A detection system for an AC charging device and a method for detecting adhesion and short circuit

Abstract

The present invention belongs to the field of charging line detection, and particularly relates to a detection system for an AC charging device, as well as an adhesion detection and short-circuit detection method. It includes: a branch circuit with an auxiliary relay connected in series, which is led out from the output end of the live wire or the neutral wire in the charging line; a first coupling capacitor used to couple the branch circuit to the line segment between the input end of the live wire and the AC relay on the live wire; a first sampling resistor used to be connected in series between the output end of the AC relay on the live wire and the ground end; a current-limiting and voltage-limiting device used to be connected in series between the output end of the AC relay on the live wire and the first sampling resistor; a second sampling resistor used to be connected in series between the output end of the neutral wire in the charging line and the ground end, and a current-limiting and voltage-limiting device used to be connected in series between the output end of the neutral wire and the second sampling resistor; the high-potential ends of the first sampling resistor and the second sampling resistor are used as sampling ends for short-circuit detection between the live wire and the neutral wire and adhesion detection of the AC relay on the live wire.

Description

Technical Field

[0001] The present invention belongs to the field of charging line detection, and particularly relates to a detection system for an AC charging device, as well as a method for detecting adhesion and short circuit. Background Art

[0002] When an AC charging device (such as an AC charging pile) charges an electric vehicle, charging is achieved by controlling the closing of a relay. When charging stops, the relay is controlled to open to stop charging, ensuring reliable insulation between the charging interface circuit and the live circuit to meet safety requirements. However, due to device aging or other reasons, the relay may fail to open reliably, and the relay remains in an adhesive state for a long time. This adhesive state means that the contacts (switch part) of the relay are stuck due to long-term use or overload and cannot return to the initial state. This situation can cause the circuit to fail to open or close correctly, thus triggering a series of safety problems. In addition to the relay adhesion fault, before starting charging, the AC charging device must also ensure that there is no short-circuit fault at the output port, otherwise charging should not be started.

[0003] The mandatory national standards related to electric vehicle supply equipment are issued, requiring products such as AC charging devices to have the function of alarming and protecting when the relay is adhesively connected and when there is a short circuit at the output before charging, so as to ensure the safety of the equipment, vehicle, and personnel during the charging process. In summary, for the line detection of AC charging devices, the relay adhesion fault and the short-circuit fault need to be considered.

[0004] However, the existing relay adhesion detection and output short-circuit protection detection for charging devices usually use two independent circuits to implement their corresponding functions respectively. The relay adhesion detection usually needs to use an optocoupler or an operational amplifier to build a circuit to achieve it; the output short-circuit protection circuit is relatively complex, and a detection circuit is composed of an isolation transformer, or an isolated power supply, an optocoupler, an operational amplifier, or an auxiliary relay, etc. In fact, using this method not only makes the scheme complex and involves many components; but also has a high cost, which is not conducive to the design of small-volume integrated products. Summary of the Invention

[0005] The purpose of the present invention is to provide a detection system for an AC charging device, as well as a method for detecting adhesion and short circuit, which is used to solve the problems in the prior art that two independent detection circuits are used to implement the functions of relay adhesion detection and output short-circuit protection detection respectively, not only the scheme is complex and involves many components; but also the cost is high, which is not conducive to the design of small-volume integrated products.

[0006] To achieve the above object, the present invention provides a detection system for an AC charging device, the system comprising: a branch circuit led out from the output terminal of an AC relay on the live wire or the neutral wire of the charging circuit, in which an auxiliary relay is connected in series, the auxiliary relay is configured to disconnect when detecting the adhesion of the AC relay on the live wire and to close when detecting a short circuit between the live wire and the neutral wire, and a first coupling capacitor for coupling the branch circuit to a line segment between the input terminal of the live wire and the input terminal of the AC relay on the live wire;

[0007] The system further comprises a first sampling resistor connected in series between the output terminal of the AC relay on the live wire and the ground terminal, a current-limiting and voltage-limiting device for being connected in series between the output terminal of the AC relay on the live wire and the first sampling resistor, a second sampling resistor for being connected in series between the output terminal of the AC relay on the neutral wire of the charging circuit and the ground terminal, and a current-limiting and voltage-limiting device for being connected in series between the output terminal of the AC relay on the neutral wire and the second sampling resistor; the high-potential ends of the first sampling resistor and the second sampling resistor are both used as sampling terminals for detecting a short circuit between the live wire and the neutral wire and detecting the adhesion of the AC relay on the live wire;

[0008] The sampling terminal is configured to provide a voltage in a first reference state when the AC relay on the live wire should be disconnected and the auxiliary relay is disconnected, and the AC relay on the live wire is not adhered or adhered; the sampling terminal is further configured to provide a sampling voltage under the condition that the AC relay should be disconnected and the auxiliary relay is disconnected, and the difference between the sampling voltage and the first reference state is used to determine whether the AC relay on the live wire is adhered currently;

[0009] The sampling terminal is further configured to provide a voltage in a second reference state when the AC relay should be disconnected and the auxiliary relay is closed, and there is no short circuit or a short circuit between the live wire and the neutral wire; the sampling terminal is further configured to provide a sampling voltage under the condition that the AC relay on the live wire should be disconnected and the auxiliary relay is closed, and the difference between the sampling voltage and the second reference state is used to determine whether there is a short circuit between the live wire and the neutral wire currently.

