Relay sticking detection circuit and alternating current charging pile

Abstract

The application relates to a relay, and particularly provides a relay sticking detection circuit and an alternating current charging pile, aiming to improve the sticking detection reliability and reduce the circuit volume and cost. The circuit provided by the application comprises a sticking detection sub-circuit in the firewire and zero line detection circuits; the first detection end and the first main electrode of the switching tube are respectively connected with the positive and negative electrode input ends of the photoelectric coupler in the sticking detection sub-circuit, the second detection end and the third detection end are respectively connected with the second main electrode and the control electrode of the switching tube, and the signal output end is connected with the output end of the photoelectric coupler; the first detection end and the second detection end are respectively connected with the input ends of the firewire and zero line relays in the firewire detection circuit, and the third detection end is connected with the output end of the firewire relay; the first detection end and the second detection end are respectively connected with the input ends of the zero line and firewire relays in the zero line detection circuit, and the third detection end is connected with the output end of the zero line relay. The above circuit can improve the sticking detection reliability and reduce the circuit volume and cost.

Description

Technical Field

[0001] This application relates to the field of relay technology, specifically to a relay adhesion detection circuit and an AC charging pile. Background Technology

[0002] AC charging stations are crucial equipment for replenishing energy for electric and hybrid vehicles. They contain relays that switch the charging station's operating status (e.g., start charging, stop charging), provide electrical isolation, and offer circuit protection. Clearly, relays are essential for the normal operation of AC charging stations. However, due to factors such as component aging and environmental pollution, the relay contacts may stick together, causing the relay to remain connected and unable to disconnect. This can lead to charging station malfunctions and even endanger the user's safety.

[0003] Currently, there are five main methods for detecting relay sticking.

[0004] The first method is to use a relay with auxiliary contacts. The auxiliary contacts can synchronously feedback the status of the main contacts, but relays with auxiliary contacts are generally large in size and expensive.

[0005] The second method is to detect the current between the live wire and the neutral wire on the output side of the relay through an optocoupler circuit. When the contacts of both the live wire and the neutral wire relays are short-circuited at the same time, a sticking fault can be detected. However, when only the contacts of the live wire relay are sticking, the sticking fault can only be determined by controlling the neutral wire relay to conduct through software, which poses a safety risk.

[0006] The third method involves detecting neutral wire contact faults by adding an isolated power supply and a small relay. Before charging begins, the small relay is closed, creating a circuit through resistors, neutral wire contacts, diodes, optocouplers, and other components on the output side of the neutral wire relay. This allows for the detection of contact sticking faults in the neutral wire relay. However, this method is not only costly and bulky, but it is also only applicable to detecting neutral wire relay sticking; it cannot detect live wire relay sticking, which poses a greater safety risk.

[0007] The fourth method is to detect adhesion faults by using resistor voltage division and isolation voltage acquisition. However, this method requires a large current to detect the resistor, which causes heat generation and power loss. At the same time, the cost of isolation voltage acquisition is relatively high.

[0008] The fifth method is to detect the relay output voltage through a voltage transformer. This method is accurate, but it is bulky, expensive, and not cost-effective.

[0009] Accordingly, a new technical solution is needed in this field to solve the above problems. Summary of the Invention

[0010] In order to overcome the above-mentioned defects, this application is made to provide a low-cost, small-sized relay sticking detection circuit that can reliably detect whether a relay is stuck.

[0011] In a first aspect, a relay adhesion detection circuit is provided, wherein the relay includes a live wire relay and a neutral wire relay respectively disposed on the live wire and the neutral wire in an AC line, and the circuit includes a live wire detection circuit and a neutral wire detection circuit, wherein both the live wire detection circuit and the neutral wire detection circuit include an adhesion detection sub-circuit.

[0012] The adhesion detection sub-circuit includes an optocoupler, a switching transistor, a first detection terminal, a second detection terminal, a third detection terminal, and a signal output terminal. The first detection terminal and the first main electrode of the switching transistor are respectively connected to the positive and negative input terminals of the optocoupler. The second detection terminal and the third detection terminal are respectively connected to the second main electrode and the control electrode of the switching transistor. The signal output terminal is connected to the output terminal of the optocoupler. When the first detection terminal and the third detection terminal are connected and not connected, the signals of the signal output terminal are the first signal and the second signal, respectively.

[0013] In the live wire detection circuit, the first detection terminal of the adhesion detection sub-circuit is connected to the input terminal of the live wire relay, the second detection terminal is connected to the input terminal of the neutral wire relay, and the third detection terminal is connected to the output terminal of the live wire relay.

[0014] In the neutral wire detection circuit, the first detection terminal of the adhesion detection sub-circuit is connected to the input terminal of the neutral wire relay, the second detection terminal is connected to the input terminal of the live wire relay, and the third detection terminal is connected to the output terminal of the neutral wire relay.

[0015] In one technical solution of the above-mentioned relay adhesion detection circuit, the adhesion detection sub-circuit includes a first resistor;

[0016] The signal output terminal is connected to the positive output terminal of the optocoupler, the first end of the first resistor is connected to the power supply, the second end of the first resistor is connected in series between the signal output terminal and the positive output terminal of the optocoupler, and the negative output terminal of the optocoupler is grounded.

