-boost circuit 200 is configured to regulate the input voltage of the second port, wherein the buck-boost circuit 200 and the dual active bridge circuit 100 share the switch tubes on the first bridge arm and the second bridge arm.

[0079] In an embodiment of the present application, the input voltage of the second port is boosted on the primary side by the buck-boost circuit 200, so that a stable output voltage can be maintained when the input voltage fluctuates greatly, thereby being suitable for a power supply system with wide fluctuations and providing a non-isolated port.

[0080] The control unit 300 is configured to control the on and off of the switch tube, and control the duty cycle of the dual active bridge circuit 100 according to the on time of the target switch tube in the first bridge arm and the second bridge arm respectively, and control the duty cycle of the buck-boost circuit 200 according to the simultaneous on time of an adjacent switch tube of the target switch tube and the target switch tube, so as to decouple the duty cycle of the dual active bridge circuit 100 and the buck-boost circuit 200.

[0081] The embodiment of the present application realizes the control of the conduction timing of the switch tube through the control unit 300, and when the conduction time of the target switch tube remains unchanged, the conduction time of an adjacent switch tube of the target switch tube can be used to change the simultaneous conduction time of the adjacent switch tube and the target switch tube, and the duty cycle of the buck-boost circuit 200 can be adjusted without affecting the duty cycle of the dual active bridge circuit 100, thereby realizing the duty cycle decoupling control of the dual active bridge circuit 100 and the buck-boost circuit 200.

[0082] In addition, if Figure 1 As shown, the multi-port converter 10 further includes an output capacitor Co, and an output voltage Vo is provided to a load through two ends of the output capacitor Co.

[0083] Therefore, the multi-port converter 10 proposed in the embodiment of the present application is provided with a topological structure in which the dual active bridge circuit 100 and the buck-boost circuit 200 share the switch tubes on two bridge arms, and three switch tubes are respectively provided on the two bridge arms. The duty cycle control of the dual active bridge circuit 100 is achieved by controlling the conduction time of the target switch tube in the switch tube, and the target switch tube and an adjacent switch tube of the target switch tube are equivalent to a switch tube in the buck-boost circuit 200, and then the duty cycle control of the buck-boost circuit 200 is achieved by adjusting the simultaneous conduction time of the target switch tube and the adjacent switch tube. Therefore, the embodiment of the present application controls the conduction timing between the switching tubes so that the duty cycle control of the dual active bridge circuit 100 and the buck-boost circuit 200 do not interfere with each other, and realizes power decoupling control while the dual active bridge circuit 100 and the buck-boost circuit 200 work in coordination. Furthermore, by independently adjusting the input voltages of the two ports, the influence of the duty cycle adjustment on the primary side on the load voltage on the secondary side is effectively avoided. Therefore, it can adapt to power supply equipment with wide fluctuations, greatly improve the stability of the multi-port converter, and expand the scope of application of the multi-port converter.

[0084] In some embodiments of the present application, the first bridge arm and the second bridge arm respectively include a first switch tube, a second switch tube and a third switch tube;

[0085] Among them, the drain of the first switch tube is connected to the positive input terminal of the first port; the drain of the second switch tube is connected to the source of the first switch tube and has a first node; the drain of the third switch tube is connected to the source of the second switch tube and has a second node, the source of the third switch tube is respectively connected to the negative input terminals of the first port and the second port, and the third switch tube is configured as a target switch tube.

[0086] It should be noted that the first switch tube may be a switch tube S 1 And switch tube S 4 The second switch tube can be a switch tube S 2 And switch tube S 5 The third switch tube can be a switch tube S 3 And switch tube S 6 .

[0087] Specifically, Figure 1 As shown, the first bridge arm includes a switch tube S 1 , switch tube S 2 And switch tube S 3 The second bridge arm includes a switch tube S 4 , switch tube S 5 And switch tube S 6 , and the switch tube S 1 The drain of the switch tube S 4 The drain of the switch tube S 3 The source of the switch tube S6 The source of the switch tube S 1 And switch tube S 2 There is a first node E between them, and a switch tube S 2 And switch tube S 3 There is a second node A between the switch tube S 4 And switch tube S 5 There is a first node F between them, and the switch tube S 5 And switch tube S 6 There is a second Node B in between.

[0088] Furthermore, if Figure 1 As shown, the buck-boost circuit 200 includes a first inductor L 1 and the second inductor L 2 , where the first inductor L 1 The first end of the first inductor L is connected to the positive input end of the second port. 1 The second end of the second inductor L is connected to the first node E on the first bridge arm; 2 The first end of the second inductor L is connected to the positive input end of the second port. 2 The second end is connected to the first node F on the second bridge arm.

[0089] Furthermore, if Figure 1 As shown, the dual active bridge circuit 100 further includes a third inductor L k and transformer T, where the third inductor L k The first end of the transformer T is connected to the second node A on the first bridge arm, and the same end of the primary coil of the transformer T is connected to the third inductor L k The second end of the primary coil of the transformer T is connected to the second node B on the second bridge arm.

