Ground wire detection circuit and device of multi-phase power grid
By connecting sampling capacitor components and filter capacitor components in parallel in a multiphase power grid and utilizing voltage change detection ground wire connection, the problem of ground wire detection in a power grid without a neutral wire is solved, achieving efficient and safe power consumption detection.
Patent Information
- Application Number
- CN202423062277.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-12
- Publication Date
- 2025-12-02
- Estimated Expiration
- 2034-12-12
AI Technical Summary
In multiphase power grids without a neutral wire, it is difficult to effectively detect whether the ground wire is properly connected, which affects the safety of electricity use.
The sampling capacitor assembly and the filter capacitor assembly are connected in parallel. The ground connection is detected by the sampling module and the voltage conversion module. The voltage change after the capacitors are connected in parallel is used to determine whether the ground connection is normal.
It enables accurate detection of ground wire connections in multi-phase power grids without neutral wires, improving power safety. The circuit is simple, low-cost, does not occupy much PCB space, and has strong resistance to external interference.
Smart Images
Figure CN223624398U_ABST
Abstract
Description
Technical Field
[0001] This disclosure relates to, but is not limited to, the field of power grid detection technology, and in particular to a ground wire detection circuit and device for a multiphase power grid. Background Technology
[0002] To meet the power supply requirements of different regions, there are various power supply methods for the power grid environment, including single-phase, two-phase, and three-phase power. The power grid typically contains a live wire, a neutral wire, and a ground wire. Checking whether the ground wire is properly connected during power supply is crucial for the safety of electricity use.
[0003] In related technologies, some multiphase power grids in certain regions do not have a neutral wire, so the voltage of the neutral wire cannot be used as a criterion for judging whether the ground wire is properly connected. This makes it difficult to detect whether the ground wire is connected in these multiphase power grids without a neutral wire, thus affecting the safety of electricity use. Utility Model Content
[0004] This disclosure provides a ground wire detection circuit and device for a multiphase power grid, which can detect the ground wire connection status in a multiphase power grid without a neutral wire, thereby improving the safety of electricity use.
[0005] In a first aspect, embodiments of this disclosure provide a ground wire detection circuit for a multiphase power grid, comprising:
[0006] The system includes a sampling capacitor assembly, a sampling module, and a voltage conversion module. The sampling module includes a signal input terminal and a signal output terminal. The signal input terminal is electrically connected to the sampling capacitor assembly, and the signal output terminal is electrically connected to the voltage conversion module, so as to sample the voltage signal on the sampling capacitor assembly and transmit it to the voltage conversion module.
[0007] A grounding terminal, which is used to connect to the ground wire in a multiphase power grid;
[0008] The multiphase power grid includes multiple live wires, each of which is electrically connected to one end of a corresponding filter capacitor assembly. The other end of each filter capacitor assembly is electrically connected to the grounding terminal. Each filter capacitor assembly includes a first filter capacitor assembly and at least one second filter capacitor assembly. The sampling capacitor assembly is connected in parallel with the first filter capacitor assembly, and the capacity of the sampling capacitor assembly connected in parallel with the first filter capacitor assembly is different from the capacity of the second filter capacitor assembly.
[0009] In some embodiments, there are multiple sampling modules, and the signal output terminal of each sampling module is electrically connected to the voltage conversion module;
[0010] The sampling module includes a first sampling module and at least one second sampling module. The signal input terminal of the first sampling module is electrically connected to the sampling capacitor component, and the signal input terminal of each second sampling module is electrically connected to the corresponding second filter capacitor component.
[0011] In some embodiments, the multiphase power grid is a two-phase power grid, the live wire includes a first live wire and a second live wire, there is one second filter capacitor component, the first live wire is electrically connected to one end of the first filter capacitor component, the other end of the first filter capacitor component is electrically connected to the ground terminal, the second live wire is electrically connected to one end of the second filter capacitor component, and the other end of the second filter capacitor component is electrically connected to the ground terminal.
[0012] In some embodiments, the sampling module includes an operational amplifier follower unit, the input terminal of which is electrically connected to the signal input terminal, and the output terminal of which is electrically connected to the signal output terminal.
[0013] In some embodiments, the sampling module further includes an isolation capacitor assembly connected in series between the signal input terminal and the input terminal of the operational amplifier follower unit.
[0014] In some embodiments, the capacitance of each of the filter capacitor components is the same.
[0015] In some embodiments, the sampling capacitor assembly and each of the filtering capacitor assemblies have the same capacity.
[0016] In some embodiments, the sampling capacitor assembly includes a sampling capacitor, which is a high-voltage capacitor.
