Bidirectional soft-switching DC converter topology based on heterogeneous main and auxiliary branch integration and its operation method

Abstract

The present invention discloses a bidirectional soft-switching DC converter topology based on heterogeneous main and auxiliary branch integration and an operating method thereof. The topology comprises: a primary main power branch, a primary auxiliary power branch, a transformer group and a secondary H5 inverter; the primary main power branch comprises a Si IGBT and containing an anti-parallel diode connected in series, the primary auxiliary power branch comprises a MOSFET and connected in series, the transformer group comprises a main power transformer and an auxiliary power transformer; the secondary H5 inverter comprises a Si IGBT containing an anti-parallel diode, and the operating method comprises an energy forward flow mode and an energy reverse transmission mode.

Description

Technical Field

[0001] The present invention relates to the technical field of power electronic conversion, and in particular to a bidirectional soft-switching DC converter topology based on heterogeneous main and auxiliary branch integration and an operation method thereof. Background Art

[0002] With the widespread access of distributed photovoltaic power generation, electric vehicles and other DC sources and loads in the distribution network, the existing AC distribution network is evolving towards an AC / DC hybrid distribution network. As the bearer of electrical isolation and DC voltage conversion functions, the isolated bidirectional DC / DC converter (IBDC) plays a vital role in the AC / DC hybrid distribution network and is also one of the focuses of research on the AC / DC hybrid distribution network.

[0003] Traditional single-phase-shifted IBDC has the problems of large reflux power and loss of soft switching under light load, making it difficult to achieve efficient operation within the full load range. In order to reduce the reflux power during IBDC operation and expand the soft switching operation range of IBDC, methods such as extended phase-shift control, double phase-shift control, triple phase-shift control, and hybrid multiple control have been proposed. However, the above-mentioned optimization control strategies cannot completely eliminate the reflux power and soft switching within the full load range, and the converter has many modes and the analysis process is complicated.

[0004] In order to achieve soft switching of the converter and eliminate the backflow power in the full load range, the existing power electronic transformers mostly use resonant IBDC as a unit to build the intermediate stage. However, in order to achieve ZVS of the switch tube, the resonant IBDC usually needs to connect capacitors in parallel at both ends of each switch tube or use SiC MOSFET with large parasitic capacitance and high switching speed. In addition, there are many resonant cavity energy storage elements, the device cost is high and the parameter design is difficult. Summary of the invention

[0005] In view of this, the present invention provides a bidirectional soft-switching DC converter topology based on heterogeneous main and auxiliary branch integration and an operating method thereof, so as to at least solve the problem that the converter control strategy in the prior art is difficult to achieve efficient operation within the full load range and has high performance requirements and high cost for MOSFET.

[0006] In order to achieve the above object, the present invention adopts the following technical solution:

[0007] A bidirectional soft-switching DC converter topology based on heterogeneous main and auxiliary branch integration, including: a primary main power branch, a primary auxiliary power branch, a transformer group and a secondary H5 inverter;

[0008] Input voltage The positive and negative electrodes are connected to the input capacitor and , input capacitance and They are respectively connected to the primary main power branches;

[0009] The primary main power branch includes a series-connected anti-parallel diode and The primary auxiliary power branch includes a series and , the transformer group includes the main power transformer and auxiliary power transformer ;

[0010] in and The series nodes are denoted as Point, input capacitance and The connected nodes are denoted by point, Point through the transmission inductor and The original edges are connected, Point and The original edges are directly connected. and Both The original edges are connected, and The secondary side is connected to the secondary side H5 inverter;

[0011] Secondary side Inverter including IGBT and its corresponding anti-parallel diode ,in The emitter and The collector junction of The secondary side of the same name, Emitter and The collector junction is connected to The secondary side synonym, The collector and The collectors of The collector of The emitter and The emitter of the output capacitor The negative pole is connected to The emitter and output side capacitance The positive pole is connected to The positive electrode is connected to The emitter of The collector, The positive electrode is connected to The emitter of The collector, The positive electrode is connected to The emitter of The collector, The positive electrode is connected to The emitter of The collector, The positive electrode is connected to The emitter of The collector.

