Alternating current to direct current device and charging pile

Abstract

The embodiment of the invention provides an AC-DC conversion device and a charging pile. The AC-DC conversion device comprises an input capacitance circuit, an AC-DC conversion circuit, one or more first switches connected in parallel and a first slow start circuit. Each input end except one input end in a plurality of input ends of the input capacitor circuit is used for being connected with an alternating current power supply through a first switch, and each first slow start circuit comprises a second switch and a current limiting resistor which are connected in series. The AC-DC conversion device is used for switching off the first switch and the second switch in the first slow start circuit when the AC-DC conversion circuit is in a standby state; before the AC-DC conversion circuit is started, the second switch in the first slow start circuit is closed firstly, and then the first switch connected with the first slow start circuit in parallel is closed. Furthermore, not only can the reactive power loss of the AC-DC conversion device in a standby state be reduced, but also the AC-DC conversion device can be prevented from being impacted by a relatively large current when being started.

Description

Technical Field

[0001] The present application relates to the field of charging, and more specifically, to an AC to DC conversion device and a charging pile. Background Art

[0002] With the rapid popularization of electric vehicles, the application of charging piles as supporting facilities is becoming more and more extensive. As the core unit of the charging pile, the alternating current-direct current (AC-DC) conversion device mainly includes a switch, an input capacitor and an AC-DC conversion circuit. Among them, the input end of the AC-DC conversion circuit is connected to the power grid through the input capacitor and the switch, and the AC-DC conversion circuit is used to convert the alternating current output from the power grid into direct current.

[0003] At present, in order to alleviate the large current impact on the switch when the AC-DC conversion circuit is powered on, the input end of the AC-DC conversion circuit is connected to the input capacitor through a switch, and then connected to the power grid through the input capacitor. However, in the above design, when the AC-DC conversion device is in standby mode, the input capacitor is still connected to the power grid after the switch is disconnected, resulting in a large reactive power loss of the AC-DC conversion device when in standby mode. Summary of the invention

[0004] The present application provides an AC-DC conversion device and a charging pile, which can not only reduce the reactive power loss of the AC-DC conversion device when in standby mode, but also prevent the AC-DC conversion device from being subjected to a large current shock when starting, thereby improving the circuit operation stability of the charging pile.

[0005] In a first aspect, an AC-DC converter is provided, which includes an input capacitor circuit, an AC-DC converter circuit, one or more first switches, and one or more first slow-start circuits. The multiple input terminals of the input capacitor circuit are used to connect to an AC power source, and the AC-DC converter circuit is used to convert the AC power output from the input capacitor circuit into DC power and then output it. Among them, each of the multiple input terminals of the input capacitor circuit except one input terminal is used to connect to the AC power source through a first switch. Each first slow-start circuit includes a second switch and a current limiting resistor in series, and each first slow-start circuit is connected in parallel with a first switch. The AC-DC converter is used to: when the AC-DC converter circuit is on standby, disconnect one or more first switches and one or more second switches in the first slow-start circuit; before the AC-DC converter circuit is started, first close the second switches in one or more first slow-start circuits so that the AC power source pre-charges the input capacitor in the input capacitor circuit through the first slow-start circuit, and then close the first switch connected in parallel with the first slow-start circuit.

[0006] In the above technical solution, when the AC-DC conversion circuit is in standby mode, the circuit between the AC power supply and the input capacitor circuit can be disconnected by disconnecting the first switch and the second switch in the first slow-start circuit. This can prevent the input capacitor in the input capacitor circuit from being charged and discharged by the AC power supply when the AC-DC conversion circuit is in standby mode, thereby reducing the reactive power loss of the AC-DC conversion device when the AC-DC conversion circuit is in standby mode.

[0007] Furthermore, when the AC-DC conversion circuit needs to be started, the second switch can be closed first, so that the input capacitor circuit forms a loop with the AC power supply through the connected first slow-start circuit, and the AC power supply pre-charges the input capacitor. When the second switch is closed, the current limiting resistor is used to limit the current, which can prevent the second switch from generating a large impact current due to the large voltage difference between the two ends of the second switch connected to the input capacitor. As the pre-charging process proceeds, the voltage across the input capacitor increases, so that the difference between the voltage across the input capacitor and the output voltage of the AC power supply decreases. In this way, in the loop formed by the input capacitor circuit and the AC power supply, the current flowing through the first slow-start circuit decreases, and the voltage difference across the two ends of the first slow-start circuit decreases accordingly. Correspondingly, the voltage difference across the two ends of the first switch connected in parallel with the first slow-start circuit decreases. In this case, closing the first switch can alleviate the problem of generating a large impact current on the first switch due to the large voltage difference across the two ends of the first switch. After the first switch is closed, the AC power supply supplies power to the AC-DC conversion circuit through the first switch and the input capacitor circuit, so that the AC-DC conversion circuit starts to work. Furthermore, the AC-DC conversion circuit can be prevented from being subjected to a large current shock when starting, thereby improving the circuit operation stability of the AC-DC conversion device.

[0008] In addition, since the embodiment of the present application can alleviate the problem of generating a large impact current when the first switch and the second switch are closed, the first switch and the second switch can use relays with a lower impact current tolerance than the contactor. Compared with the contactor, the cost of the relay is lower, which is more conducive to the cost optimization of the AC-DC conversion device.

[0009] In one embodiment, the AC-DC converter further includes a third switch, and an input end of the input capacitor circuit is used to connect to an AC power source through the third switch. The AC-DC converter is used to close the third switch before starting the AC-DC converter circuit, and then close the second switch in one or more first slow-start circuits.

[0010] In the above technical solution, one of the multiple input terminals of the input capacitor circuit that is not connected to the first switch can be connected to the AC power supply through the third switch, so that each input terminal of the input capacitor circuit is connected to the AC power supply through the switch. In this way, by controlling the on-off state of the switch connected to each input terminal, the input capacitor circuit can be completely disconnected from the AC power supply in some abnormal situations, thereby further improving the circuit operation safety of the AC-DC conversion device.

[0011] In addition, when the third switch is closed and the first switch and the second switch are both opened, only one of the multiple input ends of the input capacitor circuit connected to the third switch is connected to the circuit between the AC power supply, while the circuits between the other input ends and the AC power supply are disconnected. In other words, the loop between the input capacitor circuit and the AC power supply is disconnected, and no inrush current is generated between the AC power supply and the input capacitor circuit. Therefore, in the embodiment of the present application, before the AC-DC conversion circuit is started, the third switch is closed first and then the second switch is closed, which can ensure that no inrush current is generated between the AC power supply and the input capacitor circuit at the moment the third switch is closed, thereby improving the circuit operation stability of the AC-DC conversion device.

[0012] In one embodiment, the charging pile is also used to: before the AC-DC conversion circuit is started, after the first switch is closed, disconnect the second switch in the first slow-start circuit connected in parallel with the first switch; after the second switch of one or more first slow-start circuits is disconnected, control the start of the AC-DC conversion circuit.

[0013] In the above technical solution, the AC-DC conversion circuit is controlled to start after the second switches connected to the input capacitor circuit are disconnected, which can reduce the power consumption when the AC power output by the AC power supply flows to the AC-DC conversion circuit through the current limiting resistor in the first slow-start circuit when the AC-DC conversion circuit is working, thereby improving the power utilization rate of the AC-DC conversion device.

[0014] In one embodiment, the charging pile is used to reclose the first switch connected in parallel with the first slow-start circuit, including: when the voltage across the input capacitor connected to the second switch in the first slow-start circuit is greater than or equal to the first preset voltage, reclosing the first switch connected in parallel with the first slow-start circuit.

[0015] In the above technical solution, before the AC-DC conversion circuit is started, the input capacitor is pre-charged by the first slow-start circuit until the voltage across the input capacitor is greater than or equal to the first preset voltage. When the voltage across the input capacitor is greater than or equal to the first preset voltage, the voltage difference across the first switch connected to the input capacitor is small, so no large inrush current is generated when the first switch is closed. In addition, the circuit operation stability of the AC-DC conversion device can be improved.

[0016] In one embodiment, the AC-DC conversion circuit includes a bus capacitor circuit, and the AC-DC conversion circuit is used to output the converted direct current through the bus capacitor circuit. Wherein, the bus capacitor circuit includes a bus capacitor, and the rated capacity of the bus capacitor is greater than the sum of the rated capacities of the input capacitors in the input capacitor circuit, or the bus capacitor circuit includes multiple bus capacitors connected in series, and the equivalent rated capacity of the multiple bus capacitors is greater than the sum of the rated capacities of the input capacitors in the input capacitor circuit. The AC-DC conversion device is used to reclose the first switch connected in parallel with the first slow-start circuit, including: when the voltage across the bus capacitor circuit is greater than or equal to the second preset voltage, reclosing the first switch connected in parallel with one or more first slow-start circuits.

[0017] In the above technical solution, after the second switch is closed, the AC power supply can also pre-charge the bus capacitor in the AC-DC conversion circuit through the first slow-start circuit and the diode in the AC-DC conversion circuit. It should be understood that when the AC-DC conversion circuit does not receive AC power, the bus capacitor of the AC-DC conversion circuit may discharge, resulting in a low voltage at both ends of the bus capacitor circuit. When the AC-DC conversion circuit receives AC power, the rectifier bridge arm in the AC-DC conversion circuit converts the AC power output by the AC power supply into DC power and applies it to both ends of the bus capacitor circuit. Since the DC voltage applied by the rectifier bridge arm may differ greatly from the voltage at both ends of the bus capacitor circuit when the AC power is not received, it is easy to cause the AC-DC conversion circuit to generate a large impact current when starting and powering on. In an embodiment of the present application, before the AC-DC conversion circuit starts and powers on, the AC power supply is first pre-charged to the bus capacitor through the first slow-start circuit, which can increase the voltage at both ends of the bus capacitor circuit. Furthermore, when the AC-DC conversion circuit is started and powered on, the difference between the DC voltage applied by the rectifier bridge arm and the voltage across the bus capacitor circuit can be reduced, thereby preventing a large impact current from being generated in the AC-DC conversion circuit due to the low voltage across the bus capacitor circuit.