[0017] In some embodiments, each of the filter capacitor components includes a corresponding filter capacitor, which is a high-voltage capacitor.
[0018] Secondly, embodiments of this disclosure provide a ground wire detection device for a multiphase power grid, including the ground wire detection circuit for a multiphase power grid as described in any one of the embodiments of the first aspect above.
[0019] The embodiments disclosed herein include at least the following beneficial effects:
[0020] In a multiphase power grid without a neutral wire, there are multiple live wires. Each live wire is electrically connected to one end of a corresponding filter capacitor assembly. The other end of each filter capacitor assembly is electrically connected to the grounding terminal. The filter capacitor assembly includes a first filter capacitor assembly and at least one second filter capacitor assembly. The grounding terminal is used to connect to the ground wire in the multiphase power grid. When the ground wire is normally connected to the grounding terminal, the grounding terminal will be pulled down to zero potential by the ground wire. At this time, the filter capacitors are connected in parallel, and the voltage on each filter capacitor assembly is the same. However, if the ground wire is not normally connected, the grounding terminal is not at zero potential. At this time, the voltage on each filter capacitor assembly is obtained by voltage division of the series voltages between the multiple live wires. Therefore, by connecting the sampling capacitor in parallel with the first filter capacitor assembly, the voltage on the sampling capacitor is the same as the voltage on the first filter capacitor assembly connected in parallel. Since the capacitance of the sampling capacitor assembly connected in parallel with the first filter capacitor assembly is different from that of the second filter capacitor assembly, the voltage obtained by voltage division on the first filter capacitor assembly will be different from the voltage on other second filter capacitor assemblies, and also different from the voltage obtained by voltage division in the original series connection. After the voltage signal on the first filter capacitor assembly is sampled by the sampling module and transmitted to the voltage conversion module, the connection status of the wiring can be determined based on the change in the voltage signal. This allows for the detection of the ground wire connection status in a multi-phase power grid without a neutral wire, thereby improving the safety of electricity use. Attached Figure Description
[0021] Figure 1 This is a schematic diagram showing the direction of leakage current when the ground wire connection is normal in a two-phase power grid provided in this embodiment of the disclosure;
[0022] Figure 2 This is a schematic diagram showing the direction of leakage current when the ground wire connection is abnormal in a two-phase power grid provided in this embodiment of the disclosure;
[0023] Figure 3 This is another schematic diagram showing the direction of leakage current when the ground wire connection is abnormal in a two-phase power grid provided in this embodiment of the disclosure;
[0024] Figure 4 This is a schematic diagram of a ground wire detection circuit for a two-phase power grid provided in an embodiment of this disclosure;
[0025] Figure 5 This is a schematic diagram of a ground wire detection device for a multiphase power grid provided in an embodiment of this disclosure. Detailed Implementation
[0026] In the description of this disclosure, it should be understood that the orientation descriptions, such as up, down, front, back, left, right, etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing this disclosure and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the embodiments of this disclosure.
[0027] It should be understood that in the description of the embodiments of this disclosure, "several" means one or more, "multiple" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. If "first," "second," etc., are used in the description, they are only for the purpose of distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.
[0028] In the description of the embodiments of this disclosure, unless otherwise expressly limited, terms such as setting, installing, and connecting should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in the embodiments of this disclosure in conjunction with the specific content of the technical solution.
[0029] In the description of this disclosure, references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this disclosure. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.
[0030] There are various power supply methods for different power grid environments, including single-phase, two-phase, and three-phase power, and systems with and without a neutral wire. The US power grid is particularly diverse. During charging, ensuring user safety requires real-time monitoring of the charging station's grounding system. However, detecting a missing ground wire in a system without a neutral wire presents challenges, as the neutral wire voltage cannot be used as a criterion for determining if the ground wire is disconnected.
[0031] Based on this, the present disclosure provides a ground wire detection circuit and device for a multiphase power grid, which can detect the ground wire connection status in a multiphase power grid without a neutral wire, thereby improving the safety of electricity use.
[0032] Below, we will first introduce the ground wire detection circuit of the multiphase power grid in the embodiments of this disclosure.
[0033] In some embodiments, the ground wire detection circuit for a multiphase power grid provided in this disclosure includes:
[0034] The sampling capacitor assembly, the sampling module, and the voltage conversion module are provided. The sampling module includes a signal input terminal and a signal output terminal. The signal input terminal is electrically connected to the sampling capacitor assembly, and the signal output terminal is electrically connected to the voltage conversion module, so as to sample the voltage signal on the sampling capacitor assembly and transmit it to the voltage conversion module.
[0035] The grounding terminal is used to connect to the ground wire in a multiphase power grid.
