An electrical fast transient burst filter circuit, inductive sensor circuit, and method

Abstract

The application provides an electric fast transient group pulse filter circuit, an inductive sensor circuit and a method. The circuit provided by the application comprises a filter module, an analog switch module and a control module. The control module is used for controlling the analog switch module to be disconnected within a first preset time length, and is also used for controlling the analog switch module to be conducted within a second preset time length. The first preset time length is determined according to a second resistor in the filter module and a first capacitor, and the second preset time length is determined according to a third resistor of the analog switch module and the first capacitor in the filter module. The filter module is used for receiving an interference signal, and charging when the analog switch module is disconnected and discharging when the analog switch module is conducted. The circuit of the application utilizes a simple circuit network, can be placed on a PCB, can completely filter out the interference signal and can reduce the influence on the switching frequency.

Description

Technical Field

[0001] This invention relates to the field of inductive sensor technology, and in particular to an electrical fast transient burst filter circuit, an inductive sensor circuit, and a method thereof. Background Technology

[0002] Electrical Fast Transient / Burst (EFT / Burst) tests can be used to simulate transient bursts of interference generated by relay or contactor switch action or lightning induction in real-world environments. This verifies the stability and reliability of equipment under such interference and prevents equipment malfunctions, data errors, or system crashes.

[0003] In EFT testing of inductor sensors, the most common way to introduce interference to the inductor sensor's power supply / signal is through abrupt changes in the ADC signal, causing the inductor sensor to output an incorrect signal. Conventional filtering methods are divided into hardware filtering and software filtering. Hardware filtering uses a large filter circuit to prevent common-mode interference signals from entering the inductor sensor's power supply / signal, thereby reducing interference. However, because it needs to filter signals across various frequency bands, the circuit is complex and large, making it unsuitable for placement on a PCB (Printed Circuit Board). Software filtering, on the other hand, can significantly affect the inductor sensor's switching frequency when the number of samples is high, while a low number of samples cannot completely filter out interference signals, still resulting in false triggering. Summary of the Invention

[0004] The purpose of this invention is to provide an electrical fast transient / burst filter circuit, an inductor sensor circuit, and a method to solve the technical problems in the prior art where the hardware circuit is too complex to be placed on a PCB and the software method reduces the switching frequency and does not completely filter out interference signals.

[0005] The technical solution of the present invention is as follows: an electrical fast transient / burst filter circuit is provided, including a filter module, an analog switch module, and a control module; The control module is used to control the analog switch module to disconnect within a first preset time period and to control the analog switch module to conduct within a second preset time period. The first preset time period is determined based on the second resistor and the first capacitor in the filter module, and the second preset time period is determined based on the third resistor in the analog switch module and the first capacitor in the filter module. The filtering module is used to receive interference signals, charge when the analog switch module is off, and discharge when the analog switch module is on.

[0006] Furthermore, the analog switch module also includes a switch chip, which is connected to the first terminal of the first capacitor through the third resistor. The second terminal of the first capacitor is grounded, and the first capacitor is connected in parallel with the second resistor. The first capacitor is charged when the analog switch module is off and discharged when the analog switch module is on.

[0007] Furthermore, the analog switch module also includes a fourth resistor, the first end of which is connected to the switch chip, and the second end of which is connected to the power supply voltage.

[0008] Furthermore, the filtering module also includes a first resistor, the first end of which is connected to the first end of the first capacitor.

[0009] Furthermore, the control module includes a main control chip, which is connected to the analog switch module to control the analog switch module to disconnect within a first preset time period and to control the analog switch module to turn on within a second preset time period.

[0010] Another technical solution of the present invention is as follows: an inductive sensor circuit is provided, including the electrical fast transient burst filter circuit and the oscillation circuit described in any of the above technical solutions, wherein the oscillation circuit is used to transmit an oscillation signal.

[0011] Furthermore, the oscillation circuit includes a first transistor, a second transistor, and a second capacitor. The first terminal of the first transistor is grounded, the second terminal of the first transistor is connected to the power supply voltage, the third terminal of the first transistor is connected to the third terminal of the second transistor, the second terminal of the second transistor is connected to the first terminal of the second transistor through the second capacitor, and the first terminal of the second transistor is also connected to the first terminal of the first capacitor.

