Electric energy conversion device and photovoltaic storage and charging integrated DC power distribution system

Abstract

The invention relates to the technical field of direct current power distribution, and discloses an electric energy conversion device and an optical storage and charging integrated direct current power distribution system, the electric energy conversion device is applied to the optical storage and charging integrated direct current power distribution system, and the electric energy conversion device comprises a bidirectional DC / DC conversion circuit and a DSP control circuit; the DSP control circuit is used for acquiring voltage and current information of a high-voltage direct-current bus and a low-voltage direct-current bus in the direct-current power distribution system, processing and analyzing the voltage and current information, and adjusting a PWM (Pulse-Width Modulation) driving signal according to a processing and analyzing result to control the power transmission state of the bidirectional DC / DC conversion circuit; and the bidirectional DC / DC conversion circuit is used for carrying out conversion between high-voltage direct current and low-voltage direct current according to the PWM driving signal. The electric energy conversion device can realize bidirectional flow of direct-current electric energy, can supply power to a power grid from a power distribution system, and also can charge the power distribution system from the power grid. Bidirectional control enables the system to be more flexible and reliable, and the energy management effect is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of direct current power distribution, and in particular to an electric energy conversion device and a photovoltaic storage and charging integrated direct current power distribution system. Background Art

[0002] With the continuous advancement of the construction of new power systems, more and more new energy sources are gradually entering people's daily lives. In many scenarios such as new energy vehicle charging and swapping stations, highway service areas, urban central commercial complexes and public parking lots, industrial parks, as well as household and commercial users, the integrated photovoltaic storage and charging system has shown great application potential.

[0003] At present, with the continuous advancement of the construction of zero-carbon power supply stations, the integrated photovoltaic storage and charging DC distribution system consisting of photovoltaic power generation components, energy storage components and charging pile components is being continuously promoted in power supply stations and other power institutions. The basic stage of the photovoltaic storage and charging integration industry has basically matured, and the supporting facilities are becoming more complete. In the current photovoltaic storage and charging integration system, the load and DC charging pile are directly connected to the DC bus and powered by DC. Although this power supply method reduces the loss of electric energy compared to the traditional photovoltaic AC distribution solution, due to the volatility and instability of photovoltaic power generation itself, unstable power output may occur when supplying power to DC loads. Summary of the invention

[0004] In view of the problem that the power output may be unstable when the integrated photovoltaic storage and charging system in the prior art supplies power to DC loads and DC charging piles, the present invention provides an electric energy conversion device and an integrated photovoltaic storage and charging DC power distribution system, which can ensure the stable operation of DC loads and DC charging piles when the distributed solar power generation is insufficient or unstable. The specific technical solution is as follows:

[0005] An electric energy conversion device is applied to a photovoltaic storage and charging integrated DC power distribution system, comprising a bidirectional DC / DC conversion circuit and a DSP control circuit;

[0006] The DSP control circuit is used to obtain the voltage and current information of the high-voltage DC bus and the low-voltage DC bus in the DC power distribution system, and process and analyze them, and adjust the PWM drive signal according to the processing and analysis results to control the power transmission state of the bidirectional DC / DC conversion circuit;

[0007] The bidirectional DC / DC conversion circuit is used for converting between high voltage direct current and low voltage direct current according to the PWM drive signal.

[0008] Preferably, the bidirectional DC / DC conversion circuit includes a high voltage input terminal E1, a low voltage input terminal E2, a capacitor C1, a switch tube Q1, a switch tube Q2, a switch tube Q3, a switch tube Q4, a switch tube Q5, a switch tube Q6, a switch tube Q7, a switch tube Q8, a capacitor C2, a DC blocking capacitor C3, a filter inductor L1, a filter inductor L2 and a high frequency isolation transformer T;

