Fault detection circuit of lightning protection circuit of alternating current charging pile and alternating current charging pile

Abstract

The utility model relates to a fault detection circuit of an AC charging pile lightning protection circuit and an AC charging pile, and belongs to the field of electric automobile charging equipment. The fault detection circuit comprises a first temperature fuse, a second temperature fuse, a current type voltage transformer, a first resistor, a second resistor and a metering chip. The first temperature fuse is connected in series between the zero line and the first piezoresistor, and the second temperature fuse is connected in series between the live line and the second piezoresistor; a primary winding of the current type voltage transformer is respectively connected with nodes between the piezoresistor and the temperature fuse; the secondary winding is connected with the voltage input end of the metering chip and is connected with the first resistor and the second resistor in series. The fault detection circuit provided by the utility model collects and analyzes whether the voltage in the lightning protection circuit is abnormal so as to judge whether the lightning protection circuit of the AC charging pile works normally, so that the fault of the lightning protection circuit can be found in time and fault reminding can be provided.

Description

Technical Field

[0001] The utility model belongs to the field of electric vehicle charging equipment, and relates to a fault detection circuit for a lightning protection circuit of an AC charging pile and an AC charging pile. Background Art

[0002] The wide promotion of new energy vehicles has driven the development of AC charging piles and DC charging piles for electric vehicles. Generally, DC charging piles and AC charging piles are built outdoors. The charging piles built outdoors work in a live state. When there is lightning activity nearby, the lightning current generates a strong electromagnetic wave, and an extremely high pulse voltage is induced on the power line, which may cause the insulation breakdown of the devices in the charging pile and the phase-to-phase short circuit in severe cases, and even cause the charging pile to catch fire in severe cases, especially serious for AC charging piles. Therefore, it is essential to add a lightning protection circuit to the AC charging pile. The damage of the lightning protection circuit of the AC charging pile is very likely to cause damage to the protected AC charging pile and the electric vehicle being charged. Therefore, it is of great significance to be able to accurately detect whether the lightning protection circuit of the AC charging pile is working properly. Summary of the Utility Model

[0003] The purpose of the utility model is to overcome the deficiencies in the prior art and provide a fault detection circuit for a lightning protection circuit of an AC charging pile and an AC charging pile, which can accurately and timely detect the lightning protection circuit fault and provide a fault reminder.

[0004] To achieve the above purpose, the utility model is implemented by the following technical solutions:

[0005] On the one hand, the utility model provides a fault detection circuit for a lightning protection circuit of an AC charging pile. The lightning protection circuit of the AC charging pile includes a first varistor connected to the AC input neutral line of the charging pile and a second varistor connected to the AC input live line of the charging pile;

[0006] The fault detection circuit includes: a first temperature fuse, a second temperature fuse, a current-type voltage transformer, a first resistor, a second resistor, and a metering chip;

[0007] The first temperature fuse is connected in series between the neutral line and the first varistor; the second temperature fuse is connected in series between the live line and the second varistor;

[0008] The first primary winding of the current-type voltage transformer is connected to a first node between the first varistor and the first temperature fuse; the second primary winding of the current-type voltage transformer is connected to a second node between the second varistor and the second temperature fuse;

[0009] One end of the first resistor is connected to the first secondary winding of the current-type voltage transformer, and the other end is connected to one end of the second resistor. The other end of the second resistor is connected to the second secondary winding of the current-type voltage transformer;

[0010] The first secondary winding is connected to the first voltage input terminal of the metering chip; the second secondary winding is connected to the second voltage input terminal of the metering chip.

[0011] Further, the first varistor and the first thermal fuse are closely attached and encapsulated; the second varistor and the second thermal fuse are closely attached and encapsulated.

[0012] Further, it further includes: a third resistor; the third resistor is connected in series between the second primary winding and the second node.

[0013] Further, it further includes: a plurality of third resistors; the plurality of third resistors are connected in series between the second primary winding and the second node in sequence.

[0014] Further, six third resistors are provided.

