Universe soft-switching heterogeneous direct-current converter adaptive to bidirectional power requirement and operation method of universe soft-switching heterogeneous direct-current converter

Abstract

The invention discloses a global soft switching heterogeneous direct current converter adaptive to bidirectional power requirements and an operation method thereof. The converter comprises an input side main power branch, an input side auxiliary power branch, a transformer bank, an output side reverse power full bridge and an output side forward power full bridge, the operation method comprises an energy forward transmission 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 global soft-switching heterogeneous DC converter adapted to bidirectional power requirements and an operating method thereof. Background Art

[0002] As the proportion of DC sources and loads such as photovoltaic power generation, electric vehicles, and air conditioners in the power grid continues to increase, AC / DC hybrid distribution networks will become a new form of distribution networks in the future. At present, a small number of DC distribution parks with distributed photovoltaic power generation have been demonstrated in AC distribution networks. As a device that connects DC buses of different voltage levels in AC / DC hybrid distribution networks, isolated bidirectional DC transformers (IBDC) play a core role in AC / DC hybrid distribution networks.

[0003] In order to achieve low-carbon operation of the power system, existing distributed photovoltaic power generation parks all adopt strategies such as energy storage and electricity price optimization to maximize the consumption rate of new energy. When the distributed photovoltaic power generation is at its peak, its power is first supplied to the park load and energy storage, and the excess power is fed into the upper DC bus; when the distributed photovoltaic power generation is at its valley state, the power required by the load needs to be obtained from the upper DC bus. Therefore, the low-voltage DC bus usually obtains power from the high-voltage level, and only feeds a small amount of energy to the high-voltage DC bus in a small period of time.

[0004] Therefore, if the forward and reverse power paths on the low-voltage side of the IBDC can be reshaped, a large-capacity uncontrolled rectifier bridge can be used for the forward power path with larger current, and a small-capacity unidirectional inverter structure can be used for the reverse power path with smaller current. This will achieve the goal of reducing the cost of using IBDC in existing urban DC distribution parks.

[0005] The most commonly used IBDC topology is the Dual Active Bridge (DAB), which has a simple structure and high efficiency. However, DAB still has the following defects: First, when the load is light and the input and output voltages do not match, DAB will lose the ability to open the zero voltage switch over a large range, resulting in a significant reduction in the efficiency of the device; second, it is difficult to achieve soft shutdown of the switch tube using traditional phase-shift modulation DAB; finally, the input and output sides of DAB use reverse-conducting active devices to construct the H-bridge, resulting in coupling of the forward and reverse power paths. In scenarios where the forward and reverse transmission power is very different, such as urban DC distribution parks, the reverse path capacity is difficult to be fully utilized. Summary of the invention

[0006] In view of this, the present invention provides a global soft-switching heterogeneous DC converter that is adaptable to bidirectional power requirements and an operating method thereof, so as to at least solve the problem in the prior art that the reverse path capacity of the traditional IBDC transformer is difficult to be fully utilized in scenarios where the forward and reverse transmission power differ greatly.

[0007] In order to achieve the above object, the present invention adopts the following technical solution: A global soft-switching heterogeneous DC converter adapted to bidirectional power requirements, comprising: an input side main power branch, an input side auxiliary power branch, a transformer group, an output side reverse power full bridge and an output side forward power full bridge; Input voltage The positive and negative electrodes are connected to the input capacitor C 1 and C 2. Input Capacitance C 1 and C 2 are respectively connected to the main power branches on the input side; The main power branch on the input side includes IGBTs in series with anti-parallel diodes. Q 1 and Q 2. The input side auxiliary power branch includes a series MOSFET Q 3 and Q 4. Transformer group includes main power transformer T r1 and auxiliary power transformer T r2 ; Q 1 and Q 2 Series nodes through the transmission inductor L and T r1 The primary side is connected to the input capacitor C 1 and C 2 connected nodes and T r1 The original edges are directly connected. Q 3 and Q 4 and T r2 The original edges of are connected; The output side reverse power full bridge includes reverse resistance IGBT S 1~ S 4, among which S 1's emitter and S 2's collector is connected, S 3's emitter and S 4's collector is connected, S 1 collector and S The collectors of 3 are connected to the output capacitor C o The positive electrode, S2 emitter and S The emitters of 4 are connected to the output capacitor C o The negative electrode; The output side forward power full bridge includes diodes D 1~ D 4 and IGBT S 5. D 1 anode and D 2's cathodes are connected, D 3 anode and D 4's cathode is connected, D 1 and D The cathode of 3 is S 5's collector is connected, S The emitter of 5 is connected to C o The positive electrode, D 2 and D The anodes of 4 are C o The negative pole is connected; S 1's emitter and S 2 collectors form a node and D 1 anode and D 2 cathode nodes are formed with T r1 The secondary side is connected to the same-named end; S 3's emitter and S 4 forms a node with the collector and D 3 anode and D 4 cathodes form nodes with T r2 The secondary side opposite ends are connected.

