Power conversion device and uninterruptible power supply

Abstract

A power conversion device and an uninterruptible power supply are used for reducing the cost of the power conversion device and reducing the size of the power conversion device. The power conversion device comprises a conversion circuit, a bus capacitor branch, a resistor module, a first switch module and a controller. The input end of the conversion circuit is connected with the power supply, and the output end is connected with the bus capacitor branch through the resistor module; the first switch module is connected in parallel with the resistor module; the controller is connected with the first switch module, controls the first switch module to be switched off when the conversion circuit is connected with the power supply and the voltage of the bus capacitor branch is smaller than a preset threshold value, and controls the first switch module to be switched on when the voltage of the bus capacitor branch is larger than or equal to the preset threshold value. When the bus capacitor needs to be pre-charged, the first switch module can be controlled to be switched off, and the resistor module serves as a current-limiting resistor to charge the bus capacitor branch. And after the bus capacitor branch is charged, the first switch module is controlled to be closed, so that the loss generated by the resistor module during normal power supply is eliminated.

Description

Technical Field

[0001] The present application relates to the field of power electronics technology, and in particular to a power conversion device and an uninterruptible power supply. Background Art

[0002] With the continuous development of the Internet and financial industries, the safe and reliable operation of equipment has become increasingly important. As a key power supply device, the uninterruptible power system (UPS) plays an important role.

[0003] A UPS is equipped with multiple components, including a rectifier, a battery pack, and a battery charger / discharger. The rectifier converts the voltage of the external AC power source into the load's supply voltage and provides power to the load. The battery charger / discharger also converts the stored energy in the battery pack into the load's supply voltage and provides power to the load in the event of an AC power failure. In actual use, the output side of the rectifier is equipped with bus capacitors to stabilize the output voltage, which are connected to the load. Before the UPS is started, there is no voltage on the bus capacitors. If the UPS is directly connected to the AC power source or the bus capacitors are connected to the battery pack via a battery charger / discharger, a surge current will be generated in the line, which can damage components. Currently, the industry generally uses a dedicated pre-charge circuit that charges the bus capacitors to a set value to reduce the voltage difference between the bus capacitors and the power source, thereby protecting the UPS. However, the addition of a pre-charge circuit increases the space and cost of the UPS and increases the design difficulty of the UPS. Utility Model Content

[0004] The present application provides a power conversion device and an uninterruptible power supply, which are used to reduce the cost and area of ​​the power conversion device.

[0005] In a first aspect, embodiments of the present application provide a power conversion device that can be used in high-power power supply systems where bus capacitors are provided at the output of a conversion circuit within the power supply system. The power conversion device includes a conversion circuit, a bus capacitor branch, a resistor module, a first switch module, and a controller.

[0006] In which, the input end of the conversion circuit is used to connect to the power supply, and the output end of the conversion circuit is connected to the bus capacitor branch through the resistance module; the first switch module is connected in parallel with the resistance module; the controller is connected to the first switch module, and is used to control the first switch module to disconnect when the conversion circuit is connected to the power supply and the voltage of the bus capacitor branch is less than a preset threshold, and to control the first switch module to close when the voltage of the bus capacitor branch is greater than or equal to the preset threshold.

[0007] With the above design, when the power conversion device is connected to the power supply and the bus capacitor branch voltage is low, in order to avoid damage to the device due to the large voltage difference between the power supply voltage and the bus capacitor branch, the controller can control the first switch module to disconnect. At this time, the resistor module is connected to the charging circuit of the bus capacitor branch and acts as a current-limiting resistor in the charging circuit to reduce the current amplitude in the charging circuit, thereby ensuring the safety of the device while pre-charging the bus capacitor branch. After the bus capacitor branch is charged, the first switch module can be controlled to short-circuit the resistor module, thereby eliminating the loss generated by the resistor module during normal operation. With the above design, only the switch module and the resistor module need to be added to realize pre-charging of the bus capacitor, reducing the cost of the power conversion device and reducing the size of the power conversion device.

