Alternating current charging pile and wire breakage detection system thereof

Abstract

An alternating current charging pile and a broken line detection system thereof, the broken line detection system comprising: a first switch, a first resistor, a first voltage source, a sampling resistor and a controller, wherein: the first switch is connected with a PEN protection line of the alternating current charging pile at a first end thereof and coupled with a first end of the first resistor at a second end thereof; the first resistor is coupled with a high potential end of the first voltage source at a second end thereof; the first voltage source is coupled with a first end of the sampling resistor at a low potential end thereof; a second end of the sampling resistor is grounded; the controller is coupled with a control end of the first switch and used for controlling the first switch to be turned on in a detection period; and used for determining that the PEN protection loop is broken when it is detected that a resistance between the PEN protection line and a ground wire is greater than a preset safety resistance threshold; and the first voltage source outputs a first voltage and a second voltage at a periodic interval in the detection period. The above scheme can accurately determine whether the PEN protection line is disconnected, thereby improving the use safety of the alternating current charging pile.

Description

Technical Field

[0001] This utility model relates to the field of charging pile technology, and in particular to the design of an AC charging pile and its disconnection detection system. Background Technology

[0002] AC charging stations are connected to the AC power grid to provide AC charging services for electric vehicles. In a directly grounded neutral system (TN-C), the protective earth (PE) conductor and the neutral connection conductor (N) are the same conductor (PEN protective conductor).

[0003] In the field of AC charging piles, voltage comparison is typically used to detect open circuits in the PEN protection line of a TN-C system. A virtual N-phase voltage is established by using resistors and capacitors to connect the three live wires (L1, L2, and L3) of the AC power grid. The difference between the virtual N-phase voltage and the voltage on the PEN protection line is used to determine whether the PEN protection circuit containing the PEN protection line is open.

[0004] However, when the three-phase live wires of the AC power grid are unbalanced, the virtual N-phase voltage is unstable, making it impossible to accurately determine whether the PEN protection circuit is disconnected. Utility Model Content

[0005] In view of this, the purpose of this application is at least to provide an AC charging pile and its disconnection detection system, which can accurately determine whether the PEN protection line is disconnected, thereby improving the safety of AC charging piles.

[0006] To achieve the above objectives, the technical solution provided in this application is as follows:

[0007] In a first aspect of this application, a disconnection detection system for an AC charging pile is provided, comprising: a first switch, a first resistor, a first voltage source, a sampling resistor, and a controller, wherein the first switch, the first resistor, the first voltage source, and the sampling resistor are connected in series, wherein: the first terminal of the first switch is connected to the PEN protection line of the AC charging pile, and the second terminal of the first switch is coupled to the first terminal of the first resistor; the second terminal of the first resistor is coupled to the high-potential terminal of the first voltage source; the low-potential terminal of the first voltage source is coupled to the first terminal of the sampling resistor; the second terminal of the sampling resistor is grounded; the controller is coupled to the control terminal of the first switch and is used to control the first switch to conduct during a detection period; and to determine that the PEN protection circuit is disconnected when the resistance between the PEN protection line and the ground line is greater than a preset safety resistance threshold; wherein, during the detection period, the first voltage source periodically outputs a first voltage and a second voltage at intervals, and the first voltage, the second voltage, and the voltage on the PEN protection line are all unequal.

[0008] Optionally, the open circuit detection system further includes: a voltage sampling circuit, the input of which is coupled to the first end of the sampling resistor, and the output of which is coupled to the controller, to acquire the voltage at the first end of the sampling resistor and output it to the controller.

[0009] Optionally, the open circuit detection system further includes: a reference voltage source, the low potential end of which is coupled to the low potential end of the first voltage source, and the high potential end of which is coupled to the first end of the sampling resistor, and outputs a constant reference voltage to the first end of the sampling resistor.

[0010] Optionally, the controller is coupled to the first voltage source and outputs a voltage control signal to the first voltage source during the detection period; the first voltage source, in response to receiving the voltage control signal, outputs the first voltage and the second voltage at intervals during the detection period.

