Ground wire reliability detection circuit and alternating current charging pile

Abstract

The utility model discloses a ground wire reliability detection circuit and an alternating current charging pile, relates to the technical field of circuits, and discloses the ground wire reliability detection circuit which comprises a voltage conversion unit and a detection unit. The voltage conversion unit is arranged between three phase lines and a ground line and is used for converting three-phase electricity output by the three phase lines into non-three-phase electricity and outputting the non-three-phase electricity to the ground line; and the detection unit is used for measuring the voltage difference between the ground wire and the zero wire, and outputting prompt information for representing that the ground wire is unreliable under the condition that the voltage difference is greater than a first value. The ground wire reliability detection circuit is designed by utilizing an existing three-phase five-wire system, the circuit structure is simple, the condition that the ground wire is unreliable can be conveniently identified, and the grounding safety of equipment such as a charging pile is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of circuit, in particular to a ground wire reliability detection circuit and an alternating current charging pile. BACKGROUND

[0002] With the rapid development of new energy automobile industry, the safety and reliability of electric vehicle charging pile as a core supporting facility are concerned. In the electrical system of the charging pile, grounding protection is a key technical link to protect the safety of equipment and users.

[0003] According to the national standard, the metal shell equipment needs to have reliable grounding. The traditional charging pile usually adopts an independent ground wire connection mode, that is, the metal conductor is used to directly connect the conductive parts such as the shell of the charging pile and the charging gun head with the ground, so as to eliminate the potential difference generated when the equipment leaks and avoid the risk of electric shock of users.

[0004] However, using the above independent ground wire connection mode, the disconnection of the ground wire of the charging pile often does not affect the work of the charging pile, and the abnormal conditions such as disconnection of the ground wire are not easy to be identified, thereby there is a great safety hazard, resulting in poor safety of the charging pile.

[0005] The above content is only used to assist in understanding the technical solutions of the present application, and does not represent the acknowledgement of the above content as prior art. UTILITY MODEL CONTENT

[0006] The main purpose of the present application is to provide a ground wire reliability detection circuit and an alternating current charging pile, which aims to solve the technical problem that the abnormal conditions such as disconnection of the ground wire are not easy to be identified in the related art, thereby there is a great safety hazard, resulting in poor safety of the charging pile.

[0007] In order to achieve the above purpose, the present application provides a ground wire reliability detection circuit, which comprises a voltage conversion unit and a detection unit.

[0008] The voltage conversion unit is arranged between three phase lines and a ground wire, and is used to convert three-phase power output by the three phase lines into non-three-phase power and then output to the ground wire.

[0009] The detection unit is used to measure the voltage difference between the ground wire and a zero line, and output prompt information for indicating that the ground wire is unreliable when the voltage difference is greater than a first value.

[0010] In an embodiment, a first capacitor is connected between the zero line and the ground wire, the three phase lines include a first phase line, a second phase line and a third phase line, and the voltage conversion unit includes a second capacitor, a third capacitor and a fourth capacitor.

[0011] The second capacitor is connected between the first phase line and the ground line, the third capacitor is connected between the second phase line and the ground line, and the fourth capacitor is connected between the third phase line and the ground line.

[0012] The capacitance values of the second capacitor, the third capacitor and the fourth capacitor are not all the same.

[0013] In an embodiment, the first capacitor, the second capacitor, the third capacitor and the fourth capacitor are Y capacitors.

[0014] In an embodiment, the detection unit comprises a signal conversion unit, a comparison unit and a processing unit.

[0015] The signal conversion unit is configured to convert the voltage difference into a target voltage within a voltage range supported by the comparison unit, and output the target voltage to the comparison unit.

[0016] The comparison unit is configured to compare the target voltage with a preset reference voltage, and output a target signal to the processing unit if the target voltage is greater than the reference voltage.

[0017] The processing unit is configured to output the prompt information after receiving the target signal.

