Charging pile and detection method of output short circuit thereof

Abstract

The application discloses a charging pile and a detection method for output short circuit of the charging pile. The charging pile comprises a main circuit resistor, a short circuit detection branch, an electric energy metering branch and a control module; the first end of the main circuit resistor is connected with the input end of the charging pile; the short circuit detection branch is connected with the output end of the charging pile; the electric energy metering branch is connected with the second end of the main circuit resistor and the short circuit detection branch; the control module is connected with the electric energy metering branch; the short circuit detection branch comprises a detection relay group; the control module is connected with the control end of the detection relay group. The resistance value of the output end of the charging pile is calculated by the current on the electric energy metering branch before and after the closure of the detection relay group, the resistance on the main circuit resistor, the electric energy metering branch and the short circuit detection branch, and whether the output end of the charging pile is short-circuited is determined according to the resistance value of the output end of the charging pile. The structure is simple and easy to realize.

Description

Technical Field

[0001] This invention relates to the field of charging pile technology, and in particular to a method for detecting short circuits in charging piles and their outputs. Background Technology

[0002] Charging stations can charge various models of electric vehicles according to different voltage levels.

[0003] The input end of a charging station is directly connected to the AC power grid, and the output end is equipped with a charging plug for charging electric vehicles. Charging stations are currently divided into AC charging stations and DC charging stations, with AC charging stations being more common. In AC charging stations, the neutral and live wires are connected to the AC power grid's neutral and live wires respectively through relay contacts. When the relay contacts are closed, the charging station starts charging the electric vehicle. However, if a short circuit occurs at the output of the AC charging station, directly closing the relay contacts to charge the electric vehicle can easily lead to a safety accident. Summary of the Invention

[0004] This invention provides a method for detecting short circuits in charging piles and their output circuits. By adding a short circuit detection branch to the existing charging pile circuit, the output circuit of the charging pile can be tested. This method is low-cost and prevents the main circuit of the charging pile from charging the car under short circuit faults, thus avoiding safety accidents.

[0005] According to one aspect of the present invention, a charging pile is provided, comprising: a main circuit resistor, a short circuit detection branch, an energy metering branch, and a control module;

[0006] The first end of the main circuit resistor is connected to the input end of the charging pile;

[0007] The short-circuit detection branch is connected to the output terminal of the charging pile;

[0008] The power metering branch is connected to the second terminal of the main circuit resistor and the short circuit detection branch, respectively.

[0009] The control module is connected to the power metering branch and is used to acquire the current in the power metering branch;

[0010] The short-circuit detection branch includes a detection relay group, and the control module is connected to the control terminal of the detection relay group;

[0011] The control module is used to acquire the current on the power metering branch under the first operating condition of the charging pile and the current on the power metering branch under the second operating condition of the charging pile. It is also used to calculate the resistance value of the charging pile output terminal based on the current on the power metering branch under the first operating condition, the current on the power metering branch under the second operating condition, the main circuit resistance, the resistance on the power metering branch, and the resistance on the short circuit detection branch. When the resistance value of the charging pile output terminal is less than a set resistance threshold, it determines that the charging pile output terminal is short-circuited. In the first operating condition, the detection relay group is open, and in the second operating condition, the detection relay group is closed.

[0012] Optionally, the input terminal of the charging pile includes a first input terminal and a second input terminal, and the output terminal of the charging pile includes a first output terminal and a second output terminal; the power metering branch includes a first acquisition terminal and a second acquisition terminal;

[0013] The main circuit resistor includes a first resistor connected between the first input terminal and the first acquisition terminal, and / or a second resistor connected between the second input terminal and the second acquisition terminal;

[0014] The detection relay group includes a first relay connected between the first output terminal and the first acquisition terminal, and / or a second relay connected between the second output terminal and the second acquisition terminal;

[0015] The short-circuit detection branch further includes a third resistor connected between the first output terminal and the first acquisition terminal, and / or a fourth resistor connected between the second output terminal and the second acquisition terminal; the energy metering branch includes a current transformer, a seventh resistor, and an energy metering chip. The first end of the primary coil of the current transformer is connected to the first acquisition terminal, the second end of the primary coil of the current transformer is connected to the second acquisition terminal, the first end of the seventh resistor is connected to the first end of the secondary coil of the current transformer, the second end of the seventh resistor is connected to the second end of the secondary coil of the current transformer, the first end of the secondary coil of the current transformer is also connected to the detection terminal of the energy metering chip, and the output terminal of the energy metering chip is connected to the control module; the energy metering branch further includes a fifth resistor connected between the first end of the primary coil of the current transformer and the first acquisition terminal, and / or a sixth resistor connected between the second end of the primary coil of the current transformer and the second acquisition terminal;

[0016] The control module is connected to the control terminal of the first relay and the control terminal of the second relay, respectively.

[0017] Optionally, the charging pile further includes a charging and discharging relay group, which is connected between the input and output terminals of the charging pile.

[0018] The control module is connected to the control terminal of the charging and discharging relay group. The control module is used to control the charging and discharging relay group to disconnect when it determines that the output terminal of the charging pile is short-circuited and a charging command is received.

[0019] According to another aspect of the present invention, a method for detecting a short circuit in the output of a charging pile is provided, which is applied to the charging pile described in any of the above claims, wherein the method for detecting a short circuit in the output of the charging pile is executed by the control module;

[0020] The method for detecting short circuits in the charging pile output includes:

[0021] The current on the power metering branch of the charging pile is obtained under the first operating condition; under the first operating condition, the detection relay group is disconnected;

[0022] The current on the power metering branch of the charging pile is obtained under the second operating condition; under the second operating condition, the detection relay group is closed;

[0023] The resistance value at the output terminal of the charging pile is calculated based on the current in the power metering branch under the first operating condition, the current in the power metering branch under the second operating condition, the main circuit resistance, the resistance in the power metering branch, and the resistance in the short circuit detection branch.