[0090] In some embodiments of the present application, the control unit 300 controls the duty cycle of the dual active bridge circuit 100 according to the conduction time of the third switch tube, and the conduction time of the third switch tube is a preset value;

[0091] The control unit 300 controls the duty cycle of the buck-boost circuit 200 according to the simultaneous conduction time of the second switch tube and the third switch tube, and adjusts the input voltage of the second port by changing the simultaneous conduction time of the second switch tube and the third switch tube;

[0092] The conduction time of the first switch tube is determined according to the simultaneous conduction time of the second switch tube and the third switch tube.

[0093] The embodiment of the present application controls the duty cycle of the dual active bridge circuit 100 according to the third switch tube, and controls the duty cycle of the buck-boost circuit 200 according to the simultaneous conduction time of the second switch tube and the third switch tube. Therefore, the embodiment of the present application can control the conduction time of the third switch tube to be fixed and only change the simultaneous conduction time of the second switch tube and the third switch tube, so that the duty cycle of the dual active bridge circuit 100 remains unchanged, and the duty cycle of the buck-boost circuit 200 is adjusted, thereby effectively decoupling the power control of the dual active bridge circuit 100 and the buck-boost circuit 200, and can achieve independent adjustment of the dual active bridge circuit 100 and the buck-boost circuit 200 when the input voltage at the first port or the second port fluctuates, thereby effectively avoiding the influence of the duty cycle adjustment on the primary side on the load voltage on the secondary side, significantly improving the stability of the multi-port converter, and enabling the multi-port converter to be applied to power supply equipment with large fluctuations, thereby expanding the scope of application.

[0094] The multi-port converter 10 in the embodiment of the present application utilizes Figure 1 The circuit topology shown, combined with the control unit 300 controlling the conduction timing of the switch tube, realizes the decoupling control of the dual active bridge circuit 100 and the buck-boost circuit 200. The principle of the decoupling control is described in detail below.

[0095] The above multi-port converter 10 can be equivalent to the dual active bridge circuit 100 as follows Figure 2 The dual active bridge circuit (Dual Active Bridge, DAB) shown in FIG. 1 and the buck-boost circuit 200 are equivalent to the following Figure 3 The interleaved bidirectional buck / boost circuit is shown.

[0096] Specifically, in the switch tube S 1 When it is turned on, it is equivalent to the equivalent switch tube S of the interleaved bidirectional buck / boost circuit. 11 When the switch tube S 2 And switch tube S 3 When both are turned on at the same time, it is equivalent to the equivalent switch tube S of the interleaved bidirectional buck / boost circuit. 12 Similarly, in the switch tube S 4 When it is turned on, it is equivalent to the equivalent switch tube S of the interleaved bidirectional buck / boost circuit. 13 When the switch tube S 5 And switch tube S 6 When it is turned on, it is equivalent to the equivalent switch tube S of the interleaved bidirectional buck / boost circuit. 14 Conductivity.

[0097] Therefore, the embodiment of the present application uses the first inductor L 1 and the second inductor L2 As an energy storage element in the buck-boost circuit 200, it is charged and discharged in coordination with the on and off cycles of the switch tube to achieve a boost or buck function. 1 The second end of the second inductor L 2 The second end of the bridge arm is connected to the first node E and F on the bridge arm, so that the switch tube S on the bridge arm is used. 2 And switch tube S 3 It is equivalent to a switch tube in the buck-boost circuit, and the switch tube S 2 And switch tube S 3 The simultaneous conduction of the switch tube S is equivalent to the conduction of a switch tube in the buck-boost circuit 200. 2 And switch tube S 3 The on-time of the switch tube S is used to control the duty cycle of the buck-boost circuit 200. 2 And switch tube S 3 No matter how their respective duty cycles change, it will not affect the duty cycle control of the buck-boost circuit, thereby achieving decoupling of the duty cycle control of the buck-boost circuit 200, allowing the buck-boost circuit 200 to independently adjust in response to input voltage fluctuations, effectively eliminating the impact on the load voltage.

[0098] In the switch tube S 1 And switch tube S 2 When it is turned on, it is equivalent to the equivalent switch tube S of the DAB circuit. 21 When the switch tube S 3 When turned on, it is equivalent to the equivalent switch tube S of the DAB circuit 22 Similarly, in the switch tube S 4 And switch tube S 5 When it is turned on, it is equivalent to the equivalent switch tube S of the DAB circuit. 23 When the switch tube S 6 When turned on, it is equivalent to the equivalent switch tube S of the DAB circuit 24 Conductivity.

[0099] Therefore, the embodiment of the present application uses the third inductor L k Realize the energy transfer from the first port to the primary coil of the transformer, and connect the third inductor L k The first end of the first bridge arm is connected to the second node A on the first bridge arm, so that the switch tube S on the bridge arm is used 1 And switch tube S 2 It is equivalent to a switch tube in the dual active bridge circuit 100 and controls the switch tube S 1 And switch tube S 2 The conduction time of the switch tube S 3 The conduction time of the switch tube S is complementary in the switching cycle. 3The on-time realizes the control of the duty cycle of the dual active bridge circuit 100. 2 And switch tube S 3 No matter how the conduction time changes, it will not affect the duty cycle control of the dual active bridge circuit, thereby achieving decoupling of the duty cycle control of the dual active bridge circuit 100, so that the dual active bridge circuit 100 can be independently adjusted in response to input voltage fluctuations, effectively eliminating the impact on the load voltage.

