Leakage detection delay driving circuit and charging device

Abstract

This application discloses a leakage current detection delay drive circuit and charging device, relating to the field of leakage current protection technology. The leakage current detection delay drive circuit includes a leakage current detection module, a signal amplification module, a voltage divider module, a relay, a pulse widening module, and a relay drive module. The leakage current detection module outputs a leakage current induction signal when a leakage current is detected in the power supply circuit; the signal amplification module outputs a first-level signal in response to the leakage current induction signal; the pulse widening module responds to the first-level signal and outputs a second-level signal; the relay drive module responds to the second-level signal and conducts the relay coil circuit to drive the relay to disconnect. By amplifying the detected leakage current induction signal through the signal amplification module and then widening the pulse width of the amplified level signal through the pulse widening module, the relay in the power supply circuit can be directly driven to operate, giving it the function of a circuit breaker while reducing costs.

Description

Technical Field

[0001] This application relates to the field of leakage current protection technology, and in particular to a leakage current detection delay drive circuit and charging device. Background Technology

[0002] With the increasing popularity of new energy vehicles, the safety of charging facilities used for these vehicles has become a critical issue. There are significant differences in leakage protection schemes for AC and DC charging systems used in charging piles.

[0003] In DC charging systems, circuit breakers with leakage protection are typically used as leakage protection devices. While this provides some degree of leakage protection, the complex structure and high technical requirements of these circuit breakers result in high costs, hindering large-scale application. In AC charging systems, leakage protection devices rely on a control chip. When a leakage occurs, the leakage detection unit transmits the detected information to the control chip, which then cuts off the power supply to the corresponding circuit. However, this method has a low leakage protection response speed. Therefore, existing leakage detection technologies suffer from poor driving capability and high cost. Utility Model Content

[0004] The main objective of this application is to provide a leakage current detection delay drive circuit and charging device, which can improve the response speed of leakage current protection and reduce costs.

[0005] To achieve the above objectives, this application provides a leakage current detection delay driving circuit for detecting leakage current in a power supply circuit. The circuit includes a leakage current detection module, a signal amplification module, a voltage divider module, a relay, a pulse broadening module, and a relay driving module. The leakage current detection module detects leakage current in the power supply circuit and outputs a leakage current induction signal when leakage current is detected. The signal amplification module is connected to both the leakage current detection module and the voltage divider module. The signal amplification module responds to the leakage current induction signal and outputs a first-level signal. The pulse broadening module is connected to both the voltage divider module and the signal amplification module. The pulse broadening module responds to the first-level signal and outputs a second-level signal. The relay driving module is connected to both the pulse broadening module and the relay. The relay driving module responds to the second-level signal and activates the coil circuit of the relay to drive the relay to disconnect.

[0006] Optionally, the first terminal of the voltage divider module is connected to a set voltage; the signal amplification module includes a signal amplification unit connected to the output terminal of the leakage current detection module, the second terminal of the voltage divider module, and a ground terminal, used to provide the first level signal to the output terminal of the voltage divider module using the set voltage in response to the leakage current induction signal.

[0007] Optionally, the signal amplification unit includes: a first transistor, with its control electrode connected to the output terminal of the leakage current detection module, its first electrode connected to the second terminal of the voltage divider module, and its second electrode connected to the ground terminal.

[0008] Optionally, the signal amplification module includes: an anti-interference unit connected to the output terminal and ground terminal of the leakage current detection module, used to output a control signal after voltage bootstrapping using the leakage current induction signal; the signal amplification unit is used to provide the first level signal to the voltage divider terminal of the voltage divider module using the set voltage in response to the control signal.

[0009] Optionally, the anti-interference unit includes: a first capacitor, one end of which is connected to the output terminal of the leakage current detection module and the other end of which is connected to the ground terminal.

[0010] Optionally, the voltage divider terminal of the voltage divider module forms a first node; the pulse broadening module includes: a charge / discharge control unit, with a control terminal connected to the first node, a first terminal connected to a set voltage, and a second terminal connected to a third node, wherein the charge / discharge control unit is turned on in response to a first level signal to provide current to the third node using the set voltage; a charge / discharge unit, connected to the third node, a ground terminal, and a fourth node, wherein the charge / discharge unit is used to charge the third node using the current of the third node when the charge / discharge control unit is turned on, and to discharge the fourth node when the charge / discharge control unit is turned off; a voltage comparison unit. A voltage comparison unit is configured to conduct when the voltage at the fourth node is greater than or equal to a voltage threshold, thereby providing a bias voltage with a preset pulse width to the fifth node. A buffer unit is configured to conduct under the bias voltage control of the fifth node, providing a second-level signal with a preset pulse width to the second node. The preset pulse width is T, the contact closing time of the relay is t, and T / t is greater than or equal to 1.5.