[0009] One end of the high-voltage input terminal E1 is respectively connected to one end of the capacitor C1, one end of the switch tube Q1 and one end of the switch tube Q3; the other end of the high-voltage input terminal E1 is respectively connected to the other end of the capacitor C1, one end of the switch tube Q2 and one end of the switch tube Q4; the other end of the switch tube Q1 is respectively connected to one end of the filter inductor L1 and the other end of the switch tube Q2; the other end of the filter inductor L1 is connected to the DC blocking capacitor C3 and then to the positive input end of the high-frequency isolation transformer T; the other end of the switch tube Q3 is respectively connected to the other end of the switch tube Q4 and the negative input end of the high-frequency isolation transformer T;

[0010] One end of the low-voltage input terminal E2 is respectively connected to one end of the capacitor C2, one end of the switch tube Q5 and one end of the switch tube Q7; the other end of the low-voltage input terminal E2 is respectively connected to the other end of the capacitor C2, one end of the switch tube Q6 and one end of the switch tube Q8; the other end of the switch tube Q7 is respectively connected to one end of the filter inductor L2 and the other end of the switch tube Q8; the other end of the filter inductor L2 is connected to the positive output end of the high-frequency isolation transformer T; the other end of the switch tube Q5 is respectively connected to the other end of the switch tube Q6 and the negative input end of the high-frequency isolation transformer T.

[0011] Preferably, the DSP control circuit includes a DSP chip, a crystal oscillator Y1, a capacitor C4, a capacitor C5, a capacitor C6, a first voltage sampling interface Ui, a second voltage sampling interface Uo, a first current sampling interface Ii and a second current sampling interface Io;

[0012] The first voltage sampling interface Ui and the second voltage sampling interface Uo are connected to one end of the capacitor C4; the other end of the capacitor C4 is connected to the DSP chip and one end of the crystal oscillator Y1; the first current sampling interface Ii and the second current sampling interface Io are connected to one end of the capacitor C5; the other end of the capacitor C5 is connected to the DSP chip and the other end of the crystal oscillator Y1; the pins PWM1, PWM2, PWM3, PWM4, PWM5, PWM6, PWM7 and PWM8 of the DSP chip are respectively connected to the switch tube Q1, switch tube Q2, switch tube Q3, switch tube Q4, switch tube Q5, switch tube Q6, switch tube Q7 and switch tube Q8; one end of the capacitor C6 is connected to the DSP chip, and the other end is connected to the ground.

[0013] A photovoltaic storage and charging integrated DC power distribution system, comprising a public power grid, an AC / DC conversion device, a high-voltage DC bus, a low-voltage DC bus, a photovoltaic module, a photovoltaic converter, an energy storage module, an energy storage converter, a DC load, a DC charging pile and the aforementioned electric energy conversion device; the photovoltaic module is connected to the photovoltaic converter and then connected to the low-voltage DC bus; the low-voltage DC bus is respectively connected to a DC charging pile, a DC load, one end of the energy storage converter and one end of the electric energy conversion device; the other end of the energy storage converter is connected to the energy storage module; the other end of the electric energy conversion device is connected to the high-voltage DC bus, and the high-voltage DC bus is connected to the public power grid through the AC / DC conversion device;

[0014] The electric energy conversion device is used to: when the electric energy required by the DC load and the DC charging pile is less than the electric energy provided by the photovoltaic components and the energy storage components, the excess electric energy is boosted from the low-voltage DC bus to the high-voltage DC bus and then transmitted to the public power grid; when the electric energy required by the DC load and the DC charging pile is more than the electric energy provided by the photovoltaic components and the energy storage components, the electric energy is obtained from the public power grid through the high-voltage DC bus, and the electric energy is stepped down to the low-voltage DC bus to power the DC load and the DC charging pile.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] 1. The electric energy conversion device of the present application can realize the bidirectional flow of DC electric energy. When the electric energy conversion device is connected to the DC distribution network, it can supply power from the distribution system to the grid, and can also charge the distribution system from the grid. This bidirectional control capability improves the flexibility and reliability of the system and makes energy management more efficient.

