Bidirectional multi-level power conversion device, UPS and charging pile

Abstract

The utility model discloses a bidirectional multi-level power conversion device, a UPS (Uninterrupted Power Supply) and a charging pile, which are used for improving the power level of the power conversion device, reducing the volume of the power conversion device and reducing the cost of the power conversion device. The power conversion device comprises a capacitor branch, a filtering module and a plurality of single-phase Vienna PFC circuits which are in one-to-one correspondence with phase lines of an alternating current power supply; the first end of the capacitor branch is connected with the anode of the direct-current power supply, and the second end is connected with the cathode of the direct-current power supply; two ports of the direct current end of each single-phase Vienna PFC circuit are connected with the first end and the second end of the capacitor branch, and the alternating current end of each single-phase Vienna PFC circuit is connected with the corresponding phase line through the filtering module. Wherein each single-phase Vienna PFC circuit is composed of an inductor and a plurality of switching tubes.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power electronics, and particularly relates to a bidirectional multi-level power conversion device, a UPS and a charging pile. BACKGROUND

[0002] The power converter adopts a Vienna power factor correction (PFC) circuit topology, which is a relatively mature technology.

[0003] With the increasing demand for power, at present, multiple Vienna PFC circuits are connected in parallel in the industry to improve the power level of the equipment. Although the power conversion of a single Vienna PFC circuit is reduced, the current stress problem can be reduced, but the Vienna PFC circuit inductance current ripple is large and the device volume is large. CONTENT OF THE UTILITY MODEL

[0004] The present application provides a bidirectional multi-level power conversion device, a UPS and a charging pile, which are used to improve the power level of the power conversion device, reduce the volume of the power conversion device and reduce the cost of the power conversion device.

[0005] In a first aspect, the embodiments of the present application provide a bidirectional multi-level power conversion device, which can include a capacitor branch, a filter module and a plurality of single-phase Vienna PFC circuits corresponding to each phase line of an alternating current power supply.

[0006] Specifically, a first end of the capacitor branch is used to be connected with a positive pole of a direct current power supply, and a second end of the capacitor branch is used to be connected with a negative pole of the direct current power supply; two ports of a direct current end of each single-phase Vienna PFC circuit are connected with the first end and the second end of the capacitor branch, and an alternating current end of each single-phase Vienna PFC circuit is connected with a corresponding phase line through the filter module. Wherein, each single-phase Vienna PFC circuit is composed of an inductor and a plurality of switch tubes. When the bidirectional multi-level power conversion device works in a rectification mode, each single-phase Vienna PFC circuit converts alternating current energy transmitted on the corresponding phase line into direct current energy and outputs the direct current energy to the direct current power supply, and when the bidirectional multi-level power conversion device works in an inversion mode, each single-phase Vienna PFC converts direct current energy output by the direct current power supply into alternating current energy and outputs the alternating current energy to the corresponding phase line.

[0007] With the above design, multiple single-phase Vienna PFC circuits are configured on each phase line for transmitting alternating current. When three single-phase Vienna PFC circuits are configured on each phase line, the switches in the three single-phase Vienna PFC circuits can be controlled to work in phase opposition by 120°, and the bidirectional multi-level power conversion device is a seven-level circuit topology. When two single-phase Vienna PFC circuits are configured on each phase line, the switches in the two single-phase Vienna PFC circuits can be controlled to work in phase opposition by 180°, and the bidirectional multi-level power conversion device is a five-level circuit topology. Taking the case of two single-phase Vienna PFC circuits configured on each phase line as an example, since the switches in the two single-phase Vienna PFC circuits work in phase opposition by 180°, when one single-phase Vienna PFC circuit is in freewheeling, the other single-phase Vienna PFC circuit is in energy storage, and the current directions of the two single-phase Vienna PFC circuits are opposite. Therefore, the current ripple of the combined current transmitted to the filter module is small, and the device cost in the filter module can be reduced. In addition, since the two single-phase Vienna PFC circuits share the same filter module, compared with the parallel connection of two traditional Vienna PFC circuits, the five-level circuit topology formed by the present application can not only reduce the number of filter modules, but also reduce the specifications of the devices in the filter module, thereby reducing the cost and size of the power conversion device.

[0008] In a possible design, the inductors in the multiple single-phase Vienna PFC circuits corresponding to each phase line are coupled. With the above design, since the inductors in the multiple single-phase Vienna PFC circuits corresponding to each phase line are coupled, the total inductance of a single single-phase Vienna PFC circuit is the sum of the inductance of the inductor and the coupled inductance, so that the inductance size and cost of each single-phase Vienna PFC circuit can be reduced.