[0018] In an embodiment, the signal conversion unit comprises a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor and a first operational amplifier.

[0019] The inverting input terminal of the first operational amplifier is connected to the neutral line through the first resistor, the non-inverting input terminal of the first operational amplifier is connected to the ground line through the second resistor, the inverting input terminal of the first operational amplifier is further connected to the output terminal of the first operational amplifier through the third resistor, the non-inverting input terminal of the first operational amplifier is further connected to a high level through the fourth resistor and grounded through the fifth resistor, and the output terminal of the first operational amplifier serves as the output terminal of the signal conversion unit.

[0020] In an embodiment, the detection unit further comprises an isolation unit, and the inverting input terminal of the first operational amplifier is connected to the neutral line through the first resistor and the isolation unit.

[0021] In an embodiment, the isolation unit comprises a fifth capacitor.

[0022] In an embodiment, the comparison unit comprises a sixth resistor, a seventh resistor, an eighth resistor, a ninth resistor and a second operational amplifier.

[0023] The same direction input end of the second operational amplifier is used for receiving the target voltage, the opposite direction input end of the second operational amplifier is connected to high level through the sixth resistance and grounded through the seventh resistance, used for providing the reference voltage, the same direction input end of the second operational amplifier is also connected to the output end of the second operational amplifier through the eighth resistance, the output end of the second operational amplifier is connected to high level through the ninth resistance, and the output end of the second operational amplifier is used as the output end of the comparison unit.

[0024] In an embodiment, the processing unit is a micro control unit, and the target signal is a square wave signal of a target frequency.

[0025] In addition, to achieve the above object, the application further provides an alternating current charging pile, which comprises the ground line reliability detection circuit according to any one of the above embodiments, and is used for detecting whether the ground line of the alternating current charging pile is reliable.

[0026] The one or more technical solutions provided by the application have at least the following technical effects:

[0027] The existing three-phase five-wire system, that is, a power supply mechanism of three phase lines, one zero line and one ground line, is utilized, the zero line and the ground line are connected together and grounded at the transformer end, and the two are equipotential and separated from each other for laying, in a normal case, if the ground line is reliably grounded, the potential between the ground line and the zero line is zero, after the ground line reliability detection circuit is added, the voltage conversion unit arranged between the three phase lines and the ground line in the ground line reliability detection circuit first converts three-phase power output by the three phase lines into non-three-phase power and then outputs the non-three-phase power to the ground line, and the detection unit measures the voltage difference between the ground line and the zero line, if the voltage difference is small and close to zero, it indicates that the ground line and the zero line are equipotential, and the ground line is reliably grounded, if the voltage difference is greater than a first value, it indicates that the non-three-phase power converted by the three phase lines through the voltage conversion unit acts on the ground line, and the ground line does not release the energy of the potential through grounding, at this time, it is considered that the ground line is not reliably grounded, which may be caused by the disconnection of the ground line or the unreliable contact floating, therefore, prompt information representing that the ground line is not reliable is outputted to prompt the technician to further troubleshoot, the detection circuit of the application is simple and convenient for identifying the unreliable condition of the ground line, and the ground safety of the equipment such as the charging pile is improved. BRIEF DESCRIPTION OF DRAWINGS

[0028] The accompanying drawings, which are incorporated into and form part of the specification, illustrate embodiments consistent with the application and, together with the specification, serve to explain the principles of the application.

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the accompanying drawings needed to be used in the embodiments or prior art description will be briefly introduced as follows. Obviously, for those skilled in the art, the other drawings can also be obtained based on these drawings without any creative effort.