[0008] Preferably, C 1's negative electrode and C 2 positive poles are connected, the main power bridge arm Q 1's emitter and Q 2 is connected to the collector of the auxiliary power bridge arm. Q 3 source and Q 4's drain is connected, C 1 are connected to the positive electrode Q 1 collector, Q 3. The drain and input voltage The positive electrode, C 2 are connected to the negative poles Q 2 emitter, Q 4 source and The negative electrode, C 1's negative electrode and C 2 The positive terminal is connected to the nodeT r1 The original side of the antonym end; T r1 The primary side of the same name and the transmission inductor L One end is connected to T r2 The same-name end of the original edge L The other end of is connected to the Q 1's emitter and Q 2's collector junction, Q 3 source and Q The node connected to the drain of 4 is connected to T r2 The original side of the antonym end; T r1 The secondary side synonymous end and T r2 The secondary side of is connected to the same-name end.

[0009] An operating method of a global soft-switching heterogeneous DC converter adapted to bidirectional power requirements, comprising: an energy forward transmission mode and an energy reverse transmission mode; In the forward energy transfer mode, S 1~ S 4 Keep off state, S 5 Keep the conduction state; divide the positive half cycle into [ t 0 , t 1) [ t 1, t 2) and [ t 2, t 3] Three time periods; the negative half cycle and the positive half cycle are symmetrical; [ t 0 , t 1 ) time period, Q 1 and Q 4 conduction, Q 2 and Q 3 off, D 1 and D 4 conduction, D 2 and D 3 shutdown, where t 0 time, Q 1 and Q 4 is ZCS conduction, Q 2. D 2 and D 3 is ZCS shutdown, D 1 and D 4Natural conduction; current i 1 flows throughQ 1. L , T r1 Original edge and C 1, and i 1 is in increasing state, current i 2 flows successively Q 1. T r2 Original edge, Q 4. C 2 and C 1, and i 2 is in increasing state; [ t 1, t 2) During the time period, Q 1 Keep conducting, Q 2 and Q 3 Keep off, Q 4 Shutdown, D 1 and D 4 Keep conducting, D 2 and D 3 remains off, where t 1 moment Q 4 to achieve ZVS shutdown, i 2 for Q The parasitic capacitance of 4 is charged to Q 3 The parasitic capacitance is discharged when Q When the voltage across the parasitic capacitor of 3 is less than 0, Q 3's body diode conducts, i 2 Flow through Q 3 Body diode; current i 1 flows through Q 1. L , T r1 Original edge and C 1, and i 1 is in decreasing state, current i 2 flows successively Q 1. T r2 Original edge and Q 3 body diodes, and i 2 is in decreasing state; [ t 2, t 3] During the time period, Q 1 Keep conducting, Q 2. Q 3 and Q 4 Keep off, D 1. D 2. D 3 and D 4 are all turned off, among which,t 2 Moment, current i 1 and i 2 decays to 0, Q 3 body diode, D 1 and D 4Natural shutdown, Q The voltage across the parasitic capacitor of 3 is 0. Q The voltage across the parasitic capacitor of 4 is , by the output capacitor C o Supply power to the load; t 3 The positive half cycle ends at this moment. Q 1 off, Q 2 and Q 3 conduction, L Limit the rapid rise of current in the converter, the current i 1 and i 2 remains at 0, then Q 1 to achieve ZCS shutdown, Q 2 to achieve ZCS conduction, Q 3. Realize ZVZCS conduction; In the reverse energy transfer mode, S 5 Keep the off state; divide the positive half cycle into [ t 0 , t 1) [ t 1, t 2) and [ t 2, t 3] Three time periods; the negative half cycle and the positive half cycle are symmetrical; [ t 0 , t 1 ) time period, S 1 and S 4 conduction, Q 1 and Q 3 conduction, Q 2 and Q 4 is turned off, and t 0 time Q 1. S 1. S 4 and Q 3 is ZCS conduction, Q 2. S 2 and S 3 is ZCS shutdown; current i 1 Flow Q 1 anti-parallel diode, C 1. T r1 Original edge and L ,andi 1 is in decreasing state, current i 2 Flow Q 1 anti-parallel diode, Q 3 and T r2 The original edge, and i 2 is in decreasing state; [ t 1, t 2) During the time period, S 1 and S 4 Keep conducting, Q 1 Keep conducting, Q 2. Q 3 and Q 4 Shutdown, in t 1 moment, i 2 for Q 3 parasitic capacitance is charged to Q 4 discharges the parasitic capacitance, Q 3 To achieve ZVS shutdown, when Q When the voltage across the parasitic capacitor of 4 is less than 0, Q The body diode of 4 is conducting, i 2 Flow through Q 4 Body diode; current i 1 flows through Q 1 anti-parallel diode, C i1 , T r1 Original edge and L ,and i 1 is in increasing state, current i 2 flows successively Q 1 anti-parallel diode, C i1 , C i2 , Q 4 body diode and T r2 The original edge, and i 1 is in increasing state; [ t 2, t 3] During the time period, S 1 and S 4 Keep conducting, Q 1 Keep conducting, Q 2. Q 3 and Q 4 Shutdown, in t At moment 2, the current in the converter decays to 0. Q The body diode of 4 is naturally turned off, t 2 Moments Q4 The voltage across the parasitic capacitor is 0. Q The voltage across the parasitic capacitor of 3 is Due to the single-phase current-carrying characteristics of the full-bridge on the output side, the current in the converter remains at 0, and the capacitor C 1 and C 2. Supply power to the load; t At moment 3, the positive half cycle ends. Q 1. S 1 and S 4. Achieve ZCS shutdown, Q 2. Q 4. S 2 and S 3. Achieve ZCS conduction.