[0011] Optionally, the disconnection detection system further includes: a first communication device coupled to the controller, for receiving a disconnection prompt signal output by the controller and forwarding the disconnection prompt signal to a pre-associated electronic device.

[0012] Optionally, the disconnection detection system further includes: a first alarm device, coupled to the controller, receiving a first alarm signal output by the controller, and performing an alarm operation associated with the first alarm signal to indicate that the PEN protection circuit is disconnected; the first alarm signal is generated and output by the controller after determining that the PEN protection circuit is disconnected.

[0013] Optionally, the controller is also connected to the three-phase live wires of the AC charging pile and the PEN protection wire, and in response to detecting that the resistance between the PEN protection wire and the ground wire is greater than a preset safety resistance threshold, outputs a circuit breaker control signal to disconnect the AC charging pile from the AC power grid.

[0014] Optionally, the first switch is connected to the PEN protection line of the AC charging pile via a PE line.

[0015] Optionally, the disconnection detection system further includes: a self-test circuit, the first end of which is coupled to the second end of the first switch and the second end is grounded; the self-test circuit is also coupled to the controller; the controller is further adapted to detect the grounding status of the casing of the AC charging pile through the self-test circuit.

[0016] Optionally, the self-test circuit includes a second switch and a second resistor, wherein: the first end of the second switch is coupled to the first end of the first resistor, the second end of the second switch is coupled to the first end of the second resistor, and the control end of the second switch is coupled to the controller; the second resistor has its second end grounded.

[0017] Optionally, the disconnection detection system further includes: a second communication device coupled to the controller, receiving a grounding warning signal output by the controller, and forwarding the grounding warning signal to a pre-associated electronic device; the grounding warning signal is generated and output by the controller after determining that the casing of the AC charging pile is not properly grounded.

[0018] Optionally, the disconnection detection system further includes: a second alarm device, coupled to the controller, receiving a second alarm signal output by the controller, and performing an alarm operation associated with the second alarm signal to indicate that the casing of the AC charging pile is not properly grounded; the second alarm signal is generated and output by the controller after determining that the casing of the AC charging pile is not properly grounded.

[0019] In a second aspect of this application, the present invention also provides an AC charging pile, including a disconnection detection system for any of the AC charging piles described above.

[0020] In this embodiment, the PEN protection circuit is determined to be open by comparing the resistance value between the PEN protection line and the ground line with a preset safety resistance threshold. Since the resistance value between the PEN protection line and the ground line is not affected by three-phase imbalance, the accuracy of detecting open circuits in the PEN protection circuit is improved. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of a PEN protection circuit open circuit detection system;

[0022] Figure 2 This is a schematic diagram of the structure of a wire breakage detection system according to an embodiment of the present invention;

[0023] Figure 3 This is a schematic diagram of another wire breakage detection system in an embodiment of this utility model;

[0024] Figure 4 This is a schematic diagram of another wire breakage detection system in this utility model embodiment. Detailed Implementation

[0025] like Figure 1 The diagram shows a schematic of a conventional open circuit detection system for the PEN protection circuit. The open circuit detection system includes a voltage comparison circuit, which is coupled to the three-phase live wires (L1 phase live wire, L2 phase live wire, and L3 phase live wire) and the PEN protection line.

[0026] The voltage comparison circuit constructs a virtual N-phase voltage corresponding to the three-phase live wires using external components (such as resistors or a combination of resistors and capacitors) and compares the virtual N-phase voltage with the voltage on the PEN protection line. When the difference between the virtual N-phase voltage and the voltage on the PEN protection line exceeds a preset voltage threshold, it can be determined that the PEN protection circuit containing the PEN protection line is open.