[0008] In one possible design, depending on the application scenario of the power conversion device, the bus capacitor branch in the power conversion device may include one bus capacitor or two bus capacitors. In order to complete the pre-charging function of each bus capacitor, the resistance module includes a first resistor corresponding to each bus capacitor in the bus capacitor branch, and the first resistor is connected in series with the corresponding bus capacitor.

[0009] In one possible design, the resistor in the resistor module is a thermistor. With this design, as the charging time of the bus capacitor branch increases, the voltage across the bus capacitor branch also increases, meaning the voltage difference between the power supply voltage and the bus capacitor branch also decreases. To reduce losses during the pre-charging process, a thermistor whose resistance decreases with increasing temperature can be used to improve pre-charging efficiency.

[0010] In one possible design, when the bus capacitor branch includes multiple bus capacitors, a resistor device connected in series with each bus capacitor will be configured in the resistor module. In order to control the connection relationship of the above-mentioned resistor devices, the first switch module includes a first switch corresponding to each first resistor one by one, each first switch is connected in parallel with the corresponding first resistor, and the control end of each first switch is connected to the controller.

[0011] In one possible design, when the above-mentioned power conversion device is applied to a high-power power supply scenario, for example, when the power conversion device is applied to an uninterruptible power supply or a photovoltaic power generation system, the power conversion device also includes: a battery pack and a battery charge and discharge circuit; the battery pack is connected to the first end of the battery charge and discharge circuit; the second end of the battery charge and discharge circuit is connected to the output end of the conversion circuit.

[0012] In one possible design, the controller is further configured to control the first switch module to open when the battery pack is electrically connected to the bus capacitor branch via the battery charge and discharge circuit and the voltage of the bus capacitor branch is less than a preset threshold, and to control the first switch branch to close when the voltage of the bus capacitor branch is greater than or equal to the preset threshold. With the above design, when a battery pack is configured in the power conversion device, the power conversion device can use the electrical energy stored in the battery pack to pre-charge the bus capacitor branch.

[0013] In one possible design, the power conversion device further includes a second switch module connected between the input end of the conversion circuit and the power supply, and the second switch module is used to control the connection between the conversion circuit and the power supply.

[0014] In one possible design, the power conversion device further includes a third switch module connected between the battery pack and the charge and discharge circuit, and the third switch module is used to control the connection between the battery pack and the charge and discharge circuit.

[0015] In one possible design, the power conversion device also includes a voltage sensor, which is connected to the bus capacitor branch and the controller. The voltage sensor is used to detect the voltage of the bus capacitor branch and output the detected voltage to the controller.

[0016] In a second aspect, an embodiment of the present application provides an uninterruptible power supply, which includes an inverter and a power conversion device provided in the first aspect of the embodiment of the present application and any possible design thereof.

[0017] The input end of the inverter is connected to the output end of the conversion circuit, and the output end of the inverter is connected to the load. The inverter can convert the voltage output by the conversion circuit into the supply voltage of the load and supply power to the load.

[0018] In addition, the technical effects brought about by the second aspect and any possible design thereof can be referred to the technical effects brought about by the different designs in the first aspect of the embodiment of the present application, and will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0020] Figure 1 A schematic diagram of the structure of a power conversion device provided in an embodiment of the present application Figure 1 ;

[0021] Figure 2 A schematic structural diagram of a power conversion device provided in Example 1 of the present application;

[0022] Figure 3 A schematic structural diagram of a conversion circuit provided in Example 1 of the present application;

[0023] Figure 4 A schematic diagram of the structure of a first switch module provided in Example 1 of the present application Figure 1 ;

[0024] Figure 5 A schematic diagram of the structure of a first switch module provided in an embodiment of the present application Figure 2 ;

[0025] Figure 6 A schematic structural diagram of a power conversion device provided in Example 2 of the present application;

[0026] Figure 7 A schematic structural diagram of a conversion circuit provided in Example 2 of the present application;

[0027] Figure 8 A schematic diagram of the structure of a power conversion device provided in an embodiment of the present application Figure 3 ;

[0028] Figure 9 A schematic diagram of the structure of a power conversion device provided in an embodiment of the present application Figure 4 ;

[0029] Figure 10 A schematic diagram of the structure of a power conversion device provided in an embodiment of the present application Figure 5 . DETAILED DESCRIPTION

[0030] The following will introduce the application scenarios of the technical solutions in the embodiments of the present application in conjunction with the drawings in the embodiments of the present application. The solution provided in the embodiments of the present application can be applied to a high-power power supply system, and the rectifier in the power supply system is configured with a bus capacitor for filtering and stabilizing the output voltage. Among them, the above-mentioned power distribution system can be but is not limited to: an uninterruptible power supply (UPS), a photovoltaic power generation system and an on-board charger.

