Pre-charging circuit and energy storage power supply

Abstract

The utility model provides a pre-charging circuit and an energy storage power supply. The pre-charging circuit comprises a constant current driving module, a pre-charging switch module, a power supply switch module and a voltage conversion module; the constant current driving module is respectively connected with the pre-charging switch module and the photovoltaic power supply, the pre-charging switch module is also connected with the voltage conversion module, and the power supply switch module is respectively connected with the photovoltaic power supply and the voltage conversion module; the constant-current driving module is used for outputting a constant-current signal when the input voltage of the photovoltaic power supply is greater than or equal to a first preset voltage so as to drive the pre-charging switch module to work, so that the photovoltaic power supply pre-charges a capacitor in the voltage conversion module through the pre-charging switch module; the power supply switch module is used for conducting when the voltage of the capacitor is greater than a preset value, so that the photovoltaic power supply supplies power to the voltage conversion module through the power supply switch module. According to the circuit, the surge current at the initial stage of capacitor charging can be reduced, meanwhile, smooth transition from pre-charging to normal power supply can be achieved, and the safety and stability of the circuit are improved.

Description

TECHNICAL FIELD

[0001] The embodiment of the present application relates to the technical field of electronic circuit, in particular to a pre-charging circuit and an energy storage power supply. BACKGROUND

[0002] At present, the number of house car owners increases, and it is common to use solar panels outdoors to supply power to household appliances. Because the open circuit voltage of solar energy is large, the PV (Photovoltaic) charger is usually equipped with an input pre-charging circuit. At the same time, the house car will pass through the sunlight-free zone, and the frequent switching of the PV input relay will affect the service life and generate noise, so the weak photovoltaic identification circuit is indispensable.

[0003] The traditional weak photovoltaic identification circuit only relies on the release of current by the cement resistor, and has disadvantages. When the PV voltage changes, the current will be unstable, which makes it difficult to select the type of cement resistor and the wire diameter selection of the PCB layout (printed circuit board layout design). CONTENT OF THE INVENTION

[0004] The embodiment of the present application provides a pre-charging circuit and an energy storage power supply, which can reduce the inrush current in the initial stage of capacitor charging, and at the same time, can realize smooth transition from pre-charging to normal power supply, and improves the safety and stability of the circuit.

[0005] In a first aspect, the embodiment of the present application provides a pre-charging circuit. The pre-charging circuit includes a constant current driving module, a pre-charging switch module, a power supply switch module and a voltage conversion module. The constant current driving module is connected with the pre-charging switch module and a photovoltaic power supply respectively, the pre-charging switch module is further connected with the voltage conversion module, and the power supply switch module is connected with the photovoltaic power supply and the voltage conversion module respectively. The constant current driving module is used to output a constant current signal when the input voltage of the photovoltaic power supply is greater than or equal to a first preset voltage, so as to drive the pre-charging switch module to work, and then make the photovoltaic power supply pre-charge a capacitor in the voltage conversion module through the pre-charging switch module; the power supply switch module is used to conduct when the voltage of the capacitor is greater than a preset value, so as to make the photovoltaic power supply supply power to the voltage conversion module through the power supply switch module.

[0006] In some embodiments, the pre-charging circuit further includes a control module. The control module is connected with the constant current driving module. The control module is used to control the constant current driving module to stop working when the voltage of the capacitor is greater than the preset value.

[0007] In some embodiments, the control module includes a resistor R3 and a switch tube Q2. The first end of the resistor R3 is connected with the control unit, the control end of the switch tube Q2 is connected with the second end of the resistor R3, the first end of the switch tube Q2 is connected with the constant current driving module, and the second end of the switch tube Q2 is grounded.

[0008] In some embodiments, the constant current driving module comprises a resistor R2, a Zener diode DZ1, a switch tube Q1 and a resistor R5. A first end of the resistor R2 is connected with the photovoltaic power supply, a second end of the resistor R2 is connected with a negative electrode of the Zener diode DZ1 and a control end of the switch tube Q1 respectively, a first end of the switch tube Q1 is connected with the photovoltaic power supply, a second end of the switch tube Q1 is connected with a first end of the resistor R5 and the pre-charge switch module respectively, and a second end of the resistor R5 and a positive electrode of the Zener diode DZ1 are grounded.

[0009] In some embodiments, the constant current driving module further comprises a diode D1. A positive electrode of the diode D1 is connected with the second end of the switch tube Q1, and a negative electrode of the diode D1 is connected with the pre-charge switch module.