[0010] Preferably, in the energy forward transfer mode [ t 0 , t 1 ) during the time period: inductance L The voltage across the terminals is: (1) In the formula, V o is the output voltage, N 1 and N 2 are T r1 and T r2 The ratio of the secondary winding turns to the primary winding turns; t is any time within a cycle; The inductor current is: (2) The output current is: (3).

[0011] Preferably, in the energy forward transfer mode [ t 1, t 2) During the time period: The voltage across the inductor is: (4) The inductor current is: (5).

[0012] Preferably, in the energy reverse transfer mode [ t 0 , t 1 ) during the time period: inductance LThe voltage across the terminals is: (6) The inductor current is: (7) Output Current: (8).

[0013] Preferably, in the energy reverse transfer mode [ t 1, t 2) During the time period: The voltage across the inductor is: (9) The inductor current is: (10).

[0014] Preferably, in the energy reverse transmission mode, the first time period in the negative half cycle is ( t 3, t 4], t 4 Moment, current i 2From Q 4Transfer to Q 3 body diodes, i o Appearance and i 2 transitions of equal magnitude.

[0015] It can be seen from the above technical solutions that, compared with the prior art, the present invention discloses a global soft-switching heterogeneous DC converter adapted to bidirectional power requirements and an operating method thereof, which has the following beneficial effects: The present invention can realize 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; by reconstructing the forward and reverse power path structure, the forward power path and the reverse power path are constructed separately, the capacity of the forward and reverse power path devices is decoupled, the forward and reverse power path transmission capacity is customized according to the forward and reverse power transmission requirements, and the forward and reverse power path devices with adapted power transmission capacity are selected, thereby achieving the purpose of reducing the converter cost in the application scenario of forward and reverse power asymmetry. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] 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.

[0017] Figure 1 A schematic diagram of the topological structure of a bidirectional power asymmetric heterogeneous device global soft-switching DC converter BPAHDC provided by the present invention; wherein ① is the main power branch on the input side; ② is the auxiliary power branch on the input side; ③ is the transformer group; ④ is the reverse power full bridge on the output side; ⑤ is the forward power full bridge on the output side; Figure 2 The energy forward transmission waveform diagram of the BPAHDC provided by the present invention; Figure 3 In the energy forward transmission mode of the BPAHDC provided by the present invention, t 0 , t 1) Schematic diagram of the current path during the time period; Figure 4 In the energy forward transmission mode of the BPAHDC provided by the present invention, t 1, t 2) Schematic diagram of the current path during the time period; Figure 5 In the energy forward transmission mode of the BPAHDC provided by the present invention, t 2, t 3] Schematic diagram of the current path during the time period; Figure 6 The energy reverse transmission waveform diagram of the BPAHDC provided by the present invention; Figure 7 The BPAHDC energy reverse transmission waveform diagram provided by the present invention; Figure 8 In the energy reverse transmission mode of the BPAHDC provided by the present invention, t 0 , t 1) Schematic diagram of the current path during the time period; Fig. 9 In the energy reverse transmission mode of the BPAHDC provided by the present invention, t 1, t 2) Schematic diagram of the current path during the time period; Fig.10 In the energy reverse transmission mode of the BPAHDC provided by the present invention, t 2, t 3] Schematic diagram of the current path during the time period; Fig.11 An output voltage waveform diagram under forward energy transmission provided by an embodiment of the present invention; Fig.12 A waveform diagram of the inductor current under forward energy transmission provided by an embodiment of the present invention; Fig.13 The embodiment of the present invention provides Q 1 Voltage and current waveforms; Fig.14 The embodiment of the present invention provides Q 3. Voltage and current waveforms; Fig.15 An output voltage waveform diagram under reverse energy transmission provided by an embodiment of the present invention; Fig.16 A waveform diagram of the inductor current under reverse energy transmission provided by an embodiment of the present invention; Fig.17 The energy reverse transmission provided by the embodiment of the present invention Q 1 Voltage and current waveforms; Fig.18 The energy reverse transmission provided by the embodiment of the present invention Q 3. Voltage and current waveforms; Fig.19 The energy reverse transmission provided by the embodiment of the present invention S 1 Voltage and current waveforms. DETAILED DESCRIPTION

