Photovoltaic power supply system

Abstract

The invention provides a photovoltaic power supply system, and the system comprises a photovoltaic array which converts optical energy into electric energy; the photovoltaic energy storage inverter is used for converting the electric energy output by the photovoltaic array into direct-current electric energy, grid-connected alternating-current electric energy and off-grid alternating-current electric energy, outputting the grid-connected alternating-current electric energy to the grid-connected interface and outputting the off-grid alternating-current electric energy to the off-grid interface; and the lithium battery module is charged based on the direct-current electric energy to store the direct-current electric energy, or outputs electric energy to the photovoltaic energy storage inverter, converts the electric energy output by the lithium battery module into alternating-current electric energy and outputs the alternating-current electric energy, and is in a dischargeable and charging forbidden state under the condition that the temperature of the lithium battery module is lower than a preset temperature threshold value. The direct-current electric energy can charge the lithium battery module, and the lithium battery module is in a dischargeable and charging forbidden state when the temperature of the lithium battery module is lower than the preset temperature threshold value, so that the problem that the lithium battery is fed and cannot be self-repaired under the conditions of cloudy days, low-temperature operation or abuse of the photovoltaic power supply system is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of photovoltaic power generation, and in particular to a photovoltaic power supply system. Background Art

[0002] Photovoltaic power supply system is a common outdoor power supply equipment, favored by some outdoor enthusiasts. However, ordinary users do not understand the characteristics of photovoltaic and energy storage batteries of photovoltaic power supply system, which leads to common abuse and they do not know how to maintain it. For example, long-term cloudy weather causes lithium battery to not be recharged in time, resulting in lithium battery feeding. Long-term use of high-power electrical appliances at night causes lithium battery feeding. In winter, when the temperature is below zero, the lithium battery can only be discharged but not charged, resulting in lithium battery feeding.

[0003] Therefore, existing photovoltaic power supply systems have the problem of being unable to self-repair due to lithium battery power failure when operating on cloudy days, at low temperatures, or under abuse conditions. Summary of the invention

[0004] In view of this, it is necessary to provide a photovoltaic power supply system to solve the technical problem that the existing photovoltaic power supply system cannot self-repair due to lithium battery power supply caused by cloudy days, low temperature operation or abuse.

[0005] In order to solve the above problems, on the one hand, the present invention provides a photovoltaic power supply system, comprising: Photovoltaic arrays, which convert light energy into electricity; A photovoltaic energy storage inverter, electrically connected to the photovoltaic array, for converting the electric energy output by the photovoltaic array into direct current electric energy, grid-connected alternating current electric energy and off-grid alternating current electric energy, and outputting the grid-connected alternating current electric energy to the grid-connected interface, and outputting the off-grid alternating current electric energy to the off-grid interface; The lithium battery module is electrically connected to the photovoltaic energy storage inverter and is used to charge based on the DC power to store the DC power, or output power to the photovoltaic energy storage inverter to convert the power output by the lithium battery module into AC power output through the photovoltaic energy storage inverter, and when the temperature of the lithium battery module is lower than a preset temperature threshold, it is in a dischargeable and charging prohibited state.

[0006] In a possible implementation, the lithium battery module includes: Pre-charging circuit; Low temperature unidirectional discharge protection circuit; A lithium battery pack is electrically connected to the photovoltaic energy storage inverter through the low-temperature unidirectional discharge protection circuit and the pre-charging circuit; the lithium battery pack includes a plurality of lithium batteries connected in series; Low temperature heating circuit; The BMS management unit is electrically connected to the pre-charging circuit, the low-temperature heating circuit and the low-temperature unidirectional discharge protection circuit, respectively, and is used to control the pre-charging circuit to be turned on to charge the lithium battery pack, and when the temperature of the lithium battery module is lower than a preset temperature threshold, control the low-temperature heating circuit to heat the lithium battery pack, and when the temperature of the lithium battery module is lower than a preset temperature threshold, control the lithium battery pack to enter a dischargeable and charging prohibited state.

[0007] In a possible implementation, the pre-charging circuit includes: a first DC contactor, a second DC contactor, and a first resistor; The second DC contactor is connected in series with the first resistor and then connected in parallel with the first DC contactor; The BMS management unit is further configured to, when the first DC contactor is disconnected, first close the second DC contactor, and then control the first DC contactor to close after a set time, and then control the second DC contactor to disconnect.

