Dry contact input signal protection circuit, dry contact equipment and distributed photovoltaic system

Abstract

The utility model relates to the technical field of dry contact equipment protection, and discloses a dry contact input signal protection circuit, dry contact equipment and a distributed photovoltaic system, the dry contact input signal protection circuit is applied to the dry contact equipment, and an input end of a power supply current-limiting and surge protection circuit is connected with a power supply end of voltage output; the output end of the power supply current-limiting and surge protection circuit is connected with the signal input end of the dry contact equipment; the input end of the surge protection circuit is connected with the signal output end of the dry contact equipment; the signal output end of the dry contact device is sequentially connected with the signal isolation circuit, the level conversion circuit, the voltage clamping circuit and the MCU. According to the utility model, the direct connection state of the dry contact equipment is protected, and the problem that the dry contact equipment is directly and externally connected with outdoor or high-voltage power supply equipment in a non-isolated state and the equipment is damaged due to surge is avoided.

Description

TECHNICAL FIELD

[0001] The utility model belongs to dry contact equipment protection technical field, especially related to a dry contact input signal protection circuit, dry contact equipment and distributed photovoltaic system. BACKGROUND

[0002] With the continuous development of photovoltaic, energy storage industry, especially household photovoltaic. Household photovoltaic is a form of distributed photovoltaic, mainly refers to the installation and use of distributed solar power generation system in the family own roof or courtyard, usually small scale, not through the battery energy storage, but is directly through the grid-connected inverter to input the public power grid, more and more families begin to choose to install household photovoltaic system, to realize self-sufficient energy supply and reduce the dependence on traditional energy, in the global range, the household photovoltaic market all shows the vigorous development momentum.

[0003] One of the core equipment of household energy management equipment of household photovoltaic power generation energy management system, can unified scheduling and management to household energy, realizes the efficient use of energy, and supports the access of charging pile, SGReady heat pump, intelligent switch and other intelligent power utilization equipment, many in the equipment are dry contact communication mode, directly connected with household energy management equipment. But this kind of direct external connection outdoor or high voltage power supply equipment may cause the problem of damaging the equipment due to surge. UTILITY MODEL CONTENT

[0004] The utility model aims at providing a kind of dry contact input signal protection circuit, dry contact equipment and distributed photovoltaic system, to overcome the defect that dry contact equipment is directly connected with energy management equipment, causes the damage of equipment due to surge. Specific technical scheme is as follows:

[0005] A kind of dry contact input signal protection circuit, applied in dry contact equipment, protection circuit includes power supply current limiting and surge protection circuit, surge protection circuit, signal isolation circuit, level conversion circuit, voltage clamping circuit and MCU;

[0006] The input end of the power supply current limiting and surge protection circuit is connected with the power supply end of voltage output, and the output end of the power supply current limiting and surge protection circuit is connected with the signal input end of dry contact equipment;The input end of the surge protection circuit is connected with the signal output end of the dry contact equipment;The output end of the surge protection circuit is connected with signal isolation circuit, level conversion circuit, voltage clamping circuit and MCU in turn.

[0007] Preferably, the power supply current limiting and surge protection circuit comprises a first diode and a current limiting resistor; one end of the current limiting resistor is connected to a power supply end, and the other end of the current limiting resistor is connected to a signal input end of the dry contact device; one end of the first diode is grounded, and the other end of the first diode is connected to the signal input end of the dry contact device.

[0008] Preferably, the surge protection circuit comprises a second diode and a transient voltage suppressor in parallel; one end of the parallel connection of the second diode and the transient voltage suppressor is connected to a signal output end of the dry contact device, and the other end of the parallel connection of the second diode and the transient voltage suppressor is grounded.

[0009] Preferably, the protection circuit further comprises a terminal; the other end of the current limiting resistor and the other end of the first diode are connected to a first terminal port of the terminal, the first terminal port of the terminal is connected to the signal input end of the dry contact device; one end of the parallel connection of the second diode and the transient voltage suppressor is connected to a second terminal port of the terminal, and the second terminal port of the terminal is connected to the signal output end of the dry contact device.