[0031] In actual applications, the output end of the power conversion device is equipped with a bus capacitor for filtering and stabilizing the output voltage. When the power supply system is initially started or restored after maintenance, there is no voltage on the bus capacitor, resulting in a large difference between the bus capacitor voltage and the external power supply voltage when the power supply system is connected to the power supply. If directly connected, it may generate a surge current on the line, causing damage to the internal components of the power conversion device and the components connected to the power conversion device. At present, the industry mostly adopts an additional pre-charging circuit to pre-charge the voltage of the bus capacitor to a set value, and then control the power conversion device to be connected to the power supply, thereby ensuring the normal operation of the power conversion device. However, the additional pre-charging circuit increases the cost of the power conversion device, and the pre-charging circuit also increases the volume of the power conversion device, increasing the design difficulty of the power conversion device.

[0032] Based on this, embodiments of the present application provide a power conversion device and an uninterruptible power supply, which are used to reduce the cost and size of the power conversion device.

[0033] The power conversion device provided in the embodiment of the present application can be applied to a high-power power supply system and connected as an external power supply of the power supply system, and is used to convert the voltage of the external power supply into a DC voltage of a fixed amplitude, and use the DC voltage to directly power the load or provide it to other devices in the power supply system. Figure 1 As shown in FIG, a schematic diagram of the structure of a power conversion device provided in an embodiment of the present application is shown. Figure 1 As shown, the power conversion device includes a conversion circuit, a bus capacitor branch, a resistor module, a first switch module and a controller.

[0034] Specifically, the input end of the conversion circuit is used to connect to the power supply, and the output end of the conversion circuit is connected to the bus capacitor branch through the resistor module; the first switch module is connected in parallel with the resistor module; the controller is connected to the first switch module, and is used to control the first switch module to disconnect when the conversion circuit is connected to the power supply and the voltage of the bus capacitor branch is less than a preset threshold, and to control the first switch module to close when the voltage of the bus capacitor branch is greater than or equal to the preset threshold. Among them, the preset threshold can be set according to the power supply voltage and the model of each component inside the power conversion device. For example, the preset threshold can be set to 80% of the power supply voltage. Of course, the preset threshold can also be set to other values, and this application does not make too many restrictions here.

[0035] It should be noted that, depending on the application scenario of the power supply system to which the power conversion device belongs, the power supply can be a DC power supply or an AC power supply. For example, when the power supply system is a UPS or a car charger, the power supply can be an AC grid. When the power supply system is a luminous power generation system, the power supply can be a photovoltaic panel for outputting DC power.

[0036] In practical applications, the power conversion device can be considered a device independent of other devices in the power supply system. The power conversion device can be configured to be flexibly detachable from other devices in the power supply system. For example, the power conversion device can be provided with a fixed external interface, and other devices in the power supply system can be connected to the power conversion device through the external interface. The power conversion device can also be packaged with other devices in the power supply system as an integrated device.

[0037] use Figure 1 When the power conversion device shown is pre-charging the bus capacitor in the bus capacitor branch, since the conversion circuit is connected to the bus capacitor branch through the resistor module, and a first switch module is connected in parallel at both ends of the resistor module, when the controller detects that the bus capacitor voltage in the bus capacitor branch is less than a preset threshold, in order to avoid generating an inrush current on the power conversion device circuit, the first switch module connected in parallel with the resistor module can be controlled to be disconnected. At this time, the resistor module is connected to the bus capacitor branch. The resistor module acts as a current limiting resistor to reduce the current amplitude on the circuit when the conversion circuit is working and charge the bus capacitor in the bus capacitor branch. As the charging time increases, the voltage across the bus capacitor in the bus capacitor branch increases. When the controller detects that the voltage across the bus capacitor is charged to a preset threshold, it can control the first switch module connected in parallel with the resistor module to be closed. At this time, the resistor module is cut off from the main circuit of the power conversion device, and the power conversion device operates normally and starts power supply. By pre-charging the bus capacitor in the above manner, it is only necessary to add a first switch module and a resistor module to the power conversion device architecture to achieve pre-charging power. Compared with the industry's separate configuration of a pre-charging circuit, the device cost of the power conversion device is reduced, and the volume of the power conversion device is reduced.