[0012] Preferably, the input voltage The positive and negative electrodes are connected to the input capacitors and ,in The positive electrode and The collectors are connected to the input voltage The positive electrode, The negative electrode and The emitters are connected to the input voltage The negative electrode, The negative electrode and The positive terminal is connected to the The original side of the antonym end;

[0013] The primary side of the same name and the transmission inductor One end is connected, The same-name end of the original edge The other end of is connected to the The emitter and The collector junction of The source and The node connected to the drain of The original side of the antonym end; The secondary side synonymous end and The secondary side of is connected to the same-name end.

[0014] A bidirectional soft-switching DC converter topology operation method based on heterogeneous main and auxiliary branch integration includes: an energy forward flow mode and an energy reverse transmission mode;

[0015] In the energy forward transfer mode, the first half cycle and the second half cycle and Alternating conduction, Keep conducting. Keep the shutdown state, the secondary current flow path is The anti-parallel diode and constitute;

[0016] The first half of the cycle is divided into and Three time periods; the second half of the cycle is symmetrical with the first half of the cycle;

[0017] During the time period Keep off, the inductor current go through and , current go through and ;and The voltage across the two ends is greater than 0, and the inductor current gradually increases; time, for Conductivity, for Shut down; Voltage between nodes , The primary voltage is , The secondary voltage is ,in for The ratio of the secondary winding turns to the primary winding turns;

[0018] During the time period, time, Shutdown, current for Drain-source capacitance discharge, The drain-source capacitance is charged when When the drain-source capacitance voltage is less than 0 The body diode conducts to carry out freewheeling, and the input current There was a sudden drop due to In current The peak turn-off Drain-source capacitance discharge and The duration of the drain-source capacitor charging process is short and negligible, so the capacitor voltage cannot change suddenly. accomplish Shut down; The voltage across the two ends is less than 0, and the inductor current gradually decreases;

[0019] During the time period, Keep off, time, The body diode, The anti-parallel diode The anti-parallel diode is realized Off, no current flows in the circuit. and Still keep the conduction state; At this moment, the first half of the cycle ends and the second half of the cycle begins. accomplish Shutdown, accomplish Open, accomplish Conductivity;

[0020] In the reverse energy transfer mode, the first half cycle and the second half cycle and Alternating conduction, The main body remains in the off state, and the switch tube and And the switch pair and The secondary current flow path is composed of the first half cycle and the second half cycle. Ontology and The anti-parallel diodes are formed;

[0021] The first half of the cycle is divided into , and Three time periods;

[0022] During the time period, time, , for Conductivity, for Shut down; go through The anti-parallel diode , and , current go through The anti-parallel diode and , Voltage between nodes , The primary voltage is 0, the voltage across the inductor is less than 0, and the inductor current increases in the opposite direction;

[0023] During the time period, time, accomplish Shutdown, current for Drain-source capacitance charging, The drain-source capacitance is discharged when When the voltage of the capacitor between the drain and source is less than 0, its body diode is turned on for freewheeling. The anti-parallel diode is turned on; go through Anti-parallel diode, and , current go through Anti-parallel diode, The body diode and The primary input voltage is , the voltage across the inductor is greater than 0, and the inductor current decreases in the opposite direction;

[0024] During the time period, time, The body diode and Body diode implementation Shutdown, The anti-parallel diode is turned off, and no current flows in the circuit. and Still keep conducting, At this moment, the first half of the cycle ends and the second half of the cycle begins. accomplish Shutdown, accomplish Open, accomplish Conductivity;

[0025] The second half of the cycle is divided into , and Three time periods, as well as The switch and the first half cycle , and The three time periods are symmetrical; At this moment, the current flows from Transfer to The body diode, There was a sudden increase.

[0026] Preferably, in the energy forward transfer mode During the time period:

[0027] Voltage across the inductor for:

[0028] (1)

[0029] in, for The ratio of the secondary winding turns to the primary winding turns, is the DC voltage at the input side, is the DC voltage at the output side;

[0030] The expression is:

[0031] (2)

[0032] Output Current The expression is:

[0033] (3)

[0034] Input current The expression is:

[0035] (4).

[0036] Preferably, in the energy forward transfer mode During the time period:

[0037] The primary input voltage is 0, so the inductor The voltage across the terminals is:

[0038] (5)

[0039] Therefore The expression is:

[0040] (6)

[0041] Output Current and current With the energy forward transfer mode During the time period and The calculation method remains consistent.

