阅读说明：本技术 一种电动汽车交流桩主继电器粘连检测系统及方法 (Electric automobile alternating current pile main relay adhesion detection system and method ) 是由 邓思维 王鹏超 闫寒明 刘小龙 张东江 翟刚锋 徐武峰 唐智翀 凌凯 岑广钊 周 于 2020-12-22 设计创作，主要内容包括：本发明提供一种电动汽车交流桩主继电器粘连检测系统及方法,包括：模拟检测模块,接收控制信号,与N主继电器的功率输出端连接,输出侧输出模拟信号到控制器；数字检测模块,输入侧连接交流桩L主继电器和N主继电器的功率输出端,输出侧输出数字电平信号至控制器；控制器,与模拟检测模块、数字检测模块连接,通过检测模拟检测模块输出的模拟信号的值,判断N主继电器的通断状态；通过检测数字检测模块输出的数字电平信号,判断数字检测模块是否导通,进而判断L、N主继电器的开通情况,继而判断主继电器粘连检测。本发明不需要动作主继电器,完整的检测到继电器的所有状态。(The invention provides an electric automobile alternating current pile main relay adhesion detection system and method, which comprises the following steps: the analog detection module receives the control signal, is connected with the power output end of the N main relays, and outputs an analog signal to the controller at the output side; the input side of the digital detection module is connected with the power output ends of the L main relay and the N main relay of the alternating-current pile, and the output side of the digital detection module outputs a digital level signal to the controller; the controller is connected with the analog detection module and the digital detection module and judges the on-off state of the N main relays by detecting the value of an analog signal output by the analog detection module; through the digital level signal that detects digital detection module output, judge whether digital detection module switches on, and then judge L, N main relay's the condition of opening, then judge main relay adhesion and detect. The invention does not need to operate the main relay and completely detects all the states of the relay.)

1. The utility model provides an electric automobile exchanges stake main relay adhesion detecting system which characterized in that includes:

the analog detection module receives the control signal, is connected with the power output end of the N main relays, and outputs an analog signal to the controller at the output side;

the input side of the digital detection module is connected with the power output ends of the L main relay and the N main relay of the alternating-current pile, and the output side of the digital detection module outputs a digital level signal to the controller;

the controller is connected with the analog detection module and the digital detection module, and the analog detection module is connected with the digital detection module by taking the power output end of the N main relays as a node;

the controller judges the on-off state of the N main relays by detecting the value of the analog signal output by the analog detection module; and judging whether the digital detection module is conducted or not by detecting the digital level signal output by the digital detection module, and further judging L, N the opening condition of the main relay, wherein,

when the analog detection module is turned off:

l, N the main relays are all in a closed state if the digital control module is on;

if the digital control module is not switched on, three states are possible: only L main relay is closed, only N main relay is closed, or L, N main relay is the open mode, at this moment, opens simulation detection module, then:

a. if the state of the digital control module is changed, the L main relay is in a closed state, and the N main relay is in an open state, namely, only the L main relay is closed;

b. and if the state of the digital control module is not changed, the L main relay is in a closed state, and the controller judges the state of the N main relay according to the output of the analog detection module.

2. The system of claim 1, wherein the simulation detection module comprises:

the control part selects a relay as a control device, and when the controller outputs a high level, the relay is closed, so that the power output end of the N main relays is connected with the detection part;

the detection part detects by using a resistance voltage division principle, is connected with the ground of the single-phase alternating current with reference to the ground, provides a path for the input end current of the digital detection module, and ensures the difference of sampling values in different states.

3. The system of claim 2, wherein the simulation detection module further comprises:

and the protection part is used for preventing the influence of overvoltage on the controller and stabilizing the output analog signal.

4. The system for detecting adhesion of the main relay of the alternating current pile of the electric vehicle as claimed in claim 1, wherein the digital detection module comprises an optical coupler, an input side of the digital detection module is connected with a current limiting resistor, an output side of the digital detection module outputs a digital signal, when the optical coupler is not conducted, the digital signal outputs a high level or a low level, and when the optical coupler is conducted, the digital detection module outputs a periodic square wave signal.

5. The system for detecting adhesion of the main relay of the alternating current pile of the electric automobile according to claim 4, wherein the current limiting resistor is selected according to the following conditions:

when the L main relay is in the closed state, the current limiting resistor enables the optocoupler to be directly switched on if the N main relay is also in the closed state;

if the N main relays are in an off state, the current-limiting resistor enables the input end of the optocoupler to be switched on after the analog detection module is switched on.