[0011] Optionally, the charge / discharge control unit includes a second transistor, the control electrode of the second transistor is connected to the first node, the first electrode is connected to a set voltage, and the second electrode is connected to the third node; the charge / discharge unit includes a fifth resistor, a second capacitor, a sixth resistor, and a seventh resistor, one end of the fifth resistor is connected to the third node, the other end is connected to one end of the second capacitor, and the other end of the second capacitor is connected to ground; one end of the sixth resistor is connected to the third node, and the other end is connected to one end of the seventh resistor to form the fourth node, and the other end of the seventh resistor is connected to ground; the buffer unit includes a third transistor and a tenth resistor, the control electrode of the third transistor is connected to the fifth node through an eighth resistor, the first electrode is connected to a set voltage, and the second electrode is connected to the second node; the tenth resistor is connected between the control electrode and the first electrode of the third transistor.

[0012] Optionally, the charge / discharge control unit further includes: a third capacitor, one end of which is connected to the first node and the other end of which is connected to a set voltage; the buffer unit further includes: a fifth capacitor, which is connected between the control electrode and the first electrode of the third transistor.

[0013] Optionally, the relay drive module includes: a fourth transistor, the control electrode of which is connected to the second node through the twelfth resistor, the first electrode of which is connected to one end of the coil of the relay, and the second electrode of which is connected to the ground terminal, and the other end of the coil of the relay is connected to a set voltage; a fourth capacitor, which is connected in parallel across the twelfth resistor; and an eleventh resistor, one end of which is connected in series between the twelfth resistor and the control electrode of the fourth transistor, and the other end of which is connected to the ground terminal.

[0014] In addition, this application also provides a charging device, including the leakage current detection delay drive circuit described in any embodiment of this application.

[0015] The leakage current detection delay drive circuit provided in this application detects leakage current in the power supply circuit through a leakage current detection module and outputs a leakage current induction signal. The signal amplification module amplifies the leakage current induction signal and outputs the amplified level signal to the pulse widening module. The pulse widening module generates a level signal with a preset pulse width using a set voltage. After receiving the level signal with the preset pulse width, the relay drive module turns on the coil circuit of the relay to drive the relay to disconnect. This leakage current detection delay drive circuit does not rely on a control chip, nor does it require a circuit breaker structure with leakage current protection. It can quickly respond and accurately drive the relay to disconnect while reducing costs. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of a leakage current detection delay drive circuit according to one embodiment of this application;

[0017] Figure 2This is a schematic diagram of a leakage current detection delay drive circuit according to one embodiment of this application;

[0018] Figure 3 This is a schematic diagram of the leakage current detection delay drive circuit according to another embodiment of this application;

[0019] Figure 4 This is a schematic diagram of the leakage current detection delay drive circuit according to another embodiment of this application;

[0020] In the diagram, 100 is the leakage current detection module; 200 is the signal amplification module; 210 is the signal amplification unit; 220 is the anti-interference unit; 300 is the pulse broadening module; 310 is the charge / discharge control unit; 320 is the charge / discharge unit; 330 is the voltage comparison unit; 340 is the buffer unit; 400 is the relay drive module; 10 is the relay; and 20 is the voltage divider module.

[0021] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0023] There are significant differences in leakage current protection schemes for new energy vehicle charging facilities. DC systems rely on complex air switches, resulting in high costs, while AC systems, which process leakage signals through control chips, are susceptible to interference, leading to response delays or malfunctions. A charging station experienced leakage current protection failure due to electromagnetic interference, causing equipment damage. This exposed the deficiencies of existing solutions in terms of interference resistance and operational reliability.

[0024] Traditional leakage current protection devices have a vulnerable signal processing link. When a weak leakage current signal is detected, traditional solutions transmit it directly to the control chip for processing. However, the signal is easily affected by parasitic parameters in the circuit during transmission. Current solutions primarily improve anti-interference capabilities by constructing a hardware processing link independent of the control chip and using multi-stage signal conditioning. However, simply amplifying the signal can lead to misjudgment of short-term interference, necessitating the introduction of a delay mechanism to filter transient interference. Furthermore, it has been found that the relay drive requires sufficient power hold time to operate reliably.