[0010] Preferably, the signal isolation circuit comprises a first resistor, a second resistor and an operational amplifier; the second terminal port of the terminal is connected to a non-inverting input end of the operational amplifier through the first resistor; one end of the second resistor is connected to an inverting input end of the operational amplifier, and the other end of the second resistor is connected to an output end of the operational amplifier; the operational amplifier is further connected to a ground and a power supply end of a working voltage respectively.

[0011] Preferably, the level conversion circuit comprises a third resistor, a fourth resistor and a transistor; the output end of the operational amplifier is connected to a base of the transistor through the third resistor; an emitter of the transistor is grounded; a collector of the transistor is connected to the power supply end of the working voltage through the fourth resistor.

[0012] Preferably, the voltage clamping circuit comprises a fifth resistor, a first unidirectional diode and a second unidirectional diode; one end of the fifth resistor is connected to the collector of the transistor, and the other end of the fifth resistor is connected to an anode of the first unidirectional diode, a cathode of the second unidirectional diode and a signal input end of the MCU respectively; a cathode of the first unidirectional diode is connected to the power supply end of the working voltage under; and an anode of the second unidirectional diode is grounded.

[0013] A dry contact device comprising a dry contact input signal protection circuit according to the foregoing.

[0014] A distributed photovoltaic system comprising the dry contact device according to the foregoing.

[0015] Compared with the prior art, the utility model has the advantages of the following:

[0016] The utility model discloses a dry contact input signal protection circuit, be applied to dry contact equipment, through the input end voltage output power end of power current -limiting and surge protection circuit's connection, power current -limiting and the output of surge protection circuit's connection dry contact equipment's signal input end, the input end of surge protection circuit connects the signal output end of dry contact equipment, the signal output end of dry contact equipment connects signal isolation circuit, level conversion circuit, voltage clamping circuit and MCU in proper order. BRIEF DESCRIPTION OF DRAWINGS

[0017] In order to more clearly illustrate the technical scheme of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiment description. In all the drawings, similar elements or parts are generally identified by similar reference signs. In the drawings, each element or part is not necessarily drawn according to the actual proportion.

[0018] Figure 1 It is the dry contact input signal protection circuit composition schematic diagram of the utility model.

[0019] Figure 2 It is the dry contact input signal protection circuit connection schematic diagram of the utility model.

[0020] Figure 3 It is the composition schematic diagram of dry contact equipment of the utility model.

[0021] Figure 4 It is the composition schematic diagram of distributed photovoltaic system of the utility model. DETAILED DESCRIPTION

[0022] The technical scheme in the embodiments of the utility model will be described clearly and completely in combination with the drawings in the embodiments of the utility model. Obviously, the described embodiments are only a part of the embodiments of the utility model, not all the embodiments. Based on the embodiments in the utility model, all the other embodiments obtained by the ordinary skilled in the art without creative labor are within the scope of protection of the utility model.

[0023] In the description of the utility model, it is necessary to explain that the orientation or positional relation indicated by the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "top", "bottom", "top surface", "bottom surface", "inner", "outer", "inner side", "outer side" is the orientation or positional relation shown in the drawings, and is only for the convenience of describing the utility model and simplifying the description, and therefore cannot be understood as a limitation on the utility model.

[0024] In the description of the utility model, the meaning of several is one or more, the meaning of multiple is more than two, greater than, less than, more than, etc.

[0025] In the description of the utility model, it is necessary to explain that, unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connection", "setting" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected, it can be mechanically connected, or it can be electrically connected, it can be directly connected, or it can be indirectly connected through an intermediate medium, it can be the communication between two elements. For ordinary skilled in the art, the specific meaning of the above terms in the utility model can be understood according to the specific circumstances. The embodiments of the utility model will be described below according to the overall structure.

[0026] The following embodiments please refer to Figures 1 to 4 .