[0017] 2. A photovoltaic storage and charging integrated DC distribution system of the present invention connects an electric energy conversion device between a high-voltage DC bus and a low-voltage DC bus. The electric energy conversion device can realize a bidirectional flow of DC electric energy, and can supply power from the distribution system to the power grid, and can also charge the distribution system from the power grid. When the electric energy required by the DC load and the DC charging pile is less than the electric energy provided by the photovoltaic components and the energy storage components, the electric energy conversion device boosts the excess electric energy from the low-voltage DC bus to the high-voltage DC bus, and then transmits it to the public power grid; when the electric energy required by the DC load and the DC charging pile is more than the electric energy provided by the photovoltaic components and the energy storage components, the electric energy conversion device obtains electric energy from the high-voltage DC bus and steps it down to the low-voltage DC bus, and then supplies it to the DC load and the DC charging pile. The present invention ensures the stable operation of the DC load and the DC charging pile through the electric energy conversion device when the distributed solar power generation is insufficient or unstable, and improves the flexibility and reliability of the photovoltaic storage and charging integrated DC distribution system through a bidirectional control method, making energy management more efficient. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following is a brief introduction to the drawings required for the specific embodiments or the description of the prior art. In all the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the elements or parts are not necessarily drawn according to the actual scale.

[0019] Figure 1 The schematic diagram of the electric energy conversion device of the present invention is as follows

[0020] Figure 2 The bidirectional DC / DC conversion circuit schematic diagram of the electric energy conversion device of the present invention.

[0021] Figure 3 The figure is a schematic diagram of the DSP control circuit of the electric energy conversion device of the present invention.

[0022] Figure 4 This is a topology schematic diagram of a photovoltaic storage and charging integrated DC power distribution system of the present invention.

[0023] Figure 5 It is a schematic diagram of the control flow of the electric energy conversion device of the present invention. DETAILED DESCRIPTION

[0024] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] It should be understood that when used in this specification and the appended claims, the terms "include" and "comprises" indicate the presence of described features, integers, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or combinations thereof.

[0026] It should also be understood that the terms used in the present specification are only for the purpose of describing specific embodiments and are not intended to limit the present invention. As used in the present specification and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to include plural forms.

[0027] It should be further understood that the term "and / or" used in the present description and the appended claims refers to any and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0028] See the following examples Figures 1 to 5 .

[0029] The embodiment of the present application provides an electric energy conversion device, which is applied to a photovoltaic storage and charging integrated DC power distribution system, including a bidirectional DC / DC conversion circuit and a DSP control circuit;

[0030] The DSP control circuit is used to obtain the voltage and current information of the high-voltage DC bus and the low-voltage DC bus in the DC power distribution system, and process and analyze them, and adjust the PWM drive signal according to the processing and analysis results to control the power transmission state of the bidirectional DC / DC conversion circuit;

[0031] The bidirectional DC / DC conversion circuit is used for converting between high voltage direct current and low voltage direct current according to the PWM drive signal.

[0032] It should be noted that the electric energy conversion device also includes a drive circuit, which is used to amplify the PWM drive signal of the DSP control circuit to drive the switch tube of the bidirectional DC / DC conversion circuit to achieve conversion between high-voltage DC and low-voltage DC. Since the drive circuit is a signal amplification circuit, it is a conventional signal amplification method and is not described in detail here.

[0033] The electric energy conversion device of the present application obtains the voltage and current information of the high-voltage DC bus and the low-voltage DC bus in the DC power distribution system through the DSP control circuit, and amplifies the PWM drive signal to drive the switch tube of the bidirectional DC / DC conversion circuit, realizing the conversion between high-voltage DC and low-voltage DC, and realizing the bidirectional flow of DC power. The electric energy conversion device is connected to the DC distribution network, and it can supply power from the distribution system to the power grid, and it can also charge the distribution system from the power grid. This bidirectional control capability improves the flexibility and reliability of the system and makes energy management more efficient.

