Power switch contact sticking detection circuit and alternating current charging pile charging system

Abstract

The utility model provides a kind of power switch contact sticking detection circuit and alternating current charging pile charging system, by detecting the first level signal output by contact voltage detection unit and the second level signal output by charging current detection unit, the corresponding fault state indicating signal is output, to indicate different types of contact sticking fault, including contact complete sticking fault and contact virtual sticking fault, to form multi-parameter linkage fault detection mechanism, the accuracy and reliability of contact sticking detection can be effectively improved;The utility model also provides a kind of alternating current charging pile charging system, one or more power switch sticking detection circuits are used above respectively to one or more power switch units in alternating current charging pile charging circuit for contact sticking detection, to ensure the charging safety of alternating current charging pile charging circuit.

Description

Technical Field

[0001] This utility model relates to the field of relay contact adhesion detection technology, and in particular to a power switch contact adhesion detection circuit and an AC charging pile charging system. Background Technology

[0002] As a core infrastructure for electric vehicle energy replenishment, AC charging piles operate on the principle of supplying AC power from the power grid to the on-board charger of the electric vehicle via a charging interface. The on-board charger then converts the AC power to DC power to charge the electric vehicle's battery. The power transmission circuit of the AC charging pile, also known as the AC charging circuit, is used to transmit AC power from the power grid to the charging interface. It relies on contact-type power switches such as relays and contactors to achieve physical on / off control.

[0003] Relays, contactors, and other contact-type power switches are prone to contact sticking faults after long-term use. This can lead to the inability to properly control the charging process of AC charging piles, affecting the user experience. More importantly, it can cause the power to remain on even after charging is completed, leaving the charging interface energized for an extended period, increasing the risk of electric shock. It can also potentially cause a short circuit in the power transmission circuit of the AC charging pile, damaging the charging equipment and electric vehicles. Furthermore, the heat generated by electric shock may even cause a fire, resulting in a more serious safety accident.

[0004] Existing relay / contactor contact sticking detection circuits can only identify "completely stuck contact faults" where contacts are continuously conducting, but cannot promptly identify "loosely stuck contact faults" where contacts are not making proper contact. Therefore, the accuracy of contact sticking fault detection results is poor. Furthermore, existing relay / contactor contact sticking detection circuits often use optocouplers for signal amplification or isolation. However, the current transfer ratio (CTR) of optocouplers is easily affected by factors such as input current magnitude, ambient temperature, and aging over time, leading to unstable signal amplification or isolation accuracy and consequently, poor reliability of contact sticking fault detection results. Utility Model Content

[0005] In view of the shortcomings of the prior art described above, the purpose of this utility model is to provide a power switch contact adhesion detection circuit and an AC charging pile charging system to solve the technical problems of poor detection accuracy, poor reliability and lack of contact adhesion fault detection in the existing relay / contactor contact adhesion detection circuit.

[0006] To achieve the above and other related objectives, the first aspect of this utility model provides a power switch contact adhesion detection circuit for detecting contact adhesion in a power switch unit of an AC charging pile charging circuit. The power switch unit includes a power switch and a driving circuit for the power switch. The power switch includes a moving contact, a stationary contact, and an electromagnetic coil. The output terminal of the driving circuit is electrically connected to the electromagnetic coil. The power switch contact adhesion detection circuit includes a contact voltage detection unit, which includes an enable control circuit and a contact voltage detection circuit. The contact voltage detection circuit is electrically connected to the moving contact and the stationary contact via the enable control circuit. The enable control circuit controls the on / off state of the contact voltage detection circuit. The contact voltage detection circuit is used to control the on / off state of the contact voltage detection circuit when the enable control circuit... When the circuit is open, a first-level signal related to the voltage difference between the moving contact and the stationary contact is output; a charging current detection unit, comprising: a charging current detection circuit; the charging current detection circuit is electrically connected to the output terminal of the power switch, for outputting a second-level signal related to the magnitude of the charging current flowing out of the power switch; a main control unit, the main control unit being electrically connected to the drive circuit, the enable control circuit, the contact voltage detection circuit, and the charging current detection circuit respectively, the main control unit being configured to: output control signals to the drive circuit and the enable control circuit to turn on or off; receive the first-level signal and the second-level signal, and output a fault status indication signal when the first-level signal and / or the second-level signal indicates an abnormality.

[0007] In some embodiments of the first aspect of this utility model, the enable control circuit includes: a silicon controlled rectifier (SCR) chip, wherein a first pin of the SCR chip is electrically connected to the main control unit, and a second pin and a third pin are electrically connected to the moving contact and the contact voltage detection circuit, respectively, and is configured to: after receiving a start detection control signal from the main control unit at the first pin, close the second pin and the third pin to output a high-level enable signal to control the contact voltage detection circuit to conduct; and after receiving an end detection control signal from the main control unit at the first pin, open the second pin and the third pin to output a low-level enable signal to control the contact voltage detection circuit to disconnect.