[0027] The application embodiment provides a dry contact input signal protection circuit, which is applied to a dry contact device, and the protection circuit comprises a power current limiting and surge protection circuit, a surge protection circuit, a signal isolation circuit, a level conversion circuit, a voltage clamping circuit and an MCU.

[0028] The input end of the power current limiting and surge protection circuit is connected with the power supply end of voltage output, and the output end of the power current limiting and surge protection circuit is connected with the signal input end of the dry contact device; the input end of the surge protection circuit is connected with the signal output end of the dry contact device; the output end (also the signal output end of the dry contact device) of the surge protection circuit is connected with the signal isolation circuit, the level conversion circuit, the voltage clamping circuit and the MCU in sequence.

[0029] The working principle of the dry contact input signal protection circuit of the embodiment is as follows: the terminal J1 / 2 pin is connected to an external dry contact device to form a loop, and the loop is formed as follows: the power current limiting surge protection circuit→the first terminal port 1 of the terminal J1→the dry contact device→the second terminal port 2 of the terminal J1→the surge protection circuit→the signal isolation circuit→the level conversion circuit→the voltage clamping protection circuit→the MCU. When the terminal J1 is not connected to the dry contact device, the entire circuit loop is in an open state, and the MCU detects a high level; when the terminal J1 is connected to the dry contact device, the entire circuit loop is in a working state, and the MCU detects a low level.

[0030] Referring to Figure 2 , specifically, the power current limiting and surge protection circuit comprises a first secondary discharge tube DS1 and a current limiting resistor R1; one end of the current limiting resistor R1 is connected to a power supply end, and the other end of the current limiting resistor R1 is connected to a signal input end of the dry contact device; one end of the first secondary discharge tube DS1 is grounded, and the other end of the first secondary discharge tube DS1 is connected to the signal input end of the dry contact device.

[0031] In the embodiment, the power current limiting and surge protection circuit is composed of the current limiting resistor R1 and the first secondary discharge tube DS1 and is connected to the first terminal port 1 of the terminal J1, for providing voltage output for the entire dry contact input signal loop. The first secondary discharge tube DS1 is connected between the terminal J1 and the power current limiting resistor R1 to form a surge protection circuit, for preventing overcurrent and overvoltage signals generated from the first terminal port 1 of the terminal J1 from damaging the power current limiting circuit and the subsequent circuit.

[0032] Referring to Figure 2 , specifically, the surge protection circuit comprises a second secondary discharge tube DS2 and a transient suppression diode D2 connected in parallel; one end of the parallel connection of the second secondary discharge tube DS2 and the transient suppression diode D2 is connected to a signal output end of the dry contact device, and the other end of the parallel connection of the second secondary discharge tube DS2 and the transient suppression diode D2 is grounded.

[0033] In the embodiment, the secondary discharge tube is in a high resistance state and is not conductive under normal working voltage. However, when the surge voltage exceeds the breakdown voltage, the secondary discharge tube rapidly conducts to guide the surge current to the ground, thereby protecting the dry contact device and the subsequent circuit from damage caused by the surge. The transient suppression diode D2 can conduct in both directions. When an excessively high positive voltage or negative voltage appears at the signal output end of the dry contact device, the transient suppression diode D2 can rapidly conduct to clamp the excessively high voltage within a safe range, thereby avoiding damage to the dry contact device and other connected circuit elements.

[0034] The secondary discharge tube mainly discharges high amplitude surge voltage, while the transient suppression diode D2 focuses on clamping small amplitude overvoltage that may occur frequently. This combination of the two in parallel ensures that both large amplitude surge voltage and small amplitude overvoltage can be effectively handled, enhancing the circuit's protection against voltage abnormalities and ensuring the stability of the dry contact device. The second terminal port 2 of the terminal J1 is connected to the surge protection circuit, which prevents surge overcurrent and overvoltage signals from damaging the subsequent devices through the terminal J1, and then to the signal isolation circuit. The circuit realizes signal isolation between the input signal and the output signal through a follower.

