A black start and power on / off circuit for a photovoltaic storage and charging integrated device

Abstract

This invention proposes a black start and power-on / off circuit for an integrated photovoltaic-energy storage-charging system. The system includes a photovoltaic device, an energy storage device, a grid connection device, a control device, and a bus capacitor. The bus capacitor is connected to the photovoltaic device, the energy storage device, and the grid connection device simultaneously. The energy storage device includes a DC-DC converter module and a battery switch module. The DC-DC converter module includes an input capacitor, a first switching transistor and a first diode connected in parallel, a second switching transistor and a second diode connected in parallel. The first terminal of the input capacitor is connected to the battery switch module, and the common connection point of the first and second switching transistors is connected to the first terminal of the input capacitor. The battery switch module includes a start switch. The control device includes a main controller. When the photovoltaic device is operating and the AC grid is de-energized, the main controller controls the photovoltaic device to charge the bus capacitor. After the bus capacitor is fully charged, it controls the second switching transistor to conduct to charge the input capacitor. After the input capacitor is fully charged, it controls the start switch to close.

Description

Technical Field

[0001] This invention relates to the field of power electronics technology, and in particular to a black start and power-on / off circuit for an integrated photovoltaic, energy storage and charging unit. Background Art

[0002] A photovoltaic-storage-charging integrated unit is a comprehensive device that integrates photovoltaic power generation, energy storage, and charging functions, and is mainly used in smart grids and microgrids. Existing photovoltaic-storage-charging integrated units have limitations in battery soft-start. For example, some achieve battery soft-start through a relay series resistor, but cannot achieve black start when the entire system is off-grid; others achieve black start through an external manual switch series resistor, and close the DC main contactor based on the voltage difference before and after the control system is powered on and initialized. However, the auxiliary power source continuously consumes energy during control system initialization, which requires the external manual switch to be continuously pressed during the initialization time, resulting in a poor user experience. Furthermore, this solution is prone to damage to components due to inrush current in the capacitor when closing the DC main contactor after AC soft start (i.e., power-on). Summary of the Invention

[0003] The present invention aims to at least partially solve one of the technical problems in the related art.

[0004] Therefore, the purpose of this invention is to propose a black start and power-on / off circuit for an integrated photovoltaic energy storage and charging machine, so as to solve the problem that the inrush current during power-on can easily damage the components.

[0005] To achieve the above objectives, this invention proposes a black start and power-on / off circuit for an integrated photovoltaic-energy storage-charging system, comprising a photovoltaic device, an energy storage device, a grid connection device, a control device, and a bus capacitor. The bus capacitor is simultaneously connected to the output terminal of the photovoltaic device, the output terminal of the energy storage device, and the machine side of the grid connection device, which is connected to the AC power grid. The energy storage device includes a DC-DC converter module, a battery switch module, and a battery module. The DC-DC converter module includes an input capacitor, a first switch transistor, a first diode connected in parallel with the first switch transistor, a second switch transistor, and a second diode connected in parallel with the second switch transistor. The first terminal of the input capacitor is connected to the positive terminal of the battery module via the battery switch module, and the second terminal of the input capacitor is connected to the negative terminal of the battery module. The common connection point of the first and second switch transistors is connected to the first terminal of the input capacitor. The anode of the first diode and the cathode of the second diode constitute the output terminal of the energy storage device. The battery switch module includes a first branch and a second branch connected in parallel. The first branch includes a first soft-start resistor and a black start switch connected in series, and the second branch includes a start switch. The control device includes a main controller.

[0006] When the photovoltaic device is working and the AC grid is de-energized, the main controller controls the photovoltaic device to charge the bus capacitor. After the bus capacitor is fully charged, the main controller controls the second switch to turn on to charge the input capacitor. After the input capacitor is fully charged, the main controller controls the start switch to close.

[0007] In the black start and power-on / off circuit of the photovoltaic-storage-charging integrated machine provided by the present invention, the grid access device includes an inverter and three switch groups. The three phases of the AC grid are respectively connected to the inverter through the corresponding switch groups. Each switch group includes a second soft-start resistor, a first switch, a second switch and a third switch. The first switch is connected in series with the second switch, and the third switch is connected in series with the second soft-start resistor and then in parallel with the second switch.