[0034] Specifically, the bidirectional DC / DC conversion circuit includes a high voltage input terminal E1, a low voltage input terminal E2, a capacitor C1, a switch tube Q1, a switch tube Q2, a switch tube Q3, a switch tube Q4, a switch tube Q5, a switch tube Q6, a switch tube Q7, a switch tube Q8, a capacitor C2, a DC blocking capacitor C3, a filter inductor L1, a filter inductor L2 and a high frequency isolation transformer T;

[0035] One end of the high-voltage input terminal E1 is respectively connected to one end of the capacitor C1, one end of the switch tube Q1 and one end of the switch tube Q3; the other end of the high-voltage input terminal E1 is respectively connected to the other end of the capacitor C1, one end of the switch tube Q2 and one end of the switch tube Q4; the other end of the switch tube Q1 is respectively connected to one end of the filter inductor L1 and the other end of the switch tube Q2; the other end of the filter inductor L1 is connected to the DC blocking capacitor C3 and then to the positive input end of the high-frequency isolation transformer T; the other end of the switch tube Q3 is respectively connected to the other end of the switch tube Q4 and the negative input end of the high-frequency isolation transformer T;

[0036] One end of the low-voltage input terminal E2 is respectively connected to one end of the capacitor C2, one end of the switch tube Q5 and one end of the switch tube Q7; the other end of the low-voltage input terminal E2 is respectively connected to the other end of the capacitor C2, one end of the switch tube Q6 and one end of the switch tube Q8; the other end of the switch tube Q7 is respectively connected to one end of the filter inductor L2 and the other end of the switch tube Q8; the other end of the filter inductor L2 is connected to the positive output end of the high-frequency isolation transformer T; the other end of the switch tube Q5 is respectively connected to the other end of the switch tube Q6 and the negative input end of the high-frequency isolation transformer T.

[0037] In this embodiment, the high-voltage input terminal E1 is the input terminal of the high-voltage DC bus, providing high-voltage DC power; the low-voltage input terminal E2 is the input terminal of the low-voltage DC bus, providing low-voltage DC power. Capacitor C1 is a high-voltage side filter capacitor, used to smooth the voltage fluctuations on the high-voltage DC bus; capacitor C2 is a low-voltage side filter capacitor, used to smooth the voltage fluctuations on the low-voltage DC bus. Switch tubes Q1, Q2, Q3 and Q4 are high-voltage side switch tubes, which realize the conversion of high-voltage DC power to AC power through precise control; switch tubes Q5, Q6, Q7 and Q8 are low-voltage side switch tubes, which also realize the conversion of low-voltage DC power to AC power. The DC isolation capacitor C3 is used to isolate the DC component to ensure that the high-frequency isolation transformer T only transmits AC power. The high-frequency isolation transformer T is used to achieve electrical isolation and voltage conversion, and transmit AC power at the same time. Filter inductor L1 and filter inductor L2 are used to smooth the output voltage waveform.

[0038] Specifically, the DSP control circuit includes a DSP chip, a crystal oscillator Y1, a capacitor C4, a capacitor C5, a capacitor C6, a first voltage sampling interface Ui, a second voltage sampling interface Uo, a first current sampling interface Ii and a second current sampling interface Io;

[0039] The first voltage sampling interface Ui and the second voltage sampling interface Uo are connected to one end of the capacitor C4; the other end of the capacitor C4 is connected to the DSP chip and one end of the crystal oscillator Y1; the first current sampling interface Ii and the second current sampling interface Io are connected to one end of the capacitor C5; the other end of the capacitor C5 is connected to the DSP chip and the other end of the crystal oscillator Y1; the pins PWM1, PWM2, PWM3, PWM4, PWM5, PWM6, PWM7 and PWM8 of the DSP chip are respectively connected to the switch tube Q1, switch tube Q2, switch tube Q3, switch tube Q4, switch tube Q5, switch tube Q6, switch tube Q7 and switch tube Q8; one end of the capacitor C6 is connected to the DSP chip, and the other end is connected to the ground.