[0010] Beneficial effects: The present invention provides a detection system for a new AC charging device. Through this system, it can be ensured that at least one auxiliary relay (this auxiliary relay is used to disconnect during the detection of the adhesion of the AC relay on the live wire and close during the detection of the short circuit between the live wire and the neutral wire), one coupling capacitor (i.e., the first coupling capacitor, this coupling capacitor is used to couple the branch with the auxiliary relay to the line segment between the input end of the live wire and the input end of the AC relay on the live wire, and can draw power from the live wire whether the relay is disconnected or not, so that the output end of this branch is energized), two sampling resistors (i.e., the sampling voltages output from the output ends of the live wire and the neutral wire are respectively obtained by using the sampling ends of the first sampling resistor and the second sampling resistor), and a current-limiting and voltage-limiting device (i.e., such a device is used to limit the current and voltage at the output end of the AC relay on the live wire, so as to achieve high-low voltage isolation on the basis of dividing the voltage of the first and second sampling resistors respectively). On this basis, detection circuits corresponding to adhesion detection and short-circuit detection and their corresponding detection logics are provided in the same circuit (that is, only the above-mentioned several devices are set in this system to basically achieve the above two detections). By performing corresponding control on this system (specifically, controlling the auxiliary relay to disconnect or close), it can be detected through this system whether the AC relay on the live wire is adhered and whether the live wire and the neutral wire are short-circuited.

[0011] Among them, the detection logic corresponding to the adhesion detection of the AC relay on the live wire by using this system is: the AC relay on the live wire is in the state of being supposed to be disconnected and the auxiliary relay is also in the disconnected state; if the above conditions are met, first obtain a first reference state (i.e., a reference voltage used as a reference, this first reference state may be the reference voltage corresponding to the non-adhesion state or the reference voltage corresponding to the adhesion state) from the sampling ends (i.e., the high-potential ends) of the first and second sampling resistors. In the case where this first reference state is the reference voltage corresponding to the non-adhesion state, after obtaining this first reference state, if the sampling voltage obtained (i.e., the sampling voltage obtained from the sampling end under the condition that the AC relay on the live wire is in the state of being supposed to be disconnected and the auxiliary relay is disconnected) is different from the first reference state (i.e., is inconsistent with the first reference state), it is determined that the AC relay on the live wire is adhered, otherwise it is determined that there is no adhesion. Similarly, in the case where this first reference state is the reference voltage corresponding to the adhesion state, after obtaining this first reference state, if the sampling voltage is different from the first reference state, it is determined that the AC relay on the live wire is not adhered, otherwise it is determined that there is adhesion.

[0012] Among them, the detection logic corresponding to the short-circuit detection between the live wire and the neutral wire of the system is as follows: The charging device is not in the charging state (at this time, the AC relay on the live wire is in the off state) and the auxiliary relay is in the closed state; if the above conditions are met, first obtain the second reference state (that is, a reference voltage used as a reference, and this second reference state may be the reference voltage corresponding to the short circuit between the live wire and the neutral wire, or it may be the reference voltage corresponding to the non-short circuit between the live wire and the neutral wire) from the sampling ends (i.e., the high-potential ends) of the first and second sampling resistors. In the case where the second reference state is the reference voltage corresponding to the short circuit between the live wire and the neutral wire, after obtaining this second reference state, if the sampled voltage obtained (that is, the sampled voltage obtained from the sampling end under the condition that the charging device is not in the charging state and the auxiliary relay is closed, note that the short-circuit detection must be before starting charging, that is, the charging device must not be in the charging state) is different from the second reference state (that is, not consistent with the second reference state), it is determined that there is no short circuit between the live wire and the neutral wire, otherwise it is determined that there is a short circuit between the live wire and the neutral wire. Similarly, in the case where the second reference state is the reference voltage corresponding to the non-short circuit between the live wire and the neutral wire, after obtaining this second reference state, if the sampled voltage obtained is different from the second reference state, it is determined that there is a short circuit between the live wire and the neutral wire, otherwise it is determined that there is no short circuit between the live wire and the neutral wire. In fact, when using this system for the above two detections, regardless of whether the first reference state is defined as the reference voltage corresponding to no adhesion or adhesion (as long as a reference voltage is defined), it is possible to determine whether the AC relay on the live wire is adhered according to the difference between the sampled voltage and it; and regardless of whether the second reference state is defined as the reference voltage corresponding to the short circuit between the live wire and the neutral wire or the non-short circuit between the live wire and the neutral wire (as long as a reference voltage is defined), it is possible to determine whether there is a short circuit between the live wire and the neutral wire according to the difference between the sampled voltage and it.

[0013] To sum up, the system can ensure that on the basis of detecting whether the AC relay on the live wire is adhered and detecting whether there is a short circuit between the live wire and the neutral wire in the same hardware circuit, it can also ensure that the schemes and hardware circuits for realizing the above two detections are relatively simple, involve fewer components, have lower costs, and are conducive to the design of small-volume integrated products.

[0014] Furthermore, a second coupling capacitor on the line segment between the input end for coupling the branch to the neutral wire and the input end of the AC relay on the neutral wire; the devices connected in series on the line between the output end of the AC relay on the live wire and the ground end and the parameters of the devices are the same as those of the devices connected in series on the line between the output end of the AC relay on the neutral wire and the ground end; the parameters of the second coupling capacitor are the same as those of the first coupling capacitor.

[0015] Further, a clamping circuit is used to respectively clamp and protect the voltage signals output by the first sampling resistor and the second sampling resistor, so as to clamp the voltage value of the voltage signal within the voltage range corresponding to the processing module.

[0016] Further, the current-limiting and voltage-limiting device connected in series between the output end of the AC relay on the live wire and the first sampling resistor includes a first isolation capacitor;

[0017] The current-limiting and voltage-limiting device connected in series between the output end of the AC relay on the neutral wire and the second sampling resistor includes a second isolation capacitor.