[0017] In one technical solution of the above-mentioned relay adhesion detection circuit, the first signal is a square wave voltage signal, and the second signal is a high-level voltage signal;

[0018] The frequency of the square wave voltage signal is the same as the frequency of the alternating current in the alternating current line.

[0019] In one technical solution of the above-mentioned relay adhesion detection circuit, the adhesion detection sub-circuit includes a second resistor;

[0020] The first end of the second resistor is connected to the control electrode of the switching transistor, and the second end of the second resistor is connected to the second main electrode of the switching transistor.

[0021] In one technical solution of the above-mentioned relay adhesion detection circuit, the adhesion detection sub-circuit includes a diode;

[0022] The anode of the diode is connected to the second main electrode of the switching transistor, and the cathode of the diode is connected to the third detection terminal.

[0023] In one technical solution of the above-mentioned relay adhesion detection circuit, the adhesion detection sub-circuit includes a first Zener diode;

[0024] The anode of the first Zener diode is connected to the third detection terminal, and the cathode of the first Zener diode is connected to the control electrode of the switching transistor.

[0025] In one technical solution of the above-mentioned relay adhesion detection circuit, the adhesion detection sub-circuit includes a second Zener diode;

[0026] The anode of the second Zener diode is connected to the first main electrode of the switching transistor, and the cathode of the second Zener diode is connected to the negative input terminal of the optocoupler.

[0027] In one technical solution of the above-mentioned relay adhesion detection circuit, the adhesion detection sub-circuit includes a first current-limiting resistor unit and a second current-limiting resistor unit;

[0028] The first current-limiting resistor unit is connected in series between the first detection terminal and the positive input terminal of the optocoupler, and the first current-limiting resistor unit includes one or more current-limiting resistors connected in series.

[0029] The second current-limiting resistor unit is connected in series between the third detection terminal and the control electrode of the switching transistor, and the second current-limiting resistor unit includes one or more current-limiting resistors connected in series.

[0030] In one technical solution of the above-mentioned relay adhesion detection circuit, the switching transistor is a transistor or a MOSFET.

[0031] In a second aspect, an AC charging station is provided, which includes a live wire relay and a neutral wire relay disposed on the live wire and neutral wire of an AC line, and the AC charging station also includes the relay adhesion detection circuit provided in the first aspect.

[0032] In one technical solution of the aforementioned AC charging pile, the AC charging pile includes a main control circuit, which is configured to:

[0033] The signal output of the adhesion detection sub-circuit in the live wire detection circuit is detected; if the signal is the first signal, it is determined that the live wire relay is stuck; if the signal is the first signal, it is determined that the live wire relay is not stuck.

[0034] The signal output of the adhesion detection sub-circuit in the neutral wire detection circuit is detected; if the signal is the first signal, it is determined that the neutral wire relay is stuck; if the signal is the first signal, it is determined that the neutral wire relay is not stuck.

[0035] Solution 1. A relay adhesion detection circuit, wherein the relay includes a live wire relay and a neutral wire relay respectively disposed on the live wire and the neutral wire in an AC line, characterized in that the circuit includes a live wire detection circuit and a neutral wire detection circuit, and both the live wire detection circuit and the neutral wire detection circuit include an adhesion detection sub-circuit;

[0036] The adhesion detection sub-circuit includes an optocoupler, a switching transistor, a first detection terminal, a second detection terminal, a third detection terminal, and a signal output terminal. The first detection terminal and the first main electrode of the switching transistor are respectively connected to the positive and negative input terminals of the optocoupler. The second detection terminal and the third detection terminal are respectively connected to the second main electrode and the control electrode of the switching transistor. The signal output terminal is connected to the output terminal of the optocoupler. When the first detection terminal and the third detection terminal are connected and not connected, the signals of the signal output terminal are the first signal and the second signal, respectively.

[0037] In the live wire detection circuit, the first detection terminal of the adhesion detection sub-circuit is connected to the input terminal of the live wire relay, the second detection terminal is connected to the input terminal of the neutral wire relay, and the third detection terminal is connected to the output terminal of the live wire relay.

[0038] In the neutral wire detection circuit, the first detection terminal of the adhesion detection sub-circuit is connected to the input terminal of the neutral wire relay, the second detection terminal is connected to the input terminal of the live wire relay, and the third detection terminal is connected to the output terminal of the neutral wire relay.

[0039] Scheme 2. The relay adhesion detection circuit according to Scheme 1, characterized in that the adhesion detection sub-circuit includes a first resistor;

[0040] The signal output terminal is connected to the positive output terminal of the optocoupler, the first end of the first resistor is connected to the power supply, the second end of the first resistor is connected in series between the signal output terminal and the positive output terminal of the optocoupler, and the negative output terminal of the optocoupler is grounded.

[0041] Scheme 3. The relay adhesion detection circuit according to Scheme 2, characterized in that the first signal is a square wave voltage signal and the second signal is a high-level voltage signal;

[0042] The frequency of the square wave voltage signal is the same as the frequency of the alternating current in the alternating current line.

[0043] Solution 4. The relay adhesion detection circuit according to Solution 1, characterized in that the adhesion detection sub-circuit includes a second resistor;

[0044] The first end of the second resistor is connected to the control electrode of the switching transistor, and the second end of the second resistor is connected to the second main electrode of the switching transistor.

