Method for hot-connecting energy storage cabinet with bidirectional half-bridge DC-DC converter to DC bus

Abstract

The present invention provides a method for hot-connecting an energy storage cabinet with a bidirectional half-bridge DC-DC converter to a DC bus, as well as a bidirectional half-bridge DC-DC converter, a controller of the energy storage cabinet, and a computer-readable storage medium. When the energy storage cabinet is connected to the DC bus, one end of the inductor L1 of the bidirectional half-bridge DC-DC converter, the resistor R1, and the positive electrode of the DC bus are connected through the first switch K1, so that a loop is formed between the positive electrode of the DC bus, the resistor R1, the capacitor C2, and the negative electrode of the DC bus, and the capacitor C2 is slowly charged by the current limiting resistor R1 until the voltage across the capacitor C2 is close to the DC bus voltage, and then the capacitor C2 is connected to the DC bus. The present invention solves the problem that the energy storage cabinet with a bidirectional half-bridge DC-DC converter in the related art cannot be hot-connected to the DC bus, ensuring that the energy storage cabinet is not damaged due to excessive charging impact current when connected.

Description

Technical Field

[0001] The present invention relates to the field of direct current microgrids, and in particular to a bidirectional half-bridge DC-DC converter with a direct current bus hot-access function, an energy storage cabinet, a method for hot-accessing the energy storage cabinet to a direct current bus, a controller of the energy storage cabinet, and a computer-readable storage medium. Background Art

[0002] In a DC microgrid system or a photovoltaic storage system, the energy storage cabinet used has its own energy storage DC-DC converter, which is generally a bidirectional DC-DC converter, such as a bidirectional half-bridge DC-DC converter. In this system, one end of the bidirectional DC-DC converter in the energy storage cabinet is connected to the battery of the energy storage cabinet, and the other end is directly connected to the high-voltage DC bus of the converter; and a capacitor is connected between the positive terminal of the DC bus and the negative terminal of the DC bus on the high-voltage DC bus side of the bidirectional DC-DC converter. If the capacitor is directly connected to the DC bus, the capacitor will be damaged by the instantaneous charging current shock. Therefore, the energy storage cabinet with a bidirectional DC-DC converter cannot be hot-connected to the running DC bus, and live plugging and unplugging cannot be achieved. If the energy storage cabinet needs to be maintained, expanded or replaced during operation, the entire DC microgrid system or photovoltaic storage system must be powered off, which affects the user experience and the overall operating efficiency of the system. Summary of the invention

[0003] The present invention provides a bidirectional half-bridge DC-DC converter with a hot-access DC bus function, an energy storage cabinet, a method for hot-accessing the energy storage cabinet to a DC bus, a controller of the energy storage cabinet, and a computer-readable storage medium, so as to solve the problem in the related art that the energy storage cabinet with a bidirectional half-bridge DC-DC converter cannot be hot-accessed to the DC bus.

[0004] In a first aspect, an embodiment of the present invention provides a bidirectional half-bridge DC-DC converter, comprising a first switch tube Q1, a second switch tube Q2 and an inductor L1, characterized in that the bidirectional half-bridge DC-DC converter also includes: a capacitor C2, a first switch K1, a second switch K2 and a resistor R1, wherein the source of the first switch tube Q1, the drain of the second switch tube Q2, and one end of the inductor L1 are connected; the other end of the inductor L1, the positive terminal of the battery, and one end of the resistor R1 are connected; the first switch K1 is connected between the other end of the resistor R1 and the positive terminal of the DC bus; the second switch K2 is connected between the drain of the first switch tube and the positive terminal of the DC bus; the negative terminal of the battery, the source of the second switch tube Q2, and the negative terminal of the DC bus are connected; the capacitor C2 is connected between the drain of the first switch tube Q1 and the source of the second switch tube Q2.

[0005] Optionally, the bidirectional half-bridge DC-DC converter further includes: a third switch K3, a fourth switch K4 and a fifth switch K5, wherein the third switch K3 is connected between the other end of the inductor L1 and the positive terminal of the battery; the fourth switch K4 is connected between the other end of the resistor R1 and the positive terminal of the battery; and the fifth switch K5 is connected between the source of the second switch tube Q2 and the negative terminal of the battery.

[0006] Optionally, one or more switches among the first switch K1 , the second switch K2 , the third switch K3 , the fourth switch K4 and the fifth switch K5 are relays or contactors.