[0009] In a possible design, the inductors in the multiple single-phase Vienna PFC circuits corresponding to each phase line are wound on the same core.

[0010] In a possible design, each single-phase Vienna PFC circuit includes a first switch, a second switch, a third switch, a fourth switch, and a first inductor.

[0011] The first end of the first switch tube is connected with the first end of the capacitor branch, the second end of the first switch tube is connected with the first end of the second switch tube; the second end of the second switch tube is connected with the second end of the capacitor branch; the first end of the third switch tube is connected with the second end of the first switch tube, the second end of the third switch tube is connected with the first end of the fourth switch tube; the second end of the fourth switch tube is connected with the intermediate node of the capacitor branch; the first end of the first inductor is connected with the second end of the first switch tube, and the second end of the first inductor is connected with the filter module. If the neutral line is included in the device where the bidirectional multi-level power conversion device is located, the neutral line is connected with the intermediate node of the capacitor branch.

[0012] In a possible design, if the direct-current power supply also has an intermediate node, the intermediate node of the capacitor branch is connected with the intermediate node of the direct-current power supply, and the intermediate node of the direct-current power supply can clamp the intermediate node of the capacitor branch, thereby avoiding the voltage imbalance problem caused by the difference of capacitor devices.

[0013] In a possible implementation, the bidirectional multi-level power conversion device further includes a voltage regulation circuit, the first end of the voltage regulation circuit is connected with the first end of the capacitor branch, the second end of the voltage regulation circuit is connected with the second end of the capacitor branch, and the third end of the voltage regulation circuit is connected with the intermediate node of the capacitor branch. If the neutral line is included in the device where the bidirectional multi-level power conversion device is located, the neutral line is connected with the intermediate node of the capacitor branch and the filter module. With the above design, when the voltage imbalance of the intermediate node of the capacitor branch is caused by the difference of capacitor devices or the control strategy error of the single-phase PFC circuit control, the voltage regulation circuit can be controlled to work to transmit the electric energy of the capacitor with a higher voltage amplitude to the capacitor with a lower voltage amplitude, thereby realizing the voltage balance of the capacitor branch.

[0014] In a possible implementation, the voltage regulation circuit includes a fifth switch tube, a sixth switch tube and a second inductor.

[0015] The first end of the fifth switch tube is connected with the first end of the capacitor branch, the second end of the fifth switch tube is connected with the first end of the second inductor and the first end of the sixth switch tube; the second end of the sixth switch tube is connected with the second end of the capacitor branch; and the second end of the second inductor is connected with the intermediate node of the capacitor branch.

[0016] In a possible design, the filter module includes a filter connected with each phase line in one-to-one correspondence, and each phase line is connected with a corresponding plurality of single-phase Vienna PFC circuits through the connected filter.

[0017] In a second aspect, the embodiments of the present application provide a UPS, which can meet the power supply demand in a medium or high power supply scenario. The UPS comprises a battery pack, an inverter and at least one bidirectional multi-level power conversion device provided in the first aspect of the present application and any possible design thereof.

[0018] The first end of each bidirectional multi-level power conversion device is configured to be connected with an AC power supply, and the second end of each bidirectional multi-level power conversion device is respectively connected with the battery pack and the inverter. The inverter is configured to be connected with a load. Since the devices connected with the first end and the second end of each bidirectional multi-level power conversion device are the same, if the UPS comprises a plurality of bidirectional multi-level power conversion devices, the plurality of bidirectional multi-level power conversion devices are connected in parallel.

[0019] In a third aspect, the embodiments of the present application provide a UPS, which can meet the power supply demand in a medium or high power supply scenario. The UPS comprises a battery pack, a rectifier and at least one bidirectional multi-level power conversion device provided in the first aspect of the present application and any possible design thereof.

[0020] The AC end of the rectifier is connected with the AC power supply, and the output end of the rectifier is connected with the first end of each bidirectional multi-level power conversion device and the battery pack. The second end of each bidirectional multi-level power conversion device is configured to be connected with a load. Since the devices connected with the first end and the second end of each bidirectional multi-level power conversion device are the same, if the UPS comprises a plurality of bidirectional multi-level power conversion devices, the plurality of bidirectional multi-level power conversion devices are connected in parallel.

[0021] In a fourth aspect, the embodiments of the present application provide a charging pile, which can meet the charging demand in a medium or high power charging scenario of an electric vehicle. The charging pile comprises a bidirectional multi-level power conversion device provided in the first aspect of the present application and any possible design thereof, a DC bus and an isolation transformer.