[0018] In addition, since the total rated capacity of the bus capacitors in the bus capacitor circuit is greater than the sum of the rated capacities of the input capacitors in the input capacitor circuit, when the voltage across the bus capacitor circuit is precharged to a preset voltage that meets the requirements, the voltage across each input capacitor in the input capacitor circuit has also been precharged to a preset voltage that meets the requirements. For example, when the voltage across the bus capacitor circuit is precharged to a second preset voltage, the voltage across each input capacitor has also been precharged to a voltage greater than or equal to the first preset voltage. At this time, the voltage difference across the first switch connected to the input capacitor is small, and closing the first switch will not generate a large inrush current. Moreover, the voltage difference between the voltage across the bus capacitor circuit and the DC voltage applied by the rectifier bridge arm is also small, and starting the AC-DC conversion circuit will not generate a large inrush current. In addition, the circuit operation stability of the AC-DC conversion device is improved.

[0019] In one embodiment, the AC-DC conversion circuit includes a bus capacitor circuit, the bus capacitor circuit includes a bus capacitor or multiple bus capacitors connected in series, and the AC-DC conversion circuit is used to output the converted direct current through the bus capacitor circuit. The charging pile also includes a second slow-start circuit, the second slow-start circuit is connected to the bus capacitor circuit, and the second slow-start circuit is used to pre-charge the bus capacitor in the bus capacitor circuit. Among them, the AC-DC conversion device is used to control the second slow-start circuit to pre-charge the bus capacitor in the bus capacitor circuit before the AC-DC conversion circuit is started, and then close the second switch in one or more first slow-start circuits.

[0020] In the above technical solution, before closing the second switch, each bus capacitor in the bus capacitor circuit can be pre-charged through the second slow-start circuit to increase the voltage at both ends of the bus capacitor circuit. It should be understood that when the total rated capacity of the bus capacitor in the bus capacitor circuit is large, in order to prevent the bus capacitor circuit from generating a large inrush current when the AC-DC conversion circuit is started and powered on, the AC power supply needs to work for a long time through the first slow-start circuit to pre-charge the bus capacitor, and the long working time is likely to cause a large energy loss in the first slow-start circuit. Therefore, in the embodiment of the present application, the bus capacitor is pre-charged through the second slow-start circuit first, which can increase the voltage at both ends of the bus capacitor circuit, and then the bus capacitor is continued to be charged through the first slow-start circuit to reduce the duration of the AC power supply charging the bus capacitor through the first slow-start circuit. Furthermore, the energy loss of the first slow-start circuit during operation can be reduced.

[0021] In one embodiment, the AC-DC conversion device is used to reclose the second switch in one or more first slow-start circuits, including: the AC-DC conversion device is used to reclose the second switch in one or more first slow-start circuits when the voltage across the bus capacitor circuit is greater than a third preset voltage.

[0022] In the above technical solution, when the voltage at both ends of the bus capacitor circuit is precharged to a voltage greater than the third preset voltage, the voltage difference between the voltage at both ends of the bus capacitor circuit and the voltage applied to the bus capacitor circuit by the rectifier bridge arm of the AC-DC conversion circuit is small, and even if the bus capacitor is not precharged through the first slow-start circuit, the bus capacitor circuit can be prevented from generating a large impact current when the AC-DC conversion circuit is powered on. Therefore, when the voltage at both ends of the bus capacitor circuit is precharged to a voltage greater than the third preset voltage, the second switch is closed, and the process of precharging the bus capacitor by the first slow-start circuit can be ignored. The first slow-start circuit can be used only to precharge the input capacitor, and when the voltage at both ends of the input capacitor is precharged to a voltage greater than or equal to the first preset voltage, the second switch is disconnected. In this way, the problem of large energy loss of the first slow-start circuit during operation due to the long duration of the AC power supply precharging the bus capacitor through the first slow-start circuit can be prevented.

[0023] In one embodiment, the AC-DC converter is used to control the second slow-start circuit to pre-charge the bus capacitor in the bus capacitor circuit before the AC-DC converter is started, then close the third switch, and then close the second switch in one or more first slow-start circuits. In this way, it can prevent the problem of large energy loss of the first slow-start circuit during operation due to the long duration of the AC power supply pre-charging the bus capacitor through the first slow-start circuit, and it can also ensure that no impact current is generated between the AC power supply and the input capacitor circuit at the moment when the third switch is closed, thereby improving the circuit operation stability of the AC-DC converter.

[0024] In a second aspect, a charging pile is provided, which includes an AC-DC converter and a charging gun. The AC-DC converter is used to convert the AC power output by the AC power supply into DC power and then output it to the charging gun. Among them, the AC-DC converter includes an input capacitor circuit, an AC-DC converter circuit, one or more first switches, and one or more first slow-start circuits. The multiple input ends of the input capacitor circuit are used to connect the AC power supply, and the AC-DC converter circuit is used to convert the AC power output from the input capacitor circuit into DC power and then output it to the charging gun. Among them, each of the multiple input ends of the input capacitor circuit except one input end is used to connect the AC power supply through a first switch. Each first slow-start circuit includes a second switch and a current limiting resistor in series, and each first slow-start circuit is connected in parallel with a first switch. The AC-DC converter is used to: when the AC-DC converter circuit is on standby, disconnect one or more first switches and one or more second switches in the first slow-start circuit; before the AC-DC converter circuit is started, first close the second switch in one or more first slow-start circuits, so that the AC power supply pre-charges the input capacitor in the input capacitor circuit through the first slow-start circuit, and then closes the first switch connected in parallel with the first slow-start circuit.

[0025] In one embodiment, the AC-DC conversion device further includes a third switch, and an input end of the input capacitor circuit is used to connect the AC power supply through the third switch. The AC-DC conversion device is used to close the third switch first and then close the second switch in one or more first slow-start circuits before starting the AC-DC conversion circuit.

[0026] In one embodiment, the AC-DC conversion device is also used to: before the AC-DC conversion circuit is started, after closing the first switch, disconnect the second switch in the first slow-start circuit connected in parallel with the first switch; after the second switch in one or more first slow-start circuits is disconnected, control the start of the AC-DC conversion circuit.

[0027] In one embodiment, the AC-DC conversion device is used to reclose the first switch connected in parallel with the first slow-start circuit, including: the AC-DC conversion device is used to reclose the first switch connected in parallel with the first slow-start circuit when the voltage across the input capacitor connected to the second switch in the first slow-start circuit is greater than or equal to a first preset voltage.

[0028] In one embodiment, the AC-DC conversion circuit includes a bus capacitor circuit, and the AC-DC conversion circuit is used to output the converted direct current to the charging gun through the bus capacitor circuit. Wherein, the bus capacitor circuit includes a bus capacitor, and the rated capacity of the bus capacitor is greater than the sum of the rated capacities of the input capacitors in the input capacitor circuit, or the bus capacitor circuit includes multiple bus capacitors connected in series, and the equivalent rated capacity of the multiple bus capacitors is greater than the sum of the rated capacities of the input capacitors in the input capacitor circuit. The AC-DC conversion device is used to reclose the first switch connected in parallel with the first slow-start circuit, including: the AC-DC conversion device is used to reclose the first switch connected in parallel with one or more first slow-start circuits when the voltage across the bus capacitor circuit is greater than or equal to the second preset voltage.

[0029] In one embodiment, the AC-DC conversion circuit includes a bus capacitor circuit, and the AC-DC conversion circuit is used to output the converted direct current to the charging gun through the bus capacitor circuit. The AC-DC conversion device also includes a second slow-start circuit, the second slow-start circuit is connected to the bus capacitor circuit, and the second slow-start circuit is used to pre-charge the bus capacitor in the bus capacitor circuit. The charging pile is used to control the second slow-start circuit to pre-charge the bus capacitor in the bus capacitor circuit before starting the AC-DC conversion circuit, and then close the second switch in one or more first slow-start circuits.

[0030] In the above technical solution, the second slow-start circuit provided in the AC-DC converter is connected to the bus capacitor circuit, so when there are multiple AC-DC converters in the charging pile, each AC-DC converter can pre-charge its own bus capacitor through its own second slow-start circuit, that is, the pre-charging process of the bus capacitor of each AC-DC converter is independently operated. Thus, the circuit operation reliability of multiple AC-DC converters can be improved.

[0031] In one embodiment, the charging pile also includes a DC bus, and the number of AC-DC conversion devices is multiple, and the multiple AC-DC conversion devices are connected in parallel to the DC bus. The AC-DC conversion circuit includes a bus capacitor circuit, and the AC-DC conversion circuit is used to output the converted DC power to the DC bus through the bus capacitor circuit, and the DC bus is connected to the charging gun. The charging pile also includes a second slow-start circuit, and the second slow-start circuit is connected to the DC bus. The second slow-start circuit is used to pre-charge the bus capacitor in the bus capacitor circuit through the DC bus. The charging pile is used to control the second slow-start circuit to pre-charge the bus capacitor in the bus capacitor circuit before starting the AC-DC conversion circuit, and then close the second switch in one or more first slow-start circuits.

[0032] In the above technical solution, by connecting the second slow-start circuit to the DC bus, the second slow-start circuit can pre-charge the bus capacitor of each AC-DC converter in the charging pile through the DC bus. This can reduce the number of slow-start circuits in the charging pile that pre-charge the bus capacitors of multiple AC-DC converters, thereby reducing the complexity of the circuit design in the charging pile, which is beneficial to the cost optimization of the charging pile.

