Charging system and charging device

Abstract

The embodiment of the utility model provides a charging system and charging equipment. The charging system comprises a DC bus, an AC-DC conversion circuit, a DC-DC conversion circuit, a plurality of power supply circuits and an inductor group. Wherein the AC-DC conversion circuit is used for converting received alternating current into direct current and outputting the direct current to the DC-DC conversion circuit through a direct current bus. Each power supply circuit comprises a direct-current power supply and a ground capacitor, the direct-current power supply is connected with the direct-current bus through the ground capacitor, and the direct-current power supply is used for outputting direct current to the DC-DC conversion circuit through the direct-current bus. And the DC-DC conversion circuit is used for performing power conversion on the direct current obtained from the direct current bus and then outputting the direct current. In addition, the direct current bus is connected with the AC-DC conversion circuit through the inductor group, or the direct current bus is connected with each power supply circuit through the inductor group. According to the embodiment of the invention, the operation reliability of the charging system when the DC bus is connected with the plurality of power supply circuits can be improved.

Description

Technical Field

[0001] This application relates to the field of charging, and more specifically, to a charging system and charging device. Background Technology

[0002] With the rapid popularization of electric vehicles, the application of charging equipment as a supporting facility is also becoming more and more widespread. Among them, charging equipment often adopts an architecture design that uses an alternating current-to-direct current (AC-DC) conversion circuit connected to a direct current-to-direct current (DC-DC) conversion circuit via a DC bus, thereby connecting to the electric vehicle through the DC-DC conversion circuit.

[0003] Currently, to meet the charging needs of more electric vehicles, an increasing number of charging devices are connecting energy storage systems to the DC bus, enabling the DC bus to transmit the electrical energy output from the energy storage system to the electric vehicle via a DC-DC conversion circuit. However, in current practical applications, the DC bus is usually connected to the ground capacitor in the energy storage system. This means that as the number of energy storage systems connected to the DC bus increases, the total capacitance of the ground capacitor connected to the DC bus also increases accordingly. An excessively large total capacitance can easily increase the leakage current in the AC-DC conversion circuit and the circuit containing the DC bus, leading to filter saturation in the AC-DC conversion circuit and affecting the operational reliability of the charging equipment. Utility Model Content

[0004] This application provides a charging system and charging device that can reduce leakage current in the AC-DC conversion circuit formed by the DC bus and the ground capacitance of the multiple power circuits when multiple power circuits are connected to a DC bus. Furthermore, it can prevent the filter in the AC-DC conversion circuit from easily saturating due to multiple power circuits being connected to a DC bus, thereby improving the operational reliability of the charging system when multiple power circuits are connected to a DC bus.

[0005] Firstly, a charging system is provided, comprising a DC bus, an AC-DC conversion circuit, a DC-DC conversion circuit, and multiple power supply circuits. The AC-DC conversion circuit converts received alternating current (AC) into direct current (DC) and outputs it to the DC-DC conversion circuit via the DC bus. Each power supply circuit includes a DC power source and a capacitor to ground. The DC power source is connected to the DC bus via the capacitor to ground and outputs DC power to the DC-DC conversion circuit via the DC bus. The DC-DC conversion circuit performs power conversion on the DC power received from the DC bus and then outputs it. Furthermore, the charging system includes an inductor bank. The DC bus is connected to the AC-DC conversion circuit via the inductor bank, or the DC bus is connected to the capacitor to ground of each power supply circuit via the inductor bank.

[0006] Based on the above design, the inductor group can be connected in series in the grounding circuit formed by the DC bus and the ground capacitance of multiple power supply circuits in the AC-DC conversion circuit. In this way, by increasing the inductive reactance of the inductor group, the total impedance in the grounding circuit can be increased. Since the leakage current generated in the grounding circuit is negatively correlated with the total impedance, the leakage current in the grounding circuit can be reduced. Furthermore, this prevents the filter in the AC-DC conversion circuit from easily saturating due to multiple power supply circuits connected to the DC bus, thereby ensuring the operational reliability of the charging system when multiple power supply circuits are connected to the DC bus.

[0007] In one implementation, there are multiple AC-DC conversion circuits and one set of inductor groups. The multiple AC-DC conversion circuits are connected in parallel to a DC bus, and the DC bus is connected to the ground capacitance of each power supply circuit through the set of inductor groups.

[0008] Based on the above design, a group of inductors can be connected in series between the DC bus and multiple power supply circuits. By flexibly adjusting the inductive reactance of the inductors in this group, the leakage current in the grounding circuit formed by any AC-DC conversion circuit in the charging system through the DC bus and multiple power supply circuits can be reduced. This prevents the filter in any AC-DC conversion circuit in the charging system from easily saturating due to multiple power supply circuits being connected to the DC bus.

[0009] In one implementation, there are multiple AC-DC conversion circuits and multiple sets of inductors. One AC-DC conversion circuit is connected to the DC bus via a set of inductors.

[0010] Based on the above design, a set of inductors can be connected in series between each AC-DC conversion circuit in the charging system and the DC bus. By flexibly adjusting the inductive reactance of the inductors in the set connected in series with any AC-DC conversion circuit, the leakage current generated in the grounding circuit formed by the DC bus and multiple power supply circuits of that AC-DC conversion circuit can be reduced. This prevents the filter in any AC-DC conversion circuit from easily saturating due to multiple power supply circuits connected to the DC bus. Furthermore, each set of inductors can be used only to adjust the leakage current in the grounding circuit of the AC-DC conversion circuit it is connected to. Compared to adjusting the leakage current of the grounding circuit of multiple AC-DC conversion circuits in the charging system using a single set of inductors, this reduces the current-carrying capacity requirement of each set of inductors and reduces the size of the inductors used.

[0011] In one implementation, the charging system further includes a leakage current detection circuit and a switching circuit connected in series. The DC bus is connected to the ground capacitance of each power supply circuit through the series-connected leakage current detection circuit and switching circuit. The leakage current detection circuit is used to detect the ground current of the circuit formed by the DC bus and the ground capacitances of the multiple power supply circuits. The switching circuit is used to disconnect the circuit between the DC bus and the ground capacitances of the multiple power supply circuits when the ground current detected by the leakage current detection circuit is greater than a preset current.

[0012] Based on the above design, the DC bus can be connected to each power supply circuit in the charging system through a set of series leakage current detection circuits and switching circuits. This allows for timely disconnection of the circuit between the DC bus and multiple power supply circuits when the leakage current in the grounding circuit formed by the DC bus and the ground capacitance of multiple power supply circuits is large, thereby achieving ground insulation protection for the DC bus and improving the operational safety of the charging system.

[0013] In one implementation, the charging system further includes multiple leakage current detection circuits and multiple switching circuits. One leakage current detection circuit is connected in series with one switching circuit. The DC bus is connected to the ground capacitance of a power supply circuit via the series-connected leakage current detection circuit and the switching circuit. One leakage current detection circuit detects the ground current in the circuit formed by the DC bus and the ground capacitance in the power supply circuit. One switching circuit disconnects the circuit between the DC bus and the power supply circuit when the ground current detected by the leakage current detection circuit exceeds a preset current.

[0014] Based on the above design, each power circuit in the charging system can be connected to the DC bus through a set of series leakage current detection circuits and switching circuits. This allows for timely disconnection of the DC bus from any power circuit when a large leakage current occurs in the grounding circuit formed by the DC bus and the ground capacitance of any power circuit. This achieves precise fault isolation, provides ground insulation protection for the DC bus, and improves the operational safety of the charging system.

[0015] In one implementation, the preset current is less than or equal to 6A.

[0016] In one implementation, the charging system further includes a ground insulation impedance detection circuit and a switching circuit. The DC bus is connected to one end of the ground insulation impedance detection circuit via the switching circuit, and the other end of the ground insulation impedance detection circuit is connected to the ground capacitor of each power supply circuit. The ground insulation impedance detection circuit is used to detect the ground insulation impedance of the circuit containing the multiple power supply circuits before the AC-DC conversion circuit and the multiple power supply circuits are started. The switching circuit is used to connect the DC bus to the ground capacitor in the multiple power supply circuits before the AC-DC conversion circuit and the multiple power supply circuits are started, when the ground insulation impedance detected by the ground insulation impedance detection circuit is greater than a preset insulation impedance.