[0022] The bidirectional multi-level power conversion device is connected with the DC bus. The bidirectional multi-level power conversion device is configured to be connected with an AC power supply, and convert AC power output by the AC power supply into DC power and transmit the DC power to the DC bus, or convert DC power of the DC bus into AC power and transmit the AC power to the AC power supply. The primary winding of the isolation transformer is connected with the DC bus, and the secondary winding of the isolation transformer is configured to be connected with an electric vehicle.

[0023] In addition, the technical effects brought by the second aspect to the fourth aspect and any possible design thereof can be referred to the technical effects brought by different designs in the first aspect of the present application, which will not be described herein. BRIEF DESCRIPTION OF DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the embodiments will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0025] Figure 1 Structure diagram of a three-phase Vienna PFC circuit commonly used in the industry Figure 1

[0026] Figure 2 Structure diagram of a bidirectional multi-level power conversion device provided by the embodiments of the present application Figure 1

[0027] Figure 3 Current waveform diagram of the bidirectional multi-level power conversion device provided by the embodiments of the present application

[0028] Figure 4 Voltage waveform diagram of the bidirectional multi-level power conversion device provided by the embodiments of the present application

[0029] Figure 5 Structure diagram of a single-phase Vienna PFC circuit provided by the embodiments of the present application

[0030] Figure 6 Structure diagram of a bidirectional multi-level power conversion device provided by the embodiments of the present application Figure 2

[0031] Figure 7 Energy transmission mode diagram of the bidirectional multi-level power conversion device provided by the embodiments of the present application

[0032] Figure 8 Structure diagram of a bidirectional multi-level power conversion device provided by the embodiments of the present application Figure 3

[0033] Figure 9 Structure diagram of a bidirectional multi-level power conversion device provided by the embodiments of the present application Figure 4

[0034] Figure 10 Structure diagram of a bidirectional multi-level power conversion device provided by the embodiments of the present application Figure 5

[0035] Figure 11 Structure diagram of a UPS provided by the embodiments of the present application Figure 1 ​​​​​​​

[0036] Figure 12 A structure diagram of a UPS provided for an embodiment of the present application Figure 2 ;

[0037] Figure 13 A structure diagram of a UPS provided for an embodiment of the present application Figure 3 ;

[0038] Figure 14 A structure diagram of a charging pile provided for an embodiment of the present application. DETAILED DESCRIPTION

[0039] The embodiments of the present application will be described in detail below with reference to the drawings.

[0040] The terms used in the embodiments of the present application are only used to explain the specific embodiments of the present application, and are not intended to limit the present application. Obviously, the described embodiments are only some of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor are within the scope of protection of the present application.

[0041] It should be noted that the terms "first", "second", and the like in the specification and claims of the present application and the above-described drawings are used to distinguish similar objects, and do not necessarily have to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein. The embodiments described in the following exemplary embodiments do not represent all the embodiments consistent with the present application. Rather, they are only examples of devices and methods consistent with some aspects of the present application as detailed in the appended claims.

[0042] In the following, some terms in the embodiments of the present application are explained and described in order to facilitate understanding by those skilled in the art.

[0043] (1) The term "a plurality of" in the embodiments of the present application means two or more, and other quantifiers are similar.

[0044] (2) The switching transistor in the embodiments of this application 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), and insulated gate bipolar transistors (IGBTs). These will not be listed one by one in the embodiments of this application.

[0045] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. The power conversion device provided in the embodiments of this application is applied to equipment with rectification function requirements, and can also be applied to equipment with rectification and inverter functions. For example, the power conversion device can be applied to a UPS and serve as a rectifier within the UPS. The power conversion device can convert the electrical energy from the power grid connected to the UPS into the supply voltage of the DC bus or battery pack, and supply power to the battery pack or DC bus. The power conversion device can also serve as an inverter device, converting the DC power energy from the battery pack into AC power energy and transmitting it to the power grid. The battery pack can be a battery pack built into the UPS or an external battery pack connected to the UPS.

[0046] It should be noted that the above-mentioned application of the power conversion device in UPS is only an example. In actual applications, the power conversion device can also be applied to other devices. For example, the power conversion device can be applied to new energy grid connection scenarios or other scenarios, which will not be described in detail here.

[0047] In practical applications, power conversion devices often use the traditional three-phase Vienna PFC circuit topology as the rectifier within the UPS. (See [link to relevant documentation]). Figure 1 The diagram shows a typical three-phase Vienna PFC circuit, commonly used in the industry. When the UPS has a high transmission power, multiple three-phase Vienna PFC circuits are typically connected in parallel to increase the UPS's power rating. For example, if the UPS requires a power rating of 150kW, and a single three-phase Vienna PFC circuit has a conversion power of 50kW, then three three-phase Vienna PFC circuits can be connected in parallel to meet the UPS's power requirements. However, this method of connecting multiple three-phase Vienna PFC circuits in parallel increases the size of the equipment and the cost of components, and also results in larger current ripple in the circuit.