[0033] In one embodiment, the charging pile is used to reclose the second switch in one or more first slow-start circuits, including: the charging pile is used to reclose the second switch in one or more first slow-start circuits when the voltage across the bus capacitor circuit is greater than a third preset voltage.

[0034] In one embodiment, the charging pile is used to control the second slow-start circuit to pre-charge the bus capacitor in the bus capacitor circuit before starting the AC-DC conversion circuit, then close the third switch, and then close the second switch in one or more first slow-start circuits.

[0035] In one embodiment, the charging pile further includes a plurality of DC-DC conversion devices, the plurality of DC-DC conversion devices are connected in parallel to a DC bus, and the DC bus is connected to a charging gun through the plurality of DC-DC conversion devices. The charging pile is used to control the plurality of DC-DC conversion devices to start after the AC-DC conversion circuits in the plurality of AC-DC conversion devices are started.

[0036] In the above technical solution, by starting the AC-DC conversion circuits of multiple AC-DC conversion devices in the charging pile and then starting the DC-DC conversion device, it is possible to prevent the safety problem caused by the impact current generated when the AC-DC conversion circuit is started again after the DC-DC conversion device is started and flowing through the started DC-DC conversion device.

[0037] For the beneficial effects of the second aspect that are not detailed, please refer to the beneficial effects of the first aspect mentioned above, which will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 It is a schematic diagram of a charging system provided in an embodiment of the present application.

[0039] Figure 2 This is an example provided in the embodiment of the present application. Figure 1 The specific structural diagram of the charging pile is shown.

[0040] Figure 3 It is a structural schematic diagram of an AC-DC conversion device provided in an embodiment of the present application.

[0041] Figures 4 to 8 An example provided in the embodiment of the present application is Figure 3 The specific structural diagram of the AC-DC conversion device shown.

[0042] Fig. 9 It is a structural schematic diagram of a charging pile provided in an embodiment of the present application.

[0043] Fig.10 and Fig.11 An example provided in the embodiment of the present application is Fig. 9 The specific structural diagram of the charging pile is shown. DETAILED DESCRIPTION

[0044] To facilitate understanding of the embodiments of the present application, the following points are explained before introducing the embodiments of the present application.

[0045] In the description of the embodiments of the present application, connection may refer to electrical connection. Electrical connection may be understood as the transmission of signals between two electrical components by direct electrical connection or indirect electrical connection. For example, A and B are electrically connected, which may be understood as A and B are directly electrically connected, or may be understood as A and B are indirectly electrically connected through one or more other electrical components.

[0046] In the embodiments of the present application, the terms "first" and "second" are used only for descriptive purposes and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may include one or more features either sensibly or implicitly. In addition, in the description of the embodiments of the present application, "multiple" refers to two or more than two, and "at least one" and "one or more" refer to one, two or more than two.

[0047] In the description of the embodiments of the present application, unless otherwise specified, "and / or" is merely a description of the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can represent three situations: A exists alone, A and B exist at the same time, and B exists alone.

[0048] The technical solution in this application will be described below in conjunction with the accompanying drawings.

[0049] First, to facilitate understanding of the technical solutions provided by the embodiments of the present application, application scenarios applicable to the embodiments of the present application are first introduced.

[0050] Figure 1 It is a structural schematic diagram of a charging system 10 provided in an embodiment of the present application.

[0051] Combination Figure 1 In (a) and (b), the charging system 10 includes a charging pile 11 and an electric vehicle 12. The charging pile 11 is used to receive the alternating current output by the power grid 20, and convert the alternating current into stable direct current and then transmit it to the electric vehicle 12 to charge the electric vehicle 12. Alternatively, in some other embodiments, the electric vehicle 12 can also output electric energy to the power grid 20 through the charging pile 11.

[0052] In some embodiments, Figure 1 As shown in (a) of FIG. 1 , the charging pile 11 is a split type charging pile. Specifically, the charging pile 11 includes a charging host 111 , one or more charging terminals 112 , and one or more charging guns 113 .

[0053] The charging host 111 includes a plurality of charging modules (not shown in the figure), and the output ends of the plurality of charging modules are connected to each charging terminal 112. The plurality of charging modules are used to convert the alternating current output by the power grid 20 into stable direct current and then transmit it to the charging terminal 112. The plurality of charging modules include, for example, an AC-DC converter and a DC-DC converter. The specific description of the AC-DC converter and the DC-DC converter will be introduced below and will not be repeated here.

[0054] Each charging terminal 112 is connected to at least one of the one or more charging guns 113, and each charging gun 113 is used to connect to the electric vehicle 12. One electric vehicle 12 can be connected to one charging gun 113 or multiple charging guns 113. In a specific implementation, the charging terminal 112 is used to transmit the direct current output by multiple charging modules to the electric vehicle 12 through the connected charging guns 113.

[0055] It should be understood that in the embodiment of the present application, the charging terminal 112 includes a housing, a human-computer interaction interface, a charging control unit, and a metering and billing unit, etc., to perform information interaction, energy transmission, metering and billing, etc. with the electric vehicle 12.

[0056] It should also be understood that in the embodiment of the present application, the electric vehicle 12 is a vehicle driven by electric energy. The electric vehicle 12 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).

[0057] In some other embodiments, as shown in (b) of FIG. (1), the charging pile 11 is an integrated charging pile. Specifically, the human-machine interface, charging control unit, metering and billing unit, etc. in the charging pile 11 are directly arranged in the charging host 111, so that the charging pile 11 may include the charging host 111 and the charging gun 113 connected to the charging host 111, but does not include the charging terminal 112. In a specific implementation, the multiple charging modules in the charging host 111 convert the AC power output by the power grid 20 into stable DC power, and then directly transmit it to the electric vehicle 12 through the charging gun 113.

[0058] Below Figure 1 Taking the split charging pile shown in (a) as an example, the structure of the charging host 111 in the charging pile 11 is further introduced.

[0059] Figure 2 This is an example provided in the embodiment of the present application. Figure 1 Schematic diagram of the specific structure of the charging pile 11 shown in (a).

[0060] See also Figure 2The charging host 111 includes one or more AC-DC conversion devices 1111, one or more DC-DC conversion devices 1112, a DC bus 1113 and a power distribution device 1114. Figure 2 The example shows that the charging host 111 includes multiple AC-DC conversion devices 1111 and multiple DC-DC conversion devices 1112. The input end of each AC-DC conversion device 1111 is connected to the power grid 20, and the output end of each AC-DC conversion device 1111 is connected to the input end of each DC-DC conversion device 1112 through a DC bus 1113. The output end of each DC-DC conversion device 1112 is connected to each charging terminal 112 in the charging pile 11 through a power distribution device 1114, and each charging terminal 112 is connected to a charging gun 113.

[0061] In a specific implementation, each AC-DC converter 1111 is used to convert the alternating current output from the power grid 20 into direct current and output it to the direct current bus 1113. Each DC-DC converter 1112 is used to further convert the direct current obtained from the direct current bus 1113 into direct current suitable for the electric vehicle 12 and output it to the power distribution device 1114. The power distribution device 1114 is used to dynamically distribute the direct current output from each DC-DC converter 1112 according to the actual charging power required by the electric vehicle 12, and transmit the distributed power to the charging gun 113 through the charging terminal 112, so that the power output by the charging gun 113 to the electric vehicle 12 meets the charging demand of the electric vehicle 12.

[0062] As described in the above background technology section, the AC-DC converter 1111 generally includes an AC-DC converter circuit, a switch, and an input capacitor. Since when the AC-DC converter circuit is powered on, the input capacitor is directly connected to the power grid 20, which is prone to generate a large impact current. Therefore, in order to avoid the switch from being impacted by a large current, the input end of the AC-DC converter circuit is currently mostly connected to the input capacitor through a switch, and then connected to the power grid 20 through the input capacitor. However, in the above design, when the AC-DC converter 1111 is in standby mode, the input capacitor is still connected to the power grid 20 after the switch is disconnected, resulting in a large reactive power loss of the AC-DC converter 1111 when in standby mode.

[0063] Based on the above content, the embodiment of the present application provides an AC-DC conversion device and a charging pile, which can not only reduce the reactive loss of the AC-DC conversion device in standby mode, but also prevent the AC-DC conversion device from being subjected to a large current shock at startup, thereby improving the circuit operation stability of the charging pile.

[0064] The AC-DC conversion device provided in the embodiment of the present application is first introduced below with reference to the accompanying drawings.

[0065] Figure 3 is a schematic diagram of the structure of an AC-DC converter 30 provided in an embodiment of the present application. It should be understood that the AC-DC converter 30 may be Figure 2 The AC-DC conversion device 1111 is shown.

[0066] See also Figure 3 The AC-DC conversion device 30 includes an input capacitor circuit 31 and an AC-DC conversion circuit 32. The multiple input terminals of the input capacitor circuit 31 are used to connect to an AC power source, and the output terminal of the input capacitor circuit 31 is connected to the AC-DC conversion circuit 32 to transmit the AC power output by the AC power source to the AC-DC conversion circuit 32. The AC-DC conversion circuit 32 is used to convert the AC power output from the input capacitor circuit 31 into DC power and then output it.

