A Four-Port Energy Routing Topology and Control Strategy Based on Partial Power Conversion

Abstract

The present invention discloses a four-port energy routing topology based on partial power conversion technology, which ensures isolation of each port by means of a high-frequency transformer T. It includes the main parts of four full-bridge structures on the primary side, photovoltaic side, fuel cell side, and battery side, as well as a photovoltaic cell, a reversible solid oxide cell, a battery, and three DC buses with different voltage levels. Each port structure includes a phase-shifting inductor, four power switching tubes, anti-parallel diodes, and a port capacitor. The primary side adopts a battery reuse structure, and the three secondary sides are respectively connected to a group of battery modules and a DC bus to form their respective partial power conversion structures, and a current ripple suppression inductor is added to the output stage of each battery. The present invention realizes functions such as photovoltaic maximum power tracking, fuel cell bidirectional transmission, and lithium battery charging and discharging with a smaller power level adjustment after establishing the partial power conversion technology structures by sharing the battery as a common energy input and output port.

Description

Technical Field

[0001] The present invention relates to the fields of energy Internet and application of power electronics technology, and in particular to an integrated multi-port energy routing topology and control strategy based on partial power conversion technology. Background Art

[0002] In order to alleviate the energy crisis and accelerate the development of renewable energy power generation technology, the energy router, as a key technology of the energy Internet, has received increasing attention and research. The energy router can not only act as a traditional transformer to achieve voltage conversion, but also provide fault isolation and power quality management. At the same time, it can intelligently identify and manage the connected loads, and optimize the distribution of electric energy in a region, which can better alleviate the energy crisis and environmental protection pressure.

[0003] In the world energy structure, electricity and its related industries are the main driving forces for achieving low-carbonization. Distributed renewable energy technologies such as solar energy and wind energy have continuously developed from explosive growth to the stage of improving quality and efficiency. At the same time, due to the characteristics of high calorific value, high energy density, clean combustion, and multiphase storage of hydrogen energy, it has gradually become the key and important carrier in the clean energy stage. The use of electrolytic hydrogen production and fuel cells is the key technology for hydrogen energy storage to achieve the mutual conversion of hydrogen energy and electric energy. The reversible solid oxide battery is a type of fuel cell, which is characterized in that it can operate in the discharge mode like a fuel cell or in the charging mode like an electrolytic cell, and has lower electrochemical losses compared with other fuel cells.

[0004] In order to realize the comprehensive utilization of the above several kinds of energy, integration needs to be carried out through an electric power converter. Among power conversion devices, the characteristic of full power conversion is that all the power of the conversion object is transmitted to the power grid through itself. The efficiency of this converter has reached a very high value and it is difficult to further improve the efficiency. Therefore, some scholars have proposed to use partial power conversion to further improve the power and efficiency of energy transmission. In addition, besides the differences in power and overall system efficiency, when connecting various distributed energy sources, the bi-directional DC / DC converter needs to consider the positive and negative polarities of input and output, which is not conducive to the further expansion of the system. And with the continuous improvement of the functional requirements for the energy routing system, single-stage converters can no longer meet the needs, while the higher the number of stages of the converter, the more difficult it is to improve the efficiency and reliability. Therefore, partial power conversion technology can be added to the overall system to effectively connect various distributed energy sources to the common DC bus, and then the stability operation and function realization of the system can be ensured through the closed-loop control of this converter. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a control strategy for a four-port energy routing topology based on partial power conversion technology, effectively utilize various distributed energy sources, achieve electrical isolation through a four-port structure, adopt partial power conversion technology to improve the efficiency of the overall topology, and connect to multiple groups of DC buses with different voltage levels to enhance the scalability of the system.

[0006] To solve the above technical problems, the technical solution adopted by the present invention is: a four-port energy routing topology based on partial power conversion technology, which ensures isolation of each port with a high-frequency transformer T, including the primary side, photovoltaic side, fuel cell side, and battery side, which are the main parts of four full-bridge structures, as well as photovoltaic cells, reversible solid oxide cells, batteries, and three groups of DC buses Bus 1 、Bus 2 、Bus 3 . Each port structure includes phase-shifting inductors L S 、L P 、L r 、L B , four power switch tubes Q 1 、Q 2 、Q 3 、Q 4 , anti-parallel diodes D 1 、D 2 、D 3 、D 4 and port capacitors C S 、C P 、C r 、C B ; the primary side adopts a battery reuse structure, and the three secondary sides are respectively connected to a group of battery modules and a DC bus. The photovoltaic side is connected to the photovoltaic cells and Bus 1 , the rSOC side is connected to rSOC and Bus 2 , the battery side is connected to the battery and Bus 3 , constituting their respective partial power conversion structures, and a current ripple suppression inductor L Pout 、L rout 、L Bout is added to the output stage of each battery.

