Power conversion device, charging pile, on-board charger and electric vehicle

Abstract

A power conversion device, charging pile, on-board charger, and electric vehicle are disclosed to reduce the operating cost of the power conversion device and improve its operational stability. The power conversion device includes: a first capacitor branch, comprising at least one electrolytic capacitor, for regulating the voltage received by the power conversion device to obtain a first voltage; a second capacitor branch, comprising multiple film capacitors connected in series, for filtering the first voltage and dividing the filtered first voltage to obtain multiple second voltages, with each film capacitor receiving one second voltage; and a DC-DC converter corresponding to each film capacitor, with the input terminal of each DC-DC converter connected in parallel with the corresponding film capacitor; the DC-DC converter is used to perform voltage conversion processing on the second voltages output by the film capacitors.

Description

Technical Field

[0001] This application relates to the field of power electronics technology, and in particular to a power conversion device, a charging pile, an on-board charger, and an electric vehicle. Background Technology

[0002] With the development of new energy vehicles, on-board chargers (OBCs) are being used more and more widely.

[0003] Specifically, the OBC mainly consists of a first conversion circuit and a second conversion circuit. The input of the first conversion circuit is connected to the charging pile via a charging gun, and its output is connected to the input of the second conversion circuit. The output of the second conversion circuit can be connected to the high-voltage battery of the electric vehicle. The first conversion circuit converts the AC power output from the charging pile into DC power, and the second conversion circuit converts the DC power output from the first conversion circuit into the charging voltage for the high-voltage battery, thus charging the high-voltage battery in the electric vehicle. In practical applications, as the requirements for electric vehicle charging speeds gradually increase, the second conversion circuit can include multiple DC-DC conversion modules connected in series at their inputs. Each DC-DC conversion module has at least one electrolytic capacitor connected in parallel at its input. Each parallel electrolytic capacitor receives a portion of the voltage, and each DC-DC conversion module can perform voltage conversion processing on the voltage output from the parallel electrolytic capacitor, thereby enabling each conversion module to convert a portion of the power and improving the charging efficiency of the OBC.

[0004] However, due to the limitations of the electrolytic capacitor's voltage rating, if the DC-DC converter module short-circuits, the electrolytic capacitor connected to the faulty module will also be short-circuited. Other electrolytic capacitors connected in series with this faulty module will then break down due to the high voltage, rendering the entire circuit inoperable. Therefore, current OBCs require further research. Summary of the Invention

[0005] This application provides a power conversion device, a charging pile, an on-board charger, and an electric vehicle, which can reduce the operating cost of the power conversion device and improve its operational stability.

[0006] In a first aspect, embodiments of this application provide a power conversion device, including a first capacitor branch, a second capacitor branch, and a plurality of DC-DC converters.

[0007] The first capacitor branch includes at least one electrolytic capacitor for regulating the voltage received by the power conversion device to obtain a first voltage. The second capacitor branch includes multiple film capacitors connected in series for filtering the first voltage and then dividing the filtered first voltage to obtain multiple second voltages. Each film capacitor receives one second voltage. A DC-DC converter corresponds to each film capacitor, with each converter's input terminal connected in parallel with its corresponding film capacitor. The DC-DC converter performs voltage conversion on the second voltages output by the film capacitors.

[0008] In the power conversion device described in this application, due to the high-voltage withstand capability of film capacitors, a second capacitor branch composed of film capacitors is used to filter and divide the first voltage, and a first capacitor branch composed of large-capacity electrolytic capacitors is used to stabilize the voltage received by the power conversion device. In this case, if any DC-DC converter short-circuits, the film capacitor connected in parallel at the input terminal of that DC-DC converter is bypassed. Since the amplitude of the first voltage after filtering remains unchanged, but the number of film capacitors in series decreases, the voltage across the film capacitor connected in parallel at the input terminal of the non-faulty DC-DC converter increases. However, due to the high-voltage withstand capability of film capacitors, the non-faulty DC-DC converters in the power conversion device can still operate normally, improving the operational stability of the power conversion device. Furthermore, since the cost of film capacitors is lower than that of electrolytic capacitors, when a DC-DC converter failure causes damage to the film capacitors, it also helps to reduce the maintenance costs of the power conversion circuit.

[0009] In one possible implementation, the first capacitor branch includes a first electrolytic capacitor, which is used to regulate the voltage received by the power conversion device to obtain a first voltage.

[0010] When the voltage amplitude received by the power conversion device is small, an electrolytic capacitor can be used to stabilize the voltage received by the power conversion device.

[0011] In one possible implementation, the first capacitor branch includes a plurality of second electrolytic capacitors connected in series. The plurality of second electrolytic capacitors connected in series are used to regulate the voltage received by the power conversion device to obtain the first voltage.

[0012] When the voltage amplitude received by the power conversion device exceeds the upper limit of the withstand voltage of a single electrolytic capacitor, multiple second electrolytic capacitors can be connected in series to increase their withstand voltage and meet the voltage requirements of the power conversion device.

[0013] In one possible implementation, the power conversion device further includes a resistor branch connected in parallel with the first capacitor branch.

[0014] The resistor branch includes multiple first resistors, each first resistor corresponding to each second electrolytic capacitor, and each first resistor is connected in parallel with its corresponding second electrolytic capacitor.

[0015] In the aforementioned power conversion device, due to individual differences among the multiple second electrolytic capacitors, when multiple second electrolytic capacitors are connected in series, the voltage across each second electrolytic capacitor may deviate from its operating voltage range, causing damage to the device. To address this, multiple first resistors can be connected in series to form a voltage divider branch. Each first resistor receives a portion of the voltage. Since a first resistor is connected in parallel with one second electrolytic capacitor, the voltage across the first resistor becomes the voltage across the second electrolytic capacitor connected in parallel, thereby controlling the voltage across the second electrolytic capacitor and ensuring its safe operation.

[0016] In one possible implementation, the power conversion device further includes a voltage equalization circuit connected to the first capacitor branch and performing voltage regulation on each second electrolytic capacitor.