[0036] The multiphase power grid includes multiple live wires, each of which is electrically connected to one end of a corresponding filter capacitor assembly. The other end of each filter capacitor assembly is electrically connected to a grounding terminal. The filter capacitor assembly includes a first filter capacitor assembly and at least one second filter capacitor assembly. The sampling capacitor assembly is connected in parallel with the first filter capacitor assembly, and the capacity of the sampling capacitor assembly connected in parallel with the first filter capacitor assembly is different from the capacity of the second filter capacitor assembly.
[0037] In this embodiment of the disclosure, the sampling capacitor assembly may include one or more sampling capacitors. When the sampling capacitor assembly includes multiple sampling capacitors, the multiple sampling capacitors can be connected in parallel or in series to form the final sampling capacitor assembly. Similarly, the filtering capacitor assembly may include one or more filtering capacitors. When the filtering capacitor assembly includes multiple filtering capacitors, the multiple filtering capacitors can be connected in parallel or in series to form the final filtering capacitor assembly.
[0038] The sampling module comprises multiple electronic components and includes signal input and signal output terminals. The sampling circuit samples the voltage signal at the signal input terminal, processes it through the various electronic components within the module, and then outputs the sampled voltage signal through the signal output terminal. The voltage conversion module can be composed of an analog-to-digital converter (ADC), which performs digital-to-analog conversion on the voltage signal from the signal output terminal to obtain the corresponding voltage value.
[0039] In the multiphase power grid of this disclosure embodiment, there are multiple live wires. Each live wire is electrically connected to one end of a corresponding filter capacitor assembly, and the other end of each filter capacitor assembly is electrically connected to a ground terminal. Therefore, the number of filter capacitor assemblies is the same as the number of live wires. For example, if the multiphase power grid is a two-phase power grid, there are two live wires, so there are two corresponding filter capacitor assemblies. If the multiphase power grid is a three-phase power grid, there can be three or other numbers of live wires, and the corresponding filter capacitor assemblies are set accordingly. This disclosure embodiment does not impose specific limitations on this. It should be noted that the following description uses a two-phase power grid as an example of a multiphase power grid, but this does not represent a limitation on the embodiments of this disclosure.
[0040] It should be noted that the filter capacitor assembly can be divided into a first filter capacitor assembly and a second filter capacitor assembly according to the connection relationship. The sampling capacitor assembly can be connected in parallel with the first filter capacitor assembly, and the sampling capacitor assembly can be used to adjust the capacitance of the parallel capacitor assembly so that the capacitance of the sampling capacitor assembly connected in parallel with the first filter capacitor assembly is different from the capacitance of the second filter capacitor assembly.
[0041] Furthermore, the ground wire detection circuit of the multiphase power grid in this embodiment can be provided with a circuit board. The sampling capacitor assembly, sampling module, and voltage conversion module can be disposed on the circuit board, and the circuit board has a ground terminal (PE). It should be noted that the first filter capacitor assembly and the second filter capacitor assembly can be capacitor assemblies that are built into the multiphase power grid. Therefore, the ground wire detection circuit in this embodiment can be provided without a filter capacitor assembly, but connected to the filter capacitor assembly in the multiphase power grid. For example, the sampling capacitor assembly can be connected in parallel with the first filter capacitor assembly through a wire or other interface, thereby detecting the ground wire connection status in a multiphase power grid without a neutral wire. Therefore, this embodiment has the characteristics of simple circuit, easy implementation, and not occupying too much PCB space. Such a circuit has low material cost, can stably achieve real-time detection, and is not easily affected by external interference. In addition, the multiphase power grid may not contain the first filter capacitor assembly and the second filter capacitor assembly. Therefore, the first filter capacitor assembly and the second filter capacitor assembly can be disposed on the circuit board of the ground wire detection circuit, and then connected to the live wire and the ground wire in the multiphase power grid to be tested through a wire or other interface to detect the ground wire connection status.