[0045] Solution 5. The relay adhesion detection circuit according to Solution 1, characterized in that the adhesion detection sub-circuit includes a diode;

[0046] The anode of the diode is connected to the second main electrode of the switching transistor, and the cathode of the diode is connected to the third detection terminal.

[0047] Solution 6. The relay adhesion detection circuit according to Solution 1, characterized in that the adhesion detection sub-circuit includes a first Zener diode;

[0048] The anode of the first Zener diode is connected to the third detection terminal, and the cathode of the first Zener diode is connected to the control electrode of the switching transistor.

[0049] Solution 7. The relay adhesion detection circuit according to Solution 1, characterized in that the adhesion detection sub-circuit includes a second Zener diode;

[0050] The anode of the second Zener diode is connected to the first main electrode of the switching transistor, and the cathode of the second Zener diode is connected to the negative input terminal of the optocoupler.

[0051] Solution 8. The relay adhesion detection circuit according to Solution 1, characterized in that the adhesion detection sub-circuit includes a first current-limiting resistor unit and a second current-limiting resistor unit;

[0052] The first current-limiting resistor unit is connected in series between the first detection terminal and the positive input terminal of the optocoupler, and the first current-limiting resistor unit includes one or more current-limiting resistors connected in series.

[0053] The second current-limiting resistor unit is connected in series between the third detection terminal and the control electrode of the switching transistor, and the second current-limiting resistor unit includes one or more current-limiting resistors connected in series.

[0054] Solution 9. The relay adhesion detection circuit according to claim 1, wherein the switching transistor is a transistor or a MOSFET.

[0055] Scheme 10. An AC charging pile, the AC charging pile including a live wire relay and a neutral wire relay disposed on the live wire and neutral wire in an AC line, characterized in that the AC charging pile includes a relay adhesion detection circuit as described in any one of Schemes 1 to 9.

[0056] Solution 11. The AC charging pile according to Solution 10, characterized in that the AC charging pile includes a main control circuit, the main control circuit being configured to:

[0057] The signal output of the adhesion detection sub-circuit in the live wire detection circuit is detected; if the signal is the first signal, it is determined that the live wire relay is stuck; if the signal is the first signal, it is determined that the live wire relay is not stuck.

[0058] The signal output of the adhesion detection sub-circuit in the neutral wire detection circuit is detected; if the signal is the first signal, it is determined that the neutral wire relay is stuck; if the signal is the first signal, it is determined that the neutral wire relay is not stuck.

[0059] The above-described technical solutions of this application have at least one or more of the following beneficial effects:

[0060] In one technical solution of the relay adhesion detection circuit provided in this application, the relay includes a live wire relay and a neutral wire relay respectively disposed on the live wire and neutral wire in the AC line. The relay adhesion detection circuit includes a live wire detection circuit and a neutral wire detection circuit, and both the live wire detection circuit and the neutral wire detection circuit include adhesion detection sub-circuit.

[0061] The adhesion detection subcircuit includes an optocoupler, a switching transistor, a first detection terminal, a second detection terminal, a third detection terminal, and a signal output terminal. The first detection terminal and the first main electrode of the switching transistor are connected to the positive and negative input terminals of the optocoupler, respectively. The second and third detection terminals are connected to the second main electrode and the control electrode of the switching transistor, respectively. The signal output terminal is connected to the output terminal of the optocoupler. When the first and third detection terminals are connected and disconnected, the signals at the signal output terminal are the first signal and the second signal, respectively. In the live wire detection circuit, the first detection terminal of the adhesion detection subcircuit is connected to the input terminal of the live wire relay, the second detection terminal is connected to the input terminal of the neutral wire relay, and the third detection terminal is connected to the output terminal of the live wire relay. In the neutral wire detection circuit, the first detection terminal of the adhesion detection subcircuit is connected to the input terminal of the neutral wire relay, the second detection terminal is connected to the input terminal of the live wire relay, and the third detection terminal is connected to the output terminal of the neutral wire relay.

[0062] In the live wire detection circuit, if the first detection terminal is connected to the third detection terminal, it indicates that the input and output terminals of the live wire relay are stuck together; otherwise, they are not stuck. In the neutral wire detection circuit, if the first detection terminal is connected to the third detection terminal, it indicates that the input and output terminals of the neutral wire relay are stuck together; otherwise, they are not stuck. Based on this, the first or second voltage signal output from the signal output terminal can be used to accurately detect whether the live wire relay and the neutral wire relay are stuck together. Furthermore, compared to existing technologies, the above circuit structure does not require the use of relays with auxiliary contacts, isolated power supplies, miniature relays, or voltage transformers, resulting in smaller size and lower cost. Additionally, compared to existing technologies, the above circuit structure does not require manual closing of the relays, avoiding the risk of electric shock and providing higher safety.