[0018] Further, the current-limiting and voltage-limiting device connected in series between the output end of the AC relay on the live wire and the first sampling resistor further includes: a first insulating resistor connected in series between the first isolation capacitor and the first sampling resistor;

[0019] The current-limiting and voltage-limiting device connected in series between the output end of the AC relay on the neutral wire and the second sampling resistor further includes: a second insulating resistor connected in series between the second isolation capacitor and the second sampling resistor.

[0020] The present invention also provides a method for detecting adhesion of an AC charging device. This method uses the above-mentioned detection system of the AC charging device. Under the condition that the AC relay on the live wire should be disconnected and the auxiliary relay is disconnected, according to the difference between the sampling voltages at the current first and second sampling resistors and the first reference state, it is determined whether the AC relay on the live wire is adhered at present; the first reference state is the voltage at the first and second sampling resistors when the AC relay on the live wire and the auxiliary relay are both disconnected and the AC relay on the live wire is not adhered or adhered.

[0021] Beneficial effects: The present invention provides a brand-new method for detecting adhesion of an AC charging device. The adhesion judgment logic adopted by this method is as follows: A condition is pre-constructed that the AC relay on the live wire should be disconnected and the auxiliary relay is disconnected. Under this condition, the voltages corresponding to the states when the relay is not adhered or adhered are respectively obtained at the first and second sampling resistors as the reference state; during formal detection, the AC relay on the live wire is closed to connect the corresponding branch to start the detection. The voltages respectively collected from the first and second sampling resistors when the AC relay on the live wire is in the state to be closed are compared with this reference state, and it is determined whether the above-mentioned relay is adhered according to the comparison difference (that is, it is determined whether it is adhered according to the similarity between the two. The greater the similarity, the more likely it is to be consistent with the previous state, that is, not adhered or adhered).

[0022] Further, the method for determining whether the AC relay on the live wire is stuck according to the difference between the sampling voltages at the current first and second sampling resistors and the first reference state includes:

[0023] If the first reference state is the voltages at the first and second sampling resistors when the AC relay on the live wire should be off and the auxiliary relay is off and the AC relay on the live wire is not stuck, then determine whether the AC relay on the live wire is stuck currently according to the difference between the difference value of the voltages at the first and second sampling resistors when not stuck and the difference value of the sampling voltages at the current first and second sampling resistors;

[0024] If the first reference state is the voltages at the first and second sampling resistors when the AC relay on the live wire should be off and the auxiliary relay is off and the AC relay on the live wire is stuck, then determine whether the AC relay on the live wire is stuck currently according to the difference between the difference value of the voltages at the first and second sampling resistors when stuck and the difference value of the sampling voltages at the current first and second sampling resistors.

[0025] The present invention also provides a short - circuit detection method for an AC charging device. This method uses the above - mentioned detection system of the AC charging device. Under the condition that the charging device is not in the charging state and the auxiliary relay is closed, determine whether there is a short - circuit between the current live wire and the neutral wire according to the difference between the sampling voltages at the current first and second sampling resistors and the second reference state; the second reference state is the voltages at the first and second sampling resistors when there is no short - circuit or a short - circuit between the live wire and the neutral wire under the condition that the charging device is not in the charging state and the auxiliary relay is closed.

[0026] Beneficial effects: The present invention provides a brand - new short - circuit detection method for an AC charging device. The short - circuit judgment logic adopted by this method is: create an environment in advance where the AC relay on the live wire is off and the auxiliary relay is closed. In this environment, obtain a state corresponding to the voltage at the first and second sampling resistors when the relay is not short - circuited or short - circuited as the reference state. During the formal detection, the charging device is still not in the charging state, the auxiliary relay is closed, and the corresponding branch is connected to start the detection. Compare the voltages collected from the first and second sampling resistors with this reference state, and determine whether there is a short - circuit according to the comparison difference (that is, determine whether there is a short - circuit according to the similarity between the two. The greater the similarity, the more likely it is to be consistent with the previous state, that is, no short - circuit or short - circuit).

[0027] Further, the method for determining whether there is a short - circuit between the current live wire and the neutral wire according to the difference between the sampling voltages at the current first and second sampling resistors and the second reference state includes:

[0028] If the second reference state is that the AC relay on the live wire is disconnected and the auxiliary relay is closed, and the voltages at the first and second sampling resistors when there is no short circuit between the live wire and the neutral wire, then, based on the difference between the difference value of the voltages at the first and second sampling resistors when there is no short circuit between the live wire and the neutral wire and the difference value of the sampled voltages at the current first and second sampling resistors, it is determined whether there is a short circuit between the current live wire and the neutral wire;

[0029] If the second reference state is that the AC relay on the live wire is disconnected and the auxiliary relay is closed, and the voltages at the first and second sampling resistors when there is a short circuit between the live wire and the neutral wire, then, based on the difference between the difference value of the voltages at the first and second sampling resistors when there is a short circuit between the live wire and the neutral wire and the difference value of the sampled voltages at the current first and second sampling resistors, it is determined whether there is a short circuit between the current live wire and the neutral wire. Description of the Drawings

[0030] Figure 1 It is a schematic diagram of the principle of the detection system of the AC charging device in the embodiment of the detection system of the AC charging device of the present invention. Detailed Embodiments

[0031] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the drawings and embodiments.

[0032] Embodiment of the Detection System of the AC Charging Device

[0033] This embodiment provides a technical solution for the detection system of the AC charging device. The main idea of this method is to provide a relatively simple hardware circuit (i.e., only using an auxiliary relay, a coupling capacitor and two sampling resistors), and different circuits set in this hardware circuit will be triggered during different detections, so as to realize two detections: (relay) adhesion detection and (charging line) short circuit detection.

[0034] Reference Figure 1 , the main components of this embodiment are: a detection circuit and an MCU (i.e., a processing module used to process the output of the detection circuit. In other embodiments, the MCU can also be replaced by other modules with data processing functions).