[0042] Preferably, in the energy reverse transfer mode During the time period:

[0043] The voltage across the inductor and the energy forward transfer mode The calculation method of the voltage across the inductor in the time period remains the same. The expression is:

[0044] (7)

[0045] Output Current and current With the energy forward transfer mode Within the time period and The calculation method remains consistent.

[0046] Preferably, in the energy reverse transfer mode During the time period:

[0047] The voltage across the inductor and the energy forward transfer mode The calculation method of the voltage across the inductor remains consistent within the time period;

[0048] The expression is:

[0049] (8)

[0050] Current With the energy forward transfer mode Within the time period The calculation method remains consistent.

[0051] It can be seen from the above technical solutions that, compared with the prior art, the present invention discloses a bidirectional soft-switching DC converter topology based on heterogeneous main and auxiliary branch integration and an operation method thereof, which has the following beneficial effects:

[0052] The present invention can effectively realize the soft switching of all switch tubes, and adopts Si IGBT at the ZCS switch and SiC MOSFET at the ZVS switch, which completely eliminates the switching loss during the operation of the converter and maximizes the operation efficiency of the converter; and by adopting the H5 inverter structure at the output side bridge arm, the converter has the ability of bidirectional energy transmission. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0054] Figure 1 A schematic diagram of the topological structure of a bidirectional soft-switching DC converter based on heterogeneous main and auxiliary branch integration provided by the present invention;

[0055] Figure 2 A waveform diagram of energy forward transmission in a topology operation method of a bidirectional soft-switching DC converter based on heterogeneous main and auxiliary branch integration provided by the present invention;

[0056] Figure 3A schematic diagram of the working state in the energy forward flow mode in the bidirectional soft-switching DC converter topology operation method based on heterogeneous main and auxiliary branch integration provided by the present invention, wherein Figure 3 (a) Working state in the time period energy forward flow mode, Figure 3 (b) Working state in the time period energy forward flow mode, Figure 3 (c) Working status in the time period energy forward flow mode;

[0057] Figure 4 A waveform diagram of energy reverse transmission in a topology operation method of a bidirectional soft-switching DC converter based on heterogeneous main and auxiliary branch integration provided by the present invention;

[0058] Figure 5 A schematic diagram of the working state in the energy reverse flow mode in the bidirectional soft-switching DC converter topology operation method based on heterogeneous main and auxiliary branch integration provided by the present invention, wherein Figure 5 (a) Working status in the energy reverse flow mode during the time period, Figure 5 (b) Working status in the energy reverse flow mode during the time period, Figure 5 (c) Working status in the energy reverse flow mode during the time period;

[0059] Figure 6 This is a simulation waveform diagram under the energy forward flow mode provided by an embodiment of the present invention, wherein: Figure 6 (a) is the output voltage Waveform, Figure 6 (b) is the inductor current Waveform, Figure 6 (c) Transformer Input Current Waveform;

[0060] Figure 7 The device voltage and current waveform diagram under the energy forward flow mode provided by the embodiment of the present invention, wherein: Figure 7 (a) is the switch tube The voltage and current waveforms between collector and emitter; Figure 7 (b) is the switch tube Voltage and current waveforms between drain and source; Figure 7 (c) is the switch tube Voltage and current across an anti-parallel diode;

[0061] Figure 8 This is a simulation waveform diagram under the energy reverse flow mode provided by an embodiment of the present invention, wherein: Figure 8 (a) is the input voltage Waveform, Figure 8 (b) is the inductor current Waveform, Figure 8 (c) Transformer Input Current Waveform;

[0062] Fig. 9 The device voltage and current waveform diagram under the energy reverse flow mode provided by the embodiment of the present invention, wherein: Fig. 9 (a) is the switch tube The voltage and current waveforms between collector and emitter; Fig. 9 (b) is the switch tube Voltage and current waveforms between drain and source; Fig. 9 (c) is the switch tube The voltage and current between collector and emitter;

[0063] Fig.10 A load dump waveform diagram in a forward energy flow mode provided by an embodiment of the present invention;

[0064] Fig.11 A load dump waveform diagram in an energy reverse flow mode provided by an embodiment of the present invention;

