A DC charging pile main circuit contact adhesion detection circuit

Abstract

This utility model relates to a contact adhesion detection circuit for the main circuit of a DC charging pile, belonging to the field of new energy charging piles. It includes a charging pile control unit and a detection unit. The charging pile control unit includes a power port and two main contacts connected to the power port. The charging pile control unit is used to set the state of the two main contacts. A detection circuit is provided between the two main contacts. The detection circuit includes a detection power supply, a control switch, and a level detection module. The detection power supply is connected to the two main contacts. The control switch and the level detection module are alternately installed on the two main contacts. The detection unit drives the control switch, and together with the charging pile control unit, they jointly realize the detection of contact adhesion.

Description

Technical Field

[0001] This utility model relates to the field of new energy charging piles, specifically to a DC charging pile main circuit contact adhesion detection circuit. Background Technology

[0002] There is a fault and risk of sticking between the main contacts of the two high-voltage DC contactors on the positive and negative terminals of the main circuit of the DC charging pile. This fault needs to be detected in time and reported to the charging pile control unit to stop charging and ensure the safe operation of the charging pile.

[0003] Traditional detection methods rely on the status of auxiliary contacts linked to the main contacts to determine if the main contacts are stuck. However, this method has a drawback: when a DC high-voltage contactor operates at high internal temperatures, the plastic part of the microswitch acting as the auxiliary contact softens, resulting in abnormal elasticity and abnormal linkage. This abnormal linkage between the auxiliary and main contacts means that when the DC contactor is disconnected, no voltage is detected at the downstream end of the contact. However, this does not necessarily mean that there is no contact sticking, because if one positive and one negative contact are stuck while the other is disconnected, no voltage will be detected at the downstream end, leading to a misjudgment of main contact sticking.

[0004] There is an urgent need for a new detection circuit to address the aforementioned false positive scenarios and improve accuracy. Utility Model Content

[0005] To address the shortcomings of the existing technology, this utility model provides a DC charging pile main circuit contact adhesion detection circuit. It adopts a method of alternating detection of positive and negative contactor contacts, which can realize the detection of adhesion of any contact and has a simple circuit, high reliability, and accurate detection.

[0006] The technical solution of this utility model is as follows: A DC charging pile main circuit contact adhesion detection circuit includes a charging pile control unit and a detection unit. The charging pile control unit includes a power port and two main contacts connected to the power port. The charging pile control unit is used to set the state of the two main contacts. A detection circuit is provided between the two main contacts. The detection circuit includes a detection power supply, a control switch, and a level detection module. The detection power supply is connected to the two main contacts. The control switch and the level detection module are respectively alternately installed on the two main contacts. The detection unit drives the control switch, and together with the charging pile control unit, realizes the detection of main contact adhesion.

[0007] As a preferred embodiment, the main contact includes a second contact C1, which is the main contact of the positive high-voltage DC contactor.

[0008] As a preferred embodiment, the control switch includes a second relay K2, and the level detection module includes: a second detection optocoupler U2, a level detection port B connected in parallel to one side of the second detection optocoupler U2, and a ground terminal connected in parallel to the other side of the second detection optocoupler U2. The positive terminal of the detection power supply is connected in sequence to the second contact C1 and the second relay K2, and the second relay K2 is connected to the second detection optocoupler U2. The second detection optocoupler U2 outputs a low level at one side to indicate that the second contact is stuck; otherwise, the second contact is normal.

[0009] As a preferred embodiment, the main contact includes a first contact C2, which is the main contact of the negative high-voltage DC contactor.

[0010] As a preferred embodiment, the control switch includes a first relay K1, and the level detection module includes: a first detection optocoupler U1, a level detection port A connected in parallel to one side of the first detection optocoupler U1, and a ground terminal connected in parallel to the other side of the first detection optocoupler U1. The positive terminal of the detection power supply is connected to the first relay K1, the first relay K1 is connected to the first detection optocoupler U1, and the other side of the first detection optocoupler U1 is also connected to a first contact C2. The level detection port on one side of the first detection optocoupler U1 outputs a low level to indicate that the first contact is stuck; otherwise, the first contact is normal.