[0038] In actual application, depending on the application scenario of the power conversion device, the bus capacitor branch includes one or more bus capacitors. In order to achieve normal pre-charging of the above-mentioned bus capacitors, the resistor module includes a first resistor corresponding to each bus capacitor in the bus capacitor branch. The first resistor is connected in series with the corresponding bus capacitor and serves as a current limiting resistor during the pre-charging process of the corresponding bus capacitor. In order to control the end time of bus capacitor pre-charging, the first switch module also needs to be configured with a first switch corresponding to each first resistor. Each first switch is connected in parallel with the corresponding first resistor, and the control end of each first switch is connected to the controller.

[0039] In combination with the above description, depending on the number of bus capacitors in the bus capacitor branch, the power conversion device provided in the embodiment of the present application can have different topologies. Below, in combination with the embodiment, the cases where the bus capacitor branch includes one bus capacitor and two bus capacitors are introduced respectively.

[0040] See also Figure 2As shown in FIG, it is a schematic diagram of the structure of the power conversion device provided in Example 1 of the present application. Figure 2 As shown, the bus capacitor branch includes a bus capacitor C1, the resistor module includes a first resistor R1 corresponding to the bus capacitor C1, and the first switch module includes a first switch K1 corresponding to the first resistor R1.

[0041] Continue to see Figure 2 As shown, the bus capacitor C1 is connected to the conversion circuit through the first resistor R1. The conversion circuit can obtain electrical energy from an external power supply and convert it into a charging voltage for the bus capacitor C1.

[0042] In one example, if the power source connected to the conversion circuit is an AC power source, the conversion circuit can use a single-phase rectifier or a three-phase rectifier. The above rectifier can use a bridge rectifier structure, and of course other circuits with the above rectification function can also be used in the industry.

[0043] Specifically, taking the conversion circuit as a three-phase bridge rectifier topology as an example, the structure of the power conversion device is as follows: Figure 3 See Figure 3 As shown, switches Q1 to Q6 and inductors L1 to L3 form a conversion circuit. When the power conversion device is connected to a three-phase AC power source, the parasitic diodes of switches Q1 to Q6 perform uncontrolled rectification on the three-phase AC power source to generate a DC voltage. This DC voltage can then be current-limited by first resistor R1 and then used to charge bus capacitor C1.

[0044] In one example, if the power source connected to the conversion circuit is a DC power source, for example, if the power conversion device is used in a photovoltaic power generation system, the conversion circuit can be connected to the photovoltaic panel and step up the DC voltage output by the photovoltaic panel so that the inverter connected to the back end can perform inversion and grid connection processing. The conversion circuit can adopt a DC / DC direct current conversion structure, and of course other topologies can also be used, which is not limited in this application.

[0045] use Figure 2 or Figure 3 When the power conversion device shown is pre-charging the bus capacitor C1, when the power conversion device is connected to an external power supply through the conversion circuit, the conversion circuit can convert the voltage of the external power supply into a DC voltage and charge the bus capacitor C1 through the first resistor R1 with a current limiting function. The charging time of the bus capacitor C1 can be configured by the resistance value of the first resistor R1 and the capacitance value of the bus capacitor C1, which will not be described in detail in this application.

[0046] In a possible implementation, the first switch K1 is a switch tube, which may be, but is not limited to, a metal oxide semiconductor field effect transistor (MOSFET) and an insulated gate bipolar transistor (IGBT). The controller may be connected to the control terminal of the first switch K1. Taking the first switch K1 as a MOSFET as an example, the structure of the power conversion device is as follows: Figure 4 shown.