[0065] Fig.12 The current waveform diagram when the energy flow direction suddenly changes is provided in the embodiment of the present invention, wherein: Fig.12 (a) is the complete current waveform when the energy flow direction suddenly changes; Fig.12 (b) is the enlarged waveform of the energy sudden change at 1s; Fig.12 (c) is the enlarged waveform of the energy sudden change at 1.1s; Fig.12 (d) The enlarged waveform of the sudden change in energy at 1.2s. Fig.12 (e) Enlarged waveform of the energy sudden change at 1.4s. DETAILED DESCRIPTION

[0066] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0067] On the basis of traditional IBDC, in order to further achieve comprehensive optimization of device efficiency, power density and cost, the present invention provides a bidirectional soft-switching DC converter topology based on heterogeneous main and auxiliary branch integration, that is, the main and auxiliary power split IBDC topology (Main and Auxiliary Power Split IBDC, MAPSI) structure of the H5 inverter, such as Figure 1 As shown, it includes: a primary side main power branch, a primary side auxiliary power branch, a transformer group and a secondary side H5 inverter;

[0068] Input voltage The positive and negative electrodes are connected to the input capacitor and , input capacitance and They are respectively connected to the primary main power branches;

[0069] The primary main power branch includes a series anti-parallel diode and The primary auxiliary power branch includes a series and , the transformer group includes the main power transformer and auxiliary power transformer In this embodiment, the IGBT adopts Si IGBT and the MOSFET adopts SiC MOSFET.

[0070] in and The series nodes are denoted as Point, input capacitance and The connected nodes are denoted by point, Point through the transmission inductor and The original edges are connected, Point and The original edges are directly connected. and Both The original edges are connected, and The secondary side is connected to the secondary side H5 inverter;

[0071] Secondary side Inverter including IGBT and its corresponding anti-parallel diode ,in The emitter and The collector junction of The secondary side of the same name, Emitter and The collector junction is connected to The secondary side synonym, The collector and The collectors of The collector of The emitter and The emitter of the output capacitor The negative pole is connected to The emitter and output side capacitance The positive pole is connected to The positive electrode is connected to The emitter of The collector, The positive electrode is connected to The emitter of The collector, The positive electrode is connected to The emitter of The collector, The positive electrode is connected to The emitter of The collector, The positive electrode is connected to The emitter of The collector.

[0072] In order to further implement the above technical solution, the input voltage The positive and negative electrodes are connected to the input capacitors and ,in The positive electrode and The collectors are connected to the input voltage The positive electrode, The negative electrode and The emitters are connected to the input voltage The negative electrode, The negative electrode and The positive terminal is connected to the The original side of the antonym end;

[0073] The primary side of the same name and the transmission inductor One end is connected, The same-name end of the original edge The other end of is connected to the The emitter and The collector junction of The source and The node connected to the drain of The original side of the antonym end; The secondary side synonymous end and The secondary side of is connected to the same-name end.

[0074] A bidirectional soft-switching DC converter topology operation method based on heterogeneous main and auxiliary branch integration includes: an energy forward flow mode and an energy reverse transmission mode;

[0075] When the energy flows in the forward direction, the main working waveform of MAPSI is as follows: Figure 2 In the forward energy transfer mode, the first half cycle and the second half cycle and Alternating conduction, Keep conducting. Keep the shutdown state, the secondary current flow path is The anti-parallel diode and constitute;

[0076] Due to the symmetry of the MAPSI operating state, in this embodiment, only the operating state of the first half cycle is analyzed. The current paths of each operating state are as follows: Figure 3 The first half cycle is divided into , and Three time periods; the second half of the cycle is symmetrical with the first half of the cycle;

[0077] During the time period, is the starting point of each switching cycle. time, , Conductivity, Shutdown. Before time , the current in the circuit is 0, so for Conductivity, for Shut down.

[0078] The current path in this state is Figure 3 (a) shows the current go through flow, current go through In this state, Voltage between nodes , The primary voltage is , so its secondary voltage is .

[0079] Voltage across the inductor for:

[0080] (1)

[0081] in, for The ratio of the secondary winding turns to the primary winding turns, is the DC voltage at the input side, is the DC voltage at the output side;

[0082] Therefore, the current The expression is:

[0083] (2)

[0084] Output Current The expression is:

[0085] (3)

[0086] Input current The expression is:

[0087] (4)

[0088] In order to achieve the purpose of forward energy flow, the voltage across the inductor should be greater than 0 in this state, and the inductor current gradually increases.