6. The system of claim 1, wherein the controller turns off L, N the main relay after completely determining the status of the main relay, and compares the result with the required status to draw a conclusion about whether the relay is stuck.

7. A method for detecting adhesion of a main relay of an alternating current pile of an electric vehicle is characterized in that the detection system of any one of claims 1 to 6 is adopted, and the method comprises the following steps:

s1, when the detection is started, the analog detection module is in the off state, and the controller first reads the output of the digital detection module:

if a periodic square wave signal is detected, the digital detection module is turned on, and it can be determined L, N that the main relay is in a closed state;

if the detected digital signal is at a fixed level, it indicates that the digital detection module is not conducting, and the relay may have three states: only the L main relay is closed, only the N main relay is closed, or the L, N main relay is in an open state;

s2, the controller sends a control signal to turn on the analog detection module, and the analog detection module provides another path for the input end of the digital detection module after the access, so that the state of the digital detection module may change, and the controller reads the output of the digital detection module:

if the state of the digital detection module changes from non-conducting to conducting, it can be determined that the L main relay is in the closed state and the N main relay is in the open state, i.e. only the L main relay is closed;

if the state of the digital detection module is not changed and still not conductive, it is possible to determine that the L main relay is in the off state; at the moment, the controller detects the analog signal voltage output by the analog detection module, and judges the opening condition of the N main relays according to the detected analog voltage: if the N main relays are in a closed state, only the N main relays are closed; if the N main relays are in an off state, namely L, N the main relays are in an off state;

and S3, after completely judging the state of the L, N main relay, the controller closes the simulation detection module and compares the result with the required state to draw a conclusion whether the relay is adhered or not.

8. The method for detecting adhesion of the main relay of the alternating current pile of the electric vehicle as claimed in claim 7, wherein the digital detection module adopts an optocoupler as a control component, and the analog detection module selects a relay as a control component.

9. A terminal comprising a memory, a processor and a computer program stored in the memory and executable on the processor, wherein the processor is configured to execute the method for detecting adhesion of an ac pole main relay of an electric vehicle according to claim 7 or 8 when executing the program.

10. A computer-readable storage medium having a computer program stored thereon, wherein the program, when executed by a processor, is configured to perform the method for detecting adhesion of an ac post main relay of an electric vehicle according to claim 7 or 8.

Technical Field

The invention relates to the field of electric automobile charging and battery replacement, in particular to a system and a method for detecting adhesion of a main relay of an electric automobile alternating current pile.

Background

Modern mainstream alternating current charging piles for electric automobiles use relays to control single-phase alternating current L and N lines; however, many current methods for detecting the adhesion of the relay are not suitable for the situation or have disadvantages, such as incomplete state detection; the service life of the main relay is shortened; the software needs complex control logic and the like.

Through retrieval, chinese patent application No. CN201611179362 discloses a charging device, a relay adhesion detection method, and a charging method of an electric vehicle, wherein in the charging device, a detection circuit includes a rectification module, an optocoupler, a first diode, a pull-up resistor, and a control module, wherein an input end of the rectification module is connected to a first end of a charging gun, an output end of the rectification module is connected to an anode of a light emitting diode in the optocoupler, a cathode of the light emitting diode in the optocoupler is connected to a second end of the charging gun, an anode of the first diode is connected to a second end of the charging gun, a cathode of the first diode is connected to an anode of the light emitting diode in the optocoupler, a collector of a triode in the optocoupler is connected to a high level through the pull-up resistor, and an emitter of the triode; and after the control module controls the current relay to be detected to be switched off, the control module controls the other relay to be switched on, and whether the current relay is adhered or not is judged according to a voltage signal of a collector of a triode in the optocoupler. However, the patent cannot completely detect the adhesion condition of the relay; the relay sticking condition includes two conditions: can not be normally closed or opened; when one main relay cannot be normally closed and the other main relay cannot be normally opened, the method cannot detect the failure; meanwhile, the main relay needs to be turned on and off when adhesion is detected, and the normal service time of the main relay is shortened due to the limited service life of the relay.