[0025] Reference Figure 1This application provides a leakage current detection delay driving circuit for detecting leakage current in a power supply circuit. A relay 10 is connected in series in the power supply circuit. The leakage current detection delay driving circuit may include: a leakage current detection module 100, a signal amplification module 200, a pulse broadening module 300, and a relay driving module 400. The leakage current detection module 100 detects leakage current in the power supply circuit and outputs a leakage current induction signal when leakage is detected. The signal amplification module 200 is connected to both the leakage current detection module 100 and the voltage divider module. The signal amplification module 200 responds to the leakage current induction signal and outputs a first-level signal. The pulse broadening module 300 is connected to both the voltage divider module and the signal amplification module 200. The pulse broadening module 300 responds to the first-level signal and outputs a second-level signal. The relay driving module 400 is connected to the pulse broadening module 300 and the relay 10. The relay driving module 400 responds to the second-level signal and activates the coil circuit of the relay 10 to drive the relay 10 to disconnect.

[0026] Taking a power supply circuit consisting of L-line and N-line as an example, relay 10 can be a magnetic latching relay RLY1, which is connected in series in the power supply circuit and located before the load. The leakage current detection delay drive circuit provided in this embodiment first amplifies the detected leakage current induction signal through signal amplification module 200, and then expands the pulse width of the amplified level signal through pulse widening module 300 to meet the driving requirements of magnetic latching relay RLY1. This allows direct driving of relay 10 in the power supply circuit, enabling it to function as a circuit breaker while reducing costs.

[0027] The leakage current detection module 100 can be coupled to the power supply circuit via a current transformer. When a leakage current occurs in the power supply circuit, the leakage current detection module 100 can sense the leakage current signal and output a leakage current induction signal, which can be, for example, a leakage current signal. In this embodiment, the leakage current detection module 100 can be a leakage current detection chip.

[0028] The structure and working principle of this signal amplification module 200 will be further explained below with reference to the accompanying drawings.

[0029] Reference Figure 1 and Figure 2 The first terminal of the voltage divider module 20 is connected to the set voltage VDD, the second terminal is connected to the signal amplification module 200, and the voltage divider terminal is connected to the pulse broadening module 300. When the signal amplification module 200 is turned on, the set voltage VDD is grounded through the voltage divider module 20, thereby outputting a first-level signal to the pulse broadening module 300 through the voltage divider terminal.

[0030] The voltage divider module 20 in this embodiment can be implemented by a resistor voltage divider network. Specifically, the voltage divider module 20 may include a third resistor R3 and a fourth resistor R4. One end of the third resistor R3 and one end of the fourth resistor R4 are connected to serve as the voltage divider terminal of the voltage divider module 20. The other ends of the third resistor R3 and the fourth resistor R4 serve as the second and first ends of the voltage divider module 20, respectively.

[0031] refer to Figure 2 In this embodiment, the signal amplification module 200 may include a signal amplification unit 210, wherein the signal amplification unit 210 is connected to the output terminal of the leakage current detection module 100, the second terminal of the voltage divider module 20 and the ground terminal. The signal amplification unit 210 can be used to provide a first level signal to the output terminal of the voltage divider module 20 by using a set voltage VDD in response to the leakage current induction signal.

[0032] Specifically, the control terminal of the signal amplification unit 210 can be connected to the output terminal of the leakage current detection module 100 through a current limiting resistor R15. When the leakage current detection module 100 outputs a leakage current induction signal, the signal amplification unit 210 is turned on, thereby setting the voltage VDD to form a path to ground through the voltage divider module 20, and outputting a first level signal through the voltage divider terminal of the voltage divider module 20.

[0033] In an exemplary embodiment, such as Figure 3 As shown, the signal amplification module 200 may further include an anti-interference unit 220, which is connected to the output terminal and ground terminal of the leakage current detection module 100. This anti-interference unit 220 is used to perform voltage bootstrapping using the leakage current induction signal and then output a control signal. Based on this, the signal amplification unit 210 can be used to provide a first-level signal to the voltage divider terminal of the voltage divider module 20 using a set voltage VDD in response to the control signal.

[0034] Specifically, when the leakage current detection module 100 outputs a leakage current induction signal, the anti-interference unit 220 is charged to perform voltage bootstrapping. When the bootstrap voltage reaches a certain amplitude, a control signal is formed, and the signal amplification unit 210 is turned on under the action of the control signal. Then, the voltage VDD is set to be turned on to ground through the voltage divider module 20, and the first level signal is output through the voltage divider terminal of the voltage divider module 20.

[0035] Furthermore, due to the voltage bootstrap process, the anti-interference unit 220 can suppress the current growth rate at the control terminal of the signal amplification unit 210, causing the signal amplification unit 210 to be turned on with a delay. In this way, short-term interference signals can be eliminated, that is, short-term interference signals will not trigger the signal amplification unit 210 to turn on, thereby preventing subsequent circuits from malfunctioning and thus improving the reliability of the entire circuit.

