Charging pile fault detection circuit and charging gun

Abstract

The present application relates to a charging pile fault detection circuit and a charging gun. In the charging pile fault detection circuit, an input end of a first switch is connected to an input end of the charging gun, an input end of an equivalent analog resistor is connected to an output end of the first switch, and an output end of the equivalent analog resistor is connected to an output end of the charging gun; an on-off state of the second switch is different from an on-off state of the first switch; a preset resistor and the second switch are connected in series between the input end of the charging gun and the equivalent analog resistor; and a sampling circuit is configured to sample an electrical signal applied to the equivalent analog resistor, wherein the electrical signal represents a fault condition of the charging pile. Thus, accurate fault detection of the charging pile is realized.

Description

Charging pile fault detection circuit and charging gun

[0001] This application claims priority to Chinese Patent Application No. 202411206678.5, filed on August 29, 2024, entitled "Charging Pile Fault Detection Circuit and Charging Gun", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of charging pile charging detection technology, and in particular to a charging pile fault detection circuit and a charging gun. Background Technology

[0003] With the increasing popularity of electric vehicles, people are paying more and more attention to the charging safety of electric vehicles. Current charging pile output ports are prone to short circuits and open circuits, causing accidents such as fires and explosions. Therefore, there is an urgent need to provide output fault detection for charging piles. The applicant has found that traditional fault detection solutions can misdiagnose faults when the charging pile is operating normally. Summary of the Invention

[0004] Therefore, it is necessary to provide a charging pile fault detection circuit and a charging gun that can accurately detect the fault conditions of charging piles.

[0005] Firstly, a charging pile fault detection circuit is provided, the charging pile fault detection circuit comprising:

[0006] The first switch, the input terminal of the first switch is connected to the input terminal of the charging gun;

[0007] The equivalent analog resistor has its input terminal connected to the output terminal of the first switch, and its output terminal connected to the output terminal of the charging gun.

[0008] The second switch has a different on / off state than the first switch;

[0009] A preset resistor is connected in series with the second switch between the input terminal of the charging gun and the equivalent analog resistor.

[0010] The sampling circuit is used to sample the electrical signal applied to the equivalent analog resistor, and the electrical signal is used to characterize the fault condition of the charging pile.

[0011] In one embodiment, the sampling circuit includes at least one of the following circuits:

[0012] Current sampling circuit, used to detect the current flowing through the equivalent analog resistance;

[0013] The voltage sampling circuit is used to sample the voltage applied to the output terminal of the charging gun.

[0014] In one embodiment, the current sampling circuit includes:

[0015] A current transformer is used to detect the current flowing through an equivalent analog resistance.

[0016] In one embodiment, the coil of the current transformer is coupled to the series branch containing the second switch and the preset resistor.

[0017] In one embodiment, the voltage sampling circuit includes:

[0018] Voltage divider resistor unit;

[0019] The sampling resistor and the voltage divider resistor unit are connected in series and then in parallel across the equivalent analog resistor, and the resistance value of the sampling resistor is less than the resistance value of the voltage divider resistor unit.

[0020] In one embodiment, the preset resistor is a fixed current-limiting resistor or a positive temperature coefficient resistor.

[0021] In one embodiment, the charging pile fault detection circuit further includes:

[0022] The controller is connected to the first switch, the second switch, and the sampling circuit. The controller is used to control the second switch to close and the first switch to open, and to determine the fault status of the charging pile based on the electrical signal.

[0023] In one embodiment, when a current sampling circuit is included, the controller is connected to the current sampling circuit, wherein the controller is configured to determine that the charging pile output is open-circuited when the current is detected to be 0; or, the controller is configured to determine that the charging pile output is short-circuited when the current is equal to the ratio of the voltage provided by the charging pile to a preset resistance, or when the difference between the current and a reference current is greater than or equal to a current difference threshold; or, the controller is configured to determine that the output impedance of the charging pile does not meet the charging safety requirements when the resistance difference between the target resistance value and the preset resistance is less than or equal to a short-circuit impedance safety threshold, wherein the target resistance value is determined by the current and the voltage provided by the charging pile.

[0024] In one embodiment, when a voltage sampling circuit is included, the controller is connected to the voltage sampling circuit, wherein the controller is configured to determine that the charging pile output is short-circuited when the charging pile provides voltage and the voltage at the output terminal of the charging gun is 0; or, to determine that the charging pile output is open-circuited when the voltage at the output terminal of the charging gun is equal to the voltage provided by the charging pile.

[0025] In one embodiment, the controller is connected to the charging pile, and the controller is also used to control the charging pile to stop outputting voltage in the event that a fault is determined to be in the charging pile.

[0026] In one embodiment, the charging pile fault detection circuit further includes:

[0027] The alarm module is used to output alarm information in the event of a charging pile malfunction.

[0028] Secondly, a charging gun is provided, including the aforementioned charging pile fault detection circuit.

[0029] The aforementioned charging pile fault detection circuit and charging gun include a first switch and a second switch connected in parallel. When the second switch is closed and the first switch is open, a fault test condition is entered. Under this fault test condition, the sampling circuit collects the electrical signal actually applied to the equivalent analog resistance (the impedance between the positive and negative terminals of the charging gun). This electrical signal can characterize the electrical signal actually applied from the output terminal of the charging pile to the output terminal of the charging gun. When the charging pile malfunctions, the electrical signal actually applied to the output terminal of the charging gun differs from the electrical signal when the charging pile is not malfunctioning. Therefore, the electrical signal collected by the sampling circuit can characterize the fault condition of the charging pile. In addition, under the charging pile fault detection circuit architecture provided in this application embodiment, when testing, the second switch is closed and the first switch is open. The electrical signal collected by the sampling circuit is not affected by the resistive devices on the charging path from the charging pile through the first switch to the charging gun under non-test conditions, ensuring the accuracy and effectiveness of the electrical signal sampling, thereby achieving accurate detection of charging pile fault conditions. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of this application or the conventional technology, the drawings used in the description of the embodiments or the conventional technology will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 is a structural block diagram of a charging pile fault detection circuit according to one embodiment;