[0027] However, in practical applications, there are scenarios where the three-phase live wires are unbalanced. In this scenario, using... Figure 1 The provided open circuit detection system has a non-zero vector sum of the L1, L2, and L3 phase live wires, which leads to unstable virtual N-phase voltage and makes it impossible to accurately determine whether the PEN protection circuit is open.

[0028] In this embodiment of the invention, the presence or absence of a PEN protection circuit is determined by comparing the resistance value between the PEN protection line and the ground line with a preset safety resistance threshold. Since the resistance value between the PEN protection line and the ground line is unaffected by three-phase imbalance, the accuracy of detecting a PEN protection circuit break can be improved.

[0029] To make the above-mentioned objectives, features and beneficial effects of this utility model more apparent and understandable, the specific embodiments of this utility model will be described in detail below with reference to the accompanying drawings.

[0030] This utility model provides a wire breakage detection system for AC charging piles (hereinafter referred to as the wire breakage detection system). See reference... Figure 2 A schematic diagram of a wire breakage detection system according to an embodiment of the present invention is provided.

[0031] In this embodiment of the invention, the open circuit detection system may include: a first switch S1, a first resistor RC, a first voltage source U1, a sampling resistor, and a controller. The first switch S1, the first resistor RC, the first voltage source U1, and the sampling resistor are connected in series.

[0032] In specific implementation, the first end of the first switch S1 can be connected to the PEN protection line of the AC charging pile, and the second end of the first switch S1 can be coupled to the first end of the first resistor RC.

[0033] The second end of the first resistor RC can be coupled to the high potential end of the first voltage source U1;

[0034] The low-potential terminal of the first voltage source U1 is coupled to the first terminal of the sampling resistor;

[0035] The second terminal of the sampling resistor is grounded.

[0036] The controller is coupled to the control terminal of the first switch S1 and is used to control the first switch S1 to be turned on during the detection cycle; and when the controller detects that the resistance between the PEN protection line and the ground line is greater than the preset safety resistance threshold, it determines that the PEN protection circuit where the PEN protection line is located is open.

[0037] In practice, during the detection cycle, the first voltage source U1 can periodically output a first voltage and a second voltage, and the first voltage and the second voltage are not equal to the voltage on the PEN protection line.

[0038] In practice, the aforementioned detection cycle can be a period of time during which the AC charging pile is in standby mode. The number of detection cycles can be one, two, or more. The length of the detection cycle can be 1 second, 2 seconds, or other durations.

[0039] In other words, while the charging station is in standby mode, the controller can perform several detection cycles to detect whether the PEN protection circuit is disconnected.

[0040] In practical applications, it is known that when an AC charging pile is in standby mode, it does not output electrical energy to the outside world, that is, the AC charging pile does not have any external charging equipment (such as new energy vehicles).

[0041] In this embodiment of the invention, the controller can also be coupled to the first voltage source U1. During the detection period, the controller can output a voltage control signal to the first voltage source U1. After receiving the voltage control signal, the first voltage source U1 periodically outputs a first voltage and a second voltage at intervals during the detection period.

[0042] During the detection cycle, the first voltage source U1 periodically outputs a first voltage and a second voltage at intervals. This can mean that: during the first half of the detection cycle, the first voltage source U1 outputs the first voltage; and during the second half of the detection cycle, the first voltage source U1 outputs the second voltage. Alternatively, during the first half of the detection cycle, the first voltage source U1 outputs the second voltage; and during the second half of the detection cycle, the first voltage source U1 outputs the first voltage.

[0043] For example, the duration of a detection cycle is 1 second. In the first 0.5 seconds of the detection cycle, the first voltage source U1 outputs a first voltage; in the last 0.5 seconds of the detection cycle, the first voltage source U1 outputs a second voltage.

[0044] In practical implementation, the high-potential terminal of the first voltage source U1 is also the positive terminal of the first voltage source U1; the low-potential terminal of the first voltage source U1 is also the negative terminal of the first voltage source U1. The low-potential terminal of the first voltage source U1 can be connected to signal ground.