[0007] A further improvement of the technical solution of the present invention lies in: in the four-port full-bridge structure, the primary side includes a first power switch tube Q 1S 、a second power switch tube Q 2S 、a third power switch tube Q 3S 、a fourth power switch tube Q 4S 、a first anti-parallel diode D 1S 、a second anti-parallel diode D 2S 、a third anti-parallel diode D3S , the fourth anti-parallel diode D 4S , the first capacitor C S , the high-frequency transformer T includes a first winding N S , a second winding N P , a third winding N r , a fourth winding N B . The collector of the first power switch Q 1S is connected to the collector of the third power switch Q 3S , the negative electrode of the first anti-parallel diode D 1S and the negative electrode of the third anti-parallel diode D 3S ; the emitter of the second power switch Q 2S is connected to the emitter of the fourth power switch Q 4S , the positive electrode of the second anti-parallel diode D 2S and the positive electrode of the fourth anti-parallel diode D 4S ; the emitter of the first power switch Q 1S is connected to the collector of the second power switch Q 2S ; the emitter of the third power switch Q 3S is connected to the collector of the fourth power switch Q 4S ; one end of the first capacitor C S is connected to the collector of the first power switch Q 1S , and the other end of the first capacitor C S is connected to the emitter of the second power switch Q 2S ; the same-name end of the first winding N S is first connected to the phase-shifting inductor L s , and then connected to the midpoint between the emitter of the first power switch Q 1S and the collector of the second power switch Q 2S , and the different-name end of the first winding N S is connected to the midpoint between the emitter of the third power switch Q 3S and the collector of the fourth power switch Q 4S . The hardware composition and connection structure on the photovoltaic side, rSOC side, and battery side are the same as those on the primary side, and the windings of each port are isolated by the high-frequency transformer T.

[0008] A further improvement of the technical solution of the present invention is that: the positive electrodes on the output sides of the ports on the photovoltaic side, rSOC side, and battery side are respectively connected to the current pulsation suppression inductors L Pout , L rout , L Bout and then connected to the negative electrodes of the photovoltaic cell, rSOC, and battery, and the positive electrodes of the photovoltaic cell, rSOC, and battery are respectively connected to the DC bus Bus 1 , Bus2 and the positive pole of Bus 3 are connected. The negative poles of the output sides of the ports on the photovoltaic side, rSOC side, and battery side are respectively connected to the negative poles of Bus 1 and Bus 2 and Bus 3 . The negative poles of Bus 1 and Bus 2 and Bus 3 are respectively grounded by three groups of GND 1 and GND 2 and GND 3 respectively, jointly constituting their respective partial power conversion structures. The positive pole of the port on the primary side is connected to the positive pole of the battery and the positive pole of Bus 3 , and the negative pole of the port on the primary side is connected to the negative pole of the battery and the current ripple suppression inductor L Bout .

[0009] A further improvement of the technical solution of the present invention lies in that: the four-port structure integrates various clean energies, namely photovoltaic, fuel cell, and battery, on the basis of a four-active-bridge converter, and forms a partial power conversion structure at each port. By adding various distributed energies and partial power conversion technologies, the power level that needs to be processed by the four-port converter is reduced. Electrical isolation of each port is achieved through a full-bridge structure and a high-frequency transformer. Through the phase-shifting inductors L S and L P and L r and L B , it is ensured that each port can achieve phase-shift control, jointly ensuring the stability and multi-directional transmission of energy.

[0010] A further improvement of the technical solution of the present invention lies in that: for a control strategy of a four-port energy routing topology based on partial power conversion technology, for the control of each port, different methods are used to obtain the regulated target sampling values for each port. The sampling values and reference values are processed by a PI regulator, and the phase-shift duty ratio between bridges is output. Then, after amplitude limiting, the control signal is transmitted to a single-phase-shift control module to form a driving signal to the target switching tube, realizing the stability of the control target.