[0089] During the time period, Moment, switch tube Shutdown, current for Drain-source capacitance discharge, The drain-source capacitance is charged when When the drain-source capacitor voltage is less than 0, its body diode conducts and continues to flow, so the input current at this moment is There will be a sudden drop. In current The peak turn-off Drain-source capacitance discharge and The duration of the drain-source capacitor charging process is very short and can be ignored here. It can be achieved Si IGBT has tail current effect, so the turn-off time is long. In order to reduce the capacitance value connected in parallel at both ends of the device, Replace with SiC MOSFETs which have higher turn-off speed and larger parasitic capacitance.

[0090] The current path in state 2 is as follows Figure 3 (b) shows the current go through flow, current go through The body diode is conducting. The primary input voltage is 0, so the inductor The voltage across the terminals is:

[0091] (5)

[0092] Therefore, the current The expression is:

[0093] (6)

[0094] Output Current The expression of current is shown in formula (3). The expression of is shown in equation (4). In order to achieve critical continuity or discontinuity of the inductor current, the voltage across the inductor should be less than 0 in this state, and the inductor current gradually decreases.

[0095] During the time period, At this moment, the inductor current drops to 0. Body diode, Anti-parallel diode, The anti-parallel diode realizes In this state, no current flows through the circuit. , Still remain in the on state. At this moment, the first half of the cycle ends and the second half of the cycle begins. Shutdown, , Since Before time t, the current in the circuit is 0 and The voltage across the two ends is 0, so Achieved Shutdown, Achieved Open, Achieved Conductivity.

[0096] In the reverse energy transfer mode, the first half cycle and the second half cycle and Alternating conduction, The main body remains in the off state, and the switch tube and And the switch pair and The secondary current flow path is composed of the first half cycle and the second half cycle. Ontology and The anti-parallel diodes are formed;

[0097] Due to the symmetry of the MAPSI operating state, this embodiment still only analyzes the operating state of the first half cycle. The current paths of each operating state are as follows: Figure 5 In this mode, the reference directions of each current are as follows: Figure 5 The first half cycle is divided into , and Three time periods;

[0098] During the time period, is the starting point of each switching cycle. time, Conductivity, Shutdown. Before time , the current in the circuit is 0, so for Conductivity, for Shut down.

[0099] The current path in this state is Figure 5 (a) shows the current go through Anti-parallel diode, flow, current go through Anti-parallel diode, In this state, Voltage between nodes , The primary voltage is 0, so the voltage across the inductor is as shown in equation (5). The expression is:

[0100] (7)

[0101] Output Current The expression of current is shown in formula (3). The expression of is shown in formula (4). In order to achieve the purpose of reverse energy flow, the voltage across the inductor should be less than 0 in this state, and the inductor current increases in the reverse direction.

[0102] During the time period, Moment, switch tube Shutdown, current for Drain-source capacitance charging, The drain-source capacitance is discharged when When the drain-source capacitor voltage is less than 0, its body diode conducts and continues to flow, so the input current at this moment There will be a sudden increase. In current The peak value of the switch is turned off. The above charging and discharging process lasts for a very short time and can be ignored here. It can be achieved .

[0103] The current path in state 2 is as follows Figure 5 (b) shows the current go through Anti-parallel diode, , , flow, current go through Anti-parallel diode, Body diode, Circulation. The primary input voltage is , so the inductance The voltage across the two terminals is shown in equation (1).

[0104] Current The expression is:

[0105] (8)

[0106] Current The expression of is shown in formula (4).

[0107] In order to achieve critical continuity or discontinuity of the inductor current, the voltage across the inductor should be greater than 0 in this state, and the inductor current decreases in the opposite direction.

[0108] During this time period, the current path is as follows Figure 5 (c) shows that At this moment, the inductor current Increase to 0, Body diode, The body diode realizes Shutdown. The unidirectional conduction characteristics of the anti-parallel diode, the inductor current It cannot continue to increase in the positive direction, so no current flows in the circuit in this state. Still remain in the on state. At this moment, the first half of the cycle ends and the second half of the cycle begins. Shutdown, Since Before time t, the current in the circuit is 0 and The voltage across the two ends is 0, so Achieved Shutdown, Achieved Open, Achieved Conductivity.

[0109] In addition, moment, since the current will flow from Transfer to The body diode, so the input current There will be a sudden increase.

