Charging circuit of on-board charger and on-board charger

Abstract

The application discloses a charging circuit of a vehicle-mounted charger and the vehicle-mounted charger, and relates to the technical field of vehicle-mounted chargers.The charging circuit of the vehicle-mounted charger comprises a main switching module, a front-stage conversion module, a bus capacitor module and a rear-stage isolation module which are sequentially connected, a loop switching module connected with the bus capacitor module and the main switching module respectively, and a control module connected with the main switching module, the front-stage conversion module, the rear-stage isolation module and the loop switching module respectively.The main switching module comprises three-phase main switches, and the loop switching module comprises loop switches.Through controlling the working mode of the three-phase main switches and the on-off of the loop switches, the charging circuit can work in a three-phase charging and discharging mode, a single-phase charging and discharging mode or a split-phase charging and discharging mode.The number of switch devices for mode switching is small, the size of the multi-mode OBC is reduced, and the technical problem of small power density of the multi-mode OBC is solved.

Description

Technical Field

[0001] This application relates to the field of on-board charger technology, and in particular to a charging circuit and an on-board charger. Background Technology

[0002] As electric vehicles become increasingly popular worldwide, the On-Board Charger (OBC), a core component that converts AC power from the grid into DC power to charge the battery, needs to be able to adapt to the grid requirements of different countries or regions.

[0003] In related technologies, multiple relays are incorporated into the OBC (On-Board Cell) to enable switching between multiple operating modes, allowing the OBC to adapt to the power grid requirements of different countries or regions. However, this mode-switching scheme requires a large number of relays, which occupies a significant amount of space in the OBC, resulting in a larger size and lower power density. Summary of the Invention

[0004] The main purpose of this application is to propose a charging circuit and an on-board charger, which aims to solve the technical problem of low power density of multi-mode OBCs in related technologies.

[0005] To achieve the above objectives, this application proposes a charging circuit for an on-board charger, comprising: The system comprises a main switching module, a pre-stage conversion module, a bus capacitor module, and a post-stage isolation module connected in sequence; a loop switching module connected to the bus capacitor module and the main switching module respectively; and a control module connected to the main switching module, the pre-stage conversion module, the post-stage isolation module, and the loop switching module respectively; wherein the main switching module includes a three-phase main switch, and the loop switching module includes a loop switch. The control module controls the three-phase main switch, enabling the main switching module to switch between three-phase connection mode and single-phase connection mode, and controls the on / off state of the circuit switch, so that the charging circuit can operate in three-phase charging / discharging mode, single-phase charging / discharging mode, or split-phase charging / discharging mode. Specifically, in three-phase charging / discharging mode, the main switching module switches to three-phase connection mode and the circuit switch is turned on; in single-phase charging / discharging mode, the main switching module switches to single-phase connection mode and the circuit switch is turned off; in split-phase charging / discharging mode, the main switching module switches to three-phase connection mode and the circuit switch is turned off.

[0006] In one embodiment, the three-phase main switch includes a first main switch, a second main switch, and a third main switch; The first terminal of the first main switch is connected to the first AC terminal of the AC charging / discharging interface, the second terminal of the first main switch is connected to the first AC terminal of the pre-conversion module, the first terminal of the second main switch is connected to the second AC terminal of the AC charging / discharging interface, the second terminal of the second main switch is connected to the second AC terminal of the pre-conversion module, the first terminal of the third main switch is connected to the third AC terminal of the AC charging / discharging interface, the second terminal of the third main switch is connected to the third AC terminal of the pre-conversion module, and the control terminals of the first, second, and third main switches are all connected to the control module.

[0007] In one embodiment, the front-end conversion module includes a three-phase four-wire bridge circuit; The first AC terminal of the three-phase four-wire bridge circuit is connected to the second terminal of the first main switch. The second AC terminal of the three-phase four-wire bridge circuit is connected to the second terminal of the second main switch. The third AC terminal of the three-phase four-wire bridge circuit is connected to the second terminal of the third main switch. The fourth AC terminal of the three-phase four-wire bridge circuit is connected to the fourth AC terminal of the AC charging and discharging interface. The first DC terminal of the three-phase four-wire bridge circuit is connected to the first terminal of the bus capacitor module. The second DC terminal of the three-phase four-wire bridge circuit is connected to the second terminal of the bus capacitor module. The control terminals of each power device in the three-phase four-wire bridge circuit are all connected to the control module.

[0008] In one embodiment, the control module is further configured to: Based on a dual-closed-loop control method using three-dimensional spatial vector modulation and a synchronous rotating coordinate system, the power devices in the three-phase four-wire bridge circuit are controlled to enable the front-end conversion module to perform three-phase charging and discharging or split-phase charging and discharging, so that the charging circuit operates in three-phase charging and discharging mode or split-phase charging and discharging mode; or... Based on the sinusoidal pulse width modulation method and the dual closed-loop control method of synchronous rotating coordinate system, the power devices in the three-phase four-wire bridge circuit are controlled to enable the front-end conversion module to perform single-phase charging and discharging, so that the charging circuit operates in single-phase charging and discharging mode.