[0017] Using the power conversion device described above, the voltage amplitude across each second electrolytic capacitor can be controlled by a voltage equalization circuit.

[0018] In one possible implementation, the outputs of multiple DC-DC converters are connected in parallel.

[0019] Using the power conversion device described above, high-power power supply or high-power charging can be achieved by connecting the output terminals of multiple DC converters in parallel.

[0020] In one possible implementation, the outputs of multiple DC-DC converters are connected in series.

[0021] When the output voltage of a single DC converter cannot meet the voltage requirements of the connected equipment, the output voltage amplitude of the power conversion device can be increased by connecting the output terminals of multiple DC converters in series.

[0022] In one possible implementation, the power conversion device also includes a protector.

[0023] The protector is used to disconnect the power conversion device from the external power supply when the input voltage or input current of the power conversion device exceeds a preset threshold.

[0024] When the above-mentioned equipment is used, if other components in the power conversion device or equipment connected to the power conversion device are damaged, resulting in overcurrent or overvoltage in the power conversion device, the power conversion device can be disconnected from the external power supply by the protector, thereby preventing the scope of the fault from expanding.

[0025] In one possible implementation, the power conversion device also includes a controller.

[0026] The controller is connected to multiple DC-DC converters and is used to adjust the voltage conversion ratio of the non-faulty DC-DC converters when it is determined that any of the DC-DC converters has failed.

[0027] When a faulty DC-DC converter is used in the power conversion device, the voltage originally received by the faulty DC-DC converter will be proportionally distributed to the non-faulty DC-DC converter, causing the input voltage of the non-faulty DC-DC converter to increase. In order to ensure that the output voltage of the DC-DC converter meets the voltage requirements of the connected equipment, the controller can adjust the turns ratio of the non-faulty DC-DC converter when a faulty DC-DC converter is found in the power conversion device.

[0028] Secondly, embodiments of this application provide a charging pile, which may include a first conversion circuit and a power conversion device provided in the first aspect of the embodiments of this application and any possible design thereof.

[0029] The first conversion circuit is connected to an external power source and converts the AC power output from the external power source into DC power. A power conversion device is connected to the first conversion circuit and performs voltage conversion on the DC power output from the first conversion circuit, using the converted DC power to supply power to the load. The external power source can be an industrial frequency grid, and the load can be a vehicle.

[0030] Thirdly, embodiments of this application provide an on-board charger, which includes a first conversion circuit and a power conversion device provided in the first aspect of the embodiments of this application and any possible design thereof.

[0031] The first conversion circuit is connected to an external power source and converts the AC power output from the external power source into DC power. A power conversion device is connected to the first conversion circuit and performs voltage conversion on the DC power output from the first conversion circuit, using the converted DC power to supply power to the load. The external power source can be a charging station, and the load can be a battery inside the vehicle.

[0032] Fourthly, embodiments of this application provide an electric vehicle, which includes a high-voltage battery, a low-voltage battery, a low-voltage load, and a power conversion device provided in the first aspect of embodiments of this application and any possible design thereof.

[0033] The high-voltage battery is connected to the power conversion device; the power conversion device is connected to the low-voltage battery and the low-voltage load respectively. The power conversion device is used to perform voltage conversion processing on the electrical energy output by the high-voltage battery and to supply power to the low-voltage battery and the low-voltage load with the voltage-converted electrical energy.

[0034] It should be understood that the technical effects that can be achieved by the various design schemes in each of the second to fourth aspects above are described in the technical effect description of the corresponding schemes in the first aspect above, and will not be repeated here. Attached Figure Description

[0035] Figure 1 This application provides a schematic diagram of the structure of an electric vehicle.

[0036] Figure 2 This is a schematic diagram of the structure of a DC-to-DC module provided in an embodiment of this application;

[0037] Figure 3 A schematic diagram of the structure of a power conversion device provided in this application embodiment. Figure 1 ;

[0038] Figure 4 A schematic diagram of the structure of a power conversion device provided in this application embodiment. Figure 2 ;

[0039] Figure 5 A schematic diagram of the structure of a first capacitor branch provided in an embodiment of this application. Figure 1 ;

[0040] Figure 6 A schematic diagram of the structure of a first capacitor branch provided in an embodiment of this application. Figure 2 ;

[0041] Figure 7 A schematic diagram of the structure of a power conversion device provided in this application embodiment. Figure 3 ;

[0042] Figure 8 A schematic diagram of the structure of a power conversion device provided in this application embodiment. Figure 4 ;

[0043] Figure 9 This is a schematic diagram of the structure of a second capacitor branch provided in an embodiment of this application;

[0044] Figure 10 This is a schematic diagram of the structure of a DC-DC converter provided in an embodiment of this application;

[0045] Figure 11 A schematic diagram of the structure of a power conversion device provided in this application embodiment. Figure 5 ;

[0046] Figure 12 A schematic diagram of the structure of a power conversion device provided in this application embodiment. Figure 6 ;

[0047] Figure 13 A schematic diagram of the structure of a power conversion device provided in this application embodiment. Figure 7 . Detailed Implementation

[0048] To make the objectives, technical solutions, and advantages of this application clearer, the application will be further described in detail below with reference to the accompanying drawings. The specific operational methods in the method embodiments can also be applied to the device embodiments or system embodiments. It should be noted that in the description of this application, "at least one" refers to one or more, where "multiple" refers to two or more. Therefore, in the embodiments of this invention, "multiple" can also be understood as "at least two". "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / ", unless otherwise specified, generally indicates that the preceding and following related objects have an "or" relationship. Furthermore, it should be understood that in the description of this application, terms such as "first" and "second" are only used for distinguishing the descriptive purpose and should not be construed as indicating or implying relative importance or order.

