DCDC converter, vehicle charging device, system and vehicle

Abstract

The present application provides a DCDC converter, an on-board charging device, a system and a vehicle, and relates to the field of on-board charging technology. The DCDC converter includes: a first DC power supply terminal, a main transformer, a first part of the circuit located on the secondary side of the main transformer, a second part of the circuit located on the primary side of the main transformer and a second DC power supply terminal; the first DC power supply terminal is used to connect the low-voltage battery of the on-board charging system, and the second DC power supply terminal is used to connect the on-board charger of the on-board charging system. Compared with the prior art, the pre-charging circuit on the OBC and high-voltage battery side can be omitted, which not only improves the power density and safety of the OBC, but also reduces the cost of the OBC and the entire vehicle.

Description

Technical Field

[0001] The present application relates to the field of vehicle-mounted charging technology, and in particular to a DCDC converter, a vehicle-mounted charging device, a system and a vehicle. Background Art

[0002] During the charging process of the on-board charger, if the charging voltage is too high, the charging current will be very large, which may damage the busbar and the capacitor. Therefore, in the prior art, in order to limit the charging current, a pre-charging process is usually added to the on-board charger to achieve the purpose of protecting the circuit.

[0003] Since the busbar of the on-board charger (OBC) is equipped with a large-capacitance electrolytic capacitor to achieve the voltage stabilization function, the traditional pre-charging circuit usually pre-charges the busbar capacitor before the on-board charger is started to suppress the input pulse current. The pre-charging circuit is composed of a relay and a resistor; or a set of pre-charging circuits is added to the busbar on the high-voltage battery side to prevent surge current.

[0004] However, although the additional pre-charging circuit ensures the circuit safety, it causes problems such as a larger size and higher cost of the on-board charger. Summary of the invention

[0005] The purpose of this application is to provide a DCDC converter, a vehicle charging device, a system and a vehicle to address the deficiencies in the above-mentioned prior art, which can eliminate the pre-charging circuit on the OBC and the high-voltage battery side, thereby not only improving the power density and safety of the OBC, but also reducing the cost of the OBC and the entire vehicle.

[0006] To achieve the above purpose, the technical solution adopted in the embodiment of the present application is as follows:

[0007] In a first aspect, an embodiment of the present application provides a DC-DC DCDC converter for a vehicle charging system, comprising:

[0008] A first DC power supply terminal, a main transformer, a first circuit located on a secondary side of the main transformer, a second circuit located on a primary side of the main transformer, and a second DC power supply terminal;

[0009] The first DC power supply end is used to connect to the low-voltage battery of the vehicle charging system, and the second DC power supply end is used to connect to the vehicle charger of the vehicle charging system;

[0010] The first circuit includes: a slave transformer and a secondary switch tube, one end of the secondary inductor of the slave transformer is connected to the positive electrode of the first DC power supply terminal, and the other end of the secondary inductor of the slave transformer is connected to the secondary inductor of the main transformer; the other end of the secondary inductor of the slave transformer is also connected to the negative electrode of the first DC power supply terminal through the secondary switch tube;

[0011] One end of the primary inductor of the slave transformer is grounded, and the other end of the primary inductor of the slave transformer is connected to the positive electrode of the second DC power supply terminal through a diode;

[0012] The second circuit includes: a primary capacitor and a primary switch tube, one end of the primary inductor of the main transformer is connected to the positive and negative electrodes of the second DC power supply terminal respectively through the two primary switch tubes; the other end of the primary inductor of the main transformer is connected to the positive and negative electrodes of the second DC power supply terminal respectively through the two primary capacitors.

[0013] Further, the slave transformer includes: a first slave transformer and a second slave transformer; the secondary side switch tube includes: a first secondary side switch tube and a second secondary side switch tube;

[0014] One end of the secondary inductance of the first slave transformer and the second slave transformer is connected to the positive electrode of the first DC power supply terminal, the other end of the secondary inductance of the first slave transformer is connected to one end of the secondary inductance of the main transformer, and the other end of the secondary inductance of the second slave transformer is connected to the other end of the secondary inductance of the main transformer;

[0015] The other end of the secondary inductor of the first slave transformer is connected to the negative electrode of the first DC power supply terminal through the first secondary switch tube; the other end of the secondary inductor of the second slave transformer is connected to the negative electrode of the first DC power supply terminal through the second secondary switch tube;

[0016] One end of the primary inductance of the first slave transformer and the second slave transformer is grounded, and the other end of the primary inductance of the first slave transformer and the second slave transformer is connected to the positive electrode of the second DC power supply terminal through a diode respectively.

[0017] Further, the slave transformer is a transformer; the secondary side switch tube includes: a third secondary side switch tube and a fourth secondary side switch tube;

[0018] The other end of the secondary inductor of the slave transformer is connected to one end of the secondary inductor of the main transformer through the third secondary switch tube; the other end of the secondary inductor of the slave transformer is also connected to the other end of the secondary inductor of the main transformer through the fourth secondary switch tube;

[0019] The middle position of the secondary inductor of the main transformer is connected to the negative electrode of the first DC power supply end.