[0032] Figure 2 is a second structural block diagram of a charging pile fault detection circuit according to an embodiment;

[0033] Figure 3 is a third structural block diagram of a charging pile fault detection circuit according to an embodiment;

[0034] Figure 4 is a structural block diagram of a charging pile fault detection circuit according to an embodiment;

[0035] Figure 5 is a structural block diagram of a charging pile fault detection circuit according to an embodiment;

[0036] Figure 6 is a structural block diagram of a charging pile fault detection circuit according to an embodiment;

[0037] Figure 7 is a structural block diagram of a charging pile fault detection circuit according to an embodiment;

[0038] Figure 8 is a structural block diagram of a charging pile fault detection circuit according to an embodiment;

[0039] Figure 9 is a structural block diagram of a charging pile fault detection circuit according to an embodiment;

[0040] Figure 10 is a structural block diagram of a charging pile fault detection circuit according to an embodiment;

[0041] Figure 11 is an eleventh structural block diagram of a charging pile fault detection circuit according to an embodiment;

[0042] Figure 12 is a structural block diagram of a charging pile fault detection circuit according to an embodiment;

[0043] Figure 13 is a block diagram of a charging pile fault detection circuit according to an embodiment.

[0044] Figure 14 is a block diagram of a charging pile fault detection circuit according to one embodiment. Detailed Implementation

[0045] To facilitate understanding of this application, a more complete description will be provided below with reference to the accompanying drawings, which illustrate embodiments of the present application. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that the disclosure of this application will be thorough and complete.

[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 herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0047] It is understood that the terms "first," "second," etc., used in this application may be used herein to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish one element from another. For example, without departing from the scope of this application, a first switch may be referred to as a second switch, and similarly, a second switch may be referred to as a first switch. Both the first switch and the second switch are switches, but they are not the same switch.

[0048] It is understood that the term "connection" in the following embodiments should be understood as "electrical connection," "communication connection," etc., if the connected circuits, modules, units, etc., have electrical signal or data transmission with each other.

[0049] When used herein, the singular forms of “a,” “an,” and “the” may also include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms “comprising / including” or “having,” etc., specify the presence of the stated features, wholes, steps, operations, components, parts, or combinations thereof, but do not preclude the possibility of the presence or addition of one or more other features, wholes, steps, operations, components, parts, or combinations thereof. Meanwhile, the term “and / or” as used in this specification includes any and all combinations of the associated listed items.

[0050] In one embodiment, as shown in FIG1, a charging pile fault detection circuit is provided, which includes: a first switch 10, an equivalent analog resistor 20, a second switch 30, a preset resistor 40, and a sampling circuit 50.

[0051] As shown in Figure 1, the input terminal of the first switch 10 is connected to the input terminal of the charging gun (Input), the input terminal of the equivalent analog resistor 20 is connected to the output terminal of the first switch 10, and the output terminal of the equivalent analog resistor 20 is connected to the output terminal of the charging gun (Output). A preset resistor 40 and a second switch 30 are connected in series between the input terminal of the charging gun (Input) and the equivalent analog resistor 20. A sampling circuit 50 is used to sample the electrical signal applied to the equivalent analog resistor 20. The second switch 30 has a different on / off state than the first switch 10. When charging pile fault detection is required, the first switch 10 is open and the second switch 30 is closed; when charging pile fault detection is not required, the first switch 10 can remain closed and the second switch 30 open. The electrical signal applied to the equivalent analog resistor 20 may include at least one of current and voltage.

[0052] Specifically, when a charging pile fault test is required, as shown in Figure 1, the second switch 30 is in the closed state and the first switch 10 is in the open state. At this time, the current output by the charging pile flows into the input terminal of the charging gun, and is transmitted to the output terminal of the charging gun through the second switch 30, the preset resistor 40, and the equivalent analog resistor 20. The electrical signal of the equivalent analog resistor 20 (the equivalent analog resistance on the charging path between the input terminal of the charging gun and the output terminal of the charging gun) collected by the sampling circuit 50 can characterize the electrical signal actually loaded from the output terminal of the charging pile to the output terminal of the charging gun. When a short circuit or open circuit occurs at the output of the charging pile (i.e., a short circuit or open circuit occurs in the electrical signal transmission path between the output terminal of the charging pile and the output terminal of the charging gun), the electrical signal actually loaded to the output terminal of the charging gun differs from the electrical signal loaded to the output when the charging pile output is not faulty. Based on this difference, the fault condition of the charging pile can be determined. Therefore, the fault condition of the charging pile can be determined based on this electrical signal.

[0053] The charging pile fault detection circuit provided in this application embodiment employs a first switch and a second switch to achieve a switchable design for two branches. When detecting charging pile output faults, the first switch is opened and the second switch is closed, selecting the branch connected in series with a preset resistor and an equivalent analog resistor. The sampling circuit samples the electrical signal applied to the equivalent analog resistor at this time. This electrical signal characterizes the charging pile fault condition, thus achieving charging pile fault detection. The sampling accuracy of this charging pile fault detection circuit is unaffected by the components along the charging path from the charging gun input to the charging gun output under charging conditions (when the first switch is on), ensuring that the electrical signal accurately reflects the actual electrical signal applied to the charging gun output, thereby achieving precise detection of charging pile faults.

[0054] In one embodiment, as shown in Figures 2-4, the sampling circuit 50 includes at least one of the following circuits: a current sampling circuit 51 and a voltage sampling circuit 52.

