Leakage protection auxiliary circuit, photovoltaic inverter and photovoltaic inversion system

Abstract

The utility model relates to the technical field of inverters, in particular to an electric leakage protection auxiliary circuit, a photovoltaic inverter and a photovoltaic inversion system. The circuit comprises a main control chip, a relay module and an over-current protection module, the main control chip is connected with the control end of the relay module, and the relay module and the over-current protection module are connected in series and then used for being connected between a zero line of the input end of an external leakage protection switch and a ground wire of an external load. The overcurrent protection module is used for limiting the current between the zero line of the input end of the external leakage protection switch and the ground wire of the external load. The current flowing through the relay module can be limited, the relay module is protected, the relay module is prevented from being damaged, and potential safety hazards are reduced.

Description

TECHNICAL FIELD

[0001] The utility model relates to inverter technical field especially is a kind of leakage protection auxiliary circuit, photovoltaic inverter and photovoltaic inverter system. BACKGROUND

[0002] In daily resident electricity, electrical equipment can appear ground short-circuit fault, and safety accident occurs due to equipment leakage. Therefore, the power grid of residence generally adds a leakage protection switch, and the zero line of power grid is connected with ground, when electrical equipment appears leakage to ground, leakage loop is formed with ground, and the leakage protection switch detects that leakage current exceeds safety value, then the leakage protection switch acts and disconnects mains.

[0003] Some users will install photovoltaic inverter, and most of the time is disconnected mains input, and photovoltaic inverter is powered by load, and photovoltaic inverter is off-grid with load. In this case, when load leakage to ground occurs, leakage protection switch cannot detect leakage current due to no ground loop connected with ground, and cannot play a protective role. Therefore, ground loop is set in some photovoltaic inverters.

[0004] In some related technologies, photovoltaic inverter is connected with ground by increasing a relay to control the input end zero line of leakage protection switch to connect ground inside photovoltaic inverter, to achieve the purpose of zero line grounding. However, in this mode, when leakage protection switch fails, large current to ground can flow through relay, causing relay to be damaged by overcurrent, and there is a security risk. UTILITY MODEL CONTENT

[0005] The technical problem to be solved by the embodiment of the utility model is to provide a leakage protection auxiliary circuit, photovoltaic inverter and photovoltaic inverter system, to solve the problem of security risk of photovoltaic inverter in prior art when external leakage protection switch fails.

[0006] The utility model discloses a leakage protection auxiliary circuit, including main control chip, relay module and overcurrent protection module, the control end of main control chip is connected with relay module, the relay module is connected in series with overcurrent protection module and is used for connecting between the input end zero line of external leakage protection switch and the ground wire of external load, and the overcurrent protection module is used for limiting the current between the input end zero line of external leakage protection switch and the ground wire of external load.

[0007] Optionally, the leakage protection auxiliary circuit further includes voltage attenuation module, the voltage attenuation module is used for detecting the voltage value of both ends after the relay module is connected in series with the overcurrent protection module, and the voltage value is transmitted to the main control chip after attenuation processing, and the main control chip is used for comparing voltage value with preset value, and the output of photovoltaic inverter is controlled according to the comparison result.

[0008] Optionally, the voltage attenuation module comprises an operational amplifier, a first resistor, a second resistor, a third resistor and a fourth resistor, the first resistor is connected in series between the input end zero line of the external leakage protection switch and the non-inverting input end of the operational amplifier, the second resistor is connected in series between the ground line of the external load and the inverting input end of the operational amplifier, one end of the third resistor is connected to the non-inverting input end of the operational amplifier, the other end of the third resistor is grounded, one end of the fourth resistor is connected to the inverting input end of the operational amplifier, the other end of the fourth resistor is connected to the output end of the operational amplifier, and the output end of the operational amplifier is also connected to the master control chip.

[0009] Optionally, the overcurrent protection module comprises a self-resetting fuse, one end of the self-resetting fuse is connected to the relay module, and the other end of the self-resetting fuse is connected to the ground line of the external load.

[0010] Optionally, the relay module comprises a relay, a control end of the relay is connected to the master control chip, a first end of the relay is connected to the input end zero line of the external leakage protection switch, and a second end of the relay is connected to one end of the self-resetting fuse.