[0010] In some embodiments, the constant current driving module further comprises a capacitor C1. A first end of the capacitor C1 is connected with the negative electrode of the diode D1, and a second end of the capacitor C1 is grounded.

[0011] In some embodiments, the pre-charge switch module comprises a relay RLY2 and a resistor RT1. A first coil pin of the relay RLY2 is connected with the constant current driving module, a second coil pin of the relay RLY2 is grounded, a first contact pin of the relay RLY2 is connected with the photovoltaic power supply, a second contact pin of the relay RLY2 is connected with a first end of the resistor RT1, and a second end of the resistor RT1 is connected with the voltage conversion module.

[0012] In some embodiments, the pre-charge circuit further comprises an under-voltage detection module. The under-voltage detection module is connected with the photovoltaic power supply and the control module respectively. The under-voltage detection module is used to output an under-voltage signal when an input voltage of the photovoltaic power supply is less than or equal to a second preset voltage, so as to drive the control module to work, thereby making the control module control the constant current driving module to stop working.

[0013] In some embodiments, the under-voltage detection module comprises a resistor R1 and a resistor R4. A first end of the resistor R1 is connected with the photovoltaic power supply, a second end of the resistor R1 is connected with a first end of the resistor R4 and the control module respectively, and a second end of the resistor R4 is grounded.

[0014] In a second aspect, the embodiments of the present application provide a storage power supply, which comprises the pre-charge circuit as described above.

[0015] Different from the prior art, the embodiment of the present application provides a pre-charging circuit and an energy storage power supply. In the pre-charging circuit and the energy storage power supply provided by the embodiment of the present application, when the input voltage of the photovoltaic power supply is greater than or equal to a first preset voltage, the constant current driving module outputs a constant current signal to drive the pre-charging switch module to work, so that the photovoltaic power supply performs constant current pre-charging on the capacitor in the voltage conversion module through the pre-charging switch module, and the voltage of the capacitor gradually rises. When the voltage of the capacitor is greater than a preset value, the power supply switch module is turned on, and the photovoltaic power supply supplies power to the voltage conversion module through the power supply switch module. The embodiment of the present application avoids the inrush current in the initial charging of the capacitor through constant current pre-charging, reduces the damage to the circuit elements, and improves the safety of the circuit. At the same time, the smooth transition from pre-charging to normal power supply can be realized, the voltage conversion module can work stably, and the stability of the circuit is improved. BRIEF DESCRIPTION OF DRAWINGS

[0016] One or more embodiments are illustrated by way of example with reference to the accompanying drawings, which are schematic and not intended to be limiting of the embodiments, and in which like reference numerals designate similar items in the figures, and in which:

[0017] Figure 1 is a structural block diagram of a pre-charging circuit provided by an embodiment of the present application;

[0018] Figure 2 is a structural block diagram of a pre-charging circuit provided by another embodiment of the present application;

[0019] Figure 3 is a circuit structure schematic diagram of a pre-charging circuit provided by an embodiment of the present application. DETAILED DESCRIPTION

[0020] In order to make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are some but not all of the embodiments of the present application. It should be understood that the specific embodiments described herein are only used to explain the present application and should not be used to limit the present application.

[0021] The technical features involved in the various embodiments of the present application described below do not conflict with each other and can be combined with each other.

[0022] When an element is described as "connected to" another element, it can be directly connected to the other element, or one or more intermediate elements can be present therebetween.

[0023] The terms "first", "second", etc. in the specification and claims of the present application are used to distinguish similar objects, and are not used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances, so that the embodiments of the present application can be implemented in an order other than those illustrated or described herein, and the objects distinguished by "first", "second", etc. are generally a class, not limited to the number of objects, for example, the first object can be one or more.

[0024] Please refer to Figure 1 , Figure 1 is a structure block diagram of the pre-charge circuit 100 provided by an embodiment of the present application.

[0025] An embodiment of the present application provides a pre-charge circuit 100, which comprises a constant current driving module 11, a pre-charge switch module 12, a power supply switch module 13 and a voltage conversion module 14.

[0026] The constant current driving module 11 is connected with the pre-charge switch module 12 and the photovoltaic power supply 200 respectively, the pre-charge switch module 12 is further connected with the voltage conversion module 14, and the power supply switch module 13 is connected with the photovoltaic power supply 200 and the voltage conversion module 14 respectively.