[0030] Figure 1 is one of the structural schematic diagrams of the ground wire reliability detection circuit proposed in the embodiments of the present application;

[0031] Figure 2 is the second structural schematic diagram of the ground wire reliability detection circuit proposed in the embodiments of the present application;

[0032] Figure 3 is the third structural schematic diagram of the ground wire reliability detection circuit proposed in the embodiments of the present application;

[0033] Figure 4 is the structural schematic diagram of the signal conversion unit in the ground wire reliability detection circuit proposed in the embodiments of the present application;

[0034] Figure 5 is the structural schematic diagram of the comparison unit in the ground wire reliability detection circuit proposed in the embodiments of the present application;

[0035] Figure 6 is the structural schematic diagram of the alternating current charging pile proposed in the embodiments of the present application.

[0036] Reference signs:

[0037] Explanation of reference signs:

[0038] 10, ground wire reliability detection circuit;

[0039] 101, voltage conversion unit; 102, detection unit;

[0040] 1021, signal conversion unit; 1022, comparison unit; 1023, processing unit;

[0041] 10211, first operational amplifier; 10221, second operational amplifier;

[0042] L1, first phase line; L2, second phase line; L3, third phase line; PE, ground wire; N, zero line;

[0043] C1, first capacitor; C2, second capacitor; C3, third capacitor; C4, fourth capacitor; C5, fifth capacitor; R1, first resistor; R2, second resistor; R3, third resistor; R4, fourth resistor; R5, fifth resistor; R6, sixth resistor; R7, seventh resistor; R8, eighth resistor; R9, ninth resistor.

[0044] The object, features, advantages and / or effects of the present application will be further illustrated in connection with embodiments described below, with reference to the accompanying drawings. DETAILED DESCRIPTION

[0045] It should be understood that the specific embodiments described herein merely exemplify the technical solutions of the present application, and are not intended to limit the present application.

[0046] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terminology used in the specification herein is for describing particular embodiments only and is not intended to be limiting of the application; the use herein of terms such as "comprise" and "have" and any variations thereof are intended to cover the presence of stated elements but not to preclude the presence of additional elements.

[0047] In the description of the embodiments of the present application, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the meaning of "a plurality of" is two or more, unless otherwise explicitly specified.

[0048] In the present application, the phrase "embodiments" means that the specific features, structures or properties described in connection with the embodiments can be included in at least one embodiment of the present application. The appearance of this phrase at various places in the specification does not necessarily mean the same embodiment, nor is it an independent or alternative embodiment to other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described in the present application can be combined with other embodiments.

[0049] In the description of the embodiments of the present application, the term "and / or" is only a description of the association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B, which can represent the three cases of A alone, A and B together, and B alone. In addition, the character " / " in this paper generally represents that the front and rear associated objects are in an "or" relationship.

[0050] In the description of the embodiments of the present application, unless otherwise explicitly specified and limited, the technical terms "mounting", "connecting", "connecting", "fixing" and the like should be understood in a broad sense, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanical connection, or it can be electrical connection; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0051] For better understanding of the technical solutions of the present application, the following will be described in detail in combination with the drawings of the specification and specific embodiments.

[0052] In the related art, according to the national standard, metal shell equipment such as charging piles needs reliable grounding, but the disconnection of the ground wire of the equipment often does not affect the operation of the equipment and is not easy to be identified, thereby existing a safety hazard. Therefore, how to effectively detect the poor grounding of the ground wire is a technical problem to be solved.

[0053] In view of the above problems, the ground wire reliability detection circuit provided by the embodiments of the present application aims to detect whether the ground wire of metal shell equipment such as alternating current charging piles is reliably grounded by using the three-phase five-wire system of the TN power supply system.

[0054] The ground wire reliability detection circuit provided by the embodiments of the present application will be described in detail below.

[0055] According to an aspect, Figure 1 is one of the structure diagrams of the ground wire reliability detection circuit provided by the embodiments of the present application, as Figure 1 shown, the ground wire reliability detection circuit 10 comprises a voltage conversion unit 101 and a detection unit 102;

[0056] The voltage conversion unit 101 is arranged between three phase lines (i.e. L1, L2, L3 in the figure) and a ground wire (i.e. PE in the figure), and is used to convert three-phase electricity output by the three phase lines L1, L2, L3 into non-three-phase electricity and then output to the ground wire PE.