[0015] Further, it further includes: a fourth resistor and a fifth resistor;

[0016] The fourth resistor is connected in series between the first secondary winding and the first voltage input terminal of the metering chip, and the fifth resistor is connected in series between the second secondary winding and the second voltage input terminal of the metering chip.

[0017] Further, it further includes: a first capacitor and a second capacitor;

[0018] The connection line between the first resistor and the second resistor is connected to the ground terminal;

[0019] One end of the first capacitor is connected to the third node between the fourth resistor and the first voltage input terminal of the metering chip, and the other end is connected to the fourth node between the first resistor and the ground terminal;

[0020] One end of the second capacitor is connected to the fifth node between the fifth resistor and the second voltage input terminal of the metering chip, and the other end is connected to the fourth node.

[0021] Further, it further includes: a main control CPU connected to the metering chip.

[0022] On the other hand, the present invention also provides an AC charging pile, including the fault detection circuit of the above AC charging pile lightning protection circuit.

[0023] Compared with the prior art, the beneficial effects achieved by the present utility model are as follows:

[0024] For the fault detection circuit of the lightning protection circuit of the AC charging pile provided by the present utility model, the varistor and the thermal fuse are tightly encapsulated together. Therefore, when the varistor conducts overvoltage, the heat generated by the varistor due to the strong current will be quickly conducted to the thermal fuse, causing the thermal fuse to blow, and then resulting in the voltage collected by the metering chip being zero. By collecting the voltage in the lightning protection circuit through the metering chip, the main control CPU analyzes whether the voltage in the lightning protection circuit is abnormal, so as to judge whether the lightning protection circuit of the AC charging pile is working properly, can timely detect the fault of the lightning protection circuit, and issue a fault reminder. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 FIG. is a schematic structural diagram of a fault detection circuit of a lightning protection circuit of an AC charging pile provided by an embodiment of the present utility model. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0026] The technical solution of the present utility model will be described in detail below with reference to the drawings and specific embodiments. The same reference numerals in the drawings denote the same or similar components or parts. Those skilled in the art should understand that these drawings are not necessarily drawn to scale. The embodiments of the present application and the specific features in the embodiments are detailed descriptions of the technical solution of the present application, rather than limitations on the technical solution of the present application. Without conflict, the technical features in the embodiments of the present application and the embodiments can be combined with each other.

[0027] In the description of the present utility model, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present utility model. In addition, the term "and / or" in this article is only a description of the association relationship of the associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this article generally represents an "or" relationship between the associated objects before and after.

[0028] In the description of the present utility model, it should be noted that unless otherwise clearly specified and defined, the terms "installation", "connection", and "coupling" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present utility model can be understood through specific circumstances.

[0029] Embodiment 1:

[0030] As Figure 1 shown, the embodiment of the present utility model provides a fault detection circuit for a lightning protection circuit of an AC charging pile, which is applicable to various lightning protection circuits of charging piles. In the embodiment of the present utility model, taking the Figure 1 shown lightning protection circuit 100 of the AC charging pile as an example, it is composed of a first varistor RV1, a second varistor RV2, and a gas discharge tube GDT1. Among them, the first varistor RV1 is connected to the AC input neutral line N of the charging pile, and the second varistor RV2 is connected to the AC input live wire L of the charging pile. The varistor and the gas discharge tube are an ideal lightning protection combination. The varistor can cut off the subsequent current generated after the gas discharge tube breaks down to prevent the input circuit from being short-circuited due to excessive subsequent current, and the gas discharge tube prevents the leakage current of the varistor to meet the safety regulations requirements.

[0031] The fault detection circuit 200 of the present utility model includes: a first thermal fuse TF1, a second thermal fuse TF2, a current-type voltage transformer PT1, a first resistor R7, a second resistor R8, and a metering chip.

[0032] One end of the first thermal fuse TF1 is connected to the neutral line N, and the other end is connected to the first varistor RV1; one end of the second thermal fuse TF2 is connected to the live wire L, and the other end is connected to the second varistor RV2.