[0047] In one possible implementation, the first switch K1 is a contact of a relay KM1. The coil of the relay KM1 is connected to the bus capacitor C1 via a second switch K2. The second switch K2 can be a switching tube, and the control end of the second switch K2 is connected to the controller. The controller can control the power supply and de-power supply of the coil of the relay KM1 by controlling the conduction and shutdown of the second switch K2, thereby controlling the closing or opening of the first switch K1. The structure of the power conversion device can be seen in FIG. Figure 5 shown.

[0048] In one example, if the controller and the coil of the relay KM1 are powered by a bus capacitor, in order to avoid the inability to control the switch state due to the lack of electrical energy stored in the bus capacitor C1, the first switch K1 can use the normally open contact of the relay KM1. When the controller cannot obtain electrical energy and causes the second switch K2 to be turned off, the first switch K1 is disconnected and the first resistor R1 pre-charges the bus capacitor C1.

[0049] In one example, if the controller and the coil of the relay KM1 are connected to an external DC power supply, the first switch K1 may be a normally open contact of the relay KM1 or a normally closed contact of the relay KM1.

[0050] See also Figure 6 As shown in FIG, it is a schematic diagram of the structure of the power conversion device provided in the second embodiment of the present application. Figure 6 As shown, the bus capacitor branch includes a bus capacitor C1 and a bus capacitor C2, the resistor module includes a first resistor R1 corresponding to the bus capacitor C1 and a first resistor R2 corresponding to the bus capacitor C2, and the first switch module includes a first switch K1 corresponding to the first resistor R1 and a first switch K2 corresponding to the first resistor R2.

[0051] Continue to see Figure 6 As shown, the bus capacitor C1 is connected to the conversion circuit through the resistor R1, and the bus capacitor C2 is connected to the conversion circuit through the resistor R2. The conversion circuit can obtain electrical energy from the external power supply and convert it into a charging voltage for the bus capacitor C1 and the bus capacitor C2.

[0052] In one example, if the power source connected to the conversion circuit is an AC power source, the conversion circuit can use a single-phase rectifier or a three-phase rectifier. The above rectifier can use a bridge rectifier structure, and of course other circuits with the above rectification function can also be used in the industry.

[0053] Specifically, taking the conversion circuit as a three-phase Vienna rectifier topology as an example, the structure of the power conversion device is as follows: Figure 7 See Figure 7 As shown, switches Q1 to Q6, diodes D1 to D6, and inductors L1 to L3 form a conversion circuit. When the power conversion device is connected to a three-phase AC power source, diodes D1 to D6 perform uncontrolled rectification on the three-phase AC power source to generate a DC voltage. This DC voltage can then be current-limited by resistors R1 and R2 to charge bus capacitors C1 and C2.

[0054] In one example, if the power source connected to the conversion circuit is a DC power source, the conversion circuit may adopt a DC / DC direct current conversion structure. Of course, other topologies may also be selected, and this application does not make too many restrictions here.

[0055] use Figure 6 or Figure 7 When the power conversion device shown is pre-charging the bus capacitor C1 and the bus capacitor C2, when the power conversion device is connected to the external power supply through the conversion circuit, the control device controls the first switch K1 and the second switch K2 to be turned off. At this time, the conversion circuit can convert the voltage of the external power supply into a DC voltage, and the above DC voltage is used to charge the bus capacitor C1 and the bus capacitor C2 through a series circuit composed of a resistor R1, a bus capacitor C1, a bus capacitor C2 and a resistor R2. Among them, the charging time of the bus capacitor C1 and the bus capacitor C2 can be configured by the resistance value of the resistor R1, the resistance value of the resistor R2 and the capacitance value of the two bus capacitors, which will not be described in detail in this application.

[0056] It should be noted that the switch selection of the first switch K1 and the first switch K2 can be referred to the relevant introduction of the first embodiment of the present application, and will not be repeated here in this application.