[0110] In summary, in the two operating modes, All can be achieved . Achievable Conductivity, In the forward energy flow mode, It remains on all the time, and no current flows through its anti-parallel diode; in the energy reverse flow mode, Always keep off, its anti-parallel diode can achieve .

[0111] In order to better prove the effectiveness of the topology and modulation method proposed in the present invention, the following simulation examples are used for verification. Figure 1 The HDH-DAB topology shown in the figure is used to build a simulation platform in MATLAB / Simulink. The simulation parameters are shown in Table 1.

[0112] ;

[0113] Energy forward transfer simulation results:

[0114] Figure 6 It is the MAPSI simulation waveform when the energy flows in the forward direction. Figure 6 (a) is the output voltage Waveform, Figure 6 (b) is the inductor current Waveform, Figure 6 (c) Transformer Input Current Waveform. Figure 6 (a) It can be seen that the output voltage It fluctuates around the reference value of 750V, with a fluctuation range of about 30V. Figure 6 (b) with Figure 6 (c) The circuit is in a discontinuous state, which verifies the correctness of the theoretical analysis. Due to the voltage fluctuation between the input side capacitor and the output side capacitor, the voltage across the inductor fluctuates. Therefore, It does not change strictly according to the linear law. In addition, due to The power transmitted is much smaller than ,and The input voltage amplitude is twice as much, The magnitude is much smaller than .

[0115] Figure 7 The voltage and current waveforms of the two ends of each switch tube of MAPSI in the energy forward flow mode are shown. Figure 7 (a) is the switch tube The voltage and current waveforms between collector and emitter; Figure 7 (b) is the switch tube Voltage and current waveforms between drain and source; Figure 7 (c) is the switch tube Voltage and current across an anti-parallel diode.

[0116] from Figure 7 (a) It can be seen that the switch tube The current is 0 before turning on and off, so the switch tube Achieved On, off. Figure 7 (b) In Before the body diode is turned on, its drain-source capacitance is discharged to a voltage of 0. After the body diode is turned on, a reverse current flows through it, and it is naturally turned off after the current increases to 0. The voltage between the drain and source is always kept at 0, so When the trigger signal is forward-conducting, it can be realized When turned off, the capacitor voltage cannot change suddenly. It can achieve Shut down. Figure 7 (c) In Before the anti-parallel diode is turned on and off, the current in the circuit is 0 and there is no switching loss.

[0117] Energy reverse transfer simulation results:

[0118] Figure 8 It is the MAPSI simulation waveform when the energy flows in the reverse direction. Figure 8 (a) is the input voltage Waveform, Figure 8 (b) is the inductor current Waveform, Figure 8 (c) Transformer Input Current Waveform. Figure 8 (a) It can be seen that the input voltage It fluctuates around the reference value of 2000V, with a fluctuation range of about 12V. Figure 8 (b) with Figure 8 (c) It is in a discontinuous state, and its phase is opposite to that when the energy flows forward, which is consistent with the theoretical analysis.

[0119] Fig. 9 The voltage and current waveforms of each switch tube of MAPSI under the reverse energy flow mode are shown. Fig. 9 (a) is the switch tube The voltage and current waveforms between collector and emitter; Fig. 9 (b) is the switch tube Voltage and current waveforms between drain and source; Fig. 9 (c) is the switch tube The voltage and current between the collector and emitter. Fig. 9 (a) It can be seen that the switch tube The current is 0 before turning on and off, so the switch tube Achieved On, off. Fig. 9 (b) In Before the body diode is turned on, its drain-source capacitance is discharged to a voltage of 0. After the body diode is turned on, a reverse current flows through it, and it is naturally turned off after the current increases to 0. After the body diode is turned on, The voltage between the drain and source is always kept at 0, so When the trigger signal is forward-conducting, it can be realized When turned off, the capacitor voltage cannot change suddenly. It can be achieved Shut down. Fig. 9 (c) In Before turning on and off, the current in the circuit is 0, so the switch tube Achieved On, off.

[0120] Transient process simulation analysis:

[0121] Fig.10 Shows the inductor current during load dump in forward energy flow mode The waveform is shown in Figure 1. 0.7s ago, the transmission power was 200kW. 0.7s later, the load dropped to 50% of the rated power, i.e., 100kW. Fig.10 It can be seen that during load dump, It is still possible to maintain intermittent operation and soft switching of each switch tube in the converter can still be achieved.