[0100] It should be noted that, in some embodiments of the present application, there is a phase difference between the turn-on timing of the switch tube on the first bridge arm and the turn-on timing of the switch tube on the second bridge arm, and the phase difference is the phase shift angle in the primary bridge arm. Therefore, the embodiment of the present application takes the first bridge arm as an example. Figure 4 The above switch tube S 1 To S 3 And the corresponding conduction timing of the equivalent switch tube. Among them, the first modulation signal μ ctrl1 is equal to 0.5, the second modulation signal μ ctrl2 It varies between 0 and 0.5. tril1 The comparison is performed to generate the corresponding PWM signal, which in turn controls the conduction of the corresponding switch tube.

[0101] like Figure 4 As shown, the equivalent switch tube S 22 The on-time of the switch tube S is equivalent to the duty cycle of the DAB circuit. 3 The on-time determines that the duty cycle of the dual active bridge circuit 100 is 0.5T s , where T s is the conduction period of the multi-port converter 10. 12 The on-time of the switch tube S is equivalent to the duty cycle of the interleaved bidirectional buck / boost circuit. 2 And switch tube S 3 The on-time of the buck-boost circuit 200 determines the duty cycle of DT s , where D varies between 0 and 0.5. ctrl1 Keep at 0.5 and the second modulation signal μ ctrl2 The duty cycle D of the buck-boost circuit 200 is kept between 0 and 0.5, and the buck-boost circuit 200 operates at a duty cycle D, while the dual active bridge circuit 100 always operates at a duty cycle of 0.5, that is, no matter how the duty cycle D of the buck-boost circuit 200 changes, it will not affect the duty cycle of the dual active bridge circuit 100, thereby achieving mutual decoupling of duty cycle control between the dual active bridge circuit 100 and the buck-boost circuit 200.

[0102] In some embodiments of the present application, Figure 5As shown, the control unit 300 includes a first logic circuit 310, and the first bridge arm and the second bridge arm are respectively provided with corresponding first logic circuits 310. It should be noted that the first logic circuit 310 generates a first PWM signal for controlling the first switch tube, a second PWM signal for controlling the second switch tube, and a third PWM signal for controlling the third switch tube, wherein the first PWM signal may be a PWM signal V GS1 and PWM signal V GS4 , the second PWM signal can be a PWM signal V GS2 and PWM signal V GS5 , the third PWM signal may be a PWM signal V GS3 and PWM signal V GS6 .

[0103] Further, the first logic circuit 310 corresponding to the first bridge arm includes a first comparator 311, a second comparator 312, a first inverter 313 and a first XOR gate 314;

[0104] The positive input terminal of the first comparator 311 is suitable for receiving the first modulation signal μ ctrl1 The negative input terminal of the first comparator 311 is adapted to receive the primary carrier signal μ tril1 The output terminal of the first comparator 311 is suitable for outputting a PWM signal V GS3 , where the PWM signal V GS3 Used to control the switch tube S 3 ;

[0105] The positive input terminal of the second comparator 312 is adapted to receive the second modulation signal μ ctrl2 The negative input terminal of the second comparator 312 is suitable for receiving the primary carrier signal μ tril1 ;

[0106] The input end of the first inverter 313 is connected to the output end of the second comparator 312, and the output end of the first inverter 313 is suitable for outputting a PWM signal V GS2 , where the PWM signal V GS2 Used to control the switch tube S 2 ;

[0107] The first input end of the first XOR gate 314 is connected to the output end of the first comparator 311, the second input end of the first XOR gate 314 is connected to the output end of the first inverter 313, and the output end of the first XOR gate 314 is suitable for outputting the PWM signal V GS1 , where the PWM signal V GS1 Used to control the switch tube S 1 .

[0108] Likewise, if Figure 5As shown, the first logic circuit 320 corresponding to the second bridge arm has the same topological structure as the first logic circuit 310. Specifically, the first logic circuit 320 includes a first comparator 321, a second comparator 322, a first inverter 323 and a first XOR gate 324;

[0109] The positive input terminal of the first comparator 321 is suitable for receiving the first modulation signal μ ctrl1 The negative input terminal of the first comparator 321 is suitable for receiving the primary carrier signal μ tril2 The output terminal of the first comparator 321 is suitable for outputting a PWM signal V GS6 , where the PWM signal V GS6 Used to control the switch tube S 6 ;

[0110] The positive input terminal of the second comparator 322 is adapted to receive the second modulation signal μ ctrl2 The negative input terminal of the second comparator 322 is suitable for receiving the primary carrier signal μ tril2 ;

[0111] The input end of the first inverter 323 is connected to the output end of the second comparator 322, and the output end of the first inverter 323 is suitable for outputting a PWM signal V GS5 , where the PWM signal V GS5 Used to control the switch tube S 5 ;

[0112] The first input terminal of the first XOR gate 324 is connected to the output terminal of the first comparator 321, the second input terminal of the first XOR gate 324 is connected to the output terminal of the first inverter 323, and the output terminal of the first XOR gate 324 is suitable for outputting the PWM signal V GS4 , where the PWM signal V GS4 Used to control the switch tube S 4 .