[0008] In the black start and power-on / off circuit of the integrated photovoltaic storage and charging machine provided by the present invention, when the AC power grid is energized, the main controller is also used to control the first and third switches in each switch group to close to charge the bus capacitor through the second soft-start resistor. After the bus capacitor is fully charged, the controller controls the second switch in each switch group to close and controls the third switch to open to complete the AC soft start. After the AC soft start is completed, the controller controls the second switch tube to turn on to charge the input capacitor. After the input capacitor is fully charged, the controller controls the start switch to close.

[0009] In the black start and power-on / off circuit of the photovoltaic-storage-charging integrated machine provided by the present invention, the control device further includes a start switch control circuit. When the photovoltaic device is not working and the AC grid is without power, the start switch control circuit is used to monitor the voltage difference between the two ends of the first branch when the black start switch is closed, so as to control the closing of the start switch when the voltage difference meets the requirements.

[0010] In the black start and power-on / off circuit of the integrated photovoltaic storage and charging machine provided by the present invention, the start switch control circuit includes an operational amplifier, a comparator, a first voltage divider resistor, a second voltage divider resistor, and a first protection resistor. The two input terminals of the operational amplifier are respectively connected to the two ends of the first branch, the output terminal of the operational amplifier is connected to the negative input terminal of the comparator, the common connection point of the first voltage divider resistor and the second voltage divider resistor is connected to the positive input terminal of the comparator, and the output terminal of the comparator is connected to the control terminal of the start switch via the first protection resistor.

[0011] In the black start and power-on / off circuit of the integrated photovoltaic storage and charging machine provided by the present invention, the start switch control circuit further includes a third switch tube, the control terminal of the third switch tube is connected to the main controller, and the output terminal of the third switch tube is connected to the output terminal of the comparator.

[0012] In the black start and power-on / off circuit of the integrated photovoltaic storage and charging machine provided by the present invention, when a fault occurs or power-off is required, the main controller sends a high level to the control terminal of the third switch tube to control the start switch to open.

[0013] In the black start and power-on / off circuit of the integrated photovoltaic storage and charging machine provided by the present invention, the start switch is a contactor.

[0014] In the black start and power-on / off circuit of the integrated photovoltaic storage and charging machine provided by the present invention, the first switch, the second switch and the third switch are relays.

[0015] In the black start and power-on / off circuit of the integrated photovoltaic storage and charging machine provided by the present invention, the first switch and the second switch are MOSFETs, and the third switch is a transistor.

[0016] The black start and power-on / off circuit for an integrated photovoltaic-energy storage-charging system provided by this invention includes a photovoltaic device, an energy storage device, a grid connection device, a control device, and a bus capacitor. The bus capacitor is simultaneously connected to the output terminal of the photovoltaic device, the output terminal of the energy storage device, and the machine side of the grid connection device. The grid connection device is connected to the AC power grid on its grid side. The energy storage device includes a DC-DC converter module, a battery switch module, and a battery module. The DC-DC converter module includes an input capacitor, a first switch transistor, a first diode connected in parallel with the first switch transistor, a second switch transistor, and a second diode connected in parallel with the second switch transistor. The first terminal of the input capacitor is connected to the positive terminal of the battery module via the battery switch module. The second terminal of the capacitor is connected to the negative terminal of the battery module. The common connection point of the first and second switching transistors is connected to the first terminal of the input capacitor. The anode of the first diode and the cathode of the second diode constitute the output terminal of the energy storage device. The battery switching module includes a first branch and a second branch connected in parallel. The first branch includes a first soft-start resistor and a black-start switch connected in series, and the second branch includes a start switch. The control device includes a main controller. When the photovoltaic device is working and the AC grid is de-energized, the main controller controls the photovoltaic device to charge the bus capacitor. After the bus capacitor is fully charged, it controls the second switching transistor to conduct to charge the input capacitor. After the input capacitor is fully charged, it controls the start switch to close. In this case, the photovoltaic device charges the bus capacitor until it is fully charged to complete the soft start. Then, it controls the second switching transistor in the DC-DC converter module to conduct to charge the input capacitor. After the input capacitor is fully charged, it controls the start switch to close. This avoids the problem of inrush current caused by directly closing the switch connected to the battery module after the soft start is completed, as is the case in the prior art. This solves the problem of inrush current easily damaging the device during startup.