[0027] Specifically, the constant current driving module 11 is configured to output a constant current signal when the input voltage of the photovoltaic power supply 200 is greater than or equal to a first preset voltage, so as to drive the pre-charge switch module 12 to work, and then make the photovoltaic power supply 200 pre-charge the capacitor in the voltage conversion module 14 through the pre-charge switch module 12. The power supply switch module 13 is configured to be turned on when the voltage of the capacitor is greater than a preset value, so as to make the photovoltaic power supply 200 supply power to the voltage conversion module 14 through the power supply switch module 13.

[0028] The first preset voltage is a threshold voltage, which is used to trigger the constant current driving module 11 to start working. It is determined according to the overall design requirements of the pre-charge circuit and the characteristics of the photovoltaic power supply 200. In the working process of the photovoltaic power supply 200, its output voltage will fluctuate with factors such as light intensity and temperature. When the input voltage of the photovoltaic power supply 200 rises to be greater than or equal to the first preset voltage, it means that the power output reaches a level that can meet the pre-charge starting condition. The value of the first preset voltage is related to the capacitor capacity in the voltage conversion module 14, the working characteristics of the constant current driving module 11 and the speed requirements of the pre-charge, etc.

[0029] The constant current signal is a current signal output by the constant current driving module 11, and has the characteristic that the current is relatively constant in a certain time. When the constant current driving module 11 is triggered to work (i.e., the input voltage of the photovoltaic power supply 200 is greater than or equal to the first preset voltage), it will generate a constant current signal to drive the pre-charging switch module 12. During the pre-charging process, the constant current signal passes through the pre-charging switch module 12 to charge the capacitor in the voltage conversion module 14 by the photovoltaic power supply 200. Because the current is constant, according to the charging characteristics of the capacitor, the voltage across the capacitor will rise in a certain linear rule, avoiding the damage to the capacitor and other circuit elements caused by the inrush current that may occur at the initial stage of charging.

[0030] The preset value refers to a specific value of the voltage across the capacitor, which is used to trigger the power supply switch module 13 to conduct, so that the circuit switches from the pre-charging stage to the normal power supply stage. In the pre-charging stage, the capacitor in the voltage conversion module 14 is charged through the pre-charging switch module 12, and its voltage gradually rises. When the capacitor voltage reaches the preset value, the power supply switch module 13 detects this voltage change, and the internal trigger mechanism (such as a voltage comparator) makes the power supply switch module 13 conductive. In this way, the photovoltaic power supply 200 can supply power to the voltage conversion module 14 through the power supply switch module 13, realizing a smooth transition from pre-charging to normal power supply.

[0031] In actual application, when the input voltage of the photovoltaic power supply 200 rises to be greater than or equal to the first preset voltage, the constant current driving module 11 starts to work. Then, the constant current driving module 11 will generate a stable constant current signal based on the internal constant current source circuit. The constant current signal output by the constant current driving module 11 acts on the pre-charging switch module 12. Under the drive of the constant current signal, the pre-charging switch module 12 is conductive, thereby establishing a path between the photovoltaic power supply 200 and the capacitor in the voltage conversion module 14. At this time, the photovoltaic power supply 200 starts to charge the capacitor in the voltage conversion module 14 through the pre-charging switch module 12. The voltage across the capacitor in the voltage conversion module 14 will gradually rise. When the voltage across the capacitor is greater than the preset value, the power supply switch module 13 starts to work, and the power supply switch module 13 is conductive. At this time, the photovoltaic power supply 200 is connected with the voltage conversion module 14 through the power supply switch module 13, and starts to supply power to the voltage conversion module 14. After the power supply switch module 13 is conductive, the circuit enters the normal power supply state. At this time, the photovoltaic power supply 200 mainly provides power to the voltage conversion module 14 through the power supply switch module 13. The voltage conversion module 14 will perform voltage conversion processing on the input photovoltaic power supply according to the internal circuit structure (for example, containing a boost circuit).

[0032] Please refer to Figure 2 , Figure 2 is a structural block diagram of the pre-charging circuit 100 provided by another embodiment of the application.

[0033] In some embodiments, the pre-charge circuit 100 further comprises a control module 15. Wherein, the control module 15 is connected with the constant current driving module 11. Specifically, the control module 15 is used to control the constant current driving module 11 to stop working when the voltage of the capacitor is greater than the preset value.

