Connection control circuit for isolating ground from ground

Abstract

The utility model discloses a connection control circuit for an isolation ground and the ground, relates to the technical field of power electronics, and can solve the problems that the connection mode between the isolation ground and the ground is fixed and uncontrollable, and electrostatic accumulation, electromagnetic interference (EM I), current leakage risks and potential safety hazards are easily caused. On and off of the switch module are controlled through the control module, flexible connection between the isolation ground and the ground is achieved, and the purposes of electrostatic discharge, electromagnetic interference prevention and system safety and stability improvement are achieved. According to the application, the connection state between the isolation ground and the ground can be flexibly controlled according to actual requirements, so that risks such as static accumulation and electromagnetic interference are reduced on the premise of ensuring the safety of equipment, and the operation reliability and safety of the equipment are improved.

Description

Technical Field

[0001] This application relates to the field of power electronic systems technology, and in particular to a connection control circuit between an isolated ground and the earth. Background Technology

[0002] In fields such as electronic equipment, industrial control systems, communication equipment, and test and measurement equipment, the connection between the internal grounding (also known as floating ground) and the external earth (grounding system) is often involved. Grounding is typically used to achieve electrical isolation to avoid the effects of external interference, electromagnetic interference, or ground loops. However, while grounding improves the equipment's immunity and safety, it can also lead to the accumulation of static charge. In certain special cases, selective connection to the earth may be necessary to release static electricity or suppress potential differences, thereby preventing electrical safety hazards or equipment damage.

[0003] In existing technologies, the connection between the isolation ground and the earth is usually a fixed hard connection or a manually operated mechanical switch connection. However, existing connection methods lack flexibility, cannot be automatically controlled, are prone to ground loop interference, cannot effectively release static electricity accumulation, and have the risk of human error, which reduces the equipment's anti-interference ability and safety.

[0004] The information disclosed in this background section is included only to enhance the understanding of the context of this disclosure, and therefore may contain information that does not constitute prior art known to those skilled in the art. Utility Model Content

[0005] This application provides a connection control circuit between an isolated ground and the earth to solve the problems of fixed and uncontrollable connection between the isolated ground and the earth, which easily leads to static electricity accumulation, electromagnetic interference, leakage current risk and safety hazards.

[0006] The technical solution adopted in this application is as follows:

[0007] In a first aspect, this application provides a connection control circuit between an isolated ground and the earth, the circuit comprising:

[0008] The switch module is connected between the isolation ground and the earth and is used to control the connection status between the isolation ground and the earth.

[0009] The control module, connected to the switch module, is used to control the switching state of the switch module based on the input selection signal, so that the isolated ground and the earth are in a connected state corresponding to the selection signal.

[0010] This application achieves flexible control of the connection status between the isolated ground and the earth by setting up a switch module and a control module. It can dynamically adjust the connection or disconnection status between the isolated ground and the earth based on the input selection signal according to actual needs or system operating conditions, thereby improving the flexibility and reliability of the isolated ground connection control and facilitating automated management and intelligent control.

[0011] As one possible implementation, the switch module includes a first switch and a second switch, wherein:

[0012] The first terminal of the first switch is connected to the isolation ground;

[0013] The first terminal of the second switch is connected to the ground;

[0014] The second terminal of the first switch is connected to the second terminal of the second switch.

[0015] This application uses two switches to flexibly switch between the isolation ground and the earth connection method, effectively reducing potential conflicts and electromagnetic interference, and improving system safety, reliability and electromagnetic compatibility.

[0016] As one possible implementation, the first switch is a first relay switch, and the second switch is a second relay switch;

[0017] The first relay switch and the second relay switch are both controlled by the relay coil.

