Insulation detection circuit and charging pile

Abstract

The utility model discloses an insulation detection circuit and a charging pile, and belongs to the technical field of insulation detection, and the circuit comprises a sampling loop which comprises a first sampling unit, a second sampling unit and a voltage stabilization unit, and the first sampling unit and the second sampling unit are connected in series and then are connected between a first power line and a second power line; the voltage division loop is connected with the second sampling unit in parallel; the driving unit is provided with a driving input end and a driving output end, the driving input end is connected with the voltage stabilizing unit, the driving output end is connected with the voltage dividing loop, the driving unit is configured to output a driving signal, and under the condition that the driving signal controls the voltage dividing loop to be conducted, the voltage dividing loop conducts voltage dividing on the second sampling unit. The insulation detection circuit provided by the utility model is long in service life, and reduces the maintenance frequency of the charging pile.

Description

Technical Field

[0001] The embodiments of the present application relate to the field of insulation detection technology, and in particular to an insulation detection circuit and a charging pile. Background Art

[0002] With the rapid development of electric vehicles, charging stations are being used more and more frequently. These stations are typically used outdoors. Prolonged exposure to high and low temperatures accelerates aging, leading to a degradation of their insulation performance. When this insulation performance degrades to a certain level, the station generates leakage current. When a user uses the station, if this leakage current comes into contact with the human body and flows to the ground, it can pose a threat. Therefore, before using a charging station, the system must perform an insulation test on the station. However, current insulation test circuits have a short service life and require frequent replacement and maintenance. Utility Model Content

[0003] The embodiment of the present application aims to provide an insulation detection circuit and a charging pile to solve the technical problem in the prior art that the insulation detection circuit has a short service life and requires frequent replacement and maintenance.

[0004] In order to solve the above technical problems, the embodiments of the present application disclose the following technical solutions:

[0005] In a first aspect, an insulation detection circuit is provided, connected between a first power line and a second power line, comprising:

[0006] a sampling circuit, the sampling circuit comprising a first sampling unit, a second sampling unit, and a voltage stabilizing unit, wherein the first sampling unit and the second sampling unit are connected in series and then connected between the first power line and the second power line;

[0007] a voltage dividing circuit, the voltage dividing circuit being connected in parallel with the second sampling unit;

[0008] A driving unit having a driving input and a driving output, wherein the driving input is connected to the voltage stabilizing unit, and the driving output is connected to the voltage divider circuit. The driving unit is configured to output a driving signal, wherein when the driving signal is used to control the voltage divider circuit to be turned on, the voltage divider circuit divides the voltage of the second sampling unit.

[0009] In combination with the first aspect, the voltage stabilizing unit includes a first diode and a second diode, the cathode of the first diode is connected between the first sampling unit and the second sampling unit, the anode of the first diode is connected to the cathode of the second diode, and the anode of the second diode is connected to the second power line.

[0010] In combination with the first aspect, it further includes a first voltage-dividing resistor, a second voltage-dividing resistor and a third voltage-dividing resistor, the first voltage-dividing resistor is connected between the first sampling unit and the first power line, the second voltage-dividing resistor is connected between the first sampling unit and the second sampling unit and is connected in parallel with the voltage-dividing circuit, and the third voltage-dividing resistor is connected between the first sampling unit and the first diode.

[0011] In combination with the first aspect, the first sampling unit includes a first sampling resistor, and the second sampling unit includes a second sampling resistor;

[0012] The resistance values ​​of the first voltage-dividing resistor and the second voltage-dividing resistor are both greater than the resistance values ​​of the first sampling resistor and the second sampling resistor.

[0013] In combination with the first aspect, the voltage dividing circuit includes a fourth voltage dividing resistor, a first switch unit and a second switch unit, and one end of the fourth voltage dividing resistor is connected between the first sampling unit and the second sampling unit;

[0014] The first switch unit has a first switch input terminal, a first switch output terminal, and a first switch control terminal, the first switch input terminal is connected to the other end of the fourth voltage-dividing resistor, the first switch output terminal is connected to the second power line, and the first switch control terminal is connected to the driving output terminal to receive the driving signal;

[0015] The second switch unit has a second switch input terminal, a second switch output terminal and a second switch control terminal, the second switch input terminal is connected to the other end of the fourth voltage divider resistor, the second switch output terminal is connected to the second power line, and the second switch control terminal is connected to the first switch output terminal.