[0018] 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.

[0019] In order to achieve comprehensive optimization of traditional IBDC efficiency, power density and cost, the present invention proposes a bidirectional power asymmetric heterogeneous device global soft-switching DC converter (BPAHDC) topology structure, which decouples the forward and reverse power paths of the secondary side of the traditional IBDC transformer and separately constructs customized forward and reverse power paths according to the forward and reverse power transmission requirements.

[0020] A global soft-switching heterogeneous DC converter adapted to bidirectional power requirements, such as Figure 1As shown, it includes: an input side main power branch, an input side auxiliary power branch, a transformer group, an output side reverse power full bridge and an output side forward power full bridge; Input voltage The positive and negative electrodes are connected to the input capacitor C 1 and C 2. Input Capacitance C 1 and C 2 are respectively connected to the main power branches on the input side; The main power branch on the input side includes IGBTs in series with anti-parallel diodes. Q 1 and Q 2. The input side auxiliary power branch includes a series MOSFET Q 3 and Q 4. Transformer group includes main power transformer T r1 and auxiliary power transformer T r2 ; Q 1 and Q 2 Series nodes through the transmission inductor L and T r1 The primary side is connected to the input capacitor C 1 and C 2 connected nodes and T r1 The original edges are directly connected. Q 3 and Q 4 and T r2 The original edges of are connected; The output side reverse power full bridge includes reverse resistance IGBT S 1~ S 4, among which S 1's emitter and S 2's collector is connected, S 3's emitter and S 4's collector is connected, S 1 collector and S The collectors of 3 are connected to the output capacitor C o The positive electrode, S 2 emitter and S The emitters of 4 are connected to the output capacitor C o The negative electrode; The output side forward power full bridge includes diodes D 1~ D 4 and IGBT S 5. D 1 anode and D2's cathodes are connected, D 3 anode and D 4's cathode is connected, D 1 and D The cathode of 3 is S 5's collector is connected, S The emitter of 5 is connected to C o The positive electrode, D 2 and D The anodes of 4 are C o The negative pole is connected; S 1's emitter and S 2 collectors form a node and D 1 anode and D 2 cathode nodes are formed with T r1 The secondary side is connected to the same-named end; S 3's emitter and S 4 forms a node with the collector and D 3 anode and D 4 cathode nodes are formed with T r2 The secondary side opposite ends are connected.

[0021] It should be noted that: In this embodiment, the input side main power branch is composed of Si IGBT; the input side auxiliary power branch is composed of SiCMOSFET; the output side reverse power full bridge is composed of reverse resistance type Si IGBT; the output side forward power full bridge is composed of diode uncontrolled rectifier full bridge and Si IGBT.

[0022] In order to further implement the above technical solution, C 1's negative electrode and C 2 positive poles are connected, the main power bridge arm Q 1's emitter and Q 2 is connected to the collector of the auxiliary power bridge arm. Q 3 source and Q 4's drain is connected, C 1 are connected to the positive electrode Q 1 collector, Q 3. The drain and input voltage The positive electrode, C 2 are connected to the negative poles Q 2 emitter, Q 4 source and The negative electrode, C 1's negative electrode and C 2 The positive terminal is connected to the Tr1 The original side of the antonym end; T r1 The primary side of the same name and the transmission inductor L One end is connected to T r2 The same-name end of the original edge L The other end of is connected to the Q 1's emitter and Q 2's collector junction, Q 3 source and Q The node connected to the drain of 4 is connected to T r2 The original side of the antonym end; T r1 The secondary side synonymous end and T r2 The secondary side of is connected to the same-name end.