[0020] Furthermore, the first DC power supply terminal and the second DC power supply terminal are respectively connected in parallel with a capacitor.

[0021] In a second aspect, another embodiment of the present application provides a vehicle-mounted charging device, comprising: an AC input terminal, an on-board charger, a first DC-DC DCDC converter, a high-voltage battery, and a low-voltage battery;

[0022] Wherein, the AC input terminal is connected to the high-voltage battery through the on-board charger;

[0023] The first DCDC converter is any one of the converters described in the first aspect above;

[0024] The first DC power supply end of the first DCDC converter is connected to the low-voltage battery, and the second DC power supply end of the first DCDC converter is connected to the on-board charger.

[0025] Furthermore, the on-board charger includes: a circuit module and a second DCDC converter; the AC input end is connected to one end of the second DCDC converter through the circuit module, and the other end of the second DCDC converter is connected to the high-voltage battery;

[0026] The second DC power supply end is connected to one end of the second DCDC converter, or to the other end of the second DCDC converter.

[0027] Furthermore, the circuit module is: a rectifier circuit or a correction circuit; the second DCDC converter is a bidirectional isolated DCDC converter or a unidirectional isolated DCDC converter.

[0028] In a third aspect, another embodiment of the present application provides a vehicle-mounted charging system, including: a vehicle-mounted charging device and a control circuit; wherein:

[0029] The vehicle-mounted charging device comprises: an AC input terminal, a vehicle-mounted charger, a DCDC converter, a high-voltage battery and a low-voltage battery;

[0030] The control circuit is electrically connected to the vehicle-mounted charging device and is used to control the working state of the vehicle-mounted charging device.

[0031] Furthermore, the on-board charger includes: a circuit module and a second DCDC converter; the AC input end is connected to one end of the second DCDC converter through the circuit module, and the other end of the second DCDC converter is connected to the high-voltage battery;

[0032] The second DC power supply end is connected to one end of the second DCDC converter, or to the other end of the second DCDC converter.

[0033] In a fourth aspect, another embodiment of the present application provides a vehicle, comprising the on-board charging system described in the third aspect above.

[0034] The beneficial effect of the present application is that: by using the DCDC converter for the on-board charging system provided by the present application, during reverse charging, a flyback circuit can be formed by a slave transformer, a secondary switch tube and a diode connected to the primary inductance of the slave transformer, and the flyback circuit is used to control the secondary switch tube, so that when the secondary switch tube is closed, the low-voltage battery is charged with the primary inductance of the slave transformer, that is, the excitation inductance, by connecting the first DC power supply end of the low-voltage battery; when the secondary switch tube is disconnected, the energy of the excitation inductance of the slave transformer can be transmitted to the primary capacitor to realize the reverse flow of energy, that is, to realize the reverse charging of the low-voltage battery to the on-board charger, thereby realizing the pre-charging function of the low-voltage battery to the OBC bus and the high-voltage battery side of the whole vehicle, thereby eliminating the pre-charging circuit of the OBC and the high-voltage battery side, while improving the power density and safety of the OBC, also reducing the cost of the OBC and the whole vehicle. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0036] Figure 1 A schematic diagram of the structure of a DCDC converter provided in one embodiment of the present application;

[0037] Figure 2 A schematic diagram of the structure of a DCDC converter provided in another embodiment of the present application;

[0038] Figure 3 A schematic diagram of the structure of a vehicle-mounted charging device provided in one embodiment of the present application;

[0039] Figure 4 A schematic diagram of the structure of a vehicle-mounted charging device provided in another embodiment of the present application;

[0040] Figure 5 A schematic diagram of the structure of a vehicle-mounted charging device provided in another embodiment of the present application;

[0041] Figure 6 A schematic diagram of the structure of a vehicle-mounted charging device provided in another embodiment of the present application;

[0042] Figure 7 A schematic diagram of the structure of a vehicle-mounted charging device provided in another embodiment of the present application;

[0043] Figure 8 A schematic diagram of the structure of a vehicle-mounted charging device provided in another embodiment of the present application;

[0044] Fig. 9 A schematic diagram of the structure of a vehicle-mounted charging device provided in another embodiment of the present application;

[0045] Fig.10 A schematic diagram of the structure of a vehicle-mounted charging device provided in another embodiment of the present application;

[0046] Fig.11 A schematic diagram of the structure of a vehicle charging system provided in one embodiment of the present application.

[0047] Description of the drawings: 100-DCDC converter; 110-first circuit; 120-second circuit; 130-main transformer; 140-first DC power supply terminal; 150-second DC power supply terminal; 200-on-board charging device; 210-AC input terminal; 220-on-board charger; 221-circuit module; 221a-correction circuit; 221b-rectifier circuit; 222-second DCDC converter; 222a-bidirectional isolated DCDC converter; 222b-unidirectional isolated DCDC converter; 230-first DCDC converter; 240-low-voltage battery; 250-high-voltage battery; 300-on-board charging system; 310-control circuit. DETAILED DESCRIPTION

[0048] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments.