[0035] Please refer to Figure 2 , specifically, the protection circuit further comprises a terminal J1; the other end of the current limiting resistor R1 and the other end of the first secondary discharge tube DS1 are connected to the first terminal port 1 of the terminal J1, and the first terminal port 1 of the terminal J1 is connected to the signal input end of the dry contact device; the parallel connection end of the second secondary discharge tube DS2 and the transient suppression diode D2 is connected to the second terminal port 2 of the terminal J1, and the second terminal port 2 of the terminal J1 is connected to the signal output end of the dry contact device.

[0036] In this embodiment, the terminal J1 serves as an intermediate connection interface, which can facilitate the connection of the dry contact device and the protection circuit. For example, when installing or replacing the dry contact device, only plugging or reconnection operation through the terminal J1 is needed, without the need for complex re-wiring of the entire protection circuit.

[0037] The two terminal ports are respectively connected to the signal input end and output end of the dry contact device, dividing the signal flow path and ensuring that the signal can be correctly transmitted between the dry contact device and the protection circuit.

[0038] Please refer to Figure 2 , specifically, the signal isolation circuit comprises a first resistor R3, a second resistor R6 and an operational amplifier; the second terminal port 2 of the terminal J1 is connected to the non-inverting input terminal of the operational amplifier through the first resistor R3; one end of the second resistor R6 is connected to the inverting input terminal of the operational amplifier, and the other end of the second resistor R6 is connected to the output terminal of the operational amplifier; the pin 4 of the operational amplifier is connected to the ground, and the pin UIA of the operational amplifier is connected to the power supply end of the working voltage, which provides the positive power voltage required by the internal circuit of the operational amplifier.

[0039] In this embodiment, the operational amplifier has the characteristics of high input impedance and low output impedance, which makes it effective in isolating the front and rear circuits.

[0040] Pin 3 of the operational amplifier receives the signal from the second terminal 2 of the terminal J1 through the first resistor R3. Pin 2 of the operational amplifier is connected to pin 1 of the operational amplifier through the second resistor R6, thus forming a voltage follower. As a voltage follower, the operational amplifier can buffer the input signal and provide sufficient current driving capability to ensure that the signal can be effectively processed in the subsequent circuit, avoiding signal distortion due to excessive load during transmission.

[0041] The first resistor R3 functions as a current limiter and a voltage divider, limiting the current flowing from the terminal J1 to the non-inverting input of the operational amplifier, preventing excessive current from damaging the operational amplifier. At the same time, it can also divide the input signal and adjust the amplitude of the input signal. The second resistor R6 forms a feedback loop with the operational amplifier, helping to stabilize the output of the operational amplifier, so that it can accurately follow the voltage changes of the non-inverting input.

[0042] The signal isolation circuit can achieve electrical isolation, preventing the influence of the previous stage circuit (such as possible interference sources or high voltage circuits) on the subsequent stage circuit. Due to the high input impedance of the operational amplifier, its load effect on the previous stage circuit is small, which will not affect the normal operation of the previous stage circuit. At the same time, the low output impedance of the operational amplifier can effectively drive the subsequent circuit, ensuring that the signal can be stably transmitted to the subsequent circuit module. In addition, the circuit composed of the operational amplifier and related resistors can effectively suppress external interference, ensuring the integrity and accuracy of the input signal.

[0043] Please refer to Figure 2 , specifically, the level conversion circuit includes a third resistor R5, a fourth resistor R2 and a transistor V1; the output of the operational amplifier is connected to the base of the transistor V1 through the third resistor R5; the emitter of the transistor V1 is grounded; the collector of the transistor V1 is connected to the power supply end of the working voltage through the fourth resistor R2.

[0044] In this embodiment, the transistor V1 is an NPN transistor V1. When the operational amplifier outputs a high level, the transistor V1 is turned on, and the collector voltage of the transistor V1 approaches the ground level (emitter voltage), realizing the conversion from high level to low level. The third resistor R5 functions as a current limiter, limiting the current flowing from the output of the operational amplifier to the base of the transistor V1, preventing excessive current from damaging the transistor V1. The fourth resistor R2 functions as a voltage divider and a current limiter, limiting the current flowing from the power supply VDD to the collector of the transistor V1, while cooperating with the on and off states of the transistor V1 to realize voltage division during the level conversion process, ensuring that the output level meets the requirements.