[0042] It should be noted that the example used is a two-phase power grid in the United States, which refers to a 240VAC two-phase power grid as a multi-phase power grid. For example... Figure 1 As shown, Figure 1 This is a schematic diagram illustrating the leakage current direction when the ground wire is normally connected in a two-phase power grid according to an embodiment of this disclosure. In the diagram, L1 and L2 represent the two live wires in the two-phase power grid, capacitor C1 represents a filter capacitor in the first filter capacitor assembly, capacitor C3 represents a filter capacitor in the second filter capacitor assembly, and PE represents the grounding terminal. When the ground wire is normally connected to the grounding terminal, the grounding terminal PE will be pulled down to zero potential by the ground wire. At this time, the filter capacitors are connected in parallel, that is, capacitor C1 and capacitor C3 are connected in parallel. Capacitors have the function of blocking DC and passing AC. Therefore, in the AC mains system, capacitors C1 and C3 have a certain leakage current, and their voltages are respectively V. C1 =C3 / (C1+C3)*V L1-L2 and V C3 =C1 / (C1+C3)*V L1-L2 V C1 V is the voltage across capacitor C1. C3V is the voltage across capacitor C3. L1-L2 This refers to the voltage between live wires L1 and L2, which is the AC mains voltage of 240VAC. When capacitors C1 and C3 are equal, V... C1 =V C3 =1 / 2*V L1-L2 That is, the voltages across capacitors C1 and C3 are 120VAC respectively.
[0043] If the ground wire is not properly connected, the grounding terminal is not at zero potential. Therefore, the voltage at the PE point is not directly related to the mains ground wire. In this case, the voltage across each filter capacitor assembly is obtained by voltage division across multiple live wires in series, that is, the voltage is obtained by voltage division between capacitors C1 and C3. Therefore, the connection between the mains ground wire and the PE grounding terminal can be determined by detecting the voltage across capacitors C1 and / or C3.
[0044] When capacitors C1 and C3 have the same capacitance, the voltage across them is the same because the voltages between the ground wire and live wires L1 and L2 are identical, making them difficult to distinguish. Therefore, if... Figure 2 As shown, Figure 2 This is a schematic diagram of the leakage current direction when the ground wire connection is abnormal in a two-phase power grid provided in this embodiment of the disclosure. This embodiment of the disclosure introduces a sampling capacitor assembly. Taking a sampling capacitor assembly including a capacitor C2 as an example, by connecting capacitor C2 in parallel with capacitor C1, the capacitance of capacitor C1 after parallel connection can be changed. That is, the capacitance of capacitor C1 and capacitor C2 after parallel connection is different from that of capacitor C3. Therefore, the voltage obtained by voltage division on capacitor C1 will be different from that of capacitor C3. However, connecting capacitor C1 and C2 in parallel will not affect the filtering effect originally played by capacitor C1, nor will it affect the filtering frequency range of capacitor C1.
[0045] Subsequently, the voltage signal on the first filter capacitor assembly is sampled by the sampling module and transmitted to the voltage conversion module, that is, the voltage signal of capacitor C1 is transmitted to the voltage conversion module. The change in voltage signal can then determine whether the wiring is properly connected. For example, when the ground wire connection is normal, the voltages on capacitors C1 and C3 are 120VAC respectively. However, when the ground wire connection is abnormal, if capacitor C2 is connected in parallel across capacitor C1, the capacitance of the parallel connection of C1 and C2 is (C1*C2) / (C1+C2). If capacitor C1 equals capacitor C2, the capacitance of the parallel connection of C1 and C2 is 1 / 2*C1, and the voltage of capacitor C1 becomes V. C1 =V C2 =C3 / (1 / 2*C1+C3)*V L1-L2 V C2 The voltage across capacitor C2 is V, and the voltage across capacitor C3 becomes V. C3= (1 / 2*C1) / (1 / 2*C1+C3)*V L1-L2 .
[0046] If capacitor C1 = capacitor C2 = capacitor C3, then V C1 =V C2 =2 / 3*V L1-L2 V C3 =1 / 2*
[0047] C1 / (1 / 2*C1+C3)*V L1-L2 =1 / 3*V L1-L2 When V L1-L2 When the voltage is 240VAC, the voltage on capacitor C1 is 120VAC when the ground wire is in good contact. However, when the ground wire is in abnormal contact, the voltage on capacitor C1 will become 160VAC. Therefore, the voltage on capacitor C1 has changed. In this embodiment, the ground wire connection can be determined based on the magnitude or change of the voltage on capacitor C1.
[0048] Furthermore, such as Figure 3 As shown, Figure 3 This is another schematic diagram of the leakage current direction when the ground wire connection is abnormal in a two-phase power grid provided in this embodiment. Capacitor C3 can also be used as the first filter capacitor component, and capacitor C2 and capacitor C3 are connected in parallel to detect the voltage on capacitor C3. This embodiment does not impose specific limitations on this.
[0049] In summary, the embodiments of this disclosure can detect the ground wire connection status in a multi-phase power grid without a neutral wire, improving power safety. Furthermore, the size of the filter capacitor assembly is closely related to the filtering noise range and effect of the mains power; therefore, the size of a single filter capacitor assembly cannot be modified. However, in the embodiments of this disclosure, the sampling capacitor assembly is connected in parallel with the first filter capacitor assembly, thus not affecting the filtering effect of the original first filter capacitor assembly or its filtering frequency range.