[0055] The current sampling circuit is used to detect the current flowing through the equivalent analog resistance. The voltage sampling circuit is used to sample the voltage applied to the output terminal of the charging gun.

[0056] The form of the current sampling circuit is not limited here. For example, the implementation of the current sampling circuit can include, but is not limited to, current sensor measurement methods such as current transformers and Hall current sensors, as well as sampling resistor measurement methods. Optionally, a sampling resistor (with a known resistance value) can be connected in series in the line containing the equivalent analog resistor, and the current magnitude can be calculated by measuring the voltage difference across the sampling resistor. Optionally, the primary coil of a current transformer can be connected to the line containing the equivalent analog resistor. Based on the principle of electromagnetic induction, the current transformer converts the current in the line containing the equivalent analog resistor into a secondary current for output. Since the number of turns of the coil is fixed, the relationship between the secondary current and the current of the equivalent analog resistor is fixed. Based on this determined relationship, the current of the equivalent analog resistor can be measured. Other implementation methods of the current sampling circuit are not exhaustively listed here.

[0057] Voltage sampling circuits can take many forms. For example, they can be implemented as isolated sampling circuits or non-isolated sampling circuits.

[0058] For isolated sampling circuits, voltage sampling circuits may include, but are not limited to, voltage transformers, optocoupler sampling circuits, and Hall effect sampling circuits.

[0059] In one optional embodiment, the voltage sampling circuit includes a voltage transformer. The two ends of the equivalent analog resistor are connected to the primary side terminals of the voltage transformer, so that the measured voltage result is output through the secondary side of the voltage transformer. The measured voltage result has a defined mapping relationship with the voltage of the equivalent analog resistor. Based on this mapping relationship, the voltage of the equivalent analog resistor can be determined, thereby realizing voltage sampling of the equivalent analog resistor.

[0060] In one optional embodiment, the voltage sampling circuit includes a linear optocoupler. The input terminal of the linear optocoupler is connected to both ends of an equivalent analog resistor. Driven by the voltage of the equivalent analog resistor, the light-emitting diode inside the linear optocoupler generates a light signal with an intensity matching the voltage. The photodiode inside the linear optocoupler receives the light signal emitted by the light-emitting diode and converts it into a photocurrent. This photocurrent is then converted into a voltage signal by a conversion circuit and output. The mapping relationship between this voltage signal and the equivalent analog resistor is determined, thereby enabling voltage measurement of the equivalent analog resistor.

[0061] Hall effect sampling circuits and other isolated sampling circuits that implement voltage sampling will not be listed exhaustively here.

[0062] For non-isolated sampling circuits, voltage sampling circuits may include, but are not limited to, voltage divider sampling circuits and operational amplifier direct sampling circuits.

[0063] Optionally, the voltage divider sampling circuit is connected in parallel with the equivalent analog resistor, and the voltage divider sampling circuit includes resistors with different resistance values. The resistor with the smallest resistance value is used as the sampling circuit. In this case, the voltage applied to the voltage divider sampling circuit is the same as the voltage of the equivalent analog resistor. By further sampling through the sampling circuit with the smallest resistance value, the large voltage across the equivalent analog resistor can be reduced to a small voltage before output, which is convenient for reading by controllers such as MCUs (Microcontroller Units).

[0064] In one embodiment, as shown in Figures 5-6, the current sampling circuit 51 includes a current transformer CT. The current transformer CT is used to detect the current flowing through the equivalent analog resistance 20.

[0065] A current transformer consists of a closed iron core and a coil. The coil is wound on the branch where the equivalent analog resistance is located to measure the current of the equivalent analog resistance.

[0066] The core of the current transformer is made of ferromagnetic material, such as iron or sodium, and is typically toroidal or rectangular in shape with good magnetic permeability. The windings can be made of thin wire and wound around the core. Optionally, the secondary winding of the current transformer has more turns than the primary winding, and the secondary wires are thinner than the primary wires. The current transformer amplifies the current flowing through an equivalent analog resistance, improving test sensitivity and thus enhancing the overall sensitivity of the charging pile fault detection circuit. The secondary side of the current transformer can form a closed circuit with instruments with low impedance (such as the current coils of ammeters and wattmeters) or controllers to send the measurement results to the instruments or controllers.

[0067] In one implementation, the wires of the branch containing the equivalent analog resistance are inserted into the loops of the current transformer (the more turns the current is, the more turns are needed), and the instrument or controller is connected to the two terminals of the secondary side of the current transformer. According to Ampere's law, the generated magnetic field passes through the iron core, causing a change in the magnetic flux within it. This changing magnetic flux induces an electromotive force in the secondary winding of the current transformer, thereby generating a secondary current (i.e., the current measured by the current transformer). The actual current of the equivalent analog resistance is obtained by multiplying the current measured by the current transformer's turns ratio and then dividing the result by the number of turns of the wire inserted into the current transformer.

[0068] In one implementation, the current transformer employs a voltage output method to ensure the stability and reliability of the output signal during transmission. Specifically, the induced electromotive force (EMF) of the secondary winding of the current transformer can be used as the output signal, and the magnitude of the induced EMF is proportional to the magnitude of the current in the branch containing the equivalent analog resistance. Since the induced EMF is usually very small and cannot be directly measured, a signal processing circuit can also be provided. The signal processing circuit is connected to the secondary winding of the current transformer, and amplifies the induced EMF of the secondary winding before outputting it.

[0069] Optionally, the current transformer may also include a filter circuit, which is used to filter the signal after it has been amplified by the signal processing circuit to remove high-frequency noise and spurious signals, retain the low-frequency part, and improve the sampling accuracy.

[0070] In an optional embodiment, the current transformer may further include a linearization processing circuit. The input of this linearization processing circuit is connected to the output of the filter circuit, and linearly correlates the output signal of the filter circuit with the current in the branch containing the equivalent analog resistor to eliminate nonlinear errors, thereby improving the current sampling accuracy of the equivalent analog resistor.