[0016] In combination with the first aspect, the voltage divider circuit also includes a fifth voltage divider resistor, one end of the fifth voltage divider resistor is connected to the first switch output end, and the other end of the fifth voltage divider resistor is connected to the second power line, and the resistance of the fifth voltage divider resistor is less than the resistance of the fourth voltage divider resistor.

[0017] In combination with the first aspect, the driving unit includes a photoelectric coupler, which has a coupling side and a controlled side, the coupling side includes a coupling input end and a coupling output end, the controlled side includes a controlled input end and a controlled output end, the coupling input end is configured to receive a control signal, the coupling output end is grounded, the controlled input end is configured as the driving input end, and the controlled output end is configured as the driving output end.

[0018] In combination with the first aspect, the device further includes a control unit, the control unit having a control output terminal connected to the controlled input terminal, and the control unit outputs a control signal with a high level or a low level through the control output terminal;

[0019] Wherein, when the control signal output from the control output end is at a high level, the coupling input end and the coupling output end of the driving unit are connected; when the control signal output from the control output end is at a low level, the coupling input end and the coupling output end of the driving unit are disconnected.

[0020] In combination with the first aspect, the first power line has a first power input end and a first power output end, a first switch is connected between the first power input end and the first power output end, and the sampling loop is connected between the first power input end and the first switch;

[0021] The second power line has a second power input end and a second power output end, a second switch is connected between the second power input end and the second power output end, and the sampling circuit and the voltage divider circuit are both connected between the second power input end and the second switch.

[0022] In a second aspect, a charging pile is provided, comprising the insulation detection circuit as described in any one of the first aspects.

[0023] One of the above technical solutions has the following advantages or beneficial effects:

[0024] An embodiment of the present application provides an insulation detection circuit, which is connected between a first power line and a second power line, and includes: a sampling circuit, the sampling circuit includes a first sampling unit, a second sampling unit and a voltage stabilizing unit, the first sampling unit and the second sampling unit being connected in series and then connected between the first power line and the second power line; a voltage divider circuit, the voltage divider circuit is connected in parallel with the second sampling unit; a driving unit, the driving unit having a driving input and a driving output, the driving input being connected to the voltage stabilizing unit, the driving output being connected to the voltage divider circuit, the driving unit being configured to output a driving signal, wherein, when the driving signal is to control the voltage divider circuit to be turned on, the voltage divider circuit divides the voltage of the second sampling unit. The insulation detection circuit provided by the present application can perform real-time insulation detection on the circuit, has a high detection frequency, and has a long service life, which can be consistent with the life of the charging pile, reducing the frequency of replacement and maintenance. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The following detailed description of the specific embodiments of the present application in conjunction with the accompanying drawings will make the technical solutions and other beneficial effects of the present application apparent.

[0026] Figure 1 A schematic diagram of module connections of an insulation detection circuit provided in an embodiment of the present application;

[0027] Figure 2 This is a schematic diagram of the connection of insulation detection circuit components provided in an embodiment of the present application. DETAILED DESCRIPTION

[0028] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first" and "second" are used only for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, features defined as "first" and "second" may explicitly or implicitly include one or more of the said features. In the description of the present application, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.

[0029] With the rapid development of electric vehicles, charging stations are being used more and more frequently. These stations are typically used outdoors. Prolonged exposure to high and low temperatures accelerates aging, leading to a degradation of their insulation performance. When this insulation performance degrades to a certain level, the station generates leakage current. When a user uses the station, if this leakage current comes into contact with the human body and flows to the ground, it can pose a threat. Therefore, before using a charging station, the system must perform an insulation test on the station. However, current insulation test circuits have a short service life and require frequent replacement and maintenance.

[0030] The relevant technical personnel of this application have noticed that the mainstream insulation detection of DC charging piles usually uses the bridge method to measure the insulation performance. By setting different relay switches, changing the bridge arm impedance in the system, and confirming the impedance of the positive output line and the negative output line of the charging pile to the ground, the insulation performance of the charging pile is confirmed. Due to the process limitations of MOS tubes or transistors, there are relatively few devices that can withstand high voltage and the cost is high, so the insulation detection module usually uses relays as switches. However, relays are switched under load, and long-term switching actions will cause contact arcs on the relay contacts, leading to pitting and short circuits. In addition, the relay switching action is slow, and the contacts are prone to jitter, which leads to a low frequency of insulation detection.