[0033] The present utility model encapsulates and fixes the first varistor RV1 and the first thermal fuse TF1 together, and encapsulates and fixes the second varistor RV2 and the second thermal fuse TF2 together, while ensuring that the set temperature of the first thermal fuse TF1 is the upper limit operating temperature of the first varistor RV1, and the set temperature of the second thermal fuse TF2 is the upper limit operating temperature of the second varistor RV2, so that the varistor and the thermal fuse in close contact have good thermal coupling.

[0034] The first primary winding (pin 2) of the current-type voltage transformer PT1 is connected to the first node between the first varistor RV1 and the first thermal fuse TF1.

[0035] The second primary winding (pin 1) of the current-type voltage transformer PT1 is connected to the second node between the second varistor RV2 and the second thermal fuse TF2.

[0036] In the present utility model, a current-limiting resistor is composed of six series-connected third resistors R1, R2, R3, R4, R5, and R6, and is connected in series between the second primary winding of the current-type voltage transformer PT1 and the second node.

[0037] The first secondary winding (pin 3) of the current-type voltage transformer PT1, the first resistor R7, the second resistor R8, and the second secondary winding (pin 4) of the current-type voltage transformer PT1 are connected in series in sequence, so as to convert the milliampere-level current output by the first secondary winding and the second secondary winding of the current-type voltage transformer PT1 into a voltage.

[0038] In this embodiment, the sixth node between the first secondary winding and the first resistor R7 is connected to the negative analog VN pin of the voltage channel of the metering chip, and the seventh node between the second secondary winding and the second resistor R8 is connected to the positive analog VP pin of the voltage channel of the metering chip.

[0039] The fault detection circuit 200 of the present utility model further includes: a fourth resistor R9, a fifth resistor R10, a first capacitor C1, and a second capacitor C2.

[0040] Wherein, the fourth resistor R9 is connected in series between the sixth node and the metering chip, and the fifth resistor R10 is connected in series between the seventh node and the metering chip.

[0041] The connection line between the first resistor R7 and the second resistor R8 is connected to the ground terminal GND; one end of the first capacitor C1 is connected to the third node between the fourth resistor R9 and the metering chip, and the other end is connected to the fourth node between the connection line between the first resistor R7 and the second resistor R8 and the ground terminal GND; one end of the second capacitor C2 is connected to the fifth node between the fifth resistor R10 and the metering chip, and the other end is connected to the fourth node.

[0042] The fourth resistor R9 and the first capacitor C1, and the fifth resistor R10 and the second capacitor C2 respectively form anti-aliasing filters to reduce the error and distortion of the voltage signal input to the metering chip.

[0043] The fault detection circuit 200 of the present utility model further includes: a main control CPU connected to the metering chip. The metering chip used in the present utility model is an application-specific integrated circuit for power metering. The AC voltage signal is collected by the metering chip and transmitted to the main control CPU. The main control CPU can judge the on-off states of the first thermal fuse TF1 and the second thermal fuse TF2 according to the magnitude of the AC voltage input by the metering chip.

[0044] When there is no lightning surge, the first varistor RV1 and the second varistor RV2 operate in a non-breakdown state, that is, in an open-circuit state, the resistance is extremely large, the current is extremely small, and thus the heat generated is also extremely small. Since the varistor is encapsulated together with the thermal fuse, the heat of the varistor will be quickly conducted to the thermal fuse. The set temperatures of the first thermal fuse TF1 and the second thermal fuse TF2 are the upper limit operating temperatures of the first varistor RV1 and the second varistor RV2. Therefore, when there is a lightning surge, when the voltage is too high and the first varistor RV1 and the second varistor RV2 are overvoltage-conducted, a strong current will cause strong heating. When the temperature generated by the heating exceeds the upper limit operating temperatures of the first varistor RV1 and the second varistor RV2, that is, exceeds the set temperatures of the first thermal fuse TF1 and the second thermal fuse TF2 which are tightly fixed to them, the first thermal fuse TF1 and the second thermal fuse TF2 will blow. At this time, the AC input voltage of the AC charging pile cannot be transmitted to the primary of the current-type voltage transformer PT1, the secondary output of the current-type voltage transformer PT1 is zero, and further the voltage collected by the metering chip is zero. Based on this, the main control CPU can judge that the lightning protection circuit of the AC charging pile has a fault and issue a fault reminder.