[0036] Furthermore, in this embodiment, the signal amplification unit 210 can be implemented using a transistor, and the anti-interference unit 220 can be implemented using a capacitor. For example, continue to refer to... Figure 2 and Figure 3 The signal amplification unit 210 may include a first transistor Q1, the control electrode of the first transistor Q1 is connected to the output terminal of the leakage current detection module 100, the first electrode of the first transistor Q1 is connected to the second terminal of the voltage divider module 20, and the second electrode of the first transistor Q1 is connected to the ground terminal. The anti-interference unit 220 may include a first capacitor C1, one end of the first capacitor C1 is connected to the output terminal of the leakage current detection module 100, and the other end is connected to the ground terminal.

[0037] The leakage current detection module 100 outputs a leakage current sensing signal, which is input to the control electrode of the first transistor Q1 via the first resistor R1, causing a potential change in the first transistor Q1. As a result, the first transistor Q1 is turned on. After the first transistor Q1 is turned on, the set voltage VDD provides a voltage division value, i.e., a first level signal, through the voltage divider terminal of the voltage divider module 20 (i.e., the first node N1 in the figure), causing a potential change in the first node N1, thereby turning on the pulse broadening module 300 and triggering the subsequent circuit to perform corresponding actions.

[0038] In this embodiment, the first transistor Q1 can be a transistor, specifically an NPN transistor. This transistor can amplify the leakage current sensing signal output by the leakage current detection module 100, thereby facilitating the subsequent circuitry to perform corresponding actions.

[0039] It should be understood that, when the transistor is a bipolar junction transistor (BJT), the control electrode of the transistor in this embodiment can be the base, the first electrode can be the collector, and the second electrode can be the emitter. Alternatively, the first electrode can also be the emitter and the second electrode can be the collector. This embodiment does not impose any special limitations on this.

[0040] like Figure 3 As shown, when the leakage current detection module 100 outputs a leakage current induction signal, this signal first charges the first capacitor C1. After the first capacitor C1 is fully charged, it begins to discharge, forming the aforementioned control signal. Under the action of this control signal, the voltage divider terminal (i.e., the first node N1) of the voltage divider module 20 outputs a first-level signal. Furthermore, the first capacitor C1 can prevent the signal amplification unit 210 from being mis-energized by noise interference, thus improving the anti-interference capability of the leakage current detection delay drive circuit.

[0041] Specifically, the first capacitor C1 is charged during the rise of the control electrode voltage of the first transistor Q1, thereby suppressing the growth rate of the control electrode current and delaying the full conduction of the first transistor Q1. The process of enhancing the driving capability of the signal amplification module 200 is prolonged, and the instantaneous conduction caused by short-term interference signals is filtered out. The pulse broadening module 300 will only trigger subsequent actions when the leakage signal lasts for a sufficient time.

[0042] In summary, this embodiment, by setting a first transistor Q1, amplifies the leakage current sensing signal, thereby increasing the signal strength of the circuit. This allows the voltage divider module 20 to output a first-level signal with a certain driving capability. By setting a first capacitor C1, the signal amplification module 200 effectively suppresses transient interference signals from being falsely amplified and transmitted to subsequent circuits, thus reducing the probability of malfunction of the leakage current detection delay drive circuit. Simultaneously, it ensures that the driving capability of the actual leakage current signal is reliably enhanced and triggers protection action.

[0043] In addition, combined Figure 2 and Figure 3 In an exemplary embodiment, the signal amplification module 200 may further include a second resistor R2, which is connected between the control electrode and the second electrode of the first transistor Q1. The second resistor R2 can stabilize the control electrode voltage of the first transistor Q1.

[0044] like Figure 2 and Figure 3 As shown, in an exemplary embodiment, the relay drive module 400 may include a fourth transistor Q4, a fourth capacitor C4, an eleventh resistor R11, and a twelfth resistor R12. The control electrode of the fourth transistor Q4 is connected to the second node N2 through the twelfth resistor R12. The first electrode of the fourth transistor Q4 is connected to one end of the coil of the relay 10, and the second electrode of the fourth transistor Q4 is connected to the ground terminal. The other end of the coil of the relay 10 is connected to the set voltage VDD. The fourth capacitor C4 is connected in parallel across the two ends of the twelfth resistor R12. One end of the eleventh resistor R11 is connected in series between the twelfth resistor R12 and the control electrode of the fourth transistor Q4, and the other end is connected to the ground terminal.

[0045] Specifically, the twelfth resistor R12 is used to quickly release the charge stored in the fourth capacitor C4 when the drive signal disappears, and the eleventh resistor R11 ensures that the fourth transistor Q4 remains in the off state when there is no drive signal. Under the delay effect of the twelfth resistor R12 and the fourth capacitor C4, the fourth transistor Q4 generates a stable drive signal, which causes the coil of the relay 10 to turn off the power supply circuit.