[0018] This application achieves consistency and synchronization of switch actions by implementing the first switch and the second switch as a first relay switch and a second relay switch, respectively, and by having both relay switches simultaneously controlled by the same relay coil. When the relay coil is activated, the first relay switch and the second relay switch can open or close simultaneously, thereby establishing a clear connection or disconnection state between the isolation ground and the earth. This effectively avoids the uncertainty of the connection state that may be caused by delays or asynchrony in switch actions, improves the reliability of system control, and reduces the risk of malfunction.

[0019] As one possible implementation, the circuit also includes an electrostatic discharge (ESD) protection module, wherein:

[0020] An electrostatic discharge protection module is connected in series between the second terminal of the first switch and the second terminal of the second switch to prevent static electricity accumulation.

[0021] This application, by connecting an electrostatic protection module in series between the second terminal of the first switch and the second terminal of the second switch, can effectively prevent the accumulation of static electricity between the isolation ground and the earth or the impact of instantaneous high-voltage static electricity, protect sensitive devices and circuits in the system from electrostatic damage, and improve the reliability and safety of the system.

[0022] As one possible implementation, the electrostatic discharge (ESD) protection module includes an ESD protection resistor and an ESD protection capacitor connected in parallel with the ESD protection resistor.

[0023] This electrostatic discharge (ESD) protection module has a simple structure, low cost, and good ESD discharge effect, which can effectively improve the anti-static performance and reliability of the circuit, and has strong engineering practicality and application advantages.

[0024] As one possible implementation, the control module includes a third switch, wherein:

[0025] The third switch and relay coil are connected in series between the positive and negative terminals of the power supply.

[0026] This application achieves effective control of the relay coil by setting a third switch in the control module and connecting the third switch in series with the relay coil between the positive and negative terminals of the power supply.

[0027] As one possible implementation, the third switch is an NMOS transistor, and the control module also includes voltage divider resistors and pull-down resistors, wherein:

[0028] The gate of the NMOS transistor is connected to the first level signal via a voltage divider resistor;

[0029] The gate of the NMOS transistor is also connected to the negative terminal of the power supply via a pull-down resistor.

[0030] This application implements the third switch as an NMOS transistor and sets voltage divider resistors and pull-down resistors, which can effectively prevent the gate from floating and avoid malfunctions. The structure is simple, stable and reliable, and can effectively control the conduction and cutoff of the NMOS transistor.

[0031] As one possible implementation, the third switch is a PMOS transistor, and the control module also includes a pull-up resistor, wherein:

[0032] The gate of the PMOS transistor is connected to a second-level signal;

[0033] The gate of the PMOS transistor is connected to the positive terminal of the power supply via a pull-up resistor.

[0034] This application uses a PMOS transistor and a pull-up resistor to control the relay coil, which can effectively prevent the gate from floating and avoid malfunctions. The structure is simple, stable and reliable, and can effectively control the conduction and cutoff of the PMOS transistor.

[0035] As one possible implementation, the control module also includes at least one filter capacitor, wherein:

[0036] The two ends of the filter capacitor are connected to the positive and negative terminals of the power supply, respectively.

[0037] This application improves the stability and anti-interference capability of the power supply and control circuit by setting a filter capacitor between the positive and negative terminals of the power supply, protects key components, and enhances the overall reliability and stability of the system.

[0038] As one possible implementation, the control module also includes a breakdown protection component connected in parallel with the relay coil to prevent current from breaking down the third switch.

[0039] This application effectively protects the third switching device and prevents current or voltage breakdown by connecting a breakdown protection component in parallel across the relay coil.

[0040] As one possible implementation, the breakdown protection component is a high-speed switching diode, with the anode of the high-speed switching diode connected to the first terminal of the relay coil and the cathode of the high-speed switching diode connected to the second terminal of the relay coil.

[0041] The first end of the relay coil is connected to the negative terminal of the power supply via a third switch, and the second end of the relay coil is connected to the positive terminal of the power supply; or, the first end of the relay coil is connected to the negative terminal of the power supply, and the second end of the relay coil is connected to the positive terminal of the power supply via a third switch.