[0049] Figure 1 A schematic diagram of the structure of a DCDC converter provided in one embodiment of the present application is shown in FIG. Figure 1 As shown, the DCDC converter 100 can be a high-power DCDC converter, which may include: a first DC power supply terminal 140, a main transformer 130, a first circuit 110 located on the secondary side of the main transformer 130, a second circuit 120 located on the primary side of the main transformer 130, and a second DC power supply terminal 150.

[0050] The first DC power supply terminal 140 is used to connect to a low-voltage battery of the vehicle charging system, and the second DC power supply terminal 150 is used to connect to an on-board charger of the vehicle charging system.

[0051] The first circuit 110 includes: a slave transformer and a secondary switch tube, one end of the secondary inductor of the slave transformer is connected to the positive pole of the first DC power supply terminal 140, and the other end of the secondary inductor of the slave transformer is connected to the secondary inductor of the main transformer 130; the other end of the secondary inductor of the slave transformer is also connected to the negative pole of the first DC power supply terminal 140 through the secondary switch tube.

[0052] One end of the primary inductor of the transformer is grounded, and the other end of the primary inductor of the transformer is connected to the positive electrode of the second DC power supply terminal 150 through a diode.

[0053] The second circuit 120 includes: a primary capacitor and a primary switch tube. One end of the primary inductance of the main transformer 130 is connected to the positive and negative electrodes of the second DC power supply terminal 150 respectively through two primary switch tubes; the other end of the primary inductance of the main transformer 130 is connected to the positive and negative electrodes of the second DC power supply terminal 150 respectively through two primary capacitors.

[0054] Above Figure 1 In the DCDC converter 100 shown, the primary-to-secondary coil ratio of the main transformer 130 may be n2:1. The slave transformer may include one transformer, or two transformers, or multiple transformers. Regardless of the number of transformers, the primary-to-secondary coil ratio of the slave transformer may be n1:1. Where n1 may be different from n2.

[0055] The primary switch tube and the secondary switch tube can both be metal oxide semiconductor (MOS) field effect transistors. Of course, they can also be other types of switch tubes, which is not limited in the present application.

[0056] The DCDC converter provided in this embodiment, when forward charging, is composed of a primary capacitor, a primary switch tube, a main transformer, a secondary switch tube, and an excitation inductor of a slave transformer to form a primary half-bridge of a main transformer and a secondary current doubler rectification circuit. One end is connected to the second DC power supply end of the on-board charger and the other end is connected to the first DC power supply end of the low-voltage battery, so that the on-board charger can forward charge the low-voltage battery.

[0057] At the same time, during reverse charging, a flyback circuit can be formed by a slave transformer, a secondary switch tube and a diode connected to the primary inductor of the slave transformer. The flyback circuit is used to control the secondary switch tube so that when the secondary switch tube is closed, the low-voltage battery charges the excitation inductance of the slave transformer through the first DC power supply end of the connected low-voltage battery; when the secondary switch tube is disconnected, the energy of the excitation inductance of the slave transformer is transmitted to the primary capacitor to realize the reverse flow of energy, that is, the reverse charging of the low-voltage battery to the on-board charger is realized, thereby realizing the pre-charging function of the low-voltage battery to the OBC bus and the high-voltage battery side of the whole vehicle, thereby eliminating the pre-charging circuit between the OBC and the high-voltage battery side, while improving the power density and safety of the OBC, it also reduces the cost of the OBC and the whole vehicle.

[0058] The following embodiments of the present application can respectively illustrate the DCDC converter provided by the present application through two slave transformers and one slave transformer implementation examples. Figure 1 is a possible example of two slave transformers.

[0059] Continue to refer to Figure 1 Optionally, the slave transformer may include: a first slave transformer T1 and a second slave transformer T2; the secondary side switch tube may include: a first secondary side switch tube SR1 and a second secondary side switch tube SR2.

[0060] Specifically, one end of the secondary inductance of the first slave transformer T1 and the second slave transformer T2 is connected to the positive electrode of the first DC power supply end, the other end of the secondary inductance of the first slave transformer T1 is connected to one end of the secondary inductance of the main transformer T3, and the other end of the secondary inductance of the second slave transformer T2 is connected to the other end of the secondary inductance of the main transformer T3.

[0061] The other end of the secondary inductor of the first slave transformer T1 is connected to the negative electrode of the first DC power supply terminal through the first secondary switch tube SR1; the other end of the secondary inductor of the second slave transformer T2 is connected to the negative electrode of the first DC power supply terminal through the second secondary switch tube SR2.

[0062] One end of the primary inductance of the first slave transformer T1 and the second slave transformer T2 is grounded, and the other end of the primary inductance of the first slave transformer T1 and the second slave transformer T2 is connected to the positive electrode of the second DC power supply through diodes D1 and D2 respectively.

