REPLACEMENT OF LEAD BATTERIES WITH LITHIUM BATTERIES

Description

[0001] The invention relates to the field of power supply devices which are connected to photovoltaic panels and which are arranged to supply customer systems (such as telecommunications towers). BACKGROUND OF THE INVENTION

[0002] In rural areas, telecommunications towers play a very important role in connecting millions of people to civil infrastructure and accessing digital services, including health and education.

[0003] Typically, these telecommunications towers are powered by one or more diesel generators (DGs). However, DGs pose a number of environmental disadvantages. They produce carbon dioxide, nitrogen oxide, particulate matter, and other hazardous exhaust gases that are released into the atmosphere.

[0004] Consuming 1 liter of diesel emits an average of 2.7 kg of CO2. Compared to other energy sources, DGs are therefore a very significant source of pollution. In addition, maintenance and fuel costs can significantly increase the operating costs of DGs.

[0005] A power supply solution was therefore designed to power telecommunications towers based on the use of solar energy as the primary energy source and a battery bank as a secondary energy source. Such a power supply solution, particularly suitable for countries with high levels of sunshine, can significantly improve the environmental impact of the energy system and reduce system operating costs.

[0006] Batteries used as a secondary energy source are typically lead-acid batteries. These batteries are used at night and during periods of bad weather.

[0007] However, these lead batteries have a number of disadvantages, including: the depth of discharge: the DOD (for Depth Of Discharge ) of lead-acid batteries should not exceed 50%. Beyond this point, the battery life may be affected; cycle life: lead-acid batteries have a low cycle life that varies between 100 and 300 charge / discharge cycles; efficiency: lead-acid batteries have a reduced efficiency of 80 to 85%; energy density: lead-acid batteries have a low energy density.

[0008] This power supply solution is therefore not entirely satisfactory.

[0009] It was therefore decided to replace lead-acid batteries with lithium batteries, for example lithium-ion batteries, particularly Lithium Iron Phosphate (LiFePO4). These batteries have a high DOD (up to 95%), a good cycle life (typically 1500 charge / discharge cycles), high efficiency (up to 95%) and good energy density. In addition, these batteries require no maintenance or ventilation, unlike lead-acid batteries.

[0010] We therefore obtain a feeding device similar to that of the figure 1 .

[0011] The power supply device 1 is integrated into a cabinet 2 which is connected, on the one hand, to photovoltaic panels 3, and on the other hand, to a telecommunications tower 4. It is therefore this cabinet 2 which supplies the electrical energy to the telecommunications tower 4 for its power supply.

[0012] The power supply device 1 therefore comprises batteries 5, for example of the LiFePO4 type, as well as a solar charge regulator 6, for example of the MPPT type (for Maximum Power Point Tracking ). The power supply device 1 also comprises first protection components 7 intended to protect the regulator 6 against an overvoltage or a current peak coming from the photovoltaic panels 3, second protection components 8 intended to protect the batteries 5, and third protection components 9 intended to protect the telecommunications tower 4 against an overvoltage or a current peak coming from the power supply device 1.

[0013] Lithium 5 batteries are typically equipped with a battery management system 10 (BMS, for Battery Management System).

[0014] The BMS 10 is an electronic system responsible for monitoring, balancing, coordinating and controlling Lithium-ion battery cells. The BMS 10 manages the real-time control of each cell in the battery 5, communicates with external devices, manages the calculation of the SOC (for State Of Charge ) , measures temperature and voltage, etc. For each battery 5, the BMS 10 here comprises a thermal management module 11, a cell management module 12, and a switching module 14 comprising switching MOSFETs.

[0015] It protects the 5 battery from various faults such as overvoltage, overcurrent, undervoltage, overheating, etc.

[0016] In case of an adverse event (undervoltage, overvoltage, etc.), the BMS 10 can isolate and disconnect the cells of the battery 5 using the MOSFETs, which are considered as interfaces between the cells of the battery 5 and the negative and positive external terminals of the battery 5.

[0017] If the switching MOSFETs of battery 5 are disconnected under any event, a voltage must be applied to the output terminals of battery 5 to reactivate it.

[0018] However, two major problems have been detected when replacing lead-acid batteries with lithium batteries (especially LiFePO4).

[0019] The first problem concerns the commissioning of the power supply device 1 following the installation of the new LiFePO4 batteries. During the first installation, a high inrush current is required by the charge regulator 6 to charge its output capacitors C1...CN. This peak current risks damaging the protection circuit of the BMS 10 of each battery 5, which results in damaging the battery 5, which must then be replaced.