[0049] It should be noted that in the embodiments of this application, "connection" can be understood as electrical connection. The connection between two electrical components can be a direct or indirect connection between the two electrical components. For example, the connection between A and B can be a direct connection between A and B, or an indirect connection between A and B through one or more other electrical components, such as the connection between A and B. Alternatively, it can be a direct connection between A and C, a direct connection between C and B, with A and B connected through C.

[0050] It should be noted that the switches in this application embodiment can be one or more of various types of switching transistors, such as relays, metal oxide semiconductor field effect transistors (MOSFETs), bipolar junction transistors (BJTs), insulated gate bipolar transistors (IGBTs), and silicon carbide (SiC) transistors. These will not be listed individually in this application embodiment. The packaging of each switching transistor can be a single-transistor package or a multi-transistor package; this application embodiment does not impose any restrictions on this. Each switching transistor can include a first electrode, a second electrode, and a control electrode, wherein the control electrode is used to control the switching transistor's on or off state. When the switching transistor is on, current can be transferred between the first and second electrodes; when the switching transistor is off, no current can be transferred between the first and second electrodes. Taking a MOSFET as an example, the control electrode of the switching transistor is the gate, the first electrode can be the source, and the second electrode can be the drain, or the first electrode can be the drain and the second electrode can be the source.

[0051] It should be noted that, in the embodiments of this application, the "turns ratio" of the DC-DC converter refers to the ratio between the input voltage and the output voltage of the DC-DC converter, which can also be understood as the voltage conversion ratio. If the DC-DC converter performs buck conversion, the output voltage of the DC-DC converter is less than the input voltage of the DC-DC converter, and the turns ratio of the DC-DC converter is greater than 1. If the DC-DC converter performs boost conversion, the output voltage of the DC-DC converter is greater than the input voltage of the DC-DC converter, and the turns ratio of the DC-DC converter is less than 1.

[0052] To facilitate understanding of the power conversion device provided in the embodiments of this application, the application scenarios of the power conversion device will be introduced first below.

[0053] The power conversion device provided in this application embodiment can be applied to a power supply system or a charging system. It can convert the voltage output by the power source into the supply voltage or charging voltage required by the load, and use the supply voltage or charging voltage to supply power or charge one or more loads. For example, the power supply system can be an on-board charger (OBC) 11 in an electric vehicle, a power supply device in an electronic device, or a charging pile for an electric vehicle. The electronic device can be, but is not limited to, devices such as servers and base stations.

[0054] In a specific application scenario, the power conversion device can be used in electric vehicles, also known as new energy vehicles, which are automobiles powered by electricity. See also... Figure 1As shown, the electric vehicle 10 mainly includes an on-board charger (OBC) 11, a high-voltage battery 12, a DC-DC converter circuit 13, a low-voltage battery 14, a low-voltage load 15, a power system 16, and wheels 17. The high-voltage battery 12 and the low-voltage battery 14 are both rechargeable batteries capable of charging and discharging, such as lithium batteries or lead-acid batteries.

[0055] The power system 16 typically includes a reducer, gears, one or more motors, etc. When the electric vehicle is in motion, the high-voltage battery 12 can supply power to the power system 16, the motor in the power system 16 rotates, and drives the wheels 17 to rotate through the gears and reducer, thereby enabling the vehicle to move.

[0056] The low-voltage load 15 can be a functional system or on-board equipment inside the vehicle (electric vehicle 10). Furthermore, the rated voltage of the low-voltage load 15 is significantly lower than the rated voltage of the high-voltage battery 12. Each low-voltage load 15 may include, but is not limited to, at least one critical load and / or at least one secondary load. A critical load can be understood as a load that affects vehicle operation, such as a control system, an autonomous driving system, or an on-board navigation system. A secondary load can be understood as a load that does not affect vehicle operation, such as a car radio. In some scenarios, the low-voltage load may include multiple critical loads, and these multiple critical loads have the same function.

[0057] When charging electric vehicle 10, it can generally be charged through charging station 201.

[0058] In some scenarios, the OBC11 can be equipped with an AC-to-DC module to convert the AC power output from the power supply circuit 202 into DC power to charge the high-voltage battery 12. The OBC11 can also be equipped with a DC-to-DC module to convert the DC voltage output from the power supply circuit 202 into the charging voltage for the high-voltage battery 12. The OBC11 can simultaneously have both an AC-to-DC module and a DC-to-DC module. The AC-to-DC module converts the AC power output from the power supply circuit 202 into DC power, while the DC-to-DC module converts the DC voltage into the charging voltage for the high-voltage battery 12, thus charging the high-voltage battery 12.

[0059] The OBC11 may also include a power distribution unit (PDU), which can receive power from DC-to-DC converters or AC-to-DC converters. The PDU can distribute and manage the received power.

[0060] In another specific application scenario, the power conversion device is used in electric vehicle charging stations, such as... Figure 1As shown, the charging station 201 mainly includes a power supply circuit 202 and a charging gun 203. The input terminal of the power supply circuit 202 can receive AC power from the power grid 30, and the output terminal of the power supply circuit 202 is connected to the charging gun 203 via a cable. Generally, the power supply circuit 202 can convert the received AC power into charging power compatible with the electric vehicle 10. The charging power converted by the power supply circuit 202 can be input to the OBC11 through the charging gun 203. For example, the power supply circuit 202 can output AC power or DC power through the charging gun 203.

[0061] Currently, the requirements for charging speeds of new energy vehicles are becoming increasingly stringent. To shorten charging time, high-power charging is necessary. In practical applications, DC-to-DC modules or DC-DC conversion circuits are composed of DC converters made up of switching devices. However, the power conversion capability of a single DC converter is limited. Therefore, DC-to-DC modules typically incorporate multiple DC converters, each converting a portion of the power, thereby enhancing the module's power conversion capability and enabling high-power charging of new energy vehicles.

[0062] See Figure 2 The diagram shown is a schematic of a circuit structure for a DC-to-DC converter. Figure 2 As shown, a DC-DC converter module may include N DC-DC converters, with their input terminals connected in series. Specifically, the positive terminal of the input terminal of the first DC-DC converter is connected to the positive terminal of the power supply, and the negative terminal of the input terminal of the last DC-DC converter is connected to the negative terminal of the power supply.