[0007] In a second aspect, an embodiment of the present invention provides an energy storage cabinet, comprising: a battery, a controller and an auxiliary power supply, and the energy storage cabinet also includes the bidirectional half-bridge DC-DC converter described in the first aspect.

[0008] Optionally, the auxiliary power supply is used to supply power to the controller after taking power from the DC bus.

[0009] Optionally, the controller is used to collect the voltage of the DC bus, collect the voltage across the capacitor C2, and control the on and off of the first switch tube Q1, the first switch K1, the second switch K2, the third switch K3, and the fifth switch K5.

[0010] In a third aspect, an embodiment of the present invention provides a method for hot-connecting an energy storage cabinet of the second aspect to a DC bus, comprising: after the DC bus positive terminal and the DC bus negative terminal of the energy storage cabinet are connected to the DC bus, the controller controls the first switch K1 to close and the first switch tube Q1 to turn on; the controller samples the DC bus voltage U1 and the voltage U2 across the capacitor C2, and determines whether the voltage U2 across the capacitor C2 is close to the DC bus voltage U1; when it is determined that the voltage U2 across the capacitor C2 is close to the DC bus voltage U1, the controller controls the second switch K2 to close, and then controls the first switch K1 and the first switch tube Q1 to disconnect.

[0011] Optionally, the method further includes: before the DC bus positive terminal and the DC bus negative terminal of the energy storage cabinet are connected to the DC bus, controlling the first switch K1, the second switch K2, the third switch K3, the fourth switch K4, the fifth switch K5, the first switch tube Q1, and the second switch tube Q2 to be disconnected.

[0012] In a fourth aspect, an embodiment of the present invention provides a controller for an energy storage cabinet, comprising: at least one processor, at least one memory, and computer program instructions stored in the memory, wherein when the computer program instructions are executed by the processor, the method described in the third aspect is implemented.

[0013] In a fifth aspect, an embodiment of the present invention provides a computer-readable storage medium having computer program instructions stored thereon, which implement the method described in the third aspect when the computer program instructions are executed by a processor.

[0014] By means of the method for hot-connecting an energy storage cabinet with a bidirectional half-bridge DC-DC converter to a DC bus, as well as the bidirectional half-bridge DC-DC converter, the controller of the energy storage cabinet and the computer-readable storage medium provided in the embodiment of the present invention, when the energy storage cabinet is connected to the DC bus, one end of the inductor L1 of the bidirectional half-bridge DC-DC converter, the resistor R1 and the positive electrode of the DC bus are connected through the first switch K1, so that a loop is formed between the positive electrode of the DC bus, the resistor R1, the capacitor C2 and the negative electrode of the DC bus, and the capacitor C2 is slowly charged by the current limiting resistor R1 until the voltage across the capacitor C2 is close to the DC bus voltage, and then the capacitor C2 is connected to the DC bus, thereby solving the problem in the related art that the energy storage cabinet with a bidirectional half-bridge DC-DC converter cannot be hot-connected to the DC bus, and ensuring that the energy storage cabinet is not damaged due to excessive charging impact current when connected. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of this application. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0016] Figure 1 is a topological structure diagram of a bidirectional half-bridge DC-DC converter according to an embodiment of the present invention;

[0017] Figure 2 The preferred topology structure of the bidirectional half-bridge DC-DC converter according to the embodiment of the present invention is Figure 1 ;

[0018] Figure 3 is a flow chart of a method for hot-connecting an energy storage cabinet to a DC bus according to an embodiment of the present invention;

[0019] Figure 4 4 is a schematic diagram of the hardware structure of the controller of the energy storage cabinet according to an embodiment of the present invention. DETAILED DESCRIPTION

[0020] The features and exemplary embodiments of various aspects of the present invention will be described in detail below. In order to make the purpose, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings and Examples. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can be implemented without the need for some of these specific details. The following description of the embodiments is only to provide a better understanding of the present invention by illustrating examples of the present invention.

[0021] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the statement "include..." do not exclude the presence of other identical elements in the process, method, article or device including the elements.