[0020] The second problem concerns the current operation of the power supply device 1. If one of the batteries 5 is completely discharged, the BMS 10 disconnects it and isolates it from the rest of the device 1. To reconnect the battery 5, a voltage must be applied to its input. In the absence of such a voltage, the power supply device 1 is not functional and must be started manually to avoid a blackout of energy.

[0021] To solve the first and second problems, a technician must intervene on site equipped with a small diesel generator. This solution is very complicated to implement because, in most cases, telecommunications towers and their power supply system are located in remote areas with very difficult access. The telecommunications service is therefore interrupted for a long period. A prior art patent document discloses a system for starting the controller of a battery powered by a solar panel: EP 2 584 667. SUBJECT OF THE INVENTION

[0022] The object of the invention is, when replacing lead batteries with lithium batteries in a power supply device as previously described, to solve the problems which have just been mentioned without using a diesel generator, and in a simple and inexpensive manner. SUMMARY OF THE INVENTION

[0023] In order to achieve this goal, an electrical circuit is proposed which is arranged to be connected to at least one photovoltaic panel, to at least one main battery and to a charge regulator, and comprising: a first power supply component arranged to, at predefined intervals, generate a first voltage from photovoltaic energy which is produced by the at least one photovoltaic panel; a switching module arranged to, when the first power supply component generates the first voltage, be powered by said first voltage and apply, across the terminals of the at least one main battery and the charge regulator, for a predefined duration, a supply voltage produced from the photovoltaic energy.

[0024] At predefined intervals, the supply voltage is therefore applied automatically and for a predefined duration to the input of the charge regulator and the main batteries.

[0025] This allows the charge controller to charge its output capacitors without requiring a high peak current from the main batteries. When a main battery is completely discharged, the supply voltage allows it to be automatically reconnected.

[0026] The two problems mentioned earlier, which arise when replacing lead-acid batteries with lithium batteries, are therefore resolved.

[0027] The proposed solution does not require on-site intervention by an operator equipped with a diesel generator, since the electrical circuit uses only photovoltaic energy for its power supply.

[0028] The solution is very simple to implement, since it is sufficient to connect the electrical circuit to the photovoltaic panels, the batteries and the charge regulator.

[0029] The electrical circuit produces the supply voltage automatically. It operates autonomously: it does not need to be controlled or powered by another circuit.

[0030] The electrical circuit consists of very few components, and these components are very simple components (no microcontroller, processor, etc.), so the electrical circuit is very inexpensive.

[0031] The invention therefore greatly facilitates the introduction of lithium batteries in applications such as that described above.

[0032] We further propose an electrical circuit as previously described, the first power supply component being powered by an input voltage produced by the at least one photovoltaic panel, the first power supply component being arranged to generate the first voltage when the input voltage is greater than a minimum threshold voltage of the first power supply component.

[0033] We further propose an electrical circuit as previously described, in which the switching module comprises: a second power supply component arranged to be powered by the first voltage and to produce a second voltage; a time relay comprising a switch and arranged to be powered by the second voltage and to, when the second voltage changes from a zero value to a non-zero value, close the switch for the predefined duration to apply the supply voltage to the terminals of the at least one main battery and the charge regulator, then reopen the switch after the predefined duration.

[0034] We further propose an electrical circuit as previously described, the supply voltage being the first voltage.

[0035] We further propose an electrical circuit as previously described, further comprising a secondary battery and a third power supply component, the secondary battery being arranged to be charged by the first power supply component and therefore by photovoltaic energy, the switch of the time relay being mounted between the secondary battery and the third power supply component, the third power supply component being arranged to be supplied by a secondary voltage across the terminals of the secondary battery when the switch is closed, the third power supply component then being arranged to produce a third voltage which is the power supply voltage.

[0036] We further propose equipment comprising a housing and an electrical circuit as previously described, the electrical circuit being positioned in the housing.

[0037] We further propose a power supply device comprising at least one main battery, a charge regulator, and an electrical circuit as previously described.

[0038] A power supply device as previously described is further provided, the at least one main battery being a lithium battery.