[0048] Based on this, embodiments of this application provide a bidirectional multilevel power conversion device and a UPS, which are used to increase the power level of the power conversion device, reduce the size of the power conversion device, and lower the cost of the power conversion device.

[0049] Referring to Figure 2 Fig. 1 shows a structural schematic diagram of a bidirectional multi-level power conversion device provided by an embodiment of the present application. As shown in Figure 2 Fig. 1, the bidirectional multi-level power conversion device can include a capacitor branch, a filter module, and a plurality of single-phase Vienna PFC circuits corresponding to each phase line of an alternating current power source.

[0050] Specifically, a first end of the capacitor branch is configured to be connected to a positive pole of a direct current power source, and a second end of the capacitor branch is configured to be connected to a negative pole of the direct current power source. Two ports of a direct current end of each single-phase Vienna PFC circuit are connected to the first end and the second end of the capacitor branch, and an alternating current end of each single-phase Vienna PFC circuit is connected to a corresponding phase line through the filter module. Each single-phase Vienna PFC circuit is composed of an inductor and a plurality of switching tubes.

[0051] The bidirectional multi-level power conversion device shown in Figure 2 Fig. 1 can realize bidirectional transmission of electric energy, i.e., the multi-level power conversion device can work in a rectification mode or an inversion mode. When the bidirectional multi-level power conversion device works in the rectification mode, the alternating current power source serves as an input power source, and a plurality of single-phase Vienna PFC circuits are connected to each phase line transmitting alternating current. Each single-phase Vienna PFC circuit converts the alternating current energy transmitted on the corresponding phase line into direct current energy and outputs the direct current energy to the direct current power source, and charges the direct current power source. When the bidirectional multi-level power conversion device works in the inversion mode, the direct current power source serves as an input power source and is connected to the direct current end of each single-phase Vienna PFC circuit. Each single-phase Vienna PFC converts the direct current energy output by the direct current power source into alternating current energy and outputs the alternating current energy to the corresponding phase line. If the alternating current power source is a three-phase alternating current power source, a single-phase alternating current is output on each phase line, and the single-phase alternating currents transmitted on the three phase lines have a phase difference of 120°. The three single-phase alternating currents with a phase difference of 120° constitute a three-phase alternating current.

[0052] In actual application, in order to filter the electric signals on each phase line, the filter module can include filters corresponding to each phase line. Each phase line is connected to the alternating current end of the corresponding plurality of single-phase Vienna PFC circuits through the connected filter, and each filter can filter the electric signals on the connected phase line. The filter can adopt a T-type filter or an LC filter, and of course, other circuit topologies with filtering functions commonly used in the industry can also be adopted, which are not limited herein.

[0053] It should be understood that Figure 2The illustrated bidirectional multilevel power conversion device structure is merely an example of a bidirectional multilevel power conversion device connected to a three-phase AC power supply. The bidirectional multilevel power conversion device can also be connected to a single-phase AC power supply. Furthermore, the bidirectional multilevel power conversion device can have a higher... Figure 2 The additional components shown, for example, the bidirectional multilevel power conversion device may also include overload protection devices and short-circuit protection devices. Of course, the bidirectional multilevel power conversion device may also include other functional devices, which will not be described in detail here.

[0054] In practical applications, the bidirectional multilevel power conversion device can be connected to both DC and AC power sources. The capacitor branch can be connected to the DC power source as a DC bus for voltage stabilization. The AC power source can be single-phase or three-phase, and can be either a power grid or a new energy power generation system.

[0055] In practical applications, when a bidirectional multilevel power conversion device is connected to a three-phase AC power supply, the three-phase AC output can consist of single-phase AC power in phases A, B, and C. This three-phase AC power can be transmitted using a three-phase three-wire system or a three-phase four-wire system. If a three-phase three-wire system is used, the connection between the three-phase AC power supply and the power conversion device includes three phase wires for transmitting the single-phase AC power in phases A, B, and C, respectively. If a three-phase four-wire system is used, the connection between the three-phase AC power supply and the power conversion device includes three phase wires for transmitting the single-phase AC power in phases A, B, and C, respectively, and also includes a neutral wire N. Multiple single-phase Vienna PFC circuits are configured for each phase wire transmitting the single-phase AC power.