[0063] In one technical solution for implementing the AC charging pile provided in this application, the AC charging pile includes a live wire relay and a neutral wire relay installed on the live wire and neutral wire of the AC line. The AC charging pile also includes the relay sticking detection circuit described in the above technical solution. Based on this, before charging the load using the AC charging pile, the relay sticking detection circuit can accurately detect whether the live wire relay and the neutral wire relay are stuck together. Only when neither is stuck can the load be charged, thereby ensuring the safety of load charging. Attached Figure Description

[0064] The disclosure of this application will become more readily understood with reference to the accompanying drawings. It will be readily understood by those skilled in the art that these drawings are for illustrative purposes only and are not intended to limit the scope of protection of this application. Wherein:

[0065] Figure 1 This is a schematic diagram of the connection between a live wire relay and a neutral wire relay according to an embodiment of this application;

[0066] Figure 2 This is a schematic diagram of a relay adhesion detection circuit according to an embodiment of this application;

[0067] Figure 3 This is a schematic diagram of an adhesion detection sub-circuit according to an embodiment of this application;

[0068] Figure 4 This is a schematic diagram showing the connection relationship of the adhesion detection sub-circuit in the live wire detection circuit according to an embodiment of this application;

[0069] Figure 5 This is a schematic diagram showing the connection relationship of the adhesion detection sub-circuit in the neutral wire detection circuit according to an embodiment of this application;

[0070] Figure 6This is a schematic diagram showing the connection relationship of the adhesion detection sub-circuit in the live wire detection circuit when the switching transistor is a transistor according to an embodiment of this application.

[0071] Figure 7 This is a schematic diagram showing the connection relationship of the adhesion detection sub-circuit in the live wire detection circuit when the switching transistor is a MOSFET according to an embodiment of this application.

[0072] Figure 8 This is a schematic diagram showing the connection relationship of the adhesion detection sub-circuit in the neutral wire detection circuit when the switching transistor is a transistor according to an embodiment of this application.

[0073] Figure 9 This is a schematic diagram of an AC charging pile equipped with a relay adhesion detection circuit according to an embodiment of this application. Detailed Implementation

[0074] Some embodiments of this application are described below with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of this application and are not intended to limit the scope of protection of this application.

[0075] The relevant user personal information that may be involved in the various embodiments of this application is processed in strict accordance with the requirements of laws and regulations, following the principles of legality, legitimacy, and necessity, based on the reasonable purpose of the business scenario, and includes personal information that users actively provide or that is generated as a result of using the product / service, as well as personal information obtained with user authorization.

[0076] The personal information processed in this application will vary depending on the specific product / service scenario and will be based on the specific scenario in which the user uses the product / service. This may involve the user's account information, device information, driving information, vehicle information, or other related information. This application will treat the user's personal information and its processing with the utmost diligence.

[0077] This application attaches great importance to the security of users' personal information and has taken reasonable and feasible security protection measures that comply with industry standards to protect users' information and prevent unauthorized access, disclosure, use, modification, damage or loss of personal information.

[0078] The following describes an embodiment of the relay adhesion detection circuit provided in this application.

[0079] See appendix Figure 1 and attached Figure 2 , Figure 1 An example of the structure of a relay is shown. Figure 2 An exemplary structure of a relay adhesion detection circuit is shown. Figure 1As shown, the relays include a live wire relay and a neutral wire relay, which are respectively installed on the live wire and neutral wire in the AC circuit. Figure 2 As shown, the relay sticking detection circuit includes a live wire detection circuit and a neutral wire detection circuit, and both the live wire detection circuit and the neutral wire detection circuit include a sticking detection sub-circuit.

[0080] The following is in conjunction with the appendix Figure 3 To be continued Figure 4 The adhesion detection sub-circuit will be explained.

[0081] First, please refer to the appendix. Figure 3 , Figure 3 The main structure of the adhesion detection sub-circuit is illustrated exemplarily. For example... Figure 3 As shown, the adhesion detection sub-circuit includes an optocoupler, a switching transistor, a first detection terminal, a second detection terminal, a third detection terminal, and a signal output terminal.

[0082] The optocoupler includes a positive input terminal, a negative input terminal, and an output terminal. The positive input terminal of the optocoupler is connected to the first detection terminal, the negative input terminal is connected to the first main electrode of the switching transistor, and the output terminal is connected to the signal output terminal. The second main electrode of the switching transistor is connected to the second detection terminal, and the control electrode is connected to the third detection terminal.

[0083] The switching transistor includes a first main electrode, a second main electrode, and a control electrode. The first main electrode can be understood as the main electrode in the power input direction, and the second main electrode can be understood as the main electrode in the power output direction. The switching transistor can be a power electronic device such as a transistor or a MOSFET. Taking a transistor as an example, the first and second main electrodes are the collector and emitter of the transistor, respectively, and the control electrode is the base of the transistor. Taking a MOSFET as an example, the first and second main electrodes are the drain and source of the MOSFET, respectively, and the control electrode is the gate of the MOSFET. In some implementations, an NPN transistor or a MOSFET can be used.

[0084] When the first detection terminal is connected to the third detection terminal, the optocoupler is in a conducting state; therefore, the signal at the signal output terminal is the first signal. When the first detection terminal is not connected to the third detection terminal, the optocoupler is in a disconnected state; therefore, the signal at the signal output terminal is the second signal.

[0085] See appendix Figure 4 , Figure 4 The connection relationship of the adhesion detection sub-circuit in the live wire detection circuit is illustrated by way of example. Figure 4 In this diagram, K1 and K2 represent the live wire relay and the neutral wire relay, respectively; L_IN and L_OUT represent the input and output terminals of the live wire relay K1, respectively; and N_IN and N_OUT represent the input and output terminals of the neutral wire relay K2, respectively. Figure 4As shown, in the live wire detection circuit, the first detection terminal of the adhesion detection sub-circuit is connected to the input terminal L_IN of the live wire relay K1, the second detection terminal is connected to the input terminal N_IN of the neutral wire relay K2, and the third detection terminal is connected to the output terminal L_OUT of the live wire relay K1.