[0039] We further propose a method for replacing at least one original battery positioned in a cabinet, in which a charge regulator is also positioned and which is connected to at least one photovoltaic panel, comprising the steps of: removing the at least one original battery from the cabinet; replacing the at least one original battery with at least one main battery; integrating the electrical circuit into the cabinet as previously described, by connecting the electrical circuit to the at least one photovoltaic panel, to the at least one main battery and to the charge regulator.

[0040] Further provided is a replacement method as previously described, wherein the at least one original battery is a lead-acid battery and the at least one main battery is a lithium battery.

[0041] We further propose a power supply method, implemented in the electrical circuit as previously described, and comprising the steps of: de-energize a coil of the time relay; if the input voltage is higher than the minimum threshold voltage of the first supply component, energize the coil and thus close the switch of the time relay; apply the supply voltage to the terminals of the at least one main battery and the charge regulator; have a timing component count the preset time; when the timing component has counted the preset time, open the switch of the time relay.

[0042] The invention will be better understood in light of the following description of particular non-limiting embodiments of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Reference will be made to the attached drawings, including: [ Fig. 1 ] there figure 1 represents a photovoltaic panel, a telecommunications tower and a power supply device of the prior art; [ Fig. 2 ] there figure 2 is a figure similar to the figure 1 , with an electrical circuit according to a first embodiment integrated in the power supply device; [ Fig. 3 ] there figure 3 represents the electrical circuit according to the first embodiment; [ Fig. 4 ] there figure 4 again represents the electrical circuit according to the first embodiment, connected to the photovoltaic panels, the charge regulator and the telecommunications tower; [ Fig. 5 ] there figure 5 represents a control flowchart of the electrical circuit; [ Fig. 6 ] there figure 6 represents the electrical circuit according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0044] In reference to the figure 2 , the invention is here implemented in a power supply device 20.

[0045] The elements of the figure 2 , which are identical to those of the figure 1 , keep their reference.

[0046] The power supply device 20 is connected to at least one photovoltaic panel 3 (in this case several), and to at least one client system, in this case a telecommunications tower 4. The power supply device 20 supplies the at least one client system, i.e. here the telecommunications tower 4.

[0047] The power supply device 20 integrates a charge regulator 6, here of the MPPT type, and at least one main battery 5 (in this case several), which are lithium batteries, here of the LiFePO4 type.

[0048] The power supply device 20 is integrated into a cabinet 2, which here comprises a first input 21, a second input 22, a first output 23 and a second output 24.

[0049] The first input 21 and the second input 22 are connected to two ports of the system formed by the photovoltaic panels 3 (which are connected to each other). The first input 21 is a positive input and the second input 22 is a negative input.

[0050] The first output 23 and the second output 24 are connected to the telecommunications tower 4. The first output 23 is a positive output and the second output 24 is a negative output. The power supply device 20 provides the telecommunications tower 4 with an output current to power it, at an output voltage Vs applied between the first output 23 and the second output 24.

[0051] The charge regulator 6 firstly comprises a first input 25 and a second input 26.

[0052] The first input 21 and the second input 22 of the power supply device 20 are connected respectively, via the first protection components 7, to the first input 25 and the second input 26 of the charge regulator 6. The first input 25 is a positive input and the second input 26 is a negative input.

[0053] The first input 25 and the second input 26 are themselves connected to a first input module 27 of the charge regulator 6, via which the latter therefore acquires the current produced by the photovoltaic panels 3.

[0054] The charge regulator 6 further comprises a third input 29 and a fourth input 30 which are connected, via the second protection components 8, to the terminals of the main batteries 5. The third input 29 is a positive input and the fourth input 30 is a negative input.

[0055] The third input 29 is connected, via the second protection components 8, to the positive terminal 32 of each main battery 5. The main batteries 5 are connected in parallel: the positive terminals 32 of the batteries 5 are connected to each other, and the negative terminals 33 of the batteries 5 are connected to each other. The fourth input 30 is connected, via the second protection components 8, to the negative terminal 33 of each battery 5.

[0056] The third input 29 and the fourth input 30 are themselves connected to a second input module 35 of the charge regulator 6, via which the latter therefore acquires the current produced by the batteries 5.

[0057] The charge regulator 6 further comprises a first output 36 and a second output 37 which are respectively connected, via the third protection components 9, to the first output 23 and to the second output 24 of the cabinet 2. The first output 36 is a positive output and the second output 37 is a negative output.

[0058] The first output 36 and the second output 37 are themselves connected to an output module 38 of the charge regulator 6.