[0050] It should be noted that the term "electrical connection" in this disclosure embodiment is also called "electrical link," which is a connection relationship used to illustrate this characteristic of the circuit when describing the circuit structure of a product. It can be understood as a form of connection between different components in the circuit structure through physical lines that can transmit electrical signals, such as PCB copper foil or wires. It is understood that the two electronic components in an "electrical connection" can be directly connected, or they can be indirectly connected by other electronic components in between.
[0051] Furthermore, in some embodiments, there are multiple sampling modules, and the signal output terminal of each sampling module is electrically connected to the voltage conversion module;
[0052] The sampling module includes a first sampling module and at least one second sampling module. The signal input terminal of the first sampling module is electrically connected to the sampling capacitor component, and the signal input terminal of each second sampling module is electrically connected to the corresponding second filter capacitor component.
[0053] In this embodiment, the number of sampling modules is consistent with the number of filter capacitor components to be sampled. The sampling modules can be divided into a first sampling module and a second sampling module based on the object being sampled. The first sampling module corresponds to a sampling capacitor component, and its signal input terminal is electrically connected to the sampling capacitor component. It samples the voltage signal on the sampling capacitor component and transmits it to the voltage conversion module. The second sampling module samples other filter capacitor components. Therefore, the signal input terminal of each second sampling module is electrically connected to the corresponding second filter capacitor component, thereby sampling the voltage signal on the second filter capacitor component and transmitting it to the voltage conversion module.
[0054] It should be noted that, by setting up multiple sampling modules, the voltage of different filter capacitor components can be sampled separately. After sampling, the voltage signal of the corresponding filter capacitor component is transmitted to the voltage conversion module. The voltage conversion module compares the voltage magnitudes on different filter capacitor components, and thus determines whether the ground wire is properly connected based on the voltage differences. This allows for a more accurate understanding of the voltage changes on each filter capacitor component, thereby better determining the ground wire connection status. For example, with... Figure 2 In the example, if the voltage across capacitor C1 and capacitor C3 is both 120VAC, the ground connection can be considered normal. However, since capacitor C2 is connected in parallel with capacitor C1, if the voltage across capacitor C1 is 160VAC and the voltage across capacitor C3 is 80VAC, the ground connection can be considered abnormal.
[0055] It should be noted that when only one sampling module is provided in this embodiment of the present disclosure, that is, when only one sampling module is connected to the sampling capacitor component, the voltage on the sampling capacitor component, that is, the voltage on the first filter capacitor component, can be measured by the voltage conversion module, and the grounding connection can be determined based on whether the voltage changes. For example, with Figure 2 In the example, if the voltage of capacitor C1 is detected to change from 120VAC to 160VAC, it can be considered that the ground connection is abnormal.
[0056] Furthermore, the multiphase power grid is a two-phase power grid, the live wires include a first live wire and a second live wire, there is one second filter capacitor assembly, the first live wire is electrically connected to one end of the first filter capacitor assembly, the other end of the first filter capacitor assembly is electrically connected to the ground terminal, the second live wire is electrically connected to one end of the second filter capacitor assembly, and the other end of the second filter capacitor assembly is electrically connected to the ground terminal.
[0057] In this embodiment, the multiphase power grid is a two-phase power grid, such as the two-phase power grid in the United States. Therefore, the two-phase power grid includes two live wires, namely a first live wire and a second live wire, and also includes a ground wire. Since the number of filter capacitor components is the same as the number of live wires, there is one first filter capacitor and one second filter capacitor component. The first live wire is electrically connected to one end of the first filter capacitor component, and the other end of the first filter capacitor component is electrically connected to the ground terminal. The second live wire is electrically connected to one end of the second filter capacitor component, and the other end of the second filter capacitor component is electrically connected to the ground terminal. This embodiment, when applied to a two-phase power grid, solves the problem of the difficulty in ground wire detection in a two-phase power grid without a neutral wire.
[0058] Furthermore, the sampling module includes an operational amplifier follower unit, the input terminal of which is electrically connected to the signal input terminal, and the output terminal of which is electrically connected to the signal output terminal.
[0059] In this embodiment, the op-amp follower unit, also known as a voltage follower or buffer, is a circuit composed of an operational amplifier (Op-Amp). Its main function is to provide high input impedance and low output impedance, meaning it draws almost no current from its input (high input impedance) and can easily drive any load connected to its output (low output impedance). Specifically, the input of the op-amp follower unit is electrically connected to the signal input terminal, and the output of the op-amp follower unit is electrically connected to the signal output terminal. That is, by inserting an op-amp follower unit, the voltage signal at the signal input terminal can be followed / amplified by the op-amp follower unit and output, and finally output to the voltage conversion module for ADC conversion through the signal output terminal.