[0008] In a possible implementation, the low-temperature unidirectional discharge protection circuit includes: a first unidirectional diode, a first temperature-controlled switch and a first fuse; The first unidirectional diode is connected in parallel with the first temperature-controlled switch and then connected in series with the first fuse; The BMS management unit is further used to control the first temperature control switch to be disconnected when the temperature of the lithium battery is lower than a preset temperature threshold, and to control the first temperature control switch to be closed when the temperature of the lithium battery is higher than the preset temperature threshold.

[0009] In a possible implementation, the low-temperature heating circuit includes a second temperature-controlled switch, a second fuse, and a heating wire connected in series; The BMS management unit is also used to control the second temperature control switch to be normally closed when the temperature of the lithium battery pack is lower than a preset temperature threshold, and to control the second temperature control switch to be normally open when the temperature of the lithium battery pack is higher than the preset temperature threshold.

[0010] In a possible implementation, the lithium battery module further includes: an internal and external dual power supply dual startup circuit; The internal and external dual power supply dual startup circuit includes: a power module (DC / DC), a second unidirectional diode, a third unidirectional diode and a fourth unidirectional diode; The power module is connected to the BMS management unit through the third unidirectional diode, and is used to provide power to the BMS management unit; The BMS management unit is also connected to an external power supply interface through the second unidirectional diode, and the external power supply interface is used to receive electrical energy outside the lithium battery module; The BMS management unit is also connected to the internal power interface through the fourth unidirectional diode, and the internal power interface is used to output the electrical energy inside the lithium battery module.

[0011] In a possible implementation, the BMS management unit has a built-in energy consumption balancing circuit.

[0012] In a possible implementation, the lithium battery pack is provided with an external balancing line connected to the balancing interface.

[0013] In a possible implementation, the photovoltaic power system further includes: The switching power supply is used to convert the AC power of the photovoltaic energy storage inverter into control power, and output the control power to the BMS management unit.

[0014] In a possible implementation, the photovoltaic power system further includes: Display device; The main controller is used to obtain the working status information of the photovoltaic energy storage inverter and the lithium battery module, and forward the status information to the display device for display.

[0015] The beneficial effect of adopting the above-mentioned implementation method is: the photovoltaic power supply system provided by the present invention includes: a photovoltaic array, which is used to convert light energy into electrical energy; a photovoltaic energy storage inverter, which is electrically connected to the photovoltaic array, and is used to convert the electrical energy output by the photovoltaic array into DC electrical energy and AC electrical energy, and output the AC electrical energy to the grid-connected interface; a lithium battery module, which is electrically connected to the photovoltaic energy storage inverter, and is used to charge based on the DC electrical energy to store the DC electrical energy, or output electrical energy to the photovoltaic energy storage inverter, so as to convert the electrical energy output by the lithium battery module into AC electrical energy output through the photovoltaic energy storage inverter, and when the temperature of the lithium battery module is lower than a preset temperature threshold, it is in a dischargeable and charging prohibited state.

[0016] In the photovoltaic power supply system provided by the present invention, after the photovoltaic array converts light energy into electrical energy, it is converted into direct current and alternating current through a photovoltaic energy storage inverter. The alternating current can be used as city electricity for power supply, and the direct current can be used to charge the lithium battery module, which greatly reduces the possibility of power feeding of the lithium battery module on cloudy days or under conditions of abuse, and helps the lithium battery module to self-repair. When the temperature of the lithium battery module is lower than the preset temperature threshold, it is in a state where it can be discharged and charging is prohibited, thereby realizing low-temperature unidirectional amplification protection of the lithium battery module and preventing the lithium battery module from being unable to self-repair due to power feeding. Therefore, the present invention can solve the technical problem that the existing photovoltaic power supply system has the problem of lithium battery power feeding due to cloudy days, low-temperature operation or abuse, and thus being unable to self-repair. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0018] Figure 1 A schematic structural diagram of an embodiment of a photovoltaic power supply system provided by the present invention; Figure 2 This is a schematic structural diagram of an embodiment of a lithium battery module in a photovoltaic power supply system provided by the present invention. DETAILED DESCRIPTION

[0019] 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 only 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 those skilled in the art without creative work are within the scope of protection of the present invention.

[0020] In the description of the embodiments of the present application, unless otherwise specified, “plurality” means two or more than two.