[0031] The specific implementation of this application is described below through examples:

[0032] like Figure 1 As shown, an embodiment of the present application provides an insulation detection circuit, which is connected between a first power line and a second power line and is used for insulation detection between the first power line and the second power line. The insulation detection circuit includes: a sampling circuit, the sampling circuit includes a first sampling unit, a second sampling unit and a voltage stabilizing unit, the first sampling unit and the second sampling unit are connected in series and then connected between the first power line and the second power line, the voltage stabilizing unit is connected to the second power line and in parallel with the second sampling unit; a voltage divider circuit, the voltage divider circuit is connected in parallel with the second sampling unit; a driving unit, the driving unit has a driving input end and a driving output end, the driving input end is connected to the voltage stabilizing unit, and the driving output end is connected to the voltage divider circuit, the driving unit is configured to output a driving signal, and the driving signal is configured to turn on the voltage divider circuit so that the voltage divider circuit divides the second sampling unit.

[0033] Specifically, a first power line and a second power line are provided in a charging pile, wherein the first power line is the positive line DC+ for DC output in the charging pile, and the second power line is the negative line DC- for DC output in the charging pile. A sampling circuit is provided, and the voltages of the first and second sampling units relative to ground in the sampling circuit are respectively obtained. The voltages of the first and second sampling units relative to ground are compared with a threshold value to obtain a voltage change between the first and second power lines. The insulation quality within the charging pile is determined based on the degree of voltage change. In this embodiment of the present application, the voltage stabilizing unit functions to control the current passing through the voltage stabilizing unit within a certain range, thereby maintaining the voltage on the drive unit side within a safe range and preventing the drive unit from being broken down by high voltage, thereby improving the safety and stability of the insulation detection circuit. The voltage divider circuit mainly functions to receive the drive signal output by the drive unit. When the drive signal is high, the voltage divider circuit connects to the sampling circuit, thereby forming a parallel relationship with the second sampling unit. The voltage divider circuit divides the voltage of the second sampling unit to further determine the voltage change within the charging pile, thereby improving the accuracy of the charging pile insulation detection and avoiding false positives.

[0034] It can be understood that the insulation detection circuit provided in this application can perform real-time insulation detection on the circuit inside the charging pile with a high detection frequency, and the service life of the insulation detection circuit is long, which can be consistent with the life of the charging pile, reducing the frequency of replacement and maintenance.

[0035] like Figure 1 and Figure 2As shown, in the embodiment of the present application, the voltage stabilizing unit includes a first diode D1 and a second diode D2, the cathode of the first diode D1 is connected between the first sampling unit and the second sampling unit, the anode of the first diode D1 is connected to the cathode of the second diode D2, and the anode of the second diode D2 is connected to the second power line.

[0036] Specifically, the first diode D1 and the second diode D2 are both Zener diodes. By utilizing the reverse breakdown characteristics of the Zener diodes, the two can be connected in series to control the current between the first diode D1 and the second diode D2 within a certain range, and ensure that the voltage on the drive unit side is maintained within a safe range, thereby improving the safety of the circuit.

[0037] It is understood that the embodiment of the present application forms a reverse series diode structure by connecting the anode of the first diode D1 to the cathode of the second diode D2, which can help stabilize the output voltage and ensure that the output voltage remains stable within a certain range. By connecting the anode of the second diode D2 to the second power line, overvoltage or overcurrent protection can be provided. When the voltage or current exceeds a certain threshold, the second diode D2 will turn on, thereby diverting the excess voltage or current to the second power line, thereby maintaining a stable output voltage. At the same time, it also protects the drive unit from damage or overload.

[0038] like Figure 1 and Figure 2 As shown, in the embodiment of the present application, a first voltage-dividing resistor R1, a second voltage-dividing resistor R2 and a third voltage-dividing resistor R3 are further included. The first voltage-dividing resistor R1 is connected between the first sampling unit and the first power line, the second voltage-dividing resistor R2 is connected between the first sampling unit and the second sampling unit, and is connected in parallel with the voltage-dividing circuit, and the third voltage-dividing resistor R3 is connected between the first sampling unit and the first diode D1.