[0060] Furthermore, the sampling module also includes an isolation capacitor assembly connected in series between the signal input terminal and the input terminal of the operational amplifier follower unit.
[0061] In this embodiment, when the grounding detection circuit of a multiphase power grid is applied in a high-voltage environment, insulation testing needs to be performed under DC high voltage, such as DC 500V. Since mains power is AC, this increases the insulation impedance under DC conditions and also reduces interference from the DC component in the high-impedance state. Therefore, by setting an isolation capacitor assembly connected in series between the signal input terminal and the input terminal of the operational amplifier follower unit, the DC high voltage is applied across the isolation capacitor assembly during insulation impedance testing, and not to other electronic components of the sampling module, such as resistors. This also reduces the risk of arcing on resistors, which could lead to resistor breakdown and damage.
[0062] Furthermore, the isolation capacitor assembly may include one or more isolation capacitors. When the isolation capacitor assembly includes multiple isolation capacitors, these capacitors can be connected in parallel or series to form the final isolation capacitor assembly. The isolation capacitor assembly uses high-voltage capacitors, which can effectively reduce DC component interference under high impedance conditions. Additionally, if the isolation capacitor assembly is not a high-voltage capacitor, or if no isolation capacitor assembly is included in the sampling module, then a large-package resistor needs to be used in the sampling module to avoid the risk of resistor breakdown. This disclosure does not impose specific limitations on this aspect.
[0063] For example, consider a scenario where both the first sampling module and the second sampling module are equipped with isolation capacitor components. Figure 4 As shown, Figure 4 This is a schematic diagram of a ground wire detection circuit for a two-phase power grid provided in an embodiment of this disclosure. The diagram illustrates, for example, a first filter capacitor assembly including a capacitor C1 as a filter capacitor; a second filter capacitor assembly including a capacitor C3 as a filter capacitor; a sampling capacitor assembly including a capacitor C2 as a sampling capacitor; an isolation capacitor assembly in the first sampling module including a capacitor C6 as an isolation capacitor; an operational amplifier follower unit in the first sampling module including an operational amplifier follower VF1 as an example; an isolation capacitor assembly in the second sampling module including a capacitor C7 as an isolation capacitor; and an operational amplifier follower unit in the second sampling module including an operational amplifier follower VF2 as an example.
[0064] Furthermore, in the first sampling module, capacitor C2 is connected in parallel with capacitor C1. The live wire L1 is connected to one end of capacitors C1 and C2. Capacitor C6 is also connected to one end of capacitors C1 and C2. The connection point between capacitor C6 and one end of capacitors C1 and C2 serves as the signal input terminal of the first sampling module. The other ends of capacitors C1 and C2 are connected to the ground terminal PE. Resistors R1, R2, and R3 are connected in series between the non-inverting input terminal of the op-amp follower VF1 and capacitor C6. Resistors R1, R2, and R3 are also connected in parallel with resistor R4 and then connected to the op-amp follower. In the non-inverting input terminal of the operational amplifier follower VF1, a resistor R5 is connected to the inverting input terminal of the operational amplifier follower VF1, and a resistor R6 is connected to the output terminal of the operational amplifier follower VF1. A resistor R7 is also connected in series between the output terminal of the operational amplifier follower VF1 and the signal output terminal ADC_L1 of the first sampling module. An additional filter capacitor C4 is provided. One end of the capacitor C4 is connected between the resistor R7 and the signal output terminal ADC_L1, and the other end of the capacitor C4 is connected to the ground terminal PE. The magnitude of the input and output signals can be adjusted by using multiple resistors. This embodiment of the present disclosure does not impose specific limitations on this.
[0065] Similarly, in the second sampling module, the live wire L2 is connected to one end of capacitor C3, and capacitor C7 is also connected to one end of capacitor C3. The connection point between capacitor C7 and one end of capacitor C3 is the signal input terminal of the second sampling module. The other end of capacitor C3 is connected to the ground terminal PE. Resistors R8, R9, and R10 are connected in series between the non-inverting input terminal of op-amp follower VF2 and capacitor C7. Resistors R8, R9, and R10 are also connected in parallel with resistor R11 and then connected to the non-inverting input terminal of op-amp follower VF8. The inverting input terminal of VF2 is connected to a resistor R12, and is connected to the output terminal of the op-amp follower VF2 through a resistor R13. The output terminal of the op-amp follower VF2 is also connected in series with a resistor R14 between it and the signal output terminal ADC_L2 of the second sampling module. An additional filter capacitor C5 is provided. One end of the capacitor C5 is connected between the resistor R14 and the signal output terminal ADC_L2, and the other end of the capacitor C5 is connected to the ground terminal PE. The magnitude of the input and output signals can be adjusted by using multiple resistors. This embodiment of the present disclosure does not impose specific limitations on this.
