Isolation grounding detection circuit and system
By designing an isolated ground detection circuit, the physical characteristics of the transformer are converted into detection signals by using square wave output modules and transistors, the problem of low protection level in the prior art is solved, and non-contact precision detection and high-level protection are achieved.
Patent Information
- Application Number
- CN202510204784.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-24
- Publication Date
- 2025-06-13
AI Technical Summary
The prior art failed to achieve non-isolated ground detection, resulting in low protection levels and unable to meet the internal isolation requirements in industrial standards.
An isolated ground detection circuit is designed, which sends a square wave signal to the transformer through a square wave output module, uses a transistor to convert the physical characteristics of the transformer into a detection signal, and judges whether the grounding of the device to be detected is normal through an external processor.
It realizes non-contact precision detection, effectively improves the protection level, and meets the needs of non-isolated grounding detection in industrial standards.
Smart Images
Figure CN120142997A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of grounding detection, and particularly relates to an isolated grounding detection circuit and system. Background Art
[0002] In modern society with highly concentrated resources, large and medium-sized high-power devices can be seen everywhere in industry and manufacturing. Such devices not only need to be regularly maintained and inspected to reduce the failure rate, but also have higher requirements for stability, reliability and safety. Among them, the grounding circuit, as an important barrier for safety protection, can timely eliminate and alarm when there is an internal grounding fault, short circuit or induced current in the device, ensuring the safety of device operators, and timely maintaining when a fault occurs to reduce the damage to valuable devices caused by internal induced current and the like.
[0003] The grounding detection of the prior art mainly judges by sending the outputs of two comparators to the MCU. Although the judgment method is simple, it is actually non-isolated, with a low protection level and does not match the internal isolation requirements of industrial standards. Summary of the Invention
[0004] In view of this, it is necessary to provide an isolated grounding detection circuit and system to solve the technical problem of low protection level caused by the failure to achieve non-isolated grounding detection in the prior art.
[0005] To solve the above technical problem, the present invention provides an isolated grounding detection circuit, including: A square wave output module, electrically connected to one end of the primary winding of a transformer inside the device to be detected, for outputting a detection square wave. Wherein, the primary winding of the transformer is used to receive the detection square wave and release electrical energy, and both ends of the secondary winding are electrically connected to the isolated ground and the chassis ground respectively; A triode, with the base electrically connected to one end of the primary winding, the collector electrically connected to an external processor, and the emitter electrically connected to the isolated ground, for receiving the electrical energy and converting it into a detection signal and then sending it to the external processor; The external processor is used to judge whether the grounding of the device to be detected is normal according to the detection signal.
[0006] In a possible implementation manner, the square wave output module includes: a hysteresis comparator circuit for continuously outputting a periodic square wave with alternating high and low levels.
[0007] In a possible implementation manner, the other end of the primary winding is electrically connected to the isolated ground; The collector of the triode is also electrically connected to the positive pole of an external power supply, and the emitter is electrically connected to the isolated ground.
[0008] In a possible implementation, the detection signal includes: a level signal generated at the collector of a triode after receiving the electric energy.
[0009] In a possible implementation, determining whether the grounding of the device to be detected is normal according to the detection signal includes: Extracting the conduction time of the triode according to the level signal; Judging whether the grounding of the device to be detected is normal based on the conduction time.
[0010] In a possible implementation, a first time threshold range and a second time threshold range are pre-set in the external processor.
[0011] In a possible implementation, when the external processor detects that the conduction time is within the first time threshold range, it is determined that the isolated ground and the chassis ground of the device to be detected are disconnected; When the external processor detects that the conduction time is within the second time threshold range, it is determined that the isolated ground and the chassis ground of the device to be detected are short-circuited.
[0012] In a possible implementation, the conduction time includes: the time when the level signal is at a low level.
[0013] The present invention also provides an isolation grounding detection system, including: The isolation grounding detection circuit in any one of the above device items; An MCU, electrically connected to the isolation grounding detection circuit, for obtaining the conduction time of the triode inside the isolation grounding detection circuit and judging whether the grounding of the device to be detected is normal according to the conduction time.
[0014] In a possible implementation, the MCU is electrically connected to the base of the triode.
