Direct current charging power supply device

Abstract

The application discloses a direct-current charging power supply device, which comprises a direct-current charging power supply unit for supplying power to an energy storage load, an energy discharge unit for discharging energy of the energy storage load, and a direct-current switch; one end of the direct-current charging power supply unit is connected with one end of the energy storage load through the energy discharge unit, and the other end of the direct-current charging power supply unit is connected with the other end of the energy storage load through the direct-current switch; the direct-current charging power supply unit comprises a plurality of parallelly connected direct-current charging power supply branches, each of the direct-current charging power supply branches comprises a cascade unit and a reactor which are connected in series, and the cascade unit comprises a plurality of cascaded power units. The direct-current charging power supply device provided by the application is composed of a plurality of cascaded power units, so that the problem of large output voltage ripple and poor precision of a high-power high-voltage direct-current system is avoided, subsequent module assembly is facilitated, and the maintenance difficulty is reduced.

Description

Technical Field

[0001] This application relates to the field of energy storage technology, and in particular to a DC charging power supply device. Background Technology

[0002] With the continuous construction of modern power grids, the scale of new energy power generation is gradually expanding and the development of distributed generation technology is growing stronger, the importance of power storage is becoming increasingly apparent.

[0003] Magnet energy storage systems have high energy density, fast response speed, and can release a large amount of power in a short time, making them a typical power-type energy storage system. They offer advantages such as high energy density, zero loss, large energy output, flexible use, convenient control, and high conversion efficiency.

[0004] Currently, there are many types of high-voltage, high-power AC systems, but DC systems are limited by application scenarios and technical means, with fewer types available for high-power, especially high-voltage, DC systems. To reduce output DC voltage ripple and improve output DC voltage accuracy, the main solutions are to increase the transistor switching frequency and the inductance of the output reactor. However, transistors with higher switching frequencies cannot be used in high-power, high-voltage systems. Reactors with larger inductances not only significantly increase operating costs but also have greater losses and larger size, making them difficult to install and use, and resulting in higher subsequent maintenance costs. Utility Model Content

[0005] This application provides a DC charging power supply device to solve the problems of large output voltage ripple, poor accuracy, and high difficulty in subsequent module assembly and maintenance of high-power, high-voltage DC systems.

[0006] This application provides a DC charging power supply device, including a DC charging power supply unit for supplying power to an energy storage load, an energy discharge unit for discharging energy from the energy storage load, and a DC switch;

[0007] One end of the DC charging power supply unit is connected to one end of the energy storage load through the energy discharge unit, and the other end of the DC charging power supply unit is connected to the other end of the energy storage load through the DC switch;

[0008] The DC charging power supply unit includes multiple DC charging power supply branches connected in parallel. Each DC charging power supply branch includes cascaded units and reactors connected in series. Each cascaded unit includes multiple cascaded power units.

[0009] In one example, the energy dissipation unit includes a first discharge resistor and a discharge switch connected in parallel.

[0010] In one example, the discharge switch includes a DC circuit breaker and the DC circuit breaker is a normally closed switch.

[0011] In one example, the power unit includes a bus energy storage module, an energy braking module, and a power conversion module connected in sequence.

[0012] In one example, the bus energy storage module includes a first capacitor, a second capacitor, and a fuse, wherein the first capacitor and the second capacitor are connected in parallel and then connected in series with the fuse.

[0013] In one example, the first capacitor or the second capacitor includes a supercapacitor or a thin-film capacitor.

[0014] In one example, the energy braking module includes a second discharge resistor, a first transistor, and a second transistor, wherein the first transistor and the second transistor are connected in series, and the second discharge resistor is connected in parallel with the first transistor.

[0015] In one example, the first transistor or the second transistor includes at least one of MOSFET, IGBT, and IGCT.

[0016] In one example, the power conversion module includes a third transistor and a fourth transistor connected in series.

[0017] In one example, the third transistor or the fourth transistor includes at least one of MOSFET, IGBT, and IGCT.

[0018] The DC charging power supply device provided in this application constitutes a high-power DC charging power supply device through multiple cascaded power units, which avoids the problems of large output voltage ripple and poor accuracy of high-power high-voltage DC systems, facilitates subsequent module assembly, and reduces maintenance difficulty. Attached Figure Description

[0019] Figure 1 A schematic diagram of a DC charging power supply device provided in an embodiment of this application;

[0020] Figure 2 This is a schematic diagram of a DC charging power supply branch provided in an embodiment of this application;

[0021] Figure 3 A schematic diagram of a power unit provided in an embodiment of this application;

[0022] Figure 4 This is a schematic diagram of the current flow direction of the DC charging power supply device provided in the embodiments of this application in charging mode;

[0023] Figure 5 A schematic diagram of the current flow direction of the DC charging power supply device in sustain mode provided in the embodiments of this application;

[0024] Figure 6This is a schematic diagram of the current flow direction of the DC charging power supply device provided in the embodiment of this application in the discharge mode.

[0025] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0026] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer and more understandable, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of this application and are not intended to limit the scope of this application.

[0027] In the description of this application, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0028] like Figures 1-3 As shown, this application provides a DC charging power supply device, including a DC charging power supply unit Q1 for supplying power to an energy storage load, an energy discharge unit Q2 for discharging energy from the energy storage load, and a DC switch Q3.