[0059] The charge regulator 6 comprises a first switch S1, a first diode D1, an inductance L, a second switch S2, a second diode D2, the output capacitors C1...CN and a third diode D3.

[0060] The first switch S1, the inductance L, the second diode D2 and the third diode D3 are connected in series.

[0061] The first diode D1, the second switch S2 and the output capacitors C1...CN are connected in parallel with each other.

[0062] The first switch S1 has a terminal connected to the first input 25 via the first input module 27. The anode of the first diode D1 is connected to the second input 26 via the first input module 27.

[0063] The terminals of the output capacitors C1...CN are connected to the third input 29 and the fourth input 30 via the second input module 35. The cathode of the third diode D3 and the negative terminals of the output capacitors are respectively connected to the first output 36 and the second output 37 via the output module 38.

[0064] We are now interested in the implementation of the invention.

[0065] Lithium batteries (here LiFePO4), i.e. the main batteries 5, have been integrated into the power supply system instead of the lead batteries. We are therefore faced with the two problems described earlier: high inrush current required by the charge regulator 6 at start-up, and disconnection by the BMS 10 of a discharged battery 5.

[0066] To overcome these problems, an electrical circuit 40 is integrated into the power supply device 20, and therefore into the cabinet 2.

[0067] We first describe a first embodiment of the electrical circuit. This first embodiment is visible on the figures 3 And 4 .

[0068] The electrical circuit 40 is here integrated into the housing 41 of a small piece of equipment which is positioned and connected in the cabinet 2. This equipment comprises connectors making it possible to connect the electrical circuit 40 to the photovoltaic panels 3 (in any case, to at least one photovoltaic panel 3), to the batteries 5 and to the charge regulator 6.

[0069] The electrical circuit 40 comprises a first input 42 (positive input), a second input 43 (negative input), a first output 44 (positive output) and a second output 45 (negative output).

[0070] When the electrical circuit 40 is integrated into the power supply device 20, the first input 42 is connected to the first input 21 of the cabinet 2, and the second input 43 is connected to the second input 22 of the cabinet 2. The first input 42 and the second input 43 of the electrical circuit 40 are therefore connected to the photovoltaic panels 3.

[0071] We note on the figure 4 that the first protection components 7 include fuses 47.

[0072] The first output 44 of the electrical circuit 40 is connected to the positive terminal 32 of the batteries 5, and therefore, via the second protection components 8 (comprising a circuit breaker 48 for protecting the batteries 5), to the third input 29 of the charge regulator 6. The second output 45 of the electrical circuit 40 is connected to the negative terminal 33 of the batteries 5, and therefore, via the second protection components 8, to the fourth input 30 of the charge regulator 6. It is noted that the second output 45 of the electrical circuit can be connected to an electrical ground of the power supply device 20, which is itself connected to the negative terminals 33 of the batteries 5.

[0073] We note on the figure 4 that the third protection components 9 comprise a circuit breaker 49 for protecting the telecommunications tower 4.

[0074] The electrical circuit 40 comprises a first power supply component 50 and a switching module 51.

[0075] The switching module 51 comprises a second power supply component 52 and a time relay 53 (power relay).

[0076] The electrical circuit 40 also includes an output diode D4.

[0077] The first power supply component 50 and the second power supply component 52 are DC / DC converters (they produce a DC voltage from a DC voltage).

[0078] The first power supply component 50 has a first input 54 (positive input) connected to the first input 42 of the electrical circuit 40, and a second input 55 (negative input) connected to the second input 43 of the electrical circuit 40. The first power supply component 50 has a first output 56 (positive output) and a second output 57 (negative output). The second output 57 is connected to an electrical ground 58 of the electrical circuit 40 (itself connected to an electrical ground of the power supply device 20).

[0079] The second power supply component 52 has a first input 60 (positive input) connected to the first output 56 of the first power supply component 50, and a second input 61 (negative input) connected to the second output 57 of the first power supply component 50 (and thus to the electrical ground 58). The second power supply component 52 has a first output 63 (positive output), and a second output 64 (negative input).

[0080] The time delay relay 53 comprises a coil 65, a timing component 66, and a switch 67.

[0081] The coil 65 comprises a first terminal connected to the first output 63 of the second power supply component 52 and a second terminal connected to the electrical ground 58. The switch 67 comprises a first terminal connected to the first output 56 of the first power supply component 50 and a second terminal connected to the anode of the output diode D4.