[0071] In one embodiment, as shown in Figures 5-6, the coil of the current transformer CT is coupled to the series branch containing the second switch 30 and the preset resistor 40.

[0072] Specifically, as shown in Figures 5 and 6, the branch containing the second switch 30 and the preset resistor 40 is connected in parallel with the branch containing the first switch 10. When the current transformer is set in the branch containing the preset resistor 40, when the first switch 10 is closed and the second switch 30 is open, no current flows through the branch containing the preset resistor 40, and the current transformer CT has no output. When the first switch 10 is open and the second switch 30 is closed, the current connected to the input terminal of the charging gun is transmitted to the output terminal of the charging gun through the second switch 30, the preset resistor 40, and the equivalent analog resistor 20 in sequence. Therefore, the current measured by the current transformer CT is the current flowing through the equivalent analog resistor 20, thus realizing the current measurement of the equivalent analog resistor 20. Based on this, it can be seen that by coupling the coil of the current transformer CT with the series branch containing the second switch 30 and the preset resistor 40, it can be ensured that the current data measured by the current transformer CT is the current flowing through the equivalent analog resistor 20 when the second switch 30 is closed (i.e., the fault detection condition), without the need to filter out the current data flowing through the equivalent analog resistor 20 when the first switch 10 is closed, thus improving the fault detection efficiency of the charging pile.

[0073] In one embodiment, as shown in Figures 7-8, the voltage sampling circuit 52 includes a voltage divider resistor unit 521 and a sampling resistor 522. The sampling resistor 522 and the voltage divider resistor unit 521 are connected in series and then in parallel across the equivalent analog resistor 20, and the resistance value of the sampling resistor 522 is less than the resistance value of the voltage divider resistor unit 521.

[0074] The sampling resistor and the voltage divider resistor are connected in series and then in parallel with the equivalent analog resistor. Therefore, the total voltage across the sampling resistor and the voltage divider resistor is equal to the voltage across the equivalent analog resistor. Furthermore, since the voltage divider resistor and the sampling resistor are connected in series, the current flowing through them is the same. According to Ohm's law, when the total resistance of the voltage divider resistor and the sampling resistor is constant, the greater the current flowing through them, the greater the total voltage across them. Therefore, the voltage across the sampling resistor is directly proportional to the voltage across the equivalent analog resistor. Thus, by measuring the voltage across the sampling resistor, the voltage across the equivalent analog resistor can be calculated.

[0075] According to the principle of series voltage division, the larger the resistance, the larger the voltage divided; the smaller the resistance, the smaller the voltage divided. Therefore, when the resistance of the voltage divider resistor unit is greater than the resistance of the sampling resistor, the voltage divided by the sampling resistor is less than the voltage divided by the voltage divider resistor unit. When the current flowing through the voltage sampling circuit is large, the voltage across the sampling resistor remains at a low level, preventing abnormal situations such as circuit failures in the back-end connection caused by excessive sampling voltage, and improving the reliability and stability of the charging pile fault detection circuit.

[0076] In addition, since the resistance of the voltage divider resistor unit is relatively large, it can limit the current in the series branch where the voltage divider resistor unit and the sampling resistor are located, preventing the current in the branch where the sampling resistor is located from being too large, thus playing a current limiting protection role.

[0077] Furthermore, voltage sampling based on a sampling resistor (e.g., resistor R2 in Figures 7-8) enables non-destructive sampling of the signal, without affecting the waveform and amplitude of the original signal. At the same time, the signal can be taken out to other circuits for processing or analysis, improving the system's flexibility and adjustability.

[0078] In one embodiment, the sum of the resistance values ​​of the voltage divider resistor unit and the sampling resistor can be a large value in the kiloohm or gigaohm range, much larger than the resistance value of the equivalent analog resistor. This ensures that under fault testing conditions, the total resistance value of the voltage sampling circuit connected in parallel with the equivalent analog resistor is close to the resistance value of the equivalent analog resistor. This minimizes the impact on the magnitude of the voltage applied to the equivalent analog resistor, thereby ensuring that the collected voltage accurately reflects the voltage magnitude at the charging pile output terminal and improving detection accuracy.

[0079] In one embodiment, the voltage divider resistor unit may include multiple resistors connected in series (e.g., resistors R1 and R3 shown in Figures 7-8). With multiple resistors connected in series, the total resistance value of the voltage divider resistor unit can be flexibly adjusted, providing greater design freedom and allowing the resistance value to be more accurately matched to the circuit parameters required by the charging pile fault detection circuit.

[0080] In addition, each resistor in the voltage divider resistor unit shares a portion of the power loss and generates corresponding heat. Because the heat is distributed across multiple resistors, the temperature rise of each resistor is relatively low, which helps improve the heat dissipation performance of the voltage sampling circuit, prevents the resistors from being damaged by overheating, and thus improves the reliability and service life of the charging pile fault detection circuit.

[0081] Furthermore, when the voltage divider resistor unit includes multiple resistors connected in series, even if some of the resistors experience a short circuit, the other resistors can still provide a certain resistance value, preventing the circuit from completely failing. This fault tolerance improves the reliability and stability of the charging pile fault detection circuit. Using multiple resistors connected in series reduces the voltage withstand capability requirements of individual resistors, allowing for the selection of lower-cost resistor devices and thus lowering the cost of the charging pile fault detection circuit.