[0009] In one embodiment, the loop switching module further includes a first capacitor, a second capacitor, a third capacitor, and a fourth capacitor; One end of the first capacitor is connected to the second end of the first main switch, one end of the second capacitor is connected to the second end of the second main switch, one end of the third capacitor is connected to the second end of the third main switch, one end of the fourth capacitor is connected to the fourth AC terminal of the AC charging and discharging interface, the other ends of the first capacitor, the second capacitor, the third capacitor and the fourth capacitor are all connected to the first end of the circuit switch, the second end of the circuit switch is connected to the third end of the bus capacitor module, and the control terminal of the circuit switch is connected to the control module.

[0010] In one embodiment, a pre-charge module is also included; The pre-charge module includes a first pre-charge unit, a second pre-charge unit, and a third pre-charge unit. The first pre-charge unit is connected in parallel with the first main switch, the second pre-charge unit is connected in parallel with the second main switch, and the third pre-charge unit is connected in parallel with the third main switch. The first pre-charge unit is used to provide current limiting protection for the first main switch; The second pre-charge unit is used to provide current-limiting protection for the second main switch; The third pre-charge unit is used to provide current-limiting protection for the third main switch.

[0011] In one embodiment, the downstream isolation module includes a DC-DC conversion circuit, which is connected to the control module, the bus capacitor module, and the DC charging / discharging interface, respectively. The DC-DC conversion circuit is used to perform voltage conversion processing on the first initial DC voltage input to the bus capacitor module according to the voltage conversion control signal sent by the control module, to obtain a first target DC voltage for output through the DC charging and discharging interface, or to perform voltage conversion processing on the second initial DC voltage input to the DC charging and discharging interface to obtain a second target DC voltage for storage through the bus capacitor module.

[0012] In one embodiment, a DC filter module is also included, which is connected to the DC-DC conversion circuit and the DC charging / discharging interface, respectively. The DC filter module is used to suppress electromagnetic interference on the first target DC voltage input to the DC-DC conversion circuit, obtain the filtered first target DC voltage and provide it to the DC charging and discharging interface, or to suppress electromagnetic interference on the second initial DC voltage input to the DC charging and discharging interface, obtain the filtered second initial DC voltage and provide it to the DC-DC conversion circuit.

[0013] In one embodiment, an AC filtering module is also included, which is connected to both the main switching module and the pre-conversion module. The AC filtering module is used to perform battery interference suppression processing on the first initial AC voltage input to the main switching module to obtain the first target AC voltage and provide it to the front-end conversion module, or to perform electromagnetic interference suppression processing on the second initial AC voltage input to the front-end conversion module to obtain the second target AC voltage and provide it to the main switching module.

[0014] In addition, to achieve the above objectives, this application also proposes an on-board charger, including the charging circuit of the on-board charger as described above.

[0015] One or more technical solutions proposed in this application have at least the following technical effects: This application provides a charging circuit for an on-board charger. By controlling the operating mode of the three-phase main switch and the on / off state of the circuit switch in the main switching module, the charging circuit can operate in three-phase charging / discharging mode, single-phase charging / discharging mode, or split-phase charging / discharging mode. Only the on / off state of four switches needs to be controlled to switch the operating mode of the on-board charger's charging circuit, thus adapting to the power grid requirements of different countries or regions. Compared with setting multiple relays in the OBC, the number of switching devices is reduced, effectively reducing the size of the multi-mode OBC and thereby improving the power density of the multi-mode OBC, solving the technical problem of low power density of multi-mode OBCs in related technologies. Attached Figure Description

[0016] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0017] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the charging circuit of an embodiment of the on-board charger of this application; Figure 2 This is another structural schematic diagram of an embodiment of the charging circuit of the on-board charger of this application; Figure 3 This is a circuit diagram of the pre-conversion module, bus capacitor module and loop switching module in one embodiment of the charging circuit of the on-board charger of this application; Figure 4 A diagram illustrating a dual-closed-loop control strategy based on a synchronous rotating coordinate system, provided for an embodiment of the charging circuit of the on-board charger of this application; Figure 5 This is a 3D-SVPWM switching vector diagram of a three-phase four-wire bridge circuit in the abc coordinate system, provided as an embodiment of the charging circuit of the on-board charger of this application.

[0019] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0020] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0021] It should be noted that in this application, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that an apparatus or system comprising a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such an apparatus or system. Without further limitation, an element defined by the phrase "comprising..." does not exclude the presence of other identical elements in the apparatus or system that includes that element.

[0022] In this application, unless otherwise expressly specified and limited, the terms "connection," "fixed," etc., should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral part; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0023] In this application, descriptions involving "first," "second," etc., are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features.

[0024] In this application, the suffixes such as "module," "component," or "unit" used to denote elements are used only for illustrative purposes and have no specific meaning in themselves. Therefore, "module," "component," or "unit" can be used interchangeably. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances. Furthermore, the technical solutions of the various embodiments can be combined with each other, but only on the basis of being achievable by those skilled in the art. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed in this application.

[0025] As electric vehicles become increasingly popular globally, the On-Board Charger (OBC), a core component that converts AC power from the grid into DC power to charge the battery, needs to adapt to the grid requirements of different countries and regions. OBCs are mainly categorized into two types: Central European versions and North American versions. The Central European version of the OBC also offers both three-phase and single-phase operating modes, and each mode enables both charging and discharging.