[0063] See Figure 2 As shown, typically one or more electrolytic capacitors are connected in parallel at the input terminal of each DC-DC converter. These electrolytic capacitors form one or more series branches, which divide the input voltage. The input voltage of each DC-DC converter is determined by the voltage received by the parallel electrolytic capacitors. Since the input terminals of N DC-DC converters are connected in series, each converter has the same input current. Therefore, the electrolytic capacitors can control the input voltage of each DC-DC converter, thus distributing the input power to each converter.

[0064] See Figure 2 As shown, due to the large capacity of electrolytic capacitors, when the DC-to-DC converter performs conversion, the large electrolytic capacitors can maintain the stability of the input voltage amplitude of the DC-to-DC converter, and then distribute the power received by the DC-to-DC converter proportionally to each DC converter.

[0065] In actual use, when any one of the N DC-DC converters fails, such as a short circuit, the electrolytic capacitor connected in parallel with the input terminal of the failed DC-DC converter will be short-circuited. At this time, all the input voltage of the DC-DC converter will be distributed to the two ends of the electrolytic capacitors that have not failed. Since the electrolytic capacitors have poor high voltage resistance, these electrolytic capacitors may be damaged due to the high voltage. At this time, the entire DC-DC converter will not work, and the safety of the components cannot be guaranteed.

[0066] In view of this, this application firstly provides a power conversion device that can improve the operational stability of the power conversion device and reduce its operating costs. It should be noted that the power conversion device provided in this application can be applied to electric vehicles; the following description uses the example of powering a high-voltage battery 12 in an electric vehicle. The power conversion device provided in this application can also be applied to other devices, such as devices with multiple loads, such as powering multiple loads in a server or a base station, to improve the availability of the server or base station. This application does not impose excessive limitations on this. The following description uses the application of the power conversion device in an electric vehicle as an example.

[0067] Figure 3 A schematic diagram of a power conversion device provided in this application is shown as an example. This power conversion device 30 can be applied in an electric vehicle. See also... Figure 3 As shown, the power conversion device 30 includes: a first capacitor branch 31, a second capacitor branch 32, and a plurality of DC-DC converters 33.

[0068] The first capacitor branch 31 includes at least one electrolytic capacitor for regulating the voltage received by the power conversion device 30 to obtain a first voltage. The second capacitor branch 32 includes multiple film capacitors connected in series for filtering the first voltage and dividing the filtered first voltage to obtain multiple second voltages, with each film capacitor receiving one second voltage. The DC-DC converter 33 corresponds one-to-one with the film capacitors, and the input terminal of each DC-DC converter 33 is connected in parallel with the corresponding film capacitor. The DC-DC converter 33 can receive the second voltage output by the corresponding film capacitor through its input terminal, perform voltage conversion on the second voltage output by the film capacitor, and output the voltage-converted second voltage through its output terminal.

[0069] In this power conversion device 30, when used to supply power or charge connected devices, the first capacitor branch 31 receives the voltage input from an external power source and regulates the received voltage to obtain a first voltage. Each thin-film capacitor in the second capacitor branch 32 divides the received voltage to obtain a second voltage, and outputs the divided second voltage to the input terminal of the corresponding DC-DC converter 33. The DC-DC converter 33 then performs voltage conversion on the second voltage output from the thin-film capacitor to obtain the charging voltage or supply voltage for the device, thus supplying power or charging the connected device. The DC-DC converter 33 can be a boost converter or a buck converter.

[0070] As an alternative, the power conversion device 30 can be applied to the OBC in an electric vehicle and serve as a DC-to-DC module in the OBC to perform voltage conversion processing on the DC power output from the AC-to-DC module or the charging pile.

[0071] In one example, the outputs of multiple DC-DC converters 33 are all connected to and supply power to the high-voltage battery within the electric vehicle. In this case, the outputs of the multiple DC-DC converters 33 are connected in parallel, thereby enabling high-power charging of the electric vehicle.

[0072] In another example, the outputs of multiple DC-DC converters 33 can be connected in series, with the positive terminal of the output of the first DC-DC converter 33 connected to the positive terminal of the high-voltage battery, and the negative terminal of the output of the last DC-DC converter 33 connected to the negative terminal of the high-voltage battery.

[0073] As an alternative, the power conversion device 30 can be connected between a high-voltage battery and a low-voltage battery, and also between a high-voltage battery and a low-voltage load. In this configuration, the output of at least one DC-DC converter supplies power to the low-voltage load, and the output of at least one DC-DC converter is connected to and charges the low-voltage battery.

[0074] In practical applications, the power conversion device 30 can be fixed to the electric vehicle. Alternatively, the power conversion device 30 can be configured as a flexible, detachable unit, with a fixed interface on the electric vehicle to connect the power conversion device 30 to multiple components within the vehicle. In this case, the power conversion device 30 can be considered a device independent of the electric vehicle.

[0075] See Figure 3As shown, the first capacitor branch 31 is composed of electrolytic capacitors with large capacitance characteristics, and the second capacitor branch 32 is composed of film capacitors with high voltage resistance characteristics. The film capacitors correspond one-to-one with the DC-DC converters and are connected in parallel with the input terminals of the corresponding DC-DC converters to realize the distribution of the input voltage of the corresponding DC-DC converters 33.

[0076] See also Figure 3 As shown, when the power conversion device 30 starts working, the first capacitor branch 31, composed of electrolytic capacitors, stabilizes the voltage received by the power conversion device 30 to obtain a first voltage. The second capacitor branch 32, composed of film capacitors, filters the first voltage. A voltage divider branch composed of multiple film capacitors connected in series divides the filtered first voltage to obtain multiple second voltages. Each film capacitor receives one second voltage and outputs it to the input terminal of the corresponding DC-DC converter 33. The DC-DC converter then performs voltage conversion on the received voltage and supplies power or charges the connected equipment.