[0082] In one embodiment, as shown in Figures 9-10, the sampling circuit may simultaneously include a current sampling circuit and a voltage sampling circuit. The explanations of the current and voltage sampling circuits can be found in the descriptions of the above embodiments and will not be repeated here. The charging pile fault detection circuit provided in this application, by sampling voltage and current data, can, on the one hand, comprehensively judge the fault condition of the charging pile based on two types of signals, improving detection accuracy. For example, only when the voltage sampled by the voltage sampling circuit indicates a short circuit at the charging pile output, and the current sampled by the current sampling circuit also indicates a short circuit at the charging pile output, is it considered that a short circuit fault has indeed occurred at the charging pile output, avoiding misjudgments caused by faults in either the voltage or current sampling circuit. On the other hand, even if one of the voltage or current sampling circuits is damaged, it can still ensure that at least one voltage or current sampling result is available to characterize the charging pile fault condition, improving the operational reliability of the charging pile fault detection circuit.

[0083] In one embodiment, the preset resistor is a fixed current-limiting resistor. By using a customized current-limiting resistor, when the charging pile output is short-circuited or open-circuited, the large current can be prevented from burning out the components in the circuit, thus achieving overcurrent protection, improving charging safety and reliability, and also extending the service life of the equipment.

[0084] The selection of the preset resistor can be determined based on considerations such as cost and size in the actual application scenario. For example, in one optional approach, a cement resistor can be used as the preset resistor. Cement resistors are low in cost, thereby reducing the overall cost of the charging pile fault detection circuit.

[0085] Optionally, the preset resistor can be a resistor with good thermal conductivity. When the charging pile output is short-circuited, the preset resistor can dissipate heat in time, avoid damage to local components caused by heat accumulation, and thus improve circuit reliability.

[0086] In one embodiment, the preset resistor is a positive temperature coefficient resistor. The resistance of a positive temperature coefficient resistor increases with increasing temperature.

[0087] Under fault testing conditions, the preset resistor and the equivalent analog resistor are connected in series. In a series circuit, the current is the same everywhere, and the preset resistor and the equivalent analog resistor share the voltage in their respective series branches. When a short circuit occurs at the charging pile output, the equivalent analog resistor is short-circuited. The equivalent resistance of the series branch containing the preset resistor and the equivalent analog resistor becomes equal to the value of the preset resistor, i.e., the resistance decreases. According to Ohm's law I = U / R (where I is the current, U is the voltage, and R is the resistance), with a constant voltage U, a decrease in resistance R leads to an increase in current I. As the current increases, the voltage drop across the positive temperature coefficient resistor also increases, resulting in increased heat generation and a rise in the temperature of the preset resistor. Since the resistance of a positive temperature coefficient resistor increases with increasing temperature, according to Ohm's law, with a constant voltage, an increase in resistance leads to a decrease in current. Therefore, the preset resistor automatically increases its resistance value when the current increases, thus limiting the further increase in current flowing through it, thereby improving the overall circuit reliability.

[0088] In one embodiment, the preset resistor can be a PTC (Positive Temperature Coefficient) thermistor. PTC thermistors are small in size, which helps reduce the size of the charging pile fault detection circuit while achieving overcurrent protection.

[0089] In one embodiment, as shown in FIG11, the charging pile fault detection circuit further includes a controller 60.

[0090] The controller 60 is connected to the first switch 10, the second switch 30 and the sampling circuit 50 respectively. The controller 60 is used to control the second switch 30 to close and the first switch 10 to open, and to determine the fault status of the charging pile based on the electrical signal.

[0091] Specifically, when charging pile fault detection is required, as shown in Figure 11, the controller 60 controls the second switch 30 to close and the first switch 10 to open. The current output by the charging pile is transmitted to the output terminal (Output) of the charging gun via the second switch 30, the preset resistor 40, and the equivalent analog resistor 20. The sampling circuit 50 collects the electrical signal applied to the equivalent analog resistor 20 and sends it to the controller 60. Based on the above embodiment, this electrical signal can characterize the charging pile's fault condition. Therefore, the controller 60 can determine the charging pile's fault condition based on this electrical signal, thus realizing charging pile fault detection. For example, the controller 60 can compare the actually collected electrical signal with the electrical signal when the charging pile is not faulty, and determine that the charging pile has a fault if the two signals are inconsistent. The controller 60 can also pre-store reference electrical signals for several charging pile fault types and match the actually collected electrical signal with the pre-stored reference electrical signals. If a matching reference electrical signal exists, the controller 60 determines that the charging pile has a fault, and the fault type is the fault type corresponding to the matching reference electrical signal.

[0092] In one embodiment, the controller can close the second switch and open the first switch during the pre-charging phase of the charging pile to detect charging pile faults. By conducting testing during the pre-charging phase, the charging process can be avoided. Furthermore, testing during the pre-charging phase allows for timely disconnection of the charging pile's output when a fault is detected, preventing charging safety accidents caused by short circuits or other issues, thereby improving charging safety.

[0093] In one embodiment, as shown in FIG12, the controller 60 is also connected to the current sampling circuit 51 in the sampling circuit 50. The controller 60 is used to determine that the charging pile output is open when a current of 0 is detected.

[0094] For an introduction to the current sampling circuit, please refer to the description in the above embodiments, which will not be repeated here. If the current is 0, it means that even though the charging pile provides voltage, no current is transmitted to the output end of the charging gun. This situation is caused by an abnormal break in the charging path between the output end of the charging pile and the output end of the charging gun. Based on this, when the current flowing through the equivalent analog resistor obtained by the controller from the current sampling circuit is 0, it can be determined that the charging pile output is open.

[0095] In one embodiment, as shown in FIG12, the controller 60 is connected to the current sampling circuit 51. When the controller 60 detects that the current is equal to the ratio of the voltage provided by the charging pile to the preset resistor 40, it determines that the charging pile output is short-circuited.

[0096] Specifically, the preset resistor and the equivalent analog resistor are connected in series. Therefore, when the charging pile is working normally, the voltage U1 provided by the charging pile and the current I flowing through the equivalent analog resistor should conform to the following formula:

[0097] Among them, R a The resistance value of the equivalent analog resistor, R b This is the preset resistance value.