[0066] Furthermore, the capacitance of each filter capacitor component is the same.
[0067] In this embodiment, the capacitance of the first filter capacitor assembly is the same as that of each of the second filter capacitor assemblies, to facilitate rapid calculation of the voltage sampled by each sampling module when the ground connection is normal or abnormal. For example, in Figure 4 In the example, capacitor C1 has the same capacitance as capacitor C3. This makes it easier to calculate the voltage drop across capacitors C1 and C3 when the ground wire is not connected, thus better determining the ground wire connection status.
[0068] Furthermore, the sampling capacitor assembly has the same capacitance as each of the filter capacitor assemblies.
[0069] In this embodiment, the capacitance of the sampling capacitor assembly is the same as that of each filter capacitor assembly, to further facilitate rapid calculation of the voltage magnitude sampled by each sampling module when the ground connection is normal or abnormal. For example, in Figure 4 In the example, the capacitances of capacitors C1, C2, and C3 are the same. Therefore, when the ground connection is normal, the voltage across capacitor C1 and capacitor C3 is 120VAC. However, when the ground connection is abnormal, the voltage across capacitor C1 is 160VAC and the voltage across capacitor C3 is 80VAC. This helps to more easily calculate the voltages divided by capacitors C1 and C3 when the ground connection is not connected, thus better determining the ground connection status.
[0070] Furthermore, the sampling capacitor assembly includes a sampling capacitor, which is a high-voltage capacitor.
[0071] In this embodiment, the sampling capacitor in the sampling capacitor assembly is a high-voltage capacitor. Further, the sampling capacitor is a Y-capacitor. Using the Y-capacitor as the sampling capacitor and connecting it in parallel with the first filter capacitor assembly will not affect the filtering frequency range of the first filter capacitor assembly. For example, in... Figure 4 In the example, capacitor C2 is a Y capacitor.
[0072] Furthermore, each filter capacitor assembly includes a corresponding filter capacitor, which is a high-voltage capacitor.
[0073] In this embodiment, each filter capacitor is a high-voltage capacitor. Furthermore, the filter capacitor is a Y-type capacitor. Using a Y-type capacitor as a filter capacitor can provide a better filtering effect in a high-voltage power grid, preventing the normal operation of the circuit from being affected by high-voltage breakdown. For example, in... Figure 4 In the example, capacitors C1 and C3 are both Y capacitors.
[0074] The following describes a ground wire detection device for a multiphase power grid provided in an embodiment of this disclosure.
[0075] like Figure 5 As shown, Figure 5 This is a schematic diagram of a ground wire detection device for a multiphase power grid provided in an embodiment of this disclosure. This disclosure provides a ground wire detection device for a multiphase power grid, including the ground wire detection circuit for the multiphase power grid described in any of the foregoing embodiments.
[0076] In some embodiments, the ground wire detection device for a multiphase power grid includes multiple live wires in a multiphase power grid without a neutral wire. Each live wire is electrically connected to one end of a corresponding filter capacitor assembly, and the other end of each filter capacitor assembly is electrically connected to a grounding terminal. The filter capacitor assembly includes a first filter capacitor assembly and at least one second filter capacitor assembly. The grounding terminal is used to connect to the ground wire in the multiphase power grid. When the ground wire is normally connected to the grounding terminal, the grounding terminal is pulled down to zero potential by the ground wire. At this time, the filter capacitors are connected in parallel, and the voltage on each filter capacitor assembly is the same. However, if the ground wire is not normally connected, the grounding terminal is not at zero potential. At this time, the voltage on each filter capacitor assembly is obtained by voltage division of the series voltages between the multiple live wires. Therefore, by connecting the sampling capacitor in parallel with the first filter capacitor assembly, the voltage on the sampling capacitor is the same as the voltage on the first filter capacitor assembly connected in parallel. Since the capacitance of the sampling capacitor assembly connected in parallel with the first filter capacitor assembly is different from that of the second filter capacitor assembly, the voltage obtained by voltage division on the first filter capacitor assembly will be different from the voltage on other second filter capacitor assemblies, and also different from the voltage obtained by voltage division in the original series connection. After the voltage signal on the first filter capacitor assembly is sampled by the sampling module and transmitted to the voltage conversion module, the connection status of the wiring can be determined based on the change in the voltage signal. This allows for the detection of the ground wire connection status in a multi-phase power grid without a neutral wire, thereby improving the safety of electricity use.