Chinese patent application No. 201910046694.5 discloses a relay contact adhesion detection circuit and detection device thereof, including: the high-voltage division module is connected with the two contacts of the relay and is used for carrying out voltage division sampling on the high-voltage voltages of the two contacts of the relay; the absolute value operation module is used for receiving the divided voltage sampling voltage and calculating the absolute value of the difference value of the two divided voltage sampling voltages; the threshold comparison module is used for receiving the absolute value and comparing the absolute value with a preset threshold value; the processor module is used for receiving the comparison result, judging whether the contacts of the relay are adhered according to the comparison result and outputting a judgment result; the method is not suitable for detecting the adhesion of the AC N-line relay.

Disclosure of Invention

Aiming at the defects in the prior art, the invention aims to provide a system and a method for detecting the adhesion of a main relay of an alternating current pile of an electric vehicle.

According to one aspect of the invention, an adhesion detection system for a main relay of an electric automobile alternating current pile is provided, which comprises:

the analog detection module receives the control signal, is connected with the power output end of the N main relays, and outputs an analog signal to the controller at the output side;

the input side of the digital detection module is connected with the power output ends of the L main relay and the N main relay of the alternating-current pile, and the output side of the digital detection module outputs a digital level signal to the controller;

the controller is connected with the analog detection module and the digital detection module, and the analog detection module is connected with the digital detection module by taking the power output end of the N main relays as a node;

the controller judges the on-off state of the N main relays by detecting the value of the analog signal output by the analog detection module; and judging whether the digital detection module is conducted or not by detecting the digital level signal output by the digital detection module, and further judging L, N the opening condition of the main relay, wherein,

when the analog detection module is turned off:

l, N the main relays are all in a closed state if the digital control module is on;

if the digital control module is not switched on, three states are possible: only L main relay is closed, only N main relay is closed, or L, N main relay is the open mode, at this moment, opens simulation detection module, then:

a. if the state of the digital control module is changed, the L main relay is in a closed state, and the N main relay is in an open state, namely, only the L main relay is closed;

b. and if the state of the digital control module is not changed, the L main relay is in a closed state, and the controller judges the state of the N main relay according to the output of the analog detection module.

Optionally, the analog detection module includes:

the control part selects a relay as a control device, and when the controller outputs a high level, the relay is closed, so that the power output end of the N main relays is connected with the detection part;

the detection part detects by using a resistance voltage division principle, is connected with the ground of the single-phase alternating current with reference to the ground, provides a path for the input end current of the digital detection module, and ensures the difference of sampling values in different states.

Optionally, the analog detection module further includes:

and the protection part is used for preventing the influence of overvoltage on the controller and stabilizing the output analog signal.

Optionally, the digital detection module includes an optical coupler, an input side of the digital detection module is connected to the current-limiting resistor, an output side of the digital detection module outputs a digital signal, when the optical coupler is not turned on, the digital detection module outputs a high level or a low level, and when the optical coupler is turned on, the digital detection module outputs a periodic square wave signal.

The current limiting resistor can be roughly Andy, and the selection conditions are as follows:

when the L main relay is in the closed state, the current limiting resistor enables the optocoupler to be directly switched on if the N main relay is also in the closed state;

if the N main relays are in an off state, the current-limiting resistor enables the input end of the optocoupler to be switched on after the analog detection module is switched on.

Optionally, after completely determining L, N the state of the main relay, the controller turns off the simulation detection module and compares the result with the required state to draw a conclusion as to whether the relay is stuck.

According to a second aspect of the invention, a method for detecting adhesion of a main relay of an electric vehicle alternating current pile is provided, and the method adopts the detection system, and comprises the following steps:

s1, when the detection is started, the analog detection module is in the off state, and the controller first reads the output of the digital detection module:

if a periodic square wave signal is detected, the digital detection module is turned on, and it can be determined L, N that the main relay is in a closed state;

if the detected digital signal is at a fixed level, it indicates that the digital detection module is not conducting, and the relay may have three states: only the L main relay is closed, only the N main relay is closed, or the L, N main relay is in an open state;

s2, the controller sends a control signal to turn on the analog detection module, and the analog detection module provides another path for the input end of the digital detection module after the access, so that the state of the digital detection module may change, and the controller reads the output of the digital detection module:

if the state of the digital detection module changes from non-conducting to conducting, it can be determined that the L main relay is in the closed state and the N main relay is in the open state, i.e. only the L main relay is closed;

if the state of the digital detection module is not changed and still not conductive, it is possible to determine that the L main relay is in the off state; at the moment, the controller detects the analog signal voltage output by the analog detection module, and judges the opening condition of the N main relays according to the detected analog voltage: if the N main relays are in a closed state, only the N main relays are closed; if the N main relays are in an off state, namely L, N the main relays are in an off state;

and S3, after completely judging the state of the L, N main relay, the controller closes the simulation detection module and compares the result with the required state to draw a conclusion whether the relay is adhered or not.