[0023] An operating method of a global soft-switching heterogeneous DC converter adapted to bidirectional power requirements, comprising: an energy forward transmission mode and an energy reverse transmission mode; Energy forward transfer mode: The waveform of BPAHDC in the forward energy transfer state is as follows: Figure 2 When the energy is transferred forward, the secondary side S 1. S 2. S 3. S 4 is always in the off state. S 5 is always in the on state. In half a cycle, BPAHDC is divided into three operating modes, namely: Mode 1[ t 0, t 1]: t 0 is the moment when a cycle starts. Q 1 conduction, Q 2 off, D 1. D 4 conduction, D 2. D 3 shut down. t Before time 0, no current flows through the converter. Q 1. Q 4 is ZCS conduction, Q 2. D 2. D 3 is ZCS shutdown, D 1. D 4Natural conduction.

[0024] In this mode, the inductor L The voltage across the terminals is: (1) In the formula, V o is the output voltage, N 1 and N 2 are T r1 and T r2 The ratio of the secondary winding turns to the primary winding turns; t is any time within a cycle; The inductor current is: (2) The output current is: (3) Current i 1 flows through Q 1. L , T r1 Original edge, C 1 and i 1 is in increasing state, current i 2 flows successively Q 1. T r2 Original edge, Q 4. C 2. C 1. Such as Figure 3 shown.

[0025] Mode 2[ t 1, t 2]: t 1 moment Q 4 Shutdown, i 2 for Q The parasitic capacitance of 4 is charged to Q 3. The parasitic capacitor is discharged. Since the voltage across the capacitor cannot change suddenly, Q 4 can achieve ZVS shutdown. Q 3When the voltage across the parasitic capacitor is less than 0, Q 3 body diode conduction, i 2 Flow through Q 3 body diode. t 1 moment i 2 is relatively large, and the parasitic capacitance charging and discharging time is very short and can be ignored.

[0026] In this mode, the voltage across the inductor is: (4) The inductor current is: (5) Current i 1 flows throughQ 1. L , T r1 Original edge, C 1 and i 1 is in decreasing state, current i 2 flows successively Q 1. T r2 Original edge, Q 3 body diodes, such as Figure 4 shown.

[0027] Mode 3[ t 2, t 3]: t At moment 2, the current in the converter decays to 0. Q 3 body diode, D 1. D 4Natural shutdown, at this time Q 3 The voltage across the parasitic capacitor is 0. Q 4The voltage across the parasitic capacitor is Due to the unidirectional current-carrying characteristics of the output side forward power full bridge, the current in the converter remains at 0, and the output side capacitor C O Supply power to the load. t At moment 3, the positive half cycle ends. Q 1 off, Q 2. Q 3 conduction. L The rapid rise of the current in the converter is limited, and the current in the converter remains at 0 when the switch tube switches. Q 1 Achieved ZCS shutdown, Q 2. Q 3 achieves ZCS conduction. In addition, due to Q 3 The voltage across the two ends is 0, Q 3 actually realizes ZVZCS conduction. The modal current path is as follows Figure 5 shown.

[0028] The negative half-cycle switch trigger signal is as follows: Figure 2 shown.

[0029] In summary, the soft switching characteristics of each switch tube during forward transmission of BPAHDC energy are shown in Table 1.

[0030]

[0031] Energy reverse transfer mode: The waveform of BPAHDC in the reverse energy transfer state is as follows Figure 6 As shown, the current i in and i oThe reference direction is Figure 7 As shown. When energy is transferred in the reverse direction, S 5 is always in the off state. Similarly, in the positive half cycle, BPAHDC can be divided into three modes, namely: Mode 1[ t 0, t 1]: t 0 is the moment when a cycle starts. Q 1 conduction, Q 2 off, S 1. S 4 conduction, S 2. S 3 off, Q 3 opened. t Before time 0, no current flows through the converter. Q 1. S 1. S 4. Q 3 is ZCS conduction, Q 2. S 2. S 3 is ZCS shutdown.

[0032] In this mode, the inductor L The voltage across the terminals is: (6) The inductor current is: (7) Output Current: (8) Current i 1 Flow Q 1 anti-parallel diode, C 1. T r1 Original edge, L and i 1 is in decreasing state, current i 2 Flow Q 1 anti-parallel diode, Q 3. T r2 The modal current path is as follows Figure 8 shown.