[0035] Among them, the detection circuit includes: a branch circuit in which an auxiliary relay K2 is serially arranged and led out from the output end (i.e., L_OUT or N_OUT) of the AC relay on the live wire or the neutral wire in the charging line, which is used to disconnect during the adhesion detection of the AC relay on the live wire and close during the short circuit detection between the live wire and the neutral wire Figure 1Only the branch led out from the output terminal of the AC relay on the live wire is shown herein (in other embodiments, this branch can also be connected to the output terminal of the AC relay on the neutral wire), and a line segment between the input end for coupling this branch to the live wire and the input end of the AC relay on the live wire (i.e., the line segment where L_IN and L_OUT are located), taking power from the live wire regardless of whether the AC relay on the live wire is disconnected, so as to have the output terminal of the led-out branch energized when the auxiliary relay is in the closed state, a first coupling capacitor C1. It further includes a first sampling resistor R1 connected in series between the output terminal of the AC relay on the live wire and the ground terminal, a current-limiting and voltage-limiting device connected in series between the output terminal of the AC relay on the live wire and the first sampling resistor, a second sampling resistor R3 connected in series between the output terminal of the neutral wire in the charging line and the ground terminal, and a current-limiting and voltage-limiting device connected in series between the output terminal of the neutral wire and the second sampling resistor (i.e., the second insulation resistor R7 and the second isolation capacitor C4).

[0036] The sampling terminals of the first sampling resistor R1 and the second sampling resistor R3 are both used to provide the voltage in the first reference state when the AC relay on the live wire should be disconnected and the auxiliary relay is disconnected, whether the AC relay K1 on the live wire is not stuck or is stuck (i.e., a reference voltage used as a reference); it is also used to provide the sampling voltage under the condition that the AC relay on the live wire should be disconnected and the auxiliary relay is disconnected, and the difference between this sampling voltage and the first reference state is used to determine whether the AC relay on the current live wire is stuck.

[0037] The sampling terminals of the first sampling resistor R1 and the second sampling resistor R3 are also used to provide the voltage in the second reference state when the AC relay on the live wire should be disconnected and the auxiliary relay is closed, whether there is a short circuit or not between the live wire and the neutral wire (i.e., a reference voltage used as a reference); it is also used to provide the sampling voltage under the condition that the charging device is not in the charging state and the auxiliary relay is closed, and the difference between this sampling voltage and the second reference state is used to determine whether there is a short circuit between the current live wire and the neutral wire. Specifically, the current-limiting and voltage-limiting device connected in series between the output terminal L_OUT of the AC relay on the live wire and the first sampling resistor R1 includes: a first isolation capacitor C3 for connecting the output terminal L_OUT of the AC relay on the live wire and the first insulation resistor R6; the current-limiting and voltage-limiting device connected in series between the output terminal N_OUT of the neutral wire and the second sampling resistor R3 includes: a second isolation capacitor C4 for connecting the output terminal N_OUT of the neutral wire and the second insulation resistor R3. In this embodiment, both C3 and C4 used are high-voltage isolation capacitors, and setting C3 and C4 can achieve the effect of high-voltage and low-voltage isolation.

[0038] The current-limiting and voltage-limiting device connected in series between the output terminal L_OUT of the AC relay on the live wire and the first sampling resistor R1 further includes: a first insulation resistor R6 connected in series between the first isolation capacitor C3 and the first sampling resistor R1;

[0039] The current-limiting and voltage-limiting device connected in series between the output terminal N_OUT of the neutral wire and the second sampling resistor R3 further includes: a second insulation resistor R7 connected in series between the second isolation capacitor C4 and the second sampling resistor R3. In this embodiment, R6 and R7 adopted are both presented in the form of several resistors connected in series in the actual circuit to enhance insulation. In other embodiments, any number of insulation resistors can be adopted.

[0040] In addition to the above components, the system further includes: a second coupling capacitor C2 for coupling the above branch to the neutral wire (the parameters of this coupling capacitor are the same as those of the first coupling capacitor, and the coupling capacitors adopted are all safety capacitors. The reason for adopting safety capacitors is that C1 and C2 are connected in series between the live wire L and the neutral wire N. If general capacitors are adopted, the consequences of failure are relatively serious); the devices connected in series on the line between the output terminal L_OUT of the AC relay on the live wire and the ground terminal and the parameters of the devices are the same as those of the devices connected in series on the line between the output terminal N_OUT of the AC relay on the neutral wire and the ground terminal. In this embodiment, the devices and their parameters adopted are the same to make the circuit of the system symmetrical up and down, so as to ensure that when technicians misoperate and reverse the live wire and the neutral wire during actual application, a reasonable loop can still be provided to realize adhesion detection and short-circuit detection. In other embodiments, if the reverse connection of the live wire and the neutral wire is not considered, C2 may not be set, and only C1 and K2 are retained to also realize the detection function. Theoretically, in this case, the value of the output voltage signal will double, but the overall detection logic will not change (that is, it only affects the magnitude of the output signal and does not affect the detection logic). The specific influence of whether to set C2 on the output voltage signal is as follows: if C2 is set, the voltage between C1 and C2 is half of the mains voltage, and this voltage forms a loop through the K2 relay and the subsequent circuit; if C2 is not set, the voltage at the left end of K2 is the mains voltage, and it can also form a loop through the K2 relay and the subsequent circuit.