[0045] In practice, the first voltage source U1 can be a high-voltage voltage source. The voltage on the PEN protection line can be a three-phase power frequency voltage (380V).

[0046] In some embodiments, the first voltage and the second voltage output by the high-voltage source can both be greater than the three-phase power frequency voltage (380V). For example, the first voltage output by the high-voltage source is 400V, and the second voltage output is 390V.

[0047] In other embodiments, the first voltage and the second voltage output by the high-voltage source can both be less than the three-phase power frequency voltage. For example, the first voltage output by the high-voltage source is 370V, and the second voltage is 360V.

[0048] In some other embodiments, the first voltage output by the high-voltage source can be greater than the three-phase power frequency voltage, and the second voltage can be less than the three-phase power frequency voltage. For example, the first voltage output by the high-voltage source is 390V, and the second voltage is 370V.

[0049] In practical implementation, the open circuit detection system may also include a voltage sampling circuit. The input terminal of the voltage sampling circuit can be coupled to the first terminal of the sampling resistor, and the output terminal of the voltage sampling circuit can be coupled to the controller. The voltage sampling circuit can acquire the voltage at the first terminal of the sampling resistor (also called the sampling voltage) and output the aforementioned first terminal voltage to the controller.

[0050] The voltage at the first terminal of the sampling resistor when the first voltage source U1 outputs the first voltage is different from the voltage at the first terminal of the sampling resistor when the first voltage source U1 outputs the second voltage.

[0051] The following is about the above. Figure 2 The working principle of the provided wire breakage detection system is explained.

[0052] During the detection cycle, the controller outputs a conduction control signal to the control terminal of the first switch S1 and a voltage control signal to the first voltage source U1. Upon receiving the conduction control signal, the first switch S1 conducts, and upon receiving the voltage control signal, the first voltage source U1 periodically outputs a first voltage and a second voltage. The voltage sampling circuit acquires the voltage across the sampling resistor.

[0053] During the detection period, the first voltage source U1, the first resistor RC, the PEN protection line, and the ground wire form a circuit. The first voltage source U1 is connected to the ground wire via the PE line on the AC mains side. When the PEN protection line is normally connected to the ground wire, there is an equivalent resistance RA between the PEN protection line and the ground wire. The equivalent resistance RA is the internal resistance of the PEN protection line between point VA on the PEN protection line and the ground wire.

[0054] When the first voltage source U1 outputs the first voltage V1, the voltage across the first terminal of the sampling resistor is Vr1; when the first voltage source U1 outputs the second voltage V2, the voltage across the first terminal of the sampling resistor is Vr2. In the presence of interference, because the detection period is short, the amplitude of the interference is relatively stable within the detection period; therefore, the change in current flowing through the sampling resistor is only related to the injected voltage.

[0055] The first resistor RC, the sampling resistor, and the equivalent resistance RA are connected in series. Based on Kirchhoff's laws, the following formula can be obtained:

[0056] (1)

[0057] In equation (1), r is the resistance value of the sampling resistor, R A R is the resistance value of the equivalent resistance RA. C This is the resistance value of the first resistor RC.

[0058] In equation (1), Vr1, Vr2, and R C r, V1, and V2 are all known. Therefore, R can be calculated based on the above equation (1). A .

[0059] In practical implementation, R A The specific value can be obtained by calculation using a pre-stored calculation program in the controller. The above formula (1) can be used by those skilled in the art based on... Figure 2 The circuit structure is known, and R is calculated. A The process can also be implemented by writing corresponding calculation programs by those skilled in the art.

[0060] When the PEN protection line is properly connected to the ground line, the resistance value of the equivalent resistance RA is R. A Typically small, usually only tens of ohms or even a few ohms. When the PEN protection wire and ground wire are not properly connected, the equivalent resistance RA will be R. A It can be considered as infinite.