[0067] It should be understood that in the embodiment of the present application, the AC-DC conversion circuit 32 can be an isolated AC-DC conversion circuit, or it can also be a non-isolated AC-DC conversion circuit. In addition, the AC-DC conversion circuit 32 can be a single-phase AC-DC conversion circuit, or it can also be a three-phase AC-DC conversion circuit, and the three-phase AC-DC conversion circuit can adopt three-phase three-wire or three-phase four-wire. When the AC-DC conversion circuit 32 is a single-phase AC-DC conversion circuit, the multiple input ends of the input capacitor circuit 31 connected to the AC-DC conversion circuit 32 include the live input end and the neutral input end. Alternatively, when the AC-DC conversion circuit 32 is a three-phase AC-DC conversion circuit, the multiple input ends of the input capacitor circuit 31 connected to the AC-DC conversion circuit 32 include the A-phase input end, the B-phase input end and the C-phase input end, and further include the neutral end.

[0068] It should also be understood that in the embodiment of the present application, the input capacitor circuit 31 includes one or more input capacitors. Each input capacitor can also be called an X capacitor. Each input capacitor is used to filter out clutter between the AC power supply and the AC-DC conversion circuit 32 to ensure that the electrical performance indicators of the AC-DC conversion circuit 32 are normal and the electromagnetic compatibility (EMC) meets the standard requirements.

[0069] The specific configuration of one or more input capacitors in the input capacitor circuit 31 will be introduced below and will not be repeated here.

[0070] Continue reading Figure 3The AC-DC converter 30 further includes one or more first switches K1 and one or more first slow-start circuits 33. Among the multiple input terminals of the input capacitor circuit 31, each other input terminal except one input terminal is used to connect to the AC power supply through a first switch K1. That is, among the multiple input terminals of the input capacitor circuit 31, one input terminal is used to directly connect to the AC power supply without passing through the first switch K1, and each of the remaining input terminals is used to connect to the AC power supply through a first switch K1.

[0071] In addition, each first slow-start circuit 33 includes a second switch K2 and a current-limiting resistor R connected in series, and each first slow-start circuit 33 is connected in parallel with a first switch K1. That is, one or more first slow-start circuits 33 in the AC-DC converter 30 are connected in parallel with one or more first switches K1 in a one-to-one correspondence. Exemplarily, the current-limiting resistor R can be a resistor or a negative temperature coefficient (NTC) thermistor.

[0072] In the above technical solution, each of the multiple input terminals of the input capacitor circuit 31 except one input terminal is connected to the AC power supply through a first switch K1 and a first slow-start circuit 33 connected in parallel, and the first slow-start circuit 33 includes a second switch K2 and a current-limiting resistor R2 connected in series, so that the on-off state of the circuit between the input capacitor circuit 31 and the AC power supply can be adjusted through the first switch K1 and the second switch K2.

[0073] For example, see Figure 3 The AC-DC converter 30 is used to disconnect one or more first switches K1 and one or more second switches K2 in the first slow-start circuit 33 when the AC-DC converter circuit 32 is in standby mode. In this way, the circuit between the AC power supply and the input capacitor circuit 31 can be disconnected, thereby preventing the input capacitor from being charged and discharged by the AC power supply when the AC-DC converter circuit 32 is in standby mode. Furthermore, the reactive power loss of the AC-DC converter 30 when the AC-DC converter circuit 32 is in standby mode can be reduced.

[0074] In addition, the AC-DC conversion device 30 is also used to: before the AC-DC conversion circuit 32 is started, first close the second switch K2 in one or more first slow-start circuits 33 so that the AC power supply pre-charges the input capacitor in the input capacitor circuit 31 through the first slow-start circuit 33, and then close the first switch K1 in parallel with the first slow-start circuit 33.

[0075] Specifically, when the AC-DC conversion circuit 32 needs to start working, the AC-DC conversion device 30 can close the second switch K2 of each first slow-start circuit 33 before the AC-DC conversion circuit 32 starts, so that the AC power supply can form a loop between the first slow-start circuit 33 and the input capacitor circuit 31, so that the AC power supply pre-charges the input capacitor. When the second switch K2 is closed, the current limiting resistor R connected in series with the second switch K2 is used to limit the current, which can prevent the second switch K2 from generating a large impact current due to the large voltage difference between the two ends of the second switch K2 connected to the input capacitor. This is conducive to preventing the second switch K2 from being damaged due to the impact of a large current, and ensuring the normal pre-charging process of the input capacitor.

[0076] Furthermore, as the first slow-start circuit 33 performs the pre-charging process for the input capacitor, the voltage across the input capacitor increases, and the difference between the voltage across the input capacitor and the output voltage of the AC power supply decreases. In this way, in the loop formed by the input capacitor circuit 31 and the AC power supply, the current flowing through the first slow-start circuit 33 decreases, and the voltage difference across the first slow-start circuit 33 decreases accordingly. Correspondingly, the voltage difference across the first switch K1 connected in parallel with the first slow-start circuit 33 decreases. In this case, closing the first switch K1 can alleviate the problem of a large impact current on the first switch K1 due to the large voltage difference across the first switch K1. After the first switch K1 is closed, the AC power supply supplies power to the AC-DC conversion circuit 32 through the first switch K1 and the input capacitor circuit 31, so that the AC-DC conversion circuit 32 starts to work. Furthermore, the AC-DC conversion circuit 32 can be prevented from being subjected to a large current impact at startup, thereby improving the circuit operation stability of the AC-DC conversion device 30.

[0077] In addition, since the above technical solution can alleviate the problem of generating a large impact current when the first switch K1 and the second switch K2 are closed, the first switch K1 and the second switch K2 can use relays with a lower impact current tolerance than the contactor. Compared with the contactor, the cost of the relay is lower, which is more conducive to the cost optimization of the AC-DC conversion device 30.

[0078] The specific configuration of one or more input capacitors in the input capacitor circuit 31 in the AC-DC converter 30 mentioned above is exemplarily described below.

[0079] Figures 4 to 6 An example provided in the embodiment of the present application is Figure 3 A schematic diagram of the specific structure of the AC-DC conversion device 30 is shown.

[0080] In some embodiments, see Figure 4When the AC-DC conversion circuit 32 is a single-phase AC-DC conversion circuit, the input capacitor circuit 31 includes two input terminals, two output terminals and an input capacitor, and the AC-DC conversion device 30 includes a first slow-start circuit 33 and a first switch K1. That is, the input capacitor circuit 31 includes a live input terminal 31 L , neutral line input terminal 31n, live line output terminal 31' L , the neutral line output terminal 31'n and the input capacitor C L The AC-DC converter 30 includes a first switch K1 connected in parallel L And the first slow start circuit 33 L , the first slow-start circuit 33 L A second switch K2 is included in series L and current limiting resistor R L .

[0081] Among them, the live input terminal 31 L For passing through the first parallel switch K1 L And the first slow start circuit 33 L The live wire L of the AC power supply is connected, and the neutral wire input terminal 31n is used to connect the neutral wire N of the AC power supply, and the live wire output terminal 31' L The live and neutral line output terminals 31'n are connected to the live and neutral line input terminals of the AC-DC conversion circuit 32. L Connect one end of the live wire input terminal 31 L and live output terminal 31' L , input capacitance C L The other end is connected to the neutral line input terminal 31n and the neutral line output terminal 31'n.

[0082] Based on the above design, before the AC-DC conversion circuit 32 is started, the second switch K2 is closed. L , the AC power supply can be made into an input capacitor C L Pre-charge.

[0083] It should be understood that the live wire input terminal 31 L For passing through the first parallel switch K1 L And the first slow start circuit 33 L The live wire L connected to the AC power source is only an example. For example, in some other embodiments, the neutral line input terminal 31n can be used to connect the first switch K1 in parallel. L And the first slow start circuit 33 L Connect the neutral line N of the AC power supply.

[0084] It should also be understood that the input capacitor circuit 31 includes one input capacitor for example only. In some other embodiments, the input capacitor circuit 31 may also include multiple input capacitors, and the connection method of each input capacitor is similar to that of the input capacitor C. L In addition, other components may be connected between multiple input capacitors, for example, different input capacitors may be connected via common-mode inductors.

[0085] In some other embodiments, see Figure 5 When the AC-DC conversion circuit 32 is a three-phase AC-DC conversion circuit and adopts three-phase four-wire, the input capacitor circuit 31 includes four input terminals, four output terminals and three input capacitors, and the AC-DC conversion device 30 includes three first slow-start circuits 33 and three first switches K1. That is, the input capacitor circuit 31 includes an A-phase input terminal 31a, a B-phase input terminal 31b, a C-phase input terminal 31c and a neutral line input terminal 31n, an A-phase output terminal 31'a, a B-phase output terminal 31'b, a C-phase output terminal 31'c and a neutral line output terminal 31'n, and an input capacitor Ca, an input capacitor Cb and an input capacitor Cc. The AC-DC conversion device 30 includes a first switch K1a and a first slow-start circuit 33a connected in parallel, a first switch K1b and a first slow-start circuit 33b connected in parallel, and a first switch K1c and a first slow-start circuit 33c connected in parallel.

[0086] Among them, the A-phase input terminal 31a, the B-phase input terminal 31b, and the C-phase input terminal 31c are used to be connected to the A-phase line Ua, the B-phase line Ub, and the C-phase line Uc of the AC power supply through the above-mentioned set of parallel first switches K1 and the first slow-start circuit 33. The zero-line input terminal 31n is used to connect the zero-phase line N of the AC power supply. One end of the input capacitor Ca is connected to the A-phase input terminal 31a and the A-phase output terminal 31'a, one end of the input capacitor Cb is connected to the B-phase input terminal 31b and the B-phase output terminal 31'b, and so on. The other ends of the input capacitors Ca, Cb, and Cc are connected to the zero-line input terminal 31n and the zero-line output terminal 31'n.

[0087] In addition, the AC-DC conversion circuit 32 includes a three-phase rectifier bridge arm (e.g., an A-phase rectifier bridge arm, a B-phase rectifier bridge arm, and a C-phase rectifier bridge arm) and a bus capacitor circuit, and the three-phase rectifier bridge arm is used to convert the received AC power into DC power. The bus capacitor circuit includes a bus capacitor or multiple bus capacitors connected in series, such as Figure 5 The bus capacitor circuit is exemplarily shown to include a bus capacitor C1 and a bus capacitor C2 connected in series.