[0041] Specifically, by using the circuit provided by the system and combining the corresponding judgment logic, the adhesion detection of the AC relay K1 on the live wire (i.e., determining whether K1 is adhered) and the short-circuit detection of the charging wire (i.e., determining whether there is a short circuit between the live wire L and the neutral wire N) can be achieved. The MCU stores the judgment logic corresponding to the adhesion detection and the short-circuit detection respectively. The detection module performs the detection corresponding to the instruction according to the instruction it receives. If the instruction corresponding to the adhesion detection is received, the adhesion detection of the AC relay K1 on the live wire can be achieved according to the judgment logic corresponding to the adhesion detection in the MCU; if the instruction corresponding to the short-circuit detection is received, the short-circuit detection of the charging wire (i.e., determining whether there is a short circuit between the live wire L and the neutral wire N) can be achieved according to the judgment logic corresponding to the short-circuit detection in the MCU. In this embodiment, taking an AC charging device as a certain AC charging pile as an example (in other embodiments, the AC charging device can also be other devices used to charge other devices), the above-mentioned adhesion detection and short-circuit detection and their corresponding judgment logics are as follows:

[0042] I) Adhesion detection of the AC charging device (i.e., AC charging pile) (i.e., adhesion detection)

[0043] The detection object (i.e., the test sample) of this detection is the AC relay K1 on the live wire. The judgment logic adopted for this detection is: under the condition that the AC relay on the live wire should be disconnected (the AC relay on the live wire should be disconnected means that the AC relay is in a situation where it should be disconnected or should not be closed, and in this situation, the charging pile will correspondingly issue corresponding instructions to disconnect K1 and K3) and the auxiliary relay K2 is disconnected, judge whether the AC relay on the current live wire is adhered according to the difference between the sampling voltages at the current first and second sampling resistors (i.e., at R1 and R3) and the first reference state. The first reference state is the voltage at the first and second sampling resistors when K1 is not adhered or adhered under the condition that the AC relay K1 on the live wire and the auxiliary relay K2 are both disconnected. It can be seen that the auxiliary relay K2 is used to disconnect when the AC relay on the live wire should be disconnected and the adhesion detection of the AC charging pile needs to be performed (especially when the charging pile correspondingly issues corresponding instructions to disconnect K1 and K3, that is, when the charging pile stops charging) to perform the adhesion detection of the AC charging pile.

[0044] Specifically, in this embodiment, this first reference state means: the state corresponding to the difference Vth1 between the voltage reference value collected at the first sampling resistor R1 and the voltage reference value collected at the second sampling resistor R3 under the condition that K1 and K2 are both disconnected in advance, that is, the voltage at the first and second sampling resistors when K1 is not adhered. After obtaining the first reference state, if K1 is adhered during the adhesion detection, it will cause the loop including L_IN, K1, L_OUT, C3, R6, R1, and PE to be connected, resulting in an obvious difference in the voltage at R1 at this time compared with the first reference state.

[0045] Therefore, when performing adhesion detection, the sampling voltage Vz1 at the current first sampling resistor R1 and the sampling voltage Vz2 at the second sampling resistor R3 are obtained; subsequently, by comparing the difference between |Vz1 - Vz2| and Vth1, it can be determined whether K1 is in an adhered state; that is, the smaller this difference is, the closer the states corresponding to Vz1 and Vz2 are to the first reference state. In this embodiment, Vth1 represents the voltage difference between the first sampling resistor R1 and the second sampling resistor R3 when no adhesion occurs. If the difference between the voltage difference between R1 and R3 when no adhesion occurs and the current voltage difference between R1 and R3 is smaller, it means that the current states corresponding to Vz1 and Vz2 are closer to the state where K1 is not adhered.

[0046] After obtaining the above parameters, the method for determining whether the AC relay on the live wire is adhered currently according to the difference between the sampling voltages at the current R1 and R3 and the first reference state includes:

[0047] If the first reference state is the voltages at the first and second sampling resistors when the AC relay on the live wire should be disconnected and the auxiliary relay is disconnected and no adhesion occurs on the AC relay on the live wire, then according to the difference between the difference value of the voltages at the first and second sampling resistors when no adhesion occurs and the difference value of the sampling voltages at the current first and second sampling resistors, it is determined whether the AC relay on the live wire is adhered currently.

[0048] Specifically, considering the errors in the sampling voltages Vz1 and Vz2 at the first and second sampling resistors, the tolerance threshold Vth2 is determined according to experience. According to the superposition result obtained by superimposing Vth1 and the tolerance threshold Vth2 (the upper limit value of the tolerance threshold is the positive tolerance value +Vth2, and the lower limit value is the negative tolerance value -Vth2), the upper limit value and the lower limit value of the first threshold range are obtained, that is, the upper limit value is Vth1 + Vth2, and the lower limit value is Vth1 - Vth2. Then there are the following judgments:

[0049] If Vth1 - Vth2 < |Vz1 - Vz2| < Vth1 + Vth2, it means that the difference value (i.e., the difference value |Vz1 - Vz2| between Vz1 and Vz2) does not exceed the threshold range after Vth1 is superimposed with the positive and negative tolerance thresholds Vth2. Then it shows that the difference value is close to Vth1, and further it can be shown that the states corresponding to Vz1 and Vz2 are close to the state corresponding to Vth1. According to this expression, it can be judged that the AC relay K1 on the current live wire has not adhered. This expression is equivalent to saying that when there is no adhesion, the difference value of the voltages at the first and second sampling resistors (i.e., |Vz1 - Vz2|) is greater than or equal to the set tolerance threshold Vth2 compared with the difference value of the sampling voltages at the current first and second sampling resistors (i.e., Vth1), then it is determined that the AC relay on the current live wire has adhered, and if it is less, it is determined that the AC relay on the current live wire has not adhered.