[0061] In this embodiment of the invention, a safety resistance threshold is preset. The controller can adjust the calculated R... A Compare with the safety resistance threshold. When R A When the resistance is less than the safety resistance threshold, it can be determined that the PEN protection line and ground line are normal; when R A When the resistance value exceeds the safety resistance threshold, it can be determined that the PEN protection line is not connected to the ground line, which means that the PEN protection circuit is broken.

[0062] In practice, the safety resistance threshold can be preset. The safety resistance threshold can be set to 1 kiloohm, 100 ohms, or other values.

[0063] In practical implementation, the controller can also be connected to the three-phase live wire and the PEN protection wire. When the controller detects a break in the PEN protection circuit, it can output a circuit breaker control signal to disconnect the AC charging pile from the AC power grid.

[0064] In practical applications, switches can be installed on each of the three-phase live wires (such as L1, L2, and L3) and the PEN protection line of the AC charging pile. For example... Figure 2 As shown, switch K1 is installed on phase L1, switch K2 is installed on phase L2, switch K3 is installed on phase L3, and switch K4 is installed on the PEN protection line.

[0065] In practical implementation, the controller can also be coupled to the control terminals of switches K1, K2, K3, and K4 respectively. When the controller determines that the resistance between the PEN protection line and the ground line is greater than the preset safety resistance threshold, it can output a circuit breaker control signal to the control terminals of switches K1 to K4, switching the state of switches K1 to K4 from the on state to the off state, thereby disconnecting the AC charging pile from the AC power grid.

[0066] When switches K1~K4 are in the open state, there is no voltage output at the output terminals L1-OUT, L2-OUT, L3-OUT, and PEN-OUT of the L1 phase live wire, and PEN-OUT of the PEN protection wire.

[0067] In specific implementation, such as Figure 2 As shown, the low-potential terminal of the first voltage source U1 is coupled to the signal ground, and the first terminal of the sampling resistor is coupled to both the low-potential terminal of the first voltage source U1 and the signal ground. On the signal ground, there may be some noise signals, which can interfere with the voltage at the first terminal of the sampling resistor.

[0068] To avoid interference signals affecting the voltage at the first terminal of the sampling resistor, in this embodiment of the invention, the open circuit detection system may further include a reference voltage source. The low-potential terminal (i.e., the negative terminal) of the reference voltage source is coupled to the low-potential terminal of the first voltage source U1, and the high-potential terminal (i.e., the positive terminal) of the reference voltage source is coupled to the first terminal of the sampling resistor. The reference voltage source can output a constant reference voltage to the first terminal of the sampling resistor.

[0069] By setting a reference voltage source, interference from noise signals on the signal ground on the sampling resistor can be avoided, improving the accuracy of the obtained resistance value of the sampling resistor, and thus improving the accuracy of wire breakage detection.

[0070] Reference Figure 3A schematic diagram of another wire breakage detection system in an embodiment of this utility model is provided. Figure 3 In this circuit, a reference voltage source is provided between the low potential end of the first voltage source U1 and the first end of the sampling resistor.

[0071] In specific implementations, the reference voltage source can be a low-voltage DC voltage source, and its output reference voltage can be preset. In some embodiments, the reference voltage output by the reference voltage source is 3V; in other embodiments, the reference voltage output by the reference voltage source is 5V.

[0072] It is understood that the output voltage of the aforementioned reference voltage source can also be other values, and is not limited to the examples described above.

[0073] In this embodiment of the invention, the first switch S1 can be connected to the PEN protection wire of the AC charging pile via an additional PE wire. The additional PE wire can be installed on the casing of the AC charging pile and coupled to the ground wire.

[0074] Because an additional PE wire is added to the casing of the AC charging station, long-term outdoor use will cause the PE wire to age, which may lead to the casing of the AC charging station failing to be properly grounded, posing a safety hazard.

[0075] To reduce safety hazards, a self-test circuit can be included in the open circuit detection system in this embodiment of the invention. The first terminal of the self-test circuit is coupled to the second terminal of the first switch S1, and the second terminal of the self-test circuit is open. The self-test circuit can also be coupled to the controller. The controller can also detect the grounding status of the AC charging pile's casing through the self-test circuit. The grounding status of the AC charging pile's casing can include normal grounding and abnormal grounding (i.e., no normal grounding).