[0034] In this embodiment, during the charging process of the capacitor in the voltage conversion module 14, the voltage continues to rise. When the voltage of the capacitor is greater than the preset value, two actions will be taken. First, the voltage comparison circuit or trigger mechanism inside the power supply switch module 13 will detect that the voltage of the capacitor reaches the preset value, so that the power supply switch module 13 is turned on. At this time, the photovoltaic power supply 200 is connected with the voltage conversion module 14 through the power supply switch module 13, and starts to supply power to the voltage conversion module 14. At the same time, the control module 15 will also detect that the voltage of the capacitor is greater than the preset value. The control module 15 will send a control signal to the constant current driving module 11 to make the constant current driving module 11 stop working. The pre-charge process is completed, which avoids the energy loss or interference to the circuit caused by the continuous work of the constant current driving module 11.

[0035] In some embodiments, the pre-charge circuit 100 further comprises an under-voltage detection module 16. Wherein, the under-voltage detection module 16 is connected with the photovoltaic power supply 200 and the control module 15 respectively. Specifically, the under-voltage detection module 16 is used to output an under-voltage signal to drive the control module 15 to work when the input voltage of the photovoltaic power supply 200 is less than or equal to the second preset voltage, so as to make the control module 15 control the constant current driving module 11 to stop working.

[0036] Wherein, the second preset voltage is a threshold value for judging whether the input voltage of the photovoltaic power supply 200 is too low. It is a key parameter of the under-voltage protection mechanism in the pre-charge circuit 100. Its value mainly depends on the minimum working voltage of the constant current driving module 11, the characteristics of the photovoltaic power supply 200, and the voltage tolerance of other elements in the pre-charge circuit, etc. By adjusting the parameters of the elements in the under-voltage detection module 16, the value of the second preset voltage can be adjusted.

[0037] The under-voltage signal is a control signal output by the under-voltage detection module 16 when it detects that the input voltage of the photovoltaic power supply 200 is less than or equal to the second preset voltage. The specific characteristics (such as signal type, level range, pulse characteristics, etc.) of the under-voltage signal depend on the interface circuit design between the under-voltage detection module 16 and the control module 15. In the pre-charge circuit, the under-voltage signal is mainly used to trigger the control module 15 to perform corresponding operations, that is, to control the constant current driving module 11 to stop working, so as to avoid the circuit failure caused by continuing to pre-charge in the low voltage condition, and to play a role in protecting the circuit.

[0038] In this embodiment, the under-voltage detection module 16 always monitors the input voltage of the photovoltaic power supply 200. When the input voltage of the photovoltaic power supply 200 drops to less than or equal to the second preset voltage, the under-voltage detection module 16 outputs an under-voltage signal. The under-voltage signal drives the control module 15 to work, and after the control module 15 receives the under-voltage signal, it controls the constant current driving module 11 to stop working. This is a protection mechanism because when the voltage of the photovoltaic power supply 200 is too low, the pre-charging may not be able to proceed normally, or even the circuit components may be damaged, at which time the work of the constant current driving module 11 can be stopped to protect the circuit.

[0039] Referring to Figure 3 , Figure 3 is a circuit structure schematic diagram of the pre-charging circuit 100 provided in an embodiment of the present application.

[0040] In some embodiments, the constant current driving module 11 includes a resistor R2, a zener diode DZ1, a switch tube Q1, and a resistor R5. The first end of the resistor R2 is connected with the photovoltaic power supply 200, the second end of the resistor R2 is connected with the negative electrode of the zener diode DZ1 and the control end of the switch tube Q1 respectively, the first end of the switch tube Q1 is connected with the photovoltaic power supply 200, the second end of the switch tube Q1 is connected with the first end of the resistor R5 and the pre-charging switch module 12 respectively, and the second end of the resistor R5 and the positive electrode of the zener diode DZ1 are both grounded.

[0041] The switch tube Q1 can be an NPN triode or any other suitable switch tube. Taking the switch tube Q1 as an NPN triode as an example, the control end of the switch tube Q1 is the base of the NPN triode, the first end of the switch tube Q1 is the collector of the NPN triode, and the second end of the switch tube Q1 is the emitter of the NPN triode.