[0098] When the detected current equals the ratio of the voltage provided by the charging pile to the preset resistance, that is... This indicates that the current magnitude between the input and output terminals of the charging gun is only affected by the preset resistor. The current does not flow through the equivalent analog resistor, and the two ends of the equivalent analog resistor are short-circuited. At this time, it can be determined that the output terminal of the charging pile is short-circuited.

[0099] In one embodiment, as shown in FIG12, the controller 60 is connected to the current sampling circuit 51. The controller 60 determines that the charging pile output is short-circuited when it detects that the difference between the current and the reference current is greater than or equal to the current difference threshold.

[0100] Specifically, under fault testing conditions, when the charging pile does not malfunction, the current I collected by the sampling circuit should conform to the formula: When the charging pile output is short-circuited, the current flowing through the equivalent analog resistor is almost zero, while the current flowing through the series branch containing the preset resistor and the equivalent analog resistor is... In other words, a short circuit in the charging pile output indicates a larger current sampled by the sampling circuit compared to when the charging pile is functioning correctly. Based on this change, a short circuit can be identified when the difference between the actual sampled current and the reference current is greater than or equal to a current difference threshold. Specifically, the current difference threshold doesn't necessarily have to be a specific current value; it can be determined based on the output unit of the current. For example, if the reference current is in the range of several amperes and the measured current is in the range of milliamperes, the order of magnitude of the currents differs, and a difference exceeding the current threshold indicates a short circuit in the charging pile output.

[0101] In one embodiment, as shown in FIG12, the controller 60 is connected to the current sampling circuit 51. The controller 60 determines that the output impedance of the charging pile does not meet the charging safety requirements if the difference between the target resistance value and the preset resistance 40 is less than or equal to the short-circuit impedance safety threshold. The target resistance value R is determined by the current I and the voltage U1 provided by the charging pile.

[0102] The short-circuit impedance safety threshold refers to an impedance value that meets charging safety requirements. When the output impedance of a charging pile is too low, the stability of its output voltage and current may be affected by grid fluctuations or load changes. Fluctuations in the output voltage can impact the charging efficiency and lifespan of the vehicle battery and other loads. Furthermore, extremely low output impedance can generate excessive current, which can damage the charging pile and load, and potentially cause fires or other safety accidents. Insufficient output impedance can also lead to strong electromagnetic radiation during operation, interfering with loads and other electronic devices. Therefore, considering multiple factors, the output impedance of charging piles must be constrained to ensure charging safety and reliability.

[0103] The output impedance of the charging pile can be understood here as the resistance of the equivalent analog resistor. Given a voltage U1 provided by the charging pile, the current sampled by the current sampling circuit is I. According to Ohm's law, the total resistance of the series connection between the preset resistor and the equivalent analog resistor is... The total series resistance equals the sum of the preset resistance and the equivalent analog resistance. Since the preset resistance is known, the controller subtracts the target resistance from the preset resistance to obtain the equivalent analog resistance (the output impedance of the charging pile). This result is compared with the short-circuit impedance safety threshold. If the difference between the target resistance and the preset resistance is greater than the short-circuit impedance safety threshold, it indicates that the charging safety requirements are met. Conversely, if the difference between the target resistance and the preset resistance is less than or equal to the short-circuit impedance safety threshold, it indicates that the charging pile may experience the various charging safety problems mentioned above, and the controller can determine that the output impedance of the charging pile does not meet the charging safety requirements.

[0104] In one embodiment, when the current sampling circuit includes a current transformer, the output of the current transformer is connected to the controller.

[0105] In one embodiment, as shown in Figures 13-14, the charging pile fault detection circuit further includes a voltage sampling circuit 52. The controller 60 is connected to the voltage sampling circuit 52.

[0106] The voltage sampling circuit 52 is used to sample the voltage applied to the output terminal of the charging gun.

[0107] In one embodiment, as shown in Figures 13-14, based on the connection between the controller 60 and the voltage sampling circuit 52, the controller 60 is used to determine that the charging pile output is short-circuited when the charging pile provides voltage and the voltage at the output end of the charging gun is 0.

[0108] When the charging station is not malfunctioning, based on the series relationship between the preset resistor 40 and the equivalent analog resistor 20, the voltage U2 (the voltage applied across the equivalent analog resistor) supplied by the charging station to the output terminal of the charging gun should conform to the formula: U1 is the voltage provided by the charging station, R a The resistance value of the equivalent analog resistor, R b This is the preset resistance value.

[0109] When the charging pile is functioning correctly, the output test voltage U1 is not zero. Based on the formula above, the voltage U2 across the equivalent analog resistor is also not zero. If the charging pile output is short-circuited, meaning the equivalent analog resistor is short-circuited, the current flowing through the equivalent analog resistor is zero. According to Ohm's law, the voltage across the equivalent analog resistor (the voltage at the output of the charging gun) is zero. Therefore, the controller can determine if the charging pile output is short-circuited when the voltage at the output of the charging gun is zero. This fault detection process requires no complex calculations; it only requires monitoring whether the voltage at the output of the charging gun is zero to determine if a short-circuit fault has occurred in the charging pile output, resulting in fast detection speed.

[0110] In one embodiment, as shown in Figures 13-14, the controller 60 is connected to the voltage sampling circuit 52. Based on the connection between the controller 60 and the voltage sampling circuit 52, the controller 60 is used to determine that the charging pile output is open when the voltage at the output of the charging gun is equal to the voltage provided by the charging pile.

[0111] Specifically, assuming the charging station is not malfunctioning, according to Ohm's law, the formula should be satisfied. When the charging station's output is open-circuited, the equivalent analog resistance value R a When the voltage is infinite, U2 equals U1. Therefore, when the voltage at the output of the charging gun equals the voltage provided by the charging pile, the controller can quickly determine that the charging pile output is open-circuited.

