A line isolation detector

Abstract

The application discloses a line isolation detector for detecting leakage current of medical equipment in an operating room, comprising a power frequency detection unit, a control unit, an excitation coupling unit, a sampling isolation unit and a signal conditioning unit; the power frequency detection unit collects a power frequency signal of an external isolation transformer and transmits the power frequency signal to the control unit; the control unit generates a composite excitation signal according to the power frequency signal, and the excitation coupling unit couples and injects the composite excitation signal into a secondary side loop of the external isolation transformer; the sampling isolation unit collects a secondary side loop signal and realizes strong and weak electric isolation transmission; the signal conditioning unit sends the signal after noise reduction and shaping into the control unit; and the control unit analyzes and calculates according to the collected signal, and determines the ground insulation state and leakage fault of the secondary side loop of the isolation transformer online. The line isolation detector has the beneficial effect of accurate insulation detection.

Description

Technical Field

[0001] This invention relates to the field of leakage current detection technology, and more specifically to a line isolation detector. Background Technology

[0002] In special workplaces such as operating rooms and ICUs in the medical field, to avoid the risk of electric shock and ensure the electrical safety of medical equipment and personnel, isolation transformers are typically used to construct independent isolated power supply systems. To monitor the operational safety status of the isolated power supply circuit in real time, appropriate line isolation detection equipment is required to continuously monitor the leakage current and ground insulation condition of the secondary circuit of the isolation transformer.

[0003] In practical applications, existing similar testing equipment generally suffers from limited signal acquisition anti-interference capabilities and simple signal processing links, making it difficult to achieve high-precision online assessment of insulation status. At the same time, the overall hardware and software architecture is not well-designed, with poor strong and weak current isolation protection and signal excitation and sampling matching, making it difficult to meet the long-term monitoring requirements of high stability and high security in medical isolation power supply scenarios. Summary of the Invention

[0004] To overcome the above-mentioned shortcomings in the prior art, the present invention provides a line isolation detector with accurate insulation detection.

[0005] The technical solution of this invention is as follows: A line isolation detector for detecting leakage current in medical equipment in an operating room, comprising: Power frequency detection unit, control unit, excitation coupling unit, sampling isolation unit, and signal conditioning unit; The power frequency detection unit collects the power frequency signal from the external isolation transformer and transmits it to the control unit. The control unit generates a composite excitation signal based on the power frequency signal, which is then coupled and injected into the secondary circuit of the external isolation transformer by the excitation coupling unit. The sampling isolation unit acquires secondary circuit signals and achieves electrical isolation transmission between strong and weak currents. The signal conditioning unit performs noise reduction and shaping on the isolated signal before sending it to the control unit. The control unit analyzes and processes the collected signals to determine the insulation status to ground and leakage faults of the secondary circuit of the isolation transformer online.

[0006] Preferably, the control unit is able to identify the actual power frequency of the power grid and generate a composite excitation signal formed by superimposing sinusoidal components of the same power frequency and sinusoidal components of different power frequencies.

[0007] In any of the above schemes, it is preferred to further include an isolated power supply unit, which draws and regulates power from the independent winding of an external isolation transformer to provide isolated operating power to the system's digital control circuit and analog signal processing circuit respectively.

[0008] In any of the above schemes, it is preferred that the excitation coupling unit adopts an AC coupling isolation structure to isolate the DC electrical path between strong and weak currents.

[0009] In any of the above schemes, it is preferred that the sampling isolation unit uses a high-impedance pickup method to acquire the loop signal.

[0010] In any of the above solutions, it is preferred that the signal conditioning unit has high-frequency interference filtering and waveform amplitude normalization functions, and outputs a standard electrical signal that matches the sampling level requirements of the control unit.

[0011] In any of the above schemes, it is preferred that the control unit performs frequency decomposition on the received loop signal to separate the same power frequency component and different power frequency component, which serves as the basis for judging the insulation status.

[0012] In any of the above schemes, it is preferred that the control unit determines the insulation level of the secondary circuit by comparing the amplitude attenuation of the different power frequency components, so as to identify abnormal leakage conditions.

[0013] In any of the above solutions, it is preferred that the power frequency detection unit can be adapted to pick up power grid signals of different power frequency specifications and convert the original waveform into a standard signal that can be recognized by the control unit.

[0014] In any of the above solutions, it is preferred that the isolated power supply unit outputs unipolar DC voltage and bipolar DC voltage respectively to adapt to the different power supply requirements of the system's digital circuits and analog signal conditioning circuits.