[0082] The cathode of the output diode D4 is connected to the third input 29 of the charge regulator 6 via the second protection components 8 and to the positive terminal 32 of each battery 5 (and therefore to the BMS 10 of each battery 5).

[0083] A signal lamp 69 is connected between the second output 57 of the first power supply component 50 and the terminal of the switch 67 which is connected to the anode of the diode D4.

[0084] The operation of the electrical circuit 40 is now described.

[0085] The first power supply component 50 is arranged to, at predefined intervals, generate a first voltage V1 from photovoltaic energy which is produced by the photovoltaic panels 3.

[0086] The switching module 51 is arranged to, when the first power supply component 50 generates the first voltage V1, be powered by said first voltage V1 and apply, to the terminals of the main batteries 5 (terminals 32 and 33) and of the charge regulator 6 (inputs 29 and 30), for a predefined duration, a supply voltage Va produced from the photovoltaic energy.

[0087] The input voltage Ve, produced by the photovoltaic panels 3, supplies the first power supply component 50.

[0088] When the input voltage Ve at the input of the first power supply component 50 is lower than the minimum threshold voltage of the first power supply component 50, the output voltage of the first power supply component is zero.

[0089] When the input voltage Ve is greater (in this case greater than or equal to) the minimum threshold voltage of the first power supply component 50, the first power supply component 50 produces the first voltage V1 from the photovoltaic energy produced by the photovoltaic panels 3.

[0090] The first voltage V1 is a constant and known voltage, which depends on the design of the first power supply component 50 itself.

[0091] When the first power supply component 50 produces the first voltage V1, this supplies the switching module 51, and therefore the second power supply component 52.

[0092] The second power supply component 52 then produces the second voltage V2 (which is also constant and known). The second voltage V2 supplies the time relay 53. The coil 65 of the time relay 53 is activated and, for a predefined period, closes the switch 67.

[0093] This predefined duration, equal to 30 seconds for example, is defined by a setting of the time relay 53, which is carried out for example in the factory.

[0094] Thus, during the predefined duration, the first voltage V1, which is the supply voltage Va, is applied both to the input of the charge regulator 6 and to the terminals of its output capacitors C1...CN, but also to the input of the main batteries 5 and the BMS 10.

[0095] When the supply voltage Va is applied, the signal lamp 69 is lit.

[0096] At the end of the predefined duration, the coil 65 is deactivated, the switch 67 is open, and the supply voltage Va (i.e. the first voltage V1) is no longer applied.

[0097] Thus, when the power supply device 20 is first put into operation with the batteries 5 (lithium), the photovoltaic panels 3 supply the first power supply component 50, and, consequently, the second power supply component 52 is supplied, and the coil 65 of the time relay 53 is activated.

[0098] The time relay 53 uses the available output power of the first power supply component 50 (the current flows via the switch 67) to gradually charge the output capacitors C1...CN of the charge regulator 6. In this way, the peak current, which could damage the BMS circuit 10 of the batteries 5, is eliminated. After counting the time "On Delay" (i.e. the predefined duration, here equal to 30 seconds), the time relay 53 disconnects the electrical circuit 40 (the switch 67 takes the OFF position, i.e. it is open) from the rest of the power supply device 20, which can therefore be started correctly.

[0099] In the case of the second problem, if a main battery 5 is completely discharged (or several batteries 5), the electrical circuit 40, automatically again, will use the available photovoltaic energy to activate the BMS 10 (because it will connect the PV panels 3 to the batteries 5 via the first power component 50).

[0100] Initially, the first power supply component 50 will power the coil 65 of the time delay relay 53 (via the second power supply component 52), and start charging the battery 5 during the "On" time. Delay" of the time relay 53. After this time, the electrical circuit 40 will be disconnected from the rest of the power supply device 20 (the switch 67 takes the OFF position) and the battery 5 begins to be correctly charged by the charge regulator 6. In this way a long period of "Blackout" will be avoided.

[0101] The operation of the electrical circuit 40 is completely automatic. The electrical circuit 40 does not require any “complex” component to control its operation (and no software ) . The electrical circuit 40 operates autonomously. The electrical circuit 40 is powered solely by photovoltaic energy, which enables it to supply the supply voltage Va, automatically, at predefined intervals and for the predefined duration, to the output capacitors C1...CN and to the BMS 10 of each battery 5.

[0102] The supply voltage Va is applied by the electrical circuit 40 automatically, at predefined intervals and for the predefined duration.