[0063] In this embodiment, when the DCDC converter is forward charged, the primary capacitors C1 and C2, the primary switch tube P1, the main transformer T3, the first secondary switch tube SR1, the second secondary switch tube SR2, the excitation inductance of the first slave transformer T1, and the excitation inductance of the second slave transformer T2 constitute the main transformer primary half-bridge and secondary current doubler rectification circuit, and the on-board charger is connected to the second DC power supply end of the on-board charger and the first DC power supply end of the low-voltage battery to realize the forward charging of the low-voltage battery by the on-board charger.

[0064] At the same time, when the DCDC converter 100 in this embodiment is reversely charged, the first slave transformer T1, the second slave transformer T2, the first secondary switch tube SR1, the second secondary switch tube SR2, the diode D1 connected to the primary inductor of the first slave transformer T1, and the diode D2 connected to the primary inductor of the second slave transformer T2 form a flyback circuit, and the flyback circuit is used to control the first secondary switch tube SR1 and the second secondary switch tube SR2, so that when the first secondary switch tube SR1 and the second secondary switch tube SR2 are closed, the low-voltage battery is connected to the first DC power supply terminal of the low-voltage battery, so that the low-voltage battery is the first slave transformer. The primary inductance of the transformer T1 and the primary inductance of the second slave transformer T2 are charged; when the first secondary switch tube SR1 and the second secondary switch tube SR2 are both disconnected, the energy of the excitation inductance of the first slave transformer T1 and the excitation inductance of the second slave transformer T2 can be transmitted to the primary capacitors C1 and C2, realizing the reverse flow of energy, and realizing the reverse charging of the low-voltage battery to the on-board charger, thereby realizing the pre-charging function of the low-voltage battery to the OBC bus and the high-voltage battery side of the whole vehicle, thereby eliminating the pre-charging circuit of the OBC and the high-voltage battery side, while improving the power density and safety of the OBC, it also reduces the cost of the OBC and the whole vehicle.

[0065] In another embodiment, the present application also provides an implementation example of a DCDC converter including a slave transformer. Figure 2 FIG. 1 is a schematic diagram of the structure of a DCDC converter provided by another embodiment of the present application. Figure 2 As shown, the slave transformer in the DCDC converter 100 may include a slave transformer T4; the secondary side switch tube may include: a third secondary side switch tube SR3 and a fourth secondary side switch tube SR4.

[0066] The other end of the secondary inductor of the slave transformer T4 is connected to one end of the secondary inductor of the main transformer T3 through the third secondary switch tube SR3; the other end of the secondary inductor of the slave transformer T4 is also connected to the other end of the secondary inductor of the main transformer T3 through the fourth secondary switch tube SR4.

[0067] The middle position of the secondary inductor of the main transformer T3 is connected to the negative electrode of the first DC power supply terminal.

[0068] During forward charging, the primary capacitors C1 and C2, the primary switch tubes P1 and P2, the main transformer T3, the third secondary switch tube SR3, the fourth secondary switch tube SR4, and the excitation inductance of the slave transformer T4 constitute a main transformer primary half-bridge and a secondary current doubler rectification circuit, and the on-board charger can forward charge the low-voltage battery by connecting the second DC power supply terminal of the on-board charger and the first DC power supply terminal of the low-voltage battery.

[0069] At the same time, during reverse charging, a flyback circuit can be formed by the slave transformer T4, the third secondary switch tube SR3, the fourth secondary switch tube SR4 and the diode D3 connected to the primary inductor of the slave transformer T4. The flyback circuit is used to control the third secondary switch tube SR3 and the fourth secondary switch tube SR4, so that when the third secondary switch tube SR3 and the fourth secondary switch tube SR4 are closed, the low-voltage battery charges the primary inductor, i.e., the excitation inductor, of the slave transformer T4 by connecting the first DC power supply terminal of the low-voltage battery; when the third secondary switch tube SR3 and the fourth secondary switch tube SR4 are disconnected, the energy of the excitation inductor of the slave transformer T4 can be transmitted to the primary capacitors C1 and C2, realizing the reverse flow of energy, realizing the reverse charging from the low-voltage battery to the on-board charger, thereby realizing the pre-charging function of the low-voltage battery to the OBC bus and the high-voltage battery side of the whole vehicle, thereby eliminating the pre-charging circuit between the OBC and the high-voltage battery side, while improving the power density and safety of the OBC, it also reduces the cost of the OBC and the whole vehicle.

[0070] In addition, no matter which type of DCDC converter 100 is used, a capacitor is connected in parallel to the first DC power supply terminal and the second DC power supply terminal respectively, so as to achieve filtering and voltage stabilization of the converter input and output.

[0071] Figure 3 A schematic diagram of the structure of a vehicle-mounted charging device 200 provided in an embodiment of the present application is shown in FIG. Figure 3 As shown, the device includes: an AC input terminal 210 , an on-board charger 220 , a first DCDC converter 230 , a high-voltage battery 250 and a low-voltage battery 240 .