[0077] In practical applications, when any DC-DC converter 33 in the power conversion device 30 experiences a short-circuit fault, the film capacitor connected in parallel with the input terminal of the faulty DC-DC converter is short-circuited. This reduces the number of film capacitors connected in series in the second capacitor branch 32. At this time, the film capacitor connected in parallel with the input terminal of the non-faulty DC-DC converter bears the first voltage after all the filter capacitors. Because film capacitors have high voltage resistance, the film capacitor connected in parallel with the input terminal of the non-faulty DC-DC converter can still operate normally under these conditions. The non-faulty DC-DC converter 33 in the power conversion device 30 can still receive voltage and operate, thereby improving the operational stability of the power conversion device 30. Furthermore, if too many DC-DC converters experience short-circuit faults, causing the film capacitors to be damaged due to high voltage, the lower cost of film capacitors compared to electrolytic capacitors can also reduce the operating cost of the power conversion device 30.

[0078] Specifically, when a faulty DC-DC converter occurs in the power conversion device 30, the faulty DC-DC converter stops working, and the second voltage originally received by the faulty DC-DC converter is proportionally distributed to the non-faulty DC-DC converters. Since the voltage received by the non-faulty DC-DC converters increases, while the rated voltage of the equipment connected to the output terminal remains constant, to ensure the normal operation of the equipment connected to the output terminal of the non-faulty DC-DC converters, when a faulty DC-DC converter is identified, the turns ratio of the non-faulty DC-DC converters can be adjusted so that, even with the increased voltage received at the input terminal, the non-faulty DC-DC converters can output the required operating voltage for the connected equipment.

[0079] See Figure 4As shown, the power conversion device 30 may also include a controller, which can be connected to each DC-DC converter 33 in the power conversion device 30 and control the DC-DC converter 33 to perform voltage conversion processing on the voltage received at the input terminal, and adjust the turns ratio of the DC-DC converter 33 when a faulty DC-DC converter occurs in the power conversion device 30.

[0080] The first capacitor branch 31, the second capacitor branch 32, the controller, and the DC-DC converter 34 in the power conversion device 30 will be described in detail below with reference to the embodiments.

[0081] I. First capacitor branch 31

[0082] The two ends of the first capacitor branch 31 are respectively connected to the two ports of the input terminal of the power conversion device 30, and the voltage received at the input terminal of the power conversion device 30 is regulated to obtain the first voltage.

[0083] In one alternative approach, see Figure 5 As shown, the first capacitor branch 31 may include a first electrolytic capacitor C1, which can regulate the voltage received by the power conversion device 30. The first terminal of the first electrolytic capacitor C1 forms the first terminal of the first capacitor branch 31 and is connected to the positive terminal of the external power supply. The second terminal of the first electrolytic capacitor C1 forms the second terminal of the first capacitor branch 31 and is connected to the negative terminal of the external power supply.

[0084] It should be understood that the voltage rating of the first electrolytic capacitor C1 can meet the requirements of the power conversion device 30 for the received voltage amplitude, and the capacitance value of the first electrolytic capacitor C1 can meet the requirements of the power conversion device 30 for the received power.

[0085] In another alternative approach, see Figure 6 As shown, the first capacitor branch 31 may include multiple second electrolytic capacitors C2 connected in series. These multiple second electrolytic capacitors C2 can regulate the voltage received by the power conversion device 30. Specifically, the first terminal of the first second electrolytic capacitor C2 is the first terminal of the first capacitor branch 31 and is connected to the positive terminal of the external power supply. The second terminal of the last second electrolytic capacitor C2 constitutes the second terminal of the first capacitor branch 31 and is connected to the negative terminal of the external power supply.

[0086] In practical use, due to manufacturing issues, the voltage across multiple second electrolytic capacitors connected in series may deviate from their optimal operating voltage range. For example, when the power conversion device 30 receives a voltage of 1000V, if the first capacitor branch 31 includes two second electrolytic capacitors C2, due to individual differences between the two C2 capacitors, one C2 may have a voltage of 520V, while the other may have a voltage of 480V. However, the withstand voltage of an electrolytic capacitor may only be 510V, causing it to be damaged by the high voltage. Therefore, to ensure the safe operation of the second electrolytic capacitors, the power conversion device 30 may also include a device for controlling the voltage across each second electrolytic capacitor.

[0087] In one alternative approach, see Figure 7 As shown, a resistor branch is connected in parallel across the first capacitor branch 31. Multiple first resistors R1 are connected in series in the resistor branch. The first end of the first first resistor R1 is connected to the first end of the first second electrolytic capacitor C2 in the first capacitor branch 31. The second end of the last first resistor R1 is connected to the second end of the last second electrolytic capacitor C2 in the first capacitor branch 31.

[0088] In practical use, the first resistor R1 corresponds to the second electrolytic capacitor C2, and each first resistor R1 is connected in parallel with its corresponding second electrolytic capacitor C2. Multiple first resistors R1 connected in series form a voltage divider branch, which divides the first voltage to obtain multiple third voltages. Each first resistor R1 receives one third voltage. Since the first resistor R1 is connected in parallel with its corresponding second electrolytic capacitor C2, the voltage across the second electrolytic capacitor C2 is the third voltage received by the corresponding first resistor R1. This controls the voltage amplitude across the second electrolytic capacitor C2, ensuring its safe operation.

[0089] It should be understood that when the capacitance values ​​of the multiple second electrolytic capacitors C2 in the first capacitor branch 31 are different, the voltage of each second electrolytic capacitor C2 can be controlled to the required voltage by adjusting the resistance value of the first resistor R1 connected in parallel with the second electrolytic capacitor C2.

[0090] In another alternative approach, see Figure 8 As shown, a voltage equalization circuit is provided at both ends of the first capacitor branch 31. The voltage equalization circuit is used to equalize the voltage across each second electrolytic capacitor C2 in the first capacitor branch 31.

