Vehicle-mounted three-port dc converter reverse pre-charge control method

Abstract

The application discloses a reverse pre-charging control method of a vehicle-mounted three-port DC converter, a bus capacitor is connected between two ends of an A port, and a high-voltage electrical equipment capacitor is connected between two ends of a B port; a first switch is connected in series in a loop from the bus capacitor to commercial power; a high-voltage battery is connected in parallel to the high-voltage electrical equipment capacitor after being connected in series with a second switch; the C port circuit, the B port circuit and the A port circuit can all realize bidirectional power transmission; by controlling the turn-on and turn-off time sequence of the switch tubes in the A port circuit, the B port circuit and the C port circuit, the vehicle-mounted three-port DC converter is enabled to work in pre-charging mode 1 to realize energy transmission from a low-voltage battery to the A port and the B port at the same time, or the vehicle-mounted three-port DC converter is enabled to work in pre-charging mode 2 to realize energy transmission from the low-voltage battery to the B port only. The reverse pre-charging control method of the vehicle-mounted three-port DC converter does not increase the cost of additional hardware, reduces the cost and volume of the vehicle-mounted charging device, can realize energy transmission from the C port to the A port and the B port at the same time, and saves pre-charging time.

Description

Technical Field

[0001] This invention relates to circuits, and more particularly to a reverse precharge control method for an on-board three-port DC-DC converter. Background Technology

[0002] With the increasing emphasis on energy conservation and emission reduction in various countries, the electric vehicle market is gradually expanding. On-board chargers (OBC / DCDC), serving as the interface between mains power, low-voltage (below 50V) batteries, and high-voltage (above 100V) batteries, play a crucial role in the vehicle. The high-voltage electrical equipment in the vehicle and the DC bus inside the on-board charger typically contain large capacitors in the mF range. Directly charging these large capacitors without control can generate extremely large inrush currents, easily damaging related components.

[0003] Existing technology typically involves adding a pre-charge branch for pre-charging a large capacitor. This pre-charge branch usually includes a pre-charge resistor, a pre-charge relay, or a PTC (Positive Temperature Coefficient) resistor. For example... Figure 1 As shown, before closing the main relay switches K1 and K2, the bus capacitor C is first charged through the pre-charge branch. BUS and capacitor C of high-voltage electrical equipment HV Perform slow charging, and close the main relay only when the voltage of the large capacitor approaches the target voltage. For capacitor C in high-voltage electrical equipment... HV Low-voltage batteries (BAT) can also be used. LV The capacitor C of high-voltage electrical equipment is converted using a low-voltage DC / DC converter. HV Pre-charge, such as Figure 2 As shown, the high-voltage battery BAT HV The pre-charge branch on the side can be saved.

[0004] Adding a pre-charge branch to the pre-charge method increases the size and cost of the charging device. Furthermore, the pre-charge resistance is fixed, meaning the pre-charge time is not adjustable, resulting in poor flexibility. Pre-charging via a low-voltage DC / DC converter can only pre-charge the capacitors of high-voltage equipment and cannot simultaneously pre-charge the internal bus capacitors of the OBC. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a reverse pre-charge control method for a vehicle-mounted three-port DC-DC converter, which realizes the reverse pre-charge function without increasing the additional hardware cost, thereby reducing the cost and size of the vehicle-mounted charging device.

[0006] To address the aforementioned technical problems, this invention provides a reverse pre-charge control method for an on-board three-port DC-DC converter. The on-board three-port converter includes an A-port circuit, a B-port circuit, and a C-port circuit. The B-port circuit, along with the A-port and C-port circuits, transmits energy via a transformer. Port A of the A-port circuit is connected to the PFC bus of the on-board charger, and port B of the B-port circuit is connected to the high-voltage battery (BAT). HV The C port of the C-port circuit is used to connect to the low-voltage battery BAT. LV A bus capacitor C is connected between the two ends of port A. BUS A high-voltage electrical equipment capacitor C is connected in parallel between the two ends of port B. HV ;

[0007] Bus capacitor C BUS A first switch K1 is connected in series in the circuit to the mains power supply;

[0008] High-voltage battery BAT HV After being connected in series with the second switch K2, it is connected in parallel to the capacitor C of the high-voltage electrical equipment. HV Both ends;

[0009] The C-port circuit, B-port circuit, and A-port circuit can all achieve bidirectional power transmission.

[0010] By controlling the turn-on and turn-off timing of the switching transistors in the A-port, B-port, and C-port circuits, the on-board three-port DC-DC converter is made to operate in pre-charge mode 1 to achieve low-voltage battery BAT. LV Simultaneously transfer energy to ports A and B, or enable the onboard three-port DC-DC converter to operate in pre-charge mode 2 to achieve low-voltage battery BAT. LV Energy is transferred only to port B.

[0011] Preferably, the C-port circuit adopts a full-wave rectification structure, a full-bridge rectification structure, or a current-doubler rectification structure.

[0012] Preferably, the mains power is single-phase AC or three-phase AC.

[0013] Preferably, the first switch K1 and the second switch K2 are relay switches.

[0014] Preferably, the following steps are included:

[0015] S1. Connect the charging gun to wake up the vehicle's three-port DC-DC converter;

[0016] S2. Enable the on-board three-port DC-DC converter to operate in pre-charge mode 1, low-voltage battery BAT LV Energy is transferred to both port A and port B simultaneously.

[0017] S3. When V BUS -V AC_PK >VTH_BUS V BUS For bus capacitor C BUS Bus voltage at both ends, V AC_PK The peak value of the AC input voltage of the on-board charger, V TH_BUS If the bus threshold voltage is reached, then the first switch K1 is closed, and the gate drive signals of each switch in the A-port circuit are stopped, proceeding to step S4; when V BUS -V AC_PK ≤V TH_BUS Then proceed to step S2;

[0018] S4. Enable the on-board three-port DC-DC converter to operate in pre-charge mode 2, low-voltage battery BAT LV Energy is transferred only to port B;

[0019] S5. When V HV –V HV_CMD >V TH_HV V HV For high-voltage electrical equipment capacitor C HV Voltage across terminals, V HV_CMD For the target high pressure,

[0020] V TH_HV If the voltage is the high-voltage threshold voltage, then close the second switch K2 and proceed to step S6; when V HV –V HV_CMD ≤V TH_HV Then proceed to step S4;

[0021] S6. End pre-charging.