[0045] In the implementation, when the output of the operational amplifier is low, the transistor V1 is cut off, and the collector voltage is close to the power supply voltage VDD, realizing the conversion from low to high. The level conversion circuit can convert the level output by the operational amplifier into a level suitable for subsequent circuit processing. For example, when the circuit in which the operational amplifier is located works in a voltage range, and the subsequent circuit needs to work in a different voltage range (convert the signal isolation circuit output level into a voltage value that can be borne by the IO interface of the MCU), through the level conversion circuit, the signal level can be converted between different voltage domains, and the relatively wide input voltage can be converted into a voltage value that can be accepted by the MCU, ensuring correct transmission and processing of the signal.

[0046] Referring to Figure 2 , specifically, the voltage clamping circuit includes a fifth resistor R4, a first unidirectional diode D1, and a second unidirectional diode D3; one end of the fifth resistor is connected to the collector of the transistor V1, and the other end of the fifth resistor is connected to the anode of the first unidirectional diode D1, the cathode of the second unidirectional diode D3, and the signal input end of the MCU, respectively; the cathode of the first unidirectional diode D1 is connected to the working voltage under power supply end; and the anode of the second unidirectional diode D3 is grounded.

[0047] In the embodiment, the fifth resistor R4 functions as a current limiter, limiting the size of the current flowing from the collector of the transistor V1 to the signal input end of the MCU, preventing damage to related elements caused by excessive current when the diode is turned on for voltage clamping. At the same time, the fifth resistor R4 also helps to appropriately divide and limit the current of the signal in the normal working state, ensuring that the signal is transmitted within a suitable range. The cathode of the first unidirectional diode D1 is connected to the working voltage VDD power supply end, and the anode is connected to one end of the fifth resistor R4. When the voltage at the other end of the fifth resistor R4 is higher than VDD, the first unidirectional diode D1 is turned on, clamping the voltage around the working voltage VDD, preventing damage to the signal input end of the MCU caused by excessively high voltage. The anode of the second unidirectional diode D3 is grounded, and the cathode is connected to one end of the fifth resistor R4. When the voltage at the other end of the fifth resistor R4 is lower than 0V (i.e., a negative voltage occurs), the second unidirectional diode D3 is turned on, clamping the voltage around 0V, preventing damage to the signal input end of the MCU caused by negative voltage.

[0048] The voltage clamping circuit protects the signal input end of the MCU. In the circuit, excessively high or low voltage can cause damage to the MCU or abnormal working. Through the voltage clamping effect of the first unidirectional diode D1 and the second unidirectional diode D3, combined with the current limiting function of the fifth resistor R4, it can be ensured that the voltage input from the collector of the transistor V1 to the signal input end of the MCU is limited within a safe range, ensuring the integrity of the signal input to the MCU.

[0049] The dry contact input signal protection circuit of the embodiment realizes protection of the direct connection state of the dry contact device, and avoids the problem of damage of the dry contact device caused by a surge when the dry contact device is directly connected to an outdoor or high-voltage power supply device without isolation.

[0050] In another embodiment, the surge protection circuit can also achieve surge protection by connecting a resistor and a voltage stabilizing diode. The resistor is used to limit the current, and the voltage stabilizing diode can stabilize the voltage within a safe range. For example, when a surge voltage occurs, the voltage stabilizing diode will first conduct to bypass the excess voltage.

[0051] Referring to Figure 3 The embodiment of the present application provides a dry contact device comprising the dry contact input signal protection circuit according to the foregoing.

[0052] The technical effect of the embodiment is the same as that of the dry contact input signal protection circuit.

[0053] Referring to Figure 4 The embodiment of the present application provides a distributed photovoltaic system comprising the dry contact device according to the foregoing.