[0011] Optionally, the overcurrent protection module comprises a plurality of self-resetting fuses, the plurality of self-resetting fuses are connected in series, one end of the plurality of self-resetting fuses connected in series is connected to the relay module, and the other end of the plurality of self-resetting fuses connected in series is connected to the ground line of the external load, or the plurality of self-resetting fuses are connected in parallel, one parallel node of the plurality of self-resetting fuses connected in parallel is connected to the relay module, and the other parallel node of the plurality of self-resetting fuses connected in parallel is connected to the ground line of the external load.

[0012] Optionally, the overcurrent protection module comprises a thermistor, one end of the thermistor is connected to the relay module, and the other end of the thermistor is connected to the ground line of the external load.

[0013] Optionally, the overcurrent protection module comprises a plurality of thermistors, the plurality of thermistors are connected in series, one end of the plurality of thermistors connected in series is connected to the relay module, and the other end of the plurality of thermistors connected in series is connected to the ground line of the external load, or the plurality of thermistors are connected in parallel, one parallel node of the plurality of thermistors connected in parallel is connected to the relay module, and the other parallel node of the plurality of thermistors connected in parallel is connected to the ground line of the external load.

[0014] The utility model discloses still disclose a kind of photovoltaic inverter, including the leakage protection auxiliary circuit as described above.

[0015] The utility model discloses still disclose a kind of photovoltaic inverter system, including leakage protection switch and the photovoltaic inverter as described above, the leakage protection switch is arranged between the photovoltaic inverter and external load, and the input end zero line of the leakage protection switch is connected the relay module.

[0016] Compared with the prior art, the beneficial effects of the leakage protection auxiliary circuit, the photovoltaic inverter and the photovoltaic inverter system provided by the embodiment of the utility model lie in that: the leakage protection auxiliary circuit is provided with the master control chip, the relay module and the overcurrent protection module, the overcurrent protection module can limit the current between the input end zero line of the external leakage protection switch and the ground line of the external load, the overcurrent protection module and the relay module are connected between the input end zero line of the external leakage protection switch and the ground line of the external load in series, when the external leakage protection switch is invalid, the overcurrent protection module can limit the current flowing through the relay module, the relay module is protected, the relay module is prevented from being damaged, and the safety hidden danger is reduced. BRIEF DESCRIPTION OF DRAWINGS

[0017] The technical scheme of the utility model will be further explained in detail below in combination with the drawings and the embodiments, and the drawings are as follows:

[0018] Figure 1 is the structural block diagram of the leakage protection auxiliary circuit provided by the embodiment of the utility model;

[0019] Figure 2 is the circuit schematic diagram of the photovoltaic inverter system provided by the embodiment of the utility model.

[0020] The various reference signs in the drawings are as follows:

[0021] 100, leakage protection auxiliary circuit;

[0022] 110, master control chip; 120, relay module; 130, overcurrent protection module; 140, voltage attenuation module;

[0023] U1A, operational amplifier; R1, first resistor; R2, second resistor; R3, third resistor; R4, fourth resistor; PPTC1, self-recovery fuse; K1, relay;

[0024] 200, photovoltaic inverter;

[0025] 300, photovoltaic inverter system; 310, leakage protection switch. DETAILED DESCRIPTION

[0026] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict. The preferred embodiments of the utility model will be described in detail in combination with the drawings.

[0027] The embodiment of the utility model provides a kind of leakage protection auxiliary circuit 100, it is applied to photovoltaic inverter 200, in photovoltaic inverter 200 off-grid condition, can cooperate with external leakage protection switch 310 to realize the double protection of leakage.

[0028] As Figure 1 It is shown that the leakage protection auxiliary circuit 100 includes a master control chip 110, a relay module 120 and an overcurrent protection module 130, the master control chip 110 is connected with the control end of the relay module 120, the relay module 120 and the overcurrent protection module 130 are connected in series and are used for connecting between the input end zero line of the external leakage protection switch 310 and the ground line of the external load, and the overcurrent protection module 130 is used for limiting the current between the input end zero line of the external leakage protection switch 310 and the ground line of the external load.