[0045] Embodiment 2:

[0046] Based on the same concept as Embodiment 1, the embodiment of the present utility model further provides an AC charging pile, which includes the fault detection circuit of the above-mentioned lightning protection circuit of the AC charging pile.

[0047] The above are only the preferred embodiments of the present utility model. It should be noted that for those of ordinary skill in the art, without departing from the technical principle of the present utility model, several improvements and deformations can still be made, and these improvements and deformations should also be regarded as the protection scope of the present disclosure / this application.

Claims

1. A fault detection circuit for a lightning protection circuit of an AC charging pile, characterized in that, The lightning protection circuit of the AC charging pile includes a first varistor connected to the neutral line of the AC input of the charging pile, and a second varistor connected to the live wire of the AC input of the charging pile; The fault detection circuit includes: a first temperature fuse, a second temperature fuse, a current-type voltage transformer, a first resistor, a second resistor, and a metering chip; The first temperature fuse is connected in series between the neutral line and the first varistor; the second temperature fuse is connected in series between the live wire and the second varistor; The first primary winding of the current-type voltage transformer is connected to the first node between the first varistor and the first temperature fuse; the second primary winding of the current-type voltage transformer is connected to the second node between the second varistor and the second temperature fuse; One end of the first resistor is connected to the first secondary winding of the current-type voltage transformer, and the other end is connected to one end of the second resistor, and the other end of the second resistor is connected to the second secondary winding of the current-type voltage transformer; The first secondary winding is connected to the first voltage input terminal of the metering chip; the second secondary winding is connected to the second voltage input terminal of the metering chip.

2. The fault detection circuit of the lightning protection circuit for the AC charging pile according to claim 1, characterized in that The first varistor and the first temperature fuse are closely attached and encapsulated; the second varistor and the second temperature fuse are closely attached and encapsulated.

3. The fault detection circuit of the lightning protection circuit for the AC charging pile according to claim 1, characterized in that, It further includes: A third resistor; the third resistor is connected in series between the second primary winding and the second node.

4. The fault detection circuit of the lightning protection circuit for an AC charging pile according to claim 1, characterized in that, It further includes: A plurality of third resistors; The plurality of third resistors are connected in series in sequence between the second primary winding and the second node.

5. The fault detection circuit of the lightning protection circuit for the AC charging pile according to claim 4, characterized in that, Six third resistors are provided.

6. The fault detection circuit of the lightning protection circuit for the AC charging pile according to claim 1, characterized in that, It further includes: A fourth resistor and a fifth resistor; The fourth resistor is connected in series between the first secondary winding and the first voltage input terminal of the metering chip, and the fifth resistor is connected in series between the second secondary winding and the second voltage input terminal of the metering chip.

7. The fault detection circuit of the lightning protection circuit for the AC charging pile according to claim 6, characterized in that, It further includes: a first capacitor and a second capacitor; The connection line between the first resistor and the second resistor is connected to the ground terminal; One end of the first capacitor is connected to the third node between the fourth resistor and the first voltage input terminal of the metering chip, and the other end is connected to the fourth node between the first resistor and the ground terminal; One end of the second capacitor is connected to the fifth node between the fifth resistor and the second voltage input terminal of the metering chip, and the other end is connected to the fourth node.

8. The fault detection circuit of the lightning protection circuit for the AC charging pile according to claim 1, characterized in that It further includes: A main control CPU connected to the metering chip.

9. An AC charging pile, characterized in that, A fault detection circuit including the lightning protection circuit of the AC charging pile according to any one of claims 1 to 8.

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