[0056] See Figure 2 As shown, multiple single-phase Vienna PFC circuits corresponding to each phase line are connected in parallel, and each single-phase Vienna PFC circuit includes an inductor and multiple switching devices. These switching devices are all electrically controlled and can be turned on and off according to received voltage or current signals. When two single-phase Vienna PFC circuits are configured for each phase line, the switching transistors in the two circuits can be controlled to operate at a 180° phase shift by configuring appropriate voltage or current signals. In this case, the bidirectional multilevel power conversion device is a five-level circuit topology. When three single-phase Vienna PFC circuits are configured for each phase line, the switching transistors in the three circuits can be controlled to operate at a 120° phase shift by configuring appropriate voltage or current signals. In this case, the bidirectional multilevel power conversion device is a seven-level circuit topology.

[0057] Using the bidirectional multilevel power conversion device provided in this application embodiment, taking the configuration of two single-phase Vienna PFC circuits per phase line as an example, since the switching transistors in the two single-phase Vienna PFC circuits operate at 180° phase shift, the current on each phase line can be seen from... Figure 3 As shown, when a single-phase Vienna PFC circuit performs freewheeling, the current in the circuit... i As 1 gradually decreases, another single-phase Vienna PFC circuit performs energy storage current on the circuit. i 2. As the current gradually increases, the current in the two single-phase Vienna PFC circuits... i 1 and i The amplitude changes of phases 2 are in opposite directions; therefore, the currents from the two single-phase Vienna PFC circuits are combined and then transmitted to the filter module. i Reduced ripple in the output circuit can decrease the component cost of the filter module. When one single-phase Vienna PFC circuit operates in freewheeling mode and the other in energy storage mode, the circuit outputs a +1 / 2 level if the AC current is in the positive half-cycle, and a -1 / 2 level if the AC current is in the negative half-cycle. The output waveform can be found in [reference needed]. Figure 4 As shown, the bidirectional multi-level power conversion device constitutes a five-level circuit topology. Furthermore, since the two single-phase Vienna PFC circuits reuse the same filter module, the number of filter modules can be further reduced. Therefore, compared to the parallel connection of two traditional three-phase Vienna PFC circuits, the solution of this application not only reduces the cost of the filter modules but also reduces the number of filter modules, thereby increasing the power conversion device's power rating while simultaneously reducing the cost and size of the power conversion device.

[0058] In practical applications, to reduce the cost of inductors in single-phase Vienna PFC circuits, inductors in multiple single-phase Vienna PFC circuits corresponding to each phase line can be coupled. In this case, the total inductance of each single-phase Vienna PFC circuit is the sum of the inductance of the inductor and the coupling inductance, thereby reducing the size and cost of the inductors in each single-phase Vienna PFC circuit. The inductors in multiple single-phase Vienna PFC circuits corresponding to each phase line can be wound around the same iron core to achieve inductor coupling. Of course, other coupling methods can also be used for the inductors in multiple single-phase Vienna PFC circuits corresponding to each phase line, and this application does not specifically limit this.

[0059] In practical applications, the structure of a single-phase Vienna PFC circuit can be found in the traditional single-bridge-arm single-phase Vienna PFC topology. To reduce device losses during the freewheeling process in a single-phase Vienna PFC topology, switching transistors can be used instead of diodes. For details, see [link to relevant documentation]. Figure 4As shown, each single-phase Vienna PFC circuit includes: a first switch Q1, a second switch Q2, a third switch Q3, a fourth switch Q4, and a first inductor L1. The first terminal of the first switch Q1 is connected to the first terminal of the capacitor branch, and the second terminal of the first switch Q1 is connected to the first terminal of the second switch Q2. The second terminal of the second switch Q2 is connected to the second terminal of the capacitor branch. The first terminal of the third switch Q3 is connected to the second terminal of the first switch Q1, and the second terminal of the third switch Q3 is connected to the first terminal of the fourth switch Q4. The second terminal of the fourth switch Q4 is connected to the intermediate node of the capacitor branch. The first terminal of the first inductor L1 is connected to the second terminal of the first switch Q1, and the second terminal of the first inductor L1 is connected to the filter module. See also... Figure 4 As shown, when the current in a single-phase Vienna PFC circuit switches from switching transistors Q3 and Q4 to switching transistors Q1 or Q2 for freewheeling, the power loss of the switching transistors is lower than that of diodes conducting freewheeling, which helps to reduce the energy consumption of the single-phase Vienna PFC circuit during operation.