[0042] This application uses a high-speed switching diode connected in parallel with a relay coil, which can effectively protect the third switching device and prevent current and voltage breakdown.

[0043] Other advantages, objectives and features of this application will be partly apparent from the description below, and partly understood by those skilled in the art through study and practice of this application. Attached Figure Description

[0044] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0045] Figure 1 This is one of the structural schematic diagrams of a connection control circuit between an isolated ground and the earth provided in an embodiment of this application;

[0046] Figure 2 This is a second schematic diagram of the structure of a connection control circuit between an isolated ground and the earth provided in an embodiment of this application. Detailed Implementation

[0047] To facilitate understanding of this application, a more comprehensive description will be provided below with reference to the accompanying drawings. The drawings illustrate typical embodiments of this application. However, this application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to make the disclosure of this application more thorough and complete. It should be understood that the embodiments of this application and the specific features therein are detailed descriptions of the technical solutions of this application, and not limitations thereof. Where there is no conflict, the embodiments of this application and the technical features therein can be combined with each other.

[0048] The following sections provide detailed descriptions of each example. It should be noted that the order in which the embodiments are described is not intended to limit the priority of the embodiments.

[0049] Please see Figure 1 , Figure 1 This paper shows a schematic diagram of the structure of a connection control circuit between an isolated ground and the earth provided in an embodiment of this application.

[0050] like Figure 1 As shown, the circuit includes:

[0051] Switch module 200 is connected between isolation ground ISO_GND and earth EARTH to control the connection status between isolation ground ISO_GND and earth EARTH;

[0052] The control module 100, connected to the switch module 200, is used to control the switching state of the switch module 200 based on the input selection signal, so that the isolation ground ISO_GND and the earth EARTH are in a connected state corresponding to the selection signal.

[0053] For example, the switch module 200 is disposed between the isolation ground ISO_GND and the earth ground to control whether the isolation ground ISO_GND and the earth ground are conductive. When the switch module 200 is in the closed state, the isolation ground ISO_GND and the earth ground are conductive and have the same potential; when the switch module 200 is in the open state, the isolation ground ISO_GND and the earth ground are isolated, and the potentials between the isolation ground ISO_GND and the earth ground are no longer directly related.

[0054] Meanwhile, the control module 100 is connected to the switch module 200 and receives selection signals from external input. Based on the state of the selection signal, the control module 100 controls the switch module 200 to turn on or off, thereby achieving different connection modes between the isolation ground ISO_GND and the earth.

[0055] For example, when the selection signal is high, the control module 100 drives the switch module 200 to turn on, and the isolation ground ISO_GND is directly connected to the earth ground. At this time, the isolation ground ISO_GND and the earth ground have the same potential, and the system is in a non-floating ground state.

[0056] When the selection signal is low, the control module 100 drives the switch module 200 to disconnect, and the isolation ground ISO_GND is isolated from the earth ground. At this time, the isolation ground ISO_GND is floating, and the system achieves electrical isolation between the isolation ground ISO_GND and the earth ground.

[0057] like Figure 2 As shown, Figure 2 This paper shows a schematic diagram of the connection control circuit between the isolation ground ISO_GND and the earth EARTH provided in an embodiment of this application.

[0058] In some embodiments, such as Figure 2 As shown, the switch module 200 includes a first switch K1(1) and a second switch K1(2). The first switch K1(1) has two ports (a first terminal and a second terminal), and the first terminal of the first switch K1(1) is connected to the isolation ground ISO_GND; the second switch K1(2) also has two ports (a first terminal and a second terminal), and the first terminal of the second switch K1(2) is connected to the earth EARTH; the second terminal of the first switch K1(1) is connected to the second terminal of the second switch K1(2). Through this connection method, the switch module 200 can easily and flexibly control the connection state between the isolation ground ISO_GND and the earth EARTH, specifically as follows:

[0059] When both the first switch K1(1) and the second switch K1(2) are closed, the isolation ground ISO_GND and the earth EARTH are electrically connected through the first switch K1(1) and the second switch K1(2), and the isolation ground ISO_GND is no longer floating.