[0033] Mode 2[ t 1, t 2]: t 1 moment Q 3 off, i 2 for Q 3 parasitic capacitance is charged to Q4's parasitic capacitor discharges. Since the voltage across the capacitor cannot change suddenly, Q 3 can achieve ZVS shutdown. Q 4 When the voltage across the parasitic capacitor is less than 0, Q 4 body diode conduction, i 2 Flow through Q 4 body diodes. t 1 moment i 2 is relatively large, and the parasitic capacitance charging and discharging time is very short and can be ignored.

[0034] In this mode, the voltage across the inductor is: (9) The inductor current is: (10) Current i 1 flows through Q 1 anti-parallel diode, C i1 , T r1 Original edge, L and i 1 is in increasing state, current i 2 flows successively Q 1 anti-parallel diode, C i1 , C i2 , Q 4 body diode, T r2 Original edge, such as Fig. 9 shown.

[0035] Mode 3[ t 2, t 3]: t At moment 2, the current in the converter decays to 0. Q 4 The body diode is naturally turned off. Q 4 The voltage across the parasitic capacitor is 0. Q 3 The voltage across the parasitic capacitor is Due to the single-phase current-carrying characteristics of the full-bridge on the output side, the current in the converter remains at 0, and the capacitor C 1. C 2 Supply power to the load. t At moment 3, the positive half cycle ends. Q 1. S 1. S 4 Shutdown, Q 2. Q 4. S 2. S 3 conduction. LThe rapid rise of the current in the converter is limited, and the current in the converter remains at 0 when the switch tube switches. Q 1. S 1. S 4 implements ZCS shutdown, Q 2. Q 4. S 2. S 3 realizes ZCS conduction. The modal current path is as follows Fig.10 shown.

[0036] The negative half-cycle switch trigger signal is as follows: Figure 6 As shown, the negative half cycle operates in a similar way to the positive half cycle. t 4 moments, due to the current i 2From Q 4Transfer to Q 3 body diodes, so i O Appeared with i 2 transitions of equal magnitude.

[0037] In summary, the soft switching characteristics of each switch tube during BPAHDC energy reverse transmission are shown in Table 2.

[0038]

[0039] In order to further illustrate the present invention, a simulation example is provided below for verification.

[0040] according to Figure 1 The BPAHDC topology shown in the figure is used to build a simulation platform in MATLAB / Simulink, and the simulation parameters are shown in Table 3.

[0041]

[0042] Energy forward transfer simulation results: Fig.11 Figure 1 is the BPAHDC output voltage waveform. It can be seen that the output voltage fluctuates around 750V, with a fluctuation range of about 30V.

[0043] Fig.12 is the BPAHDC inductor current i 1 waveform. It can be seen from the figure i 1 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, the inductor current does not change strictly according to the linear law.

[0044] Fig.13 Shown Q1 Voltage and current waveform. It can be seen that before turning on and off, the current flowing through Q The current of 1 is 0, Q 1. Realize ZCS opening and closing.

[0045] Fig.14 Shown Q 3 Voltage and current waveforms. From the figure, we can see that the voltage remains at 0 before forward conduction, and the current is also 0, so Q 3 ZVZCS was opened. Q 3 Before shutdown, due to the existence of parasitic capacitance, the voltage across the two ends cannot rise quickly, but rises linearly after the current drops to 0. Q 3 Achieved ZVS shutdown.

[0046] Energy reverse transfer simulation results: Fig.15 This is the output voltage waveform under reverse energy transfer. It can be seen that the output voltage fluctuates around 2000V, with a fluctuation range of about 5V.

[0047] Fig.16 The inductor current under reverse energy transfer i 1 waveform. It can be seen from the figure i 1 is in a discontinuous state, and the first half cycle is negative, 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, the inductor current does not change strictly according to the linear law.

[0048] Fig.17 The figure shows the reverse energy transfer state. Q 1 Voltage and current waveform. It can be seen that before turning on and off, the current flowing through Q The current of 1 is 0, Q 1. Realize ZCS opening and closing.

[0049] Fig.18 The energy is transferred in reverse direction. Q 3 Voltage and current waveforms. From the figure, we can see that the voltage and current are 0 before forward conduction, so Q 3 ZCS was activated. Q 3 Before shutdown, due to the existence of parasitic capacitance, the voltage across the two ends cannot rise quickly, but rises linearly after the current drops to 0. Q 3 Achieved ZVS shutdown.

[0050] Fig.19 The energy is transferred in reverse direction. S 1 Voltage and current waveform. It can be seen that before turning on and off, the current flowing through S 11 The current is 0.S 1. Realize ZCS opening and closing.