[0042] Specifically, when the photovoltaic power supply 200 is connected to the PV_IN, the input voltage of the photovoltaic power supply 200 is greater than or equal to the first preset voltage, and the zener diode DZ1 reaches the reverse breakdown voltage (zener value). At this time, the zener diode DZ1 is turned on, so that the control end of the switch tube Q1 obtains sufficient voltage, and the switch tube Q1 is turned on. At this time, the photovoltaic power supply 200 outputs current to the pre-charging switch module 12 through the turned-on switch tube Q1. This current path is from the photovoltaic power supply 200 through the first end (collector) of the switch tube Q1, and then flows out from the second end (emitter) of the switch tube Q1 through the resistor R5. The resistor R5 plays a key constant current role in this circuit. When the switch tube Q1 is turned on, the emitter voltage of the switch tube Q1 is approximately equal to the voltage across the resistor R5 (ignoring the emitter junction voltage drop of the switch tube Q1). In the case where the switch tube Q1 is turned on, the current flowing through the resistor R5 is basically constant, thereby generating a constant current signal.

[0043] In some embodiments, the constant current driving module 11 further comprises a diode D1. Wherein, the positive pole of the diode D1 is connected with the second end of the switch tube Q1, and the negative pole of the diode D1 is connected with the pre-charge switch module 12.

[0044] Specifically, the diode D1 is used to prevent backflow.

[0045] In some embodiments, the constant current driving module 11 further comprises a capacitor C1. Wherein, the first end of the capacitor C1 is connected with the negative pole of the diode D1, and the second end of the capacitor C1 is grounded.

[0046] Specifically, the capacitor C1 is used for voltage stabilization and filtering.

[0047] In some embodiments, the pre-charge switch module 12 comprises a relay RLY2 and a resistor RT1. Wherein, the first coil pin of the relay RLY2 is connected with the constant current driving module 11, the second coil pin of the relay RLY2 is grounded, the first contact pin of the relay RLY2 is connected with the photovoltaic power supply 200, the second contact pin of the relay RLY2 is connected with the first end of the resistor RT1, and the second end of the resistor RT1 is connected with the voltage conversion module 14.

[0048] Specifically, when the constant current driving module 11 outputs a constant current signal, the current will flow into the first coil pin of the relay RLY2. Since the second coil pin of the relay RLY2 is grounded, a complete circuit is formed, so that the current passes through the coil of the relay RLY2. When the current passes through the coil, the coil of the relay RLY2 generates a magnetic field, which causes the contacts of the relay RLY2 to act. With the action of the contacts of the relay RLY2, the path between the first contact pin (connected with the photovoltaic power supply 200) and the second contact pin (connected with the first end of the resistor RT1) is turned on. From the second end of the resistor RT1, the circuit is connected to the capacitor in the voltage conversion module 14, thereby establishing a path for the photovoltaic power supply 200 to charge the capacitor in the voltage conversion module 14. At this time, the capacitor starts to charge, and since the constant current driving module 11 provides a basically constant current, the capacitor will be charged at a relatively stable rate, avoiding damage to the capacitor and other circuit elements caused by inrush current.

[0049] The resistor RT1 has certain current limiting and buffering effects in this circuit. On the one hand, it can limit the excessive current that may occur during pre-charging, although the constant current driving module 11 has controlled the current size to some extent, the resistor RT1 can serve as an additional protection measure. On the other hand, during the charging process of the capacitor, if current fluctuations or other abnormal situations occur, the resistor RT1 can consume part of the energy, acting as a buffer, which helps to maintain the relative stability of the charging process.

[0050] In some embodiments, the power supply switch module 13 comprises a relay RLY1. Wherein, the first coil pin of the relay RLY1 and the second coil pin of the relay RLY1 are both connected with a control unit (not shown in the figure), the first contact pin of the relay RLY1 is connected with the photovoltaic power supply 200, and the second contact pin of the relay RLY1 is connected with the voltage conversion module 14.

[0051] Wherein, the control unit is used to output a current signal when the voltage of the capacitor CE2 is greater than a preset value, and drive the relay RLY1 to be turned on.

[0052] In some embodiments, the voltage conversion module 14 comprises a capacitor CE1, a capacitor CE2, a capacitor CE3, an inductor LD1, a switch tube Q3 and a switch tube Q4. Wherein, the positive pole of the capacitor CE2 is connected with the positive pole of the capacitor CE3, the first end of the inductor LD1, the pre-charge switch module 12 and the power supply switch module 13 respectively, the second end of the inductor LD1 is connected with the first end of the switch tube Q3 and the first end of the switch tube Q4 respectively, the second end of the switch tube Q3 is connected with the positive pole and the negative pole of the capacitor CE1 and the load (not shown in the figure) respectively, and the negative pole of the capacitor CE2, the negative pole of the capacitor CE3, the second end of the switch tube Q4 and the negative pole of the capacitor CE1 are all grounded.