[0029] The leakage protection auxiliary circuit 100 of the embodiment of the present application can limit the current between the input end zero line of the external leakage protection switch 310 and the ground line of the external load by setting the master control chip 110, the relay module 120 and the overcurrent protection module 130, the overcurrent protection module 130 is connected in series with the relay module 120 and is connected between the input end zero line of the external leakage protection switch 310 and the ground line of the external load, when the external leakage protection switch 310 is invalid, the overcurrent protection module 130 can limit the current flowing through the relay module 120, and the relay module 120 is protected, so that the relay module 120 is prevented from being damaged and the security risk is reduced.

[0030] The master control chip 110 can control the relay module 120 by using the existing chip, controls the relay module 120 to be turned on or turned off, controls the relay module 120 to be turned on when the photovoltaic inverter 200 is in off-grid operation, so as to connect the input end zero line of the external leakage protection switch 310 to the ground line of the external load and form a grounding loop.

[0031] In the optional embodiment of the present application, the leakage protection auxiliary circuit 100 further includes a voltage attenuation module 140, the voltage attenuation module 140 is used for detecting the voltage value between the relay module 120 and the overcurrent protection module 130 connected in series, and transmitting the voltage value after attenuation processing to the master control chip 110, and the master control chip 110 is used for comparing the voltage value with a preset value and controlling the output of the photovoltaic inverter 200 according to the comparison result.

[0032] By setting the voltage attenuation module 140, the voltage value between the relay module 120 and the overcurrent protection module 130 connected in series can be acquired, that is, as Figure 1 and Figure 2The voltage of the a point and the b point in the figure can be used by the master control chip 110 to determine whether the relay module 120 or the overcurrent protection module 130 is faulty, and then stop the photovoltaic inverter 200 from outputting in the case of failure, reduce the security risks, and ensure personal safety. The master control chip 110 compares the voltage value with a preset value, and controls the photovoltaic inverter 200 to stop outputting according to the comparison result, which can be realized by an existing chip. The output of the photovoltaic inverter 200 is specifically the control of the switching device in the photovoltaic inverter 200, and then the output of the photovoltaic inverter 200, which is a conventional technology and will not be described here.

[0033] Specifically, when the relay module 120 fails to reliably attract and conduct or the overcurrent protection module 130 fails, the voltage decay module 140 can detect the voltage value across the relay module 120 and the overcurrent protection module 130 in series, and transmit the voltage value to the master control chip 110 after decay processing. The master control chip 110 determines that the leakage protection auxiliary circuit 100 is faulty according to the voltage value, which can help the staff to monitor the leakage protection auxiliary circuit 100 in real time, find and troubleshoot the fault in time, and reduce the security risks.

[0034] Reference Figure 1 and Figure 2 In the optional embodiment of the present application, the voltage decay module 140 includes an operational amplifier U1A, a first resistor R1, a second resistor R2, a third resistor R3, and a fourth resistor R4. The first resistor R1 is connected in series between the input end zero line of the external leakage protection switch 310 and the non-inverting input end of the operational amplifier U1A. The second resistor R2 is connected in series between the ground line of the external load and the inverting input end of the operational amplifier U1A. One end of the third resistor R3 is connected to the non-inverting input end of the operational amplifier U1A, and the other end of the third resistor R3 is grounded. One end of the fourth resistor R4 is connected to the inverting input end of the operational amplifier U1A, and the other end of the fourth resistor R4 is connected to the output end of the operational amplifier U1A. The output end of the operational amplifier U1A is also connected to the master control chip 110.

[0035] The first resistor R1 and the second resistor R2 are high-voltage isolation sampling resistors, which sample the voltage through the relay module 120 and the overcurrent protection module 130, that is, the voltage of the a point and the b point in the figure, so as to realize the electrical isolation between the high-voltage circuit and the low-voltage circuit, that is, the electrical isolation between the external leakage protection switch side and the master control chip 110. Figure 2 The operational amplifier U1A, the first resistor R1, the second resistor R2, the third resistor R3, and the fourth resistor R4 form a differential amplification circuit, which can output the voltage value obtained by sampling to the master control chip 110 after decay, thereby reducing the influence of the high-voltage side on the master control chip 110.