[0057] The detection unit 102 is used to measure the voltage difference between the ground wire PE and a zero line (i.e. N line in the figure), and output prompt information for indicating that the ground wire PE is unreliable when the voltage difference is greater than a first value.

[0058] It should be noted that for the three-phase five-wire system of the TN (zero-protection system) power supply system, there are usually three phase lines, one zero line and one ground wire;

[0059] Among them, the three phase lines are used to output three-phase alternating current, which is used to supply alternating current to electrical equipment such as alternating current charging piles; the zero line is also called the neutral line, and when the three-phase load is symmetrical, the current vector sum of the neutral line is zero, but when it is asymmetrical, there will be current passing through; the ground wire is used for grounding protection to ensure that the equipment shell is not electrified, and plays a role in safety protection.

[0060] Generally, the zero line and the ground line are connected together and grounded at the transformer end of the power system, and the two are equipotential and insulated from each other and are laid separately. If the ground line is reliably grounded, even if there is a leakage current flowing into the ground line, the ground line can release energy due to reliable grounding, thereby ensuring that the ground line and the zero line are equipotential, and effectively ensuring the safety of the electrical equipment; however, if the ground line is not grounded well, for example, the ground line is disconnected at the wiring of the electrical equipment, or the contact is unreliable and floating, in this case, if there is a leakage current flowing into the ground line, the ground line cannot release energy, at this time, a potential difference is formed between the ground line and the zero line, which seriously affects the safety of the user using the electrical equipment.

[0061] Based on the above idea, the ground line reliability detection circuit provided in the embodiments of the present application utilizes three-phase alternating current output by three phase lines in a three-phase five-wire system to generate the above leakage current.

[0062] In terms of specific circuit connection structure, the voltage conversion unit 101 is arranged between the three phase lines (L1, L2, L3) and the ground line PE, and the three-phase power output by the three phase lines is converted into non-three-phase power by the voltage conversion unit 101 and output to the ground line PE, so as to generate a leakage current on the ground line PE, and then the size of the voltage difference between the ground line PE and the zero line N is measured to determine whether the ground line is reliably grounded;

[0063] After the leakage current is generated on the ground line PE, if the ground line PE is reliably grounded, the ground line PE can release the energy corresponding to the leakage current, and finally the voltage difference between the ground line PE and the zero line N is measured to be almost 0, and it is considered that the two are commonly grounded and equipotential; if the ground line PE is not reliably grounded, the ground line PE cannot release the energy corresponding to the leakage current, and finally the voltage difference between the ground line PE and the zero line N is measured to be large, and when the voltage difference is greater than a first value, it is considered that the ground line PE is unreliable, and a prompt information for indicating that the ground line is unreliable is output, so as to be further investigated and maintained by the technician.

[0064] In some embodiments, when the detection unit 102 detects that the above voltage difference is greater than the first value, the warning light buzzer or the like can also be controlled to alarm and feedback.

[0065] It should be noted that the above first value can be set according to actual conditions, for example, by referring to the voltage and other parameters of the non-three-phase power converted and output by the voltage conversion unit, and the present application does not limit this.