[0088] Among them, the A-phase rectifier bridge arm, the B-phase rectifier bridge arm, the C-phase rectifier bridge arm and the bus capacitor circuit are connected in parallel, the midpoint of the A-phase rectifier bridge arm, the midpoint of the B-phase rectifier bridge arm and the midpoint of the C-phase rectifier bridge arm are used as the three-phase input terminals of the AC-DC conversion circuit 32 and are correspondingly connected to the A-phase output terminal 31'a, the B-phase output terminal 31'b, and the C-phase output terminal 31'c of the input capacitor circuit 31, and the two ends of the bus capacitor circuit serve as the output terminals of the AC-DC conversion circuit 32. The bridge arm midpoint P of the bus capacitor circuit is connected to the zero line output terminal 31'n in the input capacitor circuit 31.

[0089] Based on the above design, before the AC-DC conversion circuit 32 is started, by closing the second switch K2a, the second switch K2b and the second switch K2c, the AC power supply can pre-charge the three input capacitors in the input capacitor circuit 31.

[0090] It should be understood that the connection positions of the above-mentioned three first switches K1 and the corresponding three first slow-start circuits 33 are only for reference. In the embodiment of the present application, as long as three of the four input terminals of the input capacitor circuit 31 are connected to the AC power supply through the first switch K1 and the first slow-start circuit 33 connected in parallel, it will be sufficient.

[0091] It should also be understood that the above-mentioned input capacitor circuit 31 including three input capacitors is only an example and is not a limitation of the present application. For example, in some other embodiments, the input capacitor circuit 31 includes multiple groups of input capacitors, each group of input capacitors includes three input capacitors, and the connection method of each group of input capacitors is the same as the above-mentioned Figure 5 The connection methods of the input capacitors Ca, Cb and Cc are the same and will not be described again here.

[0092] In some other embodiments, see Figure 6 When the AC-DC conversion circuit 32 is a three-phase AC-DC conversion circuit and adopts three-phase three-wire, the input capacitor circuit 31 includes three input terminals, three output terminals and three input capacitors, and the AC-DC conversion device 30 includes three first slow-start circuits 33 and three first switches K1. That is, the input capacitor circuit 31 includes an A-phase input terminal 31a, a B-phase input terminal 31b, a C-phase input terminal 31c, an A-phase output terminal 31'a, a B-phase output terminal 31'b, a C-phase output terminal 31'c, and an input capacitor Ca, an input capacitor Cb and an input capacitor Cc. The AC-DC conversion device 30 includes a first switch K1b and a first slow-start circuit 33b connected in parallel, and a first switch K1c and a first slow-start circuit 33c connected in parallel.

[0093] Among them, the B-phase input terminal 31b and the C-phase input terminal 31c are used to be connected to the B-phase line Ub and the C-phase line Uc of the AC power supply through the above-mentioned set of parallel first switches K1 and the first slow-start circuit 33. The A-phase input terminal 31a is used to connect the A-phase line Ua of the AC power supply. One end of the input capacitor Ca is connected to the A-phase input terminal 31a and the A-phase output terminal 31'a and the B-phase input terminal 31b and the B-phase output terminal 31'b, and one end of the input capacitor Cb is connected to the B-phase input terminal 31b and the B-phase output terminal 31'b and the C-phase input terminal 31c and the C-phase output terminal 31'c, and so on. The connection method of the three output terminals of the input capacitor circuit 31 and the AC-DC conversion circuit 32 can be seen in Figure 5 The relevant description of the illustrated embodiment will not be repeated here.

[0094] Based on the above design, before the AC-DC conversion circuit 32 is started, by closing the second switch K2b and the second switch K2c, the AC power supply can pre-charge the three input capacitors in the input capacitor circuit 31.

[0095] It should be understood that the incomplete details of the AC-DC conversion circuit 32 can be found in Figure 5 The relevant description of the illustrated embodiment will not be repeated here.

[0096] Below Figure 6 The AC-DC conversion circuit 32 shown uses a three-phase three-wire AC-DC conversion circuit as an example to exemplify the specific process of precharging the input capacitor in the input capacitor circuit 31. It should be understood that the following specific process of precharging the input capacitor in the input capacitor circuit 31 is also applicable to AC-DC conversion circuits 32 using single-phase AC-DC conversion circuits, three-phase four-wire AC-DC conversion, or other multi-phase AC-DC conversion circuits.

[0097] In some embodiments, the AC-DC conversion device 30 is used to first close the second switch K2 in one or more first slow-start circuits 33 before the AC-DC conversion circuit 32 is started, so that the AC power supply pre-charges the input capacitor in the input capacitor circuit 31 through the first slow-start circuit 33, and then closes the first switch K1 connected in parallel with the first slow-start circuit 33, including: the AC-DC conversion device 30 is used to close the first switch K1 connected in parallel with the first slow-start circuit 33 when the voltage across the input capacitor connected to the second switch K2 of the first slow-start circuit 33 is greater than or equal to the first preset voltage.

[0098] Specifically, if Figure 6As shown, when the AC-DC conversion circuit 32 needs to start working, the AC-DC conversion device 30 can close the second switch K2b and the second switch K2c before the AC-DC conversion circuit 32 starts, so that the AC power supply pre-charges the input capacitor Ca, the input capacitor Cb and the input capacitor Cc through the first slow-start circuit 33b and the first slow-start circuit 33c.

[0099] As the pre-charging process proceeds, the voltage across the input capacitor Ca and the voltage across the input capacitor Cb continue to increase. When the voltage across the input capacitor Ca connected to the second switch K2b and the voltage across the input capacitor Cb are both greater than or equal to the first preset voltage, the voltage difference across the first slow-start circuit 33b is small, that is, the voltage difference across the first switch K1b connected in parallel with the first slow-start circuit 33b is small. At this time, closing the first switch K1b will not generate a large inrush current.

[0100] Similarly, when the voltage across the input capacitor Cb connected to the second switch K2c and the voltage across the input capacitor Cc are both greater than or equal to the first preset voltage, the voltage difference across the first switch K1c connected in parallel with the first slow-start circuit 33c is small. At this time, closing the first switch K1c will not generate a large inrush current. After the first switch K1b and the first switch K1c are closed, the AC power supply transmits AC power to the AC-DC conversion circuit 32 through the first switch K1b, the first switch K1c and the input capacitor circuit 31, and the AC-DC conversion circuit 32 starts to work.

[0101] It should be understood that, in specific implementation, the first preset voltage can be flexibly adjusted according to actual needs, as long as the specific value of the first preset voltage satisfies that the first switch K connected to the input capacitor will not generate a large impact current when closed.

[0102] In the above technical solution, before the AC-DC conversion circuit 32 is started, the input capacitor is pre-charged by the first slow-start circuit 33 until the voltage across the input capacitor is greater than or equal to the first preset voltage. When the voltage across the input capacitor is greater than or equal to the first preset voltage, the voltage difference across the first switch K1 connected to the input capacitor is small, so no large impact current is generated when the first switch K1 is closed. In addition, the circuit operation stability of the AC-DC conversion device 30 can be improved.

[0103] In some embodiments, see Figure 6The AC-DC conversion device 30 is also used for: before the AC-DC conversion circuit 32 is started, after the first switch K1 is closed, the second switch K2 in the first slow-start circuit 33 connected in parallel with the first switch K1 is disconnected; after the second switches K2 of one or more first slow-start circuits 33 in the AC-DC conversion device 30 are disconnected, controlling the AC-DC conversion circuit 32 to start.

[0104] Specifically, if Figure 6 As shown, as the AC power source pre-charges the input capacitor Ca, the input capacitor Cb, and the input capacitor Cc through the first slow-start circuit 33b and the first slow-start circuit 33c, when the voltage across the input capacitor Ca connected to the second switch K2b and the voltage across the input capacitor Cb are both greater than or equal to the first preset voltage, the first switch K1b is closed first and then the second switch K2b is opened. Similarly, when the voltage across the input capacitor Cb connected to the second switch K2c and the voltage across the input capacitor Cc are both greater than or equal to the first preset voltage, the first switch K1c is closed first and then the second switch K2c is opened.

[0105] Further, after the second switch K2b and the second switch K2c are both turned off, the AC-DC conversion device 30 controls the AC-DC conversion circuit 32 to start. At this time, the AC power supply supplies power to the AC-DC conversion circuit 32 through the first switch K1b and the first switch K1c. As a result, when the AC-DC conversion circuit 32 is working, the power consumption when the AC power output by the AC power supply flows to the AC-DC conversion circuit 32 through the current limiting resistor in the first slow-start circuit 33 can be reduced, thereby improving the power utilization rate of the AC-DC conversion device 30.

[0106] Figure 7 This is another example provided in the embodiment of the present application. Figure 3 The specific structural diagram of the AC-DC converter 30 is shown in FIG. Figure 6 The embodiment shown is different in that Figure 7 In the illustrated embodiment, the AC-DC converter 30 further includes a third switch K3 , and one of the multiple input terminals of the input capacitor circuit 31 that is not connected to the first switch K1 is used to connect to an AC power source through the third switch K3 .

[0107] For example, Figure 7 As shown, when the B-phase input terminal 31b and the C-phase input terminal 31c in the input capacitor circuit 31 are connected to the AC power supply through the first switch K1b and the first switch K1c respectively, the A-phase input terminal 31a in the input capacitor circuit 31 is used to connect the AC power supply through the third switch K3. The third switch K3 is used to disconnect or connect the circuit between the A-phase input terminal 31a connected to the third switch K3 and the AC power supply.

