Water immersion detection rod circuit based on H-bridge direct current commutation

Abstract

The invention discloses a water immersion detection rod circuit based on H-bridge direct current commutation, and relates to the technical field of water immersion detection, and the circuit mainly comprises a water immersion induction unit which is used for supplying power to a plurality of water immersion electrodes arranged along a detection cavity; the main control chip is used for generating a switching signal for periodically switching the current direction and a selection signal for selecting a target electrode, and identifying the water immersion height according to a detection signal; the H-bridge unit is used for periodically switching the direction of the direct current supplied to the water immersion sensing unit according to the switching signal; the multiplexing unit is used for gating the target electrode and the bottom electrode to form a detection loop according to a selection signal; and the water immersion signal detection unit outputs high and low level detection signals to the main control chip according to the loop conduction state. According to the scheme, electrode corrosion is delayed through current commutation, and multi-stage water level detection is achieved through the multiplexing technology. Electrolytic corrosion is delayed by periodically switching the power supply current direction of the water immersion detection electrode, and the service life of the electrode is prolonged.

Description

Technical Field

[0001] This invention relates to the field of water immersion detection technology, and more specifically to a water immersion detection rod circuit based on H-bridge DC commutation. Background Technology

[0002] Water immersion detection technology is widely used in waterproofing monitoring of basements, data centers, warehouses, factories, and other locations. Its core principle lies in determining water level by analyzing changes in the electrical signal generated when electrodes contact water. Traditional water immersion detection schemes often use either DC unidirectional power supply or AC excitation to drive the detection electrodes. While DC unidirectional detection is simple and low-cost, prolonged power supply can lead to electrolytic corrosion of the electrodes due to electrochemical reactions, especially when the water contains ions, which accelerates the corrosion process and severely impacts electrode lifespan and detection reliability. AC excitation, while mitigating electrode polarization and corrosion, often results in more complex circuit structures requiring additional AC signal generation and processing circuits. This increases system cost and power consumption and may introduce interference, affecting detection accuracy and stability. Furthermore, existing technologies often employ multiple independent detection circuits or relay arrays to achieve multi-level water level detection, resulting in large circuit sizes, complex wiring, reduced reliability, and difficulty in achieving multi-channel intelligent switching and signal acquisition within limited space. Therefore, how to effectively suppress electrode corrosion and