[0017] Based on the above design, the DC bus can be connected to each power circuit in the charging system via a set of series-connected switching circuits and a ground insulation resistance detection circuit. Before the AC-DC conversion circuit and multiple power circuits are started, the charging system can first disconnect the circuit between the DC bus and the multiple power circuits via the switching circuits. Then, when the ground insulation resistance of the circuits containing the multiple power circuits is high, the circuit between the DC bus and the multiple power circuits can be reconnected via the switching circuits. This prevents safety issues caused by forcibly connecting multiple power circuits to the DC bus when the ground insulation resistance of the circuits containing the multiple power circuits is abnormal. Furthermore, it achieves ground insulation protection for the DC bus, improving the operational safety of the charging system.

[0018] In one implementation, the charging system further includes multiple ground insulation resistance detection circuits and multiple switching circuits. The DC bus is connected to one end of a ground insulation resistance detection circuit via a switching circuit, and the other end of the ground insulation resistance detection circuit is connected to a ground capacitor in a power supply circuit. The ground insulation resistance detection circuit is used to detect the ground insulation resistance of the circuit containing the power supply circuit before the AC-DC conversion circuit and the power supply circuit are started. The switching circuit is used to connect the DC bus to the ground capacitor in the power supply circuit when the ground insulation resistance detected by the ground insulation resistance detection circuit is greater than a preset insulation resistance before the AC-DC conversion circuit and the power supply circuit are started.

[0019] Based on the above design, each power circuit in the charging system can be connected to the DC bus through a set of series-connected switching circuits and a ground insulation impedance detection circuit. Before the AC-DC conversion circuit and any power circuit are started, the charging system can first disconnect the circuit between the DC bus and that power circuit via the switching circuit connected to that power circuit. Then, when the ground insulation impedance of the circuit containing that power circuit is high, the switching circuit can be used to reconnect the circuit between the DC bus and that power circuit. This prevents safety issues caused by forcibly connecting any power circuit to the DC bus when its ground insulation impedance is abnormal. Furthermore, precise fault isolation can be achieved to provide ground insulation protection for the DC bus, improving the operational safety of the charging system.

[0020] In one implementation, the preset ground insulation impedance is less than or equal to m×V. bus / 30mA. Where 0.8≤m≤1.0, V bus This is the rated operating voltage of the DC bus.

[0021] In one implementation, the charging system further includes a fuse bank. The DC bus is connected to the ground capacitance of each power circuit via the fuse bank.

[0022] Based on the above design, the fuse group can disconnect the DC bus from multiple power circuits by melting when the current flowing through it is large, so as to prevent the circuit fault from spreading and thus further improve the operational stability of the charging system.

[0023] Secondly, a charging device is provided, comprising a DC bus, an AC-DC conversion circuit, and a DC-DC conversion circuit. The AC-DC conversion circuit converts received AC power into DC power, which is then output to the DC-DC conversion circuit via the DC bus. The DC bus connects the ground capacitance of each of multiple power circuits and transmits the DC power output from the ground capacitance of each power circuit to the DC-DC conversion circuit. The DC-DC conversion circuit performs power conversion on the DC power received from the DC bus and outputs it. The charging device also includes an inductor bank; the DC bus connects to the AC-DC conversion circuit via the inductor bank, or the DC bus connects to the ground capacitance of each power circuit via the inductor bank.

[0024] In one implementation, there are multiple AC-DC conversion circuits and one set of inductor groups. The multiple AC-DC conversion circuits are connected in parallel to a DC bus, which is used to connect the ground capacitance of each power supply circuit through the set of inductor groups.

[0025] In one implementation, there are multiple AC-DC conversion circuits and multiple sets of inductors. One AC-DC conversion circuit is connected to the DC bus via a set of inductors.

[0026] In one implementation, the charging device further includes a leakage current detection circuit and a switching circuit connected in series. The DC bus is used to connect the ground capacitance of each power circuit through the series-connected leakage current detection circuit and switching circuit. The leakage current detection circuit is used to detect the ground current of the circuit formed by the DC bus and the ground capacitances of the multiple power circuits. The switching circuit is used to disconnect the circuit between the DC bus and the ground capacitances of the multiple power circuits when the ground current detected by the leakage current detection circuit is greater than a preset current.

[0027] In one implementation, the charging device further includes multiple leakage current detection circuits and multiple switching circuits. One leakage current detection circuit is connected in series with one switching circuit. The DC bus is used to connect a power supply circuit's ground capacitance via the series-connected leakage current detection circuit and switching circuit. One leakage current detection circuit detects the ground current in the circuit formed by the DC bus and the ground capacitance in the power supply circuit. A switching circuit disconnects the circuit between the DC bus and the ground capacitance in the power supply circuit when the ground current detected by the leakage current detection circuit exceeds a preset current.

[0028] In one implementation, the preset current is less than or equal to 6A.

[0029] In one implementation, the charging device further includes a ground insulation impedance detection circuit and a switching circuit. The DC bus is connected to one end of the ground insulation impedance detection circuit via the switching circuit, and the other end of the ground insulation impedance detection circuit is connected to the ground capacitor of each power supply circuit. The ground insulation impedance detection circuit is used to detect the ground insulation impedance of the circuit containing the multiple power supply circuits before the AC-DC conversion circuit and the multiple power supply circuits are started. The switching circuit is used to connect the DC bus to the ground capacitor in the multiple power supply circuits when the ground insulation impedance detected by the ground insulation impedance detection circuit is greater than a preset insulation impedance before the AC-DC conversion circuit and the multiple power supply circuits are started.

[0030] In one implementation, the charging device further includes multiple ground insulation resistance detection circuits and multiple switching circuits. A DC bus is connected to one end of a ground insulation resistance detection circuit via a switching circuit, and the other end of the ground insulation resistance detection circuit is connected to a ground capacitor in a power supply circuit. The ground insulation resistance detection circuit is used to detect the ground insulation resistance of the circuit containing the power supply circuit before the AC-DC conversion circuit and the power supply circuit are started. A switching circuit is used to connect the DC bus to the ground capacitor in the power supply circuit when the ground insulation resistance detected by the ground insulation resistance detection circuit is greater than a preset insulation resistance before the AC-DC conversion circuit and the power supply circuit are started.

[0031] In one implementation, the preset ground insulation impedance is less than or equal to m×V. bus / 30mA. Where 0.8≤m≤1.0, V bus This is the rated operating voltage of the DC bus.

[0032] In one implementation, the charging device further includes a fuse bank. The DC bus is connected to the ground capacitance of each power circuit via the fuse bank.

[0033] For details regarding the beneficial effects not elaborated in the second aspect, please refer to the beneficial effects in the first aspect above, which will not be repeated here. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of a charging device for charging an electric vehicle, as provided in an embodiment of this application.

[0035] Figure 2 This is an example provided in the embodiments of this application. Figure 1 The circuit structure diagram of the charging device shown is shown.

[0036] Figure 3 This is a schematic diagram of a charging system provided in an embodiment of this application.

[0037] Figure 4 and Figure 5 These are one of the embodiments provided in this application. Figure 3 The diagram shows the specific structure of the charging system.

[0038] Figures 6 to 9 These are examples provided in the embodiments of this application. Figure 4 The diagram shows the specific structure of the charging system. Detailed Implementation

[0039] To facilitate understanding of the embodiments of this application, the following points will be explained before introducing the embodiments of this application.

[0040] In the description of the embodiments of this application, "connection" can refer to an electrical connection. An electrical connection can be understood as the transmission of signals between two electrical components through a direct or indirect electrical connection. For example, an electrical connection between A and B can be understood as a direct electrical connection between A and B, or an indirect electrical connection between A and B through one or more other electrical components.

[0041] In the embodiments of this application, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, features defined as "first" or "second" may explicitly or implicitly include one or more features. Furthermore, in the description of the embodiments of this application, "multiple" refers to two or more, and "at least one" and "one or more" refer to one, two, or more than two.

[0042] In the description of the embodiments of this application, unless otherwise stated, "and / or" is merely a description of the relationship between related objects, indicating that there can be three relationships. For example, A and / or B can represent three situations: A exists alone, A and B exist simultaneously, and B exists alone.