[0066] This application provides a ground wire reliability detection circuit that utilizes an existing three-phase five-wire power supply system, namely, three phase wires, one neutral wire, and one ground wire. The neutral wire and ground wire are connected together at the transformer terminal and grounded. They are of equal potential and insulated from each other, laid separately. Normally, if the ground wire is reliably grounded, the potential between the ground wire and the neutral wire is zero. This application adds a ground wire reliability detection circuit, in which a voltage conversion unit located between the three phase wires and the ground wire first converts the three-phase electricity output from the three phase wires into non-three-phase electricity before outputting it to the ground wire. The detection unit measures the voltage difference between the ground wire and the neutral wire. If the voltage difference is zero... If the voltage difference is small and close to zero, it indicates that the ground wire and the neutral wire are at the same potential, and the ground wire is reliably grounded. If the voltage difference is greater than the first value, it indicates that after the non-three-phase electricity converted by the three phase wires through the voltage conversion unit is applied to the ground wire, the ground wire does not release the energy of the potential through grounding. At this time, it is considered that the ground wire is not reliably grounded, possibly due to unreliable situations such as ground wire disconnection or unreliable contact. Therefore, at this time, an indication of unreliable ground wire is output to prompt technicians to further investigate. The detection circuit of this application is simple and easy to identify unreliable ground wire situations, improving the grounding safety of equipment such as charging piles.

[0067] According to some embodiments of this application, a specific implementation of the voltage conversion unit is provided. Figure 2 This is a second schematic diagram of the ground wire reliability detection circuit proposed in the embodiments of this application, as shown below. Figure 2 As shown, a first capacitor C1 is connected between the neutral line N and the ground line PE. The three phase lines include the first phase line L1, the second phase line L2 and the third phase line L3. The voltage conversion unit 101 includes a second capacitor C2, a third capacitor C3 and a fourth capacitor C4.

[0068] The second capacitor C2 is connected between the first phase line L1 and the ground line PE, the third capacitor C3 is connected between the second phase line L2 and the ground line PE, and the fourth capacitor C4 is connected between the third phase line L3 and the ground line PE.

[0069] The capacitance values ​​of the second capacitor C2, the third capacitor C3, and the fourth capacitor C4 are not all the same.

[0070] Specifically, for the voltage conversion unit 101, the first phase line L1, the second phase line L2, and the third phase line L3 are connected to the ground line PE through the second capacitor C2, the third capacitor C3, and the fourth capacitor C4, respectively. The capacitors are set here because they can conduct alternating current. Furthermore, in this application, the capacitance values ​​of the second capacitor C2, the third capacitor C3, and the fourth capacitor C4 are not all the same, so that the three-phase power output from the three phase lines is converted into non-three-phase power, thereby generating leakage current on the ground line PE, and thus detecting whether the ground line PE is reliably grounded.

[0071] It should be noted that the capacitance values of the second capacitor C2, the third capacitor C3 and the fourth capacitor C4 can be set to be all different, or only two of them are the same, and the specific capacitance values can be set according to actual conditions, and the present application does not limit this.

[0072] It should also be noted that the capacitance value of the first capacitor C1 set between the neutral line N and the ground line PE can be set according to actual conditions, and the relationship between the capacitance values of the second capacitor C2, the third capacitor C3 and the fourth capacitor C4 is not limited.

[0073] In some embodiments, the first capacitor C1, the second capacitor C2, the third capacitor C3 and the fourth capacitor C4 adopt Y capacitors.

[0074] Specifically, the above-mentioned capacitors all adopt Y capacitors in order to meet safety regulations. Y capacitors can play a power filter role, especially a common mode interference filter role.

[0075] In some embodiments, other capacitors or capacitor-related circuits can also be used on the basis of meeting safety regulations, and the present application does not limit this.

[0076] According to some embodiments of the present application, a specific implementation of a detection unit is provided. Figure 3 FIG. 3 is a structural schematic diagram of a ground line reliability detection circuit according to an embodiment of the present application, and Figure 3 As shown in FIG. 3, the detection unit 102 includes a signal conversion unit 1021, a comparison unit 1022 and a processing unit 1023.

[0077] The signal conversion unit 1021 is configured to convert the voltage difference into a target voltage within a voltage range supported by the comparison unit 1022, and output the target voltage to the comparison unit 1022.

[0078] The comparison unit 1022 is configured to compare the target voltage with a pre-set reference voltage, and output a target signal to the processing unit 1023 in the case that the target voltage is greater than the reference voltage.