[0108] In some embodiments, the AC-DC conversion device 30 is used to first close the third switch K3 and then close the second switch K2 in one or more first slow-start circuits 33 before the AC-DC conversion circuit 32 is started.

[0109] Specifically, if Figure 7 As shown, when the AC-DC conversion circuit 32 needs to start working, the AC-DC conversion device 30 can close the third switch K3 before the AC-DC conversion circuit 32 starts. When the third switch K3 is closed, the first switch K1b, the first switch K1c, and the second switch K2b, the second switch K2c connected to the B-phase input terminal 31b and the C-phase input terminal 31c are all in a disconnected state, so the loop between the input capacitor circuit 31 and the AC power supply is disconnected, and no AC current is generated between the AC power supply and the input capacitor circuit 31. In other words, no impact current is generated between the AC power supply and the input capacitor circuit 31 at the moment when the third switch K3 is closed, thereby improving the circuit operation stability of the charging pile.

[0110] Furthermore, the AC-DC converter 30 can close the second switch K2b and the second switch K2c after the third switch K3 is closed, so that the AC power supply pre-charges the three input capacitors in the input capacitor circuit 31 through the third switch K3, the first slow-start circuit 33b and the first slow-start circuit 33c.

[0111] It should be understood that, in a specific implementation, each phase rectifier bridge arm in the AC-DC conversion circuit 32 generally includes two diodes connected in series, or includes a switch tube connected in series, and each switch tube is connected in parallel with a diode. In this way, after the second switch K2 is closed, the AC power output by the AC power supply can not only pre-charge the input capacitor in the input capacitor circuit 31 through the first slow-start circuit 33, but also flow to the AC-DC conversion circuit 32 through the first slow-start circuit 33 and the input capacitor circuit 31, thereby pre-charging each bus capacitor in the bus capacitor circuit through the diode in the AC-DC conversion circuit 32.

[0112] For example, in some embodiments, Figure 7 Taking the AC-DC converter 30 shown in FIG. 1 as an example, when the bus capacitor circuit includes one bus capacitor, the rated capacity of the one bus capacitor is greater than the sum of the rated capacities of the input capacitors in the input capacitor circuit 31. Alternatively, when the bus capacitor circuit includes multiple bus capacitors connected in series, the equivalent rated capacity of the multiple bus capacitors is greater than the sum of the rated capacities of the input capacitors in the input capacitor circuit 31. That is, Figure 7 The equivalent rated capacities of the bus capacitors C1 and C2 shown are greater than the sum of the rated capacities of the three input capacitors in the input capacitor circuit 31 .

[0113] Among them, the AC-DC conversion device 30 is used to first close the second switch K2 in one or more first slow-start circuits 33 before the AC-DC conversion circuit 32 is started, so that the AC power supply pre-charges the input capacitor in the input capacitor circuit 31 through the first slow-start circuit 33, and then closes the first switch K1 connected in parallel with the first slow-start circuit 33, including: when the voltage across the bus capacitor circuit is greater than or equal to the second preset voltage, close the first switch K1 connected in parallel with one or more first slow-start circuits 33.

[0114] It should be understood that in the embodiment of the present application, the equivalent rated capacity of multiple bus capacitors connected in series in the bus capacitor circuit is equal to the reciprocal of the sum of the reciprocals of the rated capacities of the multiple bus capacitors.

[0115] Specifically, if Figure 7 As shown, after the AC-DC conversion device 30 closes the second switch K2b and the second switch K2c, the AC power source pre-charges the three input capacitors in the input capacitor circuit 31 through the first slow-start circuit 33b and the first slow-start circuit 33c, and the AC power output by the AC power source can also be transmitted to the three-phase rectifier bridge arm of the AC-DC conversion circuit 32 through the input capacitor circuit 31, and then pre-charges the bus capacitor C1 and the bus capacitor C2 through the diodes in the three-phase rectification. In this way, the voltage difference between the first switch K1b and the second switch K1c can be reduced, and the voltage between the two ends of the bus capacitor circuit can also be increased. In the above pre-charging process, the current is limited by the current limiting resistor Rb and the current limiting resistor Rc, which can effectively prevent the generation of a large impact current due to the large voltage difference between the second switch K2b and the second switch K2c.

[0116] It should be understood that when the AC-DC conversion circuit 32 does not receive AC power, the bus capacitor C1 and the bus capacitor C2 may discharge, resulting in a low voltage at both ends of the bus capacitor circuit, for example, the voltage at both ends of the bus capacitor circuit may drop to zero. When the AC-DC conversion circuit 32 receives AC power, the three-phase rectifier bridge arm in the AC-DC conversion circuit 32 can convert the AC power output by the AC power supply into DC power and apply it to both ends of the bus capacitor circuit. Since the DC voltage applied by the three-phase rectifier bridge arm may differ greatly from the voltage at both ends of the bus capacitor circuit when the AC power is not received, it is easy to cause the AC-DC conversion circuit 32 to generate a large inrush current when starting and powering on.

[0117] Therefore, in the embodiment of the present application, before the AC-DC conversion circuit 32 is powered on, the AC power supply is first used to pre-charge the bus capacitor through the first slow-start circuit 33, so that the voltage at both ends of the bus capacitor circuit can be increased. Furthermore, when the AC-DC conversion circuit 32 is started, the difference between the DC voltage applied by the three-phase rectifier bridge arm and the voltage at both ends of the bus capacitor circuit can be reduced, thereby preventing a large inrush current from being generated in the AC-DC conversion circuit 32 due to the low voltage at both ends of the bus capacitor circuit.

[0118] In addition, since the equivalent rated capacity of the bus capacitor C1 and the bus capacitor C2 is greater than the sum of the rated capacities of the three input capacitors in the input capacitor circuit 31, the pre-charging time required for the bus capacitor C1 and the bus capacitor C2 is generally greater than the pre-charging time required for the three input capacitors in the input capacitor circuit 31. In this way, when the voltage across the bus capacitor circuit is pre-charged to the required preset voltage, the voltage across each input capacitor in the input capacitor circuit 31 has also been pre-charged to the required voltage. For example, when the voltage across the bus capacitor circuit is pre-charged to the second preset voltage, the voltage across each input capacitor has also been pre-charged to a voltage greater than or equal to the first preset voltage.

[0119] In this case, the voltage difference between the first switch K1b and the first switch K1c is small, and no large inrush current will be generated when the first switch K1b and the first switch K1c are closed. In addition, the voltage difference between the voltage across the bus capacitor circuit and the DC voltage reapplied by the three-phase rectifier bridge arm is small, and no large inrush current will be generated when the AC-DC conversion circuit 32 is started. In turn, the circuit operation stability of the AC-DC conversion device 30 is improved.

[0120] It should be understood that in the embodiment of the present application, the second preset voltage is less than or equal to the peak voltage of the AC-DC conversion device 30 after uncontrolled rectification.

[0121] It should also be understood that, in a specific implementation, when the equivalent rated capacity of the bus capacitor C1 and the bus capacitor C2 is large, in order to prevent the bus capacitor circuit from generating a large inrush current when the AC-DC conversion circuit 32 is started and powered on, the AC power supply needs to work for a longer time through the first slow-start circuit 33b and the first slow-start circuit 33c to pre-charge the bus capacitor C1 and the bus capacitor C2, and the longer working time is likely to result in a larger energy loss in the first slow-start circuit 33b and the first slow-start circuit 33c.

[0122] Although the problem of large energy loss of the first slow-start circuit 33b and the first slow-start circuit 33c can be alleviated to a certain extent by increasing the resistance value of the current-limiting resistor Rb and the current-limiting resistor Rc, or increasing the number of the current-limiting resistors, increasing the resistance value of the current-limiting resistor or increasing the number of the current-limiting resistors is likely to increase the power loss of the current-limiting resistor, resulting in reduced efficiency of the AC-DC converter 30. In this case, a separate slow-start circuit can be added to pre-charge the bus capacitor in the bus capacitor circuit separately.

[0123] For example, see Figure 8 , Figure 8 Another example provided in the embodiment of the present application Figure 3 The specific structural diagram of the AC-DC converter 30 is shown in FIG. Figure 8 As shown, the AC-DC conversion device 30 also includes a second slow-start circuit 34, which is connected to both ends of the bus capacitor circuit of the AC-DC conversion circuit 32, and is used to pre-charge each bus capacitor in the bus capacitor circuit.

[0124] Among them, the AC-DC conversion device 30 is used to control the second slow-start circuit 34 to pre-charge each bus capacitor in the bus capacitor circuit of the AC-DC conversion circuit 32 before the AC-DC conversion circuit 32 is started, and then close the second switch K2 in one or more first slow-start circuits 33 of the AC-DC conversion device 30.

[0125] Specifically, if Figure 8 As shown, when the AC-DC conversion circuit 32 needs to start working, the AC-DC conversion device 30 can first control the second slow-start circuit 34 to pre-charge the bus capacitor C1 and the bus capacitor C2 in the bus capacitor circuit. As the pre-charging process proceeds, the voltage across the bus capacitor circuit increases, and the voltage difference between the voltage across the bus capacitor circuit and the DC voltage applied by the three-phase rectifier bridge arm decreases. Afterwards, the AC-DC conversion device 30 closes the second switch K2b and the second switch K2c to continue charging the bus capacitor C1 and the bus capacitor C2 through the first slow-start circuit 33b and the first slow-start circuit 33c, thereby further reducing the voltage difference between the voltage across the bus capacitor circuit and the DC voltage applied by the three-phase rectifier bridge arm.