Optionally, the digital detection module uses an optocoupler as a control component, and the analog detection module selects a relay as a control device.

According to a third aspect of the present invention, there is provided a terminal, including a memory, a processor, and a computer program stored in the memory and executable on the processor, where the processor is configured to execute the method for detecting adhesion of a main relay of an ac pole of an electric vehicle.

According to a fourth aspect of the present invention, there is provided a computer-readable storage medium, having a computer program stored thereon, where the computer program is used to execute the method for detecting the sticking of the main relay of the ac pole of the electric vehicle when the computer program is executed by a processor.

Compared with the prior art, the embodiment of the invention has at least one of the following beneficial effects:

according to the system and the method for detecting the adhesion of the main relay of the alternating current pile of the electric vehicle, the on-off states of the single-phase alternating current L and N relays can be completely judged, and the state detection is complete.

According to the system and the method for detecting the adhesion of the main relay of the alternating current pile of the electric vehicle, the main relay does not need to be operated, a hardware circuit occupies a small space and is low in cost, and the service life of the main relay is prolonged.

According to the system and the method for detecting the adhesion of the main relay of the alternating current pile of the electric vehicle, software control logic is simple.

Drawings

Other features, objects and advantages of the invention will become more apparent upon reading of the detailed description of non-limiting embodiments with reference to the following drawings:

fig. 1 is a schematic structural diagram of an adhesion detection system for a main relay of an electric vehicle ac pile according to an embodiment of the present invention.

Fig. 2 is a flowchart of a method for detecting adhesion of a main relay of an ac pile of an electric vehicle according to an embodiment of the present invention.

Fig. 3 is a circuit diagram of an ac post and a relay of an electric vehicle according to an embodiment of the invention.

Fig. 4 is a circuit diagram of a controller according to an embodiment of the invention.

FIG. 5 is a circuit diagram of an analog detection module according to an embodiment of the invention.

Fig. 6 is a circuit diagram of a digital detection module according to an embodiment of the invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

Fig. 1 is a schematic structural diagram of an adhesion detection system for a main relay of an electric vehicle ac pile according to an embodiment of the present invention. Referring to fig. 1, in this embodiment, an electric automobile exchanges stake main relay adhesion detecting system includes: analog detection module, digital detection module and controller, wherein: the analog detection module receives the control signal, is connected with the power output end of the N main relays, and outputs an analog signal to the controller at the output side; the input side of the digital detection module is connected with the power output ends of the L main relay and the N main relay of the alternating-current pile, and the output side outputs a digital level signal to the controller; the controller is connected with the analog detection module and the digital detection module, and the analog detection module is connected with the digital detection module by taking the power output end of the N main relays as a node; the controller judges the on-off state of the N main relays by detecting the value of the analog signal output by the analog detection module; and judging whether the digital detection module is conducted or not by detecting the digital level signal output by the digital detection module, and further judging L, N the opening condition of the main relay.

When the analog detection module is turned off: if the digital control module is conducted, L, N the main relays are all in a closed state; if the digital control module is not turned on, three states are possible: only L main relay is closed, only N main relay is closed, or L, N main relay is the off-state, at this moment, opens simulation detection module, then:

a. if the state of the digital control module is changed, the L main relay is in a closed state, and the N main relay is in an open state, namely, only the L main relay is closed;

b. if the state of the digital control module is not changed, the L main relay is in a closed state, and the controller judges the state of the N main relays according to the output of the analog detection module.

In another embodiment, the analog detection module includes: the control part selects the relay as a control device, and when the controller outputs a high level, the relay is closed, so that the power output end of the N main relays is connected with the detection part; the detection part utilizes a resistance voltage division principle to detect, and the reference ground of the detection part is connected with the ground of the single-phase alternating current, so that a path is provided for the input end current of the digital detection module, and the difference of sampling values in different states is ensured.

In another preferred embodiment, the analog detection module may further include a protection circuit, where the protection circuit includes an RC filter, a clamping diode and a voltage stabilizing transistor, and stabilizes the output analog signal while preventing the controller from being affected by an overvoltage.