[0036] The first resistor R1 has the same resistance value as the second resistor R2, the third resistor R3 and the fourth resistor R4 have the same resistance value, and the attenuation multiple is the ratio of the fourth resistor R4 to the second resistor R2. The worker can set the resistance values of the fourth resistor R4 and the second resistor R2 to achieve the required attenuation multiple, output a suitable voltage, and transmit the voltage to the main control chip 110.

[0037] The voltage detection and attenuation processing are realized by setting the operational amplifier U1A, the first resistor R1, the second resistor R2, the third resistor R3, and the fourth resistor R4. The circuit structure is simple, and the cost is low. Of course, in other embodiments, the voltage attenuation module 140 can also be realized by using other circuit structures. For example, the first resistor R1, the second resistor R2, the third resistor R3, and the fourth resistor R4 in the above embodiment can each be composed of a plurality of resistors in series, and the resistance values of the plurality of resistors in series are the same as the resistance values of the corresponding first resistor R1, the second resistor R2, the third resistor R3, and the fourth resistor R4. The plurality of resistors in series can also cooperate with the operational amplifier U1A to realize voltage sampling and voltage signal attenuation.

[0038] Reference Figure 1 and Figure 2 In the embodiment of the present application, the overcurrent protection module 130 includes a self-resetting fuse PPTC1. One end of the self-resetting fuse PPTC1 is connected with the relay module 120, and the other end is connected with the ground wire of the external load.

[0039] The self-resetting fuse PPTC1 is an overcurrent electronic protection element. It is made of a high-molecular organic polymer, which is mixed with conductive particle materials under the conditions of high pressure, high temperature, and vulcanization reaction, and is processed by a special process. The traditional overcurrent protection of the fuse can only protect once, and needs to be replaced after being burned out. The self-resetting fuse PPTC1 has the functions of overcurrent and overheating protection and automatic recovery, does not need to be frequently replaced by manual work, reduces maintenance cost and time, and can respond to overload or short circuit conditions within milliseconds during the overcurrent protection process, rapidly increases the resistance to limit the current, and effectively protects the circuit from damage.

[0040] By setting the self-resetting fuse PPTC1, when a large current flows through the self-resetting fuse PPTC1 and exceeds the action current of the self-resetting fuse PPTC1 in the case where the external leakage protection switch 310 fails, the self-resetting fuse PPTC1 is in a high-resistance state, which plays a role in breaking and limiting the current to protect the relay module 120.

[0041] In other embodiments, the overcurrent protection module 130 can also include a plurality of self-resetting fuses PPTC1, the plurality of self-resetting fuses PPTC1 are connected in series, one end of the plurality of self-resetting fuses PPTC1 connected in series is connected to the relay module 120, and the other end is connected to the ground of the external load, or the plurality of self-resetting fuses PPTC1 are connected in parallel, one parallel node of the plurality of self-resetting fuses PPTC1 connected in parallel is connected to the relay module 120, and the other parallel node is connected to the ground of the external load. The plurality of self-resetting fuses PPTC1 connected in parallel or in series can also achieve current limiting, protect the relay module 120, and the number of self-resetting fuses PPTC1 can be set according to requirements to adapt to different currents or voltages.

[0042] The number of self-resetting fuses PPTC1 can be two, three or more, and the user can select and set according to different currents or voltages. In this embodiment, one self-resetting fuse PPTC1 is used, and the circuit structure is simple.

[0043] In another embodiment, the overcurrent protection module 130 can also use a thermistor, one end of the thermistor is connected to the relay module 120, and the other end is connected to the ground of the external load. The thermistor is a resistor whose resistance value changes with temperature. In this embodiment, a PTC (Positive Temperature Coefficient) thermistor is used, and the resistance of the PTC thermistor increases with temperature. When the external leakage protection switch 310 fails and a large current flows through the PTC thermistor, the temperature of the PTC thermistor rises, and the resistance of the PTC thermistor increases with the rise in temperature, thereby limiting the current and protecting the relay module 120.