[0008] In some embodiments of the first aspect of this utility model, the contact voltage detection circuit includes: a first operational amplifier, wherein the non-inverting input terminal of the first operational amplifier is electrically connected to the moving contact through the thyristor chip, the inverting input terminal is electrically connected to the stationary contact, and the output terminal is electrically connected to the main control unit, for differentially amplifying the voltage difference between the moving contact and the stationary contact when the contact voltage detection circuit is turned on, and outputting the first level signal to the main control unit.

[0009] In some embodiments of the first aspect of this utility model, the charging current detection circuit includes: a current sensor, the two input terminals of the current sensor being electrically connected to the circuit of the output terminal of the power switch, and the output terminal being electrically connected to the main control unit, for detecting whether there is current output at the output terminal of the power switch, and outputting the second level signal to the main control unit.

[0010] In some embodiments of the first aspect of this utility model, the main control unit is specifically configured to: output a first fault state indication signal when the first level signal indicates that there is a first type of abnormal voltage difference between the moving contact and the stationary contact, and the second level signal indicates that there is a first type of abnormal current in the charging current flowing into the AC charging pile charging circuit; output a second fault state indication signal when the first level signal indicates that there is a second type of abnormal voltage difference between the moving contact and the stationary contact, and the second level signal indicates that there is a second type of abnormal current in the charging current flowing into the AC charging pile charging circuit; otherwise, output a normal state indication signal.

[0011] In some embodiments of the first aspect of this utility model, the power switch contact adhesion detection circuit further includes: an electromagnetic coil drive signal detection unit, the electromagnetic coil drive signal detection unit including: an electromagnetic coil drive signal detection circuit; the electromagnetic coil drive signal detection circuit is electrically connected between the output terminal of the drive circuit and the electromagnetic coil, and is electrically connected to the main control unit, for outputting a third level signal related to the electromagnetic coil drive voltage signal flowing into the power switch to the main control unit when the drive circuit is turned on, so that the main control unit outputs a third fault status indication signal when the third level signal indicates that the electromagnetic coil drive voltage signal flowing into the power switch is abnormal.

[0012] In some embodiments of the first aspect of this utility model, the electromagnetic coil drive signal detection circuit includes: a second operational amplifier, the non-inverting input terminal of the second operational amplifier being electrically connected between the output terminal of the drive circuit and the electromagnetic coil, and the inverting input terminal being electrically connected to its output terminal; and a third operational amplifier, the non-inverting input terminal of the third operational amplifier being electrically connected to the output terminal of the second operational amplifier, the inverting input terminal being electrically connected to its output terminal, and electrically connected to the main control unit.

[0013] In some embodiments of the first aspect of this utility model, the power switch contact adhesion detection circuit further includes: a power switch specification detection unit, which is electrically connected to the AC charging pile charging circuit and electrically connected to the main control unit, for outputting a fourth level signal related to the standard charging current of the AC charging pile charging circuit to the main control unit, so that the main control unit outputs a fourth fault status indication signal when the fourth level signal is inconsistent with the second level signal.

[0014] In some embodiments of the first aspect of this utility model, the power switch contact adhesion detection circuit further includes: a fault execution unit, which is electrically connected to the main control unit and to the AC charging pile charging circuit, and is used to perform an alarm operation and output a control signal to disconnect the AC charging pile charging circuit upon receiving a fault status indication signal from the main control unit.

[0015] To achieve the above and other related objectives, a second aspect of this utility model provides an AC charging pile charging system, comprising: an AC charging pile, the AC charging pile including: an AC charging pile charging circuit; the AC charging pile charging circuit including one or more power switching units; wherein, the power switching unit includes: a power switch and a driving circuit for the power switch; the power switch including: a moving contact, a stationary contact and an electromagnetic coil; the output terminal of the driving circuit is electrically connected to the electromagnetic coil; and a power switch contact adhesion detection device, the power switch contact adhesion detection device including: one or more power switch contact adhesion detection circuits as described in any of the above embodiments, respectively used to detect contact adhesion of any power switching unit.

[0016] As described above, this utility model has the following beneficial effects: This utility model provides a power switch sticking detection circuit, which detects the first level signal output by the contact voltage detection unit and the second level signal output by the charging current detection unit, and outputs a corresponding fault status indication signal to indicate different types of contact sticking faults, including complete contact sticking faults and loose contact sticking faults, thereby forming a multi-parameter linkage fault detection mechanism, which can effectively improve the accuracy and reliability of contact sticking detection; This utility model also provides an AC charging pile charging system, which uses one or more power switch sticking detection circuits to detect contact sticking of one or more power switch units in the AC charging pile charging circuit, thereby ensuring the charging safety of the AC charging pile charging circuit. Attached Figure Description

[0017] Figure 1 The diagram shown is a structural schematic of a power switch contact adhesion detection circuit in one embodiment of this utility model.

[0018] Figure 2 The diagram shown is a schematic diagram of the enable control circuit in one embodiment of this utility model.

[0019] Figure 3 The diagram shown is a schematic diagram of the contact voltage detection circuit in one embodiment of this utility model.

[0020] Figure 4 The diagram shown is a schematic diagram of the charging current detection circuit in one embodiment of this utility model.