[0021] The terms "including" and "having" and any variations thereof in the embodiments of the present invention are intended to cover non-exclusive inclusions. For example, a process, method, apparatus, product or equipment comprising a series of steps or modules is not necessarily limited to those steps or modules clearly listed, but may include other steps or modules not clearly listed or inherent to these processes, methods, products or equipment.

[0022] The naming or numbering of the steps in the embodiments of the present invention does not mean that the steps in the method flow must be executed in the time / logical sequence indicated by the naming or numbering. The execution order of the named or numbered process steps can be changed according to the technical purpose to be achieved, as long as the same or similar technical effects can be achieved.

[0023] Reference to an "embodiment" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiment may be included in at least one embodiment of the present invention. The appearance of the phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0024] like Figure 1 As shown, the present invention provides a photovoltaic power supply system, comprising: Photovoltaic array 101, used to convert light energy into electrical energy; The photovoltaic energy storage inverter 102 is electrically connected to the photovoltaic array 101, and is used to convert the electric energy output by the photovoltaic array 101 into direct current electric energy, grid-connected alternating current electric energy and off-grid alternating current electric energy, and output the grid-connected alternating current electric energy to the grid-connected interface, and output the off-grid alternating current electric energy to the off-grid interface; The lithium battery module 103 is electrically connected to the photovoltaic energy storage inverter 102, and is used to charge based on the DC power to store the DC power, or output power to the photovoltaic energy storage inverter 102, so as to convert the power output by the lithium battery module 103 into AC power output through the photovoltaic energy storage inverter 102, and when the temperature of the lithium battery module 103 is lower than a preset temperature threshold, it is in a dischargeable and charging prohibited state.

[0025] It is understandable that the photovoltaic power supply system provided by the present invention includes: a photovoltaic array 101 (PV), a photovoltaic energy storage inverter 102 (PV Inverter), a lithium battery module 103 (BAT), a switching power supply 104 (AC / DC), a main controller 105 (MCU), and a touch screen 106 (OP). The temperature of the lithium battery module 103 further refers to the temperature of the lithium battery pack inside the lithium battery model.

[0026] The photovoltaic array 101 is used to convert light energy into electrical energy; The photovoltaic energy storage inverter 102 is used to convert the input power of the photovoltaic array 101 into direct current power, grid-connected alternating current power and off-grid alternating current power, and output the alternating current power to the grid-connected interface and the off-grid alternating current power to the off-grid interface; The lithium battery module 103 is used to store the DC output power of the photovoltaic energy storage inverter 102; The switching power supply 104 is used to convert the AC power of the photovoltaic energy storage inverter 102 into control power; The main controller 105 is used for internal status monitoring and external communication of the photovoltaic power system; The touch screen 106 is used for photovoltaic power system status display, data analysis and data storage.

[0027] The photovoltaic energy storage inverter 102 converts the variable DC power generated by the photovoltaic array 101 into fixed DC power and AC power of the mains frequency, which can realize off-grid and grid-connected power generation functions and realize two-way automatic control conversion of electric energy.

[0028] The photovoltaic energy storage inverter 102 has photovoltaic interfaces PV1, PV2, lithium battery interface BAT, grid-connected interface GI, off-grid interface OGI, communication interface CAN, etc. When any one or more inputs exist in the photovoltaic interface, lithium battery interface, and grid-connected interface, the off-grid interface has AC power output.

[0029] In some embodiments, the lithium battery module 103 includes: Pre-charging circuit; Low temperature unidirectional discharge protection circuit; A lithium battery pack is electrically connected to the photovoltaic energy storage inverter 102 through the low-temperature unidirectional discharge protection circuit and the pre-charging circuit; the lithium battery pack includes a plurality of lithium batteries connected in series; the lithium battery pack is provided with an external equalization line connected to the equalization interface; Low temperature heating circuit; The BMS management unit is electrically connected to the pre-charging circuit, the low-temperature heating circuit and the low-temperature unidirectional discharge protection circuit, respectively, and is used to control the pre-charging circuit to be turned on to charge the lithium battery pack, and when the temperature of the lithium battery module 103 is lower than a preset temperature threshold, control the low-temperature heating circuit to heat the lithium battery pack, and when the temperature of the lithium battery module 103 is lower than a preset temperature threshold, control the lithium battery pack to enter a dischargeable and charging prohibited state.