[0103] The predefined intervals are therefore daily intervals here. At night, the input voltage Ve produced by the photovoltaic panels 3 is zero, and therefore lower than the minimum threshold voltage of the first power supply component 50, and therefore the output voltage of the first power supply component 50 is zero. The supply voltage Va is zero (and the switch 67 is open).

[0104] Every morning, when the input voltage Ve becomes greater than or equal to the minimum threshold voltage of the first power supply component 50, the latter produces the first voltage V1. The second power supply component 52 is powered and produces the second voltage V2. The coil 65 is then activated. The supply voltage Va, equal to the first voltage V1, is then applied to the input of the batteries 5 and the charge regulator 6 for the predefined duration (here equal to 30 seconds).

[0105] After the predefined duration, the first power supply component 50 continues to produce the first voltage (until the end of the day), but the coil 65 of the time relay 53 is deactivated, the switch 67 is opened, and the electrical circuit 40 is disconnected from the rest of the power supply device 20.

[0106] This operation is carried out every morning of each day, which solves both the problem of the peak current at the first operation of the power supply device 20, but also the reconnection of the main batteries 5 to the rest of the power supply device 20 when they have been completely discharged. It is noted that the predefined intervals are here daily but can be of different duration, because their duration depends on the time at which the input voltage Ve exceeds the predefined threshold (and therefore depends on the sunshine each morning).

[0107] We describe, with reference to the figure 5 , the different stages of the process corresponding to the automatic sequencing of the actions carried out by the electrical circuit 40.

[0108] The following variables are used to describe this sequencing: PV_string_voltage, which is the value of the input voltage Ve; n, which represents the time, i.e. the current instant; D(n), which indicates the state of coil 65 at time n. D = 1 indicates that coil 65 of relay 53 is initialized and can enter a new counting cycle; K1, which indicates the state of switch 67.

[0109] The process begins with a start step E0.

[0110] At time n, if the input voltage (PV_string_voltage) is equal to zero (step E1), the coil 65 of the time relay 53 is de-energized and returns to its initial state: step E2. The value 1 is given to the variable D(n).

[0111] The process returns to step E1.

[0112] In step E1, if the input voltage is not zero, a second condition must be verified to activate the time relay 53: the input voltage Ve must be greater (here greater than or equal to) the minimum threshold voltage (V_start_threshold) of the first power supply component 50: step E3. As long as this is not the case, the process loops back to step E1 (then again to E3).

[0113] In step E3, when the input voltage Ve is greater than or equal to the minimum threshold voltage, the relay 53 can be activated provided that the variable D(n) is equal to 1: step E4.

[0114] If this is not the case, switch 67 remains in the open position (OFF state - blocked): step E5. The process returns to step E1.

[0115] If the variable D(n) is equal to 1, switch 67 is closed (ON state - passing): step E6.

[0116] The photovoltaic panel assembly 3 begins charging the output capacitors C1...CN of the charge controller 6 and the batteries 5 (via the first power supply component 50). The power supply device 20 can then start correctly. The charge controller 6 supplies power to the communication tower 4.

[0117] The timer component 66 starts counting the Time _ delay Td, that is, the predefined duration (equal to 30 seconds for example). The variable n is incremented: step E7.

[0118] The process proceeds to step E8.

[0119] As long as time n is strictly less than the predefined duration, the process loops back to step E6; switch 67 remains closed.

[0120] When the time n becomes greater than or equal to the predefined duration, and therefore when the timing component 66 has counted the predefined duration, the value of the variable D(n) changes to 0: step E9.

[0121] Switch 67 of time relay 53 opens (OFF state - blocked): step E5.

[0122] The process returns to step E1.

[0123] We now describe, with reference to the figure 6 , an electrical circuit 70 according to a second embodiment, which is integrated into a power supply device 71.

[0124] The electrical circuit 70 again comprises a first power supply component 50, a switching module 51 comprising a second power supply component 52 and a time relay 53, and an output diode D4.

[0125] The electrical circuit 70 further comprises a secondary battery 72 and a third power supply component 73 which is a DC / DC converter.

[0126] The first power supply component 50 has a first input 54 (positive input) connected to the first input 42 of the electrical circuit 70, and a second input 55 (negative input) connected to the second input 43 of the electrical circuit 70. The first power supply component 50 has a first output 56 (positive output) and a second output 57 (negative output).