[0043] The technical solutions in this application will now be described with reference to the accompanying drawings.

[0044] First, to facilitate understanding of the technical solutions provided in the embodiments of this application, we will introduce the application scenarios applicable to the embodiments of this application.

[0045] Figure 1 This is a schematic diagram of a scenario where a charging device 10 charges an electric vehicle 20, as provided in an embodiment of this application.

[0046] See Figure 1 The charging device 10 receives AC power from the grid 30 and converts it into stable DC power before supplying it to the electric vehicle 20 to charge it. Alternatively, the electric vehicle 20 can also output electrical energy back to the grid 30 via the charging device 10.

[0047] For example, such as Figure 1As shown, the charging device 10 is a split-type charging device. Specifically, the charging device 10 includes a charging host 11, multiple charging terminals 12, and multiple charging guns 13. The charging host 11 includes multiple power conversion circuits that convert the AC power output from the power grid 30 into stable DC power before outputting it to each charging terminal 12. Each charging terminal 12 is used to mount at least one charging gun 13. Each charging gun 13 is used to transmit the DC power output from the multiple power conversion circuits to the charging terminal 12 to the electric vehicle 20 for charging. In a specific implementation, an electric vehicle 20 can be connected to one or more charging guns 13.

[0048] It should be understood that, in the embodiments of this application, the charging terminal 12 may include a cabinet, a human-machine interface, a charging control unit, and a metering and billing unit, etc., for information interaction, energy transmission, and metering and billing with the electric vehicle 20.

[0049] It should also be understood that, in the embodiments of this application, the electric vehicle 20 is a means of transportation driven by electric power. The electric vehicle 20 is a pure electric vehicle (pure EV / battery EV), a hybrid electric vehicle (HEV), a range-extended electric vehicle (REEV), or a plug-in hybrid electric vehicle (PHEV), etc.

[0050] The following section provides a further description of the multiple power conversion circuits located in the charging host 11 mentioned above.

[0051] Figure 2 This is an example provided in the embodiments of this application. Figure 1 The circuit structure diagram of the charging device 10 shown is shown.

[0052] In some embodiments, see Figure 2The charging host 11 includes multiple power conversion circuits, including multiple AC-DC conversion circuits 111 and multiple DC-DC conversion circuits 112. The charging host 11 also includes a DC bus 113 and a power distribution matrix 114. The A-phase, B-phase, and C-phase input terminals of each AC-DC conversion circuit 111 are connected to the power grid 30. The output terminal of each AC-DC conversion circuit 111 is connected to the input terminal of each DC-DC conversion circuit 112 via the positive DC bus Bus+ and the negative DC bus Bus- of the DC bus 113. The output terminal of each DC-DC conversion circuit 112 is connected to the charging gun 13 in each charging terminal 12 via the power distribution matrix 114.

[0053] In practical implementation, each AC-DC conversion circuit 111 converts the AC power output from the power grid 30 into DC power and outputs it to the DC bus 113. Each DC-DC conversion circuit 112 further converts the DC power obtained from the DC bus 113 into DC power suitable for the electric vehicle 20 and outputs it to the power distribution matrix 114. The power distribution matrix 114 is used to connect the circuit between the output terminal of any DC-DC conversion circuit 112 and the charging gun 13 in any charging terminal 12, so as to realize the dynamic distribution of power among the multiple DC-DC conversion circuits 112 and multiple charging guns 13 in the charging equipment 10, so that the power output by the charging gun 13 to the electric vehicle 20 can meet the charging needs of the electric vehicle 20.

[0054] As described in the background section above, with the increasing charging demand of electric vehicles 20, more and more charging devices 10 are adopting a DC-DC cascaded energy storage architecture. That is, by connecting the energy storage system 40 to the DC bus 113, the DC power output by the energy storage system 40 is transmitted to the DC-DC conversion circuit 112 through the DC bus 113. In this way, the DC-DC conversion circuit 112 can flexibly schedule the power of the grid 30 and the energy storage power to meet the charging power demand of electric vehicles 20 and achieve peak shaving and valley filling effects.

[0055] Currently, the energy storage system 40 generally includes an energy storage battery 41 and a DC-DC conversion circuit 42. The DC-DC conversion circuit 42 converts the DC power output from the energy storage battery 41 into power and outputs it to the DC-DC conversion circuit 112 via the DC bus 113. Furthermore, to filter out high-frequency common-mode interference, the DC-DC conversion circuit 42 is generally connected to the DC bus 113 via a ground capacitor installed in the energy storage system 40. For example, as... Figure 2As shown, the energy storage system 40 also includes ground capacitors CY1 and CY2. The positive and negative output terminals of the DC-DC conversion circuit 42 are respectively connected to the positive DC bus Bus+ and the negative DC bus Bus- through one end of ground capacitor CY1 and one end of ground capacitor CY2. The other ends of ground capacitors CY1 and CY2 are connected to the ground wire (protecting earthing, PE).

[0056] However, when the AC-DC conversion circuit 111 is a non-isolated AC-DC conversion circuit, that is, when there is no electrical isolation between the input and output of the AC-DC conversion circuit 111, as the number of energy storage systems 40 connected to the DC bus 113 increases, the total capacitance of the capacitors connected to ground connected to the DC bus 113 increases accordingly. For example, as the number of connected energy storage systems 40 increases, the number of capacitors CY1 connected to ground connected to the positive DC bus Bus+ also increases, and the total capacitance of the capacitors connected to ground connected to the positive DC bus Bus+ increases. Correspondingly, the total capacitive reactance of the capacitors connected to ground connected to the positive DC bus Bus+ decreases. This leads to a decrease in the total impedance in the grounding loop formed by the AC-DC conversion circuit 111 through the positive DC bus Bus+, the capacitors CY1 in the energy storage system 40, and the ground wire PE. Correspondingly, the ground current in the grounding loop increases, that is, the leakage current of the AC-DC conversion circuit 111 and the circuit containing the positive DC bus Bus+ increases. The increased leakage current can easily cause the filter in the AC-DC conversion circuit 111 to saturate, thereby affecting the normal operation of the charging device 10.

[0057] Based on the above, this application provides a charging system including a DC bus, an AC-DC conversion circuit, a DC-DC conversion circuit, and multiple power supply circuits. The AC-DC conversion circuit converts received AC power into DC power, which is then output to the DC-DC conversion circuit via the DC bus. Each power supply circuit includes a DC power source and a capacitor to ground. The DC power source is connected to the DC bus via the capacitor to ground and outputs DC power to the DC-DC conversion circuit via the DC bus. The DC-DC conversion circuit converts the DC power received from the DC bus and outputs it. Furthermore, the charging system includes an inductor bank. The DC bus is connected to the AC-DC conversion circuit via the inductor bank, or the DC bus is connected to the capacitor to ground of each power supply circuit via the inductor bank.

[0058] Based on the above design, the inductor group can be connected in series in the grounding circuit formed by the DC bus and the ground capacitance of multiple power supply circuits in the AC-DC conversion circuit. In this way, by increasing the inductive reactance of the inductor group, the total impedance in the grounding circuit can be increased. Since the leakage current generated in the grounding circuit is negatively correlated with the total impedance, the leakage current in the grounding circuit can be reduced. Furthermore, this prevents the filter in the AC-DC conversion circuit from easily saturating due to multiple power supply circuits connected to the DC bus, thereby ensuring the operational reliability of the charging system when multiple power supply circuits are connected to the DC bus.

[0059] The charging system provided in the embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0060] Figure 3 This is a schematic diagram of the structure of a charging system 50 provided in an embodiment of this application.

[0061] In some embodiments, see Figure 3 The charging system 50 includes an AC-DC conversion circuit 51, a DC bus 52, and a first DC-DC conversion circuit 53. The A-phase, B-phase, and C-phase input terminals of the AC-DC conversion circuit 51 are connected to an AC power source, such as the power grid. The output terminal of the AC-DC conversion circuit 51 is connected to the input terminal of the first DC-DC conversion circuit 53 via the positive DC bus Bus+ and the negative DC bus Bus- in the DC bus 52. The output terminal of the first DC-DC conversion circuit 53 is used to connect to an electric vehicle.