[0017] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0018] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, wherein:

[0019] Figure 1 A block diagram of a black start and power-on / off circuit for an integrated optical storage and charging device provided in an embodiment of the present invention;

[0020] Figure 2 This is a partial circuit diagram of the black start and power on / off circuit of the integrated optical storage and charging unit provided in an embodiment of the present invention;

[0021] Figure 3 This is a circuit diagram of the start switch control circuit provided in an embodiment of the present invention. Detailed Implementation

[0022] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numerals in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with those of the present invention. Rather, they are merely examples of apparatuses and methods consistent with some aspects of the embodiments of the present invention as detailed in the appended claims.

[0023] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0024] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified. It should also be understood that the term "and / or" as used in this invention refers to and includes any or all possible combinations of one or more associated listed items.

[0025] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0026] This invention proposes a black start and power-on / off circuit for an integrated photovoltaic energy storage and charging machine to solve the problems of inrush current easily damaging components during power-on and excessively long black start time.

[0027] In an embodiment of the present invention, Figure 1 This is a block diagram of a black start and power-on / off circuit for an integrated photovoltaic storage and charging device provided in an embodiment of the present invention. Figure 2 This is a partial circuit diagram of the black start and power on / off circuit of the integrated photovoltaic storage and charging machine provided in an embodiment of the present invention. Figure 1 As shown, the black start and power-on / off circuit of this integrated photovoltaic-energy storage-charging unit includes a photovoltaic device, an energy storage device, a grid connection device, a control device, and a bus capacitor. The bus capacitor is connected to the output terminals of the photovoltaic device, the energy storage device, and the grid connection device (machine side). The grid connection device is connected to the AC power grid on its grid side. The control device is connected to the photovoltaic device, the energy storage device, and the grid connection device.

[0028] In this embodiment, the energy storage device includes a DC-DC converter module, a battery switch module, and a battery module. The positive input terminal of the DC-DC converter module is connected to the positive terminal of the battery module via the battery switch module, and the negative input terminal of the DC-DC converter module is connected to the negative terminal of the battery module. The output terminal of the DC-DC converter module is the output terminal of the energy storage device.

[0029] In this embodiment, the DC-DC conversion module includes an input capacitor, a first switching transistor, a first diode connected in parallel with the first switching transistor, a second switching transistor, and a second diode connected in parallel with the second switching transistor. The first terminal of the input capacitor is connected to the positive terminal of the battery module BAT via a battery switching module, and the second terminal of the input capacitor is connected to the negative terminal of the battery module BAT. The common connection point of the first and second switching transistors is connected to the first terminal of the input capacitor. The DC-DC conversion module may also include an input inductor, with the first terminal of the input inductor connected to the first terminal of the input capacitor, and the second terminal of the input inductor connected to the common connection point of the first and second switching transistors. The first terminal of the input capacitor is the positive input terminal of the DC-DC conversion module, and the second terminal of the input capacitor is the negative input terminal of the DC-DC conversion module. The anode of the first diode and the cathode of the second diode are the output terminals of the DC-DC conversion module; that is, the anode of the first diode and the cathode of the second diode constitute the output terminal of the energy storage device.

[0030] The types of the first and second switching transistors include, but are not limited to, bipolar junction transistors (BJTs), gate turn-off thyristors (GTOs), insulated gate bipolar transistors (IGBTs), integrated gate commutated thyristors (IGCTs), and metal-oxide-semiconductor field-effect transistors (MOSFETs, MOS).

[0031] Taking the example where both the first and second switching transistors are MOSFETs, such as Figure 2 As shown, the DC-DC conversion module includes an input capacitor C1, an input inductor L1, a first MOSFET Q1, a first diode D1, a second MOSFET Q2, and a second diode D2. The first diode D1 and the first MOSFET Q1 are connected in anti-parallel configuration, and the second diode D2 and the second MOSFET Q2 are also connected in anti-parallel configuration. The anode of the first diode D1 and the cathode of the second diode D2 are connected to the two ends of the bus capacitor C2.

[0032] In this embodiment, the battery switch module includes a first branch and a second branch connected in parallel. The first branch includes a first soft-start resistor and a black-start switch connected in series, and the second branch includes a start switch. The black-start switch can be a manual switch, and the start switch can be a contactor.

[0033] Taking a manual black-start switch and a contactor as an example, such as... Figure 2 As shown, the battery switch module includes a first soft-start resistor R1, a manual switch S1, and a contactor S2. The first soft-start resistor R1 is connected in series with the manual switch S1 and then in parallel with the contactor S2.

[0034] In this embodiment, the on / off state of the start switch is controlled by a control device.