[0122] Fig.11 Shows the inductor current during load dump in reverse energy flow mode The waveform is shown in Figure 1.5. Before 1.5 seconds, the transmission power is 200kW. After 1.5 seconds, the load drops to 50% of the rated power, i.e. 100kW. Fig.11 It can be seen that during load dump, It is still possible to maintain intermittent operation and soft switching of each switch tube in the converter can still be achieved.

[0123] Inductor current when MAPSI energy flow direction changes suddenly Waveform Fig.12 As shown. To ensure the soft switching of the switch tube, the energy first changes from 200kW in the forward direction to 40kW in the reverse direction at 1s, then changes to 80kW in the reverse direction at 1.1s, 160kW in the reverse direction at 1.2s, and finally changes to 200kW in the reverse direction at 1.4s. It can be seen that since the amplitude of each energy mutation is small, it will not have a significant impact on the capacitor voltage, so the inductor current can maintain critical continuity or discontinuity, ensuring the soft switching of the device.

[0124] Converter loss analysis:

[0125] In order to measure the efficiency of MAPSI, a device loss measurement model was built in PLECS. Adopt FF450R33T3E3 (3300V / 450A), Adopt C2M0045170P (1700V / 48A) double tubes in series, Adopt FS450R12OE4P (1200V / 450A). It can be achieved Open and When turned off, the series devices do not need to be dynamically balanced, and the impact on the device loss and reliability is very small. When the ambient temperature is 100°C, the device loss and efficiency of the device under different loads are shown in Tables 2 and 3. Since all switching tubes can achieve soft switching, the switching loss of the converter is 0. Unlike the traditional single-phase control DAB, the MAPSI of the present invention will not lose the soft switch under light load, so its efficiency will not decrease. It can be seen from Tables 2 and 3 that MAPSI can achieve an operating efficiency of more than 99.3% within the full load range.

[0126] ;

[0127] ;

[0128] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. A bidirectional soft-switching DC converter topology based on heterogeneous main and auxiliary branch integration, characterized in that: include: Primary side main power branch, primary side auxiliary power branch, transformer group and secondary side H5 inverter; Input voltage The positive and negative electrodes are connected to the input capacitor and , input capacitance and They are respectively connected to the primary main power branches; The primary main power branch includes IGBTs in series with anti-parallel diodes. and The primary auxiliary power branch includes a series MOSFET and , the transformer group includes the main power transformer and auxiliary power transformer ; in and The series nodes are denoted as Point, input capacitance and The connected nodes are denoted by point, Point through the transmission inductor and The original edges are connected, Point and The original edges are directly connected. and Both The original edges are connected, and The secondary side is connected to the secondary side H5 inverter; Secondary side Inverter including IGBT and its corresponding anti-parallel diode ,in The emitter and The collector junction of The secondary side of the same name, Emitter and The collector junction is connected to The secondary side synonym, The collector and The collectors of The collector of The emitter and The emitter of the output capacitor The negative pole is connected to The emitter and output side capacitance The positive pole is connected to The positive electrode is connected to The emitter of The collector, The positive electrode is connected to The emitter of The collector, The positive electrode is connected to The emitter of The collector, The positive electrode is connected to The emitter of The collector, The positive electrode is connected to The emitter of The collector.

2. The bidirectional soft-switching DC converter topology based on heterogeneous main and auxiliary branch integration according to claim 1 is characterized in that: Input voltage The positive and negative electrodes are connected to the input capacitors and ,in The positive electrode and The collectors are connected to the input voltage The positive electrode, The negative electrode and The emitters are connected to the input voltage The negative electrode, The negative electrode and The positive terminal is connected to the The original side of the antonym end; The primary side of the same name and the transmission inductor One end is connected, The same-name end of the original edge The other end of is connected to the The emitter and The collector junction of The source and The node connected to the drain of The original side of the antonym end; The secondary side synonymous end and The secondary side of is connected to the same-name end.