[0026] In related technologies, multiple relays are incorporated into the On-Board Cell (OBC) to enable switching between multiple operating modes, allowing the OBC to adapt to the power grid requirements of different countries or regions. However, this mode-switching scheme requires a large number of relays, occupying significant space within the OBC and resulting in a larger size and lower power density. Furthermore, the mode-switching complexity of multi-mode OBCs based on multiple relays is high, and the switching control is difficult, leading to lower reliability.

[0027] To address the aforementioned problems, this application provides a charging circuit for an on-board charger and an on-board charger itself. The application and its embodiments will be described below with reference to the accompanying drawings.

[0028] This application proposes a charging circuit for an on-board charger.

[0029] In one embodiment of the charging circuit of the on-board charger, referring to Figure 1 , Figure 1 This is a schematic diagram of the structure of this embodiment. The charging circuit of the on-board charger can be applied to the on-board charger of an electric vehicle. The charging circuit may include: The system comprises a main switching module, a pre-stage conversion module, a bus capacitor module, and a post-stage isolation module connected in sequence; a loop switching module connected to the bus capacitor module and the main switching module respectively; and a control module connected to the main switching module, the pre-stage conversion module, the post-stage isolation module, and the loop switching module respectively; wherein the main switching module includes a three-phase main switch, and the loop switching module includes a loop switch. The control module controls the three-phase main switch, enabling the main switching module to switch between three-phase connection mode and single-phase connection mode, and controls the on / off state of the circuit switch, so that the charging circuit can operate in three-phase charging / discharging mode, single-phase charging / discharging mode, or split-phase charging / discharging mode. Specifically, in three-phase charging / discharging mode, the main switching module switches to three-phase connection mode and the circuit switch is turned on; in single-phase charging / discharging mode, the main switching module switches to single-phase connection mode and the circuit switch is turned off; in split-phase charging / discharging mode, the main switching module switches to three-phase connection mode and the circuit switch is turned off.

[0030] It should be noted that the main switching module can be connected to the AC charging / discharging interface, through which an AC power supply or AC load can be connected. The subsequent isolation module can also be connected to the DC charging / discharging interface, through which a DC power supply or DC load can be connected. The AC power supply can be a three-phase AC power supply or a single-phase AC power supply, and the AC load can be a three-phase AC load or a single-phase AC load. The DC power supply can be the vehicle's power battery, and the DC load can be various DC devices in the vehicle control system.

[0031] It is understandable that the main switching module can operate in three-phase connection mode and single-phase connection mode. When the AC charging / discharging interface is connected to a three-phase AC power supply or a three-phase AC load, the main switching module operates in three-phase connection mode, connecting the pre-conversion module to the three-phase AC power supply or the pre-conversion module to the three-phase AC load. When the AC charging / discharging interface is connected to a single-phase AC power supply or a single-phase AC load, the main switching module operates in single-phase connection mode, connecting the pre-conversion module to the single-phase AC power supply or the pre-conversion module to the single-phase AC load.

[0032] In one feasible implementation, refer to Figure 2 , Figure 2 This is another structural diagram of this embodiment, which needs to be explained. Figure 2 The three-phase main switches (not shown) include a first main switch K1, a second main switch K2, and a third main switch K3. The first terminal of the first main switch K1 is connected to the first AC terminal of the AC charging and discharging interface, the second terminal of the first main switch K1 is connected to the first AC terminal of the pre-conversion module, the first terminal of the second main switch K2 is connected to the second AC terminal of the AC charging and discharging interface, the second terminal of the second main switch K2 is connected to the second AC terminal of the pre-conversion module, the first terminal of the third main switch K3 is connected to the third AC terminal of the AC charging and discharging interface, the second terminal of the third main switch K3 is connected to the third AC terminal of the pre-conversion module, and the control terminals of the first main switch K1, the second main switch K2, and the third main switch K3 are all connected to the control module.

[0033] It should be noted that, as Figure 2As shown, the first terminal of the first main switch K1 is connected to the first AC terminal 1 of the AC charging / discharging interface AC, the first terminal of the second main switch K2 is connected to the second AC terminal 2 of the AC charging / discharging interface AC, and the first terminal of the third main switch K3 is connected to the third AC terminal 3 of the AC charging / discharging interface AC. The first main switch K1, the second main switch K2, the third main switch K3, and the loop switch K4 can all be relays. The control module can be an MCU (Microcontroller Unit) chip or a DSP (Digital Signal Processing) chip. The control module can generate switching control signals based on the detected number of phases of the AC power supply or AC load connected to the AC charging / discharging interface AC, controlling the on / off states of the first main switch K1, the second main switch K2, and the third main switch K3. The main switching module operates in a three-phase connection mode, where the first main switch K1, the second main switch K2, and the third main switch K3 are all on. In a single-phase connection mode, any one of the first main switch K1, the second main switch K2, and the third main switch K3 is on, while the other main switches are off. Preferably, in a single-phase connection mode, the first main switch K1 is on, while the second main switch K2 and the third main switch K3 are off.

[0034] It is understood that the charging circuit may also include a drive module, which may include a first drive unit. The first drive unit is connected to the control module, the control terminal of the first main switch K1, the control terminal of the second main switch K2, and the control terminal of the third main switch K3, respectively. It is used to generate a switch drive signal according to the switch control signal and control the on / off state of the first main switch K1, the second main switch K2, and the third main switch K3. The first drive unit may be a relay drive circuit.