[0062] It should be understood that in this embodiment, the number of AC-DC conversion circuit 51 and the number of first DC-DC conversion circuit 53 can each be multiple. Multiple AC-DC conversion circuits 51 are connected in parallel to the DC bus 52, and multiple first DC-DC conversion circuits 53 are also connected in parallel to the DC bus 52. For a detailed description of the AC-DC conversion circuit 51, the DC bus 52, and the first DC-DC conversion circuit 53, please refer to... Figure 2 The relevant descriptions of the AC-DC conversion circuit 111, DC-DC conversion circuit 112, and DC bus 113 shown are not repeated here.

[0063] In some embodiments, see Figure 3 The charging system 50 also includes multiple power supply circuits 54, which are connected in parallel to the DC bus 52. Specifically, each power supply circuit 54 includes a DC power supply and a capacitor to ground. The DC power supply is connected to the DC bus 52 through the capacitor to ground, and the DC power supply is used to output DC power to the first DC-DC conversion circuit 53 through the DC bus 52, so that the first DC-DC conversion circuit 53 can deliver the DC power output by the DC power supply to the electric vehicle.

[0064] It should be understood that in this embodiment, the power supply circuit 54 can be an energy storage system, and the corresponding DC power supply is an energy storage battery. Alternatively, the power supply circuit 54 can also be a photovoltaic system, and the corresponding DC power supply is a photovoltaic module. When the power supply circuit 54 is an energy storage system, the DC power supply in the energy storage system 54 can also obtain DC power output from the AC-DC conversion circuit 51 through the DC bus 52 for charging.

[0065] For example, such as Figure 3 As shown, taking the charging system 50, which includes power supply circuits 54a and 54b, as an example, power supply circuit 54a includes a DC power supply 541a, a second DC-DC conversion circuit 542a, a ground capacitor CY1, and a ground capacitor CY2. The input terminal of the second DC-DC conversion circuit 542a is connected to the DC power supply 541a. The positive output terminal of the second DC-DC conversion circuit 542a is connected to the positive DC bus Bus+ in the DC bus 52 through one end of the ground capacitor CY1. The negative output terminal of the second DC-DC conversion circuit 542a is connected to the negative DC bus Bus- in the DC bus 52 through one end of the ground capacitor CY2. The other ends of the ground capacitors CY1 and CY2 are connected to the ground wire PE. The second DC-DC conversion circuit 542a is used to convert the DC power output from the DC power supply 541a into voltage and then output it to the first DC-DC conversion circuit 53 through the DC bus 52.

[0066] It should be understood that, in the embodiments of this application, when the power supply circuit 54a is an energy storage system, the second DC-DC conversion circuit 542a can also be used to obtain the DC power output by the AC-DC conversion circuit 51 through the DC bus 52, and output the DC power to the DC power supply 541a after voltage conversion, so as to charge the DC power supply 541a.

[0067] Similarly, power supply circuit 54b includes a DC power supply 541b, a second DC-DC conversion circuit 542b, and capacitors CY3 and CY4 connected to ground. The positive and negative output terminals of the second DC-DC conversion circuit 542b are connected to the positive DC bus Bus+ and negative DC bus Bus- of DC bus 52 respectively through one end of capacitor CY3 and one end of capacitor CY4. The other ends of capacitors CY3 and CY4 are connected to ground wire PE. For a detailed description of power supply circuit 54b, please refer to the description of power supply circuit 54a above; it will not be repeated here.

[0068] Based on the above design, the first DC-DC conversion circuit 53 can not only schedule the power output of the AC power supply, but also schedule the energy storage power and / or photovoltaic power in the multiple power circuits 54 connected to the DC bus 52 to charge the electric vehicle, thereby realizing flexible scheduling of mains power, solar energy and energy storage power to meet the charging needs of the electric vehicle.

[0069] In some embodiments, see Figure 3 The charging system 50 also includes an inductor group 55. The DC bus 52 is connected to the AC-DC conversion circuit 51 via the inductor group 55, or the DC bus 52 is connected to the ground capacitor of each power circuit 54 in the charging system 50 via the inductor group 55.

[0070] For example, such as Figure 3 As shown, taking the DC bus 52 connected to the ground capacitors in power circuit 54a and 54b via inductor group 55 as an example, inductor group 55 includes inductor L1 and inductor L2. The positive DC bus Bus+ in DC bus 52 is connected to the ground capacitors CY1 and CY3 in power circuit 54a via inductor L1. The negative DC bus Bus- in DC bus 52 is connected to the ground capacitors CY2 and CY4 in power circuit 54b via inductor L2.

[0071] Based on the above design, inductor L1 is connected in series in the grounding circuit formed by the AC-DC conversion circuit 51 through the positive DC bus Bus+, the grounding capacitor CY1 in the power supply circuit 54a, and the grounding capacitor CY3 in the power supply circuit 54b. Thus, the inductive reactance of inductor L1 is positively correlated with the total impedance of the AC-DC conversion circuit 51 and the grounding circuit containing the positive DC bus Bus+. In other words, as the inductive reactance of inductor L1 increases, the total impedance of the AC-DC conversion circuit 51 and the grounding circuit containing the positive DC bus Bus+ also increases.

[0072] It should be understood that the aforementioned ground capacitors CY1 and CY3 are connected in parallel to the AC-DC conversion circuit 51 and the grounding circuit containing the positive DC bus Bus+. The parallel connection of these two ground capacitors increases the total capacitance of the ground capacitors connected to the positive DC bus Bus+, correspondingly decreasing the total capacitive reactance of the ground capacitors connected to the positive DC bus Bus+. This results in a decrease in the total impedance of the AC-DC conversion circuit 51 and the grounding circuit containing the positive DC bus Bus+. Since the leakage current generated in the grounding circuit is equal to the common-mode voltage at any phase input terminal of the AC-DC conversion circuit 51 divided by the total impedance in the grounding circuit, the leakage current generated in the grounding circuit increases as the total impedance in the grounding circuit decreases.

[0073] Based on the above analysis, embodiments of this application can increase the inductive reactance of inductor L1 to increase the total impedance in the grounding circuit where the AC-DC conversion circuit 51 and the positive DC bus Bus+ are located, thereby reducing the leakage current generated in the grounding circuit and alleviating the problem of increased leakage current in the grounding circuit caused by the parallel connection of ground capacitors CY1 and CY3. Similarly, embodiments of this application can also increase the inductive reactance of inductor L2 to increase the total impedance of the grounding circuit formed by the AC-DC conversion circuit 51 through the negative DC bus Bus-, the ground capacitor CY2 in the power supply circuit 54a, and the ground capacitor CY4 in the power supply circuit 54b, thereby reducing the leakage current generated in the grounding circuit.

[0074] Therefore, when multiple power supply circuits 54 are connected to the DC bus 52, by setting an inductor group 55 in series in the grounding circuit formed by the DC bus 52 and the grounding capacitors in the multiple power supply circuits 54, and flexibly adjusting the inductive reactance of the inductors in the inductor group 55, the leakage current generated in the grounding circuit can be reduced. Furthermore, this prevents the filter in the AC-DC conversion circuit 51 from easily saturating due to multiple power supply circuits 54 being connected to the DC bus 52, thereby ensuring the operational reliability of the charging system 50 when multiple power supply circuits 54 are connected to the DC bus 52.

[0075] The following section will further introduce the specific configuration of the inductor group 55 in the charging system 40.

[0076] Figure 4 This is one of the embodiments provided in this application. Figure 3 The schematic diagram of the charging system 50 shown is shown.

[0077] In some embodiments, see Figure 4 In the charging system 50, multiple AC-DC conversion circuits 51 and multiple first DC-DC conversion circuits 53 are connected in parallel to the DC bus 52. Furthermore, the charging system 50 has a set of inductor groups 55, through which the DC bus 52 connects the ground capacitance of each of the multiple power circuits 54.