[0086] When the input terminal L_IN and output terminal L_OUT of the live wire relay K1 are stuck together, the first detection terminal and the third detection terminal will be connected, and the signal output terminal will be the first signal. When the input terminal L_IN and output terminal L_OUT of the live wire relay K1 are not stuck together, the first detection terminal and the third detection terminal will not be connected, and the signal output terminal will be the second signal. Therefore, by determining whether the signal output terminal is the first signal or the second signal, it is possible to determine whether the input terminal L_IN and output terminal L_OUT of the live wire relay K1 are stuck together.

[0087] See appendix Figure 5 , Figure 5 The connection relationship of the adhesion detection sub-circuit in the neutral wire detection circuit is illustrated exemplarily. Figure 5 As shown, in the neutral wire detection circuit, the first detection terminal of the adhesion detection sub-circuit is connected to the input terminal N_IN of the neutral wire relay K2, the second detection terminal is connected to the input terminal L_IN of the live wire relay K1, and the third detection terminal is connected to the output terminal N_OUT of the neutral wire relay K2.

[0088] When the input terminal N_IN and output terminal N_OUT of the neutral relay K2 are connected, the first detection terminal and the third detection terminal will be connected, and the signal output terminal will be the first signal. When the input terminal N_IN and output terminal N_OUT of the neutral relay K2 are not connected, the first detection terminal and the third detection terminal will not be connected, and the signal output terminal will be the second signal. Therefore, by determining whether the signal output terminal is the first signal or the second signal, it is possible to determine whether the input terminal N_IN and output terminal N_OUT of the neutral relay K2 are connected.

[0089] As can be seen, the relay sticking detection circuit based on the above circuit structure can accurately detect whether the live wire relay and the neutral wire relay are stuck together. Furthermore, compared to existing technologies, the above circuit structure does not require the use of relays with auxiliary contacts, isolated power supplies, miniature relays, or voltage transformers, resulting in smaller size and lower cost.

[0090] The adhesion detection sub-circuit will be further explained below.

[0091] In some implementations, the optocoupler's output includes a positive output and a negative output. The signal output of the adhesion detection sub-circuit is connected to the positive output of the optocoupler, and the negative output of the optocoupler is grounded. Furthermore, the adhesion detection sub-circuit also includes a first resistor, with its first end connected to a power supply and its second end connected in series between the signal output and the positive output of the optocoupler. The power supply is direct current (DC), not alternating current (AC) in an AC circuit.

[0092] See appendix Figure 6 , Figure 6 This example illustrates the connection relationship of the adhesion detection sub-circuit in the live wire detection circuit when the switching transistor is a bipolar transistor. Figure 6 In this diagram, DET represents the signal output terminal of the adhesion detection sub-circuit, GND represents analog ground, R6 represents the first resistor, VDD represents the power supply, E1 represents the optocoupler, and Q represents the transistor. For example... Figure 6 As shown, when the input terminal L_IN and output terminal L_OUT of the live wire relay are connected, the optocoupler E1 is turned on. The signal at the signal output terminal DET is periodically pulled high and low following the change in the AC power level, forming a square wave voltage signal. The frequency of this square wave voltage signal is the same as the frequency of the AC power in the AC line. When the input terminal L_IN and output terminal L_OUT of the live wire relay are not connected, the optocoupler E1 is turned off, and the signal at the signal output terminal DET is pulled up to a high-level voltage signal by the first resistor R6. The voltage of this high-level voltage signal is the same as the voltage of the power supply VDD.

[0093] See appendix Figure 7 , Figure 7 This example illustrates the connection relationship of the adhesion detection sub-circuit within the live wire detection circuit when the switching transistor is a MOSFET. Figure 6 Similarly, when the input terminal L_IN and output terminal L_OUT of the live wire relay are connected, the signal at the signal output terminal DET is a square wave voltage signal. When the input terminal L_IN and output terminal L_OUT of the live wire relay are not connected, the signal at the signal output terminal DET is a high-level voltage signal.

[0094] See appendix Figure 8 , Figure 8 This example illustrates the connection relationship of the adhesion detection sub-circuit within the neutral wire detection circuit when the switching transistor is a transistor. Figure 6 Similarly, when the input terminal N_IN and the output terminal N_OUT of the neutral relay are connected, the signal at the output terminal DET is a square wave voltage signal. When the input terminal N_IN and the output terminal N_OUT of the neutral relay are not connected, the signal at the output terminal DET is a high-level voltage signal.

[0095] In some implementations, the adhesion detection sub-circuit includes a second resistor. A first terminal of the second resistor is connected to the control electrode of the switching transistor, and a second terminal of the second resistor is connected to the second main electrode of the switching transistor. The following describes... Figure 6 The adhesion detection sub-circuit shown is used as an example for explanation. Figure 6 R3 in the diagram represents the second resistor. The first end of the second resistor R3 is connected to the control electrode (i.e., the base) of the switching transistor Q1, and the second end is connected to the second main electrode (i.e., the emitter) of the switching transistor Q1.