[0015] The line isolation detector of this invention comprises a power frequency detection unit, a control unit, an excitation coupling unit, a sampling isolation unit, and a signal conditioning unit, forming a complete signal acquisition, excitation injection, isolation transmission, and signal processing chain. Each unit has a clear division of labor and cooperates sequentially. From acquiring the reference signal and sending the excitation signal to the circuit signal acquisition, isolation, and back-end conditioning optimization, the entire signal processing flow is complete and coherent, effectively reducing judgment errors caused by signal distortion and interference. This makes the detection and judgment of the insulation status and leakage faults of the secondary circuit of the isolation transformer more accurate and reliable. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the circuit connections of each unit of the line isolation detector of the present invention.

[0017] Figure 2This is a flowchart of the detection method of the line isolation detector of the present invention. Detailed Implementation

[0018] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] In the description of this invention, terms such as "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are used solely for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, terms such as "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0020] Example 1: This invention discloses a line isolation detector specifically designed for use in medical IT isolation power supply systems in critical medical areas such as operating rooms and ICUs. It provides 24 / 7 online detection and fault diagnosis of equipment leakage current and ground insulation status in the secondary circuit of the medical isolation transformer. Figure 1 , 2 As shown, the line isolation detector consists of a power frequency detection unit, a control unit, an excitation coupling unit, a sampling isolation unit, and a signal conditioning unit. Each unit works together to complete the entire process of signal acquisition, excitation injection, isolation transmission, signal conditioning, and calculation and analysis.

[0021] The line isolation detector in this embodiment relies on a medical standard isolation transformer to build its hardware infrastructure. The isolation transformer achieves magnetic isolation while simultaneously meeting the dual protection requirements of power supply isolation and signal isolation. The device can adapt to a wide range of AC input conditions from 120 to 240VAC and is compatible with the two internationally common power frequency specifications of 50Hz and 60Hz. It can adapt to the mains power parameter standards of different countries and regions, and its applicable scenarios cover the mainstream medical power supply environments worldwide. At the same time, the isolation transformer can be expanded to generate low-voltage isolation power supply and a dedicated excitation power supply of no less than 100V, providing a reliable energy source for system signal excitation, digital control and analog signal processing.

[0022] In this embodiment, the power frequency detection unit is adapted to connect with an external isolation transformer, enabling it to accurately pick up power grid signals of different power frequency specifications. It collects the power frequency signals during the operation of the external isolation transformer in real time, and converts and shapes the collected raw voltage waveforms into standard format signals that can be directly recognized by the control unit before stably transmitting them to the control unit. This provides the original reference for subsequent excitation signal generation, frequency reference calibration, and electrical parameter calculation.

[0023] In this embodiment, the control unit uses a high-performance microcontroller as the core processing hub. It can accurately identify the actual power frequency of the power grid based on the signal transmitted by the power frequency detection unit, and automatically generate a composite excitation signal formed by the superposition of sinusoidal components of the same power frequency and sinusoidal components of different power frequencies based on the identified real-time power frequency parameters. In practical applications, different frequency combinations can be matched according to the power grid conditions. For a 50Hz power grid, a superimposed excitation form of 50Hz and 72Hz can be used, and for a 60Hz power grid, a superimposed excitation form of 60Hz and 42Hz can be used. By using multi-frequency fusion output, the detection interference caused by the distributed capacitive reactance of the power grid itself is effectively suppressed, so that the insulation detection can still maintain stable and reliable detection accuracy under the complex electromagnetic conditions of medical applications.

[0024] In this embodiment, the composite excitation signal generated by the control unit is processed by the excitation coupling unit and then smoothly coupled into the secondary circuit of the external isolation transformer. The excitation coupling unit adopts an AC coupling isolation structure and can preferably use a CBB capacitor as the core coupling device. This can reliably isolate the DC electrical path between strong and weak circuits, prevent DC crosstalk from causing offset of the insulation detection baseline, and ensure that the excitation signal is safely and without interference injected into the circuit under test.

[0025] In this embodiment, the operating signal of the secondary circuit of the isolation transformer under test is picked up by the sampling isolation unit. The sampling isolation unit uses a high-impedance pickup method of not less than 50MΩ to collect the weak electrical signal of the circuit. While accurately acquiring the signal, it realizes electrical isolation transmission between strong and weak currents, effectively blocking the transmission of interference signals from the strong current side to the weak current control side, and ensuring the safe operation of the back-end circuit.

[0026] In this embodiment, the original signal, after being isolated and transmitted by the sampling isolation unit, is sent to the signal conditioning unit for optimization processing. The signal conditioning unit can employ a Salten signal conditioning unit. The key filter features a classic circuit architecture with dual functions of high-frequency interference filtering and waveform amplitude normalization. It can effectively filter out high-frequency noise mixed in the acquired signal, significantly improve the overall signal-to-noise ratio, and at the same time match and shape the waveform amplitude to finally output a standard electrical signal that fully matches the built-in sampling level requirements of the control unit for subsequent digital calculation and analysis.