[0060] The following is based on Figure 4 Taking the single-phase Vienna PFC circuit structure shown as an example, the structure of the power conversion device is as follows: Figure 5 As shown, Figure 5 As shown, A, B, and C can serve as external interfaces for the power conversion device, connecting to the three phase lines of the three-phase AC power supply, which transmits phase A, phase B, and phase C AC power, respectively. Capacitors C1 and C2 are connected in series to form a capacitor branch serving as the DC bus. The positive busbar BUS+ and negative busbar BUS- of the DC busbar are connected to the positive terminal BAT+ and negative terminal BAT- of the DC power supply, respectively. The inductor and multiple switching transistors form a T-shaped network, constituting a... Figure 5 The single-phase Vienna PFC circuit topology shown can be configured such that each single-phase Vienna PFC circuit can be connected to the corresponding phase line via a filter consisting of two inductors and one capacitor, for example, see [link to example]. Figure 6 As shown, the two single-phase Vienna PFC circuits corresponding to the phase line transmitting phase A AC power can be connected by a filter composed of inductor L4, inductor L1 and Ca.

[0061] use Figures 2 to 6 The bidirectional multilevel power converter shown can realize bidirectional power transmission, meaning it can operate in both rectification and inverter modes. See also... Figure 7As shown, when the bidirectional multi-level power conversion device works in the rectification mode, the port A, the port B and the port C are input terminals of the bidirectional multi-level power conversion device, and the two ends BUS+ and BUS- of the DC bus are output terminals. The bidirectional multi-level power conversion device can obtain the alternating current energy output by the alternating current power through the input terminals, rectify the alternating current energy into direct current energy and output the direct current energy to the direct current power through the output terminals. When the bidirectional multi-level power conversion device works in the inversion mode, the two ends BUS+ and BUS- of the DC bus are input terminals, and the port A, the port B and the port C are output terminals of the bidirectional multi-level power conversion device. The bidirectional multi-level power conversion device can obtain the direct current energy output by the direct current power through the input terminals, invert the direct current energy into alternating current energy and output the alternating current energy to the power grid through the output terminals. The rectification process and the inversion process of the bidirectional multi-level power conversion device can be known from the working process of the Vienna PFC circuit, which will not be described in detail herein.

[0062] In actual application, due to the production of devices and other reasons, the capacitance C1 and the capacitance C2 may be different, so that the voltages at the two ends of the capacitance C1 and the capacitance C2 are different during the operation of the power conversion device, and the phenomenon of unbalanced bus voltage occurs. If the direct current power further includes an intermediate node in addition to the positive electrode BAT+ and the negative electrode BAT-, referring to Figure 5 As shown, the intermediate nodes of the capacitance C1 and the capacitance C2 can be connected to the intermediate node of the direct current power, and the voltages at the two ends of the capacitance C1 and the capacitance C2 are clamped through the intermediate node of the direct current power, so as to ensure the stable bus voltage. For the direct current power without the intermediate node, the voltages at the two ends of the two capacitances can be adjusted through the configuration of the voltage regulating circuit, so as to realize the balanced bus voltage.

[0063] In a possible implementation, the voltage regulating circuit includes a fifth switch tube, a sixth switch tube and a second inductor. The first end of the fifth switch tube is connected to the first end of the capacitance branch, the second end of the fifth switch tube is connected to the first end of the second inductor and the first end of the sixth switch tube, the second end of the sixth switch tube is connected to the second end of the capacitance branch, and the second end of the second inductor is connected to the intermediate node of the capacitance branch. As shown in the circuit, Figure 5 As shown in the circuit, the structure of the bidirectional multi-level power conversion device after the configuration of the voltage regulating circuit can be referred to Figure 8 As shown, the switch tube Q25 constitutes the fifth switch tube, the switch tube Q26 constitutes the sixth switch tube, and the inductor L7 constitutes the second inductor.

[0064] It should be noted that, Figures 5 to 8The illustrated bidirectional multilevel power conversion device structure is an example of a three-phase AC power supply using a three-phase three-wire system for energy transmission. For instance, when the bidirectional multilevel power conversion device is applied to a charging station, the charging station may not have a neutral line, only the three phase lines for transmitting three-phase AC power. In practical applications, the three-phase AC power supply can also use a three-phase four-wire system for energy transmission. For example, when the bidirectional multilevel power conversion device is applied to a UPS, the UPS is equipped with a neutral line N. Therefore, see [link to relevant documentation]. Figure 9 As shown, the bidirectional multilevel power conversion device includes a port N connected to the neutral line, in addition to ports A, B, and C that can be connected to the three phase lines transmitting phase A AC, phase B AC, and phase C AC, respectively. Port N can be connected to the intermediate node of capacitors C1 and C2, and to the second terminal of capacitors Ca, Cb, and Cc.