[0113] It should be noted that the primary carrier signal μ tril1 and the primary carrier signal μ tril2 There is a phase difference.

[0114] In the embodiment of the present application, the first comparator converts the first modulation signal μ ctrl1 , the second modulation signal μ ctrl2 The first modulation signal μ is used to generate a PWM signal based on the comparison result, so that the dual active bridge circuit 100 and the buck-boost circuit 200 can control the dual active bridge circuit 100 to generate a PWM signal based on the topological structure of the shared switch tube. ctrl1 The corresponding duty cycle works, and the buck-boost circuit 200 is controlled to use the second modulation signal μ ctrl2The corresponding duty cycle works, thereby realizing the decoupling of the duty cycle control of the dual active bridge circuit 100 and the buck-boost circuit 200, ensuring that the voltage regulation of the first port and the second port do not interfere with each other, thereby effectively avoiding the influence of the adjustment of the primary side duty cycle control on the secondary side load voltage, which is beneficial to improving the stability of the multi-port transformer, and enables the multi-port converter to be applied to power supply equipment with larger fluctuations, thereby expanding the scope of application.

[0115] In some embodiments of the present application, the first port is connected to a storage battery, and the second port is connected to a photovoltaic cell. Figures 1 to 4 As shown, the battery provides a battery terminal voltage V b , the photovoltaic cell provides the photovoltaic input voltage V pv .

[0116] Furthermore, in some embodiments of the present application, the control unit 300 further includes a primary duty cycle control module 330, and the primary duty cycle control module 330 includes:

[0117] The first controller 331 is configured to perform maximum power tracking control on the photovoltaic cell and generate a first control variable u IVR ;

[0118] The second controller 332 is configured to perform constant voltage charge and discharge control on the battery and generate a second control variable u BVR ;

[0119] The third controller 333 is configured to perform constant current charge and discharge control on the battery and generate a third control variable u BCR ;

[0120] The modulation module 334 is configured to determine the first control variable u IVR , the second control variable u BVR and the third control variable u BCR The minimum value in the above equation is used to generate the second modulation signal μ according to the minimum value. ctrl2 .

[0121] Among them, Figure 5 As shown, the first controller 331, the second controller 332 and the third controller 333 are all proportional integral (PI) controllers. Specifically, the working process of the primary duty cycle control module 330 includes the following steps:

[0122] Step S11, the first controller 331 receives the input voltage reference value V mppt And the sampled photovoltaic input voltage V pvThe difference is processed by the first controller 331 to obtain the first control variable u IVR The second controller 332 receives the maximum charging voltage V bmax And the sampled battery terminal voltage V b The difference is processed by the second controller 332 to obtain the second control variable u BVR The third controller 333 receives the maximum battery charging current I bmax And the sampled battery output current I b The difference is processed by the third controller 333 to obtain the third control variable u BCR .

[0123] Step S12, taking the first control variable u IVR , the second control variable u BVR and the third control variable u BCR The minimum value in is taken as the second modulation signal μ ctrl2 , and the second modulation signal μ ctrl2 The PWM signal V generated by the first logic circuit 310 and the first logic circuit 320 is sent to the first logic circuit 310 and the first logic circuit 320. GS1 To V GS6 Control switch tube S 1 To S 6 , in order to achieve maximum power point tracking (MPPT) control of photovoltaic cells and constant voltage or constant current charging control of batteries.

[0124] Therefore, the embodiment of the present application determines the second modulation signal through the control variables generated by the first controller 331, the second controller 332 and the third controller 333, so that the buck-boost circuit 200 can adjust the power in response to the second modulation signal, thereby realizing MPPT control of the photovoltaic cell and constant voltage or constant current charge and discharge control of the battery. Therefore, the embodiment of the present application utilizes the primary duty cycle control module 330 to effectively improve the impact of the primary photovoltaic cell voltage fluctuation or the battery cell voltage fluctuation on the secondary load voltage, ensure the safety and stability of the multi-port converter, and improve the energy supply efficiency of the photovoltaic cell and the battery.

[0125] In some embodiments of the present application, Figure 5 As shown, the control unit 300 further includes a primary-secondary side phase shift control module 340 , and the primary-secondary side phase shift control module 340 includes a fourth controller 341 , a modulation strategy submodule 342 and a phase shift controller 343 .