[0079] The processing unit 1023 is configured to output the prompt information after receiving the target signal.

[0080] Specifically, for the detection unit 102, the sampled voltage difference is first converted by the signal conversion unit 1021 to adapt to the voltage range supported by the comparison unit 1022 for processing, specifically converted into a target voltage, and output to the comparison unit 1022, and the comparison unit 1022 compares the target voltage with a pre-set reference voltage, where the reference voltage can correspond to the first value, and if the target voltage is greater than the reference voltage, it is considered that the above-mentioned voltage difference is greater than the first value, at which time the target signal is output to the processing unit 1023, and the processing unit 1023 outputs prompt information after receiving the target signal to prompt that the ground is unreliable.

[0081] In some embodiments, if the comparison unit 1022 determines that the target voltage is less than or equal to the reference voltage, the above-mentioned voltage difference is less than or equal to the first value, and it is considered that the ground is reliably grounded, at which time the comparison unit 1022 prohibits outputting the target signal to the processing unit 1023, and the processing unit 1023 prohibits outputting the prompt information when no target signal is received.

[0082] In some embodiments, the processing unit 1023 can be a microcontroller unit (MCU), and the target signal can be a square wave signal of a target frequency.

[0083] It should be noted that the above-mentioned target frequency can be set according to actual conditions, for example, 50Hz, which is not limited in the present application.

[0084] According to some embodiments of the present application, a specific implementation of the signal conversion unit 1021 in the detection unit 102 is provided. Figure 4 is a structural diagram of the signal conversion unit in the ground reliability detection circuit according to the embodiments of the present application, as Figure 4 shown, the signal conversion unit 1021 includes a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, and a first operational amplifier 10211.

[0085] The opposite input end of the first operational amplifier 10211 is connected to the neutral line N through the first resistor R1, the same input end of the first operational amplifier 10211 is connected to the ground PE through the second resistor R2, the opposite input end of the first operational amplifier 10211 is also connected to the output end of the first operational amplifier 10211 through the third resistor R3, the same input end of the first operational amplifier 10211 is also connected to a high level through the fourth resistor R4 and grounded through the fifth resistor R5, and the output end of the first operational amplifier 10211 serves as the output end of the signal conversion unit 1021.

[0086] It should be noted that the resistance values of the first resistor R1, the second resistor R2, the third resistor R3, the fourth resistor R4, and the fifth resistor R5, and the model of the first operational amplifier 10211 can be set according to actual conditions, for example, by referring to the voltage range supported by the comparison unit 1022, the reference voltage, and the like, and the present application does not limit this.

[0087] It should also be noted that the specific implementation of the signal conversion unit 1021 provided in the present application is only an example of an implementation, and other implementations of the signal conversion unit 1021 described above are also within the protection scope of the present application.

[0088] In some embodiments, the high level to which the fourth resistor R4 is connected can be set to a direct current level of 3.3V.

[0089] In some embodiments, the detection unit 102 can further include an isolation unit, and the inverting input terminal of the first operational amplifier 10211 is connected to the neutral line N through the first resistor R1 and the isolation unit.

[0090] Specifically, the detection unit 102 can further include an isolation unit to isolate the neutral line N from the detection unit 102, which can effectively protect the detection unit 102 from damage and improve the stability of the operation of the detection unit 102.

[0091] In some embodiments, as shown in Figure 4 the isolation unit can include a fifth capacitor C5.

[0092] Specifically, the isolation unit can include a fifth capacitor C5, and the fifth capacitor C5 can also be a Y capacitor, which can be set according to actual conditions.

[0093] In other embodiments, the isolation unit can be an optoelectronic coupling unit.

[0094] According to some embodiments of the present application, a specific implementation of the comparison unit 1022 in the detection unit 102 is provided. Figure 5 is a structural diagram of a comparison unit in a ground line reliability detection circuit according to an embodiment of the present application, as shown in Figure 5 the comparison unit 1022 includes a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, a ninth resistor R9, and a second operational amplifier 10221.