[0011] A further improvement of the technical solution of the present invention lies in that: the circulating average power equation derived from a dual-active full-bridge converter can be extended to a four-active-bridge converter. Therefore, the analysis of the overall topology of the four ports can be decomposed into three groups of dual-active converters for analysis and power control. Moreover, the dual-active converter has the advantages of a relatively small overall system inertia and easy implementation of soft switching under phase-shift control. Therefore, three groups of phase-shift control between bridges are respectively adopted to control the three secondary ports, which can ensure the stable operation of each port.

[0012] A further improvement of the technical solution of the present invention lies in: The specific control steps for each port are as follows:

[0013] 1) For the primary side and battery side structures with battery source-level multiplexing, the port voltage on the battery side is controlled to be constant. When the battery is discharging, the potential difference between the Bus 3 bus and the output voltage of the battery is used as the reference value of the port voltage on the battery side and input to the control module. Then, through the PI regulator and SPS, the control output drive signal is sent to all the switching tubes on the primary side and the battery side, so as to establish the PPC structure of the port on the battery side and keep the port voltage constant at this reference value.

[0014] 2) For the port on the photovoltaic side, after the photovoltaic cell model is determined, its various parameters are already determined. According to the partial power conversion structure on the photovoltaic side, in order to ensure that the photovoltaic cell array operates at the maximum power point, first, the output voltage U PV and current I PV of the photovoltaic cell are monitored. Through the maximum power point tracking technology (maximum power point tracker, MPPT), the voltage U m at the maximum power point of the photovoltaic cell is obtained. Then, the voltage of the port on the photovoltaic side is controlled. The potential difference between the Bus 1 bus voltage and the photovoltaic cell U m is used as the reference value of the port voltage on the photovoltaic side. Through the PI regulator and SPS, the control output drive signal is sent to the switching tubes on the photovoltaic side, and the port voltage on the photovoltaic side is kept constant at this reference value, so as to enable the photovoltaic cell to transmit power to the Bus 1 bus at the maximum power, improving the energy transmission efficiency of this port. Since the drive signal of the switching tubes on the primary side has been given when controlling the port voltage on the battery side, only the drive signal of the switching tubes on the photovoltaic side needs to be given to achieve the control goal of this port.

[0015] 3) The control of the port on the rSOC side is different from that of the other ports. Due to the difference in battery characteristics, the charge and discharge state of rSOC and the battery current I rSOC are controlled on the rSOC side port. After determining the charge and discharge working state of rSOC, a suitable reference value of the rSOC current can be given, and then through the PI regulator and SPS control, I rSOC is kept constant at this reference value, so as to establish the partial power conversion structure of this port and ensure the stable operation of rSOC. During the control process of the rSOC side, the drive signal output by the controller only needs to be sent to the switching tubes on the rSOC side to achieve the control goal of this port. Description of the Drawings

[0016] Figure 1 is the electrical schematic diagram of a four-port energy routing topology based on partial power conversion technology of the present invention;

[0017] Figure 2 is the electrical structure diagram of the PV side port based on the partial power conversion technology of the present invention;

[0018] Figure 3 is the electrical structure diagram of the rSOC side port based on the partial power conversion technology of the present invention;

[0019] Figure 4 is the electrical structure diagram of the battery side port based on the partial power conversion technology of the present invention;

[0020] Figure 5 is the electrical schematic diagram of an equivalent dual active bridge topology of the present invention;

[0021] Figure 6 is the waveform diagram of the working principle of an equivalent dual active bridge topology operating in the forward single phase shift modulation state of the present invention;

[0022] Figure 7 is the waveform diagram of the working principle of an equivalent dual active bridge topology operating in the reverse single phase shift modulation state of the present invention;

[0023] Figure 8 is the schematic diagram of the control strategy of the primary side and the battery side in the four-port energy routing topology based on the partial power conversion technology of the present invention;

[0024] Figure 9 is the schematic diagram of the control strategy of the PV side in the four-port energy routing topology based on the partial power conversion technology of the present invention;

[0025] Figure 10 is the schematic diagram of the control strategy of the rSOC side in the four-port energy routing topology based on the partial power conversion technology of the present invention;