[0126] The fourth controller 341 is configured to output a reference voltage V orefThe output voltage sampling value V o The difference between the values ​​generates the fourth control variable D f ;

[0127] The modulation strategy submodule 342 is configured to generate a modulation strategy based on the output voltage sample value V of the multi-port converter 10. o , the input voltage sampling value V of the first port b The equivalent voltage gain M is determined by the transformation ratio n of the transformer T, and the working mode of the multi-port converter 10 is determined according to the equivalent voltage gain M, and the working mode and the fourth control variable D are determined according to the working mode. f Generate the fifth control variable D 1 and the sixth control variable D 2 , where the fourth control variable D f Characterizes the phase angle of the primary and secondary sides, the fifth control variable D 1 Characterizes the phase shift angle in the primary bridge arm, the sixth control variable D 2 Characterize the phase shift angle in the secondary bridge arm;

[0128] The phase shift controller 343 is configured to f , the fifth control variable D 1 and the sixth control variable D 2 A primary carrier signal and a secondary carrier signal are generated, wherein a phase difference exists between the primary carrier signal and the secondary carrier signal.

[0129] Further, Figure 6 The working process of the original secondary side phase shift control module 340 is shown, including the following steps:

[0130] Step S21, determine the fourth control variable D f , where -0.b≤D f ≤0.5. Specifically, the output reference voltage V oref The output voltage sampling value V o The voltage error is obtained by subtracting the voltage error, and the fourth controller 341 outputs the fourth control variable D f , where the fourth control variable D f Refers to the ratio of the phase difference between the neutral line of the full-bridge square wave on the primary side and the secondary side of the multi-port converter and 180 degrees. The external phase angle control can adjust the phase relationship between the primary side and the secondary side, thereby controlling the direction and magnitude of energy flow. Therefore, when the external phase angle is adjusted, it will directly affect the phase difference between the neutral line of the full-bridge square wave on the primary side and the secondary side. Therefore, the embodiment of the present application uses the fourth control variable D f Introduce external phase angle control.

[0131] It should be noted that, in some embodiments of the present application, the fourth control variable D fThe size of the fourth control variable D is between -0.5 and 0.5. f If it is greater than 0.5, the fourth control variable D f Equal to 0.5, if the fourth control variable D f is less than -0.5, then the fourth control variable D f Equal to -0.5.

[0132] Step S22: Model the DAB converter using the circuit averaging method and define the equivalent voltage gain as M=V o / nV b , n is the transformer ratio, and according to the equivalent voltage gain M and the fourth control variable D f The size of the corresponding fifth control variable D 1 and the sixth control variable D 2 .

[0133] In the embodiment of the present application, the dual active bridge circuit 100 is determined to be in boost mode or buck mode according to the size of the equivalent voltage gain M, and the fourth control variable D f Calculate the fifth control variable D corresponding to the light load condition and the heavy load condition in the boost mode respectively 1 and the sixth control variable D 2 , or the fifth control variable D corresponding to the light load and heavy load conditions in the buck mode 1 and the sixth control variable D 2 Then take the fifth control variable D 1 and the sixth control variable D 2 The calculation result and the minimum value of the preset constants are used as the fifth control variable D finally determined. 1 and the sixth control variable D 2 , to achieve smooth switching between modes.

[0134] Therefore, the fourth control variable D is used in the embodiment of the present application. f Characterize the phase angle of the primary and secondary sides, and use the fifth control variable D 1 Characterize the phase shift angle in the primary bridge arm, and use the sixth control variable D 2 By characterizing the phase shift angle in the secondary bridge arm, two degrees of freedom of the phase shift angles in the primary and secondary bridge arms are introduced, which realizes the optimized control of the ZVS performance and inductor current stress of the multi-port converter, improves the operating performance of the multi-port converter in different scenarios, and solves the problem of increased losses caused by the mismatch between the primary and secondary voltages during the primary duty cycle adjustment process.

[0135] Specifically, further, Figure 6 As shown, step S22 includes the following steps:

[0136] Step S221, sampling Vb and V o Calculate the equivalent voltage gain M;

[0137] Step S222, determine whether the equivalent voltage gain M is less than or equal to 1, if so, execute step S223, if not, execute step S224. Specifically, if M≤1, it corresponds to mode 1 and mode 2, wherein FIG7(a) shows the corresponding signal waveform when the multi-port converter 10 works in mode 1, and mode 1 represents the buck mode of the DAB circuit under light load, and FIG7(b) shows the corresponding signal waveform when the multi-port converter 10 works in mode 2, and mode 2 represents the buck mode of the DAB circuit under heavy load. If M>1, it corresponds to mode 3 and mode 4, wherein FIG7(c) shows the corresponding signal waveform when the multi-port converter 10 works in mode 3, and mode 3 represents the boost mode of the DAB circuit under light load, and FIG7(d) shows the corresponding signal waveform when the multi-port converter 10 works in mode 4, and mode 4 represents the boost mode of the DAB circuit under heavy load. Wherein, v AB is the voltage between node A and node B, v CD is the voltage value between node C and node D, i LK represents the freewheeling current of the third inductor Lk.