[0022] Preferably, in step S3, when V BUS -V AC_PK ≤V TH_BUS If the duration is less than or equal to the first set time, proceed to step S2; if the duration is greater than the first set time, enter a fault state.

[0023] Preferably, in step S5, when V HV –V HV_CMD ≤V TH_HV If the duration is less than or equal to the second set time, proceed to step S4; if the duration is greater than the second set time, enter a fault state.

[0024] Preferably, the vehicle-mounted three-port converter includes a first transformer T1 and a second transformer T2, wherein the first transformer T1 and the second transformer T2 are independent of each other;

[0025] The first transformer T1 includes a first magnetic core, an A-port side winding n1, and a first B-port side winding n2;

[0026] The second transformer T2 includes a second magnetic core, a second B-port side winding n3, and a C-port side winding;

[0027] The C-port side winding includes a C-port side first winding n4 and a C-port side second winding n5;

[0028] The A-port circuit includes a first switch S1, a second switch S2, a third switch S3, and a fourth switch S4; the first switch S1 and the second switch S2 form a first bridge arm, and the third switch S3 and the fourth switch S4 form a second bridge arm; the midpoints of the first bridge arm and the second bridge arm are respectively connected to the two ends of the A-port side winding n1 of the first transformer T1, and the two ends of the first bridge arm and the second bridge arm serve as the A-port;

[0029] The B-port circuit includes a fifth switch S5, a sixth switch S6, a seventh switch S7, an eighth switch S8, a ninth switch S9, and a tenth switch S10; the fifth switch S5 and the sixth switch S6 form the third bridge arm; the seventh switch S7 and the eighth switch S8 form the fourth bridge arm; the ninth switch S9 and the tenth switch S10 form the fifth bridge arm; the two ends of the third, fourth, and fifth bridge arms serve as B-ports; the two ends of the first B-port side winding n2 are respectively connected to the midpoints of the third and fourth bridge arms; the two ends of the second B-port side winding n3 are respectively connected to the midpoints of the fourth and fifth bridge arms.

[0030] The C-port circuit includes an eleventh switch S11, a twelfth switch S12, a thirteenth switch S13, and a fourteenth switch S14.

[0031] The source and drain terminals of the twelfth switching transistor S12 are respectively connected to the same-name terminal of the first winding n4 on the C port side and the working low-voltage negative terminal LV-.

[0032] The source and drain terminals of the eleventh switching transistor S11 are respectively connected to the opposite-name terminal of the second winding n5 on the C port side and the working low-voltage negative terminal LV-.

[0033] One end of the source and drain of the fourteenth switch S14 is connected to the same-name terminal of the first winding n4 on the C port side, and the other end is connected to the working low voltage negative terminal LV- via the second clamping capacitor C2.

[0034] One end of the source and drain of the thirteenth switch S13 is connected to the opposite-name terminal of the second winding n5 on the C port side, and the other end is connected to the working low voltage negative terminal LV- via the first clamping capacitor C1.

[0035] One end of the filter inductor Lo is connected to the low-voltage positive terminal LV+, and the other end is connected to the opposite-name terminal of the first winding n4 on the C port side and the same-name terminal of the second winding n5 on the C port side.

[0036] Preferably, the switching transistors in the A-port circuit, B-port circuit, and C-port circuit all have the same on-frequency fs;

[0037] To enable the onboard three-port DC-DC converter to operate in pre-charge mode 1, low-voltage battery BAT is achieved. LV When energy is transferred to both port A and port B simultaneously, the first switch K1 and the first switch K2 are disconnected:

[0038] In the C-port circuit, the eleventh switch S11 and the twelfth switch S12 are complementary in conducting, and their conduction durations are both DT. S The duty cycle is D;

[0039] The thirteenth switch S13 and the fourteenth switch S14 are complementary and conduct.

[0040] When the thirteenth switch S13 is turned on, the eleventh switch S11 is turned off and the twelfth switch S12 is turned on.

[0041] When the fourteenth switch S14 is turned on, the eleventh switch S11 is turned on and the twelfth switch S12 is turned off.

[0042] In the B-port circuit, the switching sequence of the fifth switch S5, the eighth switch S8, and the ninth switch S9 is the same as that of the thirteenth switch S13.

[0043] The switching sequence of the sixth switch S6, the seventh switch S7 and the tenth switch S10 is the same as that of the fourteenth switch S14.

[0044] As the voltage between the two ends of port B of the high-voltage battery gradually increases, the duty cycle D of the eleventh switch S11 and the twelfth switch S12 gradually increases from 0.

[0045] When D≤0.5, the first switch S1, the second switch S2, the third switch S3 and the fourth switch S4 in the A-port circuit are all turned off, and the circuit operates in passive rectification mode through the body diode.

[0046] The eleventh switch S11, the fourteenth switch S14, the sixth switch S6, the seventh switch S7, and the tenth switch S10 are simultaneously turned on, with the same on-time DT. S ;

[0047] The twelfth switch S12, the thirteenth switch S13, the fifth switch S5, the eighth switch S8, and the ninth switch S9 are simultaneously turned on, with the same on-time DT. S ;

[0048] When D>0.5, the first switch S1, the second switch S2, the third switch S3 and the fourth switch S4 in the A port circuit work in PWM mode, and the duty cycle of each switch is 1-D.

[0049] The first switch S1 and the fourth switch S4 are turned on simultaneously;

[0050] The second switch S2 and the third switch S3 are turned on simultaneously;

[0051] The second switch S2 is 180° out of phase with the first switch S1.

[0052] The conduction phase of the first switch S1 leads the fifth switch S5 by 0° to 150°;

[0053] The thirteenth switch S13 and the eleventh switch S11 are complementary in conduction.

[0054] The fourteenth switch S14 and the twelfth switch S12 are complementary in conduction;

[0055] The eleventh switch S11 and the twelfth switch S12 are 180 degrees out of phase.

[0056] Preferably, the duty cycle D of the eleventh switch S11 and the twelfth switch S12 in the C-port circuit is jointly determined by the C-port current control loop and the B-port voltage control loop.

[0057] When the voltage at port B reaches the target voltage at port B, the second switch K2 is turned on.

[0058] Preferably, the angle by which the conduction phases of the second switch S2 and the first switch S1 lead or lag the fifth switch S5 is determined by the A-port voltage control loop.