[0011] As a preferred embodiment, a current-limiting resistor R1 is provided between the detection power supply and the first detection optocoupler U1. The current-limiting resistor R1 is used to match the input power of the first detection optocoupler U1.

[0012] As a preferred embodiment, the detection unit is connected to the charging pile control unit, and the detection unit is used to report the status of the main contact to the charging pile control unit.

[0013] Furthermore, the charging pile control unit is used to drive and control the disconnection control switch to complete the detection.

[0014] Furthermore, the detection optocoupler U1 and detection optocoupler U2 include a first primary side and a second primary side for input, and a first secondary side and a second secondary side for output. The first primary side is connected to a control switch, the second primary side is connected to a level detection port, the first secondary side is grounded, and the second secondary side is connected to the negative terminal of the detection power supply.

[0015] The advantages of this utility model based on the above solution are as follows: In this invention, the detection power supply, control switch, and level detection module each form a circuit corresponding to each contact, such that each control switch corresponds to the adhesion state of the detection contact. That is, the control switch and level detection module are alternately arranged on several contacts, such as two. When the contacts are normal and not adhesion, the circuit is not conductive, and the level detection module outputs a high level; when adhesion occurs, the circuit is conductive, and the level detection module outputs a low level. With the detection circuit and a suitable detection unit, remote and rapid detection of contacts can be achieved. It can detect adhesion of any contact, such as detecting adhesion faults of the main contacts of a positive high-voltage DC contactor or the main contacts of a negative high-voltage DC contactor. Moreover, the circuit is simple, highly reliable, and accurate in detection. Attached Figure Description

[0016] Figure 1 This is a circuit diagram of a DC charging pile main circuit contact adhesion detection circuit according to the present invention. Detailed Implementation

[0017] To better understand the purpose, technical solution, and technical effects of this utility model, the following description, in conjunction with the accompanying drawings and embodiments, will provide further explanation. It should be noted that similar reference numerals and letters in the following drawings indicate similar items; therefore, once an item is defined in one drawing, it does not need further definition and explanation in subsequent drawings. It is also stated that the embodiments described below are only for explaining this utility model and are not intended to limit it.

[0018] It should be noted that when a component is referred to as "fixed to" or "set on" another component, it can be directly on the other component or there may be an intermediate component. When a component is referred to as "connected to" another component, it can be directly connected to the other component or there may be an intermediate component.

[0019] The indicated orientation or positional relationship is based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product is usually placed when in use, or the orientation or positional relationship in which a person skilled in the art would normally understand it, or the orientation or positional relationship in which the product is usually placed when in use. It is only for the purpose of facilitating the description of this application and simplifying the description, and is not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. Example 1

[0020] like Figure 1As shown, a specific implementation scheme of a DC charging pile main circuit contact adhesion detection circuit is presented. It aims to solve the problems of single contact adhesion not being identified, auxiliary contact linkage misjudgment, and detection circuit interference with the charging system in traditional detection methods. It is applicable to the main circuit of new energy DC charging piles and can accurately detect single or double point adhesion faults of the main contacts of the positive and negative high voltage DC contactors. Moreover, the circuit structure is simple and highly reliable.

[0021] The DC charging pile main circuit DC contactor contact adhesion detection circuit includes a charging pile control unit and a detection unit. The charging pile control unit includes a power port and two main contacts connected to the power port. The charging pile control unit is used to set the state of the two main contacts. A detection circuit is provided between the two main contacts. The detection circuit includes a detection power supply, a control switch, and a level detection module. The detection power supply is connected to the two main contacts. The control switch and the level detection module are respectively installed alternately on the two main contacts. The detection unit drives the control switch, and together with the charging pile control unit, realizes the detection of main contact adhesion. The detection power supply is also the charging module shown on the left side of the figure.

[0022] In one application scenario, the main circuit includes a charging pile control unit with an output voltage range of 200-1000Vdc, and the function of transmitting the output voltage to the output terminal of the charging pile. The output terminal and the main circuit include the main contacts of at least two DC contactors.