[0024] When the resistance at the output terminal of the charging pile is less than a set resistance threshold, it is determined that the output terminal of the charging pile is short-circuited.

[0025] Optionally, the resistance value at the output terminal of the charging pile is calculated based on the current in the energy metering branch under the first operating condition, the current in the energy metering branch under the second operating condition, the main circuit resistance, the resistance in the energy metering branch, and the resistance in the short-circuit detection branch, including:

[0026] The branch voltage is calculated based on the current and resistance on the power metering branch under the second operating condition; wherein the branch voltage is the sum of the voltage across the short-circuit detection branch and the voltage across the resistor at the output terminal of the charging pile.

[0027] The current in the short-circuit detection branch under the second operating condition is calculated based on the current in the power metering branch under the second operating condition, the current in the power metering branch under the first operating condition, the main circuit resistance, the resistance in the power metering branch, and the resistance in the short-circuit detection branch.

[0028] Under the second operating condition, the resistance value of the charging pile output terminal is calculated based on the branch voltage and the current in the short-circuit detection branch.

[0029] Optionally, the charging pile has an input terminal including a first input terminal and a second input terminal, and an output terminal including a first output terminal and a second output terminal; the energy metering branch includes a first acquisition terminal and a second acquisition terminal, and the main circuit resistor includes a first resistor connected between the first input terminal and the first acquisition terminal, and / or a second resistor connected between the second input terminal and the second acquisition terminal; the detection relay group includes a first relay connected between the first output terminal and the first acquisition terminal, and / or a second relay connected between the second output terminal and the second acquisition terminal; the short circuit detection branch further includes a third resistor connected between the first output terminal and the first acquisition terminal, and / or a fourth resistor connected between the second output terminal and the second acquisition terminal; the energy metering branch includes a current transformer, a seventh resistor, and an energy metering core. The current transformer has a first terminal connected to the first acquisition terminal and a second terminal connected to the second acquisition terminal. A seventh resistor has a first terminal connected to the first terminal of the secondary coil of the current transformer and a second terminal connected to the second terminal of the secondary coil. The first terminal of the secondary coil is also connected to the detection terminal of the energy metering chip. The output terminal of the energy metering chip is connected to the control module. The energy metering branch also includes a fifth resistor connected between the first terminal of the primary coil of the current transformer and the first acquisition terminal, and / or a sixth resistor connected between the second terminal of the primary coil of the current transformer and the second acquisition terminal. The control module is connected to the control terminals of the first relay and the second relay, respectively.

[0030] Based on the current and resistance of the energy metering branch under the second operating condition, the branch voltage is calculated, including:

[0031] The branch voltage is calculated based on the voltage at the detection terminal of the power metering chip under the second operating condition, the seventh resistor, and the resistance between the first acquisition terminal and the second acquisition terminal.

[0032] Optionally, the branch voltage is calculated based on the voltage at the detection terminal of the energy metering chip under the second operating condition, the seventh resistor, and the resistance between the first acquisition terminal and the second acquisition terminal, including:

[0033] Under the second operating condition, the current on the secondary coil of the current transformer is calculated based on the voltage at the detection terminal of the power metering chip and the seventh resistor.

[0034] Under the second operating condition, the current on the primary winding of the current transformer is calculated based on the current on the secondary winding of the current transformer and the turns ratio of the primary winding and the secondary winding of the current transformer.

[0035] The branch voltage is calculated based on the current on the primary winding of the current transformer under the second operating condition and the resistance between the first acquisition terminal and the second acquisition terminal.

[0036] Optionally, the current in the short-circuit detection branch under the second operating condition is calculated based on the current in the energy metering branch under the second operating condition, the current in the energy metering branch under the first operating condition, the main circuit resistance, the resistance in the energy metering branch, and the resistance in the short-circuit detection branch, including:

[0037] Based on the voltage at the detection terminal of the energy metering chip under the second operating condition and the seventh resistor, calculate the current on the primary coil of the current transformer under the second operating condition.

[0038] The current in the main circuit resistor under the second operating condition is calculated based on the voltage at the detection terminal of the power metering chip under the second operating condition, the voltage at the detection terminal of the power metering chip under the first operating condition, the main circuit resistor, the seventh resistor, and the resistance between the first acquisition terminal and the second acquisition terminal.

[0039] Under the second operating condition, the current on the short-circuit detection branch is calculated based on the current on the primary winding of the current transformer and the current on the main circuit resistor.

[0040] Optionally, based on the voltage at the detection terminal of the energy metering chip under the second operating condition, the voltage at the detection terminal of the energy metering chip under the first operating condition, the main circuit resistance, the seventh resistor, and the resistance between the first acquisition terminal and the second acquisition terminal, the current on the main circuit resistance under the second operating condition is calculated, including:

[0041] Based on the voltage at the detection end of the power metering chip under the first operating condition, the seventh resistor, the main circuit resistor, and the resistance between the first acquisition end and the second acquisition end, the voltage at the input end of the charging pile under the second operating condition is calculated.

[0042] The branch voltage is calculated based on the current on the primary winding of the current transformer under the second operating condition and the resistance between the first and second acquisition terminals.

[0043] The current in the main circuit resistor is calculated based on the voltage at the input terminal of the charging pile, the branch voltage, and the main circuit resistance under the second operating condition.