[0065] In practical applications, due to manufacturing limitations, capacitors C1 and C2 in power conversion devices connected to port N (neutral line N) may differ, resulting in different voltages across them during operation and causing bus voltage imbalance. If the DC power supply includes a neutral point in addition to the positive terminals BAT+ and BAT-, the intermediate node of capacitors C1 and C2 can be connected to the intermediate node of the DC power supply. This intermediate node clamps the voltage across C1 and C2, ensuring stable bus voltage. For scenarios where the DC power supply only has two external interfaces (positive BAT+ and negative BAT-), a voltage regulator circuit can be configured to adjust the voltage across the two capacitors, achieving bus voltage balance. The structure of the bidirectional multilevel power conversion device with the voltage regulator circuit can be found in [reference needed]. Figure 10 As shown.

[0066] use Figures 5 to 10 The bidirectional multilevel power conversion device shown achieves inductive coupling among multiple single-phase Vienna PFC circuits by winding the inductors of each phase line onto the same iron core. Of course, other methods can also be used for inductive coupling, such as autotransformers. In these autotransformer windings, the number of coils in the inductors of each phase line is the same, thereby achieving current sharing among the inductors of each phase line. However, other current sharing methods can also be used in the bidirectional multilevel power conversion device provided in this application embodiment, and this application embodiment does not limit this approach.

[0067] It needs to be explained that, Figures 5 to 10As an example of the structure of the bidirectional multi-level power conversion device connected with the three-phase AC power supply and each phase line configured with two single-phase Vienna PFC circuits, in actual application, according to the type of the AC power supply connected with the bidirectional multi-level power conversion device, the number of the single-phase Vienna PFC circuits corresponding to each phase line, and the structure of the filter, the bidirectional multi-level power conversion device provided by the embodiments of the present application can also have other circuit topologies, which are not introduced here.

[0068] In actual application, all the devices in the bidirectional multi-level power conversion device can be integrated in a cabinet, and the cabinet is configured with external interfaces connected with the DC power supply and the AC power supply respectively, and the DC power supply and the AC power supply can be connected with the bidirectional multi-level power conversion device through the external interfaces.

[0069] In an embodiment, the bidirectional multi-level power conversion device can be integrated with other devices in the same cabinet. If the bidirectional multi-level power conversion device and the other devices in the equipment are located on different printed circuit boards (PCB), the PCB on which the bidirectional multi-level power conversion device is located also has a connector, and the bidirectional multi-level power conversion device can be connected with the other devices in the equipment through the connector and a cable.

[0070] In combination with the above description, the embodiments of the present application also provide a UPS, as shown in Figure 11 The UPS can include a battery pack, an inverter and at least one of the aforementioned power conversion devices. The UPS can be externally connected with the battery pack or internally configured with the battery pack.

[0071] Specifically, the first end of each bidirectional multi-level power conversion device is used to be connected with the AC power supply, and the second end of each bidirectional multi-level power conversion device is connected with the battery pack and the inverter. The AC power supply output can be rectified into DC power, and the DC power can be output to the inverter and used to charge the battery pack. The inverter is used to be connected with the load, and the DC power output by the bidirectional multi-level power conversion device can be inverted into AC power to supply power to the connected load. The structure of the power conversion device can refer to the foregoing related description, which is not repeated here.

[0072] The UPS provided by the embodiments of the present application can also reversely transmit the power of the battery pack to the power grid. By controlling the bidirectional multi-level power conversion device to work in the inverting state, the DC power can be obtained from the battery pack or the DC bus connected with the second end, and the obtained DC power can be inverted into AC power and output to the power grid.

[0073] In practical applications, if the UPS is applied to a medium or high power supply scene, and the working power of a single bidirectional multi-level power conversion device cannot meet the demand of the UPS for working power, multiple parallel bidirectional multi-level power conversion devices can be configured to improve the power level of the UPS.

[0074] It should be noted that, Figure 11 The UPS is a circuit topology of the bidirectional multi-level power conversion device as a rectifier, and in practical applications, the bidirectional multi-level power conversion device can also be used as an inverter in the UPS, as shown in Figure 12 The UPS is a circuit topology of the bidirectional multi-level power conversion device as a rectifier, and in practical applications, the bidirectional multi-level power conversion device can also be used as an inverter in the UPS, as shown in Figure 12 The UPS includes a battery pack, a rectifier, and the aforementioned bidirectional multi-level power conversion device.

[0075] The AC end of the rectifier is connected to an AC power source, the output end of the rectifier is connected to the first end of each bidirectional multi-level power conversion device and the battery pack, and the second end of each bidirectional multi-level power conversion device is used to be connected to a load.