[0035] In this embodiment, the photovoltaic device is used to generate electricity using solar energy. The photovoltaic device includes photovoltaic modules (PV) and a transformer module. The transformer module is used to adjust the output voltage of the photovoltaic modules. Figure 2As shown, the transformer module includes capacitor C3, inductor L2, MOSFET Q3, diode D3, and diode D4. MOSFET Q3 and diode D3 are connected in parallel in an anti-parallel configuration. The first terminal of capacitor C3 is connected to the positive output terminal of the photovoltaic module PV and the first terminal of inductor L2. The second terminal of capacitor C3 is connected to the negative output terminal of the photovoltaic module PV and the anode of diode D3. The anode of diode D3 and the cathode of diode D4 constitute the output terminal of the photovoltaic device. The anode of diode D3 and the cathode of diode D4 are connected to the two ends of bus capacitor C2.

[0036] In this embodiment, the grid connection device includes an inverter and three switch groups. The three phases of the AC grid are connected to the inverter via corresponding switch groups. Each switch group includes a second soft-start resistor, a first switch, a second switch, and a third switch. The first switch and the second switch are connected in series, and the third switch is connected in parallel with the second switch after being connected in series with the second soft-start resistor. The first switch, the second switch, and the third switch can be relays.

[0037] Taking the example where the first, second, and third switches all use relays, such as Figure 2 As shown, the grid connection device includes an inverter INV and three switch groups: phase A, phase B, and phase C. The phase A switch group includes phase A first relay SA1, phase A second relay SA2, phase A third relay SA3, and phase A second soft-start resistor R2. The phase B switch group includes phase B first relay SB1, phase B second relay SB2, phase B third relay SB3, and phase B second soft-start resistor R3. The phase C switch group includes phase C first relay SC1, phase C second relay SC2, phase C third relay SC3, and phase C second soft-start resistor R4. The first terminals of phase A first relay SA1, phase B first relay SB1, and phase C first relay SC1 constitute the grid side of the grid connection device, which are connected to the three phases (A, B, and C) of the AC grid, respectively. The second terminals of the first relay SA1 of phase A, the second terminals of the first relay SB1 of phase B, and the second terminals of the first relay SC1 of phase C are respectively connected to the first terminal of the inverter INV via the second relay SA2 of phase A, the second relay SB2 of phase B, and the second relay SC2 of phase C. The second terminal of the inverter INV is connected to the machine side of the grid access device, and the two ends of the bus capacitor C2 at the second terminal of the inverter INV are connected.

[0038] In this embodiment, the black start and power-on / off circuit of the integrated photovoltaic-storage-charging unit may further include an auxiliary power supply device. This auxiliary power supply device powers other electronic components in the black start and power-on / off circuit. Other components include, but are not limited to, an inverter INV and contactors. The auxiliary power supply device includes a DC auxiliary power supply and an AC auxiliary power supply. The DC auxiliary power supply converts DC power into the DC voltage required by the electronic components, and the AC auxiliary power supply converts AC power into the DC voltage required by the electronic components.

[0039] like Figure 2 As shown, the auxiliary power supply device includes a DC auxiliary power supply and an AC auxiliary power supply. The DC auxiliary power supply input terminal is connected to the bus on the inverter INV side, the AC auxiliary power supply input terminal is connected to the AC power grid, and the output terminal (i.e., the DC or AC auxiliary power supply output terminal) is connected to the inverter INV. The auxiliary power supply device supplies power to the inverter INV during operation. It should be noted that... Figure 2 Only the connection between the auxiliary power supply and the inverter INV is shown; the connection between the auxiliary power supply and other components is not shown.

[0040] In this embodiment, the control device includes a main controller. The main controller may be an MCU (Microcontroller Unit).

[0041] In this embodiment, the control device further includes a start switch control circuit. The start switch control circuit includes an operational amplifier, a comparator, a first voltage divider resistor, a second voltage divider resistor, and a first protection resistor. The two input terminals of the operational amplifier are respectively connected to the two ends of the first branch, and the output terminal of the operational amplifier is connected to the negative input terminal of the comparator. The common connection point of the first and second voltage divider resistors is connected to the positive input terminal of the comparator, and the output terminal of the comparator is connected to the control terminal of the start switch via the first protection resistor. The start switch control circuit also includes a third switching transistor. The control terminal of the third switching transistor is connected to the main controller, and the output terminal of the third switching transistor is connected to the output terminal of the comparator.