[0050] In addition, usually the connection between the live wire and the neutral wire is normal, and the reverse connection of the live wire and the neutral wire is actually a special situation caused by operation errors. When the connection between the live wire and the neutral wire is normal, since there is almost no voltage on the neutral wire under normal circumstances, this system can only judge the adhesion of the live wire and cannot judge whether the neutral wire relay adheres (and in the circuit provided by this system, whether the neutral wire relay adheres has no effect on the output voltage signal, that is, regardless of whether the neutral wire relay adheres, the finally output voltage signal can only characterize the state of the live wire relay). In the case of reverse connection of the live wire and the neutral wire, the live wire recognized by the operator (i.e., the technician) is actually the neutral wire, and the neutral wire recognized by the operator is actually the live wire. Therefore, the "neutral wire relay" in the operator's cognition is actually the real live wire relay, and finally the adhesion situation of the (real) live wire relay is still detected. And in actual engineering, since there are real voltage and current on the live wire, it is only necessary to judge whether the live wire relay adheres.

[0051] In other embodiments, Vth1 can also represent the difference between the voltage at the first sampling resistor R1 and the voltage at the second sampling resistor R3 when adhesion occurs. Then, similar to the case where Vth1 represents the difference between the voltage at R1 and the voltage at the second sampling resistor R3 when there is no adhesion, if the first reference state is the voltages at the first and second sampling resistors when the AC relay on the live wire adheres under the condition that the AC relay on the live wire should be disconnected and the auxiliary relay is disconnected, then according to the difference between the difference value of the voltages at the first and second sampling resistors when adhesion occurs and the difference value of the sampling voltages at the current first and second sampling resistors, it is judged whether the AC relay on the current live wire adheres. Specifically, in this case, it can be judged whether the AC relay K1 on the current live wire adheres according to the expression Vth1 - Vth2 < |Vz1 - Vz2| < Vth1 + Vth2, that is, if this expression is satisfied, it is judged that K1 adheres.

[0052] (II) Short-circuit Detection of AC Charging Equipment (i.e., AC Charging Pile)

[0053] The object of this detection (i.e., the test sample) is the charging line (i.e., the live wire L and the neutral wire N). In this embodiment, the judgment logic adopted in this detection is as follows: when the charging pile is not in the charging state (i.e., both K1 and K3 are in the off state. It should be noted that this short-circuit detection must be completed when the charging pile is not in the charging state, that is, when the live wire is not powered on. Usually, the adhesion detection is mainly carried out when the AC charging pile completes charging and issues the command to disconnect K1 and K3. As long as it is determined that there is no adhesion, before the next charging of the charging pile, it can be defaulted that the charging pile is not in the charging state, which is equivalent to both K1 and K3 being in the off state) and the auxiliary relay K2 is closed, judge whether there is a short circuit between the current live wire and the neutral wire according to the difference between the sampling voltage Vd1 at the first sampling resistor, the sampling voltage Vd2 at the second sampling resistor and the second reference state; the second reference state is the voltage at the first and second sampling resistors when there is no short circuit or a short circuit between the live wire and the neutral wire under the condition that the charging pile is not in the charging state and the auxiliary relay is closed. It can be seen that the auxiliary relay is used to close when the charging pile is not in the charging state and short-circuit detection of the AC charging pile is required (this detection is usually real-time detection when the charging pile is not in the charging state, that is, real-time detection when both K1 and K3 are in the off state), so as to couple the voltage on the live wire to the output end of the AC relay on the live wire or the output end of the AC relay on the neutral wire to perform adhesion detection of the AC charging pile.

[0054] Specifically, on the basis of closing K2 in this short-circuit detection, if a short circuit occurs, the loop of L_IN, C1, K2, R6 and R1 will be connected; if no short circuit occurs, the loop containing L_IN, C1, K2, N_OUT, C4, R7 and R3 will be connected.

[0055] And the above-mentioned second reference state means: the state corresponding to the difference Vth3 between the voltage reference value collected at R1 and the voltage reference value collected at R3 under the condition that K1 is off and K2 is closed in advance. In this embodiment, Vth3 represents the difference between the voltage at the first sampling resistor R1 when there is no short circuit and the voltage at the second sampling resistor R3 when there is no short circuit. The smaller the difference between Vth3 and |Vd1 - Vd2|, the closer the states corresponding to Vd1 and Vd2 are to the state of no short circuit between the live wire and the neutral wire.

[0056] Subsequently, by comparing the difference between Vd1 and Vd2 with the difference of Vth3, it can be determined whether there is a short circuit between the live wire and the neutral wire; that is, the smaller the difference, the closer the states corresponding to Vd1 and Vd2 are to the second reference state. In this embodiment, Vth3 represents the voltage difference between the first sampling resistor R1 and the second sampling resistor R3 when there is no short circuit; in this case, the smaller the difference, the closer the states corresponding to Vd1 and Vd2 are to the state without a short circuit between the live wire and the neutral wire. In this embodiment, the method for determining whether there is a short circuit between the current live wire and the neutral wire according to the difference between the sampling voltages at the current first and second sampling resistors and the second reference state includes:

[0057] If the second reference state is the voltages at the first and second sampling resistors when there is no short circuit between the live wire and the neutral wire under the condition that the AC relay on the live wire is off and the auxiliary relay is on, then according to the difference between the difference value of the voltages at the first and second sampling resistors when there is no short circuit between the live wire and the neutral wire and the difference value of the sampling voltages at the current first and second sampling resistors, it is determined whether there is a short circuit between the current live wire and the neutral wire.

[0058] If the second reference state is the voltages at the first and second sampling resistors when there is a short circuit between the live wire and the neutral wire under the condition that the AC relay on the live wire is off and the auxiliary relay is on, then according to the difference between the difference value of the voltages at the first and second sampling resistors when there is a short circuit between the live wire and the neutral wire and the difference value of the sampling voltages at the current first and second sampling resistors, it is determined whether there is a short circuit between the current live wire and the neutral wire.