[0126] Therefore, when the equivalent rated capacity of the bus capacitor C1 and the bus capacitor C2 is large, the duration of the first slow-start circuit 33b and the first slow-start circuit 33c precharging the voltage across the bus capacitor circuit to the required voltage can be reduced, thereby reducing the energy loss of the first slow-start circuit 33b and the first slow-start circuit 33c during operation.

[0127] Furthermore, in some embodiments, the AC-DC conversion device 30 is used to control the second slow-start circuit 34 to pre-charge each bus capacitor in the bus capacitor circuit of the AC-DC conversion circuit 32 before the AC-DC conversion circuit 32 is started, and then close the second switch K2 in one or more first slow-start circuits 33 of the AC-DC conversion device 30, including: the AC-DC conversion device 30 is used to close the second switch K2 in one or more first slow-start circuits 33 of the AC-DC conversion device 30 when the voltage across the bus capacitor circuit is greater than a third preset voltage.

[0128] In the above technical solution, when the voltage at both ends of the bus capacitor circuit in the AC-DC conversion circuit 32 is precharged to a voltage greater than the third preset voltage, the voltage difference between the voltage at both ends of the bus capacitor circuit and the DC voltage applied by the three-phase rectifier bridge arm is small. At this time, even if the bus capacitor is not precharged through the first slow-start circuit 33, the bus capacitor circuit can be prevented from generating a large impact current when the AC-DC conversion circuit 32 is started. Therefore, when the voltage at both ends of the bus capacitor circuit is precharged to a voltage greater than the third preset voltage, the second switch is closed, and the process of precharging the bus capacitor by the first slow-start circuit 33 can be ignored. The first slow-start circuit 33 can only be used to precharge the input capacitor, and the second switch can be disconnected when the voltage at both ends of the input capacitor is precharged to a voltage greater than or equal to the first preset voltage. In this way, the problem of large energy loss of the first slow-start circuit during operation due to the long duration of the AC power supply precharging the bus capacitor through the first slow-start circuit can be prevented.

[0129] Exemplarily, the third preset voltage may be a peak voltage of the output voltage of the AC power source.

[0130] It should be understood that in actual application, the anode of the diode in the three-phase rectifier bridge arm of the AC-DC conversion circuit 32 is usually connected to the input end of the AC-DC conversion circuit 32, and the cathode of the diode is usually connected to the bus capacitor circuit. Therefore, when the voltage across the bus capacitor circuit is precharged to a peak voltage greater than the output voltage of the AC power supply, the diode in the AC-DC conversion circuit 32 is reversely cut off, and the bus capacitor circuit and the three-phase rectifier bridge arm are disconnected. In this case, the AC-DC conversion device 30 closes the second switch K2b and the second switch K2c to precharge the input capacitor, which can effectively prevent the precharge current flowing through the first slow-start circuit 33b and the first slow-start circuit 33c from lasting for a long time and causing excessive impact energy due to precharging the bus capacitor C1 and the bus capacitor C2. Further, when the voltage across the input capacitor of the input capacitor circuit 31 is precharged to a voltage greater than or equal to the first preset voltage, the first switch K1b and the first switch K1c are closed.

[0131] In some embodiments, see Figure 8 When one input end of the input capacitor circuit 31 is connected to an AC power source through the third switch K3, the AC-DC converter 30 is used to control the second slow-start circuit 34 to pre-charge each bus capacitor in the bus capacitor circuit before the AC-DC converter circuit 32 is started, and then close the third switch K3, and then close the second switch K2 in one or more first slow-start circuits 33 of the AC-DC converter 30.

[0132] Based on the above design, it is possible to prevent the problem of large energy loss of the first slow-start circuit 33 during operation due to the long duration of the AC power supply pre-charging the bus capacitor through the first slow-start circuit 33b, and it is also possible to ensure that no impact current is generated between the AC power supply and the input capacitor circuit 31 at the moment when the third switch K3 is closed, thereby improving the circuit operation stability of the AC-DC conversion device 30.

[0133] The AC-DC converter 30 provided in the embodiment of the present application is introduced above. The charging pile provided in the embodiment of the present application is introduced below. Fig. 9 It is a structural schematic diagram of a charging pile 40 provided in an embodiment of the present application.

[0134] See also Fig. 9 The charging pile 40 includes the AC-DC converter 30 and the charging gun 43 described above. The AC-DC converter 30 is used to convert the AC power output by the AC power source into DC power and then output it to the charging gun 43, so as to charge the electric vehicle through the charging gun 43. For a detailed description of the AC-DC converter 30, please refer to Figures 3 to 8 The relevant description of the illustrated embodiment will not be repeated here.

[0135] In some embodiments, the charging pile 40 further includes a DC bus 41 and a DC-DC converter 42. The AC-DC converter 30 is used to convert the AC power output by the AC power source into DC power and then output it to the DC bus 41, and the DC-DC converter 42 is used to convert the DC power obtained from the DC bus 41 into power and then output it to the charging gun 43.

[0136] It should be understood that the number of AC-DC converters 30 and DC-DC converters 42 in the charging pile 40 can be multiple, and the number of AC-DC converters 30 and DC-DC converters 42 can be the same or different.

[0137] For details on the connection between the AC-DC converter 30, the DC-DC converter 42 and the charging gun 43 in the charging pile 40, see Figure 1 and Figure 2 The relevant description of the illustrated embodiment will not be repeated here.

[0138] The structure of the charging pile 40 is further described in detail below.

[0139] Fig.10 This is an example provided in the embodiment of the present application. Fig. 9 A schematic diagram of the specific structure of the charging pile 40 is shown.

[0140] In some embodiments, see Fig.10 In the charging pile 40, each AC-DC conversion device 30 includes a second slow-start circuit 34, which is connected to the bus capacitor circuit in the AC-DC conversion device 30, and the second slow-start circuit 34 is used to pre-charge each bus capacitor in the bus capacitor circuit.

[0141] In a specific implementation, the charging pile 40 is used to control the second slow-start circuit 34 to pre-charge each bus capacitor in the bus capacitor circuit before the AC-DC conversion circuit 32 in the AC-DC conversion device 30 is started, and then close the second switch K2 in one or more first slow-start circuits 33 in the AC-DC conversion device 30. In this way, the voltage across the bus capacitor circuit can be increased, thereby reducing the duration of the AC power supply charging the bus capacitor through the first slow-start circuit 33. Furthermore, the energy loss of the first slow-start circuit 33 during operation can be reduced.

[0142] For a detailed description of the second slow-start circuit 34, please refer to Figure 8 The relevant description of the illustrated embodiment will not be repeated here.

[0143] In the above technical solution, the second slow-start circuit 34 provided in the AC-DC converter 30 is connected to the bus capacitor circuit, so that when there are multiple AC-DC converters 30 in the charging pile 40, each AC-DC converter 30 can pre-charge its own bus capacitor through its own second slow-start circuit 34. Fig.10 As shown, the two AC-DC converters 30 in the charging pile 40 can pre-charge their respective bus capacitors through their respective second slow-start circuits 34, that is, the pre-charging process of the bus capacitors of the two AC-DC converters 30 is performed independently. This can improve the circuit operation reliability of the two AC-DC converters 30.

[0144] Fig.11 This is another example provided in the embodiment of the present application. Fig. 9 A schematic diagram of the specific structure of the charging pile 40 is shown.

[0145] and Fig.10 Each AC-DC converter 30 in the charging pile 40 shown includes a second slow-start circuit 34. Fig.11In the illustrated embodiment, a second slow-start circuit for precharging the bus capacitor circuit of each AC-DC conversion device 30 is separately provided in the charging pile 40 .

[0146] For example, Fig.11 As shown, in some embodiments, the charging pile 40 further includes a DC bus 41, and the number of AC-DC conversion devices 30 in the charging pile 40 is multiple, and the multiple AC-DC conversion devices 30 are connected in parallel to the DC bus 41. Specifically, the AC-DC conversion circuit 32 in each AC-DC conversion device 30 is used to output the converted DC power to the DC bus 41 through the bus capacitor circuit, and the DC bus is connected to the charging gun 43.

[0147] In addition, the charging pile 40 also includes a second slow-start circuit 44, which is connected to the DC bus 41 and is used to pre-charge each bus capacitor in the bus capacitor circuit of the AC-DC conversion device 30 through the DC bus 41.

[0148] In a specific implementation, the charging pile 40 is used to control the second slow-start circuit 34 to pre-charge each bus capacitor in the bus capacitor circuit in the AC-DC converter 30 through the DC bus 41 before the AC-DC converter circuit 32 in the AC-DC converter 30 is started, and then close the second switch K2 in one or more first slow-start circuits 33 in the AC-DC converter 30. In this way, the voltage across the bus capacitor circuit can be increased, thereby reducing the duration of the AC power supply charging the bus capacitor through the first slow-start circuit 33. Furthermore, the energy loss of the first slow-start circuit 33 during operation can be reduced.

[0149] It should be understood that the specific process of the second slow-start circuit 44 precharging the bus capacitor in the AC-DC converter 30 is similar to the process of the second slow-start circuit 34 precharging the bus capacitor in the AC-DC converter 30 in which it is located. For a specific description, see Figure 8 The relevant description of the illustrated embodiment will not be repeated here.

[0150] In the above technical solution, by connecting the second slow-start circuit 44 to the DC bus 41, the second slow-start circuit 44 can pre-charge the bus capacitor of each AC-DC conversion device 30 in the charging pile 40 through the DC bus 41. Fig.11 As shown, the second slow-start circuit 44 can pre-charge each bus capacitor in the bus capacitor circuits in the two AC-DC converters 30 through the DC bus 41. This can reduce the number of slow-start circuits in the charging pile 40 that pre-charge the bus capacitors of multiple AC-DC converters 30, thereby reducing the complexity of the circuit design in the charging pile 40, which is beneficial to the cost optimization of the charging pile 40.