[0044] Optionally, the charging pile further includes a charging and discharging relay group, which is connected between the input and output terminals of the charging pile, and the control module is connected to the control terminal of the charging and discharging relay group.

[0045] After determining that the output terminal of the charging pile is short-circuited and receiving a charging command, the charging and discharging relay group is controlled to disconnect.

[0046] The technical solution of this invention calculates the resistance value at the output terminal of the charging pile by measuring the current, main circuit resistance, and resistance on the power metering branch before and after the closed detection relay group, as well as the resistance on the short-circuit detection branch. Based on the magnitude of this resistance value, it determines whether a short circuit has occurred at the charging pile's output terminal. This method only requires adding a short-circuit detection branch to the existing charging pile circuit to determine if a short circuit exists. It is simple in structure, easy to implement, and has low cost.

[0047] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of the present invention, nor is it intended to limit the scope of the invention. Other features of the invention will become readily apparent from the following description. Attached Figure Description

[0048] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0049] Figure 1 A circuit diagram of a charging pile provided in an embodiment of the present invention;

[0050] Figure 2 A flowchart illustrating a method for detecting a short circuit at the output of a charging pile, as provided in an embodiment of the present invention;

[0051] Figure 3 A flowchart of another method for detecting a short circuit at the output of a charging pile provided in an embodiment of the present invention;

[0052] Figure 4 This is a circuit equivalent diagram of a charging pile under a second operating condition provided by an embodiment of the present invention;

[0053] Figure 5 This is a circuit equivalent diagram of a charging pile under the first operating condition, provided as an embodiment of the present invention. Detailed Implementation

[0054] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0055] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0056] This invention provides a charging pile, which includes: a main circuit resistor, a short circuit detection branch, an energy metering branch, and a control module;

[0057] The first end of the main circuit resistor is connected to the input end of the charging pile;

[0058] The short-circuit detection branch is connected to the output terminal of the charging pile;

[0059] The power metering branch is connected to the second terminal of the main circuit resistor and the short circuit detection branch respectively;

[0060] The control module is connected to the electricity metering branch and is used to obtain the current in the electricity metering branch;

[0061] The short-circuit detection branch includes a detection relay group, and the control module is connected to the control terminal of the detection relay group;

[0062] The control module is used to acquire the current in the energy metering branch of the charging pile under the first operating condition and the current in the energy metering branch of the charging pile under the second operating condition. It is also used to calculate the resistance value at the output terminal of the charging pile based on the current in the energy metering branch under the first and second operating conditions, the main circuit resistance, the resistance in the energy metering branch, and the resistance of the first branch. If the resistance value at the output terminal of the charging pile is less than a set resistance threshold, it determines that the output terminal of the charging pile is short-circuited. Specifically, under the first operating condition, the detection relay group is open; under the second operating condition, the detection relay group is closed.

[0063] The short-circuit detection branch and the power metering branch are connected in parallel to the main circuit of the charging pile.

[0064] In the second operating condition, the detection relay group is closed, and the short-circuit detection branch is connected to the charging pile. In the first operating condition, the detection relay group is open, and the short-circuit detection branch is not connected to the charging pile. When the detection relay group is open, the main circuit of the charging pile includes the main circuit resistance and the energy metering branch. The current in the energy metering branch is the main circuit current. Therefore, the input voltage of the charging pile can be obtained based on the current in the energy metering branch, the main circuit resistance, and the resistance in the energy metering branch when the detection relay group is open (first operating condition). When the detection relay group is closed (second operating condition), the voltage across the short-circuit detection branch is equal to the voltage across the energy metering branch. The voltage across the short-circuit detection branch can be determined based on the current in the energy metering branch and the resistance in the energy metering branch when the detection relay group is closed. In the second operating condition, the current in the short-circuit detection branch can be determined based on the current in the main circuit resistance and the current in the energy metering branch. In the second operating condition, the current in the main circuit resistor is equal to the difference between the voltage at the input terminal of the charging pile and the voltage at both ends of the short-circuit detection branch, divided by the main circuit resistor.

[0065] When the detection relay group is closed, the voltage across the short-circuit detection branch is equal to the sum of the voltage across the resistor in the short-circuit detection branch and the voltage across the resistor at the charging pile output terminal. Therefore, based on the voltage across the short-circuit detection branch when the detection relay group is closed, the current in the short-circuit detection branch, and the resistance value of the resistor in the short-circuit detection branch, the resistance value at the charging pile output terminal can be calculated. If a short circuit occurs at the charging pile output terminal, the resistance value at the charging pile output terminal will be very small. A short circuit at the charging pile output terminal is determined when the resistance value is less than the set resistance threshold. A short circuit is determined when the resistance value at the charging pile output terminal is greater than or equal to the set resistance threshold.

[0066] The resistance threshold setting is related to the on-board charger connected to the output end of the charging pile. The resistance threshold setting can be adjusted according to different on-board chargers, making it flexible in application and improving the accuracy of output short circuit detection under different on-board chargers.

[0067] The technical solution of this invention calculates the resistance value at the output terminal of the charging pile by measuring the current, main circuit resistance, and resistance on the power metering branch before and after the closed detection relay group, as well as the resistance on the short-circuit detection branch. Based on the magnitude of this resistance value, it determines whether a short circuit has occurred at the charging pile's output terminal. This method only requires adding a short-circuit detection branch to the existing charging pile circuit to determine if a short circuit exists. It is simple in structure, easy to implement, and has low cost.

[0068] Figure 1 This is a circuit diagram of a charging pile provided in an embodiment of the present invention, with reference to... Figure 1 The charging pile's input terminals include a first input terminal L_IN and a second input terminal N_IN, and its output terminals include a first output terminal L_OUT and a second output terminal N_OUT; the power metering branch includes a first acquisition terminal a1 and a second acquisition terminal a2.