[0076] In practical applications, if the UPS is applied to a medium or high power supply scene, and the working power of a single bidirectional multi-level power conversion device cannot meet the demand of the UPS for working power, multiple parallel bidirectional multi-level power conversion devices can be configured to improve the power level of the UPS.

[0077] It should be noted that, Figure 11 and Figure 12 are circuit topologies of the UPS when the bidirectional multi-level power conversion device is used as a rectifier and an inverter, respectively, and in practical applications, the bidirectional multi-level power conversion device can also be used as an inverter and a rectifier in the UPS, and the circuit topology can be referred to Figure 13 .

[0078] It should be noted that the above-mentioned UPS is only an example of an application scenario of the bidirectional multi-level power conversion device, and in practical applications, the bidirectional multi-level power conversion device can also be applied to other devices, for example, the bidirectional multi-level power conversion device can be applied to new energy grid-connected devices or charging piles and the like.

[0079] Based on the above description, the embodiment of the present application further provides a charging pile which can be connected to a power grid and plugged into and out of a charging port of an electric vehicle. The charging pile can convert the electric energy of the power grid into the charging voltage of the electric vehicle and charge the power battery in the electric vehicle. The charging pile can also obtain the direct-current electric energy of the power battery through the charging port of the electric vehicle, convert it into the grid voltage, and supply power to the power grid. As shown in Figure 14 The charging pile can include the aforementioned bidirectional multi-level power conversion device, a direct-current bus, and an isolation transformer.

[0080] The bidirectional multi-level power conversion device is connected with the DC bus, and is used for connecting with the AC power supply and converting AC power output by the AC power supply into DC power and transmitting the DC power to the DC bus, or converting DC power of the DC bus into AC power and transmitting the AC power to the AC power supply; the primary winding of the isolation transformer is connected with the DC bus, and the secondary winding of the isolation transformer is used for connecting with the electric vehicle.

[0081] In each embodiment of the present application, the terms and / or descriptions of different embodiments are consistent and can be referred to each other if there is no special description and logical conflict, and the technical features in different embodiments can be combined to form new embodiments according to their inherent logical relationship.

[0082] Obviously, various modifications and variations of the present application can be made by those skilled in the art without departing from the scope of the application. Thus, it is intended that the present application include modifications and variations of the application provided they come within the scope of the claims and their equivalents.

Claims

1. A bidirectional multi-level power conversion device, characterized by, The application relates to a bidirectional multi-level power conversion device. The application relates to a bidirectional multi-level power conversion device. The application relates to a bidirectional multi-level power conversion device. The application relates to a bidirectional multi-level power conversion device. The application relates to a bidirectional multi-level power conversion device.

2. The apparatus of claim 1, wherein, The application relates to a bidirectional multi-level power conversion device.

3. The apparatus of claim 2, wherein, The application relates to a bidirectional multi-level power conversion device.

4. The apparatus of claim 1, wherein, The application relates to a bidirectional multi-level power conversion device. The application relates to a bidirectional multi-level power conversion device. The application relates to a bidirectional multi-level power conversion device. The application relates to a bidirectional multi-level power conversion device. The application relates to a bidirectional multi-level power conversion device. The application relates to a bidirectional multi-level power conversion device.

5. The apparatus of claim 1, wherein, The application relates to a bidirectional multi-level power conversion device.

6. The apparatus of claim 1, wherein, The application relates to a bidirectional multi-level power conversion device.

7. The apparatus of claim 6, wherein, The application relates to a bidirectional multi-level power conversion device. The application relates to a bidirectional multi-level power conversion device. The application relates to a bidirectional multi-level power conversion device. The application relates to a bidirectional multi-level power conversion device.

8. The apparatus of claim 1, wherein, The application relates to a bidirectional multi-level power conversion device.

9. A UPS characterized by, The application relates to a bidirectional multi-level power conversion device. The application relates to a bidirectional multi-level power conversion device. The application relates to a bidirectional multi-level power conversion device. The application relates to a bidirectional multi-level power conversion device.

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11. A charging station, characterized in that The bidirectional multi-level power conversion device, a DC bus and an isolation transformer are included as claimed in any one of claims 1-8; The bidirectional multi-level power conversion device is connected with the DC bus, and is used for being connected with the AC power supply, and converting AC power output by the AC power supply into DC power and transmitting the DC power to the DC bus, or converting DC power of the DC bus into AC power and transmitting the AC power to the AC power supply; A primary winding of the isolation transformer is connected with the DC bus, and a secondary winding of the isolation transformer is used for being connected with an electric vehicle.

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