[0096] like Figure 6 As shown, when the input terminal L_IN and output terminal L_OUT of the live wire relay are not connected, the output terminal L_OUT is essentially floating, and the voltage can be considered as 0. At this time, there is no voltage difference across the second resistor R3, and the switching transistor Q1 cannot conduct. Therefore, the input terminal L_IN of the live wire relay and the input terminal N_IN of the neutral wire relay cannot form a circuit through the optocoupler E1, and the optocoupler E1 cannot conduct. The signal at the signal output terminal DET is pulled up to a high-level voltage signal by the first resistor R6.

[0097] When the input terminal L_IN and output terminal L_OUT of the live wire relay are stuck together, they are equivalent to the same point, and their voltages are the same. The output terminal L_OUT forms a circuit with the input terminal N_IN of the neutral wire relay through the second resistor R3. At this time, there is a voltage difference across the second resistor R3. By selecting an appropriate resistance value for the second resistor R3, the voltage difference across the second resistor R3 is made greater than the forward voltage drop between the control electrode and the second main electrode in the switching transistor Q1, thereby turning on the switching transistor Q1. After the switching transistor Q1 turns on, the input terminal L_IN of the live wire relay can form a circuit with the input terminal N_IN of the neutral wire relay through the optocoupler E1 and the switching transistor Q1. The optocoupler E1 then turns on, and the signal at the signal output terminal DET periodically rises and falls with the change in the AC voltage level, forming a square wave voltage signal.

[0098] In some implementations, the adhesion detection sub-circuit includes a diode. The anode of the diode is connected to the second main electrode of the switching transistor, and the cathode of the diode is connected to the third detection terminal. The following describes... Figure 6 The adhesion detection sub-circuit shown is used as an example for explanation. Figure 6 D1 in the diagram represents a diode.

[0099] like Figure 6As shown, the anode of diode D1 is connected to the second main electrode (i.e., emitter) of switching transistor Q1, and the cathode of diode D1 is connected to the third detection terminal, which is connected to the input terminal N_IN of the neutral relay. Therefore, the cathode of diode D1 can be connected to the input terminal N_IN of the neutral relay. Diode D1 is used to cut off reverse AC signals, keeping the voltage drop across the second resistor R3 positive. In some embodiments, diode D1 should be selected with a reverse withstand voltage greater than or equal to 1kV to prevent surge damage and other interference from damaging subsequent circuits.

[0100] In some embodiments, the adhesion detection sub-circuit includes a first Zener diode. The anode of the first Zener diode is connected to the third detection terminal, and the cathode of the first Zener diode is connected to the control electrode of the switching transistor. If the adhesion detection sub-circuit includes the diode in the above embodiments, the cathode of the first Zener diode can be connected to the anode of the aforementioned diode. The following describes... Figure 6 The adhesion detection sub-circuit shown is used as an example for explanation. Figure 6 Z1 in the diagram represents the first Zener diode.

[0101] like Figure 6 As shown, the anode of the first Zener diode Z1 is connected to the anode of diode D1, and the cathode of the first Zener diode Z1 is connected to the control electrode (i.e., base) of the switching transistor Q1. The first Zener diode Z1 is used to clamp the voltage across the second resistor R3. When the voltage across the second resistor R3 exceeds the Zener voltage of the first Zener diode Z1, the voltage between the control electrode (i.e., base) and the second main electrode (i.e., emitter) of the switching transistor Q1 is clamped to the Zener voltage of the first Zener diode Z1, thereby protecting the switching transistor from damage.

[0102] In some embodiments, the adhesion detection sub-circuit includes a second Zener diode. The anode of the second Zener diode is connected to the first main electrode of the switching transistor, and the cathode of the second Zener diode is connected to the negative input terminal of the optocoupler. (The following is an example...) Figure 6 The adhesion detection sub-circuit shown is used as an example for explanation. Figure 6 Z2 in the diagram represents the second Zener diode.

[0103] like Figure 6 As shown, the anode of the second Zener diode Z2 is connected to the first main electrode (i.e., collector) of the switching transistor Q1, and the cathode is connected to the negative input terminal of the optocoupler E1. When the switching transistor Q1 is on, the second Zener diode Z2 is in a reverse breakdown state, used for circuit voltage reduction; when the switching transistor Q1 is off, the second Zener diode Z2 is in a reverse cutoff state, used to cut off the L_IN voltage, preventing the L_IN voltage from being directly applied to the two ends of the switching transistor Q1, thus protecting the switching transistor Q1.

[0104] In some embodiments, the adhesion detection subcircuit includes a first current-limiting resistor unit and a second current-limiting resistor unit. The first current-limiting resistor unit is connected in series between the first detection terminal and the positive input terminal of the optocoupler, and includes one or more current-limiting resistors connected in series. The second current-limiting resistor unit is connected in series between the third detection terminal and the control electrode of the switching transistor, and includes one or more current-limiting resistors connected in series. The following describes... Figure 6 The adhesion detection sub-circuit shown is used as an example for explanation. Figure 6 Resistors R4 and R5 are connected in series to form the first current-limiting resistor unit, and resistors R1 and R2 are connected in series to form the second current-limiting resistor. Multiple resistors are used in series to distribute the power across the resistors, preventing any single resistor from exceeding its power limit.

[0105] Another aspect of this application provides an AC charging station.