[0069] The detection relay group includes a first relay K1 connected between the first output terminal L_OUT and the first acquisition terminal a1, and / or a second relay K2 connected between the second output terminal N_OUT and the second acquisition terminal a2;

[0070] The main circuit resistors include a first resistor R1 connected between the first input terminal L_IN and the first acquisition terminal a1, and / or a second resistor R2 connected between the second input terminal N_IN and the second acquisition terminal a2;

[0071] The short-circuit detection branch also includes a third resistor R3 connected between the first output terminal L_OUT and the first acquisition terminal a1, and / or a fourth resistor R4 connected between the second output terminal N_OUT and the second acquisition terminal a2; the energy metering branch includes a current transformer T1, a seventh resistor R7, and an energy metering chip 1. The first end of the primary winding of the current transformer T1 is connected to the first acquisition terminal a1, the second end of the primary winding of the current transformer T1 is connected to the second acquisition terminal a2, the first end of the seventh resistor R7 is connected to the first end of the secondary winding of the current transformer T1, and the second end of the seventh resistor R7 is connected to the second end of the secondary winding of the current transformer T1. The first end of the secondary coil of current transformer T1 is connected to the detection terminal VP of energy metering chip 1 through the eighth resistor R8. The second end of the secondary coil of current transformer T1 is grounded to GND. The grounding terminal G of energy metering chip 1 is grounded to GND. A capacitor C1 is connected between the detection terminal VP and the grounding terminal G of energy metering chip 1. The output terminal UART of energy metering chip 1 is connected to control module 2. The energy metering branch also includes a fifth resistor R5 connected between the first end of the primary coil of current transformer T1 and the first acquisition terminal a1, and / or a sixth resistor R6 connected between the second end of the primary coil of current transformer T1 and the second acquisition terminal a2.

[0072] The control module 2 is connected to the control terminal of the first relay K1 and the control terminal of the second relay K2.

[0073] There can be a resistor Rout between the first output terminal L_OUT and the second output terminal N_OUT of the charging pile. When the output terminal of the charging pile is short-circuited, the resistance of Rout is small; when there is no short circuit, the resistance of Rout is large. Therefore, the presence of a short circuit at the output terminal of the charging pile can be determined by calculating the resistance of Rout.

[0074] Continue to refer to Figure 1 Optionally, the charging pile also includes a charging and discharging relay group, which is connected between the input and output terminals of the charging pile.

[0075] Control module 2 is connected to the control terminal of the charging and discharging relay group. Control module 2 is used to control the charging and discharging relay group to disconnect when it is determined that the output terminal of the charging pile is short-circuited and a charging command is received.

[0076] The charging / discharging relay group includes a third relay K3 and a fourth relay K4. The third relay K3 is connected between the first input terminal L_IN and the first output terminal L_OUT of the charging pile, and the fourth relay K4 is connected between the second input terminal N_IN and the second output terminal N_OUT of the charging pile. The control module 2 is connected to the control terminals of the third relay K3 and the fourth relay K4, respectively. The first output terminal L_OUT and the second output terminal N_OUT of the charging pile are used to connect to the on-board charger.

[0077] When the control module 2 determines that there is a short circuit at the output terminal of the charging pile based on the resistance value at the output terminal, it issues an alarm signal and controls the third relay K3 and the fourth relay K4 to disconnect, preventing the next step of the charging process from proceeding, thus avoiding a safety accident caused by continuing charging when there is a short circuit at the output terminal of the charging pile.

[0078] This invention also provides a method for detecting short circuits in the output of a charging pile, applicable to charging piles in any of the above embodiments, and the method is executed by the control module in the charging pile. Figure 2 A flowchart of a method for detecting a short circuit at the output of a charging pile, as provided in an embodiment of the present invention, is shown below. Figure 2 Optional methods for detecting short circuits in the charging pile output include:

[0079] S110: Obtain the current on the power metering branch of the charging pile under the first operating condition; under the first operating condition, the detection relay group is disconnected.

[0080] When the detection relay group is disconnected, there are only the main circuit resistance and the power metering branch on the main circuit of the charging pile. The voltage at the input terminal of the charging pile can be calculated based on the current in the power metering branch, the main circuit resistance, and the power metering branch resistance under the first working condition.

[0081] S120: Obtain the current on the power metering branch of the charging pile under the second operating condition; under the second operating condition, detect the closure of the relay group.

[0082] When the detection relay group is closed, the power metering branch and the short circuit detection branch are connected in parallel to the main circuit of the charging pile. The voltage across the short circuit detection branch can be calculated based on the current and resistance of the power metering branch under the second operating condition.

[0083] S130: Calculate the resistance value at the output terminal of the charging pile based on the current in the power metering branch under the first operating condition, the current in the power metering branch under the second operating condition, the main circuit resistance, the resistance in the power metering branch, and the resistance in the short circuit detection branch.

[0084] When the detection relay group is closed, the current in the short-circuit detection branch can be determined based on the current in the main circuit resistor and the current in the energy metering branch. Specifically, the current in the main circuit resistor is equal to the difference between the voltage at the charging pile input terminal and the voltage across the short-circuit detection branch, divided by the main circuit resistor. The voltage at the charging pile input terminal is equal before and after the detection relay group is closed.

[0085] When the detection relay group is closed, the voltage across the short-circuit detection branch is equal to the sum of the voltage across the resistor in the short-circuit detection branch and the voltage across the resistor at the output end of the charging pile. Therefore, based on the voltage across the short-circuit detection branch, the current in the short-circuit detection branch, and the resistance value of the resistor in the short-circuit detection branch when the detection relay group is closed, the resistance value at the output end of the charging pile can be calculated.