[0026] wherein, PV cell is a photovoltaic cell, rSOC is a reversible solid oxide cell, and Battery is a battery; T is a high-frequency transformer, N S 、N P 、N r 、N B are the first, second, third, and fourth windings; Bus 1 、Bus 2 、Bus 3 are the first, second, and third DC buses; GND 1 、GND 2 、GND 3 are the first, second, and third ground poles; C S 、C P 、C r 、C Bare the first, second, third, and fourth capacitors; L S , L P , L r , L B are the first, second, third, and fourth phase-shifting inductors; L Pout , L rout , L Bout are the first, second, and third battery current smoothing inductors; Q 1S , Q 2S , Q 3S , Q 4S are the first, second, third, and fourth primary-side power switching transistors, D 1S , D 2S , D 3S , D 4S are the first, second, third, and fourth anti-parallel diodes on the primary side; Q 1P , Q 2P , Q 3P , Q 4P are the first, second, third, and fourth power switching transistors on the PV side, D 1P , D 2P , D 3P , D 4P are the first, second, third, and fourth anti-parallel diodes on the PV side; Q 1r , Q 2r , Q 3r , Q 4r are the first, second, third, and fourth power switching transistors on the rSOC side, D 1r , D 2r , D 3r , D 4r are the first, second, third, and fourth anti-parallel diodes on the rSOC side; Q 1B , Q 2B , Q 3B , Q 4B are the first, second, third, and fourth power switching transistors on the battery side, D 1B , D 2B , D 3B , D 4B are the first, second, third, and fourth anti-parallel diodes on the battery side; V PV , V rSOC , V Bat are the output voltages of the PV cells, rSOC, and battery; I PV , I rSOC , I Bat are the output currents of the PV cells, rSOC, and battery; V Bus1 , V Bus2 , V Bus3 are the first, second, and third DC bus voltages; V L1 , V L2 , V L3are the output voltage values of the DC / DC converters on the photovoltaic side, rSOC side, and battery side; S 1 and S 2 and S 3 and S 4 are the first, second, third, and fourth power switch tubes on the primary side of the dual-active-bridge converter topology, D 1 and D 2 and D 3 and D 4 are the first, second, third, and fourth anti-parallel diodes on the primary side of the dual-active-bridge converter topology; S 5 and S 6 and S 7 and S 8 are the fifth, sixth, seventh, and eighth power switch tubes on the secondary side of the dual-active-bridge converter topology, D 5 and D 6 and D 7 and D 8 are the fifth, sixth, seventh, and eighth anti-parallel diodes on the secondary side of the dual-active-bridge converter topology; V 1 and C 1 and L 1 and N 1 are the first power supply, first capacitor, first phase-shifting inductor, and first winding on the primary side of the dual-active-bridge converter topology, V 2 and C 2 and N 2 are the second power supply, second capacitor, and second winding on the secondary side of the dual-active-bridge converter topology; T D is the high-frequency transformer of the dual-active-bridge converter, and n is the turns ratio of the high-frequency transformer of the dual-active-bridge converter; T s is a switching period of the dual-active-bridge converter, T hs is half of the switching period, and D is the ratio between the phase-shift angle and π; U port_PV and U port_Bat are the port voltages on the photovoltaic side and the battery side; U port_PV,ref and I rSOC,ref and U port_Bat,ref are the reference value of the port voltage on the photovoltaic side, the reference value of the rSOC current, and the reference value of the port voltage on the battery side. Detailed implementation mode

[0027] The present invention will be further described in detail below with reference to the embodiments:

[0028] As Figure 1 shown, a four-port energy routing topology based on partial power conversion technology. In the four-port full-bridge structure, the primary side includes the first power switch tube Q 1S the second power switch tube Q 2S the third power switch tube Q 3S the fourth power switch tube Q4S , the first antiparallel diode D 1S , the second antiparallel diode D 2S , the third antiparallel diode D 3S , the fourth antiparallel diode D 4S , the first capacitor C S , the high-frequency transformer T includes a first winding N S , a second winding N P , a third winding N r , a fourth winding N B . The collector of the first power switch tube Q 1S is connected to the collector of the third power switch tube Q 3S , the cathode of the first antiparallel diode D 1S and the cathode of the third antiparallel diode D 3S ; the emitter of the second power switch tube Q 2S is connected to the emitter of the fourth power switch tube Q 4S , the anode of the second antiparallel diode D 2S and the anode of the fourth antiparallel diode D 4S ; the emitter of the first power switch tube Q 1S is connected to the collector of the second power switch tube Q 2S ; the emitter of the third power switch tube Q 3S is connected to the collector of the fourth power switch tube Q 4S ; one end of the first capacitor C S is connected to the collector of the first power switch tube Q 1S , and the other end of the first capacitor C S is connected to the emitter of the second power switch tube Q 2S ; the same-name end of the first winding N S is first connected to the phase-shifting inductor L s , and then connected to the midpoint between the emitter of the first power switch tube Q 1S and the collector of the second power switch tube Q 2S , and the different-name end of the first winding N S is connected to the midpoint between the emitter of the third power switch tube Q 3S and the collector of the fourth power switch tube Q 4S . The hardware composition and connection structure on the photovoltaic side, rSOC side and battery side are the same as those on the primary side. The windings of each port are electrically isolated from the high-frequency transformer through a full-bridge structure, and the phase-shifting control of each port is ensured through the first, second, third, and fourth phase-shifting inductors L S , L P , L r , L B , jointly ensuring the stability and multi-directional transmission of energy.

[0029] The positive electrodes of the port output sides of the photovoltaic side, rSOC side, and battery side are respectively connected to the first, second, and third battery current ripple suppression inductors L Pout , L rout , L Bout , and then connected to the negative electrodes of the photovoltaic cell, rSOC, and battery. The positive electrodes of the photovoltaic cell, rSOC, and battery are then respectively connected to the positive electrodes of the first, second, and third DC buses Bus 1 , Bus 2 , Bus 3 . The negative electrodes of the port output sides of the photovoltaic side, rSOC side, and battery side are respectively connected to the negative electrodes of the DC buses Bus 1 , Bus 2 , Bus 3 to form their respective partial power conversion structures. The positive electrode of the port on the primary side is connected to the positive electrode of the battery and the positive electrode of the DC bus Bus 3 , and the negative electrode of the port on the primary side is connected to the negative electrode of the battery and the current ripple suppression inductor L Bout .

[0030] As Figure 2 shown, establish the partial power conversion structure of the photovoltaic side. By adjusting the output voltage V PV of the photovoltaic cell, the output current I PV of the photovoltaic cell, and the output voltage value V L1 of the DC / DC converter on the photovoltaic side, ensure that the photovoltaic cell operates stably at the maximum power point, so as to achieve efficient energy transfer from the port on the photovoltaic side to the first DC bus Bus 1 .

[0031] As Figure 3 shown, establish the partial power conversion structure of the rSOC side. By adjusting the charge and discharge working mode of the rSOC, the input and output voltage V rSOC of the rSOC, the input and output current I rSOC of the rSOC, and the port voltage value V L2 of the DC / DC converter on the rSOC side, ensure that the rSOC operates in a stable state, so as to achieve energy interaction between the port on the rSOC side and the second DC bus Bus 2 .

[0032] As Figure 4 shown, establish the partial power conversion structure of the battery side. By adjusting the charge and discharge working mode of the battery, the input and output voltage V Battery of the battery, the input and output current I Battery of the battery, and the port voltage value V L3, ensure that the battery operates in a stable state, thereby realizing energy interaction among the battery-side port, the primary-side port, and the third DC bus 3 Perform energy interaction.