[0078] For example, such as Figure 4As shown, taking the charging system 50, which includes power supply circuits 54a and 54b, as an example, the charging system 50 also includes AC-DC conversion circuits 51a and 51b, a first DC-DC conversion circuit 53a, a first DC-DC conversion circuit 53b, and an inductor group 55a. The outputs of AC-DC conversion circuits 51a and 51b are connected in parallel to the DC bus 52, and the inputs of the first DC-DC conversion circuits 53a and 53b are connected in parallel to the DC bus 52. Furthermore, the positive DC bus Bus+ and negative DC bus Bus- in the DC bus 52 are connected to the ground capacitors in the power supply circuits 54a and 54b respectively through inductors L1a and L2a in the inductor group 55a. For a detailed description, please refer to [link to relevant documentation]. Figure 3 The relevant descriptions of the embodiments shown will not be repeated here.

[0079] Based on the above design, the inductor group 55a can be connected in series between the DC bus 52 and multiple power supply circuits 54. In this way, by flexibly adjusting the inductive reactance of the inductors in the inductor group 55a, the leakage current generated in the grounding circuit formed by any AC-DC conversion circuit 51 in the charging system 50 through the DC bus 52 and multiple power supply circuits 54 can be reduced. This can prevent the problem of easy saturation of the filter in any AC-DC conversion circuit 51 in the charging system 50 due to the connection of multiple power supply circuits 54 to the DC bus 52.

[0080] In some embodiments, see Figure 4 Taking the AC-DC conversion circuit 51a as an example, which forms a grounding circuit with the positive DC bus Bus+, the grounding capacitor CY1 in the power supply circuit 54a, and the grounding capacitor CY3 in the power supply circuit 54b, the leakage current I generated by this grounding circuit is... leak Satisfying the following equations (1) and (2):

[0081]

[0082] I leak ≤min(I sat I max (2)

[0083] Among them, V com This represents the maximum common-mode voltage among the common-mode voltages at the A-phase input, B-phase input, and C-phase input of the AC-DC converter circuit 51a. line Z represents the total impedance of all electronic components and transmission lines in the grounding circuit formed by the positive DC bus Bus+ and the ground capacitors CY1 and CY3 in the AC-DC conversion circuit 51a, excluding inductor L1 and the ground capacitors CY1 and CY3.L This represents the inductive reactance of inductor L1 in inductor group 55a. (C) y This represents the total capacitance of capacitors CY1 and CY3 to ground, which is equal to the sum of the capacitances of capacitors CY1 and CY3 to ground. 1 / ωC y This represents the equivalent capacitive reactance of the capacitances to ground CY1 and CY3. min(I sat I max ) indicates I sat and I max The minimum current in, I sat I represents the common-mode current saturation value of the filter in the AC-DC conversion circuit 51a. max This indicates the upper limit of the leakage current regulation capability in the AC-DC conversion circuit 51a.

[0084] Based on the above design, the leakage current generated in the grounding circuit formed by the positive DC bus Bus+, the ground capacitor CY1, and the ground capacitor CY3 at any phase input terminal of the AC-DC conversion circuit 51a can meet the requirements of the AC-DC conversion circuit 51a during normal operation.

[0085] It should also be understood that, in the embodiments of this application, the above-mentioned leakage current I leak The formula is applicable to the grounding circuit formed by any AC-DC conversion circuit 51 in the charging system 50.

[0086] Figure 5 This is another embodiment provided in this application. Figure 3 The schematic diagram of the charging system 50 shown is shown.

[0087] and Figure 4 The same as the illustrated embodiments is that, in Figure 5 In the embodiment shown, the multiple AC-DC conversion circuits 51 and the multiple first DC-DC conversion circuits 53 in the charging system 50 are connected in parallel to the DC bus 52.

[0088] and Figure 4 The difference between the illustrated embodiment and the one shown is that, in Figure 5 In the illustrated embodiment, the charging system 50 contains multiple sets of inductor groups 55. One AC-DC conversion circuit 51 is connected to the DC bus 52 via a set of inductor groups 55. In other words, the multiple AC-DC conversion circuits 51 and multiple sets of inductor groups 55 in the charging system 50 correspond one-to-one, with each AC-DC conversion circuit 51 connected to the DC bus 52 via its corresponding set of inductor groups 55.

[0089] For example, such as Figure 5As shown, taking the charging system 50, which includes AC-DC conversion circuit 51a and AC-DC conversion circuit 51b, as an example, the charging system 50 also includes inductor groups 55a and 55b. The positive and negative output terminals of the AC-DC conversion circuit 51a are connected to the positive DC bus Bus+ and negative DC bus Bus- of the DC bus 52 via inductors L1a and L2a in the inductor group 55a. The positive and negative output terminals of the AC-DC conversion circuit 51b are connected to the positive DC bus Bus+ and negative DC bus Bus- of the DC bus 52 via inductors L1b and L2b in the inductor group 55b.

[0090] Based on the above design, each AC-DC conversion circuit 51 in the charging system 50 can be connected in series with a set of inductors 55 to the DC bus 52. This allows for flexible adjustment of the inductive reactance of the inductors in the set of inductors 55 connected in series with any AC-DC conversion circuit 51, reducing the leakage current in the grounding circuit of that AC-DC conversion circuit 51. This prevents the filter in any AC-DC conversion circuit 51 from easily saturating due to multiple power supply circuits 54 connected to the DC bus 52. Furthermore, each set of inductors 55 can be used only to adjust the leakage current in the grounding circuit of the AC-DC conversion circuit 51 it is connected to. Compared to adjusting the leakage current in the grounding circuits of multiple AC-DC conversion circuits in the charging system 50 using a set of inductors 55, this reduces the current-carrying capacity requirement of each set of inductors 55 and reduces the size of the inductors used.

[0091] It should be understood that, in specific implementations, the magnitude of the leakage current generated in the grounding circuit of any AC-DC conversion circuit 51 in the charging system 50 and the inductive reactance of the corresponding inductor in the inductor group 55 can be found in [reference needed]. Figure 4 Regarding the leakage current I in the illustrated embodiment leak The relevant descriptions will not be repeated here.

[0092] The following is based on Figure 4 The charging system 50 shown includes a set of inductor groups 55, specifically inductor group 55a. Other structures within the charging system 50 will be described using this example. It should be understood that the following description of the charging system 50 also applies to... Figure 5 The charging system 50 shown includes multiple groups of inductors 55.

[0093] Figure 6 and Figure 7 These are examples provided in the embodiments of this application. Figure 4 The schematic diagram of the charging system 50 shown is shown.

[0094] In some embodiments, see Figure 6The charging system 50 also includes a leakage current detection circuit 56 and a switching circuit 57 connected in series. The DC bus 52 is connected to the ground capacitance of each of the multiple power supply circuits 54 through the series leakage current detection circuit 56 and the switching circuit 57. The leakage current detection circuit 56 detects the ground current in the circuit formed by the DC bus 52 and the ground capacitances of the multiple power supply circuits 54. The switching circuit 57 disconnects the circuit between the DC bus 52 and the multiple power supply circuits 54 when the ground current detected by the leakage current detection circuit 56 is greater than a preset current.

[0095] For example, such as Figure 6 As shown, taking the charging system 50 as an example, which includes AC-DC conversion circuit 51a, AC-DC conversion circuit 51b, power supply circuit 54a and power supply circuit 54b, AC-DC conversion circuit 51a and AC-DC conversion circuit 51b are connected in parallel to DC bus 52, and DC bus 52 is connected to power supply circuit 54a and power supply circuit 54b through leakage current detection circuit 56 and switching circuit 57 connected in series.

[0096] Taking the AC-DC conversion circuit 51a, power supply circuit 54a, and power supply circuit 54b all operating as an example, the leakage current detection circuit 56 can detect the current flowing into and out of the leakage current detection circuit 56, and use the difference between these two currents as the leakage current in the grounding circuit formed by the AC-DC conversion circuit 51a through the DC bus 52 and the grounding capacitors in the power supply circuits 54a and 54b. Furthermore, when the leakage current detected by the leakage current detection circuit 56 exceeds a preset current value, the charging system 50 can confirm that the insulation state of the grounding circuit where the DC bus 52 is located does not meet the conditions for safe operation, thereby causing the switching circuit 57 to disconnect the circuit between the DC bus 52 and the power supply circuits 54a and 54b.