[0051] 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 global soft-switching heterogeneous DC converter adapted to bidirectional power requirements, characterized in that: include: Input side main power branch, input side auxiliary power branch, transformer group, output side reverse power full bridge and output side forward power full bridge; Input voltage The positive and negative electrodes are connected to the input capacitor C 1 and C 2. Input Capacitance C 1 and C 2 are respectively connected to the main power branches on the input side; The main power branch on the input side includes IGBTs in series with anti-parallel diodes. Q 1 and Q 2. The input side auxiliary power branch includes a series MOSFET Q 3 and Q 4. Transformer group includes main power transformer T r1 and auxiliary power transformer T r2 ; Q 1 and Q 2 Series nodes through the transmission inductor L and T r1 The primary side is connected to the input capacitor C 1 and C 2 connected nodes and T r1 The original edges are directly connected. Q 3 and Q 4 and T r2 The original edges of are connected; The output side reverse power full bridge includes reverse resistance IGBT S 1~ S 4, among which S 1's emitter and S 2's collector is connected, S 3's emitter and S 4's collector is connected, S 1 collector and S The collectors of 3 are connected to the output capacitor C o The positive electrode, S 2 emitter and S The emitters of 4 are connected to the output capacitor C o The negative electrode; The output side forward power full bridge includes diodes D 1~ D 4 and IGBT S 5. D 1 anode and D 2's cathodes are connected, D 3 anode and D 4's cathode is connected, D 1 and D The cathode of 3 is S 5's collector is connected, S The emitter of 5 is connected to C o The positive electrode, D 2 and D The anodes of 4 are C o The negative pole is connected; S 1's emitter and S 2 collectors form a node and D 1 anode and D 2 cathode nodes are formed with T r1 The secondary side is connected to the same-named end; S 3's emitter and S 4 forms a node with the collector and D 3 anode and D 4 cathode nodes are formed with T r2 The secondary side opposite ends are connected.

2. A global soft-switching heterogeneous DC converter adapted to bidirectional power requirements according to claim 1, characterized in that: C 1's negative electrode and C 2 positive poles are connected, the main power bridge arm Q 1's emitter and Q 2 is connected to the collector of the auxiliary power bridge arm. Q 3 source and Q 4's drain is connected, C 1 are connected to the positive electrode Q 1 collector, Q 3. The drain and input voltage The positive electrode, C 2 are connected to the negative poles Q 2 emitter, Q 4 source and The negative electrode, C 1's negative electrode and C 2 The positive terminal is connected to the T r1 The original side of the antonym end; T r1 The primary side of the same name and the transmission inductor L One end is connected to T r2 The same-name end of the original edge L The other end of is connected to the Q 1's emitter and Q 2's collector junction, Q 3 source and Q The node connected to the drain of 4 is connected to T r2 The original side of the antonym end; T r1 The secondary side synonymous end and T r2 The secondary side of is connected to the same-name end.