[0033] As Figure 5 shown, establish a dual-active-bridge topology structure. In the dual-active-bridge structure, the primary side includes the first power switch tube S 1 of the dual-active-bridge converter, the second power switch tube S 2 , the third power switch tube S 3 , the fourth power switch tube S 4 , the first anti-parallel diode D 1 , the second anti-parallel diode D 2 , the third anti-parallel diode D 3 , the fourth anti-parallel diode D 4 , the first power supply V 1 , the first capacitor C 1 , and the high-frequency transformer T D , and the turns ratio of the high-frequency transformer T D is n:1. The collector of the first power switch tube S 1 is connected to the collector of the third power switch tube S 3 , the cathode of the first anti-parallel diode D 1 and the cathode of the third anti-parallel diode D 3 ; the emitter of the second power switch tube S 2 is connected to the emitter of the fourth power switch tube S 4 , the anode of the second anti-parallel diode D 2 and the anode of the fourth anti-parallel diode D 4 ; the emitter of the first power switch tube S 1 is connected to the collector of the second power switch tube S 2 ; the emitter of the third power switch tube S 3 is connected to the collector of the fourth power switch tube S 4 ; the positive pole of the first power supply V 1 , one pole of the first capacitor C 1 is connected to the collector of the first power switch tube S 1 , and the negative pole of the first power supply V 1 , the other pole of the first capacitor C 1 is connected to the emitter of the second power switch tube S 2 ; the same-name end of the first winding N 1 is first connected to the phase-shifting inductor L 1 , and then connected to the midpoint A of the emitter of the first power switch tube S 1 and the collector of the second power switch tube S 2 , and the first winding N1 The opposite end is connected to the third power switch tube S 3 The emitter of the fourth power switch tube S 4 The collector midpoint B. The secondary side has only one less phase shift inductor L than the primary side. 1 , the connection method of the remaining components is the same as the original side.

[0034] like Figure 6 As shown in the figure, the working principle waveform diagram of the equivalent dual active bridge topology structure working in the forward single phase shift modulation state. Definition T s For a switching cycle, T hs The ratio between the phase shift angle and π is the phase shift angle D, DT hs Indicates the corresponding switch tube between the bridges (i.e. the first power switch tube S 1 The fifth power switch tube S 5 ) The switching signal has a phase difference, and the first power switch tube S on the primary side of the dual active bridge converter 1 With the fourth power switch tube S 4 The waveform is the same, the second power switch tube S 2 With the third power switch tube S 3 The waveform is also the same, and the first power switch tube S 1 , the fourth power switch tube S 4 Waveform and second power switch tube S 2 , the third power switch tube S 3 The waveforms are complementary. At this time, D>0, the dual active bridge converter works in the forward state, that is, the first power switch tube to the fourth power switch tube S of the dual active bridge converter 1 , S 2 , S 3 and S 4 The phase of the fifth power switch tube leads the eighth power switch tube S 5 , S 6 , S 7 and S 8 Phase DT hs The voltage peak between point A and point B is the first power supply voltage value V 1 , the voltage peak between point C and point D is the second power supply voltage value V 2 n times of .

[0035] like Figure 7 As shown, the equivalent dual active bridge topology structure works in the reverse single phase shift modulation state. At this time, D < 0, the dual active bridge converter works in the reverse state, that is, the first power switch tube to the fourth power switch tube S of the dual active bridge converter 1 , S 2 , S 3 and S 4lags behind the fifth to the eighth power switching tubes S 5 , S 6 , S 7 and S 8 by a phase DT hs . The voltage peak value between point A and point B is still the first power supply voltage value V 1 , and the voltage peak value between point C and point D is n times the second power supply voltage value V 2 .

[0036] As Figure 8 shown in the figure is the control strategy for the primary side and the battery side in the four-port energy routing topology based on the partial power conversion technology. For the primary side and the battery side with battery source level multiplexing, the port voltage of the battery side is controlled to be constant. If the battery is working in the discharging state, the potential difference between the battery output voltage and the third DC bus Bus 3 is used as the reference value of the port voltage of the battery side, and is input into the PI regulator and the SPS control module. After the control module processes the information, it outputs drive signals to each switching tube on the battery side and the primary side, so as to realize the establishment of the partial power conversion structure of the port of the battery side and the constant port voltage of the battery side to the reference value.

[0037] As Figure 9 shown in the figure is the control strategy for the photovoltaic side in the four-port energy routing topology based on the partial power conversion technology. After the photovoltaic cell model is determined, the parameters of the photovoltaic cell array are determined. To ensure that the photovoltaic cell array outputs the maximum power, the output voltage U PV and the output current I PV of the photovoltaic cell are sampled, and the voltage U m at the maximum power point of the photovoltaic cell is calculated through the photovoltaic cell maximum power tracker. Then, the potential difference between the voltage of the first DC bus Bus 1 and the voltage U m at the maximum power point of the photovoltaic cell is used as the reference value of the port voltage of the photovoltaic side, and then the PI regulator and the SPS control are used to output drive signals to the switching tubes on the photovoltaic side, so as to keep the port voltage of the photovoltaic side constant to this reference value.