[0035] Additionally, it should be noted that the pre-conversion module can perform AC-DC conversion on the AC power input to the main switching module, obtaining DC power input to the bus capacitor module. The pre-conversion module can also perform DC-AC conversion on the DC power input to the bus capacitor module, obtaining AC power supplied to the main switching module, which then outputs it to the AC load. The pre-conversion module can be a three-phase bridge rectifier circuit or a three-phase four-wire bridge rectifier circuit.

[0036] In one feasible implementation, refer to Figure 3 , Figure 3 The circuit diagram of the front-end conversion module, bus capacitor module and loop switching module in this embodiment is shown. The front-end conversion module may include a three-phase four-wire bridge circuit. The first AC terminal of the three-phase four-wire bridge circuit is connected to the second terminal of the first main switch K1. The second AC terminal of the three-phase four-wire bridge circuit is connected to the second terminal of the second main switch K2. The third AC terminal of the three-phase four-wire bridge circuit is connected to the second terminal of the third main switch K3. The fourth AC terminal of the three-phase four-wire bridge circuit is connected to the fourth AC terminal of the AC charging and discharging interface. The first DC terminal of the three-phase four-wire bridge circuit is connected to the first terminal of the bus capacitor module. The second DC terminal of the three-phase four-wire bridge circuit is connected to the second terminal of the bus capacitor module. The control terminals of each power device in the three-phase four-wire bridge circuit are all connected to the control module.

[0037] It should be noted that, as Figure 3As shown, the three-phase four-wire bridge circuit includes a first bridge arm composed of power devices Q1 and Q2 connected in series, a second bridge arm composed of power devices Q3 and Q4 connected in series, a third bridge arm composed of power devices Q5 and Q6 connected in series, a fourth bridge arm composed of power devices Q7 and Q8 connected in series, a first inductor L1, a second inductor L2, a third inductor L3, and a fourth inductor L4. The first, second, third, and fourth bridge arms are connected in parallel to form the first DC terminal and the second DC terminal of the three-phase four-wire bridge circuit. One end of the first inductor L1 is connected to the first bridge arm. The midpoint of the arm is connected, and the other end of the first inductor L1 forms the first AC terminal of the three-phase four-wire bridge circuit. One end of the second inductor L2 is connected to the midpoint of the second bridge arm, and the other end of the second inductor L1 forms the second AC terminal of the three-phase four-wire bridge circuit. One end of the third inductor L3 is connected to the midpoint of the third bridge arm, and the other end of the third inductor L3 forms the third AC terminal of the three-phase four-wire bridge circuit. One end of the fourth inductor L1 is connected to the midpoint of the fourth bridge arm, and the other end of the fourth inductor L1 forms the fourth AC terminal of the three-phase four-wire bridge circuit. The fourth AC terminal of the three-phase four-wire bridge circuit is connected to the fourth AC terminal 4 of the AC charging and discharging interface AC. The control module is connected to the control terminals of power devices Q1, Q2, Q3, Q4, Q5, Q6, Q7, and Q8, respectively. It outputs power control signals to control the on / off states of these devices, enabling the three-phase four-wire bridge circuit to operate in three-phase charging / discharging mode, single-phase charging / discharging mode, or split-phase charging / discharging mode. In three-phase charging / discharging mode, all four arms of the three-phase four-wire bridge circuit work together. In split-phase charging / discharging mode, the first and second arms are connected in parallel, and the third and fourth arms are connected in parallel, forming two parallel single-phase totem-pole bridgeless PFC (Power Factor Correction) circuits. Power devices Q1, Q2, Q3, Q4, Q5, Q6, Q7, and Q8 can be power devices such as IGBTs (Insulated Gate Bipolar Transistors) and MOS-FETs (Metal-Oxide-Semiconductor Field-Effect Transistors).

[0038] Understandably, the control module can determine the operating mode of the three-phase four-wire bridge circuit based on the type of AC power supply or AC load connected to the AC charging / discharging interface, and output the corresponding power control signal to control the three-phase four-wire bridge circuit to enter the corresponding operating mode. The type of AC power supply or AC load may include the power grid type of different countries or regions, the load type of different countries or regions, etc.

[0039] In addition, it is understandable that, such as Figure 2 As shown, the drive module may further include a second drive unit, which is connected to the control module, the control terminals of power devices Q1, Q2, Q3, Q4, Q5, Q6, Q7, and Q8 respectively. This second drive unit generates a power drive signal based on the power control signal, and controls the on / off states of power devices Q1, Q2, Q3, Q4, Q5, Q6, Q7, and Q8 to control the three-phase four-wire bridge circuit to achieve power conversion.

[0040] In one feasible implementation, such as Figure 3 As shown, the bus capacitor module may include a fifth capacitor C5 and a sixth capacitor C6. One end of the fifth capacitor C5 forms the first end of the bus capacitor module and is connected to the first DC terminal of the three-phase four-wire bridge circuit. The other end of the fifth capacitor C5 and one end of the sixth capacitor C6 are connected together to form the third end of the bus capacitor module and are connected to the first terminal of the circuit switch K4. The other end of the sixth capacitor C6 forms the second end of the bus capacitor module and is connected to the second DC terminal of the three-phase four-wire bridge circuit.