[0060] When at least one of the first switch K1(1) and / or the second switch K1(2) is in the open state, the electrical connection between the isolation ground ISO_GND and the earth EARTH is cut off, the isolation ground ISO_GND is isolated from the earth EARTH, and the isolation ground ISO_GND is a floating ground.

[0061] The control module 100 uniformly controls the switching states of the first switch K1(1) and the second switch K1(2) based on the externally input selection signal. For example:

[0062] When the selection signal indicates that the isolation ground ISO_GND needs to be connected to the earth EARTH, the control module 100 simultaneously closes the first switch K1(1) and the second switch K1(2), so that the isolation ground ISO_GND and the earth EARTH are connected through a common node;

[0063] When the selection signal indicates that the isolation ground ISO_GND and the earth EARTH need to be isolated, the control module 100 will open at least one switch (first switch K1(1) or second switch K1(2)), the connection path between the isolation ground ISO_GND and the earth EARTH will be cut off, and the isolation ground ISO_GND will be in a floating state.

[0064] It should be noted that, under normal circumstances, in order to ensure timely disconnection and avoid safety hazards, the first switch K1(1) and the second switch K1(2) are synchronous switches (i.e., they are disconnected and connected at the same time).

[0065] In some embodiments, the first switch K1(1) is a first relay switch, and the second switch K1(2) is a second relay switch; the first relay switch and the second relay switch are both controlled by the relay coil K1(3), that is, they share a single relay coil K1(3) for control. When the relay coil K1(3) is energized, the first relay switch and the second relay switch are closed simultaneously, and the isolation ground ISO_GND is connected to the earth EARTH through the two relay switches. At this time, the isolation ground ISO_GND is no longer floating, but is electrically connected to the earth EARTH. When the relay coil K1(3) is de-energized, the first relay switch and the second relay switch are opened simultaneously, the connection path between the isolation ground ISO_GND and the earth EARTH is cut off, the isolation ground ISO_GND is electrically isolated from the earth EARTH, and the isolation ground ISO_GND is in a floating state.

[0066] In some embodiments, the circuit further includes an electrostatic discharge (ESD) protection module. The path from isolation ground ISO_GND to earth is not directly connected through the two switching nodes, but is connected via the ESD protection module as an intermediate link, wherein:

[0067] The electrostatic protection module is connected in series between the second terminal of the first switch K1(1) and the second terminal of the second switch K1(2) to prevent the accumulation of static electricity.

[0068] This electrostatic discharge (ESD) protection module can effectively prevent or reduce high-voltage transient surges caused by static electricity accumulation, thereby protecting equipment safety and preventing damage or interference to precision measurement circuits or sensitive components from electrostatic discharge (ESD).

[0069] For example, a combination of a high-resistance resistor and a TVS diode can be used. A high-impedance resistor (e.g., 1MΩ to 10MΩ) can be used to slowly discharge static charge between the isolation ground (ISO_GND) and earth, preventing the continuous accumulation of electrostatic voltage. A transient voltage suppressor diode (TVS diode) is connected in parallel across the resistor to protect against high-voltage transients caused by electrostatic discharge. When the electrostatic voltage exceeds the breakdown voltage of the TVS diode, the TVS diode quickly conducts, releasing the electrostatic surge energy to earth and protecting subsequent circuitry.

[0070] See also Figure 2 In some embodiments, the electrostatic discharge (ESD) protection module includes an ESD protection resistor R3 (e.g., 1 MΩ to 10 MΩ) and an ESD protection capacitor C3 (e.g., a high-voltage ceramic capacitor in the range of several hundred pF to 0.1 μF) connected in parallel with the ESD protection resistor R3.