[0091] II. Second capacitor branch 32

[0092] The first terminal of the second capacitor branch 32 is connected to the first terminal of the first capacitor branch 31, and the second terminal of the second capacitor branch 32 is connected to the second terminal of the first capacitor branch 31. The second capacitor branch 32 includes multiple film capacitors C3 connected in series. These multiple film capacitors C3 filter the first voltage output from the first capacitor branch 31. Simultaneously, the multiple film capacitors C3 form a voltage divider branch, dividing the filtered first voltage to obtain multiple second voltages. Each film capacitor C3 receives one second voltage.

[0093] See Figure 9 As shown, the second capacitor branch 32 includes multiple thin-film capacitors C3 connected in series, and the thin-film capacitors C3 correspond one-to-one with the DC-DC converter 33 in the power conversion device 30.

[0094] Specifically, the first terminal of the first film capacitor C3 among the plurality of film capacitors C3 is connected to the first terminal of the first capacitor branch 31, the second terminal of the last film capacitor C3 among the plurality of film capacitors C3 is connected to the second terminal of the first capacitor branch 31, and each film capacitor C3 is connected in parallel with the input terminal of the corresponding DC-DC converter 33.

[0095] In this circuit, multiple thin-film capacitors C3 are connected in series to form a voltage divider branch. Each thin-film capacitor C3 receives a second voltage. Since the thin-film capacitor C3 is connected in parallel with the input terminal of the corresponding DC-DC converter, the voltage received by the DC-DC converter corresponding to the thin-film capacitor C3 is the second voltage, thereby realizing the power distribution to the DC-DC converter 33 corresponding to the thin-film capacitor C3.

[0096] See also Figure 9 As shown, since the input terminals of the DC-DC converter 33 corresponding to the film capacitor C3 are connected in parallel, and multiple film capacitors C3 are connected in series, the input terminals of multiple DC-DC converters 33 are connected in series. Therefore, the current received by the input terminal of each DC-DC converter 33 is the same, and the received power of each DC-DC converter 33 is determined by the voltage received by the DC-DC converter 33. The voltage received by the DC-DC converter 33 is determined by the second voltage obtained by the corresponding film capacitor C3. Therefore, the power received by the DC-DC converter can be adjusted by adjusting the parameters of the film capacitors corresponding to the DC-DC converter 33 in the second capacitor branch 32.

[0097] See also Figure 9As shown, multiple film capacitors C3 are connected in series. When a DC-DC converter malfunctions in the power conversion device 30, the film capacitor C3 corresponding to that DC-DC converter 33 is bypassed. At this time, the number of film capacitors C3 connected in series in the second capacitor branch 32 decreases, while the amplitude of the filtered first voltage remains unchanged. Therefore, the voltage across each of the multiple film capacitors C3 connected in series increases. For example, if the amplitude of the filtered first voltage is 100V, and there are 5 film capacitors C3 connected in series in the first capacitor branch 31, each film capacitor receives a voltage of 20V. When one film capacitor C3 is bypassed, there are 4 film capacitors C3 connected in series in the first capacitor branch 31, and the voltage across each film capacitor C3 is 25V. Because film capacitors C3 have high voltage resistance, they can still operate normally under these conditions, thus ensuring that the DC-DC converters 33 corresponding to these film capacitors can operate normally and improving the operational stability of the power conversion device 30.

[0098] See also Figure 9 As shown, when a large number of DC converters in the power conversion device 30 fail, causing the voltage across the film capacitors of the non-faulty DC converters to exceed their maximum withstand voltage, the operating cost of the power conversion device 30 can be reduced because the cost of the film capacitor C3 is lower than that of the electrolytic capacitor.

[0099] III. DC-DC converter 33

[0100] The input terminals of multiple DC-DC converters 33 are connected in series. The first input terminal of the first DC-DC converter 33 is connected to the first terminal of the first capacitor branch 31 and the first terminal of the second capacitor branch 32. The second input terminal of the last DC-DC converter 33 is connected to the second terminal of the first capacitor branch 31 and the second terminal of the second capacitor branch 32.

[0101] In this embodiment, the DC-DC converter 33 can adopt an existing structure, namely, an H-bridge rectifier circuit. The first end of the first arm and the first end of the second arm of the H-bridge rectifier circuit constitute the first input terminal of the DC-DC converter 33. The second end of the first arm and the second end of the second arm of the H-bridge rectifier circuit constitute the second input terminal of the DC-DC converter 33. The middle node of the first arm of the H-bridge rectifier circuit constitutes the first output terminal of the DC-DC converter 33, and the middle node of the second arm of the H-bridge rectifier circuit constitutes the second output terminal of the DC-DC converter 33. The DC-DC converter 33 can be connected to the two ends of the corresponding thin-film capacitor through the first and second input terminals and receive the second voltage output by the corresponding thin-film capacitor. The DC-DC converter 33 outputs the voltage-converted electrical energy to the connected device through the first and second output terminals.

[0102] Using the DC-DC converter 33 described above, the electrical energy output from the corresponding thin-film capacitor can be regulated, and the DC-DC converter 33 can output the power supply voltage required by the connected equipment.

[0103] For example, the structure of the DC-DC converter 33 can be as follows: Figure 10 .exist Figure 10 In the circuit, A serves as the first input terminal of DC-DC converter 33, B serves as the second input terminal of DC-DC converter 33, C serves as the first output terminal of DC-DC converter 33, and D serves as the second output terminal of DC-DC converter 33. MOSFETs Q1 / Q2 / Q3 / Q4 form an H-bridge rectifier circuit.

[0104] When the power conversion device 30 supplies power or charges the device connected to the output terminal, A and B serve as input terminals to receive the second voltage output by the corresponding thin film capacitor, and C and D serve as output terminals to output the voltage after being regulated by MOSFETs Q1 / Q2 / Q3 / Q4, and to supply power or charge the connected device.