[0046] In this embodiment, the fourth transistor Q4 can be a transistor, specifically an NPN transistor. Under the control of the level signal of the second node N2, the fourth transistor Q4 is turned on, and its conduction time is the same as the pulse width of the level signal of the second node N2, thereby providing a drive signal with a preset pulse width to the relay 10 through the fourth transistor Q4.

[0047] Furthermore, it is worth noting that the nodes described in this application can be understood as electrical connection points, that is, electrical connection points formed by the connection of multiple sub-circuits. For example, the second node N2 is an electrical connection point formed by the connection between the pulse broadening module 300 and the relay drive module 400.

[0048] The structure and working principle of the pulse widening module 300 are described in detail below.

[0049] refer to Figure 4 In an exemplary embodiment, the pulse broadening module 300 may include a charge / discharge control unit 310, a charge / discharge unit 320, a voltage comparison unit 330, and a buffer unit 340. The charge / discharge control unit 310 has its control terminal connected to a first node N1, a first terminal connected to a set voltage VDD, and a second terminal connected to a third node N3. The charge / discharge control unit 310 can be turned on in response to a level signal from the first node N1 to provide current to the third node N3 using the set voltage VDD. The charge / discharge unit 320 is connected to the third node N3, a ground terminal, and a fourth node N4. The charge / discharge unit 320 can be used to charge the third node N3 using the current from the third node N3 when the charge / discharge control unit 310 is turned on, and to discharge the fourth node N4 using the current from the fourth node N4 when the charge / discharge control unit 310 is turned off. The voltage comparison unit 330 has its reference terminal connected to the fourth node N4, its cathode connected to the fifth node N5, and its anode connected to the ground terminal. The voltage comparison unit 330 can be turned on when the voltage of the fourth node N4 is greater than or equal to a voltage threshold to provide a bias voltage with a preset pulse width to the fifth node N5. The buffer unit 340 has its control terminal connected to the fifth node N5, its first terminal connected to the set voltage VDD, and its second terminal connected to the second node N2. The buffer unit 340 can be turned on under the bias voltage control of the fifth node N5 to provide a second level signal with a preset pulse width to the second node N2.

[0050] The pulse widening module 300 processes the amplified level signal and outputs a level signal with a certain pulse width to meet the driving time requirements of the magnetic latching relay RLY1.

[0051] In detail, after the signal amplification module 200 is turned on, the first node N1 is energized, thereby changing the potential difference between the first node N1 and the set voltage VDD. This causes the charge and discharge control unit 310 to turn on. After the charge and discharge control unit 310 is turned on, the set voltage VDD charges the charge and discharge unit 320 through the third node N3. During the charging process, when the voltage of the fourth node N4 reaches the voltage threshold, the voltage comparison unit 330 is turned on, thereby providing a bias voltage with a preset pulse width to the fifth node N5. Then, through the subsequent buffer unit 340, a second level signal with a preset pulse width is provided to the second node N2.

[0052] Furthermore, when the charge / discharge control unit 310 is turned off, the charge / discharge unit 320 can discharge using the charge stored during the charging phase, thereby reducing the potential of the fourth node N4. When the potential of the fourth node N4 drops below the voltage threshold, the voltage comparison unit 330 is turned off, thereby stopping the supply of bias voltage to the fifth node N5, which in turn causes the buffer unit 340 to stop supplying the second level signal with a preset pulse width to the second node N2.

[0053] It can be seen that, with the coordinated operation of the charge and discharge control unit 310, the charge and discharge unit 320 and the voltage comparison unit 330, the pulse widening module 300 can provide a level signal with a certain pulse width to the second node N2 based on the leakage current induction signal, so that the subsequent relay drive module 400 can output a drive signal to drive the relay 10 to turn off.

[0054] In the exemplary embodiment, the preset pulse width of the level signal provided to the second node N2 is T, and the contact closing time of the relay 10 is t. Therefore, T / t is greater than or equal to 1.5, for example, it can be 1.5, 1.6, 1.8, 2.0, etc. This ensures that the level signal provided by the pulse widening module 300 to the second node N2 has a sufficient pulse width, so that the subsequent relay driving module 400 can drive the relay 10 to turn off or open. For details on the specific method of setting the preset pulse width T, please refer to the description of the following embodiments; it will not be elaborated here.