[0086] S140: When the resistance at the output terminal of the charging pile is less than the set resistance threshold, it is determined that the output terminal of the charging pile is short-circuited.

[0087] The technical solution of this invention calculates the resistance at the output terminal of the charging pile by measuring the current before the closed detection relay group and in the power metering branch of the closed detection relay group, as well as the resistance of the main circuit, the resistance of the power metering branch, and the resistance of the short circuit detection branch. Based on the resistance value at the output terminal of the charging pile, it determines whether a short circuit has occurred. This method only requires adding a short circuit detection branch to the existing circuit of the charging pile to determine whether a short circuit exists. It is simple in structure, easy to implement, and has low cost.

[0088] Figure 3 A flowchart illustrating another method for detecting a short circuit at the output of a charging pile, as provided in an embodiment of the present invention. Figure 4This is a circuit equivalent diagram of a charging pile under a second operating condition provided by an embodiment of the present invention. Figure 5 This is a circuit equivalent diagram of a charging pile under a first operating condition provided by an embodiment of the present invention, with reference to... Figure 1 , Figures 3-5 Optionally, the charging pile's input terminals include a first input terminal L_IN and a second input terminal N_IN, and the charging pile's output terminals include a first output terminal L_OUT and a second output terminal N_OUT; the energy metering branch includes a first acquisition terminal a1 and a second acquisition terminal a2; the detection relay group includes a first relay K1 connected between the first output terminal L_OUT and the first acquisition terminal a1, and / or a second relay K2 connected between the second output terminal N_OUT and the second acquisition terminal a2; the main circuit resistor includes a first resistor R1 connected between the first input terminal L_IN and the first acquisition terminal a1, and / or a second resistor R2 connected between the second input terminal N_IN and the second acquisition terminal a2; the short-circuit detection branch further includes a third resistor R3 connected between the first output terminal L_OUT and the first acquisition terminal a1, and / or a fourth resistor R4 connected between the second output terminal N_OUT and the second acquisition terminal a2; the energy metering branch includes a current transformer T1, a seventh resistor R7, and an energy metering chip 1, and the first terminal of the primary coil of the current transformer T1... The first acquisition terminal a1 is connected to the second acquisition terminal a2. The second end of the primary coil of the current transformer T1 is connected to the second acquisition terminal a2. The first end of the seventh resistor R7 is connected to the first end of the secondary coil of the current transformer T1. The second end of the seventh resistor R7 is connected to the second end of the secondary coil of the current transformer T1. The first end of the secondary coil of the current transformer T1 is connected to the detection terminal VP of the energy metering chip 1 through the eighth resistor R8. The second end of the secondary coil of the current transformer T1 is grounded to GND. The grounding terminal G of the energy metering chip 1 is grounded to GND. A capacitor C1 is connected between the detection terminal VP and the grounding terminal G of the energy metering chip 1. The output terminal UART of the energy metering chip 1 is connected to the control module 2. The energy metering branch also includes a fifth resistor R5 connected between the first end of the primary coil of the current transformer T1 and the first acquisition terminal a1, and / or a sixth resistor R6 connected between the second end of the primary coil of the current transformer T1 and the second acquisition terminal a2. The control module 2 is connected to the control terminal of the first relay K1 and the control terminal of the second relay K2, respectively. The charging pile also includes a charging and discharging relay group, which is connected between the input and output terminals of the charging pile. The control module is connected to the control terminal of the charging and discharging relay group.

[0089] There are multiple ways to set up the specific structure of a charging pile. The following is a detailed explanation of the process of determining the output terminal resistance using one of these methods as an example. In this embodiment, the main circuit resistance includes both a first resistor R1 and a second resistor R2, the short-circuit detection branch includes both a third resistor R3 and a fourth resistor R4, the detection relay group includes both a first relay K1 and a second relay K2, and the energy metering branch includes both a fifth resistor R5 and a sixth resistor R6.

[0090] Methods for detecting short circuits in the charging pile output include:

[0091] S111: Obtain the current on the power metering branch under the first operating condition of the charging pile.

[0092] S121: Obtain the current on the power metering branch under the second operating condition of the charging pile.

[0093] S131: Calculate the branch voltage based on the current and resistance of the power metering branch under the second operating condition; wherein, the branch voltage is the sum of the voltage across the short-circuit detection branch and the voltage across the resistor at the output end of the charging pile.

[0094] Under the second operating condition, the voltage across the energy metering branch is calculated based on the current and resistance in the energy metering branch. Since the energy metering branch and the short-circuit detection branch are connected in parallel, the voltage across the energy metering branch is equal to the branch voltage.

[0095] Optionally, the branch voltage Up2 can be calculated based on the voltage Us2 at the detection terminal of the power metering chip 1 under the second operating condition, the seventh resistor R7, and the resistance between the first acquisition terminal a1 and the second acquisition terminal a2.

[0096] Under the second operating condition, the current Is2 on the secondary winding of the current transformer T1 is calculated based on the voltage Us2 at the detection terminal of the power metering chip 1 and the seventh resistor R7. Is2 = Us2 / Rs, where Rs is the resistance value of the seventh resistor R7.

[0097] In the second operating condition, the current Ip2 on the primary winding of current transformer T1 is calculated based on the current Is2 on the secondary winding of current transformer T1 and the turns ratio of the primary and secondary windings of current transformer T1. In this embodiment, the current transformer is a precision current transformer, and the turns ratio of the primary and secondary windings of current transformer T1 is set to 1:1. Therefore, the current Is2 on the secondary winding is equal to the current Ip2 on the primary winding. Ip2 = Is2 = Us2 / Rs.