[0042] Taking a transistor as an example, Figure 3 This is a circuit diagram of the start switch control circuit provided in an embodiment of the present invention. Figure 3 As shown, the start switch control circuit includes operational amplifier U1, comparator U2, first voltage divider resistor R5, second voltage divider resistor R6, and first protection resistor R8. The two input terminals of operational amplifier U1 are connected to the two ends of the first branch (UA and UB are the voltages at the two ends of the first branch). The output terminal of operational amplifier U1 is connected to the negative input terminal of comparator U2. The common connection point of the first voltage divider resistor R5 and the second voltage divider resistor R6 is connected to the positive input terminal of comparator U2. The output terminal of comparator U2 is connected to the control terminal of the start switch via the first protection resistor R8. Figure 3As shown, the start switch control circuit also includes transistor Q4, base resistor R9, pull-down resistor R10, and collector resistor R7. The emitter of transistor Q4 is grounded (GND), and the base of transistor Q4 is connected to the main controller via base resistor R9 to receive the enable signal S2_EN_DSP output by the main controller. The collector of transistor Q4 is connected to the output of comparator U2. The output of comparator U2 outputs the control signal S2_EN.

[0043] In this embodiment, when the photovoltaic device is working and the AC power grid is depleted, the main controller controls the photovoltaic device to charge the bus capacitor. After the bus capacitor is fully charged, the main controller controls the second switch to turn on to charge the input capacitor. After the input capacitor is fully charged, the main controller controls the start switch to close.

[0044] In this embodiment, when the AC power grid is energized, the main controller is also used to control the first and third switches in each switch group to close to charge the bus capacitor through the second soft-start resistor. After the bus capacitor is fully charged, the controller controls the second switch in each switch group to close and controls the third switch to open to complete the AC soft start. After the AC soft start is completed, the controller controls the second switch tube to turn on to charge the input capacitor. After the input capacitor is fully charged, the controller controls the start switch to close.

[0045] In this embodiment, when the photovoltaic device is not working and the AC grid is de-energized, the start switch control circuit monitors the voltage difference across the first branch when the black-start switch is closed, and controls the start switch to close when the voltage difference meets the requirements. When a fault occurs or power-off is required, the main controller sends a high-level signal to the control terminal of the third switch transistor to control the start switch to open.

[0046] Specifically, taking the main controller using an MCU as an example, combined with Figure 2 and Figure 3 The specific operation process of the black start and power on / off circuit of the integrated photovoltaic energy storage and charging unit is as follows:

[0047] 1) When the AC mains is energized, the AC auxiliary power supply operates. The main control MCU closes the first relay SA1 of phase A, the first relay SB1 of phase B, the first relay SC1 of phase C, the third relay SA3 of phase A, the third relay SB3 of phase B, and the third relay SC3 of phase C. This charges the bus capacitor C2 through the second soft-start resistors R2 of phase A, R3 of phase B, and R4 of phase C. After charging is complete, the main control MCU closes the second relays SA2 of phase A, SB2 of phase B, and SC2 of phase C, while simultaneously opening the third relays SA3 of phase A, SB3 of phase B, and SC3 of phase C. The AC soft start is then complete. To avoid inrush current to the input capacitor C1 when the main control MCU closes contactor S2, the main control MCU controls the second MOSFET Q2 to conduct a pulse after the AC soft start is complete, charging the input capacitor C1. Once the input capacitor C1 is fully charged, contactor S2 closes, and the entire system is powered on.

[0048] 2) When the AC mains is de-energized and the PV is energized, the DC auxiliary power source works. The main control MCU controls the PV to boost the voltage and charge the bus capacitor C2. The DC soft start is completed when the bus capacitor C2 is fully charged. To avoid the main control MCU causing an inrush current to the input capacitor C1 when closing contactor S2, the main control MCU controls the second MOS transistor Q2 to conduct a pulse after the DC soft start is completed to charge the input capacitor C1. After the input capacitor C1 is fully charged, the main control MCU closes contactor S2, and the entire system is powered on.