[0105] See also Figure 10 As shown, when a short-circuit fault occurs in DC-DC converter 33, the film capacitor C3 connected in parallel with the input terminal of DC-DC converter 33 will be short-circuited. At this time, the faulty DC-DC converter will be bypassed from the series branch of DC-DC converter 33, thus ensuring that the non-faulty DC-DC converter can work normally. When DC-DC converter 33 experiences other types of faults, the faulty DC-DC converter can also be bypassed from the series-connected DC-DC converters by controlling the conduction of MOSFETs Q1 and Q2, thus ensuring that the non-faulty DC-DC converter can work normally.

[0106] In one alternative approach, see Figure 11 As shown, the power conversion device 30 is applied in an electric vehicle and serves as a DC-to-DC module for the on-board unit (OBC) in the electric vehicle. At this time, the output terminals of all DC-DC converters 33 in the power conversion device 30 are connected in parallel and connected to the high-voltage battery to charge the high-voltage battery.

[0107] In another alternative approach, see Figure 12 As shown, the power conversion device 30 is used in an electric vehicle and serves as a DC-to-DC module for the on-board battery (OBC). If the output voltage of a single DC converter 33 is lower than the charging voltage of the high-voltage battery, the output terminals of multiple DC converters 33 can be connected in series to increase the output voltage amplitude and meet the charging voltage requirements of the high-voltage battery. In this case, the first output terminal of the first DC converter among the multiple DC converters 33 is connected to the positive terminal of the high-voltage battery, and the second output terminal of the last DC converter among the multiple DC converters 33 is connected to the negative terminal of the high-voltage battery.

[0108] In another alternative embodiment, the power conversion device 30 is applied within an electric vehicle and connected between the high-voltage battery and the low-voltage battery, as well as between the high-voltage battery and the low-voltage load. The power conversion device converts the voltage input from the high-voltage battery into the charging voltage for the low-voltage battery and the supply voltage for the low-voltage load. In this case, multiple DC-DC converters 33 are connected to different devices. For example, the output of the first DC-DC converter is connected to the low-voltage battery, the output of the second DC-DC converter is connected to the first low-voltage load, and so on, to power or charge all devices.

[0109] It should be understood that the above description of DC-DC converters is only an example. In actual use, DC-DC converters can also adopt other circuit structures, such as half-bridge rectifier circuits, inductor-inductor-capacitor (LLC) resonant converter circuits, forward converters, flyback converters, adjustable boost converters, adjustable buck converters, or buck-boost converters.

[0110] IV. Controller

[0111] The controller is connected to each DC-DC converter 33 in the power conversion device 30 and controls each DC-DC converter 33 to perform voltage conversion processing on the voltage received at the input terminal, and adjusts the turns ratio of the non-faulty DC-DC converters when a faulty DC-DC converter occurs in the power conversion device 30.

[0112] In a practical implementation, the DC-DC converter 33 can be composed of devices such as switching transistors, diodes, inductors, and capacitors. The operating state and turns ratio of the DC-DC converter can be adjusted by regulating the operating state of these devices (e.g., the switching transistors).

[0113] Specifically, if the switching transistor in the DC-DC converter 33 is a MOSFET, the controller can be connected to the gate of the MOSFET, thereby controlling the switching of the MOSFET to enable the DC-DC converter to regulate the voltage received at the input terminal and to supply power or charge the connected device; if the switching transistor in the DC-DC converter 33 is a BJT, the controller can be connected to the base of the BJT, thereby controlling the switching of the BJT to enable the DC-DC converter to regulate the voltage received at the input terminal and to supply power or charge the connected device.

[0114] In one alternative embodiment, the power conversion device 30 further includes a detection device that can be connected to the DC-DC converter in the power conversion device 30 and detect the operating status of the DC-DC converter. When it is determined that the DC-DC converter has failed, the detection device sends a first signal indicating the failure of the DC-DC converter to the controller. When the controller receives the first signal, it adjusts the drive signal of the switching transistor in the DC-DC converter that has not failed, so as to adjust the turns ratio of the DC-DC converter that has not failed, thereby enabling the DC-DC converter to output a supply voltage or charging voltage that meets the voltage requirements of the connected equipment.

[0115] Optionally, the detection device can determine the operating state of the DC-DC converter by detecting its output current and output voltage.

[0116] In another alternative approach, the controller in the power conversion device 30 is also connected to an external detection device, and upon receiving a second signal indicating a DC-DC converter fault sent by the external detection device, adjusts the drive signal output to the switching transistor in the non-faulty DC-DC converter to adjust the turns ratio of the non-faulty DC-DC converter and make the DC-DC converter output a supply voltage that meets the voltage requirements of the connected equipment.

[0117] In practice, the controller can be any of the following: a microcontroller unit (MCU), a central processing unit (CPU), or a digital signal processor (DSP). Of course, the specific form of the controller is not limited to the examples mentioned above.

[0118] It should be understood that the aforementioned controller can only maintain the operation of the power conversion device 30 when a single or a few DC-DC converters fail. When too many DC-DC converters fail within the power conversion device 30, other components within the power conversion device fail, or equipment connected to the power conversion device fails, the operation of the power conversion device cannot be guaranteed. Therefore, the power conversion device may also include a protector. This protector can be connected to the first terminal of the first capacitor branch 31 and the second capacitor branch 32, and detects the voltage or current received by the power conversion device. When a failure in the equipment connected to the power conversion device or a failure in a component within the power conversion device causes the voltage or current on the line to exceed a set threshold, the protector disconnects the power conversion device from the external power supply, thereby protecting the power conversion device and the components connected to it. See also... Figure 13 As shown, the protector can be a fuse, but it can also be other protective devices, such as circuit breakers or other devices that have overvoltage or overcurrent protection.

[0119] Based on the same inventive concept, this application also provides a charging pile, which may include a first conversion circuit and the aforementioned power conversion device 30.

[0120] The first conversion circuit is connected to an external power source and converts the AC power output from the external power source into DC power, which is then output to the power conversion device. The power conversion device is connected to the first conversion circuit and performs voltage conversion on the DC power output from the first conversion circuit, using the converted voltage to power the load.