[0106] In the embodiments of the AC charging pile provided in this application, the AC charging pile includes a live wire relay and a neutral wire relay disposed on the live wire and neutral wire of the AC line, and also includes the relay adhesion detection circuit described in the aforementioned circuit embodiments. The connection structure of the live wire relay and the neutral wire relay is as follows: Figure 1 As shown, the connection relationship between the relay adhesion detection circuit and the live wire relay and the neutral wire relay is the same as the connection relationship in the aforementioned circuit embodiment.

[0107] In some implementations, the AC charging pile includes a main control circuit configured to: detect the signal output of the adhesion detection sub-circuit in the live wire detection circuit; if the signal is a first signal, it is determined that the live wire relay is stuck; if the signal is a first signal, it is determined that the live wire relay is not stuck. Also, it detects the signal output of the adhesion detection sub-circuit in the neutral wire detection circuit; if the signal is a first signal, it is determined that the neutral wire relay is stuck; if the signal is a first signal, it is determined that the neutral wire relay is not stuck. Through the above main control circuit, it is possible to conveniently and accurately detect whether the live wire relay and the neutral wire relay are stuck. Furthermore, since an optocoupler is provided in the adhesion detection sub-circuit, this optocoupler can isolate the adhesion detection sub-circuit from the main control circuit, thereby avoiding interference from the relay's environment and improving the reliability of the main control circuit. The first signal and the second signal have the same meaning as the first signal and the second signal in the aforementioned circuit embodiments, and will not be repeated here.

[0108] The following is in conjunction with the appendix Figure 9 The above main control circuit will be explained using a live wire detection circuit as an example. Figure 9 As shown, the AC charging station includes a live wire relay K1 and a neutral wire relay K2. Figure 9The adhesion detection sub-circuit in the circuit is the adhesion detection sub-circuit in the live wire detection circuit, and DET is the signal output terminal of the adhesion detection sub-circuit. The main control circuit can detect the signal at this signal output terminal and determine whether the live wire relay has stuck based on the signal type.

[0109] The working process of an AC charging station is as follows:

[0110] Before charging the electric vehicle, the AC charging station is plugged into the charging port of the electric vehicle. The main control circuit checks whether the live wire relay and the neutral wire relay are stuck. If either relay is stuck, charging will not start. If neither relay is stuck, charging will start and begin charging the electric vehicle.

[0111] The background section introduces five conventional methods for detecting relay sticking. The third method detects neutral contact faults by adding an isolated power supply and a small relay. Before charging begins, the small relay is closed, creating a circuit on the output side of the neutral relay's contact through a resistor, neutral contact, diode, optocoupler, and other components, thus detecting neutral relay contact sticking faults. This method is not only costly, bulky, and carries safety risks, but if implemented in an AC charging station, it can also reduce the insulation resistance and dielectric strength between the input side and ground, potentially preventing the AC charging station from meeting insulation resistance and dielectric strength requirements. The relay sticking detection circuit provided in this application effectively avoids the problems of low insulation resistance and dielectric strength, ensuring that the AC charging station meets the requirements.

[0112] The following is based on Figure 6 Taking the adhesion detection sub-circuit shown as an example, the tests for insulation resistance and dielectric strength are explained respectively.

[0113] 1. The test for insulation resistance is explained.

[0114] The insulation resistance test of AC charging piles is conducted under a preset DC voltage, which can be 500V DC voltage.

[0115] Short-circuit the input live wire and neutral wire to form the first short-circuit circuit, and test the insulation resistance 1 between this first short-circuit circuit and the ground.

[0116] Short-circuit the output live wire and neutral wire to form a second short-circuit circuit, and test the insulation resistance 2 between this second short-circuit circuit and the ground.

[0117] Test the insulation resistance 3 between the first short-circuit circuit and the second short-circuit circuit.

[0118] Since the relay sticking detection circuit cannot directly form a circuit with the ground, the relay sticking detection circuit will not affect the above-mentioned insulation resistance 1 and insulation resistance 2.

[0119] See appendix Figure 6 When testing insulation resistance 3, since the input live wire is short-circuited to the neutral wire and the output live wire is short-circuited to the neutral wire, only the output terminal L_OUT of the live wire relay, resistors R1, R2, and R3, diode D1, and the input terminal N_OUT of the neutral wire relay form a circuit. In this case, insulation resistance 3 depends on the circuit resistance of this circuit. Therefore, by adjusting this circuit resistance, the insulation resistance 3 can be changed to ensure that the AC charging pile meets the insulation resistance requirements.

[0120] 2. Explanation of the dielectric strength test.

[0121] The dielectric strength test of AC charging piles is conducted under a preset DC voltage or a preset AC voltage to test the following dielectric strengths. The preset DC voltage can be 2120V DC voltage, and the preset AC voltage can be 1500V DC voltage.

[0122] Short-circuit the input live wire and neutral wire to form the first short-circuit circuit, and test the dielectric strength 1 between this first short-circuit circuit and the ground.

[0123] Short-circuit the output live wire and neutral wire to form a second short-circuit circuit, and test the dielectric strength 2 between this second short-circuit circuit and the ground.

[0124] Test the dielectric strength 3 between the first short-circuit circuit and the second short-circuit circuit.