[0053] Specifically, the capacitor CE2 and / or the capacitor CE3 are pre-charge objects of the pre-charge circuit 100.

[0054] Wherein, the switch tube Q3 and the switch tube Q4 can be PMOS tubes or any other suitable switch tubes. Taking the switch tube Q3 as a PMOS tube as an example, the control end of the switch tube Q3 is the gate of the PMOS tube, the first end of the switch tube Q3 is the source of the PMOS tube, and the second end of the switch tube Q3 is the drain of the PMOS tube. Taking the switch tube Q4 as a PMOS tube as an example, the control end of the switch tube Q4 is the gate of the PMOS tube, the first end of the switch tube Q4 is the drain of the PMOS tube, and the second end of the switch tube Q4 is the source of the PMOS tube.

[0055] In some embodiments, the control module 15 comprises a resistor R3 and a switch tube Q2. Wherein, the first end of the resistor R3 is connected with the control unit, the control end of the switch tube Q2 is connected with the second end of the resistor R3, the first end of the switch tube Q2 is connected with the constant current drive module 11, and the second end of the switch tube Q2 is grounded.

[0056] Wherein, the switch tube Q2 can be a PNP transistor or any other suitable switch tube. Taking the switch tube Q2 as a PNP transistor as an example, the control end of the switch tube Q2 is the base of the PNP transistor, the first end of the switch tube Q2 is the emitter of the PNP transistor, and the second end of the switch tube Q2 is the collector of the PNP transistor.

[0057] The control unit is configured to output a control signal (e.g., a low-level signal) when the voltage of the capacitor CE2 is greater than a preset value. Then, the switch tube Q2 is turned on, and then the switch tube Q1 is turned off, so as to control the constant current driving module 11 to stop working.

[0058] The control unit can be a simple logic circuit composed of comparators, NAND gates and other basic logic elements, which performs logical judgment according to various input signals (such as Figure 3 voltage signals across the capacitor CE2, etc.), and outputs signals (current signals) for controlling the relay coil and signals (control signals) for controlling the switch tube Q2. The control unit can also be a microcontroller (such as a single-chip microcomputer), which realizes more complex control logic through programming. For example, the control unit can flexibly control different working modes and fault states, and can communicate with other circuit modules to realize more advanced system functions.

[0059] In some embodiments, the under-voltage detection module 16 includes a resistor R1 and a resistor R4. The first end of the resistor R1 is connected to the photovoltaic power supply 200, the second end of the resistor R1 is connected to the first end of the resistor R4 and the control module 15 respectively, and the second end of the resistor R4 is grounded.

[0060] Specifically, by adjusting the resistance values of the resistor R1 and the resistor R4, the value of the second preset voltage can be adjusted. Generally, the second preset voltage is less than the first preset voltage.

[0061] The working principle of the pre-charge circuit 100 will be briefly described below. Figure 2 and Figure 3

[0062] Firstly, when the photovoltaic power supply 200 starts to work, its voltage gradually rises. When the input voltage of the photovoltaic power supply 200 (the voltage at PV_IN) is greater than or equal to the first preset voltage, in the constant current driving module 11, the current passes through the resistor R2, so that the zener diode DZ1 reaches the reverse breakdown voltage (zener voltage) and is turned on. The conduction of the zener diode DZ1 enables the control end of the switch tube Q1 to obtain sufficient voltage to drive the switch tube Q1 to turn on.

[0063] Secondly, after the switch tube Q1 is turned on, the photovoltaic power supply 200 outputs current to the pre-charge switch module through the switch tube Q1. The current passes through the resistor R5, and since the voltage across the resistor R5 is relatively stable, the current passing through the resistor R5 is basically constant, thereby generating a constant current signal. The diode D1 is used to prevent reverse current flow, and the capacitor C1 serves as a filter to reduce the influence of voltage fluctuations on the constant current signal.