[0023] The main contacts include a second contact C1 and a first contact C2. The first contact C2 is the main contact of the negative high-voltage DC contactor, and the second contact C1 is the main contact of the positive high-voltage DC contactor. In practice, one end of the second contact C1 is connected to the positive output terminal of the detection power supply, and the other end is connected to the positive output terminal of the charging pile, which is used to control the on / off state of the positive terminal of the main circuit. One end of the first contact C2 is connected to the negative output terminal of the detection power supply, and the other end is connected to the negative output terminal of the charging pile, which is used to control the on / off state of the negative terminal of the main circuit. Two parallel detection circuits are provided corresponding to the main contacts, respectively for detecting adhesion at the first contact C2 and the second contact C1. Each circuit is equipped with positive and negative terminals of the detection power supply, a current-limiting resistor, a control switch, and a detection optocoupler. The two circuits are staggered to achieve single-point adhesion detection, as detailed below: The detection circuit corresponding to the first contact C2 includes a current-limiting resistor R1, a relay K1, and a detection optocoupler U1. Specifically, one end of the current-limiting resistor R1 is connected to the positive output terminal of the detection power supply, and the other end is connected to the normally open contact of the detection control relay K1. Its function is to limit the current in the detection circuit and match the current transfer ratio of the detection optocoupler U1 to prevent overcurrent damage to the optocoupler. Two to four resistors can be connected in series and parallel depending on the voltage range of the detection power supply. The relay K1 is a normally open relay; its coil is connected to the drive port of the charging pile control unit, and one end of its normally open contact is connected to the current-limiting resistor R1, while the other end is connected to the primary positive terminal of the detection optocoupler U1. Its state is determined by… The charging pile control unit closes the circuit only during the detection period and opens it outside the detection period to exit the detection circuit. The detection optocoupler U1 uses a 4-interface opto-isolation device, divided into a primary side on the input side and a secondary side on the output side. The primary side includes: the positive terminal is connected to the normally open contact of relay K1, and the negative terminal is connected to the detection power supply terminal of the first contact C2, that is, the end of the first contact C2 closest to the negative terminal of the detection power supply. The secondary side includes: the positive terminal is connected to the signal input terminal of the level detection port A corresponding to the detection unit, and the negative terminal is connected to the circuit ground. The optocoupler realizes the electrical isolation between the high-voltage detection circuit and the low-voltage control / detection circuit to prevent high-voltage signals from damaging the detection unit or the charging pile control unit.

[0024] The detection circuit corresponding to the second contact C1 includes a current-limiting resistor R2, a detection control relay K2, and a detection optocoupler U2, used to detect whether the second contact C1 is stuck. The connection relationship of the components is staggered with the detection circuit of the first contact C2. One end of the current-limiting resistor R2 is connected to the normally open contact of the detection control relay K2, and the other end is connected to the positive terminal of the primary side of the detection optocoupler U2. The selection principle is the same as that of the current-limiting resistor R1, and it is adapted to the current transmission ratio between the output voltage of the charging pile control unit and the current of the detection optocoupler U2. The detection control relay K2 is a normally open relay. The coil end is connected to the drive port of the charging pile control unit. One end of the normally open contact is connected to the current limiting resistor R2, and the other end is connected to the charging pile output side terminal of the second contact C1, that is, the end of the second contact C1 that is closer to the charging pile output end. It is synchronously controlled with relay K1 and closes only during the detection period. The detection optocoupler U2 is also a 4-interface opto-isolated device with a clear division of labor between the primary and secondary sides: Primary side: the positive terminal is connected to the current-limiting resistor R2, and the negative terminal is connected to the negative output terminal of the detection power supply; Secondary side: the positive terminal is connected to the level detection port B and connected to the signal input terminal of the detection unit, and the negative terminal is connected to the circuit ground.

[0025] To achieve remote automated detection, this invention also includes a reporting unit corresponding to the charging pile control unit and the detection unit. The reporting unit is a built-in functional module of the detection unit. It transmits the detection data from the detection unit to the charging pile control unit via network or wired connection. The charging pile control unit is used to drive the opening and closing states of the first contact C2 and the second contact C1, drive the on / off states of relays K1 and K2, and receive reported fault information. When a sticking fault is detected, the charging pile control unit immediately stops the relevant charging process. The detection unit is used for signal acquisition and judgment. It connects to level detection port A and level detection port B, collects the level states of the two points in real time, converts the level conversion signal into a sticking fault signal, and transmits the data to the charging pile control unit through the reporting unit to achieve fault identification.