[0097] Based on the above design, the DC bus 52 can be connected to each power circuit 54 in the charging system 50 through a set of series-connected leakage current detection circuits 56 and switching circuits 57. This allows for timely disconnection of the circuit between the DC bus 52 and the multiple power circuits 54 when the leakage current in the grounding circuit formed by any AC-DC conversion circuit 51 in the charging system 50 through the DC bus 52 and the grounding capacitors in the multiple power circuits 54 is large. This achieves ground insulation protection for the DC bus 52 and improves the operational safety of the charging system 50.

[0098] In some embodiments, see Figure 6The switching circuit 57 includes switches K1 and K2. The positive DC bus Bus+ and negative DC bus Bus- of the DC bus 52 can be connected to the ground capacitor in each power supply circuit 54 via switches K1 and K2, respectively. Thus, by closing or opening switches K1 and K2, the circuit between the DC bus 52 and the multiple power supply circuits 54 can be connected or disconnected.

[0099] In other embodiments, see Figure 7 The charging system 50 also includes multiple leakage current detection circuits 56 and multiple switching circuits 57. Each leakage current detection circuit 56 is connected in series with a switching circuit 57, and the DC bus 52 is connected to a power supply circuit 54 in the charging system 50 through this series connection of the leakage current detection circuit 56 and the switching circuit 57. In other words, the multiple leakage current detection circuits 56 and multiple switching circuits 57 are connected in series in a one-to-one correspondence, and each power supply circuit 54 in the charging system 50 is connected to the DC bus 52 through a corresponding set of series-connected leakage current detection circuits 56 and switching circuits 57.

[0100] Furthermore, any leakage current detection circuit 56 is used to detect the ground current in the circuit formed by the ground capacitance in a power supply circuit 54 connected to the DC bus 52. A switching circuit 57 connected in series with any leakage current detection circuit 56 is used to disconnect the circuit between the power supply circuit 54 and the DC bus 52 when the ground current detected by any leakage current detection circuit 56 is greater than a preset current.

[0101] For example, such as Figure 7 As shown, taking the charging system 50, which includes AC-DC conversion circuit 51a, AC-DC conversion circuit 51b, power supply circuit 54a, and power supply circuit 54b, as an example, the charging system 50 also includes leakage current detection circuit 56a, leakage current detection circuit 56b, switching circuit 57a, and switching circuit 57b. The AC-DC conversion circuit 51a and AC-DC conversion circuit 51b are connected in parallel to the DC bus 52. The leakage current detection circuit 56a and switching circuit 57a are connected in series between the DC bus 52 and the power supply circuit 54a, and the leakage current detection circuit 56b and switching circuit 57b are connected in series between the DC bus 52 and the power supply circuit 54b.

[0102] The leakage current detection circuit 56a is used to detect leakage current generated in the grounding circuit formed by the ground capacitance of either AC-DC conversion circuit 51a or AC-DC conversion circuit 51b and the power supply circuit 54a. The switching circuit 57a is used to disconnect the circuit between the DC bus 52 and the power supply circuit 54a when the leakage current detected by the leakage current detection circuit 56a is greater than a preset current. Similarly, the leakage current detection circuit 56b is used to detect leakage current generated in the grounding circuit formed by the ground capacitance of either AC-DC conversion circuit 51a or AC-DC conversion circuit 51b and the power supply circuit 54b. The switching circuit 57b is used to disconnect the circuit between the DC bus 52 and the power supply circuit 54b when the leakage current detected by the leakage current detection circuit 56b is greater than a first preset leakage current. For a detailed description, please refer to [reference needed]. Figure 6 The relevant descriptions of the embodiments shown will not be repeated here.

[0103] Based on the above design, each power circuit 54 in the charging system 50 can be connected to the DC bus 52 through a set of series-connected leakage current detection circuits 56 and switching circuits 57. This allows for timely disconnection of the circuit between the DC bus 52 and any power circuit 54 when the leakage current in the grounding circuit formed by the AC-DC conversion circuit 51 and the grounding capacitor in any power circuit 54 is large. This achieves precise fault isolation, provides ground insulation protection for the DC bus 52, and improves the operational safety of the charging system 50.

[0104] In some embodiments, combined with Figure 6 and Figure 7 The preset current can be less than or equal to 6A.

[0105] Figure 8 and Figure 9 These are another example provided in the embodiments of this application. Figure 4 The schematic diagram of the charging system 50 shown is shown.

[0106] and Figure 6 and Figure 7 The charging system 50 shown includes a leakage current detection circuit 56, but unlike the previous one, in... Figure 8 and Figure 9 In the illustrated embodiment, the charging device 50 may include a ground insulation resistance detection circuit 58, but not a leakage current detection circuit 56.

[0107] Specifically, in some embodiments, see [reference] Figure 8The charging system 50 also includes a switching circuit 57 and a ground insulation resistance detection circuit 58. The DC bus 52 is connected to one end of the ground insulation resistance detection circuit 58 via the switching circuit 57, and the other end of the ground insulation resistance detection circuit 58 is connected to the ground capacitance of each of the multiple power supply circuits 54. That is, the DC bus 52 is connected to multiple power supply circuits 54 through a set of series-connected switching short circuits 57 and the ground insulation resistance detection circuit 58.

[0108] In addition, the ground insulation resistance detection circuit 58 is used to detect the ground insulation resistance of the circuit containing the multiple power supply circuits 54 before the AC-DC conversion circuit 51 and the multiple power supply circuits 54 are started. The switching circuit 57 is used to connect the DC bus 52 and the ground capacitor in the multiple power supply circuits 54 before the AC-DC conversion circuit 51 and the multiple power supply circuits 54 are started, when the ground insulation resistance detected by the ground insulation resistance detection circuit 58 is greater than a preset insulation resistance.

[0109] For example, such as Figure 8 As shown, taking the charging system 50, which includes AC-DC conversion circuit 51a, AC-DC conversion circuit 51b, power supply circuit 54a, and power supply circuit 54b, as an example, AC-DC conversion circuit 51a and AC-DC conversion circuit 51b are connected in parallel to the DC bus 52. The DC bus 52 is connected to the power supply circuit 54a and power supply circuit 54b through a series-connected switch circuit 57 and a ground insulation resistance detection circuit 58. Taking the example that all AC-DC conversion circuits 51a, AC-DC conversion circuit 51b, power supply circuit 54a, and power supply circuit 54b need to be started, before starting AC-DC conversion circuits 51a, AC-DC conversion circuit 51b, power supply circuit 54a, and power supply circuit 54b, the charging system 50 can first disconnect the circuit between the DC bus 52 and the power supply circuits 54a and 54b by the switch circuit 57, and then detect the ground insulation resistance of the circuits containing the power supply circuits 54a and 54b through the ground insulation resistance detection circuit 58.

[0110] Furthermore, when the ground insulation impedance detected by the ground insulation impedance detection circuit 58 is less than or equal to the preset insulation impedance, the charging system 50 can still keep the switching circuit 57 in a state of disconnecting the circuit between the DC bus 52 and the power supply circuits 54a and 54b. However, when the ground insulation impedance detected by the ground insulation impedance detection circuit 58 is greater than the preset insulation impedance, the charging system 50 can make the switching circuit 57 conduct the circuit between the DC bus 52 and the power supply circuits 54a and 54b. And after the switching circuit 57 conducts the circuit between the DC bus 52 and the power supply circuits 54a and 54b, the charging system 50 can control the AC-DC conversion circuits 51a and 51b, the power supply circuits 54a and 54b to start and begin transmitting electrical energy.

[0111] Based on the above design, the DC bus 52 can be connected to each power circuit 54 in the charging system 50 through a set of series-connected ground insulation resistance detection circuits 58 and switching circuits 57. Before the AC-DC conversion circuit 51 and the multiple power circuits 54 are started, the charging system 50 can first disconnect the circuit between the DC bus 52 and the multiple power circuits 54 through the switching circuit 57. Then, when the ground insulation resistance of the circuit containing the multiple power circuits 54 is high, the circuit between the DC bus 52 and the multiple power circuits 54 can be reconnected through the switching circuit 57. This prevents safety issues caused by forcibly connecting the multiple power circuits 54 to the DC bus 52 when the ground insulation resistance of the circuit containing the multiple power circuits 54 is abnormal. Furthermore, ground insulation protection of the DC bus 52 can be achieved, improving the operational safety of the charging system 50.