[0138] Step S223, calculate the fifth control variable D according to the following formula (1): 1 and the sixth control variable D 2 for:

[0139]

[0140] Where D 1_Mode1 is the fifth control variable corresponding to mode 1, D 1_Mode2 is the fifth control variable corresponding to mode 2, n is the transformer ratio, L k is the inductance value of the third inductor, I ZVS2 is the minimum current required for the secondary side full bridge to achieve zero voltage switching, V o The multi-port converter 10 provides an output voltage Vo to the load, T s is the conduction period of the multi-port converter 10.

[0141] Step S224, calculate the fifth control variable D according to the following formula (2): 1 and the sixth control variable D 2 for:

[0142]

[0143] Where D 2_Mode3 is the sixth control variable corresponding to mode 3, D2_Mode4 is the sixth control variable corresponding to mode 4, I ZVS1 is the minimum current required for the primary side full bridge to achieve zero voltage switching, V b is the input voltage of the first port.

[0144] Specifically, the fifth control variable D corresponding to mode 1 is 1_Mode1 and the sixth control variable D 2_Mode1 Determined as follows:

[0145]

[0146] The fifth control variable D corresponding to mode 2 1_Mode2 and the sixth control variable D 2_Mode2 Determined as follows:

[0147]

[0148] The fifth control variable D corresponding to mode 3 1_Mode3 and the sixth control variable D 2_Mode3 Determined as follows:

[0149]

[0150] The fifth control variable D corresponding to mode 4 1_Mode4 and the sixth control variable D 2_Mode4 Determined as follows:

[0151]

[0152] Step S23: set the fourth control variable D f , the fifth control variable D 1 and the sixth control variable D 2 The phase shift controller outputs four groups of carrier signals with phase differences, including the primary carrier signal μ tril1 , primary carrier signal μ tril2 , secondary carrier signal μ tril3 And the secondary carrier signal μ tril4 And send these carrier signals to the corresponding logic circuit to generate corresponding PWM signals.

[0153] Therefore, the embodiment of the present application realizes the voltage distribution of the primary and secondary sides through the primary and secondary side phase shift control module 340, and uses the fourth control variable D generated by the fourth controller 341 f The ratio of the phase difference between the neutral line of the full-bridge square wave on the primary side and the secondary side of the multi-port converter and 180 degrees is represented, so that on the basis of the external shift phase angle control, the fifth control variable D generated by the modulation strategy submodule is used1 and the sixth control variable D 2 Two degrees of freedom are provided, namely the phase shift angle within the primary bridge arm and the phase shift angle within the secondary bridge arm, and the primary carrier signal and the secondary carrier signal are generated respectively through the phase shift controller 343 to achieve precise matching of the primary and secondary voltages, thereby greatly reducing the risk of increased losses due to mismatch between the primary and secondary voltages, optimizing the ZVS performance of the multi-port converter, and optimizing the control of the inductor current stress, thereby improving the operating performance of the multi-port converter in different scenarios.

[0154] In some embodiments of the present application, Figure 1 As shown, the dual active bridge circuit 100 further includes a rectifier bridge, and the rectifier bridge is connected to the secondary coil of the transformer T. Specifically, the rectifier bridge includes a switch tube S 7 , switch tube S 8 , switch tube S 9 And the switch tube S 10 The H bridge consists of a switch tube S 7 The source and switch tube S 8 The drain of the switch tube S has a third node C. 9 The source and switch tube S 10 The drain of has a third node D.

[0155] Furthermore, the control unit 300 further includes a second logic circuit 350, wherein the second logic circuit 350 is configured to generate a signal according to the secondary carrier signal μ tril3 , secondary carrier signal μ tril4 and the third modulation signal μ ctrl3 Control the switch tube of the rectifier bridge.

[0156] It should be noted that the above-mentioned rectifier bridge includes a third bridge arm and a fourth bridge arm, and the third bridge arm and the fourth bridge arm respectively include a fourth switch tube and a fifth switch tube, wherein the fourth switch tube can be a switch tube S 7 And switch tube S 9 The fifth switch tube can be a switch tube S 8 And switch tube S 10 .

[0157] The second logic circuit 350 generates a fourth PWM signal for controlling the fourth switch tube and a fifth PWM signal for controlling the fifth switch tube, respectively. The fourth PWM signal may be a PWM signal V GS7 and PWM signal V GS9 , the fifth PWM signal may be a PWM signal V GS8 and PWM signal V GS10 .

[0158] Specifically, Figure 5As shown, the switch tube S of the corresponding rectifier bridge 7 And switch tube S 8 The third bridge arm is provided with a second logic circuit 350 , and the second logic circuit 350 includes a third comparator 351 and a second inverter 352 .

[0159] The negative input terminal of the third comparator 351 is suitable for receiving the secondary carrier signal μ tril3 The positive input terminal of the third comparator 351 is suitable for receiving the third modulation signal μ ctrl3 The output terminal of the third comparator 351 is suitable for outputting a PWM signal V GS7 The input end of the second inverter 352 is connected to the output end of the third comparator 351, and the output end of the second inverter 352 is suitable for outputting a PWM signal V GS8 ;

[0160] Among them, the PWM signal V GS7 Used to control the switch tube S of the rectifier bridge 7 , PWM signal V GS8 Used to control the switch tube S of the rectifier bridge 8 .