[0012] Furthermore, the inductive sensor circuit also includes a signal distance adjustment circuit, which includes a variable resistor, a fifth resistor, and a sixth resistor. The first end of the variable resistor is connected to the first end of the second transistor through the sixth resistor, the second end of the variable resistor is grounded, and the variable resistor and the fifth resistor are connected in parallel.

[0013] Furthermore, the inductor sensor circuit also includes a dual series small-signal switching diode, the first end of which is connected to the first end of the second transistor, the second end of which is connected to the first end of the variable resistor, and the third end of which is connected to the first end of the first capacitor.

[0014] Another technical solution of the present invention is as follows: a method for filtering electrically fast transient bursts is provided, comprising: The control analog switch module is disconnected within a first preset time period, wherein the first preset time period is determined based on the second resistor and the first capacitor in the filter module; The filtering module receives interference signals and is charged when the analog switch module is disconnected. The control analog switch module is turned on within a second preset time period, wherein the second preset time period is determined based on the third resistor of the analog switch module and the first capacitor in the filter module; The filter module discharges when the analog switch module is turned on.

[0015] The beneficial effects of this invention are as follows: The control module is used to control the analog switch module to disconnect within a first preset time period and to control the analog switch module to conduct within a second preset time period, wherein the first preset time period is determined based on the second resistor and the first capacitor in the filter module, and the second preset time period is determined based on the third resistor in the analog switch module and the first capacitor in the filter module; the filter module is used to receive interference signals and to charge when the analog switch module is disconnected and to discharge when the analog switch module is conducted; by precisely coordinating the on / off timing of the analog switch module through the control module, the filter module absorbs EFT pulses by charging during the disconnection period. The alternating process of energy and discharge of interference charge during the conduction period suppresses signal abrupt changes at the ADC sampling end from the source. Unlike software filtering, which requires a large number of redundant samples to smooth interference, the above technical solution can completely filter out interference signals and reduce the impact on the switching frequency. Furthermore, the above technical solution abandons the traditional complex filter circuit and can effectively suppress EFT pulse groups using only a simple circuit network composed of a filter module, an analog switch module, and a control module. Since it does not need to deal with electromagnetic interference across the entire frequency band, the device parameters can be optimized and reduced, allowing it to be placed on a PCB and greatly reducing the PCB area occupied, thus solving the problem of limited space on high-density circuit boards. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of an electrically fast transient burst filter circuit provided in an embodiment of the present invention.

[0017] Figure 2 The circuit diagram of the electrically fast transient burst filter circuit provided in the embodiment of the present invention.

[0018] Figure 3 This is a schematic diagram of the ADC waveform provided in an embodiment of the present invention.

[0019] Figure 4 The circuit diagram of the control module provided in the embodiment of the present invention.

[0020] Figure 5 This is a schematic diagram of the structure of an inductor sensor circuit provided in an embodiment of the present invention.

[0021] Figure 6 The circuit diagram of the oscillation circuit provided in the embodiment of the present invention.

[0022] Figure 7 This is a schematic diagram of a signal distance adjustment circuit provided in an embodiment of the present invention.

[0023] Figure 8 The circuit diagram of the dual series small-signal switching diodes provided in the embodiment of the present invention.

[0024] Figure 9 This is a flowchart illustrating the electrically fast transient burst filtering method provided in an embodiment of the present invention. Detailed Implementation

[0025] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0026] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of the invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0027] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in sequences other than those illustrated or described herein.

[0028] Figure 1 This is a schematic diagram of the electrical fast transient / burst filter circuit according to an embodiment of the present invention. It should be noted that, if substantially the same result is achieved, the electrical fast transient / burst filter circuit of the present invention is not based on... Figure 1 The structures shown are limited. For example... Figure 1 As shown, the electrical fast transient / burst filter circuit 10 includes a filter module 11, an analog switch module 12, and a control module 13. The control module 13 is used to control the analog switch module 12 to disconnect within a first preset time period and to control the analog switch module 12 to conduct within a second preset time period. The first preset time period is determined based on the second resistor and the first capacitor in the filter module 11, and the second preset time period is determined based on the third resistor in the analog switch module 12 and the first capacitor in the filter module 11. The filtering module 11 is used to receive interference signals, charge when the analog switch module 12 is off, and discharge when the analog switch module 12 is on.