[0021] Figure 5 The diagram shown is a structural schematic of an electromagnetic coil drive signal detection circuit in one embodiment of this utility model.

[0022] Figure 6 The diagram shown is a structural schematic of the first power switch specification detection circuit in one embodiment of this utility model.

[0023] Figure 7 The diagram shown is a structural schematic of the second power switch specification detection circuit in one embodiment of this utility model.

[0024] Figure 8 The diagram shown is a structural schematic of an AC charging pile charging system according to an embodiment of this utility model. Detailed Implementation

[0025] The following specific embodiments illustrate the implementation of this utility model. Those skilled in the art can easily understand other advantages and effects of this utility model from the content disclosed in this specification.

[0026] It should be understood that the structures, proportions, sizes, etc., illustrated in the accompanying drawings are merely for illustrative purposes to aid those skilled in the art and are not intended to limit the implementation of this utility model. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to size, without affecting the effectiveness and purpose of this utility model, should still fall within the scope of the technical content disclosed in this utility model. The following detailed description should not be considered restrictive, and the scope of the embodiments of this utility model is defined only by the claims of the published patents. The terminology used herein is for describing specific embodiments only and is not intended to limit the utility model. Spatial terms such as "upper," "lower," "left," "right," "below," "below," "lower part," "above," "upper part," etc., may be used in the text to illustrate the relationship between one element or feature shown in the figures and another element or feature.

[0027] In this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," "fixing," and "holding" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0028] Furthermore, as used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context indicates otherwise. It should be further understood that the terms “comprising,” “including,” indicate the presence of the stated feature, operation, element, component, item, kind, and / or group, but do not preclude the presence, occurrence, or addition of one or more other features, operations, elements, components, items, kinds, and / or groups. The terms “or” and “and / or” as used herein are interpreted as inclusive, or mean any one or any combination thereof. Thus, “A, B, or C” or “A, B, and / or C” means “any one of: A; B; C; A and B; A and C; B and C; A, B, and C.” Exceptions to this definition arise only when combinations of elements, functions, or operations are inherently mutually exclusive in some manner.

[0029] To address the problems mentioned above, this utility model provides a power switch contact adhesion detection circuit and an AC charging pile charging system, aiming to solve the technical problems of poor detection accuracy, poor reliability, and lack of contact adhesion fault detection in existing relay / contactor contact adhesion detection circuits.

[0030] To make the objectives, technical solutions, and advantages of this utility model clearer, the technical solutions in the embodiments of this utility model are further described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only for explaining this utility model and are not intended to limit this utility model.

[0031] An AC charging station transmits AC power from the power grid to the electric vehicle being charged via its charging circuit. The AC charging station includes one or more power switching units, each relying on power switches such as relays or contactors to physically control the circuit's on / off state.

[0032] like Figure 1 As shown, this utility model provides a power switch contact adhesion detection circuit for detecting contact adhesion in any power switch unit.

[0033] like Figure 1 As shown, the power switch unit includes a power switch and a driving circuit for the power switch. The power switch includes a moving contact, a stationary contact, and an electromagnetic coil. The output terminal of the driving circuit is electrically connected to the electromagnetic coil to provide the required driving voltage to the electromagnetic coil, thereby controlling the on / off state of the electromagnetic coil current. When the electromagnetic coil is energized, it generates a magnetic field, causing the moving contact to displace and contact the normally closed stationary contact, thus turning on the power switch circuit and controlling the AC charging pile charging circuit to turn on. When the electromagnetic coil is de-energized, the magnetic field disappears, and the moving contact, under the action of a return spring, disconnects from the normally closed stationary contact or contacts the normally open stationary contact, turning off the power switch circuit and controlling the AC charging pile charging circuit to turn off.

[0034] The power switch contact adhesion detection circuit includes: a contact voltage detection unit, a charging current detection unit, and a main control unit. The contact voltage detection unit includes: an enable control circuit and a contact voltage detection circuit; the charging current detection unit includes: a charging current detection circuit.

[0035] like Figure 1 As shown, the contact voltage detection circuit is electrically connected to both the moving contact and the stationary contact via the enable control circuit. The enable control circuit is also electrically connected to the main control unit to control the on / off state of the contact voltage detection circuit.

[0036] In one embodiment, such as Figure 2As shown, the enable control circuit includes a silicon controlled rectifier (SCR) chip. The first pin of the SCR chip is electrically connected to the main control unit, and the second and third pins are electrically connected to the moving contact and the contact voltage detection circuit, respectively. The SCR chip is configured to: upon receiving a start detection control signal from the main control unit at its first pin, close the second and third pins to output a high-level enable signal, thereby controlling the contact voltage detection circuit to conduct; and upon receiving an end detection control signal from the main control unit at its first pin, open the second and third pins to output a low-level enable signal, thereby controlling the contact voltage detection circuit to disconnect.