In another preferred embodiment, the digital detection module comprises an optical coupler, the input side of the optical coupler is connected with the current limiting resistor, the output side of the optical coupler outputs a digital signal, when the optical coupler is not switched on, the digital signal outputs a high level or a low level, and when the optical coupler is switched on, the digital detection module outputs a periodic square wave signal. Specifically, the current limiting resistor is selected according to the following conditions: when the L main relay is in a closed state, if the N main relay is also in a closed state, the current-limiting resistor can enable the optocoupler to be directly conducted; if the N main relays are in an off state, the current-limiting resistor enables the input end of the optocoupler to be switched on after the analog detection module is switched on.

The embodiment of the invention can completely judge the switching states of the single-phase alternating current L and N relays, has complete state detection, does not need to actuate the main relay, has small occupied space of a hardware circuit and low cost, and prolongs the service life of the main relay.

Fig. 2 is a flowchart of a method for detecting adhesion of a main relay of an ac pile of an electric vehicle according to an embodiment of the present invention. Referring to fig. 2, the method for detecting adhesion of the main relay of the alternating current pile of the electric vehicle in the embodiment is performed by using the detection system shown in fig. 1, where the method includes:

s1, when the detection is started, the analog detection module is in the off state, and the controller first reads the output of the digital detection module:

if a periodic square wave signal is detected, the digital detection module is turned on, and it can be determined L, N that the main relay is in a closed state;

if the detected digital signal is at a fixed level, it indicates that the digital detection module is not conducting, and the relay may have three states: only the L main relay is closed, only the N main relay is closed, or the L, N main relay is in an open state;

s2, the controller sends a control signal to turn on the analog detection module, and the analog detection module provides another path for the input end of the digital detection module after the access, so that the state of the digital detection module may change, and the controller reads the output of the digital detection module:

if the state of the digital detection module changes from non-conducting to conducting, it can be determined that the L main relay is in the closed state and the N main relay is in the open state, i.e. only the L main relay is closed;

if the state of the digital detection module is not changed and still not conductive, it is possible to determine that the L main relay is in the off state; at the moment, the controller detects the analog signal voltage output by the analog detection module, and judges the opening condition of the N main relays according to the detected analog voltage: if the N main relays are in a closed state, only the N main relays are closed; if the N main relays are in an off state, namely L, N the main relays are in an off state;

and S3, after completely judging the state of the L, N main relay, the controller closes the simulation detection module and compares the result with the required state to draw a conclusion whether the relay is adhered or not.

Based on the foregoing embodiment, in another embodiment of the present invention, a terminal is further provided, which includes a memory, a processor, and a computer program stored in the memory and executable on the processor, and when the processor executes the program, the processor may be configured to execute the foregoing method for detecting adhesion of an ac pole main relay of an electric vehicle.

Based on the foregoing embodiments, in another embodiment of the present invention, a computer-readable storage medium is further provided, where a computer program is stored, and the computer program is executed by a processor to execute the foregoing adhesion detection method for an ac pole main relay of an electric vehicle.

In order to better illustrate the above technical solutions, specific application examples are provided below, but it should be understood that the following specific examples are not intended to limit the present invention.

Referring to fig. 1 and 3-6, in an embodiment of the present invention, a system for detecting adhesion of a main relay of an ac pile of an electric vehicle includes an analog detection module, a digital detection module, a controller, a peripheral ac pile and relay circuit, and 5V and 3.3V power supplies.

Fig. 3 is a circuit diagram of an ac post and a relay of an electric vehicle according to an embodiment of the invention. As shown in fig. 3, the ac stub and relay circuit includes a relay RL1 and a relay RL2, L and N are single-phase ac inputs of a relay RL1 and a relay RL2, respectively, L _ C and N _ C are outputs of a relay RL1 and a relay RL2, respectively, a relay RL1 and a relay RL2 are connected to a control output terminal of the controller, and when the control output terminal of the controller is at a high level, the two relays are turned on to output ac power.

Fig. 4 is a circuit diagram of a controller according to an embodiment of the invention. As shown in fig. 4, the controller U3 is a chip. A control output end and a DO output end of the controller U3 are respectively connected with the alternating current pile, the relay circuit and the analog detection module to respectively control the on-off of the main relay and the analog detection module, and a DI input end and an AI input end of the controller U3 are respectively connected with the digital detection module and the analog detection module and are used for detecting output signals of the digital detection module and the analog detection module.