[0022] In this embodiment, a bidirectional half-bridge DC-DC converter is provided. Figure 1 is a topological diagram of a bidirectional half-bridge DC-DC converter according to an embodiment of the present invention, such as Figure 1 As shown, the bidirectional half-bridge DC-DC converter includes: a first switch tube Q1, a second switch tube Q2 and an inductor L1, and also includes: a capacitor C2, a first switch K1, a second switch K2 and a resistor R1, wherein:

[0023] The source of the first switch tube Q1, the drain of the second switch tube Q2, and one end of the inductor L1 are connected; the other end of the inductor L1, the positive terminal of the battery, and one end of the resistor R1 are connected; the first switch K1 is connected between the other end of the resistor R1 and the positive terminal of the DC bus; the second switch K2 is connected between the drain of the first switch tube and the positive terminal of the DC bus; the negative terminal of the battery, the source of the second switch tube Q2, and the negative terminal of the DC bus are connected; the capacitor C2 is connected between the drain of the first switch tube Q1 and the source of the second switch tube Q2.

[0024] When the above-mentioned bidirectional half-bridge DC-DC converter is used in an energy storage cabinet, the energy storage cabinet can be hot-connected to the DC bus by controlling each switch in the bidirectional half-bridge DC-DC converter, and it is ensured that the energy storage cabinet is not damaged due to excessive charging impact current when connected; in addition, since the charging process of the capacitor C2 is slow and controllable, it will not cause abnormal fluctuations in the output power of the DC bus.

[0025] refer to Figure 2 Optionally, in order to ensure the connection and reliable disconnection between the battery in the energy storage cabinet and the bidirectional half-bridge DC-DC converter, the bidirectional half-bridge DC-DC converter further includes: a third switch K3, a fourth switch K4 and a fifth switch K5, wherein the third switch K3 is connected between the other end of the inductor L1 and the positive terminal of the battery; the fourth switch K4 is connected between the other end of the resistor R1 and the positive terminal of the battery; and the fifth switch K5 is connected between the source of the second switch tube Q2 and the negative terminal of the battery.

[0026] Optionally, one or more switches among the first switch K1 , the second switch K2 , the third switch K3 , the fourth switch K4 and the fifth switch K5 are relays or contactors.

[0027] In this embodiment, an energy storage cabinet is provided. Figure 2 is a topological structure diagram of the electrical part of an energy storage cabinet with a bidirectional half-bridge DC-DC converter according to an embodiment of the present invention, such as Figure 2 As shown, the electrical part of the energy storage cabinet includes: a battery, a controller and an auxiliary power supply, and the energy storage cabinet also includes the above-mentioned bidirectional half-bridge DC-DC converter.

[0028] Optionally, an auxiliary power supply is used to supply power to the controller after taking power from the DC bus.

[0029] Optionally, the controller is used to collect the voltage of the DC bus, the voltage across the capacitor C2, and control the on and off of the first switch tube Q1, the first switch K1, the second switch K2, the third switch K3, and the fifth switch K5.

[0030] In the above circuit structure, the values ​​of the resistors, inductors and capacitors are not limited and can be adjusted according to actual measured data.

[0031] The control process of hot-accessing the DC bus by the bidirectional half-bridge DC-DC converter and the energy storage cabinet provided by the above-mentioned embodiment of the present invention will be further described and illustrated in the subsequent embodiments. The above-mentioned bidirectional half-bridge DC-DC converter and the energy storage cabinet have the following advantages: On the one hand, since the above-mentioned bidirectional half-bridge DC-DC converter is based on the topological structure of the existing bidirectional half-bridge DC-DC converter, with an additional control switch and improved control logic, there is no need to add energy-consuming components, there is no power loss, and the circuit structure is simple. On the other hand, the above-mentioned bidirectional half-bridge DC-DC converter is applied to the energy storage cabinet. When the DC microgrid system or the photovoltaic storage system is running, the energy storage cabinet can also be directly connected to the high-voltage DC bus without affecting the operation of the entire system, which is convenient for the maintenance, expansion or replacement of the energy storage cabinet.

[0032] In this embodiment, a method for hot-connecting an energy storage cabinet to a DC bus is provided. Figure 3 is a flow chart of a method for hot-connecting an energy storage cabinet to a DC bus according to an embodiment of the present invention. Figure 3 As shown, the process includes the following steps:

[0033] Step S301, after the DC bus positive terminal and the DC bus negative terminal of the energy storage cabinet are connected to the DC bus, the controller controls the first switch K1 to close and the first switch tube Q1 to turn on;

[0034] Step S302, the controller samples the DC bus voltage U1 and the voltage U2 across the capacitor C2, and determines whether the voltage U2 across the capacitor C2 is close to the DC bus voltage U1;

[0035] Step S303, when it is determined that the voltage U2 across the capacitor C2 is close to the DC bus voltage U1, the controller controls the second switch K2 to close, and then controls the first switch K1 and the first switch tube Q1 to open.