[0127] The second power supply component 52 has a first input 60 (positive input) connected to the first output 56 of the first power supply component 50, and a second input 61 (negative input) connected to the second output 57 of the first power supply component 50. The second power supply component 52 has a first output 63 (positive output), and a second output 64 (negative input).

[0128] The time delay relay 53 comprises a coil 65, a timing component 66, and a switch 67.

[0129] The coil 65 comprises a first terminal connected to the first output 63 of the second power supply component 52 and a second terminal connected to the second output 64 of the second power supply component 52.

[0130] The secondary battery 72 comprises a first input terminal 74 (positive) connected to the first output 56 of the first power component 50 and a second input terminal 75 (negative) connected to the second output 57 of the first power component 50.

[0131] The secondary battery 72 comprises a first output terminal 76 (positive) connected to a first terminal of the switch 67. The second terminal of the switch 67 is connected to a first input 77 (positive) of the third power supply component 73.

[0132] The secondary battery 72 comprises a second output terminal 78 (negative) connected to a second input terminal 79 of the third power component 72.

[0133] The third power supply component 73 comprises a first output 80 (positive) connected to the anode of the output diode D4, and a second output 81 (negative) connected to the electrical ground 58.

[0134] The cathode of the output diode D4 is connected to the first output 44 of the electrical circuit 70, and therefore to the third input 29 of the charge regulator 6 via the second protection components 8 and to the positive terminal 32 of each battery 5 (and therefore to the BMS 10 of each battery 5).

[0135] Again, the electrical circuit 70 is powered by the input voltage Ve produced by the photovoltaic panels 3.

[0136] The first power supply component 50, at predefined intervals, generates the first voltage V1 from the photovoltaic energy which is produced by the photovoltaic panels 3. When the first power supply component 50 generates the first voltage V1, the switching module is powered by the first voltage V1 and applies, to the terminals of the main batteries 5 (terminals 32 and 33) and of the charge regulator 6 (inputs 29 and 30), for the predefined duration, a supply voltage Va produced from the photovoltaic energy.

[0137] The first power supply component 50 generates the first voltage V1 when the input voltage Ve is greater than (or equal to) the minimum threshold voltage of the first power supply component 50. The first voltage supplies the second power supply component 52. The coil 65 is activated and the switch 67 is on for the predefined duration.

[0138] The automatic operation of the electrical circuit 70 is therefore sequenced in the same way as the electrical circuit 40.

[0139] However, this time the supply voltage Va is not the first voltage V1 produced by the first supply component 50.

[0140] The supply voltage Va is a third voltage V3 (constant and known) produced by the third supply component 73 when the latter is supplied by a secondary voltage V' at the terminals of the secondary battery 72.

[0141] The secondary battery 72 is charged by the first power supply component 50, and therefore by the photovoltaic energy, when the first power supply component 50 produces the first voltage V1, that is to say when the input voltage Ve is greater than or equal to the minimum threshold voltage of the first power supply component 50.

[0142] The secondary voltage V' supplies the third power supply component 73 when the switch 67 is closed (ON state).

[0143] This solution is advantageous for the following reason. The secondary battery 72 is continuously recharged by the photovoltaic panels 3 (when the sunshine is sufficient for the input voltage Ve to be greater than or equal to the minimum threshold voltage), and therefore permanently contains a certain quantity of energy.

[0144] This ensures that in the morning, when the switch 67 is closed for the predefined duration, and the day is not very sunny, the quantity of energy that the electrical circuit 70 can provide is sufficient to charge the output capacitors C1...CN of the charge regulator 6 and to activate the BMS 10.

[0145] We now describe how at least one original battery (in this case several) is replaced by at least one main battery 5 (in this case several), in an existing cabinet 2 which is already connected to the photovoltaic panels 3 and to the telecommunications tower 4.

[0146] The original batteries and a charge regulator 6 are positioned in cabinet 2.

[0147] The original batteries are lead-acid batteries.

[0148] The new batteries (5 main batteries) are lithium batteries.

[0149] First, remove the original batteries from cabinet 2.

[0150] Then, the original batteries are replaced with the main batteries 5.

[0151] The equipment comprising the electrical circuit 40, 70, and therefore the electrical circuit 40, 70, is then integrated into the cabinet, by connecting the electrical circuit to the photovoltaic panels 3, to the main batteries 5 and to the charge regulator 6.

[0152] The power supply device can thus start normally and supply power to the telecommunications tower 4.