[0029] In one specific embodiment, the control module 13 can be a microcontroller unit (MCU). The control module 13 controls the conduction and cutoff of the analog switch module 12 by controlling the level of the pins (e.g., GPIO1) of the analog switch module 12. By controlling the width of the discharge time, the amplitude of the accumulated charge generated by the electrical fast transient pulse group is suppressed, and the amplitude of the ADC (analog-to-digital converter) interference is suppressed within the hysteresis value, thereby reducing sensor malfunctions.

[0030] In some embodiments, the analog switch module 12 further includes a switch chip, which is connected to a first terminal of the first capacitor through the third resistor. The second terminal of the first capacitor is grounded, and the first capacitor is connected in parallel with the second resistor. The first capacitor is charged when the analog switch module 12 is turned off and discharged when the analog switch module 12 is turned on.

[0031] It should be noted that the first preset duration is determined by multiplying the second resistor and the first capacitor, and the second preset duration is determined by multiplying the third resistor and the first capacitor. The sum of the first preset duration and the second preset duration can be greater than or equal to the output period of the inductive sensor.

[0032] In one specific embodiment, when determining the first preset duration and the second preset duration, the duration obtained by multiplying the second resistor and the first capacitor can be used as the charging time constant, and the first preset duration can be three times the charging time constant; the duration obtained by multiplying the third resistor and the first capacitor can be used as the discharging time constant, and the second preset duration can be three times the discharging time constant plus the preset third duration; wherein, the preset third duration is greater than three times the discharging time constant, and the addition of the preset third duration is to ensure more thorough discharging and suppress the cumulative charging of the sensor by the electrical fast transient pulse group.

[0033] In one specific embodiment, the circuit schematic of the electrical fast transient / burst filter circuit is as follows: Figure 2 As shown. Figure 2The switching chip U1 is connected to the control module 13 via pin GPIO1. The third resistor R3 is connected to the first terminal of the first capacitor C1, and the second terminal of the first capacitor C1 is grounded. The first capacitor C1 and the second resistor R2 are connected in parallel. When the control module 13 sets pin GPIO1 of the switching chip U1 to a high level, the NO pin and COM pin (GND) of the switching chip U1 are connected, and the filter module 11 discharges. The charging and discharging time of the capacitor can be determined by the time constant. During discharge, During charging, When the voltage changes to 63.2% of the total change, the corresponding time is 1. When the voltage changes to 95.0% of the total change, the corresponding time is 3. .

[0034] As an example, if the normal value of the ADC (analog-to-digital converter) (the conversion result within each cycle's ADC sampling window) is 600 when the sensor is within the marked distance range, the sensor outputs a high level. When the EFT test is performed, the accumulated charge on the ADC exceeds the threshold of 600, reaching a maximum of approximately 1000. When the ADC value is greater than 600 + hysteresis (100), the sensor outputs a low level; when the ADC value is less than or equal to 600, it outputs a high level, causing the sensor to trigger falsely. In this embodiment of the invention, the third resistor R3 is 200Ω, the first capacitor C1 is 10nF, and the 95% discharge time is 3... =6 The second resistor R2 is 4.7KΩ, the first capacitor C1 is 10nF, and the charging time to 95% is 3... =141 The minimum cycle length of the sensor is 6. +141 + , For the sampling time, if the sampling time is 10... The minimum length of a period is 157. In practice, the second preset duration can be three times the discharge time constant plus a preset third duration. For example, if the preset third duration is 494... The minimum period of the sensor is 651. After EFT testing, the ADC waveform was obtained. A schematic diagram of the ADC waveform is shown below. Figure 3 As shown, Figure 3 The vertical axis represents the ADC value, and the horizontal axis represents the sampling point (e.g., 1 represents the first sampling point). The maximum ADC value is approximately 640 < 640 + 100 (hysteresis value), therefore, the sensor is less prone to false triggering. Simultaneously, the minimum period of the sensor is 651... The sensor outputs according to the minimum duration of the cycle, which has little impact on the switching frequency.

[0035] In some embodiments, the analog switch module 12 further includes a fourth resistor, the first end of which is connected to the switch chip, and the second end of which is connected to the power supply voltage.

[0036] In one specific embodiment, such as Figure 2 As shown, the analog switch module 12 also includes a seventh resistor R116, an eighth resistor R5, and a third capacitor C3. The seventh resistor R116 is connected to the second end of the fourth resistor. The seventh resistor R116 is connected in series with the eighth resistor R5. The eighth resistor R5 is connected in series with the third capacitor C3. One end of the third capacitor C3 is grounded.