[0112] In other embodiments, see Figure 9 The charging system 50 also includes multiple switching circuits 57 and multiple ground insulation resistance detection circuits 58. The DC bus 52 is connected to one end of a ground insulation resistance detection circuit 58 via one end of a switching circuit 57, and the other end of the ground insulation resistance detection circuit 58 is connected to the ground capacitor of a power supply circuit 54. In other words, the multiple ground insulation resistance detection circuits 58 and multiple switching circuits 57 are connected in series in a one-to-one correspondence, and each power supply circuit 54 in the charging system 50 is connected to the DC bus 52 via a set of series-connected ground insulation resistance detection circuits 58 and switching circuits 57.

[0113] Furthermore, any ground insulation resistance detection circuit 58 is used to detect the ground insulation resistance of the circuit containing the power supply circuit 54 before the AC-DC conversion circuit 51 and its connected power supply circuit 54 are started. A switching circuit 57 connected in series with the ground insulation resistance detection circuit 58 is used to connect the circuit between the connected power supply circuit 54 and the DC bus 52 before the AC-DC conversion circuit 51 and its connected power supply circuit 54 are started, provided that the ground insulation resistance detected by the ground insulation resistance detection circuit 58 is greater than a preset insulation resistance.

[0114] For example, such as Figure 9 As shown, taking the charging system 50, which includes AC-DC conversion circuit 51a, AC-DC conversion circuit 51b, power supply circuit 54a, and power supply circuit 54b, as an example, the charging system 50 also includes a ground insulation resistance detection circuit 58a, a ground insulation resistance detection circuit 58b, a switching circuit 57a, and a switching circuit 57b. The AC-DC conversion circuit 51a and AC-DC conversion circuit 51b are connected in parallel to the DC bus 52. The switching circuit 57a and the ground insulation resistance detection circuit 58a are connected in series between the DC bus 52 and the power supply circuit 54a. The switching circuit 57b and the ground insulation resistance detection circuit 58b are connected in series between the DC bus 52 and the power supply circuit 54b.

[0115] Taking the AC-DC conversion circuit 51a, AC-DC conversion circuit 51b and power supply circuit 54a as an example, before the AC-DC conversion circuit 51a, AC-DC conversion circuit 51b and power supply circuit 54a are started, the charging system can first disconnect the circuit between the DC bus 52 and the power supply circuit 54a by the switching circuit 57a, and then detect the ground insulation impedance of the circuit where the power supply circuit 54a is located by the ground insulation impedance detection circuit 58a.

[0116] Furthermore, when the ground insulation impedance detected by the ground insulation impedance detection circuit 58a is less than or equal to the preset insulation impedance, the charging system 50 can still keep the switching circuit 57a in the state of disconnecting the circuit between the DC bus 52 and the power supply circuit 54a. However, when the ground insulation impedance detected by the ground insulation impedance detection circuit 58a is greater than the preset insulation impedance, the charging system 50 can first turn on the circuit between the DC bus 52 and the power supply circuit 54a using the switching circuit 57a, and then control the AC-DC conversion circuit 51a, AC-DC conversion circuit 51b, and power supply circuit 54a to start and begin transmitting electrical energy. For a detailed description, please refer to [reference needed]. Figure 8 The relevant descriptions of the embodiments shown will not be repeated here.

[0117] Based on the above design, each power circuit 54 in the charging system 50 can be connected to the DC bus 52 through a set of series-connected switching circuits 57 and a ground insulation resistance detection circuit 58. Before the AC-DC conversion circuit 51 and any power circuit 54 are started, the charging system 50 can first disconnect the circuit between the DC bus 52 and any power circuit 54 through the switching circuit 57 connected to that power circuit 54. Then, when the ground insulation resistance of the circuit containing that power circuit 54 is high, the circuit between the DC bus 52 and that power circuit 54 is turned on. This prevents safety issues caused by forcibly connecting any power circuit 54 to the DC bus 52 when the ground insulation resistance of the circuit containing that power circuit is abnormal. Furthermore, precise fault isolation can be achieved to provide ground insulation protection for the DC bus 52, improving the operational safety of the charging system 50.

[0118] In some embodiments, combined with Figure 8 and Figure 9 The preset insulation resistance can be less than or equal to m×V bus / 30mA. Where 0.8≤m≤1.0, V bus This is the rated operating voltage of the DC bus. m can be, for example, 0.8, 0.84, 0.86, 0.9, 0.94, 0.96, or 1.0, etc. V bus For example, it can be 820V, 1000V or 1500V, etc.

[0119] In some embodiments, combined with Figures 6 to 9 The charging system 50 also includes a fuse group 59. The DC bus 52 is connected to the ground capacitance of each of the multiple power circuits 54 via the fuse group 59. The fuse group 59 is used to disconnect the circuit between the DC bus 52 and the multiple power circuits 54 when the Joule heat generated by the current flowing through it exceeds a preset threshold. The Joule heat generated by the fuse 59 is I... 2 T, I is the current flowing through fuse 59, and T is the time the current flows.

[0120] It should be understood that, in the embodiments of this application, the current flowing through the fuse group 59 can refer to the current output from the DC bus 52 to the multiple power supply circuits 54, or it can refer to the current output from the multiple power supply circuits 54 to the DC bus 52.

[0121] Specifically, such as Figures 6 to 9 As shown, taking the charging system 50, which includes power supply circuit 54a and power supply circuit 54b, as an example, the fuse group 59 includes fuse F1 and fuse F2. The positive DC bus Bus+ and the negative DC bus Bus- in the DC bus 52 are connected to the power supply circuit 54a and the ground capacitor in the power supply circuit 54b respectively through fuse F1 and fuse F2.

[0122] Taking the example where both power supply circuits 54a and 54b are working, if the Joule heat generated by the current flowing through fuses F1 and F2 exceeds a preset threshold due to a fault in AC-DC conversion circuit 51 or a fault in power supply circuits 54a and 54b, fuses F1 and F2 can disconnect the circuit between DC bus 52 and power supply circuits 54a and 54b by melting, so as to prevent the circuit fault from spreading, thereby further improving the operational stability of charging system 50.

[0123] In some embodiments, the preset threshold is less than or equal to the pre-arc Joule set by fuses F1 and F2.

[0124] The charging system 50 provided in the embodiments of this application has been described above. It should be understood that all other structures in the charging system 50 except for the plurality of power supply circuits 54 can be provided in the charging device provided in the embodiments of this application. The charging device provided in the embodiments of this application will be described below.

[0125] This application also provides a charging device, which includes a DC bus, an AC-DC conversion circuit, and a DC-DC conversion circuit. The AC-DC conversion circuit converts received AC power into DC power, which is then output to the DC-DC conversion circuit via the DC bus. The DC bus connects to the ground capacitor of each of the multiple power circuits and transmits the DC power output from the ground capacitor of each power circuit to the DC-DC conversion circuit. The DC-DC conversion circuit performs power conversion on the DC power obtained from the DC bus and outputs it. Furthermore, the charging device includes an inductor bank; the DC bus is connected to the AC-DC conversion circuit via the inductor bank, or the DC bus is connected to the ground capacitor of each power circuit via the inductor bank.

[0126] It should be understood that for detailed descriptions of the DC bus, AC-DC conversion circuit, DC-DC conversion circuit and inductor group in the charging equipment, please refer to the relevant descriptions of the DC bus 52, AC-DC conversion circuit 51, first DC-DC conversion circuit 53 and inductor group 55 in the charging system 50 mentioned above, which will not be repeated here.

[0127] Based on the above design, when multiple power supply circuits are connected to the DC bus, the inductor group can be connected in series in the grounding circuit formed by the DC bus and the ground capacitance of the multiple power supply circuits in the AC-DC conversion circuit. In this way, by increasing the inductive reactance of the inductor group, the total impedance in the grounding circuit can be increased. Since the leakage current generated in the grounding circuit is negatively correlated with the total impedance in the grounding circuit, the leakage current in the grounding circuit can be reduced. Furthermore, this prevents the filter in the AC-DC conversion circuit from easily saturating due to multiple power supply circuits connected to the DC bus, thereby ensuring the operational reliability of the charging equipment when multiple power supply circuits are connected to the DC bus.