[0036] Before the DC bus positive terminal and the DC bus negative terminal of the energy storage cabinet are connected to the DC bus, the first switch K1, the second switch K2, the third switch K3, the fourth switch K4, the fifth switch K5, the first switch tube Q1, and the second switch tube Q2 are controlled to be disconnected.

[0037] Optionally, in this embodiment, when the voltage U2 across the capacitor C2 reaches more than 95% of the DC bus voltage U1, it is considered that the voltage U2 across the capacitor C2 is close to the DC bus voltage U1. Of course, the above judgment condition is not limited to 95% of the DC bus voltage and can be adjusted according to actual measurement results.

[0038] Through the above steps, when the energy storage cabinet is connected to the running high-voltage DC bus, the auxiliary power supply is powered on and the controller is then powered on. The controller outputs a control signal to close the K1 contact and turn on Q1. At this time, Ubus+ forms a path through K1, R1, L1, Q1, C2 to Ubus-, causing the voltage across C2 to rise slowly. The controller synchronously detects the high-voltage DC bus voltage U1 and the voltage across capacitor C2 U2. When the judgment condition is met, that is, the voltage across C2 U2 is greater than 95% of the DC bus voltage U1, the controller outputs a control signal to close K2, and then outputs a control signal to disconnect K1 and Q1 to complete the hot access of the energy storage cabinet. When the energy storage cabinet needs to be turned on, the controller sends a control signal to close K3 and K5. During the entire process of hot access and startup of the energy storage cabinet, the operation of the DC microgrid system or the photovoltaic storage system is not affected.

[0039] In addition, combined Figure 3 The method for hot-connecting an energy storage cabinet to a DC bus in the embodiment of the present invention described above can be implemented by a controller of the energy storage cabinet. Figure 4 A schematic diagram of the hardware structure of a controller of an energy storage cabinet provided in an embodiment of the present invention is shown.

[0040] The controller of the energy storage cabinet may include a processor 41 and a memory 42 storing computer program instructions.

[0041] Specifically, the processor 41 may include a central processing unit (CPU), or an application specific integrated circuit (ASIC), or may be configured to implement one or more integrated circuits of the embodiment of the present invention.

[0042] The memory 42 may include a large capacity memory for data or instructions. For example, but not limitation, the memory 42 may include a hard disk drive (HDD), a floppy disk drive, a flash memory, an optical disk, a magneto-optical disk, a magnetic tape, or a universal serial bus (USB) drive or a combination of two or more of these. In appropriate cases, the memory 42 may include a removable or non-removable (or fixed) medium. In appropriate cases, the memory 42 may be inside or outside the data processing device. In a specific embodiment, the memory 42 is a non-volatile solid-state memory. In a specific embodiment, the memory 42 includes a read-only memory (ROM). In appropriate cases, the ROM may be a mask-programmed ROM, a programmable ROM (PROM), an erasable PROM (EPROM), an electrically erasable PROM (EEPROM), an electrically rewritable ROM (EAROM) or a flash memory or a combination of two or more of these.

[0043] The processor 41 reads and executes computer program instructions stored in the memory 42 to implement any one of the methods for hot-connecting an energy storage cabinet to a DC bus in the above embodiments.

[0044] In one example, the controller of the energy storage cabinet may further include a communication interface 43 and a bus 40. Figure 4 As shown, the processor 41, the memory 42, and the communication interface 43 are connected via a bus 40 and communicate with each other.

[0045] The communication interface 43 is mainly used to implement communication between various modules, devices, units and / or equipment in the embodiment of the present invention.

[0046] The bus 40 includes hardware, software, or both, coupling the components of the controller of the energy storage cabinet to each other. By way of example and not limitation, the bus may include an accelerated graphics port (AGP) or other graphics bus, an enhanced industrial standard architecture (EISA) bus, a front-side bus (FSB), a hypertransport (HT) interconnect, an industrial standard architecture (ISA) bus, an infinite bandwidth interconnect, a low pin count (LPC) bus, a memory bus, a microchannel architecture (MCA) bus, a peripheral component interconnect (PCI) bus, a PCI-Express (PCI-X) bus, a serial advanced technology attachment (SATA) bus, a video electronics standard association local (VLB) bus, or other suitable buses or a combination of two or more of these. Where appropriate, the bus 40 may include one or more buses. Although the embodiments of the present invention describe and illustrate specific buses, the present invention contemplates any suitable bus or interconnect.