[0037] Specifically, such as Figure 2 As shown, the enable control circuit includes a silicon controlled rectifier (SCR) chip U23. Pin 1 of the SCR chip U23 is electrically connected to a 3.3-volt power supply via resistor R201, and is also electrically connected to a capacitor C168 and grounded. Pin 2 of the SCR chip U23 is electrically connected to the collector of transistor Q14. The emitter of transistor Q14 is grounded, and its base is electrically connected to the main control unit via resistor R202. Furthermore, a resistor R203 is connected in parallel between the base and emitter of transistor Q14. Pin 2 of the SCR chip U23 serves as a first pin, used to receive start and end detection control signals from the main control unit; pin 6 of the SCR chip U23 serves as a second pin, electrically connected to the moving contact of the power switch; and pin 4 serves as a third pin, electrically connected to the contact voltage detection circuit.

[0038] In this embodiment, the main control unit is electrically connected to the enable control circuit and is configured to output a control signal to the enable control circuit. This control signal includes a start detection control signal and an end detection control signal. Specifically, in response to the charging demand of the electric vehicle to be charged, the main control unit outputs a start detection control signal to the enable control circuit before charging the electric vehicle, turning on the contact voltage detection circuit to perform a pre-charging self-test of the AC charging pile charging circuit, ensuring a safe and reliable charging process. After the electric vehicle to be charged has finished charging, the main control unit outputs a start detection control signal to the enable control circuit, turning on the contact voltage detection circuit to perform a post-charging self-test of the AC charging pile charging circuit, preventing the charging interface from being continuously energized and reducing contact risks. During the charging process of the electric vehicle to be charged, the main control unit outputs an end detection control signal to the enable control circuit, turning off the contact voltage detection circuit to achieve open-circuit standby during charging, reducing the overall standby power consumption of the power switch contact adhesion detection circuit and improving the service life of each component in the circuit.

[0039] It should be noted that the main control unit is also electrically connected to the drive circuit and is configured to output control signals to the drive circuit. These control signals include a start charging control signal and a stop charging control signal. Specifically, after completing a pre-charging self-test of the AC charging pile charging circuit, the main control unit outputs a start charging control signal to the drive circuit, causing the drive circuit to conduct, thereby controlling the power switch to conduct, and controlling the AC charging pile charging circuit to conduct, thus starting the charging of the electric vehicle to be charged. After the electric vehicle to be charged has completed charging and the self-test of the AC charging pile charging circuit has been completed, the main control unit outputs a stop charging control signal to the drive circuit, causing the drive circuit to disconnect, thereby controlling the power switch to disconnect, and controlling the AC charging pile charging circuit to disconnect.

[0040] In one specific embodiment, the main control unit outputting control signals to the enable control circuit and the drive circuit can be implemented using pure hardware circuitry. Preferably, the main control unit is implemented using hardware circuitry composed of one or more AND gates and one or more OR gates.

[0041] It should be noted that this utility model protects a hardware circuit structure, that is, a hardware circuit structure that "detects the level state of the input pin and changes the level state of the output pin", and does not involve any limitation or update of software technology.

[0042] The purpose of this design in this embodiment is to use a silicon controlled rectifier chip as the enable control circuit and keep it synchronized with the control signal of the power switch in time, thereby ensuring the accuracy of contact adhesion detection and avoiding missed detection.

[0043] like Figure 1 As shown, the contact voltage detection circuit is electrically connected to the moving contact and the stationary contact respectively through the enable control circuit, and is also electrically connected to the main control unit. When the enable control circuit is turned on, it outputs a first level signal related to the voltage difference between the moving contact and the stationary contact.

[0044] In one embodiment, such as Figure 3 As shown, the contact voltage detection circuit includes a first operational amplifier. The non-inverting input of the first operational amplifier is electrically connected to the moving contact via the silicon controlled rectifier chip, the inverting input is electrically connected to the stationary contact, and the output is electrically connected to the main control unit. When the contact voltage detection circuit is turned on, it performs differential amplification on the voltage difference between the moving contact and the stationary contact and outputs the first level signal to the main control unit.

[0045] Specifically, such as Figure 3As shown, the contact voltage detection circuit includes: an operational amplifier U28 as the first operational amplifier. The non-inverting input terminal (pin 3) of the operational amplifier U28 is electrically connected to pin 6 of the thyristor chip U23 through resistors R247, R243, R241, R239, R237 and capacitor C186 in sequence; and is grounded through resistor R249; resistor R245 and capacitor C188 are also electrically connected between resistors R247 and R243, and the other end of resistor R245 and capacitor C188 is grounded. The inverting input (pin 4) of operational amplifier U28 is electrically connected to the stationary contact via resistors R248, R244, R242, R240, R238, and capacitor C187; and is electrically connected to its output (pin 1) via resistors R250 and R251. Resistor R246 and capacitor C189 are also electrically connected between resistors R248 and R244, with the other ends of resistors R246 and capacitor C189 grounded. Pin 2 of operational amplifier U28 is grounded, and pin 5 is electrically connected to a 12-volt power supply. The output of operational amplifier U28 is electrically connected to the main control unit via resistor R252 and grounded via diode D34.