[0057] See also Figures 2 to 7 In the power conversion device shown, the controller in the power conversion device controls the switching devices in the first switch module through the bus capacitor voltage. In actual application, the controller can be connected to a voltage sensor outside the power conversion device and obtain the voltage of the bus capacitor branch through the voltage sensor. A voltage sensor can also be provided in the power conversion device, see Figure 8As shown, the voltage sensor can be connected to the bus capacitor branch and the controller respectively to detect the voltage of the bus capacitor branch and output the detected voltage value to the controller, so that the controller can control the switching device in the first switch module based on the voltage value detected by the voltage sensor. The voltage sensor can be a device commonly used in the industry with a voltage detection function, such as a Hall sensor.

[0058] It should be noted that the structure of the power conversion device when the above-mentioned bus capacitor branches include one bus capacitor and two bus capacitors respectively is only an example. In actual application, the power conversion device can also have other topologies. For example, the bus capacitor can be composed of multiple capacitors in parallel, and the first resistor corresponding to the bus capacitor can be composed of multiple resistors in series or in parallel.

[0059] In actual application, according to the application scenario of the power conversion device, in addition to the above-mentioned components, the power conversion device may also include other functional components, which are configured separately below.

[0060] In a possible implementation, in order to achieve long-term output of electrical energy and stable output voltage for the load, the power conversion device, in addition to the above components, also includes: Figure 9 As shown, it can also include a battery pack and a battery charging and discharging circuit. Figure 9 As shown, the battery pack is connected to the first end of the battery charge and discharge circuit; the second end of the battery charge and discharge circuit is connected to the output end of the conversion circuit.

[0061] Specifically, using Figure 9 When the power conversion device shown is supplying power to a load, if the external power supply is operating normally, the conversion circuit can rectify the power output from the power supply, with a portion of the power directly powering the connected load, while the remaining portion can be used to charge the battery pack via the battery charge-discharge circuit. If the external power supply fails and cannot provide the power required for the load to operate, the battery pack's stored energy can be regulated by the battery charge-discharge circuit and then output to the connected load, thereby powering the load, thereby improving the power supply stability of the power conversion device.

[0062] The battery pack may be composed of one or more batteries. When the battery pack includes multiple batteries, the multiple batteries may be connected in series or in parallel. The battery charging and discharging circuit may use a commonly used circuit or chip with boost and buck functions in the industry, and this application does not impose specific limitations here.

[0063] In actual application, if there is electrical energy stored in the battery pack, use Figure 9In the power conversion device structure shown, the controller can also use the electrical energy stored in the battery pack to pre-charge the bus capacitor branch. The controller can control the first switch module to open when the battery pack is electrically connected to the bus capacitor branch through the battery charging and discharging circuit and the voltage of the bus capacitor branch is less than a preset threshold, and control the first switch branch to close when the voltage of the bus capacitor branch is greater than or equal to the preset threshold.

[0064] For ease of understanding, a specific example of a power conversion device is given below. Figure 7 Taking the conversion circuit structure shown in FIG. as an example, the structure of the power conversion device can be seen in FIG. Figure 10 As shown, inductor L4, inductor L5, and switches Q6 to Q9 form a charge-discharge circuit. When the bus capacitor needs to be charged, the controller controls switches K1 and K2 to turn off. The electrical energy stored in the battery pack passes through a closed path formed by inductor L4, the parasitic diode of switch Q7, resistor R1, bus capacitor C1, bus capacitor C2, resistor R2, the parasitic diode of switch Q9, and inductor L5 to pre-charge bus capacitors C1 and C2. When it is determined that bus capacitors C1 and C2 are fully charged, switches K1 and K2 are controlled to close, short-circuiting resistors R1 and R2. At this time, the conversion circuit can be controlled to operate, and the power conversion device can obtain electrical energy from the power supply through the conversion circuit and supply power to the load connected to the back end.

[0065] In one possible implementation, when a conversion circuit is used to precharge the bus capacitor branch, in order to disconnect the power supply from the conversion circuit in the event of an external power supply failure, the power conversion device further includes a second switch module connected between the conversion circuit input and the power supply. The second switch module is configured to control the connection between the conversion circuit and the power supply. The second switch module may include at least one switch. The selection and control methods of the switch can be found in the description of the first switch module in the embodiments of this application, and are not repeated here.