[0041] It should be noted that the second terminal of the loop switch K4 is connected to the second terminals of the first main switch K1, the second main switch K2, the third main switch K3, and the fourth AC terminal 4 of the AC charging / discharging interface. The control terminal of the loop switch K4 is connected to the control module. The control module can generate a loop control signal based on the type of AC power supply or AC load connected to the AC charging / discharging interface, thereby controlling the on / off state of the loop switch K4. Specifically, in single-phase charging / discharging mode, the control module outputs a loop control signal, causing the loop switch K4 to open. In three-phase charging / discharging mode, if the AC power supply is a European or Chinese version, or the AC load is a European or Chinese version, the control module generates a loop control signal, causing the loop switch K4 to open. If the AC power supply is a North American version, or the AC load is a North American version, the control module generates a loop control signal, causing the loop switch K4 to open.

[0042] Understandably, the second drive unit is also connected to the control terminal of the loop switch K4, and is used to generate a loop drive signal based on the loop control signal sent by the control module, and control the on / off state of the loop switch K4.

[0043] In one feasible implementation, the control module is further configured to: Based on a dual-closed-loop control method using three-dimensional spatial vector modulation and a synchronous rotating coordinate system, the power devices in the three-phase four-wire bridge circuit are controlled to enable the front-end conversion module to perform three-phase charging and discharging or split-phase charging and discharging, so that the charging circuit operates in three-phase charging and discharging mode or split-phase charging and discharging mode; or... Based on the sinusoidal pulse width modulation method and the dual closed-loop control method of synchronous rotating coordinate system, the power devices in the three-phase four-wire bridge circuit are controlled to enable the front-end conversion module to perform single-phase charging and discharging, so that the charging circuit operates in single-phase charging and discharging mode.

[0044] It should be noted that when the three-phase four-wire bridge circuit operates in three-phase charging / discharging mode or split-phase charging / discharging mode, the control module adopts a 3D-SVPWM (Three-dimensional Space Vector Pulse Width Modulation) modulation method based on the abc coordinate system and a dual closed-loop control method based on the synchronous rotating coordinate system to determine the switching vector of each power device in the three-phase four-wire bridge circuit and control each power device. When the three-phase four-wire bridge circuit operates in single-phase charging / discharging mode, the control module adopts an SPWM (Sinusoidal Pulse Width Modulation) modulation method and a dual closed-loop control method based on the synchronous rotating coordinate system to determine the switching vector of each power device in the three-phase four-wire bridge circuit and control each power device.

[0045] like Figure 2 As shown, the charging circuit may further include an AC voltage sampling module, which is connected to the second terminal of the first main switch K1, the second terminal of the second main switch K2, the second terminal of the third main switch K3, and the control module, respectively, for collecting the AC voltage V of the first main switch K1. a The AC voltage V of the second main switch K2 b AC voltage V of the third main switch K3 c And the collected AC voltage V a AC voltage V c and AC voltage V c The signal is sent to the control module. The charging circuit may also include an AC current sampling module, connected to the other ends of the first inductor L1, the second inductor L2, the third inductor L3, and the control module, respectively, for collecting the AC current I of the first inductor L1. aThe alternating current I of the second inductor L2 b and the alternating current I of the third inductor L3 c and the collected alternating current I a Alternating current I c and alternating current I c The signal is sent to the control module. The charging circuit may also include a bus voltage sampling module, connected to one end of the fifth capacitor C1 and the control module respectively, for acquiring the bus DC voltage V from the bus capacitor module. bus And the collected bus DC voltage V bus Send to the control module.

[0046] In one example, refer to Figure 4 and Figure 5 , Figure 4 This is a diagram of the dual closed-loop control strategy based on a synchronous rotating coordinate system provided in this embodiment. Figure 5 This is a 3D-SVPWM switching vector diagram of the three-phase four-wire bridge circuit in the abc coordinate system provided in this embodiment. The control module receives the AC voltage V sent by the AC voltage sampling module. a AC voltage V c and AC voltage V c And the AC current I sent by the AC current sampling module a Alternating current I c and alternating current I c Then, the AC voltage V a AC voltage V c AC voltage V c Alternating current I a Alternating current I c and alternating current I c By performing a coordinate system transformation, the direct-axis voltage V in the two-phase rotating coordinate system is obtained. d Cross-axis voltage V q Zero-sequence voltage V0, direct-axis current I d Quadrature axis current I q And the zero-sequence current I0, combined with the reference direct-axis current I corresponding to the reference AC current. d1 Reference quadrature axis current I q1 and reference zero-sequence current I 01 and the DC voltage V of the bus bus and reference DC voltage V bus1A dual closed-loop control method with a current loop as the inner loop and a voltage loop as the outer loop is used to generate power control signals. Combined with 3D-SPWM modulation, the power drive signals g1, g2, g3, g4, g5, g6, g7, and g8 of power devices Q1, Q2, Q3, Q4, Q5, Q6, Q7, and Q8 are determined to control each power device.

[0047] In one feasible implementation, such as Figure 3 As shown, the circuit switching module may also include a first capacitor C1, a second capacitor C2, a third capacitor C3, and a fourth capacitor C4. One end of the first capacitor C1 is connected to the second end of the first main switch K1, one end of the second capacitor C2 is connected to the second end of the second main switch K2, one end of the third capacitor C3 is connected to the second end of the third main switch K3, one end of the fourth capacitor C4 is connected to the fourth AC terminal of the AC charging and discharging interface, the other ends of the first capacitor C1, the second capacitor C2, the third capacitor C3 and the fourth capacitor C4 are all connected to the first end of the circuit switch K4, the second end of the circuit switch K4 is connected to the third terminal of the bus capacitor module, and the control terminal of the circuit switch K4 is connected to the control module.