[0026] One possible testing procedure is: To prevent the fault from escalating during the initial charging phase, the detection process is divided into: pre-processing - single-point detection - dual-point judgment - detection completion. Preparation: The charging pile control unit first sends a disconnect command to the first contact C2 and the second contact C1 to ensure that they are in the disconnected state. If the contacts are stuck together, they are physically stuck together and cannot be actually disconnected. At the same time, relays K1 and K2 are in the initial disconnected state, and the detection circuit is not started. Since the secondary side of the detection optocoupler is not conducting, the level detection port A and level detection port B output a high level by default. First single-point detection: detection of adhesion of negative main contact or first contact C2. At this time, the charging pile control unit sends a closing command to relay K1, and the first detection circuit is connected. The path includes: detection power positive terminal, current limiting resistor R1, relay K1, detection optocoupler U1 primary positive terminal, detection optocoupler U1 primary negative terminal, first contact C2, detection power negative terminal. If the first contact C2 is not stuck and the contact is normally disconnected, then the first detection circuit is open, there is no current on the primary side of the detection optocoupler U1, and the secondary side is not conducting → point A maintains a high level → the first contact C2 is determined to be normal; If the first contact C2 is stuck and the contact is not disconnected: the first detection circuit is open, the primary side of the detection optocoupler U1 is energized and emits light, and the secondary side is photosensitive and conducts → point A changes from high level to low level → it is determined that the first contact C2 is stuck, and the detection unit immediately reports the first contact C2 stuck fault to the charging pile control unit.

[0027] Second single-point detection: The charging pile control unit first sends a disconnect command to relay K1 to close the first detection circuit; then sends a close command to K2 to connect the second detection circuit. The path includes positive terminal of detection power supply → second contact C1 → relay K2 → current limiting resistor R2 → primary positive terminal of detection optocoupler U2 → primary negative terminal of detection optocoupler U2 → negative terminal of detection power supply. The detection unit acquires the voltage level at point B, and the determination logic is as follows: If the second contact C1 is not stuck, the contact is normally open: the second detection circuit is open, there is no current on the primary side of U2, and the secondary side is not conducting → point B maintains a high level → the second contact C1 is judged to be normal. If the second contact C1 is stuck and the contact is not disconnected: the second detection circuit is open, the primary side of the detection optocoupler U2 is energized and emits light, and the secondary side is photosensitive and conducts → point B changes from high level to low level → it is determined that the second contact C1 is stuck, and the detection unit reports the second contact C1 stuck fault to the charging pile control unit.

[0028] In the two-point detection, if both points A and B change from high level to low level during the above two detection steps (i.e., both the first contact C2 and the second contact C1 meet the adhesion judgment condition), the detection unit determines that the second contact C1 and the first contact C2 are simultaneously adhered, and reports the dual-contact adhesion fault to the charging pile control unit.

[0029] Detection completion: Exit the detection loop and execute subsequent actions.

[0030] The charging pile control unit sends a disconnect command to relay K2 to shut down the second detection circuit. At this time, the detection circuit is completely separated from the main circuit to avoid interference with the subsequent charging process. If no fault is detected and points A and B remain at a high level: the charging pile control unit sends a closing command to the second contact C1 and the first contact C2, the main circuit is turned on, and the charging pile enters the normal charging state; If a single or double point of contact adhesion is detected: the charging pile control unit immediately prevents the second contact C1 and the first contact C2 from closing, stops the charging process, and prompts a contactor adhesion fault through the existing common human-machine interface, waiting for maintenance.