[0046] In this embodiment, the present invention uses an operational amplifier to differentially amplify the voltage difference between the moving contact and the stationary contact, amplifying the voltage difference with extremely high gain, thereby effectively detecting whether the moving contact and the stationary contact are stuck together. Existing relay / contactor contact sticking detection circuits mostly use optocouplers for voltage signal amplification and transmission. However, optocouplers are easily affected by temperature, aging, etc., resulting in a significant decrease in current transfer ratio, leading to poor signal amplification accuracy and poor accuracy and reliability of contact sticking detection. The present invention uses an operational amplifier, which can effectively improve signal amplification accuracy and improve the accuracy and reliability of the power switch contact sticking detection circuit in detecting contact sticking.

[0047] It should be noted that after the contact voltage detection circuit is turned on, if the moving contact and the stationary contact do not stick together, there is no voltage difference between them, and the output first level signal is not 0; if the moving contact and the stationary contact stick together, there is a voltage difference between them, and the output first level signal is not 0; wherein, if the first level signal is an AC signal, the moving contact and the stationary contact may have a complete contact sticking fault, otherwise a contact loose sticking fault may have occurred.

[0048] like Figure 1As shown, the charging current detection circuit is electrically connected to the output terminal of the power switch and to the main control unit, and is used to output a second level signal related to the magnitude of the charging current flowing out of the power switch.

[0049] In one embodiment, such as Figure 4 As shown, the charging current detection circuit includes a current sensor. The two input terminals of the current sensor are electrically connected to the circuit at the output terminal of the power switch, and the output terminal is electrically connected to the main control unit. It is used to detect whether there is current output at the output terminal of the power switch and output the second level signal.

[0050] Specifically, such as Figure 4 As shown, the charging current detection circuit includes a current sensor T7. Pin 1 of the current sensor T7 is electrically connected to one end of the power switch output circuit via resistor R225, and pin 2 is electrically connected to the other end of the power switch output circuit via resistor R228. This is used to detect the voltage difference between the two ends of the circuit, determine the current magnitude, and thus determine whether the moving contact and the stationary contact are stuck together. Resistors R228 and R227 are connected in parallel at the first end of resistors R225 and R228, and capacitors C177 and C179 are connected in parallel at the second end. Resistors R225 and R228, and capacitors C177 and C179, are grounded. Capacitor C178 is also connected in parallel at the second end of resistors R225 and R228.

[0051] like Figure 1 As shown, the main control unit is electrically connected to the drive circuit, the enable control circuit, the contact voltage detection circuit, and the charging current detection circuit, respectively. The main control unit is configured to: output control signals to the drive circuit and the enable control circuit to turn the drive circuit and the enable control circuit on or off; receive the first level signal and the second level signal, and output a fault status indication signal when the first level signal and / or the second level signal indicates an abnormality.

[0052] It should be noted that this utility model protects a hardware circuit structure, specifically a hardware circuit structure that "detects the level state of the input pin and changes the level state of the output pin," and does not involve any limitations or updates to software technology. The fault status indication signal can be defined as different types of level signals, such as high level, low level, or pulse signal.

[0053] In one embodiment, the main control unit is configured to output a fault status indication signal in the following manner:

[0054] ① When the first level signal indicates that there is a first type of abnormal voltage difference between the moving contact and the stationary contact, and the second level signal indicates that there is a first type of abnormal current in the charging current flowing into the AC charging pile charging circuit, a first fault status indication signal is output.

[0055] Specifically, when the first level signal indicates that the voltage difference between the moving contact and the stationary contact is not zero and is an AC signal, it is determined that the moving contact and the stationary contact may have a complete contact sticking fault, and this is confirmed by the second level signal. When the second level signal indicates that the charging current is not zero and remains unchanged, it is determined that the moving contact and the stationary contact have a complete contact sticking fault, and at this time, a first fault status indication signal is output.

[0056] ② When the first level signal indicates that there is a second type of abnormal voltage difference between the moving contact and the stationary contact, and the second level signal indicates that there is a second type of abnormal current in the charging current flowing into the AC charging pile charging circuit, a second fault status indication signal is output.

[0057] Specifically, when the first level signal indicates that the voltage difference between the moving contact and the stationary contact is not zero, but is not an AC signal, it is determined that the moving contact and the stationary contact may have a contact sticking fault, and this is confirmed by the second level signal. When the second level signal indicates that the charging current is not zero, fluctuates, or is intermittent, it is determined that the moving contact and the stationary contact have a contact sticking fault, and at this time, a second fault status indication signal is output.

[0058] In one embodiment, even if the first level signal indicates that the voltage difference between the moving contact and the stationary contact is 0, it is still necessary to confirm again through the second level signal. When the second level signal indicates that the charging current is not 0, fluctuates, or is sometimes present and sometimes absent, it is determined that the moving contact and the stationary contact may still have a contact failure. At this time, a second fault status indication signal is output.

[0059] ③Otherwise, output a normal status indication signal.

[0060] It should be noted that the main control unit, used for detecting the first level signal and the second level signal, can both be implemented using purely hardware circuits, such as a combination of one or more of a comparator, oscilloscope, logic gate circuit, and dedicated level detection chip, without involving any limitations or updates to software technology. This utility model is not specifically limited.