[0112] In one embodiment, the controller is connected to the charging pile, and the controller is also used to control the charging pile to stop outputting voltage in the event that a fault is determined to be in the charging pile.

[0113] There are several ways to control the charging pile to stop outputting voltage. For example, disconnecting the charging pile from the charging gun, disconnecting the external power supply from the charging pile, or stopping the voltage conversion circuit in the charging pile from working. These are not exhaustive examples.

[0114] The charging pile fault detection circuit provided in this application can prevent the components in the circuit from burning out by controlling the charging pile to stop outputting voltage in the event of a charging pile output fault, thereby improving the service life of the charging pile and charging gun and ensuring electrical safety.

[0115] In one embodiment, the controller is connected to a sampling resistor in the voltage sampling circuit. As described in the above embodiments, the resistance of the voltage divider resistor unit is greater than the resistance of the sampling resistor, and the voltage divider resistor unit and the sampling resistor are connected in series. Under series voltage division, since the sampling resistor is small, the voltage it receives is also small. Therefore, even when the current flowing through the voltage sampling circuit is large, the voltage across the sampling resistor can still remain at a low level, avoiding overload of the controller port connected to the sampling resistor. That is, the voltage sampling circuit provided in this application embodiment, by using a series voltage divider resistor unit and a sampling resistor, can avoid signal distortion or overload when the controller receives the collected voltage. The smaller voltage obtained by the controller port from the sampling resistor also reduces the power consumption and heat of the circuit.

[0116] In one embodiment, as shown in Figures 6, 7, and 9, the first switch 10 can be located between the positive input terminal Input+ and the positive output terminal Output+ of the charging gun.

[0117] In one embodiment, as shown in Figures 5, 8, and 10, the first switch 10 can also be located between the negative input terminal Input- and the negative output terminal Output- of the charging gun.

[0118] In one embodiment, as shown in Figures 5-10, the charging pile fault detection circuit further includes a third switch 70, which, along with the first switch 10, is respectively disposed on the positive and negative transmission lines of the charging gun. For example, as shown in Figures 5, 8, and 10, a third switch 70 can be connected in series between the positive input terminal Input+ and the positive output terminal Output+ of the charging gun, and a first switch 10 can be connected in series between the negative input terminal Input- and the negative output terminal Output- of the charging gun. Alternatively, as shown in Figures 6, 7, and 9, a first switch 10 can be connected in series between the positive input terminal Input+ and the positive output terminal Output+ of the charging gun, and a third switch 70 can be connected in series between the negative input terminal Input- and the negative output terminal Output- of the charging gun.

[0119] In one embodiment, in the charging pile fault detection circuit, the controller is also connected to a third switch. Before fault detection, the first switch and the third switch can be alternately turned on. In the alternating on mode, if neither the first switch nor the third switch is stuck, then at any given time, since only one of the first switch and the third switch is closed, a circuit cannot be formed. Based on this characteristic, a sampling circuit can be used to collect the current flowing through the circuit where the first switch and the third switch are located. The collected current is used to monitor whether the first switch and the third switch can be turned on and off normally, so as to prevent false detections caused by switch sticking during subsequent charging pile fault detection.

[0120] In one embodiment, a current sampling circuit can be connected in series in the circuit containing the first and third switches. If neither the first nor the third switch is stuck together, during the alternating conduction of the first and third switches, the circuit containing the first and third switches is closed, and the current sampled by the current sampling circuit should always be 0. Conversely, if the current sampled by the current sampling circuit is not 0, it indicates that at least one of the first and third switches is stuck together, causing both switches to conduct simultaneously. Optionally, the controller can be connected to the current sampling circuit in the circuit containing the first and third switches. The controller can also be connected to the first and third switches themselves. The controller controls the first and third switches to conduct alternately and acquires the current sampled by the current sampling circuit in the circuit. If the current remains 0, it indicates that the first and third switches are not stuck together; if the current is not 0, it indicates that at least one of the first and third switches is stuck together.

[0121] The charging pile fault detection circuit provided in this application embodiment can also improve the electrical safety of the charging pile by setting up dual switches on the positive and negative lines.

[0122] In one embodiment, the charging pile fault detection circuit further includes an alarm module (not shown). The alarm module is used to output alarm information in the event of a charging pile fault.

[0123] Among them, the alarm module is selected based on the principle of being able to effectively alert users to charging pile malfunctions.

[0124] Optionally, the alarm module may include, but is not limited to, audible and visual alarms, displays, etc., installed on the charging pile or charging gun. The alarm module may also include communication modules, and the corresponding alarm action may be to output the fault status data of the charging pile to the terminal, so that staff can view it through terminals such as mobile phones and computers, and perform timely maintenance, shorten the fault repair cycle of the charging pile, and thus improve the effective use time of the charging pile.

[0125] In one embodiment, the fault condition of the charging pile determined by the controller can be output as a result signal. For example, the result signal can be a data signal carrying data such as "output short circuit", "output open circuit", "impedance mismatch", etc., or it can be an electrical signal such as high or low level.

[0126] When the result signal is a data signal, the alarm module can be a display on the charging pile. The controller outputs the result signal to the display, and the display generates and displays the alarm information corresponding to the result signal to remind the user of the charging pile malfunction.

[0127] When the resulting signal is an electrical signal, the alarm module can be a fault indicator light on the charging pile and / or charging gun. The controller outputs an electrical signal to the fault indicator light to trigger it to illuminate, thus alerting the user to a charging pile malfunction using an optical signal-type alarm message. Optionally, the alarm module can also include multiple fault indicator lights. Under different charging pile output fault conditions, the controller can output electrical signals to the corresponding fault indicator lights to trigger them to illuminate. Different indicator lights illuminating indicate different types of charging pile malfunctions.