[0015] The beneficial effects of the present invention are as follows: The isolation grounding detection circuit provided by the present invention first sends a square wave signal to the transformer through the square wave output module, conducts the triode connected to the primary winding of the transformer, and then according to the physical characteristics that when the secondary of the transformer is short-circuited, the primary winding of the transformer is charged more and needs to release more energy, and when the secondary of the transformer is short-circuited, the primary winding of the transformer is charged less and needs to release less energy, and converts its physical characteristics into a detection signal through the triode and sends it to the external processor, thereby realizing non-contact precise detection and effectively solving the technical problem of low protection level in the prior art due to the failure to realize non-isolated grounding detection. Description of the Drawings To more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the accompanying drawings required for the description of the embodiments. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For those skilled in the art, without creative efforts, other accompanying drawings can be obtained based on these drawings.
[0016] Figure 1 FIG. 4 is a schematic structural diagram of an embodiment of the isolation grounding detection circuit provided by the present invention; Figure 2 FIG. 7 is a schematic flow diagram of an embodiment of the internal structure of the isolation grounding detection circuit provided by the present invention; Figure 3 FIG. 10 is a schematic waveform diagram of an embodiment of the collector level of a triode when the normal isolation ground and the chassis ground are disconnected provided by the present invention; Figure 4 FIG. 13 is a schematic waveform diagram of an embodiment of the collector level of a triode when the negative power supply is short-circuited to the ground provided by the present invention; Figure 5 FIG. 16 is a schematic structural diagram of an embodiment of the isolation grounding detection system provided by the present invention. Detailed Embodiments
[0017] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative efforts fall within the protection scope of the present invention.
[0018] In the description of the embodiments of the present invention, unless otherwise specified, "a plurality of" means two or more. "And / or" describes the association relationship of associated objects, indicating that three relationships can exist. For example: A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone.
[0019] The descriptions such as "first", "second", etc. involved in the embodiments of the present invention are only for descriptive purposes, and cannot be understood as indicating or implying their relative importance or implicitly indicating the quantity of the indicated technical features. Therefore, the technical features defined with "first" and "second" may explicitly or implicitly include at least one of such features.
[0020] References to "embodiments" in this specification mean that specific features, structures, or characteristics described in connection with the embodiments can be included in at least one embodiment of the invention. The phrase appears in various places in the specification and does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art will explicitly and implicitly understand that the embodiments described herein can be combined with other embodiments.
[0021] Before presenting the embodiments, the following terms are explained.
[0022] Isolated ground: A design method for isolating two parts of a circuit. Usually in a circuit, the entire circuit is divided into a high-voltage side and a low-voltage side, and isolated ground is used to prevent electromagnetic interference and error transmission between the two.
[0023] Chassis ground: A grounding method that forms a good conductive connection between the normally non-energized metal parts (such as the cabinet shell, console shell, etc.) in the device system and the ground to ensure the safety of the device and personnel. It is also called safety ground or chassis safety ground.
[0024] Such as Figure 1 , the present invention provides an isolated ground detection circuit 10, comprising: A square wave output module 110, electrically connected to one end of the primary winding of a transformer 20 inside the device to be detected, for outputting a detection square wave. Wherein, the primary winding of the transformer is used to receive the detection square wave and release electrical energy, and both ends of the secondary winding are electrically connected to the isolated ground and the chassis ground respectively; It should be noted that the transformer has the following physical characteristics: When the secondary of the transformer is short-circuited, the primary winding of the transformer charges more and needs to release more energy; When the secondary of the transformer is short-circuited, the primary winding of the transformer charges less and needs to release less energy.
[0025] A triode 120, with its base electrically connected to one end of the primary winding, its collector electrically connected to an external processor, and its emitter electrically connected to the isolated ground, for receiving electrical energy and converting it into a detection signal and then sending it to the external processor.
[0026] Furthermore, the triode has three basic operating modes: (1) Cut-off mode: The triode is completely turned off, the base current I B = 0, the collector current I C = 0, and no current flows between the collector and the emitter. (2) Saturation mode: The triode is completely turned on, the collector current I C reaches the maximum value, and at this time the collector-emitter voltage V CE is very low (usually only a few hundred millivolts). (3) Linear amplification mode: The triode operates in the amplification region, and the base current I B controls the collector current I C , and I C = βI B (β is the current amplification factor).
[0027] Since the triode 130 is electrically connected to the primary winding of the transformer 120, the time when the triode is in the amplification or saturation state will also change following the discharge state of the primary winding of the transformer 120.
[0028] When the triode is in the saturation mode, the collector current I C reaches the maximum value, and the collector-emitter voltage V CE is very low (close to 0). In this case, if the emitter is grounded (0V), the collector level can be regarded as a low level.
[0029] The external processor is used to judge whether the grounding of the device to be detected is normal according to the detection signal.