[0151] Further, in some embodiments, in combination Fig.10 and Fig.11 The charging pile 40 is used to control the second slow-start circuit 34 to pre-charge each bus capacitor in the bus capacitor circuit before the AC-DC conversion circuit 32 in the AC-DC conversion device 30 is started, and then close the second switch K2 in one or more first slow-start circuits 33 in the AC-DC conversion device 30, including: the charging pile 40 is used to close the second switch in one or more first slow-start circuits 33 in the AC-DC conversion device 30 when the voltage across the bus capacitor circuit in the AC-DC conversion device 30 is greater than a third preset voltage.

[0152] In the above technical solution, when the voltage across the bus capacitor circuit in the AC-DC converter 30 is pre-charged to a voltage greater than the third preset voltage, the voltage difference between the voltage across the bus capacitor circuit and the DC voltage applied by the three-phase rectifier bridge arm is small. At this time, the first slow-start circuit 33 can be used only to pre-charge the input capacitor in the AC-DC converter 30, thereby preventing the problem of large energy loss of the first slow-start circuit 33 during operation due to the long duration of pre-charging the bus capacitor by the first slow-start circuit 33. For a detailed description, please refer to Figure 8 The relevant description of the illustrated embodiment will not be repeated here.

[0153] In some embodiments, in combination Figures 9 to 11 The charging pile 40 further includes a plurality of DC-DC converters 42, which are connected in parallel to the DC bus 41, and the DC bus 41 is connected to the charging gun 43 through the plurality of DC-DC converters 42. The charging pile 40 is used to control the DC-DC converter 42 to start after the AC-DC converter circuits 32 of the plurality of AC-DC converters 30 are started.

[0154] For example, Figures 9 to 11 As shown, taking the charging pile 40 including two AC-DC converters 30 and two DC-DC converters 42 as an example, the charging pile 40 can start the two DC-DC converters 42 after the AC-DC converter circuits 32 in the two AC-DC converters 30 are started. In this way, it is possible to prevent the safety problem caused by the surge current generated when the AC-DC converter circuit 32 in the AC-DC converter 30 is started after the DC-DC converter 42 is started, flowing through the already started DC-DC converter 42.

[0155] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. An AC-DC converter, characterized in that: The AC-DC conversion device comprises an input capacitor circuit, an AC-DC conversion circuit, one or more first switches and one or more first slow-start circuits, wherein the multiple input terminals of the input capacitor circuit are used to connect to an AC power source, and the AC-DC conversion circuit is used to convert the AC power output from the input capacitor circuit into DC power for output; wherein, Each of the multiple input terminals of the input capacitor circuit except one input terminal is used to connect the AC power source through one of the first switches; Each of the first slow-start circuits comprises a second switch and a current-limiting resistor connected in series, and each of the first slow-start circuits is connected in parallel with one of the first switches; The AC-DC conversion device is used for: When the AC-DC conversion circuit is in standby mode, disconnecting the one or more first switches and the second switches in the one or more first slow-start circuits; Before the AC-DC conversion circuit is started, the second switch in the one or more first slow-start circuits is closed first, so that the AC power supply pre-charges the input capacitor in the input capacitor circuit through the first slow-start circuit, and then the first switch connected in parallel with the first slow-start circuit is closed.

2. The AC-DC converter according to claim 1, characterized in that: The AC-DC conversion device further includes a third switch, and the one input end of the input capacitor circuit is used to connect the AC power supply through the third switch; The AC-DC conversion device is used to close the third switch first and then close the second switch in the one or more first slow-start circuits before starting the AC-DC conversion circuit.

3. The AC-DC converter according to claim 1 or 2, characterized in that: The AC-DC conversion device is also used for: Before the AC-DC conversion circuit is started, after the first switch is closed, the second switch in the first slow-start circuit connected in parallel with the first switch is disconnected; After the second switch in the one or more first slow-start circuits is disconnected, the AC-DC conversion circuit is controlled to start.

4. The AC-DC converter according to any one of claims 1 to 3, characterized in that: The AC-DC conversion device is used to reclose the first switch connected in parallel with the first slow-start circuit, and includes: The AC-DC conversion device is used to close the first switch connected in parallel with the first slow-start circuit when the voltage across the input capacitor connected to the second switch in the first slow-start circuit is greater than or equal to a first preset voltage.

5. The AC-DC converter according to any one of claims 1 to 3, characterized in that: The AC-DC conversion circuit includes a bus capacitor circuit, and the AC-DC conversion circuit is used to output the direct current through the bus capacitor circuit; wherein, The bus capacitor circuit includes a bus capacitor, the rated capacity of the bus capacitor is greater than the sum of the rated capacities of the input capacitors in the input capacitor circuit, or the bus capacitor circuit includes a plurality of bus capacitors connected in series, the equivalent rated capacities of the plurality of bus capacitors are greater than the sum of the rated capacities of the input capacitors in the input capacitor circuit; The AC-DC conversion device is used to reclose the first switch connected in parallel with the first slow-start circuit, and includes: The AC-DC conversion device is used to close the first switch connected in parallel with the one or more first slow-start circuits when the voltage across the bus capacitor circuit is greater than or equal to a second preset voltage.

6. The AC-DC converter according to any one of claims 1 to 4, characterized in that: The AC-DC conversion circuit includes a bus capacitor circuit, the bus capacitor circuit includes one bus capacitor or a plurality of bus capacitors connected in series, and the AC-DC conversion circuit is used to output the direct current through the bus capacitor circuit; The AC-DC conversion device further comprises a second slow-start circuit, the second slow-start circuit is connected to the bus capacitor circuit, and the second slow-start circuit is used to pre-charge the bus capacitor in the bus capacitor circuit; The AC-DC conversion device is used to control the second slow-start circuit to pre-charge the bus capacitor in the bus capacitor circuit before starting the AC-DC conversion circuit, and then close the second switch in the one or more first slow-start circuits.

7. The AC-DC converter according to claim 6, characterized in that: The AC-DC conversion device is used to reclose the second switch in the one or more first slow-start circuits, comprising: The AC-DC conversion device is used to close the second switch in the one or more first slow-start circuits when the voltage across the bus capacitor circuit is greater than a third preset voltage.

8. A charging pile, characterized in that: The charging pile includes an AC-DC conversion device and a charging gun as described in any one of claims 1 to 3, and the AC-DC conversion device is used to convert the AC power output by the AC power supply into DC power and then output it to the charging gun.

9. The charging pile according to claim 8, characterized in that: The AC-DC conversion device is used to reclose the first switch connected in parallel with the first slow-start circuit, and includes: The AC-DC conversion device is used to close the first switch connected in parallel with the first slow-start circuit when the voltage across the input capacitor connected to the second switch in the first slow-start circuit is greater than or equal to a first preset voltage.

10. The charging pile according to claim 8, characterized in that: The AC-DC conversion circuit includes a bus capacitor circuit, and the AC-DC conversion circuit is used to output the converted direct current to the charging gun through the bus capacitor circuit; wherein, The bus capacitor circuit includes a bus capacitor, the rated capacity of the bus capacitor is greater than the sum of the rated capacities of the input capacitors in the input capacitor circuit, or the bus capacitor circuit includes a plurality of bus capacitors connected in series, the equivalent rated capacities of the plurality of bus capacitors are greater than the sum of the rated capacities of the input capacitors in the input capacitor circuit; The AC-DC conversion device is used to reclose the first switch connected in parallel with the first slow-start circuit, and includes: The AC-DC conversion device is used to close the first switch connected in parallel with the one or more first slow-start circuits when the voltage across the bus capacitor circuit is greater than or equal to a second preset voltage.

11. The charging pile according to claim 8 or 9, characterized in that: The AC-DC conversion circuit includes a bus capacitor circuit, and the AC-DC conversion circuit is used to output the converted direct current to the charging gun through the bus capacitor circuit; The AC-DC conversion device further comprises a second slow-start circuit, the second slow-start circuit is connected to the bus capacitor circuit, and the second slow-start circuit is used to pre-charge the bus capacitor in the bus capacitor circuit; The charging pile is used to control the second slow-start circuit to pre-charge the bus capacitor in the bus capacitor circuit before starting the AC-DC conversion circuit, and then close the second switch in the one or more first slow-start circuits.

12. The charging pile according to claim 8 or 9, characterized in that: The charging pile further includes a DC bus, and the number of the AC-DC conversion devices is multiple, and the multiple AC-DC conversion devices are connected to the DC bus in parallel; The AC-DC conversion circuit includes a bus capacitor circuit, and the AC-DC conversion circuit is used to output the converted direct current to the DC bus through the bus capacitor circuit, and the DC bus is connected to the charging gun; The charging pile further includes a second slow-start circuit, the second slow-start circuit is connected to the DC bus, and the second slow-start circuit is used to pre-charge the bus capacitor in the bus capacitor circuit through the DC bus; The charging pile is used to control the second slow-start circuit to pre-charge the bus capacitor in the bus capacitor circuit before starting the AC-DC conversion circuit, and then close the second switch in the one or more first slow-start circuits.

13. The charging pile according to claim 11 or 12, characterized in that: The charging pile is used to reclose the second switch in the one or more first slow-start circuits, including: The charging pile is used to close the second switch in the one or more first slow-start circuits when the voltage across the bus capacitor circuit is greater than a third preset voltage.

14. The charging pile according to claim 12, characterized in that: The charging pile further includes a plurality of DC-DC conversion devices, the plurality of DC-DC conversion devices are connected in parallel to the DC bus, and the DC bus is connected to the charging gun through the plurality of DC-DC conversion devices; The charging pile is used to control the startup of the multiple DC-DC conversion devices after the AC-DC conversion circuits in the multiple AC-DC conversion devices are started.

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