[0059] When the voltage at port A reaches the target voltage at port A, the first switch K1 is turned on.

[0060] Preferably, the onboard three-port DC-DC converter operates in pre-charge mode 2 to achieve low-voltage battery BAT. LV When energy is transferred only to port B:

[0061] Disconnect the second switch K2;

[0062] In the C-port circuit, the eleventh switch S11 and the twelfth switch S12 are complementary in conducting, and their conduction durations are both DT. S The duty cycle is D;

[0063] The thirteenth switch S13 and the fourteenth switch S14 are complementary and conduct.

[0064] When the thirteenth switch S13 is turned on, the eleventh switch S11 is turned off and the twelfth switch S12 is turned on.

[0065] When the fourteenth switch S14 is turned on, the eleventh switch S11 is turned on and the twelfth switch S12 is turned off.

[0066] When the thirteenth switch S13 is turned on, the eleventh switch S11 is turned off and the twelfth switch S12 is turned on.

[0067] When the fourteenth switch S14 is turned on, the eleventh switch S11 is turned on and the twelfth switch S12 is turned off.

[0068] As the voltage between the two ends of port B of the high-voltage battery gradually increases, the duty cycle D of the eleventh switch S11 and the twelfth switch S12 gradually increases from 0.

[0069] In the B-port circuit, the fifth switch S5, the sixth switch S6, the seventh switch S7, the eighth switch S8, the ninth switch S9, and the tenth switch S10 are all turned off.

[0070] In the A-port circuit, the first switch S1 and the third switch S3 remain off, while the second switch S2 and the fourth switch S4 remain off and are normally on.

[0071] Preferably, the second switch K2 is turned on when the voltage at port B reaches the target voltage at port B.

[0072] Preferably, the positive terminal of the first diode D1 is connected to the opposite terminal of the second winding n5 on the C port side, and the negative terminal is connected to the working low voltage negative terminal LV- via the first clamping capacitor C1;

[0073] The positive terminal of the second diode D2 is connected to the same-name terminal of the first winding n4 on the C port side, and the negative terminal is connected to the working low-voltage negative terminal LV- via the second clamping capacitor C2.

[0074] Preferably, the eleventh switch S11, the twelfth switch S12, the thirteenth switch S13 and the fourteenth switch S14 are all insulated gate enhancement type NMOS transistors.

[0075] The source terminal of the eleventh switch S11, the source terminal of the twelfth switch S12, the drain terminal of the thirteenth switch S13, and the drain terminal of the fourteenth switch S14 are all connected to the working low-voltage negative terminal LV-.

[0076] Preferably, the C-port circuit further includes a filter capacitor Co;

[0077] The two ends of the filter capacitor Co are connected to the positive terminal LV+ and the negative terminal LV- of the low working voltage, respectively.

[0078] Preferably, the A-port circuit further includes a resonant inductor Lr, a resonant capacitor Cr, and a magnetizing inductor Lm;

[0079] The two ends of the resonant inductor Lr are respectively connected to the midpoint of the first bridge arm and the corresponding terminal of the winding n1 on the A port side;

[0080] The two ends of the resonant capacitor Cr are respectively connected to the midpoint of the second bridge arm and the opposite end of the winding n1 on the A port side.

[0081] The two ends of the excitation inductor Lm are respectively connected to the midpoint of the second bridge arm and the two ends of the winding n1 on the A port side.

[0082] Preferably, the B-port circuit further includes a leakage inductance Ls;

[0083] The leakage inductance Ls is connected at both ends to the midpoint of the fifth bridge arm and the opposite-name terminal of the second B port winding n3, respectively.

[0084] The reverse pre-charge control method for a vehicle-mounted three-port DC-DC converter of the present invention does not require the addition of pre-charge branches at port A (bus port) and port B (high-voltage battery port), and can simultaneously perform reverse pre-charge on the large capacitors at ports A (bus port) and B (high-voltage battery port). The reverse pre-charge function does not increase the additional hardware cost, reducing the cost and size of the vehicle-mounted charging device. It can also simultaneously transfer energy from port C to ports A and B, saving pre-charge time. Attached Figure Description

[0085] To more clearly illustrate the technical solution of the present invention, the accompanying drawings used in the present invention will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0086] Figure 1 This is a circuit diagram of a DC-DC converter that uses a pre-charge resistor and a relay for pre-charging.

[0087] Figure 2 This is a circuit diagram of a DC-DC converter that performs pre-charging via a low-voltage DC / DC converter.

[0088] Figure 3 This is a schematic diagram of the reverse precharge control method for the vehicle-mounted three-port DC-DC converter of the present invention;

[0089] Figure 4 This is an embodiment of the vehicle-mounted three-port DC-DC converter reverse precharge control method of the present invention, showing the vehicle-mounted three-port DC-DC converter topology.

[0090] Figure 5This is the driving timing sequence of the switching transistors at each port in precharge mode 1 of an embodiment of the reverse precharge control method for a vehicle-mounted three-port DC-DC converter of the present invention.

[0091] Figure 6 This is the driving timing sequence of the switching transistors at each port when operating in precharge mode 2, according to an embodiment of the reverse precharge control method for a vehicle-mounted three-port DC-DC converter of the present invention.

[0092] Figure 7 This is a block diagram of the voltage and current control loop, duty cycle, and phase calculation of an embodiment of the reverse precharge control method for an on-board three-port DC-DC converter of the present invention;

[0093] Figure 8 This is a flowchart illustrating the reverse precharge process of an embodiment of the reverse precharge control method for a vehicle-mounted three-port DC-DC converter according to the present invention. Detailed Implementation

[0094] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0095] The terms "first," "second," and similar words used in this application do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Words such as "including" or "comprising" mean that the element or object preceding the word encompasses the elements or objects listed after the word and their equivalents, without excluding other elements or objects. Words such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0096] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0097] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but this is not intended to limit the scope of the invention.

[0098] Example 1

[0099] A reverse precharge control method for an on-board three-port DC-DC converter, such as Figure 3As shown, the vehicle-mounted three-port converter includes an A-port circuit, a B-port circuit, and a C-port circuit; the B-port circuit transmits energy to the A-port circuit and the C-port circuit through a transformer.