[0059] Similar to the adhesion detection, considering the errors in the sampling voltages Vd1 and Vd2 at the first and second sampling resistors, the tolerance threshold Vth4 is determined according to experience. According to the superimposed result of Vth3 and the tolerance threshold Vth4 (the upper limit value of this tolerance threshold is the positive tolerance value +Vth4, and the lower limit value is the negative tolerance value -Vth4), the upper limit value and the lower limit value of the second threshold range are obtained, that is, the upper limit value is Vth3 + Vth4, and the lower limit value is Vth3 - Vth4. Then there are the following judgments:

[0060] If Vth3 - Vth4 < |Vd1 - Vd2| < Vth3 + Vth4 is satisfied, it means that the difference value (i.e., the difference value |Vd1 - Vd2| between Vd1 and Vd2) does not exceed the threshold range (i.e., the second threshold range) after Vth3 is superimposed with the positive and negative tolerance thresholds Vth4. Then it shows that the difference value is close to Vth3, and further it can be shown that the states corresponding to Vd1 and Vd2 are close to the state corresponding to Vth3. According to this expression, it can be judged whether there is no short circuit between the current live wire and the neutral wire. This expression is equivalent to saying that when there is no short circuit between the live wire and the neutral wire, the difference value of the voltages at the first and second sampling resistors (i.e., |Vd1 - Vd2|) is greater than the set tolerance threshold Vth4 compared with the difference value of the sampling voltages at the current first and second sampling resistors (i.e., Vth3), then it is determined that there is a short circuit between the live wire and the neutral wire of the current charging line.

[0061] In other embodiments, Vth3 can also represent the difference between the voltage at the first sampling resistor R1 and the voltage at the second sampling resistor R3 when there is a short circuit between the live wire and the neutral wire. Then, similar to the case where Vth3 represents the difference between the voltage at R1 and the voltage at the second sampling resistor R3 when there is no short circuit between the live wire and the neutral wire, if the second reference state is the condition that the AC relay on the live wire is off and the auxiliary relay is on, and the voltages at the first and second sampling resistors when there is a short circuit between the live wire and the neutral wire, then according to the difference between the difference value of the voltages at the first and second sampling resistors during the short circuit and the difference value of the sampling voltages at the current first and second sampling resistors, it is judged whether there is a short circuit between the current live wire and the neutral wire. Specifically, in this case, it can be judged whether there is a short circuit between the current live wire and the neutral wire according to the expression Vth3 - Vth4 < |Vd1 - Vd2| < Vth3 + Vth4, that is, if this expression is satisfied, it is judged that there is a short circuit between the live wire and the neutral wire.

[0062] In this embodiment, using differential operation for adhesion detection and short - circuit detection is beneficial to reducing the influence of errors such as component parameters of two symmetric circuits and common - mode interference signals, and is also beneficial to subsequent processing and determination of the output of the detection module. However, not performing differential operation does not affect the logic of this method. Therefore, in other embodiments, differential operation may not be performed either, and the voltages at the first and second sampling resistors obtained can be directly compared.

[0063] In this embodiment, the detection module further includes: a clamping circuit (i.e., clamping diodes D1 and D2) for respectively clamping and protecting the voltage signals output by the first sampling resistor and the second sampling resistor to clamp the voltage value of the voltage signal within the rated voltage range (i.e., 0V~VCC) corresponding to the used processing module. In other embodiments, if the processing module for processing the output of the detection module is provided with a clamping protection device, D1 and D2 may not be provided in the detection module either.

[0064] Embodiment of the adhesion detection method for AC charging equipment

[0065] This embodiment provides a technical solution for the adhesion detection method of an AC charging equipment. In this embodiment, the detection system of the AC charging equipment in the detection system embodiment of the AC charging equipment is adopted to implement the adhesion detection method of the AC charging equipment.

[0066] Since the specific working mode and working principle of the adhesion detection method of the AC charging equipment in this embodiment have been described in detail in the above-mentioned detection system embodiment of the AC charging equipment, they will not be elaborated here.

[0067] Embodiment of the short - circuit detection method for AC charging equipment

[0068] This embodiment provides a technical solution for the short - circuit detection method of an AC charging equipment. In this embodiment, the detection system of the AC charging equipment in the detection system embodiment of the AC charging equipment is adopted to implement the short - circuit detection method of the AC charging equipment.

[0069] Since the specific working mode and working principle of the short - circuit detection method of the AC charging equipment in this embodiment have been described in detail in the above - mentioned detection system embodiment of the AC charging equipment, they will not be elaborated here.

[0070] It should be understood that the above - mentioned specific embodiments of the present invention are only used for exemplary illustration or explanation of the principle of the present invention, and do not constitute a limitation to the present invention.

Claims

1. A detection system for an AC charging device, characterized in that, Including: A branch circuit that is led out from the output terminal of the AC relay on the live wire or the neutral wire of the charging circuit and is serially provided with an auxiliary relay for disconnecting during the adhesion detection of the AC relay on the live wire and closing during the short - circuit detection between the live wire and the neutral wire, and a first coupling capacitor on the line segment for coupling the branch circuit to the line between the input terminal of the live wire and the input terminal of the AC relay on the live wire; It also includes a first sampling resistor serially connected between the output terminal of the AC relay on the live wire and the ground terminal, a current - limiting and voltage - limiting device for being serially connected between the output terminal of the AC relay on the live wire and the first sampling resistor, a second sampling resistor for being serially connected between the output terminal of the AC relay on the neutral wire of the charging circuit and the ground terminal, and a current - limiting and voltage - limiting device for being serially connected between the output terminal of the AC relay on the neutral wire and the second sampling resistor; the high - potential ends of the first sampling resistor and the second sampling resistor are both used as sampling terminals for the short - circuit detection between the live wire and the neutral wire and the adhesion detection of the AC relay on the live wire; The sampling terminal is used to provide the voltage in the first reference state when the AC relay on the live wire should be disconnected and the auxiliary relay is disconnected, and the AC relay on the live wire does not have adhesion or has adhesion; it is also used to provide a sampling voltage under the condition that the AC relay should be disconnected and the auxiliary relay is disconnected, and the difference between this sampling voltage and the first reference state is used to determine whether the AC relay on the current live wire has adhesion; The sampling terminal is also used to provide the voltage in the second reference state when the AC relay should be disconnected and the auxiliary relay is closed, and the live wire and the neutral wire are not short - circuited or are short - circuited; it is also used to provide a sampling voltage under the condition that the AC relay on the live wire should be disconnected and the auxiliary relay is closed, and the difference between this sampling voltage and the second reference state is used to determine whether the current live wire and the neutral wire are short - circuited.