[0047] The controller of the energy storage cabinet can execute the method of hot-connecting the energy storage cabinet to the DC bus in the embodiment of the present invention based on the acquired data, thereby realizing the combination Figure 3 The method of hot-connecting the energy storage cabinet to the DC bus is described.

[0048] In addition, in combination with the method of hot-connecting the energy storage cabinet to the DC bus in the above embodiment, the embodiment of the present invention can provide a computer-readable storage medium for implementation. The computer-readable storage medium stores computer program instructions; when the computer program instructions are executed by the processor, any one of the methods of hot-connecting the energy storage cabinet to the DC bus in the above embodiment is implemented.

[0049] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A bidirectional half-bridge DC-DC converter, comprising a first switch tube Q1, a second switch tube Q2 and an inductor L1, characterized in that: The bidirectional half-bridge DC-DC converter further includes: a capacitor C2, a first switch K1, a second switch K2 and a resistor R1, wherein: The source of the first switch tube Q1, the drain of the second switch tube Q2, and one end of the inductor L1 are connected; The other end of the inductor L1, the positive terminal of the battery, and one end of the resistor R1 are connected; The first switch K1 is connected between the other end of the resistor R1 and the positive terminal of the DC bus; The second switch K2 is connected between the drain of the first switch tube and the positive terminal of the DC bus; The negative terminal of the battery, the source of the second switch tube Q2, and the negative terminal of the DC bus are connected; The capacitor C2 is connected between the drain of the first switch tube Q1 and the source of the second switch tube Q2.

2. The bidirectional half-bridge DC-DC converter according to claim 1, characterized in that: The bidirectional half-bridge DC-DC converter further includes: a third switch K3, a fourth switch K4 and a fifth switch K5, wherein: The third switch K3 is connected between the other end of the inductor L1 and the positive terminal of the battery; The fourth switch K4 is connected between the other end of the resistor R1 and the positive terminal of the battery; The fifth switch K5 is connected between the source of the second switch tube Q2 and the negative terminal of the battery.

3. The bidirectional half-bridge DC-DC converter according to claim 2, characterized in that: One or more switches among the first switch K1 , the second switch K2 , the third switch K3 , the fourth switch K4 and the fifth switch K5 are relays or contactors.

4. An energy storage cabinet, comprising: A battery, a controller and an auxiliary power supply, characterized in that the energy storage cabinet also includes a bidirectional half-bridge DC-DC converter as described in any one of claims 1 to 3.

5. The energy storage cabinet according to claim 4, characterized in that: The auxiliary power supply is used to supply power to the controller after taking power from the DC bus.

6. The energy storage cabinet according to claim 4, characterized in that: The controller is used to collect the voltage of the DC bus, collect the voltage across the capacitor C2, and control the on and off of the first switch tube Q1, the first switch K1, the second switch K2, the third switch K3, and the fifth switch K5.

7. A method for hot-connecting an energy storage cabinet to a DC bus as claimed in claim 4, 5 or 6, characterized in that include: After the DC bus positive terminal and the DC bus negative terminal of the energy storage cabinet are connected to the DC bus, the controller controls the first switch K1 to be closed and the first switch tube Q1 to be turned on; The controller samples the DC bus voltage U1 and the voltage U2 across the capacitor C2, and determines whether the voltage U2 across the capacitor C2 is close to the DC bus voltage U1; When it is determined that the voltage U2 across the capacitor C2 is close to the DC bus voltage U1, the controller controls the second switch K2 to be closed, and then controls the first switch K1 and the first switch tube Q1 to be opened.

8. The method for hot-connecting an energy storage cabinet to a DC bus according to claim 7, characterized in that: The method further comprises: Before the DC bus positive terminal and the DC bus negative terminal of the energy storage cabinet are connected to the DC bus, the first switch K1, the second switch K2, the third switch K3, the fourth switch K4, the fifth switch K5, the first switch tube Q1, and the second switch tube Q2 are controlled to be disconnected.

9. A controller for an energy storage cabinet, characterized in that: include: At least one processor, at least one memory and computer program instructions stored in the memory, which implement the method according to claim 7 or 8 when the computer program instructions are executed by the processor.

10. A computer-readable storage medium having computer program instructions stored thereon, characterized in that: When the computer program instructions are executed by a processor, the method according to claim 7 or 8 is implemented.

Images