[0066] In one possible implementation, when a battery pack is used to precharge the bus capacitor branch, the power conversion device further includes a third switch module connected between the battery pack and the charge-discharge circuit to disconnect the battery pack from the battery charge-discharge circuit in the event of a battery pack failure. The third switch module is configured to control the connection between the battery pack and the charge-discharge circuit. The third switch module may include at least one switch. The selection and control method of the switch can be found in the description of the first switch module in the embodiments of this application, and will not be repeated here.

[0067] Based on the same concept, embodiments of the present application also provide an uninterruptible power supply (UPS), which may include an inverter and the aforementioned power conversion device. The UPS may further include a housing and multiple external interfaces provided on the housing. The power conversion device and inverter may be located within the housing and connected to a power source and a load via the multiple external interfaces on the housing.

[0068] In actual application, the input of the inverter is connected to the output of the conversion circuit, and the output of the inverter is connected to the load. The inverter can convert the DC voltage output by the conversion circuit into the AC voltage required to power the load, thereby powering the load.

[0069] In the various embodiments of the present application, unless otherwise specified or there is a logical conflict, the terms and / or descriptions between different embodiments are consistent and can be referenced by each other. The technical features in different embodiments can be combined to form new embodiments according to their inherent logical relationships.

[0070] Obviously, those skilled in the art may make various modifications and variations to this application without departing from the scope of protection of this application. Thus, if these modifications and variations of this application fall within the scope of the claims of this application and their equivalents, this application is intended to include these modifications and variations.

Claims

1. A power conversion device, characterized in that: include: Conversion circuit, bus capacitor branch, resistor module, first switch module and controller; The input end of the conversion circuit is used to be connected to a power supply, and the output end of the conversion circuit is connected to the bus capacitor branch through the resistance module; The first switch module is connected in parallel with the resistance module; The controller is connected to the first switch module and is used to control the first switch module to disconnect when the conversion circuit is connected to the power supply and the voltage of the bus capacitor branch is less than a preset threshold, and to control the first switch module to close when the voltage of the bus capacitor branch is greater than or equal to the preset threshold.

2. The device according to claim 1, characterized in that The resistor module includes a first resistor corresponding to each bus capacitor in the bus capacitor branch, and the first resistor is connected in series with the corresponding bus capacitor.

3. The device according to claim 1, characterized in that The resistors in the resistor module are thermistors.

4. The device according to claim 2 or 3, characterized in that The first switch module includes a first switch corresponding to each first resistor one by one, each first switch is connected in parallel with the corresponding first resistor, and a control end of each first switch is connected to the controller.

5. The device according to claim 1, characterized in that The power conversion device further includes: a battery pack and a battery charging and discharging circuit; The battery pack is connected to the first end of the battery charging and discharging circuit; The second end of the battery charging and discharging circuit is connected to the output end of the conversion circuit.

6. The device according to claim 5, characterized in that The controller is also used to: when the battery pack is electrically connected to the bus capacitor branch through the battery charging and discharging circuit and the voltage of the bus capacitor branch is less than the preset threshold, control the first switch module to disconnect; and when the voltage of the bus capacitor branch is greater than or equal to the preset threshold, control the first switch module to close.

7. The device according to claim 1 or 2, characterized in that The power conversion device further includes a second switch module connected between the input end of the conversion circuit and the power supply, and the second switch module is used to control the connection between the conversion circuit and the power supply.

8. The device according to claim 5 or 6, characterized in that The power conversion device further includes a third switch module connected between the battery pack and the charge and discharge circuit, and the third switch module is used to control the connection between the battery pack and the charge and discharge circuit.

9. The device according to claim 1 or 2, characterized in that The power conversion device further includes a voltage sensor, which is connected to the bus capacitor branch and the controller. The voltage sensor is used to detect the voltage of the bus capacitor branch and output the detected voltage to the controller.

10. An uninterruptible power supply, characterized in that: include: An inverter and a power conversion device according to any one of claims 1 to 9, wherein the input end of the inverter is connected to the output end of the conversion circuit, and the output end of the inverter is used to be connected to a load.

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