[0038] As Figure 10 shown in the figure is the control strategy for the rSOC side in the four-port energy routing topology based on the partial power conversion technology. Due to the battery characteristic differences, for the control of the rSOC side port, the charge and discharge state of rSOC and the battery current I rSOC are controlled. After the charge and discharge working state of rSOC is determined, an appropriate reference value of the rSOC current can be given, and then I rSOC is kept constant to this reference value through the PI regulator and the SPS control, so as to realize the stable operation of the rSOC side port.

[0039] Based on partial power conversion technology, the present invention designs a four-port energy routing topology, which includes the main parts of four full-bridge structures on the primary side, photovoltaic side, fuel cell side and battery side, as well as photovoltaic cells, reversible solid oxide cells, batteries and three groups of DC buses with different voltage levels. With a high-frequency transformer as the center to ensure electrical isolation of each port, the primary side adopts a battery reuse structure. The three secondary sides are respectively connected to a group of battery modules and a DC bus to form their respective partial power conversion structures. And a current ripple suppression inductor is added to the output stage of each battery. According to the characteristics of each port, three sets of control strategies are designed based on phase-shift control to achieve stable operation of each port.

Claims

1. A four-port energy routing topology based on partial power conversion technology, Characterized in that: The high-frequency transformer T ensures isolation of each port, including four full-bridge structures on the primary side, photovoltaic side, fuel cell side, and battery side, as well as a photovoltaic cell, a reversible solid oxide cell, a battery, and three groups of mutually isolated DC buses Bus with different voltage levels. 1 、Bus 2 、Bus 3 and three groups of grounds GND 1 、GND 2 、GND 3 Each of the port structures includes a phase-shifting inductor L S 、L P 、L r 、L B 、four power switch tubes Q 1 、Q 2 、Q 3 、Q 4 ,antiparallel diodes D 1 、D 2 、D 3 、D 4 and port capacitors C S 、C P 、C r 、C B ; The primary side adopts a battery reuse structure. The three secondary sides are respectively connected to a group of battery modules and a DC bus. The photovoltaic side is connected to the photovoltaic cell and Bus 1 , the rSOC side is connected to rSOC and Bus 2 , and the battery side is connected to the battery and Bus 3 to form their respective partial power conversion structures. An inductor L for suppressing current ripple is added to the output stage of each battery Pout 、L rout 、L Bout ; In the four-port full-bridge structure, the primary side includes the first power switch tube Q 1S , the second power switch tube Q 2S , the third power switch tube Q 3S , the fourth power switch tube Q 4S , the first anti-parallel diode D 1S , the second anti-parallel diode D 2S , the third anti-parallel diode D 3S , the fourth anti-parallel diode D 4S , the first capacitor C S , and the high-frequency transformer T includes the first winding N S , the second winding N P , the third winding N r , the fourth winding N B ; The collector of the first power switch tube Q 1S is connected to the collector of the third power switch tube Q 3S , the cathode of the first anti-parallel diode D 1S and the cathode of the third anti-parallel diode D 3S ; The emitter of the second power switch tube Q 2S is connected to the emitter of the fourth power switch tube Q 4S , the anode of the second anti-parallel diode D 2S and the anode of the fourth anti-parallel diode D 4S ; The emitter of the first power switch tube Q 1S is connected to the collector of the second power switch tube Q 2S ; The emitter of the third power switch tube Q 3S is connected to the collector of the fourth power switch tube Q 4S ; One end of the first capacitor C S is connected to the collector of the first power switch tube Q 1S , and the other end of the first capacitor C S is connected to the emitter of the second power switch tube Q 2S ; The same-name end of the first winding N S is first connected to the phase-shifting inductor L s , and then connected to the midpoint between the emitter of the first power switch tube Q 1S and the collector of the second power switch tube Q 2S , and the different-name end of the first winding N S is connected to the midpoint between the emitter of the third power switch tube Q 3S and the collector of the fourth power switch tube Q 4S ; The hardware composition and connection structure of the photovoltaic side, rSOC side and battery side are the same as those of the primary side, and the windings of each port are isolated by the high-frequency transformer T; The positive poles of the port output sides of the photovoltaic side, rSOC side, and battery side are respectively connected to the current-shifting current pulsation suppression inductors L Pout , L rout , L Bout and then connected to the negative poles of the photovoltaic cell, rSOC, and battery. The positive poles of the photovoltaic cell, rSOC, and battery are respectively connected to the positive poles of the DC buses Bus 1 , Bus 2 , Bus 3 . The negative poles of the port output sides of the photovoltaic side, rSOC side, and battery side are respectively connected to the negative poles of the DC buses Bus 1 , Bus 2 , Bus 3 . The DC buses Bus 1 , Bus 2 , Bus 3 are respectively grounded by three different grounds GND 1 , GND 2 , GND 3 , jointly constituting their respective partial power conversion structures; the positive pole of the port on the primary side is connected to the positive poles of the battery and the DC bus Bus 3 , and the negative pole of the port on the primary side is connected to the negative pole of the battery and the current pulsation suppression inductor L Bout .