[0100] Port A of the circuit is used to connect to the PFC (Power Factor Correction) bus of the on-board charger, and Port B of the circuit is used to connect to the high-voltage (above 100V) battery BAT. HV The C port of the C-port circuit is used to connect a low-voltage (below 50V) battery BAT. LV ;

[0101] A bus capacitor C is connected between the two ends of port A (bus port). BUS A capacitor C from the high-voltage electrical equipment is connected in parallel between the two ends of port B (high-voltage battery port). HV ;

[0102] Bus capacitor C BUS A first switch K1 is connected in series in the circuit to the mains power supply;

[0103] High-voltage battery BAT HV After being connected in series with the second switch K2, it is connected in parallel to the capacitor C of the high-voltage electrical equipment. HV Both ends;

[0104] The C-port circuit, B-port circuit, and A-port circuit can all achieve bidirectional power transmission.

[0105] By controlling the turn-on and turn-off timing of the switching transistors in the A-port, B-port, and C-port circuits, the on-board three-port DC-DC converter is made to operate in pre-charge mode 1 to achieve low-voltage battery BAT. LV Simultaneously transfer energy to ports A and B, or enable the onboard three-port DC-DC converter to operate in pre-charge mode 2 to achieve low-voltage battery BAT. LV Energy is transferred only to port B.

[0106] Preferably, the C-port circuit adopts a full-wave rectification structure, a full-bridge rectification structure, or a current-doubling rectification structure.

[0107] Preferably, the mains power is single-phase AC or three-phase AC.

[0108] Preferably, the first switch K1 and the second switch K2 are relay switches.

[0109] The reverse pre-charge control method for the vehicle-mounted three-port DC-DC converter in Embodiment 1 does not require adding pre-charge branches to ports A (bus port) and B (high-voltage battery port). It can simultaneously perform reverse pre-charge on the large capacitors of ports A (bus port) and B (high-voltage battery port), realizing the reverse pre-charge function without increasing additional hardware costs, reducing the cost and size of the vehicle-mounted charging device, and enabling energy transfer from port C to ports A and B at the same time, saving pre-charge time.

[0110] Example 2

[0111] The reverse pre-charge control method for an on-board three-port DC-DC converter based on Embodiment 1, such as Figure 8 As shown, it includes the following steps:

[0112] S1. Connect the charging gun to wake up the vehicle's three-port DC-DC converter;

[0113] S2. Enable the on-board three-port DC-DC converter to operate in pre-charge mode 1, low-voltage battery BAT LV Energy is transferred to both port A and port B simultaneously.

[0114] S3. When V BUS -V AC_PK >V TH_BUS V BUS For bus capacitor C BUS Bus voltage at both ends, V AC_PK The peak value of the AC input voltage of the on-board charger, V TH_BUS If the bus threshold voltage is reached, then the first switch K1 is closed, and the gate drive signals of each switch in the A-port circuit are stopped, proceeding to step S4; when V BUS -V AC_PK ≤V TH_BUS Then proceed to step S2;

[0115] S4. Enable the on-board three-port DC-DC converter to operate in pre-charge mode 2, low-voltage battery BAT LV Energy is transferred only to port B;

[0116] S5. When V HV –V HV_CMD >V TH_HV V HV For high-voltage electrical equipment capacitor C HV Voltage across terminals, V HV_CMD For the target high pressure,

[0117] V TH_HV If the voltage is the high-voltage threshold voltage, then close the second switch K2 and proceed to step S6; when V HV –V HV_CMD ≤V TH_HV Then proceed to step S4;

[0118] S6. End pre-charging.

[0119] Preferably, in step S3, when V BUS -V AC_PK ≤V TH_BUS If the duration is less than or equal to the first set time, proceed to step S2; if the duration is greater than the first set time, enter a fault state.

[0120] Preferably, in step S5, when V HV –V HV_CMD ≤V TH_HV If the duration is less than or equal to the second set time, proceed to step S4; if the duration is greater than the second set time, enter a fault state.

[0121] The reverse pre-charge control method for the vehicle-mounted three-port DC-DC converter in Example 2 involves the charging gun being connected to wake up the vehicle-mounted three-port DC-DC converter, which then enters pre-charge working mode 1, causing the low-voltage (below 50V) battery BAT to... LV Energy is simultaneously transferred to port A (bus port) and port B (high-voltage battery port), and the on-board charger detects the bus capacitor C. BUS Bus voltage at both ends V BUS When the bus capacitance C BUS Bus voltage at both ends V BUS Greater than the peak value of the on-board charger's AC input voltage V AC_PK Exceeding the bus threshold voltage V TH_BUS At this time, the bus capacitor pre-charge is completed, the A port drive is stopped and the first switch K1 on the AC terminal is closed; then it enters pre-charge working mode 2, which enables the low-voltage (below 50V) battery BAT to... LV Energy is only transferred to port B (high-voltage battery port) when the capacitor C of the high-voltage electrical equipment... HV Voltage V at both ends HV Greater than the target high voltage V HV_CMD Exceeding the high voltage threshold voltage V TH_HV Then, the second switch K2 is closed, completing the connection of the capacitor C of the high-voltage electrical equipment. HV Pre-charging is performed. After pre-charging is completed, the vehicle can enter charging mode or PTC heating mode according to the instructions of VCU (Vehicle Control Unit).

[0122] Example 3

[0123] The reverse pre-charge control method for an on-board three-port DC-DC converter based on Embodiment 1, such as Figure 4 As shown, the vehicle-mounted three-port converter includes a first transformer T1 and a second transformer T2, which are independent of each other.

[0124] The first transformer T1 includes a first magnetic core, an A-port side winding n1, and a first B-port side winding n2;

[0125] The second transformer T2 includes a second magnetic core, a second B-port side winding n3, and a C-port side winding;

[0126] The C-port side winding includes a C-port side first winding n4 and a C-port side second winding n5;

[0127] The A-port circuit includes a first switch S1, a second switch S2, a third switch S3, and a fourth switch S4; the first switch S1 and the second switch S2 form a first bridge arm, and the third switch S3 and the fourth switch S4 form a second bridge arm; the midpoints of the first bridge arm and the second bridge arm are respectively connected to the two ends of the A-port side winding n1 of the first transformer T1, and the two ends of the first bridge arm and the second bridge arm serve as the A-port;

[0128] The B-port circuit includes a fifth switch S5, a sixth switch S6, a seventh switch S7, an eighth switch S8, a ninth switch S9, and a tenth switch S10; the fifth switch S5 and the sixth switch S6 form the third bridge arm; the seventh switch S7 and the eighth switch S8 form the fourth bridge arm; the ninth switch S9 and the tenth switch S10 form the fifth bridge arm; the two ends of the third, fourth, and fifth bridge arms serve as B-ports; the two ends of the first B-port side winding n2 are respectively connected to the midpoints of the third and fourth bridge arms; the two ends of the second B-port side winding n3 are respectively connected to the midpoints of the fourth and fifth bridge arms.