[0121] In practice, the external power source can be the power grid, the first conversion circuit can convert the AC power on the power grid into DC power, and the power conversion device can convert the DC power output by the first conversion circuit into the vehicle's charging voltage, thereby enabling the vehicle to be charged.

[0122] Based on the same inventive concept, this application also provides a vehicle charger, which includes a first conversion circuit and the aforementioned power conversion device 30.

[0123] The first conversion circuit is connected to an external power source and converts the AC power output from the external power source into DC power, which is then output to the power conversion device. The power conversion device is connected to the first conversion circuit and performs voltage conversion on the DC power output from the first conversion circuit, using the converted voltage to power the load.

[0124] In practice, the first conversion circuit in the vehicle charger can convert the AC power obtained from the charging pile into DC power, and the power conversion device can convert the DC power output by the first conversion circuit into the charging voltage of the high-voltage battery and charge the high-voltage battery.

[0125] It should be understood that if the charging pile obtains DC power, the on-board charger in this application may only include a power conversion device, which can directly convert the DC power obtained from the charging pile into the charging voltage of the high-voltage battery and charge the high-voltage battery.

[0126] Based on the same inventive concept, this application also provides an electric vehicle, which may include a high-voltage battery, a low-voltage battery, a low-voltage load and the aforementioned power conversion device 30.

[0127] The high-voltage battery is connected to the power conversion device and is used to output the stored electrical energy to the power conversion device.

[0128] The power conversion device is connected to the low-voltage battery and the low-voltage load respectively. It is used to perform voltage conversion on the electrical energy output from the high-voltage battery and to supply power to the low-voltage battery and the low-voltage load with the converted electrical energy.

[0129] It should be understood that the solutions provided in this application can be applied to different types of vehicles, specifically including but not limited to pure electric vehicles (Pure EVs / Battery EVs) and hybrid electric vehicles (HEVs). Furthermore, the devices provided in this application are not limited to the automotive field, but can also be applied to fields such as wind power generation and photovoltaic power generation. For example, they can be applied to energy storage systems within wind power generation systems or photovoltaic power generation systems to charge the batteries within the energy storage systems.

[0130] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the scope of protection of this application. Therefore, if such modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include such modifications and variations.

Claims

1. A power conversion device, characterized in that, include: The first capacitor branch includes at least one electrolytic capacitor for stabilizing the voltage received by the power conversion device to obtain a first voltage. The second capacitor branch includes multiple film capacitors connected in series, used to filter the first voltage and to divide the filtered first voltage to obtain multiple second voltages; wherein each film capacitor receives one second voltage. A DC-DC converter that corresponds one-to-one with each of the thin-film capacitors, with the input terminal of each DC-DC converter connected in parallel with the corresponding thin-film capacitor; The DC-DC converter is used to perform voltage conversion processing on the second voltage output by the thin-film capacitor.

2. The power conversion device according to claim 1, characterized in that, The first capacitor branch includes a first electrolytic capacitor, which is used to stabilize the voltage received by the power conversion device to obtain the first voltage.

3. The power conversion device according to claim 1, characterized in that, The first capacitor branch includes a plurality of second electrolytic capacitors connected in series. The plurality of second electrolytic capacitors connected in series are used to stabilize the voltage received by the power conversion device to obtain the first voltage.

4. The power conversion device according to claim 3, characterized in that, The power conversion device further includes a resistor branch connected in parallel with the first capacitor branch. The resistor branch includes a plurality of first resistors, each first resistor corresponding to each second electrolytic capacitor, and each first resistor connected in parallel with the corresponding second electrolytic capacitor.

5. The power conversion device according to claim 3, characterized in that, The power conversion device further includes: a voltage equalization circuit; The voltage equalization circuit is connected to the first capacitor branch and performs voltage stabilization on each second electrolytic capacitor.

6. The power conversion device according to any one of claims 1-5, characterized in that, The outputs of the multiple DC-DC converters are connected in parallel.

7. The power conversion device according to any one of claims 1-6, characterized in that, The outputs of the multiple DC-DC converters are connected in series.

8. The power conversion device according to any one of claims 1-7, characterized in that, The power conversion device further includes: a protector; The protector is used to disconnect the power conversion device from the external power source when the voltage or current received by the power conversion device exceeds a preset threshold.

9. The power conversion device according to any one of claims 1-8, characterized in that, The power conversion device further includes: a controller; The controller is connected to the plurality of DC converters, and the controller is used to adjust the voltage conversion ratio of the non-faulty DC converters when it is determined that any DC converter among the plurality of DC converters has failed.

10. A charging pile, characterized in that, The charging pile includes: a first conversion circuit and a power conversion device as described in any one of claims 1-9; The first conversion circuit is used to connect to an external power source and convert the AC power output by the external power source into DC power. The power conversion device is connected to the first conversion circuit and is used to perform voltage conversion processing on the DC power output by the first conversion circuit, and to use the DC power after voltage conversion to power the connected equipment.

11. A vehicle charger, characterized in that, The vehicle charger includes: a first conversion circuit and a power conversion device as described in any one of claims 1-9; The first conversion circuit is used to receive the AC power output from the charging pile and convert the AC power output from the charging pile into DC power. The power conversion device is connected to the first conversion circuit and is used to perform voltage conversion processing on the DC power output by the first conversion circuit, and to use the DC power after voltage conversion to charge the high-voltage battery of the electric vehicle.

12. An electric vehicle, characterized in that, The electric vehicle includes: a high-voltage battery, a low-voltage battery, a low-voltage load, and a power conversion device as described in any one of claims 1-9; The high-voltage battery is connected to the power conversion device; The power conversion device is connected to the low-voltage battery and the low-voltage load respectively. The power conversion device is used to perform voltage conversion processing on the electrical energy output by the high-voltage battery, and to supply power to the low-voltage battery and the low-voltage load with the voltage-converted electrical energy.

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