[0077] For example, the ground wire detection device for a multiphase power grid can be any detection device or electrical appliance. This detection device can also be applied to electrical appliances, and these appliances can be any devices that need to be connected to the mains power, such as car charging stations or household appliances. In this embodiment, only a car charging station is used as an example of a multiphase power grid ground wire detection device, or its application in a car charging station, is used for illustration. By setting up a ground wire detection circuit for the multiphase power grid, the charging station can detect the connection status of the ground wire in a multiphase power grid without a neutral wire, thereby improving the safety of electricity use.
[0078] The specific implementation of the ground wire detection device for this multiphase power grid is basically the same as the specific embodiment of the ground wire detection circuit for the multiphase power grid described above, and will not be repeated here. Subject to meeting the requirements of the embodiments of this disclosure, the ground wire detection device for the multiphase power grid may also be equipped with other functional modules or circuits to achieve the functions of the ground wire detection circuit for the multiphase power grid described above.
[0079] It should also be understood that the various implementation methods provided in this disclosure can be combined arbitrarily to achieve different technical effects.
[0080] The above is a detailed description of the preferred embodiments of this disclosure. However, this disclosure is not limited to the above embodiments. Those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of this disclosure. All such equivalent modifications or substitutions are included within the scope defined by the claims of this disclosure.
Claims
1. A ground wire detection circuit for a multiphase power grid, characterized in that, include: The system includes a sampling capacitor assembly, a sampling module, and a voltage conversion module. The sampling module includes a signal input terminal and a signal output terminal. The signal input terminal is electrically connected to the sampling capacitor assembly, and the signal output terminal is electrically connected to the voltage conversion module, so as to sample the voltage signal on the sampling capacitor assembly and transmit it to the voltage conversion module. A grounding terminal, which is used to connect to the ground wire in a multiphase power grid; The multiphase power grid includes multiple live wires, each of which is electrically connected to one end of a corresponding filter capacitor assembly. The other end of each filter capacitor assembly is electrically connected to the grounding terminal. Each filter capacitor assembly includes a first filter capacitor assembly and at least one second filter capacitor assembly. The sampling capacitor assembly is connected in parallel with the first filter capacitor assembly, and the capacity of the sampling capacitor assembly connected in parallel with the first filter capacitor assembly is different from the capacity of the second filter capacitor assembly.
2. The ground wire detection circuit for a multiphase power grid according to claim 1, characterized in that, There are multiple sampling modules, and the signal output terminal of each sampling module is electrically connected to the voltage conversion module; The sampling module includes a first sampling module and at least one second sampling module. The signal input terminal of the first sampling module is electrically connected to the sampling capacitor component, and the signal input terminal of each second sampling module is electrically connected to the corresponding second filter capacitor component.
3. The ground wire detection circuit for a multiphase power grid according to claim 1, characterized in that, The multiphase power grid is a two-phase power grid. The live wires include a first live wire and a second live wire. There is one second filter capacitor assembly. The first live wire is electrically connected to one end of the first filter capacitor assembly, and the other end of the first filter capacitor assembly is electrically connected to the ground terminal. The second live wire is electrically connected to one end of the second filter capacitor assembly, and the other end of the second filter capacitor assembly is electrically connected to the ground terminal.
4. The ground wire detection circuit for a multiphase power grid according to claim 1, characterized in that, The sampling module includes an operational amplifier follower unit, the input terminal of which is electrically connected to the signal input terminal, and the output terminal of which is electrically connected to the signal output terminal.
5. The ground wire detection circuit for a multiphase power grid according to claim 4, characterized in that, The sampling module also includes an isolation capacitor assembly, which is connected in series between the signal input terminal and the input terminal of the operational amplifier follower unit.
6. The ground wire detection circuit for a multiphase power grid according to claim 1, characterized in that, The capacitance of each of the filter capacitor components is the same.
7. The ground wire detection circuit for a multiphase power grid according to claim 1, characterized in that, The sampling capacitor assembly and each of the filtering capacitor assemblies have the same capacity.
8. The ground wire detection circuit for a multiphase power grid according to claim 1, characterized in that, The sampling capacitor assembly includes a sampling capacitor, which is a high-voltage capacitor.
9. The ground wire detection circuit for a multiphase power grid according to claim 1, characterized in that, Each of the filter capacitor components includes a corresponding filter capacitor, which is a high-voltage capacitor.
10. A ground wire detection device for a multiphase power grid, characterized in that, The ground detection circuit for a multiphase power grid as described in any one of claims 1 to 9.