[0048] It should be noted that one end of the fourth capacitor C4 is connected to the fourth AC terminal 4 of the AC charging / discharging interface. In three-phase charging / discharging mode, the control module control circuit switch K4 is turned on, connecting the first capacitor C1, the second capacitor C2, the third capacitor C3, and the fourth capacitor C4 to the midpoint of the fifth capacitor C5 and the sixth capacitor C6. This provides a current loop for the common-mode current at the midpoint, improving the EMC (Electromagnetic Compatibility) performance of the charging circuit.

[0049] In one feasible implementation, the downstream isolation module may include a DC-DC conversion circuit, which is connected to the control module, the bus capacitor module and the DC charging and discharging interface respectively. The DC-DC conversion circuit is used to perform voltage conversion processing on the first initial DC voltage input to the bus capacitor module according to the voltage conversion control signal sent by the control module, to obtain a first target DC voltage for output through the DC charging and discharging interface, or to perform voltage conversion processing on the second initial DC voltage input to the DC charging and discharging interface to obtain a second target DC voltage for storage through the bus capacitor module.

[0050] It should be noted that the DC-DC conversion circuit can be a bidirectional CLLC (Capacitor-Inductor-Inductor-Capacitor) resonant converter or a DAB (Dual Active Bridge) converter. For example... Figure 2 As shown, the first DC terminal of the DC-DC converter circuit is connected to the first terminal of the bus capacitor module, the second DC terminal of the DC-DC converter circuit is connected to the second terminal of the bus capacitor module, the third DC terminal of the DC-DC converter circuit is connected to the first terminal 1 of the DC charging / discharging interface HVDC, and the fourth DC terminal of the DC-DC converter circuit is connected to the second terminal 2 of the DC charging / discharging interface HVDC. The drive module may further include a third drive unit, which is connected to the control terminals of each power device in the DC-DC converter circuit and the control module, respectively. This third drive unit generates conversion drive signals based on the voltage conversion control signals sent by the control module, controlling the on / off states of each power device in the DC-DC converter circuit to enable the DC-DC converter circuit to perform voltage conversion.

[0051] It is understandable that, such as Figure 2 As shown, the charging circuit of the on-board charger may further include a DC voltage sampling module. The DC voltage sampling module includes a first DC voltage sampling unit and a second DC voltage sampling unit. The first DC voltage sampling unit is connected to the third DC terminal of the DC-DC conversion circuit and the control module, and is used to collect the first DC voltage of the third DC terminal of the DC-DC conversion circuit and send the collected first DC voltage to the control module. The second DC voltage sampling unit is connected to the fourth DC terminal of the DC-DC conversion circuit and the control module, and is used to collect the second DC voltage of the fourth DC terminal of the DC-DC conversion circuit and send the collected second DC voltage to the control module, so that the control module generates a voltage conversion control signal based on the first DC voltage and the second DC voltage.

[0052] In one feasible implementation, such as Figure 2 As shown, the charging circuit of the on-board charger may also include a DC filter module, which is connected to the DC-DC conversion circuit and the DC charging and discharging interface respectively. The DC filter module is used to suppress electromagnetic interference on the first target DC voltage input to the DC-DC conversion circuit, obtain the filtered first target DC voltage and provide it to the DC charging and discharging interface, or to suppress electromagnetic interference on the second initial DC voltage input to the DC charging and discharging interface, obtain the filtered second initial DC voltage and provide it to the DC-DC conversion circuit.

[0053] It should be noted that the DC filter module can be a high-voltage DC EMI (Electromagnetic Interference) filter. The first DC terminal of the DC filter module is connected to the third DC terminal of the DC-DC converter circuit, the second DC terminal of the DC filter module is connected to the fourth DC terminal of the DC-DC converter circuit, the third DC terminal of the DC filter module is connected to the first terminal 1 of the DC charging / discharging interface HVDC, and the fourth DC terminal of the DC filter module is connected to the second terminal 2 of the DC charging / discharging interface HVDC.

[0054] It is understandable that the DC filter module can filter electromagnetic interference in the first target DC voltage or the second initial DC voltage, thereby achieving electromagnetic interference suppression.

[0055] In one feasible implementation, such as Figure 2 As shown, the charging circuit of the on-board charger may also include an AC filter module, which is connected to the main switching module and the pre-conversion module respectively. The AC filtering module is used to perform battery interference suppression processing on the first initial AC voltage input to the main switching module to obtain the first target AC voltage and provide it to the front-end conversion module, or to perform electromagnetic interference suppression processing on the second initial AC voltage input to the front-end conversion module to obtain the second target AC voltage and provide it to the main switching module.