[0031] In this invention, the detection power supply, control switch, and level detection module each form a circuit corresponding to each contact, such that each control switch corresponds to the adhesion state of the detection contact. That is, the control switch and level detection module are alternately arranged on several contacts, such as two. When the contacts are normal and not adhesion, the circuit is not conductive, and the level detection module outputs a high level; when adhesion occurs, the circuit is conductive, and the level detection module outputs a low level. With the detection circuit and a suitable detection unit, remote and rapid detection of contacts can be achieved. It can detect adhesion of any contact, such as detecting adhesion faults of the main contacts of a positive high-voltage DC contactor or the main contacts of a negative high-voltage DC contactor. Moreover, the circuit is simple, highly reliable, and accurate in detection.

[0032] 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.

[0033] The above embodiments only illustrate several implementation methods of this utility model, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the utility model patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this utility model, and these all fall within the protection scope of this utility model. Therefore, the protection scope of this utility model patent should be determined by the appended claims.

Claims

1. A detection circuit for contact adhesion in the main circuit of a DC charging pile, characterized in that, It includes a charging pile control unit and a detection unit. The charging pile control unit includes a power port and two main contacts connected to the power port. The charging pile control unit is used to set the status of the two main contacts. A detection circuit is provided between the two main contacts. The detection circuit includes a detection power supply, a control switch, and a level detection module. The detection power supply is connected to the two main contacts. The control switch and the level detection module are installed alternately on the two main contacts. The detection unit drives the control switch and works together with the charging pile control unit to detect the adhesion of the main contacts.

2. The DC charging pile main circuit contact adhesion detection circuit according to claim 1, characterized in that, The main contacts include the second contact C1, which is the main contact of the positive high voltage DC contactor.

3. The DC charging pile main circuit contact adhesion detection circuit according to claim 2, characterized in that, The control switch includes a second relay K2. The level detection module includes a second detection optocoupler U2, a level detection port B connected in parallel to one side of the second detection optocoupler U2, and a ground terminal connected in parallel to the other side of the second detection optocoupler U2. The positive terminal of the detection power supply is connected to the second contact C1 and the second relay K2 in sequence. The second relay K2 is connected to the second detection optocoupler U2. The second detection optocoupler U2 outputs a low level at one side to indicate that the second contact is stuck; otherwise, the second contact is normal.

4. The DC charging pile main circuit contact adhesion detection circuit according to claim 3, characterized in that, The main contacts include the first contact C2, which is the main contact of the negative high voltage DC contactor.

5. The DC charging pile main circuit contact adhesion detection circuit according to claim 4, characterized in that, The control switch includes a first relay K1. The level detection module includes a first detection optocoupler U1, a level detection port A connected in parallel to one side of the first detection optocoupler U1, and a ground terminal connected in parallel to the other side of the first detection optocoupler U1. The positive terminal of the detection power supply is connected to the first relay K1. The first relay K1 is connected to the first detection optocoupler U1. The other side of the first detection optocoupler U1 is also connected to the first contact C2. The level detection port on one side of the first detection optocoupler U1 outputs a low level to indicate that the first contact is stuck; otherwise, the first contact is normal.

6. The DC charging pile main circuit contact adhesion detection circuit according to claim 5, characterized in that, A current-limiting resistor R1 is provided between the detection power supply and the first detection optocoupler U1. The current-limiting resistor R1 is used to match the input power of the first detection optocoupler U1.

7. The DC charging pile main circuit contact adhesion detection circuit according to claim 5, characterized in that, A current-limiting resistor R2 is provided between the detection power supply and the second detection optocoupler U2. The current-limiting resistor R2 is used to match the input power of the second detection optocoupler U2.

8. The DC charging pile main circuit contact adhesion detection circuit according to claim 1, characterized in that, The detection unit is connected to the charging pile control unit and is used to report the status of the main contact to the charging pile control unit.

9. A DC charging pile main circuit contact adhesion detection circuit according to claim 8, characterized in that, The charging pile control unit is used to drive and control the disconnection switch to complete the detection.

10. A DC charging pile main circuit contact adhesion detection circuit according to claim 5, characterized in that, The detection optocouplers U1 and U2 include a first primary side and a second primary side for input, and a first secondary side and a second secondary side for output. The first primary side is connected to a control switch, the second primary side is connected to a level detection port, the first secondary side is grounded, and the second secondary side is connected to the negative terminal of the detection power supply.

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