[0044] In yet another embodiment, the overcurrent protection module 130 can also include a plurality of thermistors, the plurality of thermistors are connected in series, one end of the plurality of thermistors connected in series is connected to the relay module 120, and the other end is connected to the ground of the external load, or the plurality of thermistors are connected in parallel, one parallel node of the plurality of thermistors connected in parallel is connected to the relay module 120, and the other parallel node is connected to the ground of the external load. The thermistors in this embodiment also use PTC thermistors. The plurality of PTC thermistors connected in parallel or in series can also achieve current limiting, protect the relay module 120, and the number of thermistors can be set according to requirements to adapt to different currents or voltages.

[0045] In this embodiment, reference is made to Figure 1 and Figure 2The relay module 120 includes a relay K1, a control end of the relay K1 is connected with the master control chip 110, a first end of the relay K1 is connected with an input end zero line of the external leakage protection switch 310, and a second end is connected with one end of the self-recovery fuse PPTC1.

[0046] The relay K1 serves as a switch, when the self-recovery fuse PPTC1 is in a low resistance state, the relay K1 can turn on a path between the input end zero line of the external leakage protection switch 310 and a ground line of an external load, so as to form a ground loop.

[0047] In other embodiments, the relay module 120 can also include a plurality of relays K1, the plurality of relays K1 are connected in series, one end connected in series is connected with the input end zero line of the external leakage protection switch 310, the other end is connected with one end of the self-recovery fuse PPTC1, and control ends of the plurality of relays K1 are connected with the master control chip 110, and the master control chip 110 can control the plurality of relays K1 to be turned on or turned off. In this embodiment, one relay K1 is used, and the circuit structure is simpler.

[0048] The application also provides a photovoltaic inverter 200, referring to Figure 2 The photovoltaic inverter 200 includes the leakage protection auxiliary circuit 100 described above. When the photovoltaic inverter 200 is in an off-grid working state, leakage protection can be realized in cooperation with the external leakage protection switch 310.

[0049] The leakage protection auxiliary circuit 100 in the photovoltaic inverter 200 of the application is connected between the input end zero line of the external leakage protection switch 310 and the ground line of the external load through the master control chip 110, the relay module 120 and the overcurrent protection module 130. The overcurrent protection module 130 can limit the current between the input end zero line of the external leakage protection switch 310 and the ground line of the external load. When the external leakage protection switch 310 fails, the overcurrent protection module 130 can limit the current flowing through the relay module 120, so as to protect the relay module 120, avoid damage to the relay module 120, and reduce the security risk.

[0050] The specific circuit structure of the leakage protection auxiliary circuit 100 in the photovoltaic relay K1 is the same as that of the leakage protection auxiliary circuit 100 described above, and the technical effects are the same, which will not be repeated here.

[0051] The application also provides a photovoltaic inverter system 300, referring to Figure 2The photovoltaic inverter system 300 comprises the leakage protection switch 310 and the photovoltaic inverter 200 as described above, the leakage protection switch 310 is arranged between the photovoltaic inverter 200 and the external load, and the input end of the leakage protection switch 310 is connected with the relay module 120.

[0052] The leakage protection switch 310 is also called leakage circuit breaker, which is mainly used for protecting the human body from electric shock when the device has a leakage fault, and has the functions of overload and short circuit protection, and can be used for protecting the overload and short circuit of the line or motor, and can also be used as the infrequent switching start of the line in the normal condition. The leakage protection switch 310 in the embodiment of the present application can be realized by using the conventional technology, which is not the improvement point of the present application, and will not be described here.

[0053] When the photovoltaic inverter 200 is in the off-grid working state, the photovoltaic inverter 200 can realize double leakage protection in cooperation with the leakage protection switch 310.

[0054] The specific circuit structure and beneficial effects of the photovoltaic inverter 200 in the photovoltaic inverter system 300 are the same as those of the specific structure and technical effects of the photovoltaic inverter 200 described above, and will not be described here.