[0055] Continue to refer to Figure 4In an exemplary embodiment, the charge / discharge control unit 310 may include a second transistor Q2. The control electrode of the second transistor Q2 is connected to a first node N1, the first electrode is connected to a set voltage VDD, and the second electrode is connected to a third node N3. The charge / discharge unit 320 may include a fifth resistor R5, a second capacitor C2, a sixth resistor R6, and a seventh resistor R7. One end of the fifth resistor R5 is connected to the third node N3, and the other end is connected to one end of the second capacitor C2. The other end of the second capacitor C2 is connected to a ground terminal. One end of the sixth resistor R6 is connected to the third node N3, and the other end forms a fourth node N4 with one end of the seventh resistor R7. The other end of the seventh resistor R7 is connected to a ground terminal. The buffer unit 340 may include a third transistor Q3 and a tenth resistor R10. The control electrode of the third transistor Q3 is connected to the fifth node N5 through an eighth resistor R8, the first electrode is connected to the set voltage VDD, and the second electrode is connected to the second node N2. The tenth resistor R10 is connected between the control electrode and the first electrode of the third transistor Q3.

[0056] Specifically, the voltage comparator unit 330 can be a TL431 precision shunt regulator with a threshold voltage of 2.5V. That is, when the voltage value of the fourth node N4 exceeds 2.5V, it can provide a 2.5V voltage to the fifth node N5. The set voltage VDD can be, for example, 5V.

[0057] Both the second transistor Q2 and the third transistor Q3 can be PNP transistors. When the first transistor Q1 is turned on, the voltage division value obtained by the first node N1 is less than the set voltage VDD. As a result, the second transistor Q2 turns on to provide current to the third node N3. The current of the third node N3 charges the second capacitor C2 through the fifth resistor R5. When the voltage of the second capacitor C2 rises and the voltage value of the fourth node N4 exceeds the voltage threshold (2.5V) of the voltage comparison unit 330, the voltage comparison unit 330 turns on. The voltage of the fifth node N5 is 2.5V. Under the action of the voltage difference between the set voltage VDD (5V) and the 2.5V voltage of the fifth node N5, the third transistor Q3 turns on and provides a preset pulse width level signal to the second node N2.

[0058] When the signal amplification module 200 is turned off, the second transistor Q2 is turned off, and the second capacitor C2 stops charging and discharges through the fifth resistor R5, the sixth resistor R6 and the seventh resistor R7. During the discharge process, the voltage comparison unit 330 will only be turned off when the voltage value of the fourth node N4 is less than the voltage threshold of the voltage comparison unit 330.

[0059] In this embodiment, the second transistor Q2 and the third transistor Q3 have the same conduction level polarity, and the first transistor Q1 and the fourth transistor Q4 have the same conduction level polarity but opposite to that of the second transistor Q2. This can synchronize the signal conversion logic between the signal amplification module 200 and the pulse broadening module 300 and avoid level conversion errors.

[0060] As can be seen, by setting the second transistor Q2, the second capacitor C2, the fifth resistor R5, the sixth resistor R6, the seventh resistor R7, the voltage comparison unit 330, and the third transistor Q3, the pulse widening module 300 can output a level signal with a preset pulse width.

[0061] Continue to refer to Figure 4 In an exemplary embodiment, the charge / discharge control unit 310 may further include a third capacitor C3, one end of which is connected to the first node N1 and the other end is connected to the set voltage VDD; the buffer unit 340 may further include a fifth capacitor C5, which is connected between the control electrode and the first electrode of the third transistor Q3.

[0062] Among them, the third capacitor C3 and the fifth capacitor C5 can prevent the charging and discharging control unit 310 from being mis-connected due to external noise when receiving the level signal output by the signal amplification module 200, thus further improving the anti-interference capability of the leakage current detection delay drive circuit.

[0063] Specifically, similar to the function of the first capacitor C1, it is charged during the rise of the control electrode voltage of the second transistor Q2, thereby suppressing the growth rate of the control electrode current of the second transistor Q2, delaying the complete conduction of the second transistor Q2, and achieving a delay effect.

[0064] The fifth capacitor C5 has a similar function to the third capacitor C3, which can delay the conduction of the third transistor Q3.

[0065] In this exemplary embodiment, by setting a third capacitor C3 and a fifth capacitor C5, which work together with the first capacitor C1 to perform a three-stage delay, the anti-interference capability of the leakage detection delay drive circuit is fully guaranteed.

[0066] The above describes the specific principle of signal pulse broadening to drive relay 10 and achieve anti-interference function by the leakage current detection delay drive circuit. The following section will combine... Figures 2-4 The circuit shown details how to set the specific parameter values ​​of each component so that the leakage current detection delay drive circuit can have the above-mentioned functions.