[0040] In the specific implementation, the first voltage sampling interface Ui on the high-voltage DC bus side is sent to the AN0 port, the second voltage sampling interface Uo on the low-voltage DC bus side is sent to the AN1 port, the first current sampling interface Ii on the high-voltage DC bus side is sent to the AN2 port, and the second current sampling interface Io on the low-voltage DC bus side is sent to the AN3 port. The crystal oscillator Y1 provides a stable clock signal for the DSP chip. Capacitors C4 and C5 are used to stabilize the oscillation frequency of the crystal oscillator. The DSP chip uses TMS320LF2407, which is responsible for receiving sampling signals, generating PWM drive signals, etc. Capacitor C6 is used to smooth the power supply voltage of the DSP chip to ensure the stable operation of the DSP chip.

[0041] The DSP control circuit samples the voltage and current information of the high-voltage DC bus and the low-voltage DC bus, and processes them. According to the sampled information, the DSP chip adjusts the duty cycle and frequency of the PWM drive signal to achieve precise control of the output voltage and current. The DSP chip generates 8 PWM drive signals according to the preset algorithm and sampled information. The 8 PWM drive signals control the 8 switch tubes (switch tube Q1, switch tube Q2, switch tube Q3, switch tube Q4, switch tube Q5, switch tube Q6, switch tube Q7 and switch tube Q8) on the high-voltage side and the low-voltage side respectively. The DSP control circuit realizes precise control of the bidirectional DC / DC conversion circuit, realizes voltage conversion, and provides stable output voltage and current.

[0042] The electric energy conversion device of the present application can realize the bidirectional flow of DC electric energy. When the electric energy conversion device is connected to the DC distribution network, it can supply power from the distribution system to the grid, and can also charge the distribution system from the grid. This bidirectional control capability improves the flexibility and reliability of the system and makes energy management more efficient.

[0043] The embodiment of the present application also provides a photovoltaic storage and charging integrated DC power distribution system, including a public power grid, an AC / DC conversion device, a high-voltage DC bus, a low-voltage DC bus, a photovoltaic module, a photovoltaic converter, an energy storage module, an energy storage converter, a DC load, a DC charging pile and an electric energy conversion device; the photovoltaic module is connected to the photovoltaic converter and then connected to the low-voltage DC bus; the low-voltage DC bus is respectively connected to a DC charging pile, a DC load, one end of the energy storage converter and one end of the electric energy conversion device; the other end of the energy storage converter is connected to the energy storage module; the other end of the electric energy conversion device is connected to the high-voltage DC bus, and the high-voltage DC bus is connected to the public power grid through the AC / DC conversion device;

[0044] The electric energy conversion device is used to: when the electric energy required by the DC load and the DC charging pile is less than the electric energy provided by the photovoltaic components and the energy storage components, the excess electric energy is boosted from the low-voltage DC bus to the high-voltage DC bus and then transmitted to the public power grid; when the electric energy required by the DC load and the DC charging pile is more than the electric energy provided by the photovoltaic components and the energy storage components, the electric energy is obtained from the public power grid through the high-voltage DC bus, and the electric energy is stepped down to the low-voltage DC bus to power the DC load and the DC charging pile.

[0045] In this embodiment, the AC / DC conversion device serves as the interface between the system and the AC power grid, converting AC power into DC power to provide basic power for the system. The photovoltaic converter is directly connected to the photovoltaic module, converting solar energy into DC power, and providing power for the DC charging pile and DC load on the DC bus; the energy storage converter is connected to the energy storage module, responsible for releasing the stored power when solar power generation is insufficient, or storing excess power when power generation is excessive.

[0046] The electric energy conversion device is connected to the high-voltage DC bus and the low-voltage DC bus, and adjusts the working mode according to the different output powers of the photovoltaic module and the energy storage module:

[0047] (1) Boost mode: When the power required by the DC load and DC charging pile is less than the power provided by the PV panels and energy storage components, the power conversion device boosts the excess power from the low-voltage DC bus to the high-voltage DC bus and then transmits it to the public grid.