[0049] 3) When the AC mains and PV are both without power, neither the AC auxiliary power supply nor the DC auxiliary power supply works. When the manual switch S1 is closed, the battery module BAT charges the input capacitor C1 and the bus capacitor C2 through the first soft-start resistor R1. During the capacitor charging process, the DC auxiliary power supply starts working. Operational amplifier U1 calculates the voltage difference between points A and B in the first branch. When the voltage difference is less than the set value of 30V, the control signal S2_EN output by comparator U2 is high. At this time, this control signal acts as the contactor S2 energizing signal, causing contactor S2 to close. After contactor S2 closes, the manual switch S1 can be released, the battery soft start is completed, and the entire system starts working, completing the black start. When the system malfunctions or needs to be powered off, the main control MCU sends a high-level enable signal S2_EN_MCU, transistor Q4 conducts, the control signal S2_EN is pulled low, and contactor S2 opens, thus completing the hardware energizing and software disconnecting function for contactor S2. In this scenario, the battery soft start is completed, and the contactor S2 is engaged via hardware circuitry. The manual switch S1 can be released to complete the black start without waiting for the main control MCU to initialize. This avoids the problem of excessively long black start waiting time for users, which is caused by the main control MCU controlling the contactor S2 to engage, requiring the manual switch S1 to remain closed during the contactor S2 engagement process until the soft start and initialization are completed.

[0050] The black start and power-on / off circuit of the photovoltaic-storage-charging integrated machine in this embodiment of the invention includes a photovoltaic device, an energy storage device, a grid connection device, a control device, and a bus capacitor. The bus capacitor is simultaneously connected to the output terminal of the photovoltaic device, the output terminal of the energy storage device, and the machine side of the grid connection device. The grid side of the grid connection device is connected to the AC power grid. The energy storage device includes a DC-DC conversion module, a battery switch module, and a battery module. The DC-DC conversion module includes an input capacitor, a first switch transistor, a first diode connected in parallel with the first switch transistor, a second switch transistor, and a second diode connected in parallel with the second switch transistor. The first terminal of the input capacitor is connected to the positive terminal of the battery module via the battery switch module. The second terminal of the input capacitor is connected to the negative terminal of the battery module. The common connection point of the first and second switching transistors is connected to the first terminal of the input capacitor. The anode of the first diode and the cathode of the second diode constitute the output terminal of the energy storage device. The battery switching module includes a first branch and a second branch connected in parallel. The first branch includes a first soft-start resistor and a black-start switch connected in series, and the second branch includes a start switch. The control device includes a main controller. When the photovoltaic device is working and the AC grid is de-energized, the main controller controls the photovoltaic device to charge the bus capacitor. After the bus capacitor is fully charged, it controls the second switching transistor to conduct to charge the input capacitor. After the input capacitor is fully charged, it controls the start switch to close. In this case, the photovoltaic device charges the bus capacitor until it is fully charged to complete the soft start. Then, it controls the second switching transistor in the DC-DC converter module to conduct to charge the input capacitor. After the input capacitor is fully charged, it controls the start switch to close. This avoids the problem of inrush current caused by directly closing the switch connected to the battery module after the soft start is completed, as is the case in the prior art. This solves the problem of inrush current easily damaging the device during startup.

[0051] The advantages of this invention include: 1) When the AC power grid is energized, the bus capacitor is charged to achieve soft start. After soft start, the Q2 pulse is controlled to charge the input capacitor C1, avoiding the inrush current when the contactor S2 is engaged; 2) When the AC power grid is de-energized but the PV is energized, the PV charges the bus capacitor C2 to achieve soft start. After charging, the Q2 pulse is controlled to charge the input capacitor C1, avoiding the inrush current when the contactor S2 is engaged; 3) When the AC power grid is de-energized and the PV is de-energized, the manual switch S1 is closed to charge the input capacitor C1 and the bus capacitor C2 to achieve soft start. The contactor S2 is engaged by the hardware circuit, which does not rely on the main control MCU, avoiding the main control MCU initialization waiting time and solving the problem of excessively long black start waiting time for users; 4) The contactor S2 realizes the hardware engagement and software disengagement functions.

[0052] The accompanying drawings show structural schematic diagrams according to embodiments disclosed in this invention. These drawings are not drawn to scale, and some details have been enlarged for clarity, and some details may have been omitted. The shapes of the various regions and layers shown in the drawings, as well as their relative sizes and positional relationships, are merely exemplary and may deviate from reality due to manufacturing tolerances or technical limitations. Furthermore, those skilled in the art can design regions / layers with different shapes, sizes, and relative positions as needed.

[0053] It should be understood that the various forms of processes shown above can be used to reorder, add, or delete steps. For example, the steps described in this invention can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution disclosed in this invention can be achieved, and this invention does not impose any limitations on them.