[0129] The C-port circuit includes an eleventh switch S11, a twelfth switch S12, a thirteenth switch S13, and a fourteenth switch S14.

[0130] The source and drain terminals of the twelfth switching transistor S12 are respectively connected to the same-name terminal of the first winding n4 on the C port side and the working low-voltage negative terminal LV-.

[0131] The source and drain terminals of the eleventh switching transistor S11 are respectively connected to the opposite-name terminal of the second winding n5 on the C port side and the working low-voltage negative terminal LV-.

[0132] One end of the source and drain of the fourteenth switch S14 is connected to the same-name terminal of the first winding n4 on the C port side, and the other end is connected to the working low voltage negative terminal LV- via the second clamping capacitor C2.

[0133] One end of the source and drain of the thirteenth switch S13 is connected to the opposite-name terminal of the second winding n5 on the C port side, and the other end is connected to the working low voltage negative terminal LV- via the first clamping capacitor C1.

[0134] One end of the filter inductor Lo is connected to the low-voltage positive terminal LV+, and the other end is connected to the opposite-name terminal of the first winding n4 on the C port side and the same-name terminal of the second winding n5 on the C port side.

[0135] The reverse precharge control method for the vehicle-mounted three-port DC-DC converter in Example 3 integrates high-voltage DC / DC and low-voltage DC / DC into a single topology, enabling power conversion between the AC port and the BC port.

[0136] Example 4

[0137] Based on the reverse precharge control method of the vehicle-mounted three-port DC-DC converter in Embodiment 3, the positive terminal of the first diode D1 is connected to the opposite terminal of the second winding n5 on the C port side, and the negative terminal is connected to the working low voltage negative terminal LV- through the first clamping capacitor C1.

[0138] The positive terminal of the second diode D2 is connected to the same-name terminal of the first winding n4 on the C port side, and the negative terminal is connected to the working low-voltage negative terminal LV- via the second clamping capacitor C2.

[0139] Preferably, the eleventh switch S11, the twelfth switch S12, the thirteenth switch S13 and the fourteenth switch S14 are all insulated gate enhancement type NMOS transistors.

[0140] The source terminal of the eleventh switch S11, the source terminal of the twelfth switch S12, the drain terminal of the thirteenth switch S13, and the drain terminal of the fourteenth switch S14 are all connected to the working low-voltage negative terminal LV-.

[0141] Better The C-port circuit also includes a filter capacitor Co;

[0142] The filter capacitor The two ends of Co are connected to the positive terminal LV+ and the negative terminal LV- of the low working voltage, respectively.

[0143] Preferably, the A-port circuit further includes a resonant inductor Lr, a resonant capacitor Cr, and a magnetizing inductor Lm;

[0144] The two ends of the resonant inductor Lr are respectively connected to the midpoint of the first bridge arm and the corresponding terminal of the winding n1 on the A port side;

[0145] The two ends of the resonant capacitor Cr are respectively connected to the midpoint of the second bridge arm and the opposite end of the winding n1 on the A port side.

[0146] The two ends of the excitation inductor Lm are respectively connected to the midpoint of the second bridge arm and the two ends of the winding n1 on the A port side.

[0147] The resonant inductor Lr, resonant capacitor Cr, and magnetizing inductor Lm form a resonant network.

[0148] Preferably, the B-port circuit further includes a leakage inductance Ls;

[0149] The leakage inductance Ls is connected at both ends to the midpoint of the fifth bridge arm and the opposite-name terminal of the second B port winding n3, respectively.

[0150] The vehicle-mounted three-port DC-DC converter in Example 4 uses full-wave rectification plus an active clamping circuit in its C-port circuit, which can further reduce the voltage stress on power devices and improve the charging efficiency of vehicle-mounted low-voltage batteries.

[0151] Example 5

[0152] The reverse pre-charge control method for an on-board three-port DC-DC converter based on Embodiment 3, such as Figure 5 As shown, the conduction frequency of the switching transistors in the A-port circuit, B-port circuit, and C-port circuit is the same: fs.

[0153] To enable the onboard three-port DC-DC converter to operate in pre-charge mode 1, low-voltage battery BAT is achieved. LV When energy is transferred to both port A and port B simultaneously, the first switch K1 and the first switch K2 are disconnected:

[0154] In the C-port circuit, the eleventh switch S11 and the twelfth switch S12 are complementary in conducting, and their conduction durations are both DT. S The duty cycle is D;

[0155] The thirteenth switch S13 and the fourteenth switch S14 are complementary and conduct.

[0156] When the thirteenth switch S13 is turned on, the eleventh switch S11 is turned off and the twelfth switch S12 is turned on.

[0157] When the fourteenth switch S14 is turned on, the eleventh switch S11 is turned on and the twelfth switch S12 is turned off.

[0158] In the B-port circuit, the switching sequence of the fifth switch S5, the eighth switch S8, and the ninth switch S9 is the same as that of the thirteenth switch S13.

[0159] The switching sequence of the sixth switch S6, the seventh switch S7 and the tenth switch S10 is the same as that of the fourteenth switch S14.

[0160] As the voltage between the two ends of port B of the high-voltage battery gradually increases, the duty cycle D of the eleventh switch S11 and the twelfth switch S12 gradually increases from 0.

[0161] When D≤0.5, the first switch S1, the second switch S2, the third switch S3 and the fourth switch S4 in the A-port circuit are all turned off, and the circuit operates in passive rectification mode through the body diode.

[0162] The eleventh switch S11, the fourteenth switch S14, the sixth switch S6, the seventh switch S7, and the tenth switch S10 are simultaneously turned on, with the same on-time DT. S ;

[0163] The twelfth switch S12, the thirteenth switch S13, the fifth switch S5, the eighth switch S8, and the ninth switch S9 are simultaneously turned on, with the same on-time DT. S ;

[0164] When D>0.5, the first switch S1, the second switch S2, the third switch S3 and the fourth switch S4 in the A port circuit work in PWM mode, and the duty cycle of each switch is 1-D.