FIG. 5 is a circuit diagram of an analog detection module according to an embodiment of the invention. As shown in fig. 5, the analog detection module includes a controller and a detection circuit, in order to ensure the difference of different detection values, the controller selects the relay RL3 as a control device to be connected to the DO output terminal of the controller U3, and when the DO output terminal of the controller U3 is at a high level, the relay RL3 is closed, so that the power output terminal N _ C of the relay RL2 is connected to the detection circuit; the detection circuit is provided with a resistor R9, a resistor R6 and a resistor R3, the detection circuit utilizes a resistor voltage division principle, the resistance value of a voltage division resistor is large, the protection controller U3 cannot inject large current, when the relay RL2 is in a closed state, the voltage value of the output AI is divided by R3 and R9, when the relay RL2 is in an open state, the voltage value of the output AI is divided by R3, R9 and R6, the on-off condition of the relay RL2 can be judged according to different AI values, in addition, the reference ground of the detection circuit is connected with the ground of single-phase alternating current, a path can be provided for the input end current of the digital detection module, and the difference of sampling values under different states is ensured.

Fig. 6 is a circuit diagram of a digital detection module according to an embodiment of the invention. As shown in fig. 6, the digital detection module selects the optocoupler U1 with a wide conduction current range as a control device, and if TL121 is greater than 0.1mA, the optocoupler U1 can be turned on, and when the relay RL1 and the relay RL2 are both in a closed state, the maximum value of the primary side current of the optocoupler U1 is about 3.1mA, and at this time, the optocoupler U1 is turned on, and because the optocoupler is an alternating current signal source, a square wave signal is output from the DI output end of; when the relay RL1 is in a closed state and the relay RL2 is in an open state, the analog detection module is connected, current on the input side of the optocoupler U1 flows into the ground through the resistor R6, the maximum value of the current is about 1.2mA, and a DI square wave signal is also output at the moment; when the states of the relay RL1 and the relay RL2 are other conditions, the optocoupler U1 is not conducted, and DI always outputs low level.

Fig. 2 is a flowchart of a method for detecting adhesion of a main relay of an ac pile of an electric vehicle according to an embodiment of the present invention. Referring to fig. 2, adopt above-mentioned electric automobile to exchange a main relay adhesion detecting system of stake, carry out electric automobile to exchange a main relay adhesion detection, specifically include the following operation:

1) when the adhesion detection of the relay is started, the analog detection module is in a closed state, the controller U3 firstly reads the output DI of the digital detection module, and the digital detection module is proved to be on if a periodic square wave signal is detected due to single-phase alternating current, so that the relay RL1 and the relay RL2 can be judged to be in a closed state; if the detected digital signal is always low level, it is proved that the digital detection module is not conducted, and the relay can have three states: only the relay RL1 is closed, only the relay RL2 is closed, or both the relay RL1 and the relay RL2 are in an open state;

2) then the controller U3 turns on the analog detection module with the DO output terminal at a high level, and since the analog detection module provides another path for the input terminal of the digital detection module after being connected, the state of the digital detection module may change; at this time, the controller U3 reads the output of the digital detection module again, and if the state of the digital detection module changes from non-conduction to conduction, it can be determined that the relay RL1 is in a closed state, and the relay RL2 is in an open state, that is, only the relay RL1 is closed; if the state of the digital detection circuit is not changed and still is not turned on, the relay RL1 can be judged to be in an off state, at this time, the controller U3 detects the voltage of the analog signal AI output by the analog detection module, and the on condition of the relay RL2 can be judged according to the detected analog voltage: if the relay RL2 is in a closed state, only the relay RL2 is closed; if the relay RL2 is in an off state, the relay RL1 and the relay RL2 are both in an off state;

3) after completely judging the states of the relay RL1 and the relay RL2, the controller U3 closes the simulation detection module and compares the result with the required state, and then the conclusion of whether the relay is stuck can be obtained.

In the above embodiments of the present invention, each part may be implemented by a hardware circuit, and certainly, the corresponding control function may also be implemented by software.

It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim concerned.

Furthermore, it should be understood that although the present description refers to embodiments, not every embodiment may contain only a single embodiment, and such description is for clarity only, and those skilled in the art should integrate the description, and the embodiments may be combined as appropriate to form other embodiments understood by those skilled in the art.