[0161] Similarly, the switch tube S corresponding to the rectifier bridge 9 And switch tube S 10 The bridge arm is provided with a second logic circuit 350 , which includes a third comparator 353 and a second inverter 354 .

[0162] The negative input terminal of the third comparator 353 is suitable for receiving the secondary carrier signal μ tril4 The positive input terminal of the third comparator 353 is suitable for receiving the third modulation signal μ ctrl3 The output terminal of the third comparator 353 is suitable for outputting a PWM signal V GS9 The input end of the second inverter 354 is connected to the output end of the third comparator 353, and the output end of the second inverter 354 is suitable for outputting a PWM signal V GS10 ;

[0163] Among them, the PWM signal V GS9 Used to control the switch tube S of the rectifier bridge 9 , PWM signal V GS10 Used to control the switch tube S of the rectifier bridge 10 .

[0164] Accordingly, if Figure 8 As shown, the embodiment of the present application further provides a multi-port converter 1, wherein the multi-port converter comprises:

[0165] A first power source 20;

[0166] A second power source 30;

[0167] And the multi-port converter 10 according to the above embodiment, wherein the multi-port converter 10 includes a first port, a second port and an output port, and the first port of the multi-port converter 10 is connected to the first power supply 20, and the second port of the multi-port converter 10 is connected to the second power supply 30.

[0168] The specific configuration of each of the above modules and units and further functional description are the same as those of the above corresponding embodiments and will not be repeated here.

[0169] The multi-port converter 1 proposed in the embodiment of the present application utilizes the multi-port converter 10 to perform voltage regulation on the first power supply 20 and the second power supply 30, and realizes power decoupling control of the first port and the second port through the multi-port converter 10, so that the duty cycle control of the switch tubes on the corresponding lines of the first port and the second port do not interfere with each other, and realizes power decoupling control while the first power supply 20 and the second power supply 30 work in coordination, and then effectively avoids the influence of the duty cycle adjustment of the switch tube on the load voltage by independently adjusting the input voltages of the two ports, so that it can adapt to power supply equipment with wide fluctuations, greatly improve the stability of the multi-port converter, and expand the scope of application of the multi-port converter.

[0170] For the convenience of description, the above device is described in various units according to their functions. Of course, when implementing the present application, the functions of each unit can be implemented in the same or multiple software and / or hardware.

[0171] It should also be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, commodity or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, commodity or device. In the absence of more restrictions, the elements defined by the sentence "comprises a ..." do not exclude the existence of other identical elements in the process, method, commodity or device including the elements.

[0172] The various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referenced to each other, and each embodiment focuses on the differences from other embodiments.

[0173] The above is only an embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the scope of the claims of the present application.

[0174] Although the embodiments of the present application have been described in conjunction with the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present application, and such modifications and variations are all within the scope defined by the appended claims.

Claims

1. A multi-port converter based on a decoupling control topology, characterized in that: The multi-port converter comprises: a first port, a second port, and an output port; A dual active bridge circuit, wherein the dual active bridge circuit is configured to perform bidirectional energy conversion on the first port and the output port, wherein the dual active bridge circuit comprises a transformer, the primary side of the transformer comprises a first bridge arm and a second bridge arm, and the first bridge arm and the second bridge arm each comprise three switch tubes; a buck-boost circuit, the buck-boost circuit being configured to regulate the input voltage of the second port and send the regulated voltage to the first port, wherein the buck-boost circuit and the dual active bridge circuit share the switch tubes on the first bridge arm and the second bridge arm; A control unit, the control unit is configured to control the on and off of the switch tubes on the first bridge arm and the second bridge arm, and control the duty cycle of the dual active bridge circuit according to the on time of the target switch tubes in the first bridge arm and the second bridge arm respectively, and control the duty cycle of the buck-boost circuit according to the simultaneous on time of an adjacent switch tube of the target switch tube and the target switch tube, so as to decouple the duty cycle of the dual active bridge circuit and the buck-boost circuit.

2. The multi-port converter according to claim 1, characterized in that: There is a phase difference between the turn-on timing of the switch tube on the first bridge arm and the turn-on timing of the switch tube on the second bridge arm.

3. The multi-port converter according to claim 1, characterized in that: The first bridge arm and the second bridge arm respectively include: A first switch tube, wherein a drain of the first switch tube is connected to a positive input terminal of the first port; a second switch tube, wherein a drain of the second switch tube is connected to a source of the first switch tube and has a first node; a third switch tube, wherein the drain of the third switch tube is connected to the source of the second switch tube and has a second node, the source of the third switch tube is respectively connected to the negative input end of the first port and the second port, and the third switch tube is configured as the target switch tube Wherein, the control unit controls the duty cycle of the dual active bridge circuit according to the conduction time of the third switch tube, and the conduction time of the third switch tube is a preset value; The control unit controls the duty cycle of the buck-boost circuit according to the simultaneous conduction time of the second switch tube and the third switch tube; The control unit determines the on-time of the first switch tube according to the on-time of both the second switch tube and the third switch tube.