[0165] The first switch S1 and the fourth switch S4 are turned on simultaneously;

[0166] The second switch S2 and the third switch S3 are turned on simultaneously;

[0167] The second switch S2 is 180° out of phase with the first switch S1.

[0168] The conduction phase of the first switch S1 leads the fifth switch S5 by 0° to 150°;

[0169] The thirteenth switch S13 and the eleventh switch S11 are complementary in conduction.

[0170] The fourteenth switch S14 and the twelfth switch S12 are complementary in conduction;

[0171] The eleventh switch S11 and the twelfth switch S12 are 180° out of phase.

[0172] Better, such as Figure 7 As shown, the duty cycle D of the eleventh switch S11 and the twelfth switch S12 in the C-port circuit is jointly determined by the C-port current control loop and the B-port voltage control loop.

[0173] When the voltage at port B reaches the target voltage at port B, the second switch K2 is turned on.

[0174] Better, such as Figure 7 As shown, the conduction phase Phi of the second switch S2 and the first switch S1 leads or lags the fifth switch S5 by an angle determined by the A-port voltage control loop (based on the target voltage of the A-port).

[0175] When the voltage at port A reaches the target voltage at port A, the first switch K1 is turned on.

[0176] The reverse pre-charge control method for the on-board three-port DC-DC converter in Example 5 uses pre-charge mode 1 to realize the low-voltage battery BAT.LV When energy is simultaneously transferred to ports A and B, the eleventh switch S11, twelfth switch S12, thirteenth switch S13, and fourteenth switch S14 of the C port circuit operate in PWM (Pulse Width Modulation) mode. The duty cycle of the eleventh switch S11 and twelfth switch S12 is D, and the duty cycle of the thirteenth switch S13 and fourteenth switch S14 maintains a certain logical relationship with that of the eleventh switch S11 and twelfth switch S12. The fifth switch S5 in the B port circuit... The sixth switch S6, the seventh switch S7, the eighth switch S8, the ninth switch S9, and the tenth switch S10 operate in PWM mode for synchronous rectification, and their duty cycles maintain a certain logical relationship with the eleventh switch S11 and the twelfth switch S12; the first switch S1, the second switch S2, the third switch S3, and the fourth switch S4 of the A-port circuit operate in PWM mode, and their duty cycles and phases maintain a certain logical relationship with the fifth switch S5 and the sixth switch S6.

[0177] Example 6

[0178] The reverse pre-charge control method for an on-board three-port DC-DC converter based on Embodiment 3, such as Figure 6 As shown, the on-board three-port DC-DC converter is operated in pre-charge mode 2 to achieve low-voltage battery BAT. LV When energy is transferred only to port B:

[0179] Disconnect the second switch K2;

[0180] In the C-port circuit, the eleventh switch S11 and the twelfth switch S12 are complementary in conducting, and their conduction durations are both DT. S The duty cycle is D;

[0181] The thirteenth switch S13 and the fourteenth switch S14 are complementary and conduct.

[0182] When the thirteenth switch S13 is turned on, the eleventh switch S11 is turned off and the twelfth switch S12 is turned on.

[0183] When the fourteenth switch S14 is turned on, the eleventh switch S11 is turned on and the twelfth switch S12 is turned off.

[0184] When the thirteenth switch S13 is turned on, the eleventh switch S11 is turned off and the twelfth switch S12 is turned on.

[0185] When the fourteenth switch S14 is turned on, the eleventh switch S11 is turned on and the twelfth switch S12 is turned off.

[0186] As the voltage between the two ends of port B of the high-voltage battery gradually increases, the duty cycle D of the eleventh switch S11 and the twelfth switch S12 gradually increases from 0.

[0187] In the B-port circuit, the fifth switch S5, the sixth switch S6, the seventh switch S7, the eighth switch S8, the ninth switch S9, and the tenth switch S10 are all turned off.

[0188] In the A-port circuit, the first switch S1 and the third switch S3 remain off, while the second switch S2 and the fourth switch S4 remain off and are normally on.

[0189] Preferably, the second switch K2 is turned on when the voltage at port B reaches the target voltage at port B.

[0190] The reverse pre-charge control method for the on-board three-port DC-DC converter in Example 6 uses pre-charge mode 2 to realize the low-voltage battery BAT. LV When energy is only transferred to port B, the eleventh switch S11, twelfth switch S12, thirteenth switch S13, and fourteenth switch S14 of the C port circuit operate in PWM (Pulse Width Modulation) mode. The duty cycle of the eleventh switch S11 and the twelfth switch S12 is D, and the duty cycle of the thirteenth switch S13 and the fourteenth switch S14 maintains a certain logical relationship with that of the eleventh switch S11 and the twelfth switch S12. All switches in the B port circuit are not turned on. In the A port circuit, the first switch S1 and the third switch S3 remain off, while the second switch S2 and the fourth switch S4 remain off and are normally on.