[0072] The AC input terminal 210 is connected to the high voltage battery 250 via the vehicle charger 220. Optionally, the first DCDC converter 230 can be Figure 1 or Figure 2 Any DCDC converter 100 in the embodiment is not limited in any way.

[0073] Specifically, a first DC power supply terminal of the first DCDC converter 230 is connected to the low voltage battery 240 , and a second DC power supply terminal of the first DCDC converter 230 is connected to the onboard charger 220 .

[0074] The first DCDC converter in the on-board charging device can form a flyback circuit by a slave transformer, a secondary switch tube and a diode connected to the primary inductance of the slave transformer during reverse charging. The flyback circuit is used to control the secondary switch tube so that when the secondary switch tube is closed, the low-voltage battery is charged with the primary inductance of the slave transformer, that is, the excitation inductance, by connecting the first DC power supply end of the low-voltage battery; when the secondary switch tube is disconnected, the energy of the excitation inductance of the slave transformer can be transmitted to the primary capacitor to realize the reverse flow of energy, thereby realizing the reverse charging of the low-voltage battery to the on-board charger, thereby realizing the pre-charging function of the low-voltage battery to the OBC bus and the high-voltage battery side of the whole vehicle, thereby eliminating the pre-charging circuit between the OBC and the high-voltage battery side, while improving the power density and safety of the OBC, it also reduces the cost of the OBC and the whole vehicle.

[0075] Figure 4 A schematic diagram of the structure of a vehicle charging system provided in an embodiment of the present application is shown in FIG. Figure 4 As shown, the on-board charger 220 includes: a circuit module 221 and a second DCDC converter 222; the AC input end 210 is connected to one end of the second DCDC converter 222 through the circuit module 221, and the other end of the second DCDC converter 222 is connected to the high-voltage battery 250; wherein the circuit module 221 can be: a rectifier circuit or a correction circuit; the second DCDC converter 222 can be a bidirectional isolated DCDC converter or a unidirectional isolated DCDC converter.

[0076] The rectifier circuit 221b may be a bidirectional rectifier circuit; the correction circuit 221a may be a power factor correction circuit (Power Factor Correction, PFC).

[0077] Optionally, the rectifier circuit 221 b or the correction circuit 221 a and the bidirectional isolated DCDC converter 222 a or the unidirectional isolated DCDC converter 222 b may be matched arbitrarily in pairs.

[0078] For example:

[0079] (1) Figure 5 A schematic diagram of the structure of a vehicle charging system provided in another embodiment of the present application is shown in FIG. Figure 5 As shown, the vehicle charging system may include: an AC input terminal 210, a correction circuit 221a, a unidirectional isolation DCDC converter 222b, a high voltage battery 250, a first DCDC converter 230, and a low voltage battery 240. The AC input terminal 210 is connected to the correction circuit 221a, the correction circuit 221a is connected to the unidirectional isolation DCDC converter 222b, and the unidirectional isolation DCDC converter 222b is connected to the high voltage battery 250. Figure 5In the vehicle charging system shown, the vehicle charger 220 can be composed of a correction circuit 221a and a unidirectional isolated DCDC converter 222b. One end of the first DCDC converter 230 can be connected to the low-voltage battery 240, and the other end of the first DCDC converter 230 can be connected to the bus side of the vehicle charger 220, that is, the bus of the unidirectional isolated DCDC converter 222b in the vehicle charger. In this case, the reverse charging function of the first DCDC converter 230 can be used to first charge the bus of the vehicle charger 220 to the target voltage, and then turn on the unidirectional isolated DCDC converter 222b of the vehicle charger 220 to charge the output capacitor until the output voltage reaches the required value, and then control the working state of the unidirectional isolated DCDC converter 222b and the first DCDC converter 230 in the vehicle charger 220 so that the voltage is maintained at the target voltage.

[0080] (2) Figure 6 A schematic diagram of the structure of a vehicle charging system provided in another embodiment of the present application is shown in FIG. Figure 6 As shown, the vehicle charging system may include: an AC input terminal 210, a rectifier circuit 221b, a bidirectional isolated DCDC converter 222a, a high voltage battery 250, a first DCDC converter 230, and a low voltage battery 240. The AC input terminal 210 is connected to the rectifier circuit 221b, the rectifier circuit 221b is connected to the bidirectional isolated DCDC converter 222a, and the bidirectional isolated DCDC converter 222a is connected to the high voltage battery 250. Figure 6 In the vehicle charging system shown, the vehicle charger 220 can be composed of a rectifier circuit 221b and a bidirectional isolated DCDC converter 222a, one end of the first DCDC converter 230 can be connected to the low-voltage battery 240, and the other end of the first DCDC converter 230 can be connected to the bus side of the vehicle charger 220, that is, the bus of the unidirectional isolated DCDC converter 222b in the vehicle charger. In this case: the reverse charging function of the first DCDC converter 230 can be used to first charge the bus of the vehicle charger 220 to the target voltage, and then turn on the bidirectional isolated DCDC converter 222a of the vehicle charger 220 to charge the output capacitor until the output voltage reaches the required value, and then control the working state of the bidirectional isolated DCDC converter 222a and the first DCDC converter 230 in the vehicle charger 220 so that the voltage is maintained at the target voltage.