3. A bidirectional soft-switching DC converter topology operation method based on heterogeneous main and auxiliary branch integration, based on the bidirectional soft-switching DC converter topology based on heterogeneous main and auxiliary branch integration according to any one of claims 1-2, characterized in that: include: Energy forward flow mode and energy reverse transfer mode; In the energy forward transfer mode, the first half cycle and the second half cycle and Alternating conduction, Keep conducting. Keep the shutdown state, the secondary current flow path is The anti-parallel diode and constitute; The first half of the cycle is divided into and Three time periods; the second half of the cycle is symmetrical with the first half of the cycle; During the time period Keep off, the inductor current go through and , current go through and ;and The voltage across the two ends is greater than 0, and the inductor current gradually increases; time, for Conductivity, for Shut down; Voltage between nodes , The primary voltage is , The secondary voltage is ,in for The ratio of the secondary winding turns to the primary winding turns; During the time period, time, Shutdown, current for Drain-source capacitance discharge, The drain-source capacitance is charged when When the drain-source capacitance voltage is less than 0 The body diode conducts to carry out freewheeling, and the input current There was a sudden drop due to In current The peak turn-off Drain-source capacitance discharge and The duration of the drain-source capacitor charging process is short and negligible, so the capacitor voltage cannot change suddenly. accomplish Shut down; The voltage across the two ends is less than 0, and the inductor current gradually decreases; During the time period, Keep off, time, The body diode, The anti-parallel diode The anti-parallel diode is realized Off, no current flows in the circuit. and Still keep the conduction state; At this moment, the first half of the cycle ends and the second half of the cycle begins. accomplish Shutdown, accomplish Open, accomplish Conductivity; In the reverse energy transfer mode, the first half cycle and the second half cycle and Alternating conduction, The main body remains in the off state, and the switch tube and And the switch pair and The secondary current flow path is composed of the first half cycle and the second half cycle. Ontology and The anti-parallel diodes are formed; The first half of the cycle is divided into , and Three time periods; During the time period, time, , for Conductivity, for Shut down; go through The anti-parallel diode and , current go through The anti-parallel diode and , Voltage between nodes , The primary voltage is 0, the voltage across the inductor is less than 0, and the inductor current increases in the opposite direction; During the time period, time, accomplish Shutdown, current for Drain-source capacitance charging, The drain-source capacitance is discharged when When the voltage between the drain-source capacitor is less than 0, its body diode is turned on for freewheeling. The anti-parallel diode is turned on; go through Anti-parallel diode, and , current go through Anti-parallel diode, The body diode and , The primary input voltage is , the voltage across the inductor is greater than 0, and the inductor current decreases in the opposite direction; During the time period, time, The body diode and Body diode implementation Shutdown, The anti-parallel diode is turned off, and no current flows in the circuit. , and Still keep conducting, At this moment, the first half of the cycle ends and the second half of the cycle begins. accomplish Shutdown, accomplish Open, accomplish Conductivity; The second half of the cycle is divided into and Three time periods, as well as The switch and the first half cycle and The three time periods are symmetrical; At this moment, the current flows from Transfer to The body diode, There was a sudden increase.

4. The bidirectional soft-switching DC converter topology operation method based on heterogeneous main and auxiliary branch integration according to claim 3 is characterized in that: In the forward energy transfer mode During the time period: Voltage across the inductor for: (1) in, for The ratio of the secondary winding turns to the primary winding turns, is the DC voltage at the input side, is the DC voltage at the output side; The expression is: (2) Output Current The expression is: (3) Input current The expression is: (4)。 5. The bidirectional soft-switching DC converter topology operation method based on heterogeneous main and auxiliary branch integration according to claim 3 is characterized in that: In the forward energy transfer mode During the time period: The primary input voltage is 0, so the inductor The voltage across the terminals is: (5) Therefore The expression is: (6) Output Current and current With the energy forward transfer mode During the time period and The calculation method remains consistent.

6. The bidirectional soft-switching DC converter topology operation method based on heterogeneous main and auxiliary branch integration according to claim 3 is characterized in that: In the reverse energy transfer mode During the time period: The voltage across the inductor and the energy forward transfer mode The calculation method of the voltage across the inductor in the time period remains the same. The expression is: (7) Output Current and current With the energy forward transfer mode Within the time period and The calculation method remains consistent.

7. The bidirectional soft-switching DC converter topology operation method based on heterogeneous main and auxiliary branch integration according to claim 3 is characterized in that: In the reverse energy transfer mode During the time period: The voltage across the inductor and the energy forward transfer mode The calculation method of the voltage across the inductor remains consistent within the time period; The expression is: (8) Current With the energy forward transfer mode Within the time period The calculation method remains consistent.

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