[0098] Calculate the branch voltage Up2 based on the current Ip2 on the primary winding of current transformer T1 under the second operating condition and the resistance between the first acquisition terminal a1 and the second acquisition terminal a2. Branch voltage Up2 =

[0099] Ik2*(RK+Rt)=Ip2*Rp=Us2*Rp / Rs, where Ik2 is the current in the short-circuit detection branch under the second operating condition, Rk is the resistance value of RK' in the short-circuit detection branch, which is the sum of the resistance values ​​of the third resistor R3 and the fourth resistor R4, Rt is the resistance value of Rout at the output terminal of the charging pile under the second operating condition, and Rp is the resistance value of Rp' between the first acquisition terminal a1 and the second acquisition terminal a2. The resistance Rp' between the first acquisition terminal a1 and the second acquisition terminal a2 is the equivalent resistance of the fifth resistor R5 and the sixth resistor R6, and Rp is equal to the sum of the resistance values ​​of the fifth resistor R5 and the sixth resistor R6.

[0100] S141: Calculate the current in the short-circuit detection branch under the second operating condition based on the current in the energy metering branch under the second operating condition, the current in the energy metering branch under the first operating condition, the main circuit resistance, the resistance in the energy metering branch, and the resistance in the short-circuit detection branch.

[0101] Based on the voltage Us2 at the detection terminal of the energy metering chip 1 and the seventh resistor R7 under the second operating condition, calculate the current Ip2 on the primary winding of the current transformer T1 under the second operating condition. Ip2 = Is2 = Us2 / Rs.

[0102] Based on the voltage Us2 at the detection terminal of the power metering chip 1 under the second operating condition, the voltage Us1 at the detection terminal of the power metering chip 1 under the first operating condition, the main circuit resistance Rin', the seventh resistance R7, and the resistance Rp' between the first acquisition terminal a1 and the second acquisition terminal a2, calculate the current Iin2 on the main circuit resistance Rin' under the second operating condition.

[0103] Based on the voltage at the charging pile input terminal, the branch voltage under the second operating condition, and the main circuit resistance Rin'

[0104] Based on the relationship between the two resistors, the current Iin2 across the main circuit resistor Rin' under the second operating condition can be calculated. Alternatively, based on the voltage Us1 at the detection terminal of the energy metering chip 1 under the first operating condition, the seventh resistor R7, the main circuit resistor Rin', and the resistance Rp' between the first acquisition terminal a1 and the second acquisition terminal a2, the input voltage Uin2 of the charging pile under the second operating condition can be calculated. Under the first operating condition, the current Ip1 on the primary winding of the current transformer T1 is Ip1 = Us1 / Rs. Under the first operating condition, the main circuit of the charging pile only contains the main circuit resistor Rin', the fifth resistor R5, and the sixth resistor R6; therefore, the input voltage of the charging pile...

[0105] Uin1 = Iin1*(Rin+Rp) = Us1*(Rin+Rp) / Rs, where, under the first operating condition, the current Iin1 on the main circuit resistor Rin' is Ip1. Before and after the switching of the detection relay group, the voltage at the input terminal of the charging pile remains essentially unchanged. Therefore, under the second operating condition, the voltage at the input terminal of the charging pile is Uin2 = Uin1 = Us1*(Rin+Rp) / Rs.

[0106] Calculate the branch voltage Up2 based on the current Ip2 on the primary winding of the current transformer T1 under the second operating condition and the resistance Rp' between the first acquisition terminal a1 and the second acquisition terminal a2.

[0107] Based on the input voltage Uin2 of the charging pile, the branch voltage Up2, and the main circuit resistance Rin' under the second operating condition, calculate the current Iin2 on the main circuit resistance Rin'.

[0108] Iin2=(Uin2-Up2) / Rin=(Us1*(Rin+Rp) / Rs-Us2*Rp / Rs) / Rin.

[0109] Under the second operating condition, the current Ik2 on the short-circuit detection branch is calculated based on the current Ip2 on the primary winding of current transformer T1 and the current Iin2 on the main circuit resistor Rin'. Ik2 = Iin2 - Ip2.

[0110] S151: Under the second operating condition, calculate the resistance value of the charging pile output terminal Rout' based on the branch voltage Up2 and the current Ik2 on the short-circuit detection branch.

[0111] Rk+Rt=Up2 / Ik2=Up2 / (Iin2-Ip2)=(Us2*Rp / Rs) / [(Us1*(Rin+Rp) / Rs-Us2*Rp / Rs) / Rin-Us2 / Rs]

[0112] From the above formula, we can deduce that the resistance value of the charging pile output terminal Rout' satisfies: Rt=(Us2*Rp / Rs) / [(Us1*(Rin+Rp) / Rs-Us2*Rp / Rs) / Rin-Us2 / Rs]-Rk.

[0113] S161: When the resistance value at the output terminal of the charging pile is less than the set resistance threshold, it is determined that the output terminal of the charging pile is short-circuited.

[0114] S171: After determining that the output terminal of the charging pile is short-circuited and a charging command is received, the charging and discharging relay group is controlled to disconnect.