[0128] The charging pile fault detection circuit provided in this application embodiment can switch the branches in the charging pile fault detection circuit by switching the on and off states of the first switch and the second switch. Combined with the current and voltage data collected by the sampling circuit, the charging pile output fault situation can be determined.

[0129] Furthermore, the charging pile fault detection circuit provided in this application embodiment can directly determine the fault condition of the charging pile through current and voltage sampling, exhibiting extremely high identification accuracy for short-circuit faults and insulation faults at the charging pile output terminal. Since the charging pile fault detection circuit provided in this application embodiment can determine the charging pile fault condition without complex calculations, it can shorten the detection time and effectively improve the utilization efficiency of the charging pile. The charging pile fault detection circuit provided in this application embodiment uses the voltage output from the charging pile output terminal as the test voltage under fault test conditions, fully utilizing the functions of the charging pile's internal components without requiring an additional test voltage, thus optimizing the circuit structure. In addition, the charging pile fault detection circuit provided in this application embodiment can be used for fault detection of both AC and DC charging piles, with a wide range of applications.

[0130] In one embodiment, a charging gun is provided, including the aforementioned charging pile fault detection circuit.

[0131] A charging gun equipped with the aforementioned charging pile fault detection circuit can detect charging pile faults when connected to a charging pile. It can also control the charging pile to stop output when a fault occurs, making it widely applicable to various types of charging piles and facilitating safety upgrades of existing charging piles.

[0132] In one embodiment, a charging device is provided, comprising: a charging pile and a charging gun as described in the above embodiment. The output end of the charging pile is connected to the input end of the charging gun, and the output end of the charging gun is used to connect to the device to be charged.

[0133] The charging device provided in this application embodiment, based on the aforementioned charging pile fault detection circuit, can detect charging pile faults and stop charging output in the event of a charging pile fault, protecting equipment components from damage and improving service life and electrical safety. Furthermore, in the event of a charging pile fault, an alarm can shorten the repair cycle and alert charging users to the fault, further enhancing electrical safety.

[0134] In the description of this specification, references to terms such as "some embodiments," "other embodiments," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative descriptions of the above terms do not necessarily refer to the same embodiments or examples.

[0135] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0136] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these modifications and improvements all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A charging pile fault detection circuit, characterized in that, The charging pile fault detection circuit includes: The first switch, the input terminal of the first switch is connected to the input terminal of the charging gun; An equivalent analog resistor is provided, with its input terminal connected to the output terminal of the first switch and its output terminal connected to the output terminal of the charging gun. The second switch has a different on / off state than the first switch; A preset resistor is connected in series with the second switch between the input terminal of the charging gun and the equivalent analog resistor; A sampling circuit is used to sample the electrical signal applied to the equivalent analog resistor, and the electrical signal is used to characterize the fault condition of the charging pile.

2. The charging pile fault detection circuit according to claim 1, characterized in that, The sampling circuit includes at least one of the following circuits: A current sampling circuit is used to detect the current flowing through the equivalent analog resistor; A voltage sampling circuit is used to sample the voltage applied to the output terminal of the charging gun.

3. The charging pile fault detection circuit according to claim 2, characterized in that, The current sampling circuit includes: A current transformer for detecting the current flowing through the equivalent analog resistance.

4. The charging pile fault detection circuit according to claim 3, characterized in that, The coil of the current transformer is coupled to the series branch containing the second switch and the preset resistor.

5. The charging pile fault detection circuit according to claim 2, characterized in that, The voltage sampling circuit includes: Voltage divider resistor unit; A sampling resistor is provided, wherein the sampling resistor and the voltage divider resistor unit are connected in series and then in parallel across the equivalent analog resistor, and the resistance value of the sampling resistor is less than the resistance value of the voltage divider resistor unit.

6. The charging pile fault detection circuit according to claim 1, characterized in that, The preset resistor is a fixed current-limiting resistor or a positive temperature coefficient resistor.

7. The charging pile fault detection circuit according to any one of claims 1-6, characterized in that, Also includes: The controller is connected to the first switch, the second switch and the sampling circuit respectively. The controller is used to control the second switch to close and the first switch to open, and to determine the fault status of the charging pile based on the electrical signal.

8. The charging pile fault detection circuit according to claim 7, characterized in that, In the case of including a current sampling circuit, the controller is connected to the current sampling circuit; The controller is configured to determine that the charging pile output is open-circuited when the current is detected to be 0; or, the controller is configured to determine that the charging pile output is short-circuited when the current is equal to the ratio of the voltage provided by the charging pile to the preset resistance, or when the difference between the current and the reference current is greater than or equal to a current difference threshold; or, the controller is configured to determine that the output impedance of the charging pile does not meet the charging safety requirements when the resistance difference between the target resistance value and the preset resistance is less than or equal to a short-circuit impedance safety threshold, wherein the target resistance value is determined by the current and the voltage provided by the charging pile.

9. The charging pile fault detection circuit according to claim 7, characterized in that, When the sampling circuit includes a voltage sampling circuit, the controller is connected to the voltage sampling circuit, wherein the controller is used to determine that the charging pile output is short-circuited when the charging pile provides voltage and the voltage at the output terminal of the charging gun is 0; or, when the voltage at the output terminal of the charging gun is equal to the voltage provided by the charging pile, the charging pile output is open-circuited.

10. The charging pile fault detection circuit according to claim 7, characterized in that, The controller is connected to the charging pile, and the controller is also used to control the charging pile to stop outputting voltage when a fault is determined to be in the charging pile.

11. The charging pile fault detection circuit according to any one of claims 1-10, characterized in that, The charging pile fault detection circuit also includes: An alarm module is used to output alarm information in the event of a fault in the charging pile.

12. A charging gun, characterized in that, Includes the charging pile fault detection circuit as described in any one of claims 1-11.

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