[0153] This ensures that the power supply device operates without encountering the problems mentioned above.

[0154] Of course, the electrical circuit could also be integrated into the power supply device during its manufacture.

[0155] Of course, the invention is not limited to the embodiments described but encompasses any variant falling within the scope of the invention as defined by the claims.

[0156] It has been indicated here that the power supply device is intended to supply power to a telecommunications tower, but more generally it is intended to supply power to at least one customer system of any kind. This could be one or more electrical installations of any kind, for example a dispensary, one or more dwellings, etc.

[0157] The embodiments described herein are in no way limiting.

[0158] In particular, the switching module could be different from the one described here. For example, one could have a switch and a counter that counts the predefined duration and operates the switch (instead of an "integrated" relay). The second power supply component is not mandatory.

[0159] The supply voltage could be produced differently and for example, in the first embodiment, by a fourth supply component powered by the first supply component.

Claims

1. Electric circuit (40; 70) arranged to be connected to at least one photovoltaic panel (3), to at least one main battery (5) and to a charge regulator (6), and comprising: . a first power supply component (50) arranged to, at predefined intervals, generate a first voltage (V1) from a photovoltaic energy which is produced by the at least one photovoltaic panel (3); . a switching module (51) arranged to, when the first power supply component (50) generates the first voltage (V1), be powered by said first voltage and apply, to the terminals of the at least one main battery and of the charge regulator, for a predefined duration, a power supply voltage (Va) produced from the photovoltaic energy.

2. Electric circuit according to claim 1, the first power supply component (50) being powered by an input voltage (Ve) produced by the at least one photovoltaic panel (3), the first power supply component being arranged to generate the first voltage (V1) when the input voltage (Ve) is greater than a minimum threshold voltage of the first power supply component.

3. Electric circuit according to one of the preceding claims, wherein the switching module comprises: . a second power supply component (52) arranged to be powered by the first voltage (V1) and to produce a second voltage (V2); . a timer relay (53) comprising a switch (67) and arranged to be powered by the second voltage (V2) and to, when the second voltage (V2) moves from a zero value to a non-zero value, close the switch (67) for the predefined duration to apply the power supply voltage (Va) at the terminals of the at least one main battery (5) and of the charge regulator (6), then reopen the switch following the predefined duration.

4. Electric circuit according to claim 3, the power supply voltage (Va) being the first voltage (V1).

5. Electric circuit according to claim 3, further comprising a secondary battery (72) and a third power supply component (73), the secondary battery being arranged to be charged by the first power supply component (50) and therefore by the photovoltaic energy, the switch (67) of the timer relay (53) being mounted between the secondary battery and the third power supply component, the third power supply component (73) being arranged to be powered by a secondary voltage (V') at the terminals of the secondary battery (72) when the switch (67) is closed, the third power supply component thus being arranged to produce a third voltage (V3) which is the power supply voltage (Va).

6. Equipment comprising a casing (41) and an electric circuit (40; 70) according to one of the preceding claims, the electric circuit being positioned in the casing.

7. Power supply device (20; 71) comprising at least one main battery (5), a charge regulator (6), and an electric circuit (40; 70) according to one of claims 1 to 5.

8. Power supply device (20; 71) according to claim 7, the at least one main battery (5) being a lithium battery.

9. Method for replacing at least one original battery positioned in a cabinet (2), wherein a charge regulator (6) is also positioned, and which is connected to at least one photovoltaic panel (3), comprising the steps of: . removing the at least one original battery from the cabinet; . replacing the at least one original battery with at least one main battery (5); . integrating the electric circuit (40; 70) according to one of claims 1 to 5 in the cabinet, by connecting the electric circuit to the at least one photovoltaic panel (3), to the at least one main battery (5) and to the charge regulator (6).

10. Method according to claim 9, wherein the at least one original battery is a lead battery and the at least one main battery is a lithium battery.

11. Power supply method, implemented in the electric circuit (40; 70) according to claims 2 and 3, and comprising the steps of: . de-energising a coil (65) of the timer relay (53); . if the input voltage (Ve) is greater than the minimum threshold voltage of the first power supply component (50), energising the coil and thus closing the switch (67) of the timer relay (53); . applying the power supply voltage (Va) to the terminals of the at least one main battery (5) and of the charge regulator (6); . counting the predefined duration by a time delay component (66); . when the time delay component (66) has counted the predefined duration, opening the switch (67) of the timer relay (53).