[0027] In this embodiment, an isolated power supply unit is also provided to draw power from the independent winding position reserved by the external isolation transformer and perform voltage regulation and filtering. It independently provides a stable working power supply that is isolated from each other for the system's digital control circuit and analog signal processing circuit. The control unit belongs to the category of the system's digital control circuit. The power frequency detection unit, excitation coupling unit, sampling isolation unit, and signal conditioning unit together constitute the analog signal processing circuit of the whole machine. The isolated power supply unit can output unipolar DC voltage and bipolar DC voltage respectively, accurately adapting to the different power supply requirements between the system's digital circuit and analog signal conditioning circuit. The digital processing circuit uses a DC-DC BUCK step-down circuit to stably output a 5V unipolar DC voltage, while the analog signal processing circuit relies on an LDO low dropout linear regulator circuit to generate a ±10V bipolar DC voltage, meeting the different requirements of different functional circuits for power supply system and voltage level.

[0028] In this embodiment, after receiving the normalized standard signal output by the signal conditioning unit, the control unit can perform fine frequency decomposition on the received loop signal through a built-in algorithm to accurately separate the same power frequency component and different power frequency component contained in the signal, and use the two types of frequency components as the benchmark for judging the insulation status of the system; at the same time, by comparing the amplitude attenuation of the different power frequency component during the loop transmission process, the control unit can quantify the overall insulation degradation degree of the secondary circuit of the isolation transformer, and accurately capture and identify various leakage abnormal conditions in the loop.

[0029] In this embodiment, the control unit utilizes a built-in Fast Fourier Transform algorithm to perform signal analysis, parameter calculation, and logical judgment. It calculates key operating parameters in real time, such as power supply voltage, IT system insulation resistance to ground, and circuit leakage current, and identifies the insulation status to ground and potential leakage faults in the secondary circuit of the isolation transformer online. The device is also equipped with a human-machine interface system, featuring a capacitive touchscreen to create a visual operating interface. This interface supports real-time display of leakage current, leakage fault alarm output, historical operating data review, and online configuration of system operating parameters. The intuitive and simple interface facilitates daily monitoring and parameter adjustment by maintenance personnel. When the system detects that the circuit insulation level has dropped to a safe and dangerous threshold, it can promptly trigger an alarm, effectively mitigating the risks of electric shock and electrical fires in medical facilities and comprehensively ensuring the electrical safety of medical equipment and medical personnel.

[0030] The above-described embodiments are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A line isolation detector for detecting leakage current in medical equipment in an operating room, characterized in that, include: Power frequency detection unit, control unit, excitation coupling unit, sampling isolation unit, and signal conditioning unit; The power frequency detection unit collects the power frequency signal from the external isolation transformer and transmits it to the control unit. The control unit generates a composite excitation signal based on the power frequency signal, which is then coupled and injected into the secondary circuit of the external isolation transformer by the excitation coupling unit. The sampling isolation unit acquires secondary circuit signals and achieves electrical isolation transmission between strong and weak currents. The signal conditioning unit performs noise reduction and shaping on the isolated signal before sending it to the control unit. The control unit analyzes and processes the collected signals to determine the insulation status to ground and leakage faults of the secondary circuit of the isolation transformer online.

2. The line isolation detector according to claim 1, characterized in that, The control unit can identify the actual power frequency of the power grid and generate a composite excitation signal formed by superimposing sinusoidal components of the same power frequency and sinusoidal components of different power frequencies.

3. The line isolation detector according to claim 1, characterized in that, An isolated power supply unit is also provided, which draws and regulates the voltage from the independent winding of an external isolation transformer to provide isolated operating power to the system's digital control circuit and analog signal processing circuit respectively.

4. The line isolation detector according to claim 1, characterized in that, The excitation coupling unit adopts an AC coupling isolation structure to isolate the DC electrical path between strong and weak currents.

5. The line isolation detector according to claim 1, characterized in that, The sampling isolation unit uses a high-impedance pickup method to collect loop signals.

6. The line isolation detector according to claim 1, characterized in that, The signal conditioning unit has high-frequency interference filtering and waveform amplitude normalization functions, and outputs a standard electrical signal that matches the sampling level requirements of the control unit.

7. The line isolation detector according to claim 2, characterized in that, The control unit performs frequency decomposition on the received loop signal, separating the same power frequency component and the different power frequency component, which serve as the basis for judging the insulation status.

8. The line isolation detector according to claim 7, characterized in that, The control unit determines the insulation level of the secondary circuit by comparing the amplitude attenuation of different power frequency components, thereby identifying abnormal leakage conditions.

9. The line isolation detector according to claim 1, characterized in that, The power frequency detection unit can be adapted to pick up power grid signals of different power frequency specifications and convert the original waveform into a standard signal that can be recognized by the control unit.

10. The line isolation detector according to claim 3, characterized in that, The isolated power supply unit outputs unipolar DC voltage and bipolar DC voltage respectively, adapting to the different power supply requirements of the system's digital circuits and analog signal conditioning circuits.

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