[0056] It should be noted that the AC filter module can be an AC EMI filter. The first AC terminal of the AC filter module is connected to the second terminal of the first main switch K1, the second AC terminal of the AC filter module is connected to the second terminal of the second main switch K2, the third AC terminal of the AC filter module is connected to the second terminal of the third main switch K3, the fourth AC terminal of the AC filter module is connected to the fourth AC terminal 4 of the AC charging / discharging interface AC, the fifth AC terminal of the AC filter module is connected to the first AC terminal of the pre-conversion module, the sixth AC terminal of the AC filter module is connected to the second AC terminal of the pre-conversion module, the seventh AC terminal of the AC filter module is connected to the third AC terminal of the pre-conversion module, and the eighth AC terminal of the AC filter module is connected to the fourth AC terminal of the pre-conversion module.

[0057] It is understandable that the AC filter module can filter electromagnetic interference in the first initial AC voltage or the second initial AC voltage, thereby achieving electromagnetic interference suppression.

[0058] The charging circuit of the on-board charger provided in this embodiment can operate in three-phase charging and discharging mode, single-phase charging and discharging mode, or split-phase charging and discharging mode by controlling the working mode of the three-phase main switch and the on / off state of the circuit switch in the main switching module. Only the on / off state of four switches needs to be controlled to switch the working mode of the charging circuit of the on-board charger, so as to adapt to the power grid requirements of different countries or regions. Compared with setting multiple relays in the OBC, the number of switching devices is reduced, effectively reducing the size of the multi-mode OBC, thereby improving the power density of the multi-mode OBC and solving the technical problem of low power density of multi-mode OBC in related technologies.

[0059] Furthermore, in the charging circuit of the on-board charger provided in this embodiment, as the number of switching devices is reduced, the control difficulty of the switching devices is reduced, simplifying the high complexity of mode switching of the multi-mode OBC, thereby improving the reliability of the multi-mode OBC.

[0060] In another embodiment of the charging circuit of the on-board charger, refer to... Figure 2 The charging circuit of the on-board charger may also include a pre-charge module; The pre-charge module includes a first pre-charge unit, a second pre-charge unit, and a third pre-charge unit. The first pre-charge unit is connected in parallel with the first main switch, the second pre-charge unit is connected in parallel with the second main switch, and the third pre-charge unit is connected in parallel with the third main switch. The first pre-charge unit is used to provide current limiting protection for the first main switch; The second pre-charge unit is used to provide current-limiting protection for the second main switch; The third pre-charge unit is used to provide current-limiting protection for the third main switch.

[0061] It should be noted that, as Figure 2 As shown, the first pre-charge unit may include a first auxiliary switch K5 and a first resistor R1 connected in series; the second pre-charge unit may include a first auxiliary switch K5 and a second resistor R2 connected in series; and the third pre-charge unit may include a third auxiliary switch K7 and a third resistor R3 connected in series. The first auxiliary switch K5, the second auxiliary switch K6, and the third auxiliary switch K7 can all be relays.

[0062] It is understandable that the control terminals of the first auxiliary switch K5, the second auxiliary switch K6, and the third auxiliary switch K7 can all be connected to the control module. The control module can then adjust the input based on the received AC voltage V. a AC voltage V c and AC voltage V cDetermine whether current limiting protection is required for the first main switch K1, the second main switch K2, and the third main switch K3. If current limiting protection is required for the first main switch K1, control the first auxiliary switch K5 to turn on. If current limiting protection is required for the second main switch K2, control the second auxiliary switch K6 to turn on. If current limiting protection is required for the third main switch K3, control the third auxiliary switch K7 to turn on.

[0063] Therefore, in the charging circuit of the on-board charger provided in this embodiment, a pre-charge unit connected in parallel with each main switch is also provided to realize the current limiting protection function of each main switch, thereby further improving the reliability of the charging circuit of the on-board charger.

[0064] This application also proposes an on-board charger.

[0065] In one embodiment of the on-board charger, the on-board charger may include the charging circuit of the on-board charger as described in any of the above embodiments.

[0066] It should be noted that the specific structure of the charging circuit of the vehicle charger is as described in the above embodiments. Since the vehicle charger of this embodiment adopts all the technical solutions of all the above embodiments, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be described in detail here.

[0067] The above are only some embodiments of this application and do not limit the scope of protection of this application. All equivalent structural transformations made under the technical concept of this application and using the content of this application specification and drawings, or direct / indirect applications in other related technical fields, are included in the scope of protection of this application.

Claims

1. A charging circuit for an on-board charger, characterized in that, The system includes a main switching module, a pre-stage conversion module, a bus capacitor module, and a post-stage isolation module connected in sequence; a loop switching module connected to the bus capacitor module and the main switching module respectively; and a control module connected to the main switching module, the pre-stage conversion module, the post-stage isolation module, and the loop switching module respectively; wherein, the main switching module includes a three-phase main switch, and the loop switching module includes a loop switch; The control module controls the three-phase main switch, enabling the main switching module to switch between a three-phase connection mode and a single-phase connection mode, and controls the on / off state of the circuit switch, so that the charging circuit operates in a three-phase charging / discharging mode, a single-phase charging / discharging mode, or a split-phase charging / discharging mode; wherein, in the three-phase charging / discharging mode, the main switching module switches to the three-phase connection mode and the circuit switch is turned on; in the single-phase charging / discharging mode, the main switching module switches to the single-phase connection mode and the circuit switch is turned off; in the split-phase charging / discharging mode, the main switching module switches to the three-phase connection mode and the circuit switch is turned off.