[0095] The same direction input end of the second operational amplifier 10221 is used for receiving the target voltage, the opposite direction input end of the second operational amplifier 10221 is connected to high level through the sixth resistance R6 and grounded through the seventh resistance R7, which is used for providing the reference voltage, the same direction input end of the second operational amplifier 10221 is also connected to the output end of the second operational amplifier 10221 through the eighth resistance R8, the output end of the second operational amplifier 10221 is connected to high level through the ninth resistance R9, and the output end of the second operational amplifier 10221 is used as the output end of the comparison unit 1022.

[0096] It should be noted that the resistance values of the sixth resistance R6, the seventh resistance R7, the eighth resistance R8 and the ninth resistance R9, and the model of the second operational amplifier 10221 can be set according to actual conditions, for example, the voltage range supported by the processing unit 1023, the reference voltage, etc., which are not limited in the present application.

[0097] In some embodiments, the reference voltage is obtained by voltage division of the sixth resistance R6 and the seventh resistance R7, and the size of the reference voltage can be adjusted by adjusting the resistance values of the sixth resistance R6 and the seventh resistance R7.

[0098] It should be further noted that the specific implementation of the comparison unit 1022 provided in the present application is only an example implementation, and other implementations of the comparison unit 1022 described above are also within the protection scope of the present application.

[0099] In some embodiments, the high level to which the sixth resistance R6 and the ninth resistance R9 are connected can be set to 3.3V DC level.

[0100] According to another aspect, the embodiments of the present application also provide an alternating current charging pile, which comprises the ground line reliability detection circuit according to any one of the above embodiments, and is used for detecting whether the ground line of the alternating current charging pile is reliable.

[0101] It should be noted that the alternating current charging pile is connected to three phase lines, one zero line and one ground line in the above embodiments through a charging pile power supply connection terminal, wherein the three phase lines are used for alternating current power supply to the alternating current charging pile.

[0102] It should be further noted that the alternating current charging pile can be used to charge electric vehicles, electric bicycles and the like, and the charging object is not limited in the present application.

[0103] The following illustrates the ground line reliability detection circuit and the alternating current charging pile provided by the embodiments of the present application.

[0104] The basic principle of ground wire reliability detection of the alternating current charging pile is as follows: using the three-phase five-wire system of the power supply TN system, the N line and the PE line are connected together at the transformer end and grounded, and the two are equipotential and insulated from each other; Y capacitor is used for voltage division, when the PE line is disconnected, there is a voltage difference between the N line and the PE line, based on which, the voltage difference between the N line and the PE line in the charging pile is detected to determine whether the ground wire is reliably grounded.

[0105] Specifically, Figure 6 is a structural schematic diagram of an alternating current charging pile proposed by the embodiment of the present application, as Figure 6 shown, the charging pile inputs three-phase five-wire through the charging pile power supply connection terminal, and in the case of normal grounding, the N line and the PE line do not have a potential difference because they are commonly grounded at the remote transformer.

[0106] When the PE line of the charging pile is disconnected at ① or floating and unreliable contact, because the phase line and the N line are connected with Y capacitors of different values to the PE line, the PE line in the charging pile will be pulled up due to the Y capacitor leakage current of the phase line, thereby existing a potential to the N line. The potential between the PE line and the N line is biased using an operational amplifier, and compared with a reference voltage, and a square wave is output from the operational amplifier to the MCU. When the MCU detects a 50Hz square wave, the warning light buzzer and the like are controlled to alarm and feedback, thereby realizing effective detection and prompt of poor ground wire grounding and improving the power utilization safety of the alternating current charging pile.

[0107] It should be noted that the above examples are only used to understand the present application and do not constitute a limitation on the ground wire reliability detection circuit of the present application, and more forms of simple transformation based on this technical concept are all within the protection scope of the present application.