[0030] It should be noted that the present invention is applied to large and medium-sized devices with high power. When in use, the present invention is integrated on the circuit board card and embedded in the device to be detected. The setting of each device inside the circuit of the present invention can completely isolate the chassis from the circuit board card, with a higher protection level.
[0031] Compared with the prior art, for the isolation grounding detection circuit provided by the present invention, first, a square wave output module sends a square wave signal to the transformer, conducts the triode connected to the primary winding of the transformer, and then, according to the physical characteristics that when the secondary of the transformer is short-circuited, the primary winding of the transformer is charged more and needs to release more energy, and when the secondary of the transformer is short-circuited, the primary winding of the transformer is charged less and needs to release less energy, and through the triode, its physical characteristics are converted into a detection signal and sent to the external processor, thereby realizing non-contact precise detection, and effectively solving the technical problem of low protection level in the prior art due to the failure to achieve non-isolated grounding detection.
[0032] In a possible implementation manner, the square wave output module 110 includes: a hysteresis comparator circuit for outputting a periodic square wave with alternating high and low levels.
[0033] Preferably, the square wave output module can adopt an LMV358 chip, such as Figure 2As shown, the chip provides a dual-channel comparator circuit. In the part of the positive terminal of comparator U10A, a reference input is provided by resistors R59 and R50, and then connected to the output terminal of comparator U10A through resistor R60 to form a positive feedback. At the same time, a capacitor C37 is connected to the isolated ground at the negative terminal of the comparator and connected to the output terminal through resistor R67 to provide a charging and discharging path for capacitor C37. Thus, the circuit forms a hysteresis comparator.
[0034] The specific process is as follows: At the beginning of power-on (if the charging effect of C37 is first ignored before power-on), the output of the comparator gradually increases. At this time, the output terminal also continuously charges capacitor C37 through R67, and V c will continue to charge until it becomes slightly greater than the threshold voltage V of the comparator p . At this time, the comparator output V OUT will be pulled down to the negative rail V SS (the negative terminal of the comparator input is greater than the positive terminal, and the output flips to low), and V c will start to discharge. V c will continue to discharge until it is lower than the voltage at V p . Then, the output will be driven back to the positive power rail V DD (the negative terminal of the comparator input is less than the positive terminal, and the output flips to high). This process will continue periodically, thus generating a square wave at the output terminal of the operational amplifier.
[0035] In a possible implementation, the other end of the primary winding is electrically connected to the isolated ground; The collector of the triode is also electrically connected to the positive pole of the external power supply, and the emitter is electrically connected to the isolated ground.
[0036] In a possible implementation, the detection signal includes: the level signal generated at the collector of triode 130 after receiving electrical energy.
[0037] In a possible implementation, judging whether the grounding of the device to be detected is normal according to the detection signal includes: extracting the conduction time of triode 130 according to the level signal; judging whether the grounding of the device to be detected is normal based on the conduction time.
[0038] In a possible implementation, a first time threshold range and a second time threshold range are preset in the processor.
[0039] In a possible implementation, when the processor detects that the conduction time is within the first time threshold range, it is judged that the isolated ground of the device to be detected is disconnected from the chassis ground; When the processor detects that the conduction time is within the second time threshold range, it is judged that the isolated ground of the device to be detected is short-circuited to the chassis ground.
[0040] In a possible implementation, the conduction time includes: the time when the level signal is at a low level.
[0041] It can be understood that when the triode is in the saturation mode, the collector current I C reaches the maximum value, and the collector-emitter voltage V CE is very low (close to 0). In this case, if the emitter is grounded (0V), the collector level can be regarded as a low level. Therefore, the present invention can convert the energy release situation of the primary winding of the transformer into the level waveform on the collector of the triode, and then extract the conduction time of the triode from the level waveform through the processor, and then judge the grounding situation of the device to be detected according to the conduction time, while realizing isolation detection, reducing the hardware cost required for detection and improving the detection accuracy.
[0042] Furthermore, as Figure 2 shown, JD_CTL is the detection signal output by the IO port, and a high-level pulse signal of 10 ms is turned on when detection is required; JD_CHECK_CTL is the input interrupt detection port of the external processor.
[0043] When the isolated ground GL_GND is open-circuited with the chassis ground EARTH, at this time the secondary of the transformer is in an open state, the primary of the transformer is charged more, so more energy needs to be released, and the time when the triode 130 is in the amplification or saturation state is longer, so the level state of the collector of the triode 130 is at a low level for a longer time.