[0081] (3) Figure 7 A schematic diagram of the structure of a vehicle charging system provided in another embodiment of the present application is shown in FIG. Figure 7As shown, the vehicle charging system may include: an AC input terminal 210, a correction circuit 221a, a bidirectional isolated DCDC converter 222a, a high voltage battery 250, a first DCDC converter 230, and a low voltage battery 240. The AC input terminal 210 is connected to the correction circuit 221a, the correction circuit 221a is connected to the bidirectional isolated DCDC converter 222a, and the bidirectional isolated DCDC converter 222a is connected to the high voltage battery 250. Figure 7 In the vehicle charging system shown, the vehicle charger 220 can be composed of a correction circuit 221a and a bidirectional isolated DCDC converter 222a, one end of the first DCDC converter 230 can be connected to the low-voltage battery 240, and the other end of the first DCDC converter 230 can be connected to the bus side of the vehicle charger, that is, the bus of the unidirectional isolated DCDC converter 222b in the vehicle charger. In this case: the reverse charging function of the first DCDC converter 230 can be used to first charge the bus of the vehicle charger 220 to the target voltage, and then turn on the bidirectional isolated DCDC converter 222a of the vehicle charger 220 to charge the output capacitor until the output voltage reaches the required value, and then control the working state of the bidirectional isolated DCDC converter 222a and the first DCDC converter 230 in the vehicle charger 220 so that the voltage is maintained at the required voltage.

[0082] (4) Figure 8 A schematic diagram of the structure of a vehicle charging system provided in another embodiment of the present application is shown in FIG. Figure 8 As shown, the vehicle charging system may include: an AC input terminal 210, a correction circuit 221a, a unidirectional isolation DCDC converter 222b, a high voltage battery 250, a first DCDC converter 230, and a low voltage battery 240. The AC input terminal 210 is connected to the correction circuit 221a, the correction circuit 221a is connected to the unidirectional isolation DCDC converter 222b, and the unidirectional isolation DCDC converter 222b is connected to the high voltage battery 250. Figure 8 In the vehicle charging system shown, the vehicle charger 220 can be composed of a correction circuit 221a and a unidirectional isolation DCDC converter 222b, one end of the first DCDC converter 230 can be connected to the low-voltage battery 240, and the other end of the first DCDC converter 230 can be connected to the output side of the vehicle charger 220. In this case: the reverse charging function of the first DCDC converter 230 can be used to charge the output end of the vehicle charger 220 to the target voltage, and the bus voltage of the vehicle charger 220 is powered by the AC input terminal 210 to achieve soft start.

[0083] (5) Fig. 9 A schematic diagram of the structure of a vehicle charging system provided in another embodiment of the present application is shown in FIG. Fig. 9As shown, the vehicle charging system may include: an AC input terminal 210, a rectifier circuit 221b, a bidirectional isolated DCDC converter 222a, a high voltage battery 250, a first DCDC converter 230, and a low voltage battery 240. The AC input terminal 210 is connected to the rectifier circuit 221b, the rectifier circuit 221b is connected to the bidirectional isolated DCDC converter 222a, and the bidirectional isolated DCDC converter 222a is connected to the high voltage battery 250. Fig. 9 In the vehicle charging system shown, the vehicle charger 220 may be composed of a rectifier circuit 221b and a bidirectional isolated DCDC converter 222a, one end of the first DCDC converter 230 may be connected to the low voltage battery 240, and the other end of the first DCDC converter 230 may be connected to the output side of the vehicle charger 220. In this case: the reverse charging function of the first DCDC converter 230 may be used to charge the output end of the vehicle charger 220 to the required voltage, and then the bidirectional isolated DCDC converter 222a of the vehicle charger 220 may be turned on, and after the bus voltage of the vehicle charger 220 is charged to the target voltage, the working state of the bidirectional isolated DCDC converter 222a and the first DCDC converter 230 in the vehicle charger 220 may be controlled so that the voltage is maintained at the required voltage.

[0084] (6) Fig.10 A schematic diagram of the structure of a vehicle charging system provided in another embodiment of the present application is shown in FIG. Fig.10 As shown, the vehicle charging system may include: an AC input terminal 210, a correction circuit 221a, a bidirectional isolated DCDC converter 222a, a high voltage battery 250, a first DCDC converter 230, and a low voltage battery 240. The AC input terminal 210 is connected to the correction circuit 221a, the correction circuit 221a is connected to the bidirectional isolated DCDC converter 222a, and the bidirectional isolated DCDC converter 222a is connected to the high voltage battery 250. Figure 8 In the vehicle charging system shown, the vehicle charger 220 may be composed of a correction circuit 221a and a bidirectional isolated DCDC converter 222a, one end of the first DCDC converter 230 may be connected to the low voltage battery 240, and the other end of the first DCDC converter 230 may be connected to the output side of the vehicle charger 220. In this case: the reverse charging function of the first DCDC converter 230 may be utilized to charge the output end of the vehicle charger 220 to the target voltage, then turn on the bidirectional isolated DCDC converter 222a of the vehicle charger 220, and after charging the bus voltage of the vehicle charger 220 to the target voltage, control the working states of the bidirectional isolated DCDC converter 222a and the first DCDC converter 230 in the vehicle charger 220 so that the voltage is maintained at the required voltage.