[0029] One end of the DC charging power supply unit Q1 is connected to one end of the energy storage load through the energy discharge unit Q2, and the other end of the DC charging power supply unit Q1 is connected to the other end of the energy storage load through the DC switch Q3.

[0030] The DC charging power supply unit Q1 includes multiple DC charging power supply branches Q10 connected in parallel. Each DC charging power supply branch Q10 includes a cascaded unit Q100 and a reactor Q101 connected in series. Each cascaded unit Q100 includes multiple cascaded power units Q102.

[0031] In some examples, the energy discharge unit Q2 includes a first discharge resistor Q21 and a discharge switch Q22 connected in parallel. The discharge switch Q22 includes a DC circuit breaker, and the DC circuit breaker is a normally closed switch.

[0032] In some examples, the power unit Q102 includes a bus energy storage module Q1021, an energy braking module Q1022, and a power conversion module Q1023 connected in sequence. The bus energy storage module Q1021 and the energy braking module Q1022 are connected to the DC side of the power conversion module Q1023.

[0033] In some examples, the bus energy storage module Q1021 includes a first capacitor C1, a second capacitor C2, and a fuse Z1. The first capacitor C1 and the second capacitor C2 are connected in parallel and then connected in series with the fuse Z1. The first capacitor C1 or the second capacitor C2 may be a supercapacitor or a thin-film capacitor.

[0034] It should be noted that the bus energy storage module Q1021 can adopt an independent bus structure (as shown by BUS+ and BUS- in the figure), or it can share the same bus with other bus energy storage modules Q1021.

[0035] In some examples, the energy braking module Q1022 includes a second discharge resistor R2, a first transistor S1, and a second transistor S2. The first transistor S1 and the second transistor S2 are connected in series, and the second discharge resistor R2 is connected in parallel with the first transistor S1. The first transistor S1 or the second transistor S2 includes at least one of a MOSFET, an IGBT, and an IGCT.

[0036] In some examples, the power conversion module Q1023 includes a third transistor S3 and a fourth transistor S4 connected in series. The third transistor S3 or the fourth transistor S4 includes at least one of a MOSFET, an IGBT, and an IGCT. The connection point of the third transistor S3 and the fourth transistor S4 is cascaded with other power units Q102.

[0037] The DC charging power supply device has three operating modes: charging mode, sustaining mode, and discharging mode.

[0038] like Figure 4 As shown, in charging mode, the bus energy storage module Q1021 is charged by the DC charging power supply device. The red arrow in the figure indicates the current flow direction.

[0039] like Figure 5 As shown, in the maintenance mode of the DC charging power supply device, the power required in the maintenance mode is much less than that in the charging mode. The number of power units Q102 put into operation is determined according to the required power. The power units Q102 are put into operation in turn to maintain the bus voltage balance among the power units Q102. The green arrow in the figure shows the current flow direction.

[0040] like Figure 6 As shown, in the discharge mode of the DC charging power supply device, the discharge switch Q22 in the energy discharge unit Q2 is disconnected, and the current flows through the first discharge resistor Q21, that is, the energy storage load discharges through the first discharge resistor Q21; in the event of a fault, it also discharges in this way; the blue arrow in the figure shows the direction of current flow.

[0041] The preferred embodiments of this application have been described above with reference to the accompanying drawings, but this does not limit the scope of the claims. Any modifications, equivalent substitutions, and improvements made by those skilled in the art without departing from the scope and spirit of this application shall be within the scope of the claims.

Claims

1. A DC charging power supply device, characterized in that, The DC charging power supply device includes a DC charging power supply unit for supplying power to the energy storage load, an energy discharge unit for discharging energy from the energy storage load, and a DC switch. One end of the DC charging power supply unit is connected to one end of the energy storage load through the energy discharge unit, and the other end of the DC charging power supply unit is connected to the other end of the energy storage load through the DC switch; The DC charging power supply unit includes multiple DC charging power supply branches connected in parallel. Each DC charging power supply branch includes cascaded units and reactors connected in series. Each cascaded unit includes multiple cascaded power units.

2. The DC charging power supply device according to claim 1, characterized in that, The energy discharge unit includes a first discharge resistor and a discharge switch connected in parallel.

3. The DC charging power supply device according to claim 2, characterized in that, The discharge switch includes a DC circuit breaker, and the DC circuit breaker is a normally closed switch.

4. The DC charging power supply device according to claim 1, characterized in that, The power unit includes a bus energy storage module, an energy braking module, and a power conversion module connected in sequence.

5. The DC charging power supply device according to claim 4, characterized in that, The bus energy storage module includes a first capacitor, a second capacitor, and a fuse. The first capacitor and the second capacitor are connected in parallel and then connected in series with the fuse.

6. The DC charging power supply device according to claim 5, characterized in that, The first capacitor or the second capacitor includes a supercapacitor or a thin-film capacitor.

7. The DC charging power supply device according to claim 4, characterized in that, The energy braking module includes a second discharge resistor, a first transistor, and a second transistor. The first transistor and the second transistor are connected in series, and the second discharge resistor is connected in parallel with the first transistor.

8. The DC charging power supply device according to claim 7, characterized in that, The first transistor or the second transistor includes at least one of MOSFET, IGBT, and IGCT.

9. The DC charging power supply device according to claim 4, characterized in that, The power conversion module includes a third transistor and a fourth transistor connected in series.

10. The DC charging power supply device according to claim 9, characterized in that, The third transistor or the fourth transistor includes at least one of MOSFET, IGBT, and IGCT.

Images