[0030] It can be understood that the lithium battery module 103 includes a lithium battery pack BT, a low-temperature heating circuit, a pre-charging circuit, a low-temperature unidirectional discharge protection circuit, a current sensor A1, a management unit BMS, a power module DC / DC, an external balancing circuit, an internal and external dual power supply dual starting circuit, as well as a power interface JI, a power-on interface J2, a balancing interface J3, an external power supply interface J4, an internal power supply interface J5, a communication interface J6, etc.

[0031] The lithium battery pack BT is composed of a plurality of lithium batteries in series and in parallel. When the battery pack BT is assembled, a temperature probe of the temperature switch KM3 and a temperature probe of the temperature switch KM4 are pre-buried. The battery pack series nodes are externally connected to a voltage acquisition line and an external balancing line.

[0032] The battery pack BT of the lithium battery module 103 is pre-equipped with an external equalization line, which is connected to the equalization interface J3 and is used for external supplementary charging equipment maintenance after abuse.

[0033] refer to Figure 2 The low-temperature heating circuit is used to realize the low-temperature heating function of the lithium battery pack. It is mainly composed of a temperature switch KM4, a fuse F2, and a heating wire TC1 in series. Both ends are connected to the main circuit line, close to the power interface J1. The temperature switch KM4 temperature probe and the heating wire TC1 are pre-buried in the lithium battery pack to facilitate monitoring the BT temperature of the lithium battery pack and heating the BT of the lithium battery pack.

[0034] Execution method of the low-temperature heating circuit of the lithium battery module 103: When the temperature switch KM4 temperature probe monitors that the temperature of the lithium battery pack BT is lower than the temperature switch setting value Ta (ie, the preset temperature threshold), the temperature switch KM4 changes from normally open to normally closed, and the heating wire TC1 works to heat the lithium battery pack BT; when the temperature probe monitors that the temperature of the lithium battery pack BT is higher than the temperature switch KM4 setting value Ta, the temperature switch KM4 changes from normally closed to normally open, and the heating wire TC1 stops working; this low-temperature heating circuit execution method is autonomous and controllable, and is not restricted by the BMS management unit.

[0035] The low-temperature unidirectional discharge protection circuit is used for discharging but not charging when the temperature of the battery pack is lower than 0°C (or other preset temperature thresholds), and is mainly composed of a DC contactor KM1, a DC contactor KM2, a resistor R1, a current unidirectional diode D1, a temperature control switch KM3, and a fuse F1; the DC contactor KM2 is connected in series with the resistor R1, and then connected in parallel with the DC contactor KM1 to form a pre-charging circuit; the unidirectional diode D1 and the temperature control switch KM3 are connected in parallel to form a low-temperature unidirectional discharge protection circuit; the pre-charging circuit, the low-temperature unidirectional discharge protection circuit, the battery pack, and the current sensor are connected in series to form a main circuit, and both ends are connected to the power interface J1.

[0036] Pre-charging strategy: When DC contactor KM1 is disconnected, first close DC contactor KM2, then close DC contactor KM1 after S1 time, and then disconnect DC contactor KM2.

[0037] Implementation method of low-temperature unidirectional discharge protection circuit: When the temperature control switch KM3 detects that the temperature of the lithium battery pack BT is lower than 0℃, the temperature control switch KM3 changes from closed to open, and the current can only pass through the unidirectional diode D1. The unidirectional diode D1 limits the battery pack BT to discharge but not charge, providing low-temperature discharge protection for the battery pack BT; when the temperature control switch KM3 detects that the temperature of the lithium battery pack BT is higher than 0℃, the temperature control switch KM3 changes from open to closed, and the current passes through the temperature control switch KM3. The current can flow in both directions, and the lithium battery pack can be charged or discharged; this low-temperature unidirectional discharge protection circuit implementation method is autonomous and controllable, and is not restricted by the BMS management unit.

[0038] In some embodiments, Figure 2 As shown, the pre-charging circuit includes: a first DC contactor KM1, a second DC contactor KM2 and a first resistor R1.

[0039] The second DC contactor KM2 is connected in series with the first resistor R1 and then connected in parallel with the first DC contactor KM1.

[0040] The BMS management unit is further used for, when the first DC contactor KM1 is disconnected, first closing the second DC contactor KM2, and then controlling the first DC contactor KM1 to close after a set time, and then controlling the second DC contactor KM2 to disconnect.