[0085] The second DC power supply terminal is connected to one end of the second DCDC converter 222 , or to the other end of the second DCDC converter 222 .

[0086] In this embodiment, by adopting a DCDC converter, when the first secondary switch tube and the second secondary switch tube of the DCDC converter are closed, the low-voltage battery is charged from the excitation inductance of the transformer; when the first secondary switch tube and the second secondary switch tube are disconnected, the energy from the transformer excitation inductance is transmitted to the primary capacitor, realizing the reverse flow of energy, that is, realizing the reverse charging function, thereby realizing the pre-charging function of the OBC bus and the high-voltage battery side of the whole vehicle, thereby eliminating the pre-charging circuit of the OBC (on-board charger) and the high-voltage battery side, while improving the power density and safety of the OBC, it also reduces the cost of the OBC and the whole vehicle.

[0087] Fig.11 A schematic diagram of the structure of a vehicle charging system provided in an embodiment of the present application is shown in FIG. Fig.11 As shown, the vehicle charging system 300 includes: a vehicle charging device 200 and a control circuit 310 .

[0088] The on-board charging device 200 includes an AC input terminal 210, an on-board charger 220, a DCDC converter, a high-voltage battery 250 and a low-voltage battery 240. The control circuit 310 is electrically connected to the on-board charging device 200 and is used to control the working state of the on-board charging device 200.

[0089] The on-board charger 220 includes: a circuit module 221 and a second DCDC converter 222; the AC input terminal 210 is connected to one end of the second DCDC converter 222 through the circuit module, and the other end of the second DCDC converter 222 is connected to the high-voltage battery 250; the second DC power supply terminal is connected to one end of the second DCDC converter 222, or, to the other end of the second DCDC converter 222.

[0090] The on-board charging system 300 includes: the on-board charging device realizes reverse charging from the low-voltage battery to the on-board charger, thereby realizing the pre-charging function of the low-voltage battery to the OBC bus and the high-voltage battery side of the whole vehicle, thereby eliminating the pre-charging circuit between the OBC and the high-voltage battery side, while improving the power density and safety of the OBC, it also reduces the cost of the OBC and the whole vehicle.

[0091] It should be noted that in the specific working process of the on-board charging system 300: the control circuit 310 is connected to the vehicle controller through a communication line, and is used to receive the working instructions sent by the vehicle controller, and according to the received working instructions, controls the working state of the on-board charging device 200 through partial or complete connection with the on-board charging device 200. When no instruction to start working is received, the control circuit 310 controls the on-board charging device 200 to be in a dormant state; if an instruction to start working is received, the control circuit 310 wakes up the on-board charging device 200 and puts it in a pre-dormant state; then the control circuit 310 determines whether the high-voltage battery 250 of the whole vehicle is connected. If the high-voltage battery 250 is not connected, the on-board charging device 200 is controlled to work in a pre-charging state (the pre-charging state is that the low-voltage battery 240 charges at least one bus in the on-board charger 220 through the second DCDC converter 222 in the flyback circuit mode); if the high-voltage battery 250 is in a connected state, the on-board charging device 200 is controlled to work in a whole vehicle working state (the whole vehicle working state is that the whole vehicle is in a charging state, an inverter state or a single DCDC working state).

[0092] Furthermore, in the pre-charging state, the control circuit 310 also needs to determine whether a reverse pre-charging instruction is received. If so, the second DCDC converter 222 is controlled to work in the flyback circuit mode, and the low-voltage battery 240 is converted to charge at least one bus in the on-board charger 220 through the flyback circuit, and when the high-voltage battery 250 of the whole vehicle is in the connected state, the flyback circuit mode is controlled to stop; if no reverse pre-charging instruction is received, it enters the pre-sleep state. In the whole vehicle working state, it is necessary to further wait for the whole vehicle working instruction. When the whole vehicle working instruction has not arrived, the whole vehicle is in the standby state. When the whole vehicle working instruction arrives, the whole vehicle is controlled to be in the charging state, the inverter state or the single DCDC working state according to the working instruction.

[0093] In the several embodiments provided in the present application, it should be understood that the disclosed devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0094] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0095] In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of hardware plus software functional units.

[0096] The above-mentioned integrated unit implemented in the form of a software functional unit can be stored in a computer-readable storage medium. The above-mentioned software functional unit is stored in a storage medium, including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) or a processor (English: processor) to perform some steps of the method described in each embodiment of the present application. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (English: Read-Only Memory, abbreviated: ROM), random access memory (English: Random Access Memory, abbreviated: RAM), disk or optical disk and other media that can store program codes.