[0044] Similarly, when there is a short circuit, the secondary of the transformer is in a short-circuit state, the primary of the transformer is charged less, so less energy needs to be released, the time when the triode 130 is in the amplification or saturation state is short, and the time when the level state of the collector of the triode 130 is at a low level is also short. Therefore, the processor can detect the grounding fault by judging the time of the low level at the JD_CHECK port.
[0045] Exemplarily, as Figure 3 shown, when the normal isolated ground is open-circuited with the chassis ground, the low-level signal appears at -316.000000 - 304.000000 us, then the time when the interrupt detection pin can detect the low-level signal is about 620 us; As Figure 4 shown, when the negative pole of the power supply is short-circuited to the ground, the low-level signal appears at -10.000000 - 96.000000 us, then the time when the interrupt detection pin can detect the low-level signal is about 106 us.
[0046] As Figure 5 , the present invention also provides an isolated grounding detection system, including: The isolation grounding detection circuit 10 of any one of the above device items; The MCU 20, electrically connected to the isolation grounding detection circuit 10, is configured to obtain the conduction time of the triode inside the isolation grounding detection circuit 10, and determine whether the grounding of the device to be detected is normal according to the conduction time.
[0047] In a possible implementation, the MCU is electrically connected to the base of the triode.
[0048] Those skilled in the art can understand that all or part of the processes for implementing the methods of the above embodiments can be completed by instructing relevant hardware (such as a processor, a controller, etc.) through a computer program, and the computer program can be stored in a computer-readable storage medium. Among them, the computer-readable storage medium is a magnetic disk, an optical disc, a read-only memory, or a random access memory, etc.
[0049] The above has introduced in detail an isolation grounding detection circuit and system provided by the present invention. Specific examples are used in this article to elaborate on the principle and implementation manner of the present invention. The description of the above embodiments is only used to help understand the method and its core idea of the present invention; at the same time, for those skilled in the art, according to the idea of the present invention, there will be changes in the specific implementation manner and application scope. In summary, the content of this specification should not be construed as a limitation to the present invention.
Claims
1. An isolated ground detection circuit, characterized in that: include: A square wave output module is electrically connected to one end of the primary winding of the transformer inside the device to be detected, and is used to output a detection square wave, wherein the primary winding of the transformer is used to receive the detection square wave and release electrical energy, and the two ends of the secondary winding are electrically connected to the isolation ground and the casing ground respectively; A transistor, the base of which is electrically connected to one end of the primary winding, the collector of which is electrically connected to the external processor, and the emitter of which is electrically connected to the isolated ground, for receiving the electric energy and converting it into a detection signal and then sending it to the external processor; The external processor is used to determine whether the grounding of the device to be detected is normal according to the detection signal.
2. The isolated grounding detection circuit according to claim 1, characterized in that: The square wave output module comprises: a hysteresis comparator circuit, which is used for continuously outputting a periodic square wave with alternating high and low levels.
3. The isolated grounding detection circuit according to claim 1, characterized in that: The other end of the primary winding is electrically connected to an isolation ground; The collector of the triode is also electrically connected to the positive electrode of the external power supply.
4. The isolated grounding detection circuit according to claim 1, characterized in that: The detection signal includes: a level signal generated on the collector after the transistor receives the electric energy.
5. The isolated grounding detection circuit according to claim 4, characterized in that: The step of judging whether the grounding of the device to be detected is normal according to the detection signal includes: Extracting the conduction time of the transistor according to the level signal; Whether the grounding of the device to be detected is normal is judged based on the conduction time.
6. The isolated grounding detection circuit according to claim 5, characterized in that: The external processor is pre-set with a first time threshold range and a second time threshold range.
7. The isolated grounding detection circuit according to claim 6, characterized in that: When the external processor detects that the conduction time is within a first time threshold range, determining that the isolation ground of the device to be detected is disconnected from the housing ground; When the external processor detects that the conduction time is within a second time threshold range, it is determined that the isolation ground and the housing ground of the device to be detected are short-circuited.
8. The isolated ground detection circuit according to claim 5, characterized in that: The on-time includes: the time during which the level signal is at a low level.
9. An isolated grounding detection system, characterized in that: include: The isolated ground detection circuit according to any one of claims 1 to 8; The MCU is electrically connected to the isolated grounding detection circuit and is used to obtain the conduction time of the transistor inside the isolated grounding detection circuit and determine whether the grounding of the device to be detected is normal according to the conduction time.
10. The isolated grounding detection system according to claim 9, characterized in that: The MCU is electrically connected to the base of the transistor.