[0055] It should be understood that the above embodiments are only used to illustrate the technical solutions of the present application, but not to limit them, and the technical solutions recorded in the above embodiments can be modified by those skilled in the art, or some technical features can be replaced by the equivalent; all these modifications and replacements should belong to the protection scope of the claims of the present application.

Claims

1. A leakage protection auxiliary circuit applied in a photovoltaic inverter, characterized in that, The leakage protection auxiliary circuit comprises a master control chip, a relay module and an overcurrent protection module, the master control chip is connected with a control end of the relay module, the relay module and the overcurrent protection module are connected in series and used for being connected between an input end zero line of an external leakage protection switch and a ground line of an external load, and the overcurrent protection module is used for limiting the current between the input end zero line of the external leakage protection switch and the ground line of the external load.

2. The ground fault protection auxiliary circuit of claim 1, wherein, The leakage protection auxiliary circuit further comprises a voltage attenuation module, the voltage attenuation module is used for detecting a voltage value between the relay module and the overcurrent protection module connected in series, and transmitting the voltage value after attenuation processing to the master control chip, and the master control chip is used for comparing the voltage value with a preset value and controlling the output of the photovoltaic inverter according to a comparison result.

3. The ground fault protection auxiliary circuit of claim 2, wherein, The voltage attenuation module comprises an operational amplifier, a first resistor, a second resistor, a third resistor and a fourth resistor, the first resistor is connected in series between the input end zero line of the external leakage protection switch and a positive phase input end of the operational amplifier, the second resistor is connected in series between the ground line of the external load and an inverting input end of the operational amplifier, one end of the third resistor is connected with the positive phase input end of the operational amplifier, the other end of the third resistor is grounded, one end of the fourth resistor is connected with the inverting input end of the operational amplifier, and the other end of the fourth resistor is connected with an output end of the operational amplifier, and the output end of the operational amplifier is further connected with the master control chip.

4. The ground-fault circuit-interrupter auxiliary circuit of any one of claims 1-3, wherein, The overcurrent protection module comprises a self-resetting fuse, one end of the self-resetting fuse is connected with the relay module, and the other end of the self-resetting fuse is connected with the ground line of the external load.

5. The ground fault protection auxiliary circuit of claim 4, wherein, The relay module comprises a relay, a control end of the relay is connected with the master control chip, a first end of the relay is connected with the input end zero line of the external leakage protection switch, and a second end of the relay is connected with one end of the self-resetting fuse.

6. The ground fault protection auxiliary circuit according to any one of claims 1-3, characterized in that, The overcurrent protection module comprises a plurality of self-resetting fuses, the plurality of self-resetting fuses are connected in series, one end of the plurality of self-resetting fuses connected in series is connected with the relay module, and the other end of the plurality of self-resetting fuses connected in series is connected with the ground line of the external load, or the plurality of self-resetting fuses are connected in parallel, one parallel node of the plurality of self-resetting fuses connected in parallel is connected with the relay module, and the other parallel node of the plurality of self-resetting fuses connected in parallel is connected with the ground line of the external load.

7. The ground fault protection auxiliary circuit according to any one of claims 1-3, characterized in that, The overcurrent protection module comprises a thermistor, one end of the thermistor is connected with the relay module, and the other end of the thermistor is connected with the ground line of the external load.

8. The ground fault protection auxiliary circuit according to any one of claims 1-3, characterized in that, The overcurrent protection module comprises a plurality of thermistors, the plurality of thermistors are connected in series, one end of the plurality of thermistors connected in series is connected with the relay module, and the other end of the plurality of thermistors connected in series is connected with the ground line of the external load, or the plurality of thermistors are connected in parallel, one parallel node of the plurality of thermistors connected in parallel is connected with the relay module, and the other parallel node of the plurality of thermistors connected in parallel is connected with the ground line of the external load.

9. A photovoltaic inverter, characterized by The leakage protection auxiliary circuit comprises a leakage protection auxiliary circuit according to any one of claims 1-8.

10. A photovoltaic inverter system, characterized by, The photovoltaic inverter as claimed in claim 8, wherein a leakage protection switch is provided between the photovoltaic inverter and an external load, and an input line of the leakage protection switch is connected to the relay module.

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