[0115] The above embodiments exemplify that the main circuit resistance includes a first resistor R1 and a second resistor R2, the short circuit detection branch includes a third resistor R3 and a fourth resistor R4, the detection relay group includes a first relay K1 and a second relay K2, and the power metering branch includes a fifth resistor R5 and a sixth resistor R6, but this is not intended to limit the present invention. In other embodiments, when the main circuit resistance includes only the first resistor R1, the resistance value of the main circuit resistance is equal to the resistance value of the first resistor R1; when the main circuit resistance includes only the second resistor R2, the resistance value of the main circuit resistance is equal to the resistance value of the second resistor R2; when the short circuit detection branch includes only the third resistor R3, the resistance value of the resistor in the short circuit detection branch is equal to the resistance value of the third resistor R3; when the short circuit detection branch includes only the fourth resistor R4, the resistance value of the resistor in the short circuit detection branch is equal to the resistance value of the fourth resistor R4; when the first acquisition terminal a1 and the second acquisition terminal a2 are connected only to the fifth resistor R5, the resistance value between the first acquisition terminal a1 and the second acquisition terminal a2 is equal to the resistance value of the fifth resistor R5; when the first acquisition terminal a1 and the second acquisition terminal a2 are connected only to the sixth resistor R6, the resistance value between the first acquisition terminal a1 and the second acquisition terminal a2 is equal to the resistance value of the sixth resistor R6. The method for determining the resistance value of the output terminal resistance of the charging pile is similar to the above embodiments and will not be repeated here.

[0116] It should be understood that the various forms of processes shown above can be used, with steps reordered, added, or deleted. For example, the steps described in this invention can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution of this invention can be achieved, and this is not limited herein.

[0117] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A charging pile, characterized in that, include: Main circuit resistance, short circuit detection branch, power metering branch, and control module; The first end of the main circuit resistor is connected to the input end of the charging pile; The short-circuit detection branch is connected to the output terminal of the charging pile; The power metering branch is connected to the second terminal of the main circuit resistor and the short circuit detection branch, respectively. The control module is connected to the power metering branch and is used to acquire the current in the power metering branch; The short-circuit detection branch includes a detection relay group, and the control module is connected to the control terminal of the detection relay group; The control module is used to acquire the current on the power metering branch under the first operating condition of the charging pile and the current on the power metering branch under the second operating condition of the charging pile; it is also used to calculate the branch voltage based on the current on the power metering branch under the second operating condition and the resistance on the power metering branch; wherein the branch voltage is the sum of the voltage across the short-circuit detection branch and the voltage across the resistor at the output terminal of the charging pile; to calculate the current on the short-circuit detection branch under the second operating condition based on the current on the power metering branch under the second operating condition, the current on the power metering branch under the first operating condition, the main circuit resistance, the resistance on the power metering branch, and the resistance on the short-circuit detection branch; and, under the second operating condition, to calculate the resistance at the output terminal of the charging pile based on the branch voltage and the current on the short-circuit detection branch, and to determine that the output terminal of the charging pile is short-circuited when the resistance at the output terminal of the charging pile is less than a set resistance threshold; wherein, under the first operating condition, the detection relay group is open, and under the second operating condition, the detection relay group is closed.

2. The charging pile according to claim 1, characterized in that, The charging pile has an input terminal including a first input terminal and a second input terminal, and an output terminal including a first output terminal and a second output terminal; the power metering branch includes a first acquisition terminal and a second acquisition terminal. The main circuit resistor includes a first resistor connected between the first input terminal and the first acquisition terminal, and / or a second resistor connected between the second input terminal and the second acquisition terminal; The detection relay group includes a first relay connected between the first output terminal and the first acquisition terminal, and / or a second relay connected between the second output terminal and the second acquisition terminal; The short-circuit detection branch further includes a third resistor connected between the first output terminal and the first acquisition terminal, and / or a fourth resistor connected between the second output terminal and the second acquisition terminal; The energy metering branch includes a current transformer, a seventh resistor, and an energy metering chip. The first end of the primary coil of the current transformer is connected to the first acquisition terminal, and the second end of the primary coil is connected to the second acquisition terminal. The first end of the seventh resistor is connected to the first end of the secondary coil of the current transformer, and the second end of the seventh resistor is connected to the second end of the secondary coil of the current transformer. The first end of the secondary coil of the current transformer is also connected to the detection terminal of the energy metering chip. The output terminal of the energy metering chip is connected to the control module. The energy metering branch also includes a fifth resistor connected between the first end of the primary coil of the current transformer and the first acquisition terminal, and / or a sixth resistor connected between the second end of the primary coil of the current transformer and the second acquisition terminal. The control module is connected to the control terminal of the first relay and the control terminal of the second relay, respectively.

3. The charging pile according to claim 1, characterized in that, It also includes a charge and discharge relay group, which is connected between the input and output terminals of the charging pile; The control module is connected to the control terminal of the charging and discharging relay group. The control module is used to control the charging and discharging relay group to disconnect when it determines that the output terminal of the charging pile is short-circuited and a charging command is received.

4. A method for detecting a short circuit in the output of a charging pile, characterized in that, Applied to the charging pile according to any one of claims 1-3, the method for detecting a short circuit at the output of the charging pile is executed by the control module; The method for detecting short circuits in the charging pile output includes: The current on the power metering branch of the charging pile is obtained under the first operating condition; under the first operating condition, the detection relay group is disconnected; The current on the power metering branch of the charging pile is obtained under the second operating condition; under the second operating condition, the detection relay group is closed; The resistance value at the output terminal of the charging pile is calculated based on the current in the power metering branch under the first operating condition, the current in the power metering branch under the second operating condition, the main circuit resistance, the resistance in the power metering branch, and the resistance in the short circuit detection branch. When the resistance at the output terminal of the charging pile is less than a set resistance threshold, it is determined that the output terminal of the charging pile is short-circuited.