[0071] Understandably, the function of the electrostatic discharge (ESD) protection resistor R3 is to provide a high-impedance discharge path between the isolation ground ISO_GND and the earth, allowing the static charge accumulated on the isolation ground ISO_GND to be slowly discharged, preventing the electrostatic voltage from accumulating to a dangerous level that could damage the circuit. The ESD protection capacitor C3 is connected in parallel with the aforementioned ESD protection resistor R3 to provide a low-impedance AC path for rapid bypassing and releasing transient high-frequency interference or electrostatic discharge (ESD) energy, further improving the ESD protection performance.

[0072] In some embodiments, the control module 100 includes a third switch, and the third switch and a relay coil K1(3) are connected in series between the positive and negative terminals of the power supply. For example, when the third switch is closed, the power supply provides current to the relay coil K1(3), the relay coil K1(3) is energized and actuates, thereby causing the first switch K1(1) and the second switch K1(2) to close simultaneously; when the third switch is open, the relay coil K1(3) is de-energized, the relay coil K1(3) is reset, thereby causing the first switch K1(1) and the second switch K1(2) to open simultaneously.

[0073] It should be noted that the third switch can be an electronic switching device, such as a transistor, MOSFET or other electronic switching element, controlled by a microcontroller (MCU) or other logic control circuit. When the MCU or control logic issues an instruction, the third switch is controlled to close or open, thereby controlling whether the relay coil K1(3) is energized, and further controlling the connection status between the isolation ground ISO_GND and the earth ground EARTH.

[0074] It is understandable that the specific location of the third switch is not restricted, as long as it is connected in series in the power supply path of the relay coil K1(3). Therefore, there are two possible connection methods for the third switch:

[0075] One connection method is as follows: the first end of the relay coil K1(3) is connected to the negative terminal of the power supply via the third switch; the second end of the relay coil K1(3) is directly connected to the positive terminal of the power supply.

[0076] The second connection method is as follows: the first end of the relay coil K1(3) is directly connected to the negative terminal of the power supply; the second end of the relay coil K1(3) is connected to the positive terminal of the power supply via the third switch.

[0077] like Figure 2 As shown, this illustrates connection method one. In this method, the third switch can be an NMOS transistor Q1, and the control module 100 further includes a voltage divider resistor R1 and a pull-down resistor R2. The drain of the NMOS transistor Q1 is connected to the positive terminal of the power supply via a relay coil K1 (3), and the source of the NMOS transistor Q1 is connected to the negative terminal of the power supply (e.g., ground GND). The gate of the NMOS transistor Q1 is connected to a first-level signal (e.g., a control signal output by a microcontroller MCU) via the voltage divider resistor R1 to control the conduction or turn-off of the NMOS transistor Q1. The gate of the NMOS transistor Q1 is also connected to the negative terminal of the power supply (e.g., ground GND) via the pull-down resistor R2 to ensure that when the first-level signal is floating or not output, the gate potential of the NMOS transistor Q1 is clearly in a low-level state, thus preventing the NMOS transistor Q1 from being mistakenly turned on.

[0078] For example, when the first level signal (MCU control output signal) is high (e.g., 3.3V or 5V), the first level signal is applied to the gate of NMOS transistor Q1 through voltage divider resistor R1. The gate voltage rises to above the turn-on threshold voltage of NMOS transistor Q1 (relative to the source 0V potential). NMOS transistor Q1 turns on when the gate-source voltage is high enough, thus forming a low-impedance path between the source and drain. At this time, a current loop is formed between one end of relay coil K1(3) (connected to the positive terminal of the power supply) and ground GND through NMOS transistor Q1. Relay coil K1(3) is energized and drives its internal mechanical structure to move, thereby realizing the closing or opening of the relay contacts, and further controlling the corresponding actions of the first switch K1(1) and the second switch K1(2).