[0076] Reference Figure 4 A schematic diagram of another wire breakage detection system according to an embodiment of the present invention is provided. In a specific implementation, the self-test circuit may include a second switch S2 and a second resistor RB, wherein:

[0077] The first end of the second switch S2 is coupled to the first end of the first resistor RC and the second end of the first switch S1. The second end of the second switch S2 is coupled to the first end of the second resistor RB. The second end of the second resistor RB is grounded.

[0078] In practical implementation, the control terminal of the second switch S2 can be coupled to the controller (for simplicity of the attached diagram, ...). Figure 4 (Not shown in the diagram). The controller can output a control signal to the control terminal of the second switch S2 to control the second switch S2 to be turned on or off.

[0079] The working principle and process of the self-test circuit are explained below.

[0080] The controller can activate the self-test circuit during the self-test period to check whether the AC charging pile's casing is properly grounded. This self-test period can be a time interval during which the AC charging pile is in standby mode. The self-test period and the aforementioned detection cycle do not overlap in the time domain.

[0081] In other words, the controller can check whether the charging pile's outer casing is properly grounded before checking whether the PEN protection wire is broken. Alternatively, the controller can check whether the charging pile's outer casing is properly grounded after checking whether the PEN protection wire is broken.

[0082] During the self-test period, the controller controls the first switch S1 to open and the second switch S2 to open. Combined with... Figure 4 As can be seen from the disconnection detection system provided, the first voltage source U1, the first resistor RC, and the second resistor RB form a circuit. The first voltage source U1 outputs the first voltage V1 and the second voltage V2 intermittently during the self-detection period.

[0083] The controller can acquire the voltage change across the sampling resistor and calculate the impedance R between point VB and ground based on the following formula. VB :

[0084] (2)

[0085] If the calculated impedance value R VB If there is a deviation from the actual resistance value of the second resistor RB, and the deviation exceeds the preset resistance deviation threshold, it can be determined that the casing of the AC charging pile is not properly grounded (i.e., there is a grounding abnormality); if the deviation does not exceed the preset resistance deviation threshold, it can be determined that the casing of the AC charging pile is properly grounded.

[0086] In practical implementation, the aforementioned resistance deviation threshold can be the actual resistance value R associated with the second resistor RB. B In some embodiments, the aforementioned resistance deviation threshold can be the actual resistance value R of the second resistor RB. B 10%. When |R VB -R B |>R B When the value is ×10%, it can be determined that the casing of the AC charging pile is not properly grounded.

[0087] In practical implementation, the open circuit detection system may also include a first alarm device coupled to the controller. After determining that the PEN protection circuit is open, the controller generates a first alarm signal and outputs the first alarm signal to the first alarm device. Upon receiving the first alarm signal, the first alarm device can output an alarm operation associated with the first alarm signal.

[0088] In some embodiments, the first alarm device may include a speaker. Upon receiving a first alarm signal, the first alarm device may play a pre-set voice message.

[0089] For example, the controller generates a first alarm signal after determining that the PEN protection circuit is disconnected. Upon receiving the first alarm signal, the first alarm device plays the voice message "PEN protection line is disconnected, charging pile is out of service" repeatedly.

[0090] In other embodiments, the first alarm device may include an LED display screen. After receiving a first alarm signal, the first alarm device displays pre-set text on the LED display screen.

[0091] For example, the controller generates a first alarm signal after determining that the PEN protection circuit is disconnected. Upon receiving the first alarm signal, the first alarm device displays the message "PEN protection line is disconnected, charging station temporarily out of service" on the LED display screen.

[0092] In some other embodiments, the first alarm device may also include a speaker and an LED display screen, which will prompt the user that the PEN protection line has been disconnected and the AC charging pile cannot be used normally for the time being through "voice plus display".