[0039] Specifically, when performing insulation testing on the charging pile, a high voltage of 1kV needs to be loaded between the first power line and the second power line. Therefore, in order to avoid damage to the first sampling unit and the second sampling unit due to excessive voltage, a first voltage-dividing resistor R1 is connected between the first sampling unit and the first power line to divide the voltage on the input side of the first sampling unit. A second voltage-dividing resistor R2 is connected between the second sampling unit and the first sampling unit to divide the voltage on the input side of the second sampling unit. At the same time, a third voltage-dividing resistor R3 is set between the first sampling unit and the first diode D1 to divide the voltage on the input side of the first diode D1.

[0040] It can be understood that by providing the first voltage-dividing resistor R1, the second voltage-dividing resistor R2, and the third voltage-dividing resistor R3 in the sampling loop, the voltage input to the first sampling unit, the second sampling unit, and the first diode D1 can be divided into a lower voltage, thereby protecting the first sampling unit, the second sampling unit, and the first diode D1, facilitating the sampling or measurement of the voltage between the first sampling unit and the second sampling unit, and also helping to achieve the stability and accuracy of the circuit, ensuring that the output voltage remains stable within a set range.

[0041] like Figure 1 and Figure 2 As shown, in the embodiment of the present application, the first sampling unit includes a first sampling resistor r1, and the second sampling unit includes a second sampling resistor r2; the resistance values ​​of the first voltage divider resistor R1 and the second voltage divider resistor R2 are both greater than the resistance values ​​of the first sampling resistor r1 and the second sampling resistor r2.

[0042] Specifically, under normal circumstances, the resistance of the first sampling resistor r1 and the second sampling resistor r2 is 10kΩ to 100kΩ. In order to ensure that the first voltage divider resistor R1 and the second voltage divider resistor R2 can reduce the voltage across the first sampling resistor r1 and the second sampling resistor r2 as much as possible, the resistance of the first voltage divider resistor R1 and the second voltage divider resistor R2 is set to be no less than 1MΩ.

[0043] It can be understood that by setting the resistance of the first voltage-dividing resistor R1 and the second voltage-dividing resistor R2 to be significantly greater than the resistance of the first sampling resistor r1 and the second sampling resistor r2, the accuracy of the voltage-dividing circuit can be improved. When the resistance of the voltage-dividing resistor is large, the voltage drop across the input voltage between the voltage-dividing resistor and the sampling resistor is relatively small, thereby reducing the error caused by current flowing through the resistors and improving the accuracy and stability of the voltage-dividing circuit. At the same time, the input impedance of the voltage-stabilizing unit can be increased, thereby increasing the impedance of the voltage-stabilizing unit to the input signal, reducing the load impact on the external circuit, and thus improving the performance of the entire circuit.

[0044] like Figure 1 and Figure 2As shown, in the embodiment of the present application, the voltage divider circuit includes a fourth voltage divider resistor R4, a first switch unit Q1 and a second switch unit Q2, one end of the fourth voltage divider resistor R4 is connected between the first sampling unit and the second sampling unit; the first switch unit Q1 has a first switch input end, a first switch output end and a first switch control end, the first switch input end is connected to the other end of the fourth voltage divider resistor R4, the first switch output end is connected to the second power line, and the first switch control end is connected to the drive output end to receive the drive signal; the second switch unit Q2 has a second switch input end, a second switch output end and a second switch control end, the second switch input end is connected to the other end of the fourth voltage divider resistor R4, the second switch output end is connected to the second power line, and the second switch control end is connected to the first switch output end.