[0079] When the first level signal (MCU control output signal) is low (0V or close to ground potential), the gate voltage of NMOS transistor Q1 is close to 0V. The gate-source voltage is less than the turn-on threshold voltage of NMOS transistor Q1, so NMOS transistor Q1 is in the off state, and there is a high impedance between the source and drain. At this time, the relay coil K1(3) cannot form an effective circuit, the coil current is zero, the relay coil K1(3) is de-energized, the internal contacts of the relay are reset, and the first switch K1(1) and the second switch K1(2) return to their initial state.

[0080] When the first level signal (MCU control output signal) is floating or not output, the gate of NMOS transistor Q1 is connected to ground GND via pull-down resistor R2. Pull-down resistor R2 ensures that the gate voltage is pulled down to ground potential (0V), ensuring that NMOS transistor Q1 is stably in the off state. This avoids the gate voltage floating and causing NMOS transistor Q1 to be falsely turned on, prevents abnormal operation of relay coil K1(3), and ensures the stability and reliability of the circuit.

[0081] It should be noted that, for reference Figure 2 The first level signal can be output from the MCU to the NMOS transistor Q1 via the dry contact Dry and the voltage divider resistor R1. The dry contact Dry is essentially a switch connecting two conductive elements without providing any power. The dry contact Dry's output level is controlled by software, thus controlling the opening and closing of the relay. A high level input to the dry contact Dry turns on the NMOS transistor Q1, and a low level input turns it off.

[0082] In some embodiments, the third switch can also be implemented using connection method two. In this embodiment, the third switch can be implemented using a PMOS transistor. Similarly, the second level signal can also be received through the dry contact Dry. At this time, the control module 100 further includes a pull-up resistor, and the specific connection method is as follows: the drain of the PMOS transistor is connected to the negative terminal of the power supply via the relay coil K1 (3), and the source of the PMOS transistor is connected to the positive terminal of the power supply; the gate of the PMOS transistor is connected to the second level signal (e.g., a control signal output by a microcontroller MCU or other logic drive) to control the conduction or turn-off of the PMOS transistor; the gate of the PMOS transistor is also connected to the positive terminal of the power supply via the pull-up resistor to ensure that when the second level signal is not applied or is in a floating state, the gate is clearly in a high level state, and the PMOS transistor remains in a cut-off state to avoid misleading conduction.

[0083] For example, when the second level signal outputs a low level (e.g., 0V or near ground potential), the gate voltage of the PMOS transistor has a large voltage difference relative to the source voltage (+24V), so the PMOS transistor is turned on. The positive terminal of the power supply provides current to the relay coil K1 (3) through the PMOS transistor. The relay coil K1 (3) is energized and then controls the first switch K1 (1) and the second switch K1 (2) to close.

[0084] When the second level signal outputs a high level (for example, close to the positive voltage of the power supply 24V or the MCU output port is in a high impedance state), the gate voltage is close to the source voltage, the PMOS transistor is cut off, the relay coil K1(3) cannot obtain current, so the relay is de-energized and reset, and the first switch K1(1) and the second switch K1(2) are disconnected.

[0085] The pull-up resistor ensures that the gate voltage of the PMOS transistor remains at a high level (close to the supply voltage) when the second-level signal is not output or is floating, preventing the PMOS transistor from malfunctioning and improving the stability and reliability of the circuit.

[0086] In some embodiments, the control module 100 may further include at least one filter capacitor to improve the stability and anti-interference performance of the control module 100. The two ends of the filter capacitor are connected to the positive and negative terminals of the power supply, respectively, for filtering the power supply. It should be noted that in this embodiment, the filter capacitor can be one or more capacitors connected in parallel. See here for more details. Figure 2 For example, a 0.1uF small-capacity ceramic capacitor C1 can be used as a filter capacitor to filter out high-frequency noise, such as interference from the switching power supply; a 10nF large-capacity electrolytic capacitor C2 can be used as another filter capacitor to filter out low-frequency noise, such as pulsating DC after rectification.