[0054] The technical effect of the embodiment is the same as that of the dry contact input signal protection circuit. In summary, the foregoing description of the specific exemplary embodiments of the present application is for the purpose of illustration and example, and these descriptions are not intended to limit the present application to the precise form disclosed, and it is obvious that many changes and modifications can be made according to the above teachings, although embodiments of the present application have been shown and described, the specific embodiments are merely an explanation of the present application, and are not a limitation of the present application, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner, the purpose of selecting and describing the exemplary embodiments is to explain the specific principles of the present application and its practical application, so that those skilled in the art can make modifications, replacements, variations and various different selections and changes to the embodiments without creative contribution after reading the present specification, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A dry contact input signal protection circuit applied in a dry contact device, characterized in that, The power current limiting and surge protection circuit, the surge protection circuit, the signal isolation circuit, the level conversion circuit, the voltage clamping circuit and the MCU are included. The input end of the power current limiting and surge protection circuit is connected with the power supply end of voltage output, and the output end of the power current limiting and surge protection circuit is connected with the signal input end of the dry contact device; the input end of the surge protection circuit is connected with the signal output end of the dry contact device; and the output end of the surge protection circuit is connected with the signal isolation circuit, the level conversion circuit, the voltage clamping circuit and the MCU in sequence.

2. A dry contact input signal protection circuit according to claim 1, wherein, The power current limiting and surge protection circuit includes the first secondary discharge tube and the current limiting resistor; one end of the current limiting resistor is connected with the power supply end, and the other end of the current limiting resistor is connected with the signal input end of the dry contact device; one end of the first secondary discharge tube is grounded, and the other end of the first secondary discharge tube is connected with the signal input end of the dry contact device.

3. A dry contact input signal protection circuit according to claim 2, wherein, The surge protection circuit includes the second secondary discharge tube and the transient suppression diode in parallel; one end of the parallel connection of the second secondary discharge tube and the transient suppression diode is connected with the signal output end of the dry contact device, and the other end of the parallel connection of the second secondary discharge tube and the transient suppression diode is grounded.

4. A dry contact input signal protection circuit according to claim 3, wherein The wiring terminal is further included; the other end of the current limiting resistor and the other end of the first secondary discharge tube are connected with the first wiring port of the wiring terminal, the first wiring port of the wiring terminal is connected with the signal input end of the dry contact device; one end of the parallel connection of the second secondary discharge tube and the transient suppression diode is connected with the second wiring port of the wiring terminal, and the second wiring port of the wiring terminal is connected with the signal output end of the dry contact device.

5. A dry contact input signal protection circuit according to claim 4, wherein, The signal isolation circuit includes the first resistor, the second resistor and the operational amplifier; the second wiring port of the wiring terminal is connected with the non-inverting input end of the operational amplifier through the first resistor; one end of the second resistor is connected with the inverting input end of the operational amplifier, and the other end of the second resistor is connected with the output end of the operational amplifier; and the operational amplifier is further connected with the ground and the power supply end of working voltage respectively.

6. A dry contact input signal protection circuit according to claim 5, wherein, The level conversion circuit includes the third resistor, the fourth resistor and the transistor; the output end of the operational amplifier is connected with the base of the transistor through the third resistor; the emitter of the transistor is grounded; and the collector of the transistor is connected with the power supply end of working voltage through the fourth resistor.

7. A dry contact input signal protection circuit according to claim 6, wherein The voltage clamping circuit includes the fifth resistor, the first unidirectional diode and the second unidirectional diode; one end of the fifth resistor is connected with the collector of the transistor, and the other end of the fifth resistor is connected with the signal input end of the MCU, the anode of the first unidirectional diode and the cathode of the second unidirectional diode respectively; the cathode of the first unidirectional diode is connected with the power supply end of working voltage; and the anode of the second unidirectional diode is grounded.

8. A dry contact device, characterized by The dry contact input signal protection circuit includes any one of claims 1-7.

9. A distributed photovoltaic system, characterized by, The dry contact device includes claim 8.

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