[0061] The purpose of this design in this embodiment is to output a corresponding fault status indication signal based on the first level signal output by the contact voltage detection circuit and the second level signal output by the charging current detection circuit, so as to indicate different types of contact adhesion faults, including complete contact adhesion faults and contact loose adhesion faults, thereby forming a multi-parameter linkage fault detection mechanism to jointly realize the contact adhesion detection of the power switch unit. This not only supports the detection of contact loose adhesion faults, but also effectively improves the accuracy and reliability of contact adhesion detection.

[0062] In one embodiment, such as Figure 1 As shown, the power switch contact adhesion detection circuit further includes an electromagnetic coil drive signal detection unit. The electromagnetic coil drive signal detection unit includes an electromagnetic coil drive signal detection circuit, which is electrically connected between the output terminal of the drive circuit and the electromagnetic coil, and is also electrically connected to the main control unit. When the drive circuit is turned on, it outputs a third-level signal related to the electromagnetic coil drive voltage signal flowing into the power switch to the main control unit.

[0063] In one embodiment, such as Figure 5 As shown, the electromagnetic coil drive signal detection circuit includes a second operational amplifier and a third operational amplifier. The non-inverting input of the second operational amplifier is electrically connected between the output of the drive circuit and the electromagnetic coil, and the inverting input is electrically connected to its output. The non-inverting input of the third operational amplifier is electrically connected to the output of the second operational amplifier, the inverting input is electrically connected to its output, and it is also electrically connected to the main control unit.

[0064] Specifically, such as Figure 5As shown, the electromagnetic coil drive signal detection circuit includes: operational amplifier U27A as a second operational amplifier and operational amplifier U27B as a third operational amplifier. The non-inverting input (pin 3) of operational amplifier U27A is electrically connected between the output of the drive circuit and the electromagnetic coil via resistor R220 and diode D33. This non-inverting input is also electrically connected to capacitor C175 and resistor R223, with the other ends of capacitor C175 and resistor R223 grounded. The inverting input (pin 2) of operational amplifier U27A is electrically connected to the output (pin 1) of operational amplifier U27A, and is electrically connected to the non-inverting input (pin 5) of operational amplifier U27B via resistor R221. The non-inverting input of operational amplifier U27B is also electrically connected to resistor R224, with the other end of resistor R224 grounded. The inverting input (pin 6) of operational amplifier U27B is electrically connected to its output (pin 7), and then electrically connected to the main control unit via resistor R222. It is also electrically connected to capacitor C176 and diode D32, with the other end of capacitor C176 grounded and the other end of diode D32 electrically connected to a 3.3-volt power supply. Pin 4 of operational amplifier U27B is grounded, and pin 8 is electrically connected to a 12-volt power supply.

[0065] In this embodiment, the main control unit is further configured to output a third fault status indication signal when the third level signal indicates an abnormality in the electromagnetic coil drive voltage signal flowing into the power switch. Specifically, when the third level signal indicates an abnormality in one or more of the duty cycle, level, and frequency of the electromagnetic coil drive voltage signal, a fault is determined in the drive circuit, and the third fault status indication signal is output at this time.

[0066] Therefore, this invention can also detect faults in the drive circuit of the power switch, avoiding charging risks caused by abnormal power switches in AC charging piles.

[0067] It should be noted that the main control unit used to detect the third level signal can be implemented using pure hardware circuits, without any limitations or updates to software technology.

[0068] In one embodiment, such as Figure 1 As shown, the power switch contact adhesion detection circuit further includes a power switch specification detection unit. The power switch specification detection unit is electrically connected to the AC charging pile charging circuit and to the main control unit, and is used to output a fourth-level signal related to the standard charging current of the AC charging pile charging circuit to the main control unit.

[0069] In one embodiment, the power switch specification detection unit includes: a first power switch specification detection circuit and a second power switch specification detection circuit.

[0070] The first power switch specification detection circuit is used to acquire a positive voltage signal related to the standard charging current of the AC charging pile charging circuit, and can adopt the same circuit structure as the electromagnetic coil drive signal detection circuit. Figure 6 As shown, the first power switch specification detection circuit includes operational amplifier U25A and operational amplifier U25B. The non-inverting input (pin 3) of operational amplifier U25A is electrically connected to the input of the AC charging pile circuit via resistor R208 and diode D29. This non-inverting input is also electrically connected to capacitor C170 and resistor R211, with the other ends of capacitor C170 and resistor R211 grounded. The inverting input (pin 2) of operational amplifier U25A is electrically connected to the output (pin 1) of operational amplifier U25A, and is electrically connected to the non-inverting input (pin 5) of operational amplifier U25B via resistor R209. The non-inverting input of operational amplifier U25B is also electrically connected to resistor R212, with the other end of resistor R212 grounded. The inverting input (pin 6) of operational amplifier U25B is electrically connected to its output (pin 7), and then electrically connected to the main control unit via resistor R210. It is also electrically connected to capacitor C171 and diode D28. The other end of capacitor C171 is grounded, and the other end of diode D28 is electrically connected to a 3.3-volt power supply. Pin 4 of operational amplifier U25B is grounded, and pin 8 is electrically connected to a 12-volt power supply.