[0087] In some embodiments, the control module 100 further includes a breakdown protection component, which is connected in parallel with the relay coil K1 (3). That is, the two ends of the breakdown protection component are respectively connected to the two ends of the relay coil K1 (3), specifically used to prevent the high voltage pulse generated when the current of the relay coil K1 (3) is quickly cut off from breaking down the third switch (such as NMOS transistor Q1).

[0088] When the third switch disconnects the current in the relay coil K1(3), a high back electromotive force (reverse high voltage pulse) will be generated on the coil. The anti-breakdown component will conduct at this time, forming an effective discharge channel to release the coil's stored energy, clamp or limit the high voltage spike within a safe level, and prevent the third switch from being damaged by high voltage breakdown.

[0089] Typically, the following components can be selected for breakdown protection: freewheeling diode (also known as flywheel diode or clamping diode), transient voltage suppressor diode (TVS diode), varistor or RC snubber circuit, etc.

[0090] In some embodiments, such as Figure 2 As shown, the anti-breakdown component can use a high-speed switching diode D1 as a freewheeling diode. The anode of the high-speed switching diode D1 is connected to the first end of the relay coil K1(3), and the cathode of the high-speed switching diode D1 is connected to the second end of the relay coil K1(3).

[0091] The first end of the relay coil K1(3) is the end connected to the negative terminal of the power supply; the second end of the relay coil K1(3) is the end connected to the positive terminal of the power supply. For example, in the first connection method, the first end of the relay coil K1(3) is the end connected to the drain of the NMOS transistor, and the second end of the relay coil K1(3) is the end connected to the positive terminal of the power supply. For another example, in the second connection method, the first end of the relay coil K1(3) is the end connected to the negative terminal of the power supply, and the second end of the relay coil K1(3) is the end connected to the drain of the PMOS transistor.

[0092] The high-speed switching diode D1 is connected in parallel with the relay coil K1(3) to provide a freewheeling path when the current of the relay coil K1(3) is quickly cut off, so as to prevent the generated high voltage reverse spike voltage from breaking down the third switch (such as MOSFET, transistor, etc.).

[0093] For example, when the third switch is turned on, the relay coil K1(3) is energized and operates; when the third switch is turned off, the reverse high voltage of the relay coil K1(3) forms a freewheeling circuit through the high-speed switching diode D1, thus protecting the third switch from breakdown damage.

[0094] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0095] It should be noted that when one component is referred to as "connecting" another component, it can be a direct connection to the other component or an indirect connection through an intermediary component.

[0096] It should be noted that, unless otherwise specified, the term "connected" or "linked" in this application includes not only directly connecting two entities, but also indirectly connecting them through other entities that have beneficial improvement effects.

[0097] The terms "first," "second," and other ordinal numbers used in this specification may be used to describe various constituent elements, but these constituent elements are not limited by these terms. The purpose of using these terms is solely to distinguish one constituent element from others. For example, without departing from the scope of the claims of this application, a first constituent element may be named a second constituent element, and similarly, a second constituent element may be named a first constituent element.

[0098] The terms “equal,” “identical,” “simultaneous,” or other similar expressions, not limited to absolute equality or identity in mathematical terms, can refer to similarity in an engineering sense or within an acceptable error range when implementing the rights described in this patent.

[0099] Numerous specific details are set forth in the specification provided herein. However, it will be understood that embodiments of this application may be practiced without these specific details. In some instances, well-known methods, structures, and techniques have not been shown in detail so as not to obscure the understanding of this specification.

[0100] Similarly, it should be understood that, in order to simplify this disclosure and aid in understanding one or more of the various aspects of the application, in the above description of exemplary embodiments of the application, various features of the application are sometimes grouped together in a single embodiment, figure, or description thereof. However, this approach to disclosure should not be construed as reflecting an intention that the claimed application requires more features than are expressly recited in each claim. Rather, as reflected in the following claims, the application aspect comprises fewer than all features of a single foregoing disclosed embodiment. Therefore, the claims following the detailed description are hereby expressly incorporated into that detailed description, wherein each claim itself is a separate embodiment of the application.