[0048] Step-down mode: When the electric energy required by the DC load and DC charging pile exceeds the electric energy provided by the photovoltaic components and energy storage components, the electric energy conversion device obtains electric energy from the high-voltage DC bus and steps it down to the low-voltage DC bus, and then supplies it to the DC load and DC charging pile.

[0049] The present invention provides a photovoltaic storage and charging integrated DC power distribution system by connecting an electric energy conversion device between a high-voltage DC bus and a low-voltage DC bus. The electric energy conversion device can realize the bidirectional flow of DC power, and can supply power from the distribution system to the power grid, and can also charge the distribution system from the power grid. When the power required by the DC load and the DC charging pile is less than the power provided by the photovoltaic components and the energy storage components, the electric energy conversion device boosts the excess power from the low-voltage DC bus to the high-voltage DC bus, and then transmits it to the public power grid; when the power required by the DC load and the DC charging pile is more than the power provided by the photovoltaic components and the energy storage components, the electric energy conversion device obtains power from the high-voltage DC bus and steps it down to the low-voltage DC bus, and then supplies it to the DC load and the DC charging pile. The present invention ensures the stable operation of the DC load and the DC charging pile through the electric energy conversion device when the distributed solar power generation is insufficient or unstable, and improves the flexibility and reliability of the photovoltaic storage and charging integrated DC power distribution system through a bidirectional control method, making energy management more efficient. The advanced topology structure and control strategy are adopted to achieve high-efficiency energy conversion and reduce energy loss during transmission. At the same time, the power flow and size can be automatically adjusted according to grid demand and the status of photovoltaic storage components. Intelligent power management can optimize system operation, achieve supply and demand balance, and improve the overall performance of the system.

[0050] It should be noted that if Figure 4 This is the control flow chart of the electric energy conversion device. The main program flow of the electric energy conversion device starts with system initialization to ensure that all hardware components and system parameters are set correctly; then the device samples to obtain key parameters such as input voltage and current. Based on the sampled data, the device determines the current working mode and decides whether to enable the boost mode or the buck mode; after completing the corresponding voltage regulation, the device will enter a waiting state and wait for the next sampling cycle.

[0051] Those of ordinary skill in the art will appreciate that the units of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the composition of each example has been generally described in terms of function in the above description. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.

[0052] In the embodiments provided by the present invention, it should be understood that the division of units is only a logical function division, and there may be other division methods in actual implementation, for example, multiple units can be combined into one unit, one unit can be split into multiple units, or some features can be ignored, etc.

[0053] In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of software functional units.

[0054] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution can be embodied in the form of a software product, which is stored in a storage medium and includes several instructions for a computer device (which can be a personal computer, a server or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, read-only memory (ROM, Read-0nlyMemory), random access memory (RAM, RandomAccessMemory), mobile hard disk, magnetic disk or optical disk, etc., which can store program code.

[0055] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. These modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be included in the scope of the claims and specification of the present invention.

Claims

1. An electric energy conversion device, applied to a photovoltaic storage and charging integrated DC power distribution system, characterized in that: Including bidirectional DC / DC conversion circuit and DSP control circuit; The DSP control circuit is used to obtain the voltage and current information of the high-voltage DC bus and the low-voltage DC bus in the DC power distribution system, and process and analyze them, and adjust the PWM drive signal according to the processing and analysis results to control the power transmission state of the bidirectional DC / DC conversion circuit; The bidirectional DC / DC conversion circuit is used for converting between high voltage direct current and low voltage direct current according to the PWM drive signal.