[0064] ​Then, the constant current signal outputted by the constant current driving module 11 enters the first coil pin of the relay RLY2 of the pre-charge switch module 12. Since the second coil pin is grounded, a loop is formed to make the coil of the relay RLY2 energized. According to the principle of electromagnetic induction, the contacts of the relay RLY2 act to make the path between the first contact pin (connected with the photovoltaic power supply 200) and the second contact pin (connected with the resistor RT1) connected. The photovoltaic power supply 200 is connected with the capacitors (such as the capacitor CE2 and the capacitor CE3) in the voltage conversion module 14 through the relay RLY2 and the resistor RT1, and starts to pre-charge the capacitors. The resistor RT1 plays a role of current limiting and buffering, avoiding excessive current in the pre-charge moment.

[0065] Then, in the pre-charge stage, the photovoltaic power supply 200 continuously charges the capacitors (such as the capacitor CE2 and the capacitor CE3) in the voltage conversion module 14 through the pre-charge switch module 12. The voltage across the capacitors gradually rises, and since the charging current is constant, the capacitor voltage rises steadily, avoiding damage to the capacitors and other circuit elements by inrush current.

[0066] Then, when the voltage of the capacitor is greater than the preset value, at the same time, the power supply switch module 13 detects that the capacitor voltage is greater than the preset value and is turned on (the relay RLY1 is turned on), the photovoltaic power supply 200 is connected with the voltage conversion module 14 through the power supply switch module 13, and starts to supply power to the voltage conversion module 14. At the same time, in the control module 15, the control unit applies a voltage (such as a low level) to the control end of the switch tube Q2 through the resistor R3, so that the switch tube Q2 is turned on. After the switch tube Q2 is turned on, the switch tube Q1 in the constant current driving module 11 stops working, thereby stopping outputting the constant current signal, and the pre-charge process ends. At this time, the capacitors in the voltage conversion module 14 have been pre-charged and can provide stable initial energy for subsequent voltage conversion.

[0067] In addition, the under-voltage detection module 16 always monitors the input voltage of the photovoltaic power supply 200. When the input voltage of the photovoltaic power supply 200 drops to less than or equal to the second preset voltage, in the under-voltage detection module 16, an under-voltage signal is generated (for example, when the voltage after voltage division is lower than a certain threshold) through the voltage division of the resistors R1 and R4. This under-voltage signal is transmitted to the switch tube Q2 of the control module 15 to drive the switch tube Q2 to be turned on. After the switch tube Q2 is turned on, the switch tube Q1 in the constant current driving module 11 stops working. Thus, it is avoided to continue pre-charging when the photovoltaic power supply voltage is too low, and the circuit elements are protected from being damaged.

[0068] After the power supply switch module 13 is turned on, the normal power supply stage is entered. The voltage conversion module 14 starts to work. Taking the boost converter as an example, when the switch tube Q4 is turned on and Q3 is turned off, the photovoltaic power supply forms a loop through the inductor LD1 and Q4, and the inductor LD1 stores energy. When Q4 is turned off and Q3 is turned on, the induced electromotive force generated by the inductor LD1 is superimposed with the photovoltaic power supply voltage, and the capacitor CE1 is charged and power is supplied to the load. The size of the output voltage is adjusted by controlling the on and off time (duty cycle) of the switch tubes Q3 and Q4. The capacitors CE1, CE2 and CE3 also have a filtering effect, smooth the output voltage, and reduce the voltage ripple to provide stable DC voltage for the load.

[0069] In the precharge circuit provided in the embodiments of the present application, when the input voltage of the photovoltaic power supply is greater than or equal to the first preset voltage, the constant current driving module outputs a constant current signal to drive the precharge switch module to work, so that the photovoltaic power supply precharges the capacitor in the voltage conversion module with constant current through the precharge switch module, and the voltage of the capacitor gradually rises. When the voltage of the capacitor is greater than the preset value, the power supply switch module is turned on, the photovoltaic power supply supplies power to the voltage conversion module through the power supply switch module, and at the same time, the constant current driving module can stop working. And when the input voltage of the photovoltaic power supply is less than or equal to the second preset voltage, the constant current driving module also stops working to protect the circuit. The embodiments of the present application avoid the inrush current in the initial charging of the capacitor by constant current precharging, reduce the damage to the circuit elements, and improve the safety of the circuit. At the same time, it can realize smooth transition from precharging to normal power supply, so that the voltage conversion module works stably, and the stability of the circuit is improved. An under-voltage protection mechanism is also provided to enhance the reliability and stability of the circuit, effectively utilize the photovoltaic power supply and prolong the service life of the circuit elements.