2. The charging circuit of the on-board charger as described in claim 1, characterized in that, The three-phase main switch includes a first main switch, a second main switch, and a third main switch; The first terminal of the first main switch is connected to the first AC terminal of the AC charging / discharging interface, the second terminal of the first main switch is connected to the first AC terminal of the pre-conversion module, the first terminal of the second main switch is connected to the second AC terminal of the AC charging / discharging interface, the second terminal of the second main switch is connected to the second AC terminal of the pre-conversion module, the first terminal of the third main switch is connected to the third AC terminal of the AC charging / discharging interface, the second terminal of the third main switch is connected to the third AC terminal of the pre-conversion module, and the control terminals of the first main switch, the second main switch, and the third main switch are all connected to the control module.

3. The charging circuit of the on-board charger as described in claim 2, characterized in that, The front-end conversion module includes a three-phase four-wire bridge circuit; The first AC terminal of the three-phase four-wire bridge circuit is connected to the second terminal of the first main switch; the second AC terminal of the three-phase four-wire bridge circuit is connected to the second terminal of the second main switch; the third AC terminal of the three-phase four-wire bridge circuit is connected to the second terminal of the third main switch; the fourth AC terminal of the three-phase four-wire bridge circuit is connected to the fourth AC terminal of the AC charging and discharging interface; the first DC terminal of the three-phase four-wire bridge circuit is connected to the first terminal of the bus capacitor module; the second DC terminal of the three-phase four-wire bridge circuit is connected to the second terminal of the bus capacitor module; and the control terminals of each power device in the three-phase four-wire bridge circuit are all connected to the control module.

4. The charging circuit of the on-board charger as described in claim 3, characterized in that, The control module is also used for: Based on the dual closed-loop control method of three-dimensional spatial vector modulation and synchronous rotating coordinate system, the power devices in the three-phase four-wire bridge circuit are controlled to enable the front-end conversion module to perform three-phase charging and discharging or split-phase charging and discharging, so that the charging circuit works in the three-phase charging and discharging mode or the split-phase charging and discharging mode. or, Based on the sinusoidal pulse width modulation method and the dual closed-loop control method of synchronous rotating coordinate system, the power devices in the three-phase four-wire bridge circuit are controlled to enable the front-end conversion module to perform single-phase charging and discharging, so that the charging circuit operates in the single-phase charging and discharging mode.

5. The charging circuit of the on-board charger as described in claim 3, characterized in that, The circuit switching module also includes a first capacitor, a second capacitor, a third capacitor, and a fourth capacitor; One end of the first capacitor is connected to the second end of the first main switch, one end of the second capacitor is connected to the second end of the second main switch, one end of the third capacitor is connected to the second end of the third main switch, one end of the fourth capacitor is connected to the fourth AC terminal of the AC charging and discharging interface, the other ends of the first capacitor, the second capacitor, the third capacitor, and the fourth capacitor are all connected to the first end of the circuit switch, the second end of the circuit switch is connected to the third end of the bus capacitor module, and the control terminal of the circuit switch is connected to the control module.

6. The charging circuit of the on-board charger as described in claim 2, characterized in that, It also includes a pre-charge module; The pre-charge module includes a first pre-charge unit, a second pre-charge unit, and a third pre-charge unit. The first pre-charge unit is connected in parallel with the first main switch, the second pre-charge unit is connected in parallel with the second main switch, and the third pre-charge unit is connected in parallel with the third main switch. The first pre-charge unit is used to provide current limiting protection for the first main switch; The second pre-charge unit is used to provide current limiting protection for the second main switch; The third pre-charge unit is used to provide current limiting protection for the third main switch.

7. The charging circuit of the on-board charger as described in claim 1, characterized in that, The downstream isolation module includes a DC-DC conversion circuit, which is connected to the control module, the bus capacitor module, and the DC charging / discharging interface, respectively. The DC-DC conversion circuit is used to perform voltage conversion processing on the first initial DC voltage input to the bus capacitor module according to the voltage conversion control signal sent by the control module, to obtain a first target DC voltage for output through the DC charging and discharging interface, or to perform voltage conversion processing on the second initial DC voltage input to the DC charging and discharging interface to obtain a second target DC voltage for storage through the bus capacitor module.

8. The charging circuit of the on-board charger as described in claim 7, characterized in that, It also includes a DC filter module, which is connected to the DC-DC conversion circuit and the DC charging / discharging interface, respectively. The DC filtering module is used to perform electromagnetic interference suppression processing on the first target DC voltage input to the DC-DC conversion circuit, obtain a filtered first target DC voltage and provide it to the DC charging and discharging interface, or to perform electromagnetic interference suppression processing on the second initial DC voltage input to the DC charging and discharging interface, obtain a filtered second initial DC voltage and provide it to the DC-DC conversion circuit.

9. The charging circuit of the on-board charger as described in any one of claims 1 to 6, characterized in that, It also includes an AC filtering module, which is connected to the main switching module and the front-end conversion module, respectively; The AC filtering module is used to perform battery interference suppression processing on the first initial AC voltage input to the main switching module to obtain a first target AC voltage and provide it to the front-end conversion module, or to perform electromagnetic interference suppression processing on the second initial AC voltage input to the front-end conversion module to obtain a second target AC voltage and provide it to the main switching module.

10. An on-board charger, characterized in that, The charging circuit includes the on-board charger as described in any one of claims 1 to 9.

Images