2. The electric energy conversion device according to claim 1, characterized in that: The bidirectional DC / DC conversion circuit includes a high voltage input terminal E1, a low voltage input terminal E2, a capacitor C1, a switch tube Q1, a switch tube Q2, a switch tube Q3, a switch tube Q4, a switch tube Q5, a switch tube Q6, a switch tube Q7, a switch tube Q8, a capacitor C2, a DC blocking capacitor C3, a filter inductor L1, a filter inductor L2 and a high frequency isolation transformer T; One end of the high-voltage input terminal E1 is respectively connected to one end of the capacitor C1, one end of the switch tube Q1 and one end of the switch tube Q3; the other end of the high-voltage input terminal E1 is respectively connected to the other end of the capacitor C1, one end of the switch tube Q2 and one end of the switch tube Q4; the other end of the switch tube Q1 is respectively connected to one end of the filter inductor L1 and the other end of the switch tube Q2; the other end of the filter inductor L1 is connected to the DC blocking capacitor C3 and then to the positive input end of the high-frequency isolation transformer T; the other end of the switch tube Q3 is respectively connected to the other end of the switch tube Q4 and the negative input end of the high-frequency isolation transformer T; One end of the low-voltage input terminal E2 is respectively connected to one end of the capacitor C2, one end of the switch tube Q5 and one end of the switch tube Q7; the other end of the low-voltage input terminal E2 is respectively connected to the other end of the capacitor C2, one end of the switch tube Q6 and one end of the switch tube Q8; the other end of the switch tube Q7 is respectively connected to one end of the filter inductor L2 and the other end of the switch tube Q8; the other end of the filter inductor L2 is connected to the positive output end of the high-frequency isolation transformer T; the other end of the switch tube Q5 is respectively connected to the other end of the switch tube Q6 and the negative input end of the high-frequency isolation transformer T.

3. The electric energy conversion device according to claim 2, characterized in that: The DSP control circuit includes a DSP chip, a crystal oscillator Y1, a capacitor C4, a capacitor C5, a capacitor C6, a first voltage sampling interface Ui, a second voltage sampling interface Uo, a first current sampling interface Ii and a second current sampling interface Io; The first voltage sampling interface Ui and the second voltage sampling interface Uo are connected to one end of the capacitor C4; the other end of the capacitor C4 is connected to the DSP chip and one end of the crystal oscillator Y1; the first current sampling interface Ii and the second current sampling interface Io are connected to one end of the capacitor C5; the other end of the capacitor C5 is connected to the DSP chip and the other end of the crystal oscillator Y1; the pins PWM1, PWM2, PWM3, PWM4, PWM5, PWM6, PWM7 and PWM8 of the DSP chip are respectively connected to the switch tube Q1, switch tube Q2, switch tube Q3, switch tube Q4, switch tube Q5, switch tube Q6, switch tube Q7 and switch tube Q8; one end of the capacitor C6 is connected to the DSP chip, and the other end is connected to the ground.

4. A photovoltaic storage and charging integrated DC power distribution system, comprising a public power grid, an AC / DC conversion device, a high-voltage DC bus, a low-voltage DC bus, a photovoltaic module, a photovoltaic converter, an energy storage module, an energy storage converter, a DC load, and a DC charging pile, characterized in that: It also includes the electric energy conversion device according to any one of claims 1 to 3; the photovoltaic component is connected to the photovoltaic converter and then connected to the low-voltage DC bus; the low-voltage DC bus is respectively connected to a DC charging pile, a DC load, one end of the energy storage converter and one end of the electric energy conversion device; the other end of the energy storage converter is connected to the energy storage component; the other end of the electric energy conversion device is connected to the high-voltage DC bus, and the high-voltage DC bus is connected to the public power grid through the AC / DC conversion device; The electric energy conversion device is used to: when the electric energy required by the DC load and the DC charging pile is less than the electric energy provided by the photovoltaic components and the energy storage components, the excess electric energy is boosted from the low-voltage DC bus to the high-voltage DC bus and then transmitted to the public power grid; when the electric energy required by the DC load and the DC charging pile is more than the electric energy provided by the photovoltaic components and the energy storage components, the electric energy is obtained from the public power grid through the high-voltage DC bus, and the electric energy is stepped down to the low-voltage DC bus to power the DC load and the DC charging pile.

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