[0128] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A charging system, characterized by, The charging system comprises a direct current bus, an alternating current-direct current AC-DC conversion circuit, a direct current-direct current DC-DC conversion circuit and a plurality of power supply circuits, the AC-DC conversion circuit is used for converting received alternating current into direct current and then outputting the direct current to the DC-DC conversion circuit through the direct current bus, each power supply circuit comprises a direct current power supply and a ground capacitor, the direct current power supply is connected to the direct current bus through the ground capacitor, the direct current power supply is used for outputting direct current to the DC-DC conversion circuit through the direct current bus, and the DC-DC conversion circuit is used for performing power conversion on the direct current obtained from the direct current bus and then outputting the direct current. The charging system further comprises an inductor group, the direct current bus is connected to the AC-DC conversion circuit through the inductor group, or the direct current bus is connected to the ground capacitor of each power supply circuit through the inductor group.

2. The charging system of claim 1, wherein, The number of the AC-DC conversion circuits is multiple, and the number of the inductor groups is one group. The plurality of AC-DC conversion circuits are connected in parallel to the direct current bus, and the direct current bus is connected to the ground capacitor of each power supply circuit through the inductor group.

3. The charging system of claim 1, wherein, The number of the AC-DC conversion circuits is multiple, and the number of the inductor groups is multiple groups. One AC-DC conversion circuit is connected to the direct current bus through one inductor group.

4. The charging system according to any one of claims 1 to 3, characterized in that, The charging system further comprises a leakage current detection circuit and a switch circuit connected in series, the direct current bus is connected to the ground capacitor of each power supply circuit through the series connection of the leakage current detection circuit and the switch circuit. The leakage current detection circuit is used for detecting the ground current of a circuit formed by the direct current bus and the ground capacitor in the plurality of power supply circuits. The switch circuit is used for disconnecting the circuit between the direct current bus and the ground capacitor in the plurality of power supply circuits when the ground current detected by the leakage current detection circuit is greater than a preset current.

5. The charging system according to any one of claims 1 to 3, characterized in that, The charging system further comprises a plurality of leakage current detection circuits and a plurality of switch circuits, one leakage current detection circuit and one switch circuit are connected in series, and the direct current bus is connected to the ground capacitor of one power supply circuit through the series connection of the one leakage current detection circuit and the one switch circuit. The one leakage current detection circuit is used for detecting the ground current of a circuit formed by the direct current bus and the ground capacitor in the one power supply circuit. The one switch circuit is used for disconnecting the circuit between the direct current bus and the ground capacitor in the one power supply circuit when the ground current detected by the one leakage current detection circuit is greater than a preset current.

6. The charging system of any one of claims 1 to 3, wherein, The charging system further comprises a ground insulation impedance detection circuit and a switch circuit, the direct current bus is connected to one end of the ground insulation impedance detection circuit through the switch circuit, and the other end of the ground insulation impedance detection circuit is connected to the ground capacitor of each power supply circuit. The ground insulation impedance detection circuit is used to detect the ground insulation impedance of the circuit where the plurality of power supply circuits are located before the AC-DC conversion circuit and the plurality of power supply circuits are started; The switch circuit is used to turn on the circuit between the DC bus and the ground capacitor in the plurality of power supply circuits when the ground insulation impedance detected by the ground insulation impedance detection circuit is greater than the preset insulation impedance before the AC-DC conversion circuit and the plurality of power supply circuits are started.

7. The charging system according to any one of claims 1 to 3, characterized by, The charging system further comprises a plurality of ground insulation impedance detection circuits and a plurality of switch circuits, and one end of one of the ground insulation impedance detection circuits is connected to the DC bus through one of the switch circuits, and the other end of the one ground insulation impedance detection circuit is connected to the ground capacitor in one of the power supply circuits. The one ground insulation impedance detection circuit is used to detect the ground insulation impedance of the circuit where the one power supply circuit is located before the AC-DC conversion circuit and the one power supply circuit are started. The one switch circuit is used to turn on the circuit between the DC bus and the ground capacitor in the one power supply circuit when the ground insulation impedance detected by the one ground insulation impedance detection circuit is greater than the preset insulation impedance before the AC-DC conversion circuit and the one power supply circuit are started.

8. A charging device, characterized by The charging device comprises a DC bus, an AC-DC conversion circuit, and a DC-DC conversion circuit, the AC-DC conversion circuit is used to convert received alternating current into direct current and output the direct current to the DC-DC conversion circuit through the DC bus, the DC bus is used to connect the ground capacitor of each power supply circuit in a plurality of power supply circuits, the DC bus is used to deliver the direct current output from the ground capacitor of each power supply circuit to the DC-DC conversion circuit, and the DC-DC conversion circuit is used to perform power conversion on the direct current obtained from the DC bus and output the direct current. The charging device further comprises an inductor group, the DC bus is connected to the AC-DC conversion circuit through the inductor group, or the DC bus is used to connect the ground capacitor of each power supply circuit through the inductor group.

9. The charging apparatus according to claim 8, characterized by, The number of AC-DC conversion circuits is multiple, and the number of inductor groups is one group; wherein, A plurality of AC-DC conversion circuits are connected in parallel to the DC bus, and the DC bus is used to connect the ground capacitor of each power supply circuit through a group of inductors.

10. The charging apparatus according to claim 8, characterized by, The number of AC-DC conversion circuits is multiple, and the number of inductor groups is multiple; wherein, One of the AC-DC conversion circuits is connected to the DC bus through a group of inductors.

11. The charging device according to any one of claims 8 to 10, characterized in that, The charging device further comprises a series of leakage current detection circuits and switch circuits, and the DC bus is used to connect the ground capacitor of each power supply circuit through the series of leakage current detection circuits and switch circuits; The leakage current detection circuit is used to detect the ground current of the circuit formed by the DC bus and the ground capacitor in the plurality of power supply circuits; The switch circuit is used to disconnect the circuit between the DC bus and the ground capacitance in the plurality of power supply circuits when the ground current detected by the leakage current detection circuit is greater than a preset current.

12. The charging device according to any one of claims 8 to 10, characterized in that, The charging device further comprises a plurality of leakage current detection circuits and a plurality of switch circuits, one leakage current detection circuit and one switch circuit are connected in series, and the DC bus is used to connect the ground capacitance of one power supply circuit through the series connection of the one leakage current detection circuit and the one switch circuit. The one leakage current detection circuit is used to detect the ground current of the circuit formed by the DC bus and the ground capacitance in the one power supply circuit. The one switch circuit is used to disconnect the circuit between the DC bus and the ground capacitance in the one power supply circuit when the ground current detected by the one leakage current detection circuit is greater than a preset current.

13. The charging apparatus according to any one of claims 8 to 10, characterized by, The charging device further comprises a ground insulation impedance detection circuit and a switch circuit, the DC bus is connected to one end of the ground insulation impedance detection circuit through the switch circuit, and the other end of the ground insulation impedance detection circuit is connected to the ground capacitance of each power supply circuit. The ground insulation impedance detection circuit is used to detect the ground insulation impedance of the circuit in which the plurality of power supply circuits are located before the AC-DC conversion circuit and the plurality of power supply circuits are started. The switch circuit is used to turn on the circuit between the DC bus and the ground capacitance in the plurality of power supply circuits when the ground insulation impedance detected by the ground insulation impedance detection circuit is greater than a preset insulation impedance before the AC-DC conversion circuit and the plurality of power supply circuits are started.

14. The charging apparatus according to any one of claims 8 to 10, characterized by, The charging device further comprises a plurality of ground insulation impedance detection circuits and a plurality of switch circuits, the DC bus is connected to one end of one ground insulation impedance detection circuit through one switch circuit, and the other end of the one ground insulation impedance detection circuit is connected to the ground capacitance in one power supply circuit. The one ground insulation impedance detection circuit is used to detect the ground insulation impedance of the circuit in which the one power supply circuit is located before the AC-DC conversion circuit and the one power supply circuit are started. The one switch circuit is used to turn on the circuit between the DC bus and the ground capacitance in the one power supply circuit when the ground insulation impedance detected by the one ground insulation impedance detection circuit is greater than a preset insulation impedance before the AC-DC conversion circuit and the one power supply circuit are started.

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