[0108] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art can easily think of changes or replacements within the technical range disclosed by the present application, which should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

[0109] The above is only part of the embodiments of the present application, and does not limit the patent scope of the present application, and any equivalent structural transformation based on the technical concept of the present application and the contents of the drawings, or direct / indirect application in other related technical fields are all included in the patent protection scope of the present application.

Claims

1. A ground wire reliability detection circuit, characterized in that, The circuit includes: a voltage conversion unit and a detection unit; The voltage conversion unit is located between the three phase lines and the ground line, and is used to convert the three-phase electricity output from the three phase lines into non-three-phase electricity and then output it to the ground line. The detection unit is used to measure the voltage difference between the ground wire and the neutral wire, and outputs a prompt message indicating that the ground wire is unreliable when the voltage difference is greater than a first value.

2. The circuit as described in claim 1, characterized in that, A first capacitor is connected between the neutral wire and the ground wire; the three phase wires include a first phase wire, a second phase wire, and a third phase wire; and the voltage conversion unit includes a second capacitor, a third capacitor, and a fourth capacitor. The second capacitor is connected between the first phase line and the ground line, the third capacitor is connected between the second phase line and the ground line, and the fourth capacitor is connected between the third phase line and the ground line. The capacitance values ​​of the second capacitor, the third capacitor, and the fourth capacitor are not all the same.

3. The circuit as described in claim 2, characterized in that, The first capacitor, the second capacitor, the third capacitor, and the fourth capacitor are Y capacitors.

4. The circuit as described in any one of claims 1 to 3, characterized in that, The detection unit includes a signal conversion unit, a comparison unit, and a processing unit; The signal conversion unit is used to convert the voltage difference into a target voltage within the voltage range supported by the comparison unit, and output the target voltage to the comparison unit; The comparison unit is used to compare the target voltage with a preset reference voltage, and outputs a target signal to the processing unit when the target voltage is greater than the reference voltage. The processing unit is used to output the prompt information after receiving the target signal.

5. The circuit as described in claim 4, characterized in that, The signal conversion unit includes: a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, and a first operational amplifier; The inverting input terminal of the first operational amplifier is connected to the neutral line through the first resistor, the non-inverting input terminal of the first operational amplifier is connected to the ground line through the second resistor, the inverting input terminal of the first operational amplifier is also connected to the output terminal of the first operational amplifier through the third resistor, the non-inverting input terminal of the first operational amplifier is also connected to a high level through the fourth resistor and grounded through the fifth resistor, and the output terminal of the first operational amplifier serves as the output terminal of the signal conversion unit.

6. The circuit as described in claim 5, characterized in that, The detection unit further includes an isolation unit, and the inverting input terminal of the first operational amplifier is connected to the neutral line through the first resistor and the isolation unit.

7. The circuit as described in claim 6, characterized in that, The isolation unit includes a fifth capacitor.

8. The circuit as described in claim 4, characterized in that, The comparison unit includes: a sixth resistor, a seventh resistor, an eighth resistor, a ninth resistor, and a second operational amplifier; The non-inverting input of the second operational amplifier is used to receive the target voltage. The inverting input of the second operational amplifier is connected to a high level through the sixth resistor and grounded through the seventh resistor to provide the reference voltage. The non-inverting input of the second operational amplifier is also connected to the output of the second operational amplifier through the eighth resistor. The output of the second operational amplifier is connected to a high level through the ninth resistor, and the output of the second operational amplifier serves as the output of the comparator unit.

9. The circuit as described in claim 4, characterized in that, The processing unit is a microcontroller unit, and the target signal is a square wave signal at the target frequency.

10. An AC charging pile, characterized in that, The AC charging pile includes a ground wire reliability detection circuit as described in any one of claims 1 to 9, used to detect whether the ground wire of the AC charging pile is reliable.

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