[0070] The embodiments of the present application also provide a storage power supply, which comprises the precharge circuit 100 as described above.

[0071] The specific structure and working principle of the precharge circuit 100 can refer to the above embodiments, which will not be described here.

[0072] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, but not to limit them; the technical features in the above embodiments or different embodiments can also be combined under the idea of the present application, and there are many other changes of different aspects of the present application as described above; for the sake of simplicity, they are not provided in details; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: the technical solutions recorded in the foregoing embodiments can still be modified, or some technical features can be replaced; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A pre-charging circuit, characterized in that, The pre-charging circuit includes a constant current drive module, a pre-charging switch module, a power supply switch module, and a voltage conversion module; The constant current drive module is connected to the precharge switch module and the photovoltaic power supply respectively. The precharge switch module is also connected to the voltage conversion module. The power supply switch module is connected to the photovoltaic power supply and the voltage conversion module respectively. The constant current drive module is used to output a constant current signal when the input voltage of the photovoltaic power supply is greater than or equal to a first preset voltage, so as to drive the precharge switch module to work, thereby enabling the photovoltaic power supply to precharge the capacitor in the voltage conversion module through the precharge switch module. The power supply switch module is used to turn on the capacitor when the voltage of the capacitor is greater than a preset value, so that the photovoltaic power supply can supply power to the voltage conversion module through the power supply switch module.

2. The pre-charging circuit according to claim 1, characterized in that, The pre-charging circuit also includes a control module; The control module is connected to the constant current drive module; The control module is used to control the constant current drive module to stop working when the voltage of the capacitor is greater than a preset value.

3. The pre-charging circuit according to claim 2, characterized in that, The control module includes a resistor R3 and a switching transistor Q2; The first end of the resistor R3 is connected to the control unit, the control terminal of the switch Q2 is connected to the second end of the resistor R3, the first end of the switch Q2 is connected to the constant current drive module, and the second end of the switch Q2 is grounded.

4. The pre-charging circuit according to claim 1, characterized in that, The constant current drive module includes a resistor R2, a Zener diode DZ1, a switching transistor Q1, and a resistor R5. The first end of the resistor R2 is connected to the photovoltaic power source, the second end of the resistor R2 is connected to the negative terminal of the Zener diode DZ1 and the control terminal of the switching transistor Q1, the first end of the switching transistor Q1 is connected to the photovoltaic power source, the second end of the switching transistor Q1 is connected to the first end of the resistor R5 and the precharge switch module, and the second end of the resistor R5 and the positive terminal of the Zener diode DZ1 are both grounded.

5. The pre-charging circuit according to claim 4, characterized in that, The constant current drive module also includes a diode D1; The positive terminal of diode D1 is connected to the second terminal of the switching transistor Q1, and the negative terminal of diode D1 is connected to the precharge switch module.

6. The pre-charging circuit according to claim 5, characterized in that, The constant current drive module also includes a capacitor C1; The first terminal of capacitor C1 is connected to the negative terminal of diode D1, and the second terminal of capacitor C1 is grounded.

7. The pre-charging circuit according to claim 1, characterized in that, The precharge switch module includes a relay RLY2 and a resistor RT1; The first coil pin of the relay RLY2 is connected to the constant current drive module, the second coil pin of the relay RLY2 is grounded, the first contact pin of the relay RLY2 is connected to the photovoltaic power supply, the second contact pin of the relay RLY2 is connected to the first end of the resistor RT1, and the second end of the resistor RT1 is connected to the voltage conversion module.

8. The pre-charging circuit according to claim 2 or 3, characterized in that, The pre-charging circuit also includes an undervoltage detection module; The undervoltage detection module is connected to both the photovoltaic power supply and the control module. The undervoltage detection module is used to output an undervoltage signal when the input voltage of the photovoltaic power supply is less than or equal to a second preset voltage, so as to drive the control module to work, thereby causing the control module to control the constant current drive module to stop working.

9. The pre-charging circuit according to claim 8, characterized in that, The undervoltage detection module includes resistors R1 and R4; The first end of the resistor R1 is connected to the photovoltaic power source, the second end of the resistor R1 is connected to the first end of the resistor R4 and the control module, and the second end of the resistor R4 is grounded.

10. An energy storage power source, characterized in that, The energy storage power supply includes a pre-charging circuit as described in any one of claims 1 to 9.

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