[0071] The second power switch specification detection circuit is used to acquire a negative voltage signal related to the standard charging current of the AC charging pile charging circuit, such as... Figure 7As shown, the system includes operational amplifiers U26A and U26B. The non-inverting input (pin 3) of operational amplifier U26A is electrically connected to the input of the AC charging pile circuit via resistor R214 and diode D31. This non-inverting input is also electrically connected to capacitor C173 and resistor R217, with the other ends of capacitor C173 and resistor R217 grounded. The inverting input (pin 2) of operational amplifier U26A is electrically connected to the output (pin 1) of operational amplifier U26A via resistor R219, and is electrically connected to the inverting input (pin 6) of operational amplifier U26B via resistor R215. The inverting input of operational amplifier U26B is electrically connected to its output (pin 7) via resistor R213, and to the main control unit via resistor R216. It is also electrically connected to capacitor C174 and diode D30, with the other end of capacitor C174 grounded and the other end of diode D30 electrically connected to a 3.3-volt power supply. The non-inverting input (pin 5) of operational amplifier U25B is grounded via resistor R218, pin 4 is grounded, and pin 8 is electrically connected to a 12-volt power supply.

[0072] In this embodiment, the main control unit is further configured to output a fourth fault status indication signal when the fourth level signal is inconsistent with the second level signal. The fourth level signal includes both positive and negative voltage signals. When the fourth level signal describing the standard charging current of the AC charging pile charging circuit is inconsistent with the second level signal describing the actual charging current of the AC charging pile charging circuit, it is determined that the specifications of the power switch are inconsistent, and the fourth fault status indication signal is output.

[0073] Therefore, this invention can also perform specification testing of power switches, avoiding charging risks caused by mismatched power switch specifications when charging AC charging piles.

[0074] It should be noted that the main control unit used to detect the fourth level signal can be implemented using pure hardware circuits, without any limitations or updates to software technology.

[0075] In one embodiment, such as Figure 1 As shown, the power switch contact adhesion detection circuit further includes a fault execution unit. The fault execution unit is electrically connected to the main control unit and to the AC charging pile charging circuit. Upon receiving a fault status indication signal from the main control unit, it performs an alarm operation and outputs a control signal to disconnect the AC charging pile charging circuit, ensuring charging safety.

[0076] like Figure 8 As shown, this utility model also provides an AC charging pile charging system. The AC charging pile charging system includes: an AC charging pile and a power switch contact adhesion detection device.

[0077] The AC charging pile includes an AC charging circuit. The AC charging circuit includes one or more power switching units; each power switching unit includes a power switch and a driving circuit for the power switch; the power switch includes a moving contact, a stationary contact, and an electromagnetic coil; the output terminal of the driving circuit is electrically connected to the electromagnetic coil.

[0078] The power switch contact adhesion detection device includes one or more power switch contact adhesion detection circuits, each of which is used to detect contact adhesion of any power switch unit.

[0079] It should be understood that the power switch contact adhesion detection circuit described in this application and the AC charging pile charging system belong to the same inventive concept. The power switch contact adhesion detection circuit has been described in detail in the above embodiments, and for the sake of brevity, it will not be described again here.

[0080] In summary, this utility model provides a power switch sticking detection circuit. By detecting the first level signal output by the contact voltage detection unit and the second level signal output by the charging current detection unit, it outputs corresponding fault status indication signals to indicate different types of contact sticking faults, including complete contact sticking faults and loose contact sticking faults. This forms a multi-parameter linkage fault detection mechanism, which can effectively improve the accuracy and reliability of contact sticking detection. This utility model also provides an AC charging pile charging system, which uses one or more of the above-mentioned power switch sticking detection circuits to detect contact sticking of one or more power switch units in the AC charging pile charging circuit, thereby ensuring the charging safety of the AC charging pile charging circuit. Therefore, this utility model effectively overcomes the various shortcomings of the prior art and has high industrial application value.

[0081] The above embodiments are merely illustrative of the principles and effects of this utility model and are not intended to limit the scope of this utility model. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of this utility model. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in this utility model should still be covered by the claims of this utility model.

Claims

1. A power switch contact adhesion detection circuit, used to detect contact adhesion in a power switch unit of an AC charging pile charging circuit, the power switch unit comprising: A power switch and a driving circuit for the power switch, the power switch comprising: a moving contact, a stationary contact, and an electromagnetic coil, the output terminal of the driving circuit being electrically connected to the electromagnetic coil, characterized in that it includes: A contact voltage detection unit includes an enable control circuit and a contact voltage detection circuit. The contact voltage detection circuit is electrically connected to the moving contact and the stationary contact via the enable control circuit. The enable control circuit controls the on / off state of the contact voltage detection circuit. When the enable control circuit is on, the contact voltage detection circuit outputs a first level signal related to the voltage difference between the moving contact and the stationary contact. A charging current detection unit, comprising: a charging current detection circuit; the charging current detection circuit is electrically connected to the output terminal of the power switch, and is used to output a second level signal related to the magnitude of the charging current flowing out of the power switch; The main control unit is electrically connected to the drive circuit, the enable control circuit, the contact voltage detection circuit, and the charging current detection circuit, respectively. The main control unit is configured to: output control signals to the drive circuit and the enable control circuit to turn on or off; receive the first level signal and the second level signal, and output a fault status indication signal when the first level signal and / or the second level signal indicates an abnormality.