[0067] In an exemplary embodiment, the driving time t of the magnetic latching relay RLY1 is set to be 75ms or more, and the delay time is 150ms. Taking the second capacitor C2 as an example, after the second transistor Q2 is turned on, the second capacitor C2 is charged through the fifth resistor R5. The charging time is determined by the second capacitor C2 and the fifth resistor R5. After the second transistor Q2 is turned off, the second capacitor C2 is discharged through the sixth resistor R6 and the seventh resistor R7. The resistance value of the ninth resistor R9 is greater than that of the seventh resistor R7 to avoid interference with the discharge process. In order to ensure that the second transistor Q2 is saturated and conducting, β is set to 100, design , ,but , ,Pick The sixth resistor R6 limits the current entering the voltage comparator unit 330. The saturation voltage drop of the second transistor Q2 is set to 0.3V. This means that when the third capacitor C3 is fully charged, the steady-state voltage is 4.7V, which is limited by the sixth resistor R6. ,set up ,but Actual .

[0068] Charging time of the second capacitor C2 Take 5 times To calculate the charging time, the charging time is taken as T. r =3ms, then The capacitance is set to 4.7uF. The charging time is verified to be 2.35ms, and the discharge time of the second capacitor C2 is also considered. ,in, , , , T f =150ms, C=4.7uF, substituting into the equation, we get... ,Pick The review time is T=147ms; This is the turn-on voltage of the voltage comparator unit 330. If the voltage is lower than 2.5, the subsequent stage cannot be turned on.

[0069] As can be seen, the above parameter settings enable the leakage current detection delay drive circuit to output a drive signal that drives the relay 10 to turn off or on, so that the leakage current detection delay drive circuit can directly drive the relay 10 to turn off after detecting leakage current. It should be understood that the parameter values ​​of the above devices are only illustrative examples and are not intended to limit the scope of this application.

[0070] In this embodiment, the first transistor Q1 is an NPN transistor, and the condition for the first transistor Q1 to be saturated and turned on is the on-state voltage V.BE >0.7V, and β is taken as 100, and β is taken as 100. ,but By adding a first capacitor C1 between the base and emitter, the increase in the control voltage and current of the first transistor Q1 is delayed, thereby extending the conduction time of the first transistor Q1 and achieving a delay effect. The capacitance of the first capacitor C1 is taken as 4.7uF. The time for the first capacitor C1 to charge from 0V to 0.7V is:

[0071] .

[0072] The second transistor Q2 is a PNP transistor. The condition for the second transistor Q2 to be saturated and turned on is the turn-on voltage V. BE >0.7V, and β is taken as 100, and β is taken as 100. ,but By adding a third capacitor C3 between the control electrode and the second electrode of the second transistor Q2, the increase in the voltage and current at the control electrode of the second transistor Q2 is delayed, thus achieving a time delay effect. The capacitance of the third capacitor C3 is taken as 4.7uF, and the time for the third capacitor C3 to charge from 0V to 0.7V is:

[0073] .

[0074] The third transistor Q3 is a PNP transistor. The condition for the third transistor Q3 to be saturated and turned on is the turn-on voltage V. BE >0.7V, and β is taken as 100, and β is taken as 100. ,but By adding a fifth capacitor C5 between the control electrode and the second electrode of the third transistor Q3, the increase in voltage and current at the control electrode of the third transistor Q3 is delayed, thereby achieving a time delay effect. The capacitance value of the fifth capacitor C5 is 4.7uF, and the time for the fifth capacitor C5 to charge from 0V to 0.7V is T3=T2.

[0075] Therefore, the total extension time of the leakage current detection delay drive circuit in this application is Specifically, when the capacitance values ​​of the first capacitor C1, the third capacitor C3, and the fifth capacitor C5 are all 4.7uF, the circuit can achieve a 2.1ms delay anti-interference function. This application achieves fast response and cost control in the leakage protection of charging equipment. The leakage detection delay drive circuit directly drives the relay 10 through a modular circuit, avoiding the delay caused by the control chip processing and significantly shortening the leakage protection action time; at the same time, the simplified circuit structure reduces hardware costs and is suitable for large-scale applications of AC or DC charging equipment.

[0076] Based on the above embodiments, this application also provides a charging device, which may include multiple leakage detection devices as described above.

[0077] It should be noted that details not disclosed in the charging device of this embodiment can be found in the embodiments of the leakage current detection delay drive circuit described in this specification, and will not be repeated here. It is also understood that the charging device provided in this application has the beneficial effects described in any of the above embodiments.

[0078] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Those skilled in the art can understand and implement this without any creative effort.