[0045] Specifically, both the first switch unit Q1 and the second switch unit Q2 can be bipolar transistors. Therefore, the first switch input terminal of the first switch unit Q1 is the collector of the bipolar transistor, the first switch output terminal is the emitter of the bipolar transistor, and the first switch control terminal is the base of the bipolar transistor. Similarly, the second switch input terminal of the second switch unit Q2 is the collector of the bipolar transistor, the second switch output terminal is the emitter of the bipolar transistor, and the second switch control terminal is the base of the bipolar transistor. It is understood that when the first switch control terminal of the first switch unit Q1 receives a drive signal, the first switch input terminal and the first switch output terminal are connected, and the current passing through the first switch unit Q1 pulls up the voltage level of the first switch output terminal. When the voltage level at the first switch output terminal is higher than the turn-on voltage of the second switch unit Q2, the second switch input terminal and the second switch output terminal are connected, thereby connecting the first and second switch units Q1, Q2, in parallel, and then connecting them in series with the fourth voltage-divider resistor R4. Furthermore, the fourth voltage-divider resistor R4 is connected in parallel with the second sampling unit. It is worth noting that the first switch unit Q1 is turned on based on the drive signal from the driver unit. To prevent the drive signal from being insufficient to fully turn on the first switch unit Q1, which would cause the resistance of the fourth voltage-divider resistor R4 to be unstable after being connected in parallel with the second sampling unit. By cascading the second switch unit Q2 and the first switch unit Q1, the current flowing through the fourth voltage-divider resistor R4 can drive the second switch unit Q2 to turn on after flowing through the first switch unit Q1, thereby stabilizing the resistance of the fourth voltage-divider resistor R4 after being connected in parallel with the second sampling unit. By configuring the first and second switch units Q1, Q2 can control the connection between the fourth voltage-divider resistor R4 and the sampling circuit, thereby controlling the voltage-dividing ratio of the detection circuit. This allows for dual determination of the insulation quality of the charging pile based on the different voltage-dividing ratios of the second sampling unit, thus avoiding misjudgments.

[0046] It can be understood that by setting the first switch unit Q1 and the second switch unit Q2, the voltage dividing ratio of the circuit can be accurately controlled. Specifically, by controlling the switching state of the first switch unit Q1 through the control unit, it can be selected whether to connect the fourth voltage dividing resistor R4 to the sampling loop. By controlling the switching state of the second switch unit Q2, the stability of the resistance value of the fourth voltage dividing resistor R4 after being connected in parallel with the second sampling unit can be improved. When the first switch unit Q1 is turned on, the current in the voltage dividing loop flows through the fourth voltage dividing resistor R4 and the first switch unit Q1, and the second switch unit Q2 is turned on accordingly. The fourth voltage dividing resistor R4 realizes the voltage dividing function after being connected in parallel with the second sampling unit. When the first switch unit Q1 is disconnected, the current in the voltage dividing loop no longer flows through the fourth voltage dividing resistor R4, and the fourth voltage dividing resistor R4 no longer performs voltage division, thereby achieving precise control of the voltage dividing ratio of the voltage on the sampling loop to meet specific circuit requirements.

[0047] like Figure 1 and Figure 2 As shown, in an embodiment of the present application, the voltage-dividing circuit further includes a fifth voltage-dividing resistor R5, one end of the fifth voltage-dividing resistor R5 is connected to the first switch output end, and the other end of the fifth voltage-dividing resistor R5 is connected to the second power line, and the resistance of the fifth voltage-dividing resistor R5 is less than the resistance of the fourth voltage-dividing resistor R4.

[0048] Specifically, the fifth voltage-divider resistor R5 is a biasing voltage-divider resistor connected to the second switch control terminal of the second switch unit Q2, and is used to determine the voltage at the second switch control terminal. It will be appreciated that by appropriately selecting the resistance of the fifth voltage-divider resistor R5, the voltage of the second switch unit Q2 can be maintained within an appropriate range to ensure normal operation of the second switch unit Q2. Typically, the resistance of the fifth voltage-divider resistor R5 is between 5kΩ and 20kΩ, while the resistance of the fourth voltage-divider resistor R4 is no less than 1MΩ.

[0049] It can be understood that by setting the resistance of the fifth voltage-divider resistor R5, the magnitude of the bias current input to the second switch unit Q2 can be controlled, thereby ensuring that the second switch unit Q2 can conduct normally. Furthermore, the selection of the fifth voltage-divider resistor R5 can also suppress the impact of temperature changes on the operation of the second switch unit Q2. Because the fifth voltage-divider resistor R5 is connected to other components, changes in its resistance can partially offset changes in the parameters of other components caused by temperature changes, thereby maintaining a relatively stable operating point for the second switch unit Q2.

[0050] like Figure 1 and Figure 2As shown, in an embodiment of the present application, the driving unit includes an optocoupler U1, which has a coupling side and a controlled side. The coupling side includes a coupling input terminal and a coupling output terminal, and the controlled side includes a controlled input terminal and a controlled output terminal. The coupling input terminal is configured to receive a control signal, the coupling output terminal is grounded, the controlled input terminal is configured as a driving input terminal, and the controlled output terminal is configured as a driving output terminal.