2. The power switch contact adhesion detection circuit according to claim 1, characterized in that, The enabling control circuit includes: A silicon controlled rectifier (SCR) chip, wherein the first pin of the SCR chip is electrically connected to the main control unit, and the second and third pins are electrically connected to the moving contact and the contact voltage detection circuit, respectively, and is configured as follows: After receiving the start detection control signal from the main control unit at the first pin, the second and third pins are closed to output a high-level enable signal to control the contact voltage detection circuit to conduct. After receiving the end detection control signal from the main control unit at the first pin, the second and third pins are disconnected, thereby outputting a low-level enable signal to control the contact voltage detection circuit to disconnect.

3. The power switch contact adhesion detection circuit according to claim 2, characterized in that, The contact voltage detection circuit includes: A first operational amplifier, wherein the non-inverting input terminal of the first operational amplifier is electrically connected to the moving contact through the thyristor chip, the inverting input terminal is electrically connected to the stationary contact, and the output terminal is electrically connected to the main control unit, is used to differentially amplify the voltage difference between the moving contact and the stationary contact when the contact voltage detection circuit is turned on, and output the first level signal to the main control unit.

4. The power switch contact adhesion detection circuit according to claim 1, characterized in that, The charging current detection circuit includes: A current sensor is provided, with its two input terminals electrically connected to the circuit at the output terminal of the power switch and its output terminal electrically connected to the main control unit. The current sensor is used to detect whether there is current output at the output terminal of the power switch and to output the second level signal to the main control unit.

5. The power switch contact adhesion detection circuit according to claim 1, characterized in that, The main control unit is specifically configured as follows: When the first level signal indicates that there is a first type of abnormal voltage difference between the moving contact and the stationary contact, and the second level signal indicates that there is a first type of abnormal current in the charging current flowing into the AC charging pile charging circuit, a first fault status indication signal is output. When the first level signal indicates that there is a second type of abnormal voltage difference between the moving contact and the stationary contact, and the second level signal indicates that there is a second type of abnormal current in the charging current flowing into the AC charging pile charging circuit, a second fault status indication signal is output. Otherwise, output a normal status indication signal.

6. The power switch contact adhesion detection circuit according to claim 5, characterized in that, Also includes: An electromagnetic coil drive signal detection unit, comprising: an electromagnetic coil drive signal detection circuit; The electromagnetic coil drive signal detection circuit is electrically connected between the output terminal of the drive circuit and the electromagnetic coil, and is also electrically connected to the main control unit. When the drive circuit is turned on, it outputs a third-level signal related to the electromagnetic coil drive voltage signal flowing into the power switch to the main control unit, so that when the third-level signal indicates that there is an abnormality in the electromagnetic coil drive voltage signal flowing into the power switch, the main control unit outputs a third fault status indication signal.

7. The power switch contact adhesion detection circuit according to claim 6, characterized in that, The electromagnetic coil drive signal detection circuit includes: The second operational amplifier has its non-inverting input terminal electrically connected between the output terminal of the driving circuit and the electromagnetic coil, and its inverting input terminal electrically connected to its output terminal. The third operational amplifier has its non-inverting input electrically connected to the output of the second operational amplifier, its inverting input electrically connected to its output, and electrically connected to the main control unit.

8. The power switch contact adhesion detection circuit according to claim 5, characterized in that, Also includes: A power switch specification detection unit is electrically connected to the AC charging pile charging circuit and to the main control unit. It is used to output a fourth level signal related to the standard charging current of the AC charging pile charging circuit to the main control unit, so that the main control unit can output a fourth fault status indication signal when the fourth level signal is inconsistent with the second level signal.

9. The power switch contact adhesion detection circuit according to claim 1, characterized in that, Also includes: The fault execution unit is electrically connected to the main control unit and to the AC charging pile charging circuit. It is used to execute an alarm operation and output a control signal to disconnect the AC charging pile charging circuit upon receiving a fault status indication signal from the main control unit.

10. An AC charging pile charging system, characterized in that, include: An AC charging pile includes: an AC charging pile charging circuit; the AC charging pile charging circuit includes one or more power switching units; wherein, the power switching unit includes: a power switch and a driving circuit for the power switch; the power switch includes: a moving contact, a stationary contact, and an electromagnetic coil; the output terminal of the driving circuit is electrically connected to the electromagnetic coil. A power switch contact adhesion detection device, comprising: one or more power switch contact adhesion detection circuits as described in any one of claims 1 to 9, each used to detect contact adhesion in any power switch unit.

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