[0079] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. An electric leakage detection delay drive circuit characterized by comprising: The circuit is used for leakage current detection in the power supply circuit. It includes a leakage current detection module, a signal amplification module, a voltage divider module, a relay, a pulse broadening module, and a relay drive module. The leakage detection module is used to detect leakage in the power supply circuit and output a leakage induction signal when leakage is detected in the power supply circuit. The signal amplification module is connected to the leakage current detection module and the voltage divider module respectively, and the signal amplification module outputs a first level signal in response to the leakage current induction signal; The pulse broadening module is connected to the voltage divider module and the signal amplification module respectively. The pulse broadening module responds to the first level signal and outputs a second level signal. The relay driving module is connected to the pulse widening module and the relay. The relay driving module responds to the second level signal and turns on the coil circuit of the relay to drive the relay to disconnect.

2. The circuit of claim 1, wherein, The first terminal of the voltage divider module is connected to a set voltage; The signal amplification module includes: The signal amplification unit is connected to the output terminal of the leakage current detection module, the second terminal of the voltage divider module, and the ground terminal, and is used to provide the first level signal to the output terminal of the voltage divider module using the set voltage in response to the leakage current induction signal.

3. The circuit of claim 2, wherein, The signal amplification unit includes: The first transistor has its control electrode connected to the output terminal of the leakage current detection module, its first electrode connected to the second terminal of the voltage divider module, and its second electrode connected to the ground terminal.

4. The circuit of claim 2, wherein, The signal amplification module includes: An anti-interference unit is connected to the output terminal and the ground terminal of the leakage current detection module, and is used to output a control signal after voltage bootstrapping using the leakage current induction signal. The signal amplification unit is used to respond to the control signal and provide the first level signal to the voltage divider terminal of the voltage divider module using the set voltage.

5. The circuit of claim 4, wherein, The anti-interference unit includes: The first capacitor has one end connected to the output terminal of the leakage current detection module and the other end connected to the ground terminal.

6. The circuit of claim 1, wherein, The voltage divider terminal of the voltage divider module forms the first node; the pulse broadening module includes: A charge / discharge control unit has a control terminal connected to the first node, a first terminal connected to a set voltage, and a second terminal connected to a third node. The charge / discharge control unit is turned on in response to the first level signal to provide current to the third node using the set voltage. A charging and discharging unit is connected to the third node, the ground terminal, and the fourth node. The charging and discharging unit is used to charge the fourth node using the current of the third node when the charging and discharging control unit is turned on, and to discharge the fourth node when the charging and discharging control unit is turned off. A voltage comparison unit has a reference terminal connected to the fourth node, a cathode connected to the fifth node, and an anode connected to the ground terminal. The voltage comparison unit is used to turn on when the voltage at the fourth node is greater than or equal to a voltage threshold to provide a bias voltage with a preset pulse width to the fifth node. A buffer unit, with its control terminal connected to the fifth node, its first terminal connected to a set voltage, and its second terminal connected to the second node, is used to conduct under the bias voltage control of the fifth node to provide a second level signal with a preset pulse width to the second node. Wherein, the preset pulse width is T, the contact closing time of the relay is t, and T / t is greater than or equal to 1.

5.

7. The circuit of claim 6, wherein, The charge / discharge control unit includes a second transistor, the control electrode of the second transistor is connected to the first node, the first electrode is connected to a set voltage, and the second electrode is connected to the third node; The charging and discharging unit includes a fifth resistor, a second capacitor, a sixth resistor, and a seventh resistor. One end of the fifth resistor is connected to the third node, and the other end is connected to one end of the second capacitor. The other end of the second capacitor is connected to the ground terminal. One end of the sixth resistor is connected to the third node, and the other end is connected to one end of the seventh resistor to form the fourth node. The other end of the seventh resistor is connected to the ground terminal. The buffer unit includes a third transistor and a tenth resistor. The control electrode of the third transistor is connected to the fifth node through the eighth resistor, the first electrode is connected to the set voltage, and the second electrode is connected to the second node. The tenth resistor is connected between the control electrode and the first electrode of the third transistor.

8. The circuit of claim 7, wherein, The charging and discharging control unit further includes: The third capacitor has one end connected to the first node and the other end connected to a set voltage. The buffer unit further includes: The fifth capacitor is connected between the control electrode and the first electrode of the third transistor.

9. The circuit of claim 1, wherein, The relay drive module includes: The fourth transistor has its control electrode connected to the second node via the twelfth resistor, its first electrode connected to one end of the relay coil, and its second electrode connected to the ground terminal. The other end of the relay coil is connected to the set voltage. The fourth capacitor is connected in parallel across the twelfth resistor; The eleventh resistor has one end connected in series between the twelfth resistor and the control electrode of the fourth transistor, and the other end connected to the ground terminal.

10. A charging device, characterized by Includes the leakage current detection delay drive circuit as described in any one of claims 1-9.

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