[0051] Specifically, the optocoupler U1 is typically composed of a light-emitting diode (LED) and a photoresistor (phototransistor or photodiode). In the embodiment of the present application, the coupling side is the light-emitting diode, and the controlled side is the photoresistor. When the control unit sends a control signal, the current of the control signal flows through the coupling side, and the coupling side is turned on and emits light. When the emitted light shines on the controlled side, the resistance values ​​of the controlled input end and the controlled output end will change, thereby causing the controlled input end and the controlled output end to be turned on, and the current of the controlled input end will flow to the controlled output end. That is, the optocoupler U1 outputs a drive signal, and the first switch unit Q1 is turned on by the drive signal.

[0052] It can be understood that, through the optocoupler, the control unit's output signal can be isolated and transmitted to the base of the first switch unit Q1, thereby controlling the first switch unit Q1 to conduct. This isolated transmission method prevents the control signal from interfering with the first switch unit Q1 and other circuits, ensuring the accuracy and stability of the control signal. Furthermore, the optocoupler has good anti-interference capabilities, which can reduce the impact of external interference on signal transmission and improve the system's anti-interference performance.

[0053] like Figure 1 and Figure 2 As shown, in an embodiment of the present application, a control unit is also included, the control unit has a control output end, the control output end is connected to the controlled input end, and the control unit outputs a control signal with a high level or a low level through the control output end.

[0054] Specifically, the control unit includes a gate circuit or a processor. The gate circuit can be composed of AND gates, OR gates, or NAND gates to create a control unit capable of controlling the output high and low levels. The processor can be composed of one or more of a microcontroller, a central processing unit (CPU), an embedded processor, or a multi-core processor. A microcontroller is a single-chip microcomputer that integrates a processor core, memory, input / output interfaces, and a clock. A CPU is the main processor in a computer system, responsible for executing instructions, performing arithmetic and logical operations, and controlling data flow. An embedded processor is a processor specifically designed for embedded systems, featuring low power consumption, high performance, and real-time performance. A multi-core processor integrates multiple processing cores on a single chip, enabling simultaneous execution of multiple tasks, improving the system's parallel processing capabilities and performance. These processors can output corresponding high or low-level control signals as required by the insulation detection circuit.

[0055] It can be understood that by outputting high and low level control signals through the control unit, the control of the conduction state of the first switch unit Q1 and the second switch unit Q2 is satisfied, thereby realizing the connection of the voltage divider circuit to the sampling circuit, so that the voltage changes of the first sampling unit and the second sampling unit are measured under different voltage division conditions, and then the insulation of the charging pile is judged in combination with the voltage changes.

[0056] like Figure 1 and Figure 2 As shown, in an embodiment of the present application, the first power line has a first power input terminal and a first power output terminal, a first switch K1 is connected between the first power input terminal and the first power output terminal, and a sampling loop is connected between the first power input terminal and the first switch K1; the second power line has a second power input terminal and a second power output terminal, a second switch K2 is connected between the second power input terminal and the second power output terminal, and the sampling loop and the voltage divider loop are both connected between the second power input terminal and the second switch K2.

[0057] Specifically, as described above, the first power line is the positive line DC+ for DC output in the charging pile, and the second power line is the negative line DC- for DC output in the charging pile. The positive line DC+ and the negative line DC- are the connection channels between the charging pile and the electric vehicle, primarily used to transmit DC power to the electric vehicle's battery, enabling rapid charging. They play a key role in power transmission and charging. The first switch K1 controls the connection between the positive line DC+ and the electric vehicle. When the first switch K1 is closed, the positive line DC+ is connected to the electric vehicle; when the first switch K1 is open, the positive line DC+ is disconnected from the electric vehicle. Similarly, the second switch K2 controls the connection between the positive line DC- and the electric vehicle. When the second switch K2 is closed, the positive line DC- is connected to the electric vehicle; when the second switch K2 is open, the positive line DC- is disconnected from the electric vehicle.

[0058] It can be understood that by setting an insulation detection circuit between the positive and negative lines of the charging pile, the insulation status between the charging pile and the electric vehicle can be monitored in real time, improving the safety of the charging process, protecting equipment and personnel, and providing support for fault diagnosis and maintenance.