[0037] In some embodiments, the filtering module 11 further includes a first resistor, the first end of which is connected to the first end of the first capacitor.

[0038] In some embodiments, the control module 13 includes a main control chip connected to the analog switch module 12 to control the analog switch module 12 to disconnect within a first preset time period and to control the analog switch module 12 to turn on within a second preset time period.

[0039] In one specific embodiment, the circuit schematic of the control module 13 is as follows: Figure 4 As shown, the control module 13 includes a main control chip U8, which is connected to the switch chip of the analog switch module 12 through the GPIO1 pin.

[0040] The electrical fast transient / burst filter circuit provided in this embodiment of the invention includes a control module that controls the analog switch module to disconnect for a first preset duration and to turn on for a second preset duration. The first preset duration is determined based on a second resistor and a first capacitor in the filter module, and the second preset duration is determined based on a third resistor and a first capacitor in the analog switch module. The filter module receives interference signals and charges when the analog switch module is disconnected and discharges when the analog switch module is turned on. By precisely coordinating the on / off timing of the analog switch module through the control module, the filter module effectively controls the switching on / off timing of the analog switch module. The alternating process of charging to absorb EFT pulse energy during the on-time period and discharging interference charge during the on-time period suppresses signal abrupt changes at the ADC sampling end from the source. Unlike software filtering, which requires a large number of redundant samples to smooth interference, the above technical solution can completely filter out interference signals and reduce the impact on the switching frequency. Furthermore, the above technical solution abandons the traditional complex filter circuit and can effectively suppress EFT pulse groups using only a simple network composed of a filter module, an analog switch module, and a control module. Since it does not need to deal with electromagnetic interference across the entire frequency band, the device parameters can be optimized and reduced, greatly reducing the PCB area occupied and solving the problem of limited space on high-density circuit boards.

[0041] This invention provides an inductor sensor circuit, the schematic diagram of which is shown below. Figure 5 As shown, the inductor sensor circuit 100 includes the electrical fast transient burst filter circuit 10 and the oscillation circuit 20 described in the above embodiment. The oscillation circuit 20 is used to transmit oscillation signals.

[0042] In some embodiments, the oscillation circuit 20 includes a first transistor, a second transistor, and a second capacitor. The first terminal of the first transistor is grounded, the second terminal of the first transistor is connected to the power supply voltage, the third terminal of the first transistor is connected to the third terminal of the second transistor, the second terminal of the second transistor is connected to the first terminal of the second transistor through the second capacitor, and the first terminal of the second transistor is also connected to the first terminal of the first capacitor.

[0043] In one specific embodiment, the oscillation circuit 20 is used to send an oscillation signal for detection. During the EFT test, interference signals enter the inductive sensor circuit from the power supply voltage, and then enter the electrical fast transient / burst filter circuit. The circuit schematic of the oscillation circuit 20 is shown below. Figure 6 As shown, the first terminal of the first transistor is grounded, the second terminal of the first transistor is connected to the power supply voltage through the ninth resistor R27, and the first terminal of the second transistor is also connected to the first terminal of the first capacitor C1.

[0044] In some embodiments, the inductive sensor circuit further includes a signal distance adjustment circuit, which includes a variable resistor, a fifth resistor, and a sixth resistor. The first terminal of the variable resistor is connected to the first terminal of the second transistor through the sixth resistor, the second terminal of the variable resistor is grounded, and the variable resistor and the fifth resistor are connected in parallel.

[0045] In one specific embodiment, the distance of the oscillation signal is adjusted by changing the value of the variable resistor in the signal distance adjustment circuit, thereby adjusting the detection distance of the sensor. The schematic diagram of the signal distance adjustment circuit is shown below. Figure 7 As shown, the signal distance adjustment circuit further includes a tenth resistor R15, an eleventh resistor R93, a twelfth resistor R97, a thirteenth resistor R111, a fourteenth resistor R113, and a fourth capacitor C12. The first terminal of the variable resistor is connected to the first terminal of the second transistor through a sixth resistor R16 and a tenth resistor R15.

[0046] In some embodiments, the inductor sensor circuit further includes a dual series small-signal switching diode, the first end of which is connected to the first end of the second transistor, the second end of which is connected to the first end of the variable resistor, and the third end of which is connected to the first end of the first capacitor.