Claims

1. A DC-DC converter for a vehicle charging system, characterized in that: include: A first DC power supply terminal, a main transformer, a first circuit located on a secondary side of the main transformer, a second circuit located on a primary side of the main transformer, and a second DC power supply terminal; The first DC power supply end is used to connect to the low-voltage battery of the vehicle charging system, and the second DC power supply end is used to connect to the vehicle charger of the vehicle charging system; The first circuit includes: a slave transformer and a secondary switch tube, one end of the secondary inductor of the slave transformer is connected to the positive electrode of the first DC power supply terminal, and the other end of the secondary inductor of the slave transformer is connected to the secondary inductor of the main transformer; the other end of the secondary inductor of the slave transformer is also connected to the negative electrode of the first DC power supply terminal through the secondary switch tube; One end of the primary inductor of the slave transformer is grounded, and the other end of the primary inductor of the slave transformer is connected to the positive electrode of the second DC power supply terminal through a diode; The second circuit includes: a primary capacitor and a primary switch tube, one end of the primary inductor of the main transformer is connected to the positive and negative electrodes of the second DC power supply terminal respectively through the two primary switch tubes; the other end of the primary inductor of the main transformer is connected to the positive and negative electrodes of the second DC power supply terminal respectively through the two primary capacitors.

2. The DCDC converter according to claim 1, characterized in that: The slave transformer includes: a first slave transformer and a second slave transformer; the secondary side switch tube includes: a first secondary side switch tube and a second secondary side switch tube; One end of the secondary inductance of the first slave transformer and the second slave transformer is connected to the positive electrode of the first DC power supply terminal, the other end of the secondary inductance of the first slave transformer is connected to one end of the secondary inductance of the main transformer, and the other end of the secondary inductance of the second slave transformer is connected to the other end of the secondary inductance of the main transformer; The other end of the secondary inductor of the first slave transformer is connected to the negative electrode of the first DC power supply terminal through the first secondary switch tube; the other end of the secondary inductor of the second slave transformer is connected to the negative electrode of the first DC power supply terminal through the second secondary switch tube; One end of the primary inductance of the first slave transformer and the second slave transformer is grounded, and the other end of the primary inductance of the first slave transformer and the second slave transformer is connected to the positive electrode of the second DC power supply terminal through a diode respectively.

3. The DCDC converter according to claim 1, characterized in that: Said The slave transformer is a transformer; the secondary side switch tube comprises: a third secondary side switch tube and a fourth secondary side switch tube; The other end of the secondary inductor of the slave transformer is connected to one end of the secondary inductor of the main transformer through the third secondary switch tube; the other end of the secondary inductor of the slave transformer is also connected to the other end of the secondary inductor of the main transformer through the fourth secondary switch tube; The middle position of the secondary inductor of the main transformer is connected to the negative electrode of the first DC power supply end.

4. The DCDC converter according to any one of claims 1 to 3, characterized in that: The first DC power supply terminal and the second DC power supply terminal are respectively connected in parallel with a capacitor.

5. A vehicle-mounted charging device, characterized in that: include: AC input terminal, on-board charger, first DC-DC DCDC converter, high voltage battery and low voltage battery; Wherein, the AC input terminal is connected to the high-voltage battery through the on-board charger; The first DCDC converter is a converter as described in any one of claims 1 to 4 above; The first DC power supply end of the first DCDC converter is connected to the low-voltage battery, and the second DC power supply end of the first DCDC converter is connected to the on-board charger.

6. The device according to claim 5, characterized in that The on-board charger comprises: a circuit module and a second DCDC converter; the AC input end is connected to one end of the second DCDC converter through the circuit module, and the other end of the second DCDC converter is connected to the high-voltage battery; The second DC power supply end is connected to one end of the second DCDC converter, or to the other end of the second DCDC converter.

7. The device according to claim 6, characterized in that The circuit module is: a rectifier circuit or a correction circuit; the second DCDC converter is a bidirectional isolated DCDC converter or a unidirectional isolated DCDC converter.

8. A vehicle charging system, characterized in that: include: On-vehicle charging device and control circuit; wherein: The on-board charging device comprises: an AC input terminal, an on-board charger, a DCDC converter, a high-voltage battery and a low-voltage battery; wherein the DCDC converter is the DCDC converter described in any one of claims 1 to 4 above; the on-board charging device is the on-board charging device described in any one of claims 5 to 7 above; The control circuit is electrically connected to the vehicle-mounted charging device and is used to control the working state of the vehicle-mounted charging device.

9. The system according to claim 8, characterized in that The on-board charger comprises: a circuit module and a second DCDC converter; the AC input end is connected to one end of the second DCDC converter through the circuit module, and the other end of the second DCDC converter is connected to the high-voltage battery; The second DC power supply end is connected to one end of the second DCDC converter, or to the other end of the second DCDC converter.

10. A means of transport, characterized in that: include: The on-vehicle charging system as described in claim 8 above.

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