5. The method for detecting a short circuit at the output of a charging pile according to claim 4, comprising calculating the resistance value at the output terminal of the charging pile based on the current in the energy metering branch under the first operating condition, the current in the energy metering branch under the second operating condition, the main circuit resistance, the resistance in the energy metering branch, and the resistance in the short circuit detection branch, including: The branch voltage is calculated based on the current and resistance on the power metering branch under the second operating condition; wherein the branch voltage is the sum of the voltage across the short-circuit detection branch and the voltage across the resistor at the output terminal of the charging pile. The current in the short-circuit detection branch under the second operating condition is calculated based on the current in the power metering branch under the second operating condition, the current in the power metering branch under the first operating condition, the main circuit resistance, the resistance in the power metering branch, and the resistance in the short-circuit detection branch. Under the second operating condition, the resistance value of the charging pile output terminal is calculated based on the branch voltage and the current in the short-circuit detection branch.

6. The method for detecting a short circuit at the output of a charging pile according to claim 5, characterized in that, The charging pile has an input terminal including a first input terminal and a second input terminal, and an output terminal including a first output terminal and a second output terminal; the power metering branch includes a first acquisition terminal and a second acquisition terminal, and the main circuit resistor includes a first resistor connected between the first input terminal and the first acquisition terminal, and / or a second resistor connected between the second input terminal and the second acquisition terminal; the detection relay group includes a first relay connected between the first output terminal and the first acquisition terminal, and / or a second relay connected between the second output terminal and the second acquisition terminal; the short circuit detection branch further includes a third resistor connected between the first output terminal and the first acquisition terminal, and / or a fourth resistor connected between the second output terminal and the second acquisition terminal; the power metering branch includes a current transformer, a seventh resistor, and a power metering chip. The first end of the primary coil of the current transformer is connected to the first acquisition terminal, and the second end of the primary coil of the current transformer is connected to the second acquisition terminal. The first end of the seventh resistor is connected to the first end of the secondary coil of the current transformer, and the second end of the seventh resistor is connected to the second end of the secondary coil of the current transformer. The first end of the secondary coil of the current transformer is also connected to the detection terminal of the energy metering chip. The output terminal of the energy metering chip is connected to the control module. The energy metering branch also includes a fifth resistor connected between the first end of the primary coil of the current transformer and the first acquisition terminal, and / or a sixth resistor connected between the second end of the primary coil of the current transformer and the second acquisition terminal. The control module is connected to the control terminal of the first relay and the control terminal of the second relay, respectively. Based on the current and resistance of the energy metering branch under the second operating condition, the branch voltage is calculated, including: The branch voltage is calculated based on the voltage at the detection terminal of the power metering chip under the second operating condition, the seventh resistor, and the resistance between the first acquisition terminal and the second acquisition terminal.

7. The method for detecting a short circuit at the output of a charging pile according to claim 6, characterized in that, The branch voltage is calculated based on the voltage at the detection terminal of the energy metering chip under the second operating condition, the seventh resistor, and the resistance between the first and second acquisition terminals, including: Under the second operating condition, the current on the secondary coil of the current transformer is calculated based on the voltage at the detection terminal of the power metering chip and the seventh resistor. Under the second operating condition, the current on the primary winding of the current transformer is calculated based on the current on the secondary winding of the current transformer and the turns ratio of the primary winding and the secondary winding of the current transformer. The branch voltage is calculated based on the current on the primary winding of the current transformer under the second operating condition and the resistance between the first acquisition terminal and the second acquisition terminal.

8. The method for detecting a short circuit at the output of a charging pile according to claim 6, characterized in that, Based on the current in the power metering branch under the second operating condition, the current in the power metering branch under the first operating condition, the main circuit resistance, the resistance in the power metering branch, and the resistance in the short-circuit detection branch, the current in the short-circuit detection branch under the second operating condition is calculated, including: Based on the voltage at the detection terminal of the energy metering chip under the second operating condition and the seventh resistor, calculate the current on the primary coil of the current transformer under the second operating condition. The current in the main circuit resistor under the second operating condition is calculated based on the voltage at the detection terminal of the power metering chip under the second operating condition, the voltage at the detection terminal of the power metering chip under the first operating condition, the main circuit resistor, the seventh resistor, and the resistance between the first acquisition terminal and the second acquisition terminal. Under the second operating condition, the current on the short-circuit detection branch is calculated based on the current on the primary winding of the current transformer and the current on the main circuit resistor.

9. The method for detecting a short circuit at the output of a charging pile according to claim 8, characterized in that, Based on the voltage at the detection terminal of the energy metering chip under the second operating condition, the voltage at the detection terminal of the energy metering chip under the first operating condition, the main circuit resistance, the seventh resistor, and the resistance between the first acquisition terminal and the second acquisition terminal, the current in the main circuit resistance under the second operating condition is calculated, including: Based on the voltage at the detection end of the power metering chip under the first operating condition, the seventh resistor, the main circuit resistor, and the resistance between the first acquisition end and the second acquisition end, the voltage at the input end of the charging pile under the second operating condition is calculated. The branch voltage is calculated based on the current on the primary winding of the current transformer under the second operating condition and the resistance between the first and second acquisition terminals. The current in the main circuit resistor is calculated based on the voltage at the input terminal of the charging pile, the branch voltage, and the main circuit resistance under the second operating condition.

10. The method for detecting a short circuit at the output of a charging pile according to claim 4, characterized in that, The charging pile also includes a charging and discharging relay group, which is connected between the input and output terminals of the charging pile, and the control module is connected to the control terminal of the charging and discharging relay group. After determining that the output terminal of the charging pile is short-circuited and receiving a charging command, the charging and discharging relay group is controlled to disconnect.

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