[0059] In summary, the insulation detection circuit provided by the embodiment of the present application, when the control signal output by the control unit U2 is at a low level, the optocoupler U1 will not output a drive signal, the current of the first switch control terminal of the first switch unit Q1 is 0, and the second switch unit Q2 is in the cut-off state, then the voltage divider circuit is not connected to the sampling circuit. The second voltage divider resistor R2 and the second sampling resistor r2 are connected in parallel with the third voltage divider resistor R3, and the resistance value of the second voltage divider resistor R2 and the third voltage divider resistor R3 is half of the first voltage divider resistor R1. If a 1000V high voltage is directly loaded between the positive line DC+ and the negative line DC-, the second voltage divider resistor R2 and the second sampling resistor r2 will withstand a voltage of 200V. The voltage across the first sampling resistor r1 is U r1 , the voltage across the second sampling resistor r2 is U r2 , according to the measurement, we can get formula (1):

[0060]

[0061] Wherein, R+ is the positive impedance between the positive line DC+ and ground PE, R- is the negative impedance between the negative polarity DC- and ground PE, (R1+r1) / / R+ represents the equivalent resistance value obtained by connecting the first voltage-dividing resistor R1 in series with the first sampling resistor r1 and then in parallel with R+, and (R2+r2) / / R3 / / R- represents the equivalent resistance value obtained by connecting the second voltage-dividing resistor R2 in series with the second sampling resistor r1 and then in parallel with the third voltage-dividing resistor R3 and R-.

[0062] When the control unit U2 outputs a high level, the photocoupler U1 is turned on, the first switch unit Q1 and the second switch unit Q2 are both in a saturated conduction state, the voltage divider circuit is connected to the sampling circuit, and the second voltage divider resistor R2 and the second sampling resistor r2 are connected in parallel with the third voltage divider resistor R3 and the fourth voltage divider resistor R4. The voltage across the first sampling resistor r1 and the second sampling resistor r2 is U r1 and U r2 The calculation formula (2) is:

[0063]

[0064] Combining formula (1) and formula (2), the positive impedance R+ and negative impedance R- of the current positive line DC+ and negative line DC- to the ground PE can be calculated. (R2+r2) / / R3 / / R4 / / R- represents the equivalent resistance value obtained by connecting the second voltage-dividing resistor R2 in series with the second sampling resistor r1 and then connecting the third voltage-dividing resistor R3, the fourth voltage-dividing resistor R4 and R- in parallel. If the charging voltage requested by the electric vehicle is U3, then when U3 / R+ is greater than 500Ω / V and U3 / R- is greater than 500Ω / V, it indicates that the insulation performance in the charging pile is good and the electric vehicle can be charged normally; when U3 / R+ is greater than 100Ω / V and less than or equal to 500Ω / V, or when U3 / R- is greater than 100Ω / V and less than or equal to 500Ω / V, it indicates that the insulation performance in the charging pile has degraded and the charging pile is in an insulation alarm state; when U3 / R+ is less than or equal to 100Ω / V, or when U3 / R- is less than or equal to 100Ω / V, it indicates that the insulation of the charging pile is very poor, there is a safety risk, and charging of the electric vehicle is prohibited.

[0065] It can be understood that the insulation detection circuit provided in the embodiment of the present application realizes real-time detection of the insulation performance inside the charging pile by setting the frequency of the control signal emitted by the control unit; the bipolar transistor is used as a switching device to control the connection between the voltage divider circuit and the sampling circuit, thereby reducing the connection delay between the voltage divider circuit and the sampling circuit, and the switching action has little effect on the life of the bipolar transistor, thereby extending the service life of the insulation detection circuit and reducing the subsequent failure maintenance of the charging pile due to the expiration of the life of the insulation detection circuit.

[0066] The present embodiment provides a charging pile, including the insulation detection circuit provided in any of the above embodiments. It is understood that the working principle and beneficial effects of the insulation detection circuit provided in the present embodiment when built into the charging pile are described in the above embodiments, and the present embodiment will not be further described here.