[0041] In some embodiments, Figure 2 As shown, the low-temperature unidirectional discharge protection circuit includes: a first unidirectional diode D1, a first temperature-controlled switch KM3 and a first fuse F1; The first unidirectional diode D1 is connected in parallel with the first temperature control switch KM3 and then connected in series with the first fuse F1; The BMS management unit is further used to control the first temperature control switch KM3 to be disconnected when the temperature of the lithium battery is lower than a preset temperature threshold (for example, 0°C), and to control the first temperature control switch KM3 to be closed when the temperature of the lithium battery is higher than the preset temperature threshold.

[0042] In some embodiments, the low temperature heating circuit includes a second temperature control switch KM4, a second fuse F2 and a heating wire TC1 connected in series; The BMS management unit is also used to control the second temperature control switch KM4 to be normally closed when the temperature of the lithium battery pack is lower than a preset temperature threshold, and to control the second temperature control switch KM4 to be normally open when the temperature of the lithium battery pack is higher than the preset temperature threshold.

[0043] In some embodiments, Figure 2 As shown, the lithium battery module 103 further includes: an internal and external dual power supply dual startup circuit; The internal and external dual power supply dual startup circuit includes: a power supply module DC / DC, a second unidirectional diode D2, a third unidirectional diode D3 and a fourth unidirectional diode D4; The power module is connected to the BMS management unit through the third unidirectional diode D3, and is used to provide power to the BMS management unit; The BMS management unit is also connected to the external power interface J4 through the second unidirectional diode D2, and the external power interface J4 is used to receive electrical energy outside the lithium battery module 103; The BMS management unit is also connected to the internal power interface J5 through the fourth unidirectional diode D4, and the internal power interface J5 is used to output the electric energy converted by the DC / DC of the internal power module of the lithium battery module 103.

[0044] The BMS management unit has a built-in energy consumption balancing circuit.

[0045] It can be understood that the internal and external dual power supply dual startup circuit includes a power supply module DC / DC, unidirectional diodes D2, D3, D4, an external power supply interface J4, an internal power supply interface J5, a switching power supply AC / DC, etc. to form a dual power supply.

[0046] Internal and external dual power supply dual startup circuit execution method: When the lithium battery pack BT feed power module DC / DC cannot work, as long as the photovoltaic array 101 provides power input, the photovoltaic energy storage inverter 102 off-grid interface OGI outputs AC power, the switching power supply AC / DC generates control power, and provides control power to the BMS management unit through the external power interface J4 and the unidirectional diode D2, and the photovoltaic power system starts to run. When the photovoltaic array 101 does not provide power input and the lithium battery pack BT power is normal, the power module DC / DC generates control power, and provides control power to the outside through the unidirectional diode D3, the unidirectional diode D4, and the internal power interface J5. At the same time, the photovoltaic energy storage inverter 102 starts, the off-grid interface OGI outputs AC power, the switching power supply AC / DC works, and the photovoltaic power system starts to run. When the lithium battery pack BT has normal power and the photovoltaic array 101 provides power input, the internal switching power supply AC / DC of the lithium battery module 103 and the external switching power supply AC / DC work normally, and the unidirectional diodes D2, D3, and D4 are used to ensure that the power is balanced and does not conflict, and the photovoltaic power supply system starts to operate.

[0047] The hardware of the BMS management unit has a digital input interface, a digital output interface, an analog input interface, an analog output interface, a measuring resistance input interface, a CAN communication interface, a serial communication interface, and a built-in energy consumption balancing circuit; the BMS management unit monitors the temperature, voltage, current, etc. of the lithium battery pack, controls KM1 and KM2, etc., performs energy consumption balancing at the end of charging, and exchanges information with the outside through the communication interface.

[0048] In some embodiments, the photovoltaic power system further includes: The switching power supply 104 is used to convert the AC power of the photovoltaic energy storage inverter 102 into control power, and output the control power to the BMS management unit.

[0049] In some embodiments, the photovoltaic power system further includes: Display device; The main controller 105 is used to obtain the working status information of the photovoltaic energy storage inverter 102 and the lithium battery module 103, and forward the status information to the display device for display.

[0050] The photovoltaic power supply system provided by the present invention is introduced in detail above. Specific examples are used in this article to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as a limitation on the present invention.