[0101] It should be noted that the above embodiments are illustrative of this application and not limiting of it, and that those skilled in the art can devise alternative embodiments without departing from the scope of the appended claims. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements.

[0102] The embodiments of this application have been described above with reference to the accompanying drawings. However, this application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many forms under the guidance of this application without departing from the spirit and scope of protection of the claims. All equivalent structural transformations made under the inventive concept of this application and using the content of this application's specification and drawings, or direct / indirect applications in other related technical fields, are included within the patent protection scope of this application.

Claims

1. A connection control circuit between an isolated ground and the earth, characterized in that, include: A switch module, connected between an isolation ground and the earth, is used to control the connection state between the isolation ground and the earth; A control module, connected to the switch module, is used to control the switching state of the switch module based on the input selection signal, so that the isolated ground and the ground are in a connected state corresponding to the selection signal.

2. The connection control circuit between the isolated ground and the earth according to claim 1, characterized in that, The switch module includes a first switch and a second switch, wherein: The first terminal of the first switch is connected to the isolation ground; The first terminal of the second switch is connected to the ground; The second end of the first switch is connected to the second end of the second switch.

3. The connection control circuit between the isolated ground and the earth according to claim 2, characterized in that, The first switch is a first relay switch, and the second switch is a second relay switch; Both the first relay switch and the second relay switch are controlled by the relay coil.

4. The connection control circuit between the isolated ground and the earth according to claim 2, characterized in that, It also includes an electrostatic discharge (ESD) protection module, in which: The electrostatic protection module is connected in series between the second terminal of the first switch and the second terminal of the second switch to prevent static electricity accumulation.

5. The connection control circuit between the isolated ground and the earth according to claim 4, characterized in that, The electrostatic discharge (ESD) protection module includes an ESD protection resistor and an ESD protection capacitor connected in parallel with the ESD protection resistor.

6. The connection control circuit between the isolated ground and the earth according to claim 3, characterized in that, The control module includes a third switch, wherein: The third switch and the relay coil are connected in series between the positive and negative terminals of the power supply.

7. The connection control circuit between the isolated ground and the earth according to claim 6, characterized in that, The third switch is an NMOS transistor, and the control module also includes voltage divider resistors and pull-down resistors, wherein: The gate of the NMOS transistor is connected to a first-level signal via the voltage divider resistor; The gate of the NMOS transistor is also connected to the negative terminal of the power supply via the pull-down resistor.

8. The connection control circuit between the isolated ground and the earth according to claim 6, characterized in that, The third switch is a PMOS transistor, and the control module also includes a pull-up resistor, wherein: The gate of the PMOS transistor is connected to a second-level signal; The gate of the PMOS transistor is connected to the positive terminal of the power supply via the pull-up resistor.

9. The connection control circuit between the isolated ground and the earth according to claim 6, characterized in that, The control module further includes at least one filter capacitor, wherein: The two ends of the filter capacitor are connected to the positive and negative terminals of the power supply, respectively.

10. The connection control circuit between the isolated ground and the earth according to claim 6, characterized in that, The control module also includes a breakdown protection component, which is connected in parallel with the relay coil to prevent current from breaking down the third switch.

11. The connection control circuit between the isolated ground and the earth according to claim 10, characterized in that, The breakdown protection component is a high-speed switching diode, the anode of which is connected to the first end of the relay coil, and the cathode of which is connected to the second end of the relay coil. The first end of the relay coil is connected to the negative terminal of the power supply via the third switch, and the second end of the relay coil is connected to the positive terminal of the power supply; or, the first end of the relay coil is connected to the negative terminal of the power supply, and the second end of the relay coil is connected to the positive terminal of the power supply via the third switch.

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