4. The multi-port converter according to claim 3, characterized in that: The buck-boost circuit comprises: a first inductor, wherein a first end of the first inductor is connected to a positive input end of the second port, and a second end of the first inductor is connected to a first node on the first bridge arm; A second inductor, wherein a first end of the second inductor is connected to the positive input end of the second port, and a second end of the second inductor is connected to a first node on the second bridge arm.

5. The multi-port converter according to claim 3, characterized in that: The dual active bridge circuit also includes: a third inductor, wherein a first end of the third inductor is connected to a second node on the first bridge arm; A transformer, wherein the same-name end of the primary coil of the transformer is connected to the second end of the third inductor, and the opposite-name end of the primary coil of the transformer is connected to the second node on the second bridge arm.

6. The multi-port converter according to any one of claims 3 to 5, characterized in that: The control unit includes a first logic circuit, and the first bridge arm and the second bridge arm are respectively provided with corresponding first logic circuits, wherein the first logic circuit includes: A first comparator, wherein a positive input terminal of the first comparator is suitable for receiving a first modulation signal, a negative input terminal of the first comparator is suitable for receiving a primary carrier signal, and an output terminal of the first comparator is suitable for outputting a third PWM signal, wherein the third PWM signal is used to control the third switch tube; A second comparator, wherein a positive input terminal of the second comparator is adapted to receive a second modulation signal, and a negative input terminal of the second comparator is adapted to receive the primary carrier signal; A first inverter, wherein an input end of the first inverter is connected to an output end of the second comparator, and an output end of the first inverter is suitable for outputting a second PWM signal, wherein the second PWM signal is used to control the second switch tube; A first XOR gate, wherein a first input terminal of the first XOR gate is connected to an output terminal of the first comparator, a second input terminal of the first XOR gate is connected to an output terminal of the first inverter, and an output terminal of the first XOR gate is suitable for outputting a first PWM signal, wherein the first PWM signal is used to control the first switch tube.

7. The multi-port converter according to claim 6, characterized in that: The first port is connected to a storage battery, and the second port is connected to a photovoltaic cell; The control unit further includes a primary duty cycle control module, and the primary duty cycle control module includes: A first controller, wherein the first controller is configured to perform maximum power point tracking control on the photovoltaic cell and generate a first control variable; a second controller configured to perform constant voltage charge and discharge control on the battery and generate a second control variable; a third controller configured to perform constant current charge and discharge control on the battery and generate a third control variable; A modulation module is configured to determine a minimum value among the first control variable, the second control variable and the third control variable, and generate the second modulation signal according to the minimum value.

8. The multi-port converter according to claim 6, characterized in that: The control unit further includes a primary-secondary side phase shift control module, and the primary-secondary side phase shift control module includes: a fourth controller configured to generate a fourth control variable according to a difference between an output reference voltage and an output voltage sampling value of the multi-port converter; A modulation strategy submodule, the modulation strategy submodule is configured to determine an equivalent voltage gain according to an output voltage sampling value of the multi-port converter, an input voltage sampling value of the first port, and a transformation ratio of the transformer, and determine an operating mode of the multi-port converter according to the equivalent voltage gain, and generate a fifth control variable and a sixth control variable according to the operating mode and the fourth control variable, wherein the fourth control variable represents an external phase shift angle of a primary-secondary side, the fifth control variable represents an internal phase shift angle of a primary-side bridge arm, and the sixth control variable represents an internal phase shift angle of a secondary-side bridge arm; A phase-shift controller, wherein the phase-shift controller is configured to generate the primary carrier signal and the secondary carrier signal according to the fourth control variable, the fifth control variable and the sixth control variable, wherein there is a phase difference between the primary carrier signal and the secondary carrier signal.

9. The multi-port converter according to claim 8, characterized in that: The dual active bridge circuit also includes a rectifier bridge, and the rectifier bridge is connected to the secondary coil of the transformer; The control unit further includes a second logic circuit, wherein the second logic circuit is configured to control the switch tube of the rectifier bridge according to the secondary carrier signal and the third modulation signal; Wherein, the second logic circuit comprises: a third comparator, wherein a negative input terminal of the third comparator is adapted to receive the secondary carrier signal, a positive input terminal of the third comparator is adapted to receive the third modulation signal, and an output terminal of the third comparator is adapted to output a fourth PWM signal; a second inverter, wherein an input terminal of the second inverter is connected to an output terminal of the third comparator, and an output terminal of the second inverter is suitable for outputting a fifth PWM signal; The fourth PWM signal and the fifth PWM signal are used to control the switch tube of the rectifier bridge.

10. A power supply system, characterized in that: The power supply system comprises: First power source; Second power supply; And a multi-port converter according to any one of claims 1 to 9 above, wherein the multi-port converter comprises a first port, a second port and an output port, and the first port of the multi-port converter is connected to the first power supply, and the second port of the multi-port converter is connected to the second power supply.

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