[0125] Since the relay adhesion detection circuit cannot directly form a circuit with the ground, the relay adhesion detection circuit will not affect the dielectric strength 1 and dielectric strength 2 mentioned above.

[0126] See appendix Figure 6 When testing dielectric strength 3, since the input live wire and neutral wire are short-circuited, and the output live wire and neutral wire are also short-circuited, only the output terminal L_OUT of the live wire relay, resistors R1, R2, and R3, diode D1, and the input terminal N_OUT of the neutral wire relay form a circuit. In this case, dielectric strength 3 depends on this circuit. Therefore, high-voltage resistors with appropriate resistance values ​​can be selected for resistors R1, R2, and R3 to ensure that the AC charging pile meets the dielectric strength requirements.

[0127] The technical solution of this application has been described above with reference to one embodiment shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of this application is obviously not limited to these specific embodiments. Without departing from the principles of this application, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the scope of protection of this application.

Claims

1. A relay adhesion detection circuit, wherein the relay comprises a live wire relay and a neutral wire relay respectively disposed on the live wire and neutral wire in an AC line, characterized in that, The circuit includes a live wire detection circuit and a neutral wire detection circuit, and both the live wire detection circuit and the neutral wire detection circuit include an adhesion detection sub-circuit. The adhesion detection sub-circuit includes a second resistor, an optocoupler, a switching transistor, a first detection terminal, a second detection terminal, a third detection terminal, and a signal output terminal. The first detection terminal and the first main electrode of the switching transistor are respectively connected to the positive and negative input terminals of the optocoupler. The second detection terminal and the third detection terminal are respectively connected to the second main electrode and the control electrode of the switching transistor. The first terminal of the second resistor is connected to the control electrode of the switching transistor, and the second terminal of the second resistor is connected to the second main electrode of the switching transistor. The signal output terminal is connected to the output terminal of the optocoupler. When the first detection terminal and the third detection terminal are connected and disconnected, the signals at the signal output terminal are a first signal and a second signal, respectively. In the live wire detection circuit, the first detection terminal of the adhesion detection sub-circuit is connected to the input terminal of the live wire relay, the second detection terminal is connected to the input terminal of the neutral wire relay, and the third detection terminal is connected to the output terminal of the live wire relay. In the neutral wire detection circuit, the first detection terminal of the adhesion detection sub-circuit is connected to the input terminal of the neutral wire relay, the second detection terminal is connected to the input terminal of the live wire relay, and the third detection terminal is connected to the output terminal of the neutral wire relay.

2. The relay adhesion detection circuit according to claim 1, characterized in that, The adhesion detection sub-circuit includes a first resistor; The signal output terminal is connected to the positive output terminal of the optocoupler, the first end of the first resistor is connected to the power supply, the second end of the first resistor is connected in series between the signal output terminal and the positive output terminal of the optocoupler, and the negative output terminal of the optocoupler is grounded.

3. The relay adhesion detection circuit according to claim 2, characterized in that, The first signal is a square wave voltage signal, and the second signal is a high-level voltage signal; The frequency of the square wave voltage signal is the same as the frequency of the alternating current in the alternating current line.

4. The relay adhesion detection circuit according to claim 1, characterized in that, The adhesion detection sub-circuit includes a diode; The anode of the diode is connected to the second main electrode of the switching transistor, and the cathode of the diode is connected to the third detection terminal.

5. The relay adhesion detection circuit according to claim 1, characterized in that, The adhesion detection sub-circuit includes a first Zener diode; The anode of the first Zener diode is connected to the third detection terminal, and the cathode of the first Zener diode is connected to the control electrode of the switching transistor.

6. The relay adhesion detection circuit according to claim 1, characterized in that, The adhesion detection sub-circuit includes a second Zener diode; The anode of the second Zener diode is connected to the first main electrode of the switching transistor, and the cathode of the second Zener diode is connected to the negative input terminal of the optocoupler.

7. The relay adhesion detection circuit according to claim 1, characterized in that, The adhesion detection sub-circuit includes a first current-limiting resistor unit and a second current-limiting resistor unit. The first current-limiting resistor unit is connected in series between the first detection terminal and the positive input terminal of the optocoupler, and the first current-limiting resistor unit includes one or more current-limiting resistors connected in series. The second current-limiting resistor unit is connected in series between the third detection terminal and the control electrode of the switching transistor, and the second current-limiting resistor unit includes one or more current-limiting resistors connected in series.

8. The relay adhesion detection circuit according to claim 1, characterized in that, The switching transistor is a bipolar transistor or a MOSFET.

9. An AC charging pile, the AC charging pile comprising a live wire relay and a neutral wire relay disposed on the live wire and neutral wire of an AC line, characterized in that, The AC charging pile includes the relay adhesion detection circuit according to any one of claims 1 to 8.

10. The AC charging pile according to claim 9, characterized in that, The AC charging pile includes a main control circuit, which is configured to: The signal output of the adhesion detection sub-circuit in the live wire detection circuit is detected; if the signal is the first signal, it is determined that the live wire relay is stuck; if the signal is the second signal, it is determined that the live wire relay is not stuck. The signal output of the adhesion detection sub-circuit in the neutral wire detection circuit is detected; if the signal is the first signal, it is determined that the neutral wire relay is stuck; if the signal is the second signal, it is determined that the neutral wire relay is not stuck.

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