[0191] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A reverse pre-charge control method for an on-board three-port DC-DC converter, wherein the on-board three-port converter includes an A-port circuit, a B-port circuit, and a C-port circuit; the B-port circuit transmits energy to the A-port circuit and the C-port circuit through a transformer; the A-port of the A-port circuit is used to connect to the PFC bus of the on-board charger, and the B-port of the B-port circuit is used to connect to the high-voltage battery (BAT). HV The C port of the C-port circuit is used to connect a low-voltage battery (BAT). LV ); characterized in that, A bus capacitor is connected between the two ends of port A (C) BUS A high-voltage electrical equipment capacitor (C) is connected in parallel between the two ends of port B. HV ); Bus capacitor (C) BUS A first switch (K1) is connected in series in the circuit to the mains power supply. High voltage battery (BAT) HV The capacitor (C) is connected in parallel to the high-voltage electrical equipment capacitor after being connected in series with the second switch (K2). HV Both ends; The C-port circuit, B-port circuit, and A-port circuit can all achieve bidirectional power transmission. By controlling the turn-on and turn-off timing of the switching transistors in the A-port, B-port, and C-port circuits, the on-board three-port DC-DC converter is made to operate in pre-charge mode 1 to realize the operation of the low-voltage battery (BAT). LV Energy can be transferred to both ports A and B simultaneously, or the onboard three-port DC-DC converter can be put into pre-charge mode 2 to achieve low-voltage battery (BAT) LV Energy is transferred only to port B; the following steps are included: S1. Connect the charging gun to wake up the vehicle's three-port DC-DC converter; S2. Operate the onboard three-port DC-DC converter in pre-charge mode 1, low-voltage battery (BAT) LV Energy is transferred simultaneously to ports A and B; S3. When V BUS -V AC_PK > V TH_BUS V BUS Bus capacitor (C) BUS The voltage across the bus at both ends, V AC_PK V represents the peak AC input voltage of the on-board charger. TH_BUS If the bus threshold voltage is reached, then the first switch (K1) is closed, and the gate drive signals of each switch in the A-port circuit are stopped, proceeding to step S4; when V BUS -V AC_PK ≤ V TH_BUS Then proceed to step S2; S4. Operate the onboard three-port DC-DC converter in pre-charge mode 2, low-voltage battery (BAT) LV Energy is transferred only to port B; S5. When V HV –V HV_CMD > V TH_HV V HV For high-voltage electrical equipment capacitors (C) HV Voltage across the terminals, V HV_CMD For the target high pressure, V TH_HV If the voltage is the high-voltage threshold voltage, then close the second switch (K2) and proceed to step S6; when V HV –V HV_CMD ≤ V TH_HV Then proceed to step S4; S6. End pre-charging.

2. The reverse pre-charge control method for an on-board three-port DC-DC converter according to claim 1, characterized in that, The C-port circuit adopts a full-wave rectification structure, a full-bridge rectification structure, or a current-doubler rectification structure.

3. The reverse pre-charge control method for an on-board three-port DC-DC converter according to claim 1, characterized in that, The mains power is either single-phase AC or three-phase AC.

4. The reverse pre-charge control method for an on-board three-port DC-DC converter according to claim 1, characterized in that, The first switch (K1) and the second switch (K2) are relay switches.

5. The reverse pre-charge control method for an on-board three-port DC-DC converter according to claim 4, characterized in that, In step S3, when V BUS -V AC_PK ≤ V TH_BUS If the duration is less than or equal to the first set time, proceed to step S2; if the duration is greater than the first set time, enter a fault state.

6. The reverse pre-charge control method for an on-board three-port DC-DC converter according to claim 4, characterized in that, In step S5, when V HV –V HV_CMD ≤ V TH_HV If the duration is less than or equal to the second set time, proceed to step S4; if the duration is greater than the second set time, enter a fault state.

7. The reverse pre-charge control method for an on-board three-port DC-DC converter according to claim 1, characterized in that, The vehicle-mounted three-port converter includes a first transformer (T1) and a second transformer (T2), which are independent of each other. The first transformer (T1) includes a first magnetic core, an A-port side winding (n1) and a first B-port side winding (n2). The second transformer (T2) includes a second magnetic core, a second B-port side winding (n3), and a C-port side winding; The C-port side winding includes a C-port side first winding (n4) and a C-port side second winding (n5); The A-port circuit includes a first switch (S1), a second switch (S2), a third switch (S3), and a fourth switch (S4); the first switch (S1) and the second switch (S2) form the first bridge arm, and the third switch (S3) and the fourth switch (S4) form the second bridge arm. The midpoints of its first and second bridge arms are respectively connected to the two ends of the winding (n1) on the A-port side of the first transformer (T1), and the two ends of its first and second bridge arms serve as the A-port. The B-port circuit includes a fifth switch (S5), a sixth switch (S6), a seventh switch (S7), an eighth switch (S8), a ninth switch (S9), and a tenth switch (S10); the fifth switch (S5) and the sixth switch (S6) form the third bridge arm; the seventh switch (S7) and the eighth switch (S8) form the fourth bridge arm; the ninth switch (S9) and the tenth switch (S10) form the fifth bridge arm; the two ends of the third bridge arm, the fourth bridge arm, and the fifth bridge arm serve as B-ports; the two ends of the first B-port side winding (n2) are respectively connected to the midpoints of the third bridge arm and the fourth bridge arm; the two ends of the second B-port side winding (n3) are respectively connected to the midpoints of the fourth bridge arm and the fifth bridge arm. The C-port circuit includes an eleventh switch (S11), a twelfth switch (S12), a thirteenth switch (S13), and a fourteenth switch (S14). The source and drain terminals of the twelfth switching transistor (S12) are connected to the same-name terminal of the first winding (n4) on the C-port side and the working low-voltage negative terminal (LV-), respectively. The source and drain terminals of the eleventh switching transistor (S11) are connected to the opposite-name terminal of the second winding (n5) on the C-port side and the negative terminal of the working low voltage (LV-), respectively. One end of the source and drain of the fourteenth switch (S14) is connected to the same-name terminal of the first winding (n4) on the C port side, and the other end is connected to the working low voltage negative terminal (LV-) via the second clamping capacitor (C2). One end of the source and drain of the thirteenth switch (S13) is connected to the opposite terminal of the second winding (n5) on the C port side, and the other end is connected to the working low voltage negative terminal (LV-) via the first clamping capacitor (C1). One end of the filter inductor (Lo) is connected to the low-voltage positive terminal (LV+), and the other end is connected to the opposite-name terminal of the first winding (n4) on the C port side and the same-name terminal of the second winding (n5) on the C port side.