[0054] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A black start and power-on / off circuit for an integrated photovoltaic, energy storage, and charging device, characterized in that, The system includes a photovoltaic device, an energy storage device, a grid connection device, a control device, and a bus capacitor. The bus capacitor is connected to the output terminals of the photovoltaic device, the energy storage device, and the grid connection device. The grid connection device is connected to the AC power grid. The energy storage device includes a DC-DC converter module, a battery switch module, and a battery module. The DC-DC converter module includes an input capacitor, a first switch transistor, a first diode connected in parallel with the first switch transistor, a second switch transistor, and a second diode connected in parallel with the second switch transistor. The first terminal of the input capacitor is connected to the positive terminal of the battery module via the battery switch module, and the second terminal of the input capacitor is connected to the negative terminal of the battery module. The common connection point of the first and second switch transistors is connected to the first terminal of the input capacitor. The anode of the first diode and the cathode of the second diode constitute the output terminal of the energy storage device. The battery switch module includes a first branch and a second branch connected in parallel. The first branch includes a first soft-start resistor and a black-start switch connected in series, and the second branch includes a start switch. The control device includes a main controller. When the photovoltaic device is working and the AC grid is de-energized, the main controller controls the photovoltaic device to charge the bus capacitor. After the bus capacitor is fully charged, the main controller controls the second switch to turn on to charge the input capacitor. After the input capacitor is fully charged, the main controller controls the start switch to close.

2. The black start and power-on / off circuit of the integrated photovoltaic storage and charging machine according to claim 1, characterized in that, The grid connection device includes an inverter and three switch groups. The three phases of the AC grid are respectively connected to the inverter through the corresponding switch groups. Each switch group includes a second soft-start resistor, a first switch, a second switch and a third switch. The first switch is connected in series with the second switch, and the third switch is connected in series with the second soft-start resistor and then in parallel with the second switch.

3. The black start and power-on / off circuit of the integrated photovoltaic storage and charging machine according to claim 2, characterized in that, When the AC power grid is energized, the main controller is also used to control the first and third switches in each switch group to close to charge the bus capacitor through the second soft-start resistor. After the bus capacitor is fully charged, the controller controls the second switch in each switch group to close and controls the third switch to open to complete the AC soft start. After the AC soft start is completed, the controller controls the second switch tube to turn on to charge the input capacitor. After the input capacitor is fully charged, the controller controls the start switch to close.

4. The black start and power-on / off circuit of the integrated photovoltaic storage and charging machine according to claim 1, characterized in that, The control device also includes a start switch control circuit. When the photovoltaic device is not working and the AC grid is without power, the start switch control circuit is used to monitor the voltage difference between the two ends of the first branch when the black start switch is closed, so as to control the closing start switch to close when the voltage difference meets the requirements.

5. The black start and power-on / off circuit of the integrated photovoltaic storage and charging machine according to claim 4, characterized in that, The start switch control circuit includes an operational amplifier, a comparator, a first voltage divider resistor, a second voltage divider resistor, and a first protection resistor. The two input terminals of the operational amplifier are respectively connected to the two ends of the first branch. The output terminal of the operational amplifier is connected to the negative input terminal of the comparator. The common connection point of the first voltage divider resistor and the second voltage divider resistor is connected to the positive input terminal of the comparator. The output terminal of the comparator is connected to the control terminal of the start switch via the first protection resistor.

6. The black start and power-on / off circuit of the integrated photovoltaic storage and charging machine according to claim 5, characterized in that, The start switch control circuit also includes a third switch transistor, the control terminal of which is connected to the main controller, and the output terminal of which is connected to the output terminal of the comparator.

7. The black start and power-on / off circuit of the integrated photovoltaic storage and charging machine according to claim 6, characterized in that, When a fault occurs or power-off is required, the main controller sends a high level to the control terminal of the third switch transistor to control the start switch to open.

8. The black start and power-on / off circuit of the integrated photovoltaic storage and charging machine according to claim 1, characterized in that, The start switch is a contactor.

9. The black start and power-on / off circuit of the integrated photovoltaic storage and charging machine according to claim 2, characterized in that, The first switch, the second switch, and the third switch are all relays.

10. The black start and power-on / off circuit of the integrated photovoltaic storage and charging machine according to claim 6, characterized in that, The first and second switching transistors are MOSFETs, and the third switching transistor is a bipolar transistor.

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