3. A method for operating a global soft-switching heterogeneous DC converter adapted to bidirectional power requirements, based on a global soft-switching heterogeneous DC converter adapted to bidirectional power requirements as claimed in any one of claims 1-2, characterized in that: include: Energy forward transfer mode and energy reverse transfer mode; In the forward energy transfer mode, S 1~ S 4 Keep off state, S 5 Keep the conduction state; divide the positive half cycle into [ t 0 , t 1) [ t 1, t 2) and [ t 2, t 3] Three time periods; the negative half cycle and the positive half cycle are symmetrical; [ t 0 , t 1 ) time period, Q 1 and Q 4 conduction, Q 2 and Q 3 off, D 1 and D 4 conduction, D 2 and D 3 shutdown, where t 0 time, Q 1 and Q 4 is ZCS conduction, Q 2. D 2 and D 3 is ZCS shutdown, D 1 and D 4Natural conduction; current i 1 flows through Q 1. L , T r1 Original edge and C 1, and i 1 is in increasing state, current i 2 flows successively Q 1. T r2 Original edge, Q 4. C 2 and C 1, and i 2 is in increasing state; [ t 1, t 2) During the time period, Q 1 Keep conducting, Q 2 and Q 3 Keep off, Q 4 Shutdown, D 1 and D 4 Keep conducting, D 2 and D 3 remains off, where t 1 moment Q 4 to achieve ZVS shutdown, i 2 for Q The parasitic capacitance of 4 is charged to Q 3 The parasitic capacitance is discharged when Q When the voltage across the parasitic capacitor of 3 is less than 0, Q 3's body diode conducts, i 2 Flow through Q 3 Body diode; current i 1 flows through Q 1. L , T r1 Original edge and C 1, and i 1 is in decreasing state, current i 2 flows successively Q 1. T r2 Original edge and Q 3 body diodes, and i 2 is in decreasing state; [ t 2, t 3] During the time period, Q 1 Keep conducting, Q 2. Q 3 and Q 4 Keep off, D 1. D 2. D 3 and D 4 are all turned off, among which, t 2 Moment, current i 1 and i 2 decays to 0, Q 3 body diode, D 1 and D 4Natural shutdown, Q The voltage across the parasitic capacitor of 3 is 0. Q The voltage across the parasitic capacitor of 4 is , by the output capacitor C o Supply power to the load; t 3 The positive half cycle ends at this moment. Q 1 off, Q 2 and Q 3 conduction, L Limit the rapid rise of current in the converter, the current i 1 and i 2 remains at 0, then Q 1 to achieve ZCS shutdown, Q 2 to achieve ZCS conduction, Q 3. Realize ZVZCS conduction; In the reverse energy transfer mode, S 5 Keep the off state; divide the positive half cycle into [ t 0 , t 1) [ t 1, t 2) and [ t 2, t 3] Three time periods; the negative half cycle and the positive half cycle are symmetrical; [ t 0 , t 1 ) time period, S 1 and S 4 conduction, Q 1 and Q 3 conduction, Q 2 and Q 4 is turned off, and t 0 time Q 1. S 1. S 4 and Q 3 is ZCS conduction, Q 2. S 2 and S 3 is ZCS shutdown; current i 1 Flow Q 1 anti-parallel diode, C 1. T r1 Original edge and L ,and i 1 is in decreasing state, current i 2 Flow Q 1 anti-parallel diode, Q 3 and T r2 The original edge, and i 2 is in decreasing state; [ t 1, t 2) During the time period, S 1 and S 4 Keep conducting, Q 1 Keep conducting, Q 2. Q 3 and Q 4 Shutdown, in t 1 moment, i 2 for Q 3 parasitic capacitance is charged to Q 4 discharges the parasitic capacitance, Q 3 To achieve ZVS shutdown, when Q When the voltage across the parasitic capacitor of 4 is less than 0, Q The body diode of 4 is conducting, i 2 Flow through Q 4 Body diode; current i 1 flows through Q 1 anti-parallel diode, C i1 , T r1 Original edge and L ,and i 1 is in increasing state, current i 2 flows successively Q 1 anti-parallel diode, C i1 , C i2 , Q 4 body diode and T r2 The original edge, and i 1 is in increasing state; [ t 2, t 3] During the time period, S 1 and S 4 Keep conducting, Q 1 Keep conducting, Q 2. Q 3 and Q 4 Shutdown, in t At moment 2, the current in the converter decays to 0. Q The body diode of 4 is naturally turned off, t 2 Moments Q 4 The voltage across the parasitic capacitor is 0. Q The voltage across the parasitic capacitor of 3 is Due to the single-phase current-carrying characteristics of the full-bridge on the output side, the current in the converter remains at 0, and the capacitor C 1 and C 2. Supply power to the load; t At moment 3, the positive half cycle ends. Q 1. S 1 and S 4. Achieve ZCS shutdown, Q 2. Q 4. S 2 and S 3. Achieve ZCS conduction.

4. The method for operating a global soft-switching heterogeneous DC converter adapted to bidirectional power demand according to claim 3 is characterized in that: In the energy forward transfer mode [ t 0 , t 1 ) during the time period: inductance L The voltage across the terminals is: (1) In the formula, V o is the output voltage, N 1 and N 2 are T r1 and T r2 The ratio of the secondary winding turns to the primary winding turns; t is any time within a cycle; The inductor current is: (2) The output current is: (3)。 5. The method for operating a global soft-switching heterogeneous DC converter adapted to bidirectional power demand according to claim 3, characterized in that: In the energy forward transfer mode [ t 1, t 2) During the time period: The voltage across the inductor is: (4) The inductor current is: (5)。 6. The method for operating a global soft-switching heterogeneous DC converter adapted to bidirectional power demand according to claim 3, characterized in that: In the reverse energy transfer mode [ t 0 , t 1 ) during the time period: inductance L The voltage across the terminals is: (6) The inductor current is: (7) Output Current: (8)。 7. The method for operating a global soft-switching heterogeneous DC converter adapted to bidirectional power demand according to claim 3, characterized in that: In the reverse energy transfer mode [ t 1, t 2) During the time period: The voltage across the inductor is: (9) The inductor current is: (10)。 8. The method for operating a global soft-switching heterogeneous DC converter adapted to bidirectional power demand according to claim 3, characterized in that: In the energy reverse transfer mode, the first time period in the negative half cycle is ( t 3, t 4], t 4 Moment, current i 2From Q 4Transfer to Q 3 body diodes, i o Appearance and i 2 transitions of equal magnitude.

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