8. The reverse pre-charge control method for an on-board three-port DC-DC converter according to claim 7, characterized in that, The switching frequency of the transistors in the A-port circuit, B-port circuit, and C-port circuit is the same: fs. To enable the onboard three-port DC-DC converter to operate in pre-charge mode 1, low-voltage battery (BAT) is achieved. LV When transferring energy to both port A and port B simultaneously, the first switch (K1) and the second switch (K2) are disconnected: In the C-port circuit, the eleventh switch (S11) and the twelfth switch (S12) are complementary in conducting, and their conduction duration is the same as DT. S The duty cycle is D; The thirteenth switch (S13) and the fourteenth switch (S14) are complementary in conducting; When the thirteenth switch (S13) is turned on, the eleventh switch (S11) is turned off and the twelfth switch (S12) is turned on. When the fourteenth switch (S14) is turned on, the eleventh switch (S11) is turned on and the twelfth switch (S12) is turned off. In the B-port circuit, the switching sequence of the fifth switch (S5), the eighth switch (S8), and the ninth switch (S9) is the same as that of the thirteenth switch (S13). The switching sequence of the sixth switch (S6), the seventh switch (S7), and the tenth switch (S10) is the same as that of the fourteenth switch (S14); As the voltage between the two ends of the B port of the high-voltage battery gradually increases, the duty cycle D of the eleventh switch (S11) and the twelfth switch (S12) gradually increases from 0. When D≤0.5, the first switch (S1), the second switch (S2), the third switch (S3) and the fourth switch (S4) in the A-port circuit are all turned off, and the circuit operates in passive rectification mode through the body diode. The eleventh switch (S11), fourteenth switch (S14), sixth switch (S6), seventh switch (S7), and tenth switch (S10) are simultaneously turned on, with the same on-time DT. S ; The twelfth switch (S12), the thirteenth switch (S13), the fifth switch (S5), the eighth switch (S8), and the ninth switch (S9) are simultaneously turned on, with the same on-time being DT. S ; When D>0.5, the first switch (S1), the second switch (S2), the third switch (S3), and the fourth switch (S4) in the A-port circuit operate in PWM mode, and their duty cycles are all 1-D. The first switch (S1) and the fourth switch (S4) are turned on simultaneously; The second switch (S2) and the third switch (S3) are turned on simultaneously; The second switch (S2) is 180° out of phase with the first switch (S1); The conduction phase of the first switch (S1) leads the fifth switch (S5) by 0° to 150°; The thirteenth switch (S13) and the eleventh switch (S11) are complementary in conduction; The fourteenth switch (S14) and the twelfth switch (S12) are complementary in conduction; The eleventh switch (S11) and the twelfth switch (S12) are 180° out of phase.

9. The reverse pre-charge control method for an on-board three-port DC-DC converter according to claim 8, characterized in that, The duty cycle D of the eleventh switch (S11) and the twelfth switch (S12) of the C-port circuit is jointly determined by the C-port current control loop and the B-port voltage control loop. When the voltage at port B reaches the target voltage at port B, the second switch (K2) is turned on.

10. The reverse pre-charge control method for an on-board three-port DC-DC converter according to claim 8, characterized in that, The conduction phases of the second switch (S2) and the first switch (S1) lead or lag the fifth switch (S5) by an angle determined by the A-port voltage control loop. When the voltage at port A reaches the target voltage at port A, the first switch (K1) is turned on.

11. The reverse pre-charge control method for an on-board three-port DC-DC converter according to claim 7, characterized in that, This enables the onboard three-port DC-DC converter to operate in pre-charge mode 2 to achieve low-voltage battery (BAT) operation. LV When energy is transferred only to port B: Turn off the second switch (K2); In the C-port circuit, the eleventh switch (S11) and the twelfth switch (S12) are complementary in conducting, and their conduction duration is the same as DT. S The duty cycle is D; The thirteenth switch (S13) and the fourteenth switch (S14) are complementary in conducting; When the thirteenth switch (S13) is turned on, the eleventh switch (S11) is turned off and the twelfth switch (S12) is turned on. When the fourteenth switch (S14) is turned on, the eleventh switch (S11) is turned on and the twelfth switch (S12) is turned off. When the thirteenth switch (S13) is turned on, the eleventh switch (S11) is turned off and the twelfth switch (S12) is turned on. When the fourteenth switch (S14) is turned on, the eleventh switch (S11) is turned on and the twelfth switch (S12) is turned off. As the voltage between the two ends of the B port of the high-voltage battery gradually increases, the duty cycle D of the eleventh switch (S11) and the twelfth switch (S12) gradually increases from 0. In the B-port circuit, the fifth switch (S5), the sixth switch (S6), the seventh switch (S7), the eighth switch (S8), the ninth switch (S9), and the tenth switch (S10) are all turned off; In the A-port circuit, the first switch (S1) and the third switch (S3) remain off, while the second switch (S2) and the fourth switch (S4) remain off and are normally on.

12. The reverse pre-charge control method for an on-board three-port DC-DC converter according to claim 11, characterized in that, When the voltage at port B reaches the target voltage at port B, the second switch (K2) is turned on.

13. The reverse pre-charge control method for an on-board three-port DC-DC converter according to claim 7, characterized in that, The positive terminal of the first diode D1 is connected to the opposite terminal of the second winding (n5) on the C port side, and the negative terminal is connected to the working low voltage negative terminal (LV-) via the first clamping capacitor (C1). The positive terminal of the second diode D2 is connected to the same terminal of the first winding (n4) on the C port side, and the negative terminal is connected to the working low voltage negative terminal (LV-) via the second clamping capacitor (C2).

14. The reverse pre-charge control method for an on-board three-port DC-DC converter according to claim 7, characterized in that, The eleventh switch (S11), twelfth switch (S12), thirteenth switch (S13) and fourteenth switch (S14) are all insulated gate enhancement type NMOS transistors; The source terminal of the eleventh switch (S11), the source terminal of the twelfth switch (S12), the drain terminal of the thirteenth switch (S13), and the drain terminal of the fourteenth switch (S14) are all connected to the low-voltage negative terminal (LV-).

15. The reverse pre-charge control method for an on-board three-port DC-DC converter according to claim 7, characterized in that, The C-port circuit also includes a filter capacitor (Co). The two ends of the filter capacitor (Co) are connected to the positive terminal (LV+) and the negative terminal (LV-) of the low working voltage, respectively.

16. The reverse pre-charge control method for an on-board three-port DC-DC converter according to claim 7, characterized in that, The A-port circuit also includes a resonant inductor (Lr), a resonant capacitor (Cr), and a magnetizing inductor (Lm). The two ends of the resonant inductor (Lr) are respectively connected to the midpoint of the first bridge arm and the corresponding terminals of the winding (n1) on the A port side; The two ends of the resonant capacitor (Cr) are respectively connected to the opposite ends of the winding (n1) on the A port side at the midpoint of the second bridge arm. The excitation inductor (Lm) is connected at both ends to the midpoint of the second bridge arm and the two ends of the winding (n1) on the A port side, respectively.

17. The reverse pre-charge control method for an on-board three-port DC-DC converter according to claim 7, characterized in that, The B-port circuit also includes leakage inductance (Ls); The two ends of the leakage inductance (Ls) are respectively connected to the midpoint of the fifth bridge arm and the opposite end of the second B port side winding (n3).

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