[0047] In one specific embodiment, the circuit schematic of the dual series small-signal switching diodes is as follows: Figure 8 As shown, the first, second, and third terminals of the dual series small-signal switching diodes are connected to the oscillation circuit 20, the signal distance adjustment circuit, and the electrical fast transient / burst filter circuit, respectively.

[0048] This invention provides a method for filtering electrically fast transient bursts, the flowchart of which is shown below. Figure 9 As shown, the electrical fast transient burst filtering method includes: S101, the analog switch module is disconnected within a first preset time period, wherein the first preset time period is determined based on the second resistor and the first capacitor in the filter module; S102, the filtering module receives the interference signal and is charged when the analog switch module is disconnected; S103, control the analog switch module to conduct within a second preset time period, wherein the second preset time period is determined based on the third resistor of the analog switch module and the first capacitor in the filter module; S104, causing the filter module to discharge when the analog switch module is turned on.

[0049] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0050] The above embodiments merely illustrate preferred implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention should be determined by the appended claims.

Claims

1. An electrical fast transient / burst filter circuit, characterized in that, It includes a filtering module, an analog switch module, and a control module; The control module is used to control the analog switch module to disconnect within a first preset time period and to control the analog switch module to conduct within a second preset time period. The first preset time period is determined based on the second resistor and the first capacitor in the filter module, and the second preset time period is determined based on the third resistor in the analog switch module and the first capacitor in the filter module. The filtering module is used to receive interference signals, charge when the analog switch module is off, and discharge when the analog switch module is on.

2. The electrical fast transient / burst filter circuit according to claim 1, characterized in that, The analog switch module also includes a switch chip, which is connected to the first terminal of the first capacitor through the third resistor. The second terminal of the first capacitor is grounded, and the first capacitor is connected in parallel with the second resistor. The first capacitor is charged when the analog switch module is off and discharged when the analog switch module is on.

3. The electrical fast transient / burst filter circuit according to claim 2, characterized in that, The analog switch module also includes a fourth resistor, the first end of which is connected to the switch chip, and the second end of which is connected to the power supply voltage.

4. The electrical fast transient / burst filter circuit according to claim 1, characterized in that, The filtering module further includes a first resistor, the first end of which is connected to the first end of the first capacitor.

5. The electrical fast transient / burst filter circuit according to claim 1, characterized in that, The control The control module includes a main control chip, which is connected to the analog switch module to control the analog switch module to disconnect within a first preset time period and to control the analog switch module to turn on within a second preset time period.

6. An inductive sensor circuit, characterized in that, The invention includes the electrical fast transient burst filter circuit and the oscillation circuit as described in any one of claims 1 to 5, wherein the oscillation circuit is used to transmit an oscillation signal.

7. The inductive sensor circuit according to claim 6, characterized in that, The oscillation circuit includes a first transistor, a second transistor, and a second capacitor. The first terminal of the first transistor is grounded, the second terminal of the first transistor is connected to the power supply voltage, the third terminal of the first transistor is connected to the third terminal of the second transistor, the second terminal of the second transistor is connected to the first terminal of the second transistor through the second capacitor, and the first terminal of the second transistor is also connected to the first terminal of the first capacitor.

8. The inductive sensor circuit according to claim 7, characterized in that, The inductive sensor circuit also includes a signal distance adjustment circuit, which includes a variable resistor, a fifth resistor, and a sixth resistor. The first end of the variable resistor is connected to the first end of the second transistor through the sixth resistor, the second end of the variable resistor is grounded, and the variable resistor and the fifth resistor are connected in parallel.

9. The inductive sensor circuit according to claim 8, characterized in that, The inductor sensor circuit also includes a dual series small-signal switching diode, the first end of which is connected to the first end of the second transistor, the second end of which is connected to the first end of the variable resistor, and the third end of which is connected to the first end of the first capacitor.

10. A method for filtering electrically fast transient pulse groups, characterized in that, include: The control analog switch module is disconnected within a first preset time period, wherein the first preset time period is determined based on the second resistor and the first capacitor in the filter module; The filtering module receives interference signals and is charged when the analog switch module is disconnected. The control analog switch module is turned on within a second preset time period, wherein the second preset time period is determined based on the third resistor of the analog switch module and the first capacitor in the filter module; The filter module discharges when the analog switch module is turned on.

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