[0093] In practical implementation, the disconnection detection system may also include a second alarm device coupled to the controller. After determining that the casing of the AC charging pile is not properly grounded, the controller generates a second alarm signal and outputs the second alarm signal to the alarm device. Upon receiving the second alarm signal, the second alarm device can output an alarm operation associated with the second alarm signal.

[0094] In some embodiments, the second alarm device may include a speaker. Upon receiving a second alarm signal, the second alarm device may play a pre-set voice message.

[0095] For example, the controller generates a second alarm signal after determining that the casing of the AC charging pile is not properly grounded. Upon receiving the second alarm signal, the second alarm device plays the voice message "The casing of the AC charging pile is not properly grounded" repeatedly.

[0096] In other embodiments, the second alarm device may include an LED display screen. After receiving a second alarm signal, the second alarm device displays pre-set text on the LED display screen.

[0097] For example, the controller generates a second alarm signal after determining that the casing of the AC charging pile is not properly grounded. Upon receiving the second alarm signal, the second alarm device displays the message "The casing of the AC charging pile is not properly grounded" on the LED display screen.

[0098] In some other embodiments, the second alarm device may also include both a speaker and an LED display screen, prompting the user that the casing of the AC charging pile is not properly grounded through a "voice plus display" method.

[0099] In practice, the first alarm device and the second alarm device mentioned above can be the same alarm device to provide an alarm for a broken PEN protection circuit and an alarm for a non-grounded casing of the AC charging pile.

[0100] In practical implementation, the disconnection detection system may further include a first communication device coupled to the controller. After determining that the PEN protection circuit is disconnected, the controller generates a disconnection warning signal and outputs it to the first communication device. Upon receiving the disconnection warning signal, the first communication device can forward it to a pre-associated electronic device. This pre-associated electronic device may be a smartphone of the charging station operator's staff or the charging station operator's server, etc.

[0101] When the controller outputs a disconnection warning signal, it can also add identification information of the AC charging pile where the PEN protection circuit has been disconnected. This allows for timely notification to the AC charging pile operator regarding any instances of PEN protection circuit disconnection.

[0102] It is understood that the aforementioned speakers, LED displays, etc., are merely illustrative examples of alarm devices. Alarm devices can also be other types of devices that can alert users, which will not be listed here.

[0103] In practice, the first communication device can communicate with the controller via a wired connection or via wireless communication.

[0104] In practical implementation, the first communication device can communicate with a pre-associated electronic device through a wireless communication module. The wireless communication module can be any of the following: a Wi-Fi communication module, a cellular network communication module (such as a 4G communication module, a 5G communication module, etc.), or a Bluetooth communication module.

[0105] In practical implementation, the disconnection detection system may also include a second communication device coupled to the controller. After determining that the AC charging pile's casing is not properly grounded, the controller generates a grounding warning signal and outputs it to the second communication device. Upon receiving the grounding warning signal, the second communication device can forward it to a pre-associated electronic device.

[0106] When the controller outputs a grounding warning signal, it can also add the AC charging pile's identification information to the signal. This allows for timely alerts to operators regarding AC charging piles whose casings are not properly grounded.

[0107] In practice, the second communication device can communicate with the controller via a wired connection or via wireless communication.

[0108] In practice, the second communication device can communicate with a pre-associated electronic device via a wireless communication module. The wireless communication module can be any of the following: a Wi-Fi communication module, a cellular network communication module (such as a 4G communication module, a 5G communication module, etc.), or a Bluetooth communication module.

[0109] The first communication device and the second communication device mentioned above can be the same communication device or two independent communication devices.

[0110] In practical implementation, the disconnection detection system may also include a DC power supply to power the controller, alarm devices, communication devices, voltage sampling circuits, etc. The output voltage of the DC power supply can be 5V, 12V, or other voltage values.