2. The four-port energy routing topology based on partial power conversion technology according to claim 1, Characterized in that: The four-port structure integrates various clean energies, namely photovoltaic, fuel cell and battery, on the basis of a four-active-bridge converter. In each port, a partial power conversion structure is constructed with distributed energy through each full-bridge structure. This structure realizes the function of reducing the overall system power level. Electrical isolation of each port is achieved through a high-frequency transformer structure. Through the phase-shifting inductors L S , L P , L r , L B phase-shift control can be achieved for each port, jointly ensuring the stable and multi-directional transmission of energy.

3. A control strategy for a four-port energy routing topology based on partial power conversion technology, Characterized in that: Based on the four-port energy routing topology according to any one of claims 1-2, it is proposed to determine the target reference value by using the maximum power point voltage determination and the photovoltaic side port voltage control for the photovoltaic side port, to determine the target reference value by using the rSOC current control for the rSOC side, and to determine the target reference value by using the port voltage control for the battery side. The bridge shift duty ratio is obtained by processing each sampled value and the target reference value through a PI regulator, and then the control signal is obtained through a limiting module and transmitted to the single-phase shift control module to form a drive signal to the target switch tube.

4. The control strategy for a four-port energy routing topology based on partial power conversion technology according to claim 3, Characterized in that: By extending the cyclic average power equation derived from the dual active bridge full-bridge converter to the four active bridge converter, the analysis and power control of the four-port overall topology are decomposed into three groups of dual active bridge converters, and three groups of bridge shift controls are respectively adopted to control each secondary side port to realize the stable operation of the overall system.

5. The control strategy for a four-port energy routing topology based on partial power conversion technology according to claim 3, Characterized in that: The specific control steps of each port are as follows: 1) For the primary side and the battery side of the battery source level multiplexing, the port voltage of the battery side is controlled to be constant; when the battery is discharging, the potential difference between the Bus 3 bus and the output voltage of the battery is used as the reference value of the port voltage of the battery side and input to the control module. Then, through the PI regulator and the SPS, the control output drive signal is sent to all the switching tubes on the primary side and the battery side to construct the port power conversion structure of the battery side and keep the port voltage constant at this reference value; 2) For the photovoltaic side port, the photovoltaic cell model and its various parameters are determined. According to the partial power conversion structure on the photovoltaic side, first, the output voltage U PV and current I PV of the photovoltaic cell are monitored, and the voltage U m at the maximum power point of the photovoltaic cell is obtained through the maximum power point tracking technology; then, the voltage of the photovoltaic side port is controlled. The potential difference between the Bus 1 bus voltage and the photovoltaic cell U m is used as the reference value of the photovoltaic side port voltage. Through the PI regulator and SPS, the drive signal is controlled and output to the photovoltaic side switch tube, so that the photovoltaic side port voltage is constant at this reference value, enabling the photovoltaic cell array to operate at the maximum power point and transmit power to the Bus 1 bus at the maximum power, thereby improving the energy transmission efficiency of this port; the control objective of this port can be achieved by applying the drive signal to the photovoltaic side switch tube; 3) The rSOC side port controls the charge and discharge state of the rSOC and the battery current I rSOC , after determining the charge and discharge working state of the rSOC, a suitable rSOC current reference value can be given, and then I can be achieved through PI regulator and SPS control rSOC constant to this reference value, establish the partial power conversion structure of this port, and enable the stable operation of the rSOC; the control target of this port can be achieved by giving the drive signal to the switch tube on the rSOC side.

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