2. The detection system for AC charging equipment according to claim 1, characterized in that: A second coupling capacitor on the line segment for coupling the branch circuit to the line between the input terminal of the neutral wire and the input terminal of the AC relay on the neutral wire; the devices serially connected on the line between the output terminal of the AC relay on the live wire and the ground terminal and the parameters of the devices are the same as those of the devices serially connected on the line between the output terminal of the AC relay on the neutral wire and the ground terminal; The parameters of the second coupling capacitor are the same as those of the first coupling capacitor.

3. The detection system of the AC charging device according to claim 1, characterized in that, A clamping circuit for respectively clamping and protecting the voltage signals output by the first sampling resistor and the second sampling resistor to clamp the voltage value of the voltage signal within the corresponding voltage range of the processing module.

4. The detection system for AC charging equipment according to any one of claims 1 to 3, characterized in that: The current - limiting and voltage - limiting device for being serially connected between the output terminal of the AC relay on the live wire and the first sampling resistor includes a first isolation capacitor; The current - limiting and voltage - limiting device for being serially connected between the output terminal of the AC relay on the neutral wire and the second sampling resistor includes a second isolation capacitor.

5. The detection system of the AC charging device according to claim 4, characterized in that The current - limiting and voltage - limiting device for being serially connected between the output terminal of the AC relay on the live wire and the first sampling resistor further includes: a first insulating resistor serially connected between the first isolation capacitor and the first sampling resistor; The current-limiting and voltage-limiting device connected in series between the output terminal of the AC relay on the neutral line and the second sampling resistor further includes: a second insulation resistor connected in series between the second isolation capacitor and the second sampling resistor.

6. A method for detecting adhesion of an AC charging device, characterized in that: Using the detection system of the AC charging device according to any one of claims 1-5, under the condition that the AC relay on the live wire should be disconnected and the auxiliary relay is disconnected, judge whether the AC relay on the current live wire is stuck according to the difference between the sampling voltages at the current first and second sampling resistors and the first reference state; The first reference state is the voltages at the first and second sampling resistors when the AC relay on the live wire is not stuck or is stuck under the condition that the AC relay and the auxiliary relay on the live wire are both disconnected.

7. The adhesion detection method of the AC charging device according to claim 6, wherein, The method of judging whether the AC relay on the current live wire is stuck according to the difference between the sampling voltages at the current first and second sampling resistors and the first reference state includes: If the first reference state is the voltages at the first and second sampling resistors when the AC relay on the live wire is not stuck under the condition that the AC relay on the live wire should be disconnected and the auxiliary relay is disconnected, then judge whether the AC relay on the current live wire is stuck according to the difference between the difference value of the voltages at the first and second sampling resistors when not stuck and the difference value of the sampling voltages at the current first and second sampling resistors; If the first reference state is the voltages at the first and second sampling resistors when the AC relay on the live wire is stuck under the condition that the AC relay on the live wire should be disconnected and the auxiliary relay is disconnected, then judge whether the AC relay on the current live wire is stuck according to the difference between the difference value of the voltages at the first and second sampling resistors when stuck and the difference value of the sampling voltages at the current first and second sampling resistors.

8. A short - circuit detection method for an AC charging device, characterized in that, Using the detection system of the AC charging device according to any one of claims 1-5, under the condition that the charging device is not in the charging state and the auxiliary relay is closed, judge whether there is a short circuit between the current live wire and the neutral line according to the difference between the sampling voltages at the current first and second sampling resistors and the second reference state; The second reference state is the voltages at the first and second sampling resistors when there is no short circuit or a short circuit between the live wire and the neutral line under the condition that the charging device is not in the charging state and the auxiliary relay is closed.

9. The short-circuit detection method of the AC charging device according to claim 8, characterized in that, The method of judging whether there is a short circuit between the current live wire and the neutral line according to the difference between the sampling voltages at the current first and second sampling resistors and the second reference state includes: If the second reference state is the voltages at the first and second sampling resistors when there is no short circuit between the live wire and the neutral line under the condition that the AC relay on the live wire is disconnected and the auxiliary relay is closed, then judge whether there is a short circuit between the current live wire and the neutral line according to the difference between the difference value of the voltages at the first and second sampling resistors when there is no short circuit between the live wire and the neutral line and the difference value of the sampling voltages at the current first and second sampling resistors; If it is under the condition that the AC relay on the live wire is disconnected and the auxiliary relay is closed in the second reference state, the voltages at the first and second sampling resistors when a short circuit occurs between the live wire and the neutral wire, then according to the difference between the difference value of the voltages at the first and second sampling resistors when a short circuit occurs between the live wire and the neutral wire and the difference value of the sampled voltages at the current first and second sampling resistors, it is determined whether a short circuit occurs between the current live wire and the neutral wire.

Images