[0067] The above is a detailed introduction to an insulation detection circuit and a charging pile provided in the embodiments of the present application. Specific examples are used in this article to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the technical solutions and core ideas of the present application; ordinary technicians in this field should understand that they can still modify the technical solutions recorded in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. An insulation detection circuit, characterized in that: connected between the first power line and the second power line, comprising: a sampling circuit, the sampling circuit comprising a first sampling unit, a second sampling unit, and a voltage stabilizing unit, wherein the first sampling unit and the second sampling unit are connected in series and then connected between the first power line and the second power line; a voltage dividing circuit, the voltage dividing circuit being connected in parallel with the second sampling unit; A driving unit having a driving input and a driving output, wherein the driving input is connected to the voltage stabilizing unit, and the driving output is connected to the voltage divider circuit. The driving unit is configured to output a driving signal, wherein when the driving signal is used to control the voltage divider circuit to be turned on, the voltage divider circuit divides the voltage of the second sampling unit.

2. The insulation detection circuit according to claim 1, wherein: The voltage stabilizing unit includes a first diode and a second diode, wherein the cathode of the first diode is connected between the first sampling unit and the second sampling unit, the anode of the first diode is connected to the cathode of the second diode, and the anode of the second diode is connected to the second power line.

3. The insulation detection circuit according to claim 2, wherein: The circuit further includes a first voltage-dividing resistor, a second voltage-dividing resistor, and a third voltage-dividing resistor. The first voltage-dividing resistor is connected between the first sampling unit and the first power line. The second voltage-dividing resistor is connected between the first sampling unit and the second sampling unit and is connected in parallel with the voltage-dividing circuit. The third voltage-dividing resistor is connected between the first sampling unit and the first diode.

4. The insulation detection circuit according to claim 3, wherein: The first sampling unit includes a first sampling resistor, and the second sampling unit includes a second sampling resistor; The resistance values ​​of the first voltage-dividing resistor and the second voltage-dividing resistor are both greater than the resistance values ​​of the first sampling resistor and the second sampling resistor.

5. The insulation detection circuit according to claim 1, wherein: The voltage dividing circuit includes a fourth voltage dividing resistor, a first switch unit and a second switch unit, and one end of the fourth voltage dividing resistor is connected between the first sampling unit and the second sampling unit; The first switch unit has a first switch input terminal, a first switch output terminal, and a first switch control terminal, the first switch input terminal is connected to the other end of the fourth voltage-dividing resistor, the first switch output terminal is connected to the second power line, and the first switch control terminal is connected to the driving output terminal to receive the driving signal; The second switch unit has a second switch input terminal, a second switch output terminal and a second switch control terminal, the second switch input terminal is connected to the other end of the fourth voltage divider resistor, the second switch output terminal is connected to the second power line, and the second switch control terminal is connected to the first switch output terminal.

6. The insulation detection circuit according to claim 5, wherein: The voltage divider circuit also includes a fifth voltage divider resistor, one end of the fifth voltage divider resistor is connected to the first switch output end, and the other end of the fifth voltage divider resistor is connected to the second power line, and the resistance of the fifth voltage divider resistor is smaller than the resistance of the fourth voltage divider resistor.

7. The insulation detection circuit according to claim 1, wherein: The driving unit includes a photoelectric coupler, which has a coupling side and a controlled side. The coupling side includes a coupling input terminal and a coupling output terminal, and the controlled side includes a controlled input terminal and a controlled output terminal. The coupling input terminal is configured to receive a control signal, and the coupling output terminal is grounded. The controlled input terminal is configured as the driving input terminal, and the controlled output terminal is configured as the driving output terminal.

8. The insulation detection circuit according to claim 7, wherein: The control unit further comprises a control unit having a control output terminal connected to the controlled input terminal, and the control unit outputs a control signal with a high level or a low level through the control output terminal; Wherein, when the control signal output from the control output end is at a high level, the coupling input end and the coupling output end of the driving unit are connected; when the control signal output from the control output end is at a low level, the coupling input end and the coupling output end of the driving unit are disconnected.

9. The insulation detection circuit according to claim 1, wherein: The first power line has a first power input end and a first power output end, a first switch is connected between the first power input end and the first power output end, and the sampling loop is connected between the first power input end and the first switch; The second power line has a second power input end and a second power output end, a second switch is connected between the second power input end and the second power output end, and the sampling circuit and the voltage divider circuit are both connected between the second power input end and the second switch.

10. A charging pile, characterized in that: The invention comprises the insulation detection circuit according to any one of claims 1 to 9.

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