[0111] In summary, the open circuit detection system provided by this utility model determines whether the PEN protection line is open by comparing the resistance value between the PEN protection line and the ground line with a preset safety resistance threshold. Since the resistance value between the PEN protection line and the ground line is not affected by three-phase imbalance, it can improve the accuracy of open circuit detection in the PEN protection circuit.

[0112] This utility model embodiment also provides an AC charging pile, including the wire breakage detection system provided in any of the above embodiments.

[0113] While the present invention has been disclosed above, it is not limited thereto. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the present invention; therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A wire breakage detection system for an AC charging pile, characterized in that, include: A first switch, a first resistor, a first voltage source, a sampling resistor, and a controller are connected in series, wherein: The first switch has its first end connected to the PEN protection line of the AC charging pile, and its second end coupled to the first end of the first resistor. The second end of the first resistor is coupled to the high-potential end of the first voltage source. The first voltage source has its low-potential terminal coupled to the first terminal of the sampling resistor; The second terminal of the sampling resistor is grounded; The controller is coupled to the control terminal of the first switch and is used to control the first switch to conduct during the detection period; and to determine that the PEN protection circuit is open when the resistance between the PEN protection line and the ground line is detected to be greater than a preset safety resistance threshold. During the detection period, the first voltage source periodically outputs a first voltage and a second voltage at intervals, and the first voltage, the second voltage, and the voltage on the PEN protection line are all unequal.

2. The wire breakage detection system as described in claim 1, characterized in that, Also includes: A voltage sampling circuit, whose input terminal is coupled to the first terminal of the sampling resistor and whose output terminal is coupled to the controller, is used to acquire the voltage at the first terminal of the sampling resistor and output it to the controller.

3. The wire breakage detection system as described in claim 1, characterized in that, Also includes: A reference voltage source has its low-potential terminal coupled to the low-potential terminal of the first voltage source, and its high-potential terminal coupled to the first terminal of the sampling resistor, outputting a constant reference voltage to the first terminal of the sampling resistor.

4. The wire breakage detection system as described in claim 1, characterized in that, Also includes: A first communication device, coupled to the controller, is used to receive a disconnection warning signal output by the controller and forward the disconnection warning signal to a pre-associated electronic device.

5. The wire breakage detection system as described in claim 1, characterized in that, Also includes: The first alarm device is coupled to the controller, receives the first alarm signal output by the controller, and performs an alarm operation associated with the first alarm signal to indicate that the PEN protection circuit is disconnected; the first alarm signal is generated and output by the controller after determining that the PEN protection circuit is disconnected.

6. The wire breakage detection system as described in claim 1, characterized in that, The controller is also connected to the three-phase live wires of the AC charging pile and the PEN protection wire. In response to detecting that the resistance between the PEN protection wire and the ground wire is greater than a preset safety resistance threshold, the controller outputs a circuit breaker control signal to disconnect the AC charging pile from the AC power grid.

7. The wire breakage detection system as described in claim 1, characterized in that, Also includes: The self-test circuit has a first terminal coupled to the second terminal of the first switch, and the second terminal is grounded; the self-test circuit is also coupled to the controller. The controller is also adapted to detect the grounding status of the casing of the AC charging pile through the self-test circuit.

8. The wire breakage detection system as described in claim 7, characterized in that, The self-test circuit includes a second switch and a second resistor, wherein: The second switch has a first terminal coupled to the first terminal of the first resistor, a second terminal coupled to the first terminal of the second resistor, and a control terminal coupled to the controller. The second resistor has its second terminal grounded.

9. The wire breakage detection system as described in claim 1, characterized in that, Also includes: The second communication device is coupled to the controller, receives the grounding indication signal output by the controller, and forwards the grounding indication signal to the pre-associated electronic device; The grounding warning signal is generated and output by the controller after determining that the casing of the AC charging pile is not properly grounded.

10. An AC charging pile, characterized in that, include: The open circuit detection system for AC charging piles as described in any one of claims 1 to 9.

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