Claims

1. A photovoltaic power supply system, characterized in that: include: Photovoltaic arrays, which convert light energy into electricity; A photovoltaic energy storage inverter, electrically connected to the photovoltaic array, for converting the electric energy output by the photovoltaic array into direct current electric energy, grid-connected alternating current electric energy and off-grid alternating current electric energy, and outputting the grid-connected alternating current electric energy to the grid-connected interface, and outputting the off-grid alternating current electric energy to the off-grid interface; The lithium battery module is electrically connected to the photovoltaic energy storage inverter and is used to charge based on the DC power to store the DC power, or output power to the photovoltaic energy storage inverter to convert the power output by the lithium battery module into AC power output through the photovoltaic energy storage inverter, and when the temperature of the lithium battery module is lower than a preset temperature threshold, it is in a dischargeable and charging prohibited state.

2. The photovoltaic power supply system according to claim 1, characterized in that: The lithium battery module comprises: Pre-charging circuit; Low temperature unidirectional discharge protection circuit; A lithium battery pack is electrically connected to the photovoltaic energy storage inverter through the low-temperature unidirectional discharge protection circuit and the pre-charging circuit; the lithium battery pack includes a plurality of lithium batteries connected in series; Low temperature heating circuit; The BMS management unit is electrically connected to the pre-charging circuit, the low-temperature heating circuit and the low-temperature unidirectional discharge protection circuit, respectively, and is used to control the pre-charging circuit to be turned on to charge the lithium battery pack, and when the temperature of the lithium battery module is lower than a preset temperature threshold, control the low-temperature heating circuit to heat the lithium battery pack, and when the temperature of the lithium battery module is lower than a preset temperature threshold, control the lithium battery pack to enter a dischargeable and charging prohibited state.

3. The photovoltaic power supply system according to claim 2, characterized in that: The pre-charging circuit comprises: a first DC contactor, a second DC contactor and a first resistor; The second DC contactor is connected in series with the first resistor and then connected in parallel with the first DC contactor; The BMS management unit is further configured to, when the first DC contactor is disconnected, first close the second DC contactor, and then control the first DC contactor to close after a set time, and then control the second DC contactor to disconnect.

4. The photovoltaic power supply system according to claim 2, characterized in that: The low-temperature unidirectional discharge protection circuit comprises: a first unidirectional diode, a first temperature-controlled switch and a first fuse; The first unidirectional diode is connected in parallel with the first temperature-controlled switch and then connected in series with the first fuse; The BMS management unit is further used to control the first temperature control switch to be disconnected when the temperature of the lithium battery is lower than a preset temperature threshold, and to control the first temperature control switch to be closed when the temperature of the lithium battery is higher than the preset temperature threshold.

5. The photovoltaic power supply system according to claim 2, characterized in that: The low-temperature heating circuit comprises a second temperature-controlled switch, a second fuse and a heating wire connected in series; The BMS management unit is also used to control the second temperature control switch to be normally closed when the temperature of the lithium battery pack is lower than a preset temperature threshold, and to control the second temperature control switch to be normally open when the temperature of the lithium battery pack is higher than the preset temperature threshold.

6. The photovoltaic power supply system according to claim 2, characterized in that: The lithium battery module further includes: an internal and external dual power supply dual start-up circuit; The internal and external dual power supply dual startup circuit includes: a power supply module, a second unidirectional diode, a third unidirectional diode and a fourth unidirectional diode; The power module is connected to the BMS management unit through the third unidirectional diode, and is used to provide power to the BMS management unit; The BMS management unit is also connected to an external power supply interface through the second unidirectional diode, and the external power supply interface is used to receive electrical energy outside the lithium battery module; The BMS management unit is also connected to the internal power interface through the fourth unidirectional diode, and the internal power interface is used to output the electrical energy inside the lithium battery module.

7. The photovoltaic power supply system according to claim 2, characterized in that: The BMS management unit has a built-in energy consumption balancing circuit.

8. The photovoltaic power supply system according to claim 2, characterized in that: The lithium battery pack is provided with an external equalization line connected to the equalization interface.

9. The photovoltaic power supply system according to claim 2, characterized in that: Also includes: The switching power supply is used to convert the AC power of the photovoltaic energy storage inverter into control power, and output the control power to the BMS management unit.

10. The photovoltaic power supply system according to any one of claims 1 to 9, characterized in that: Also includes: Display device; The main controller is used to obtain the working status information of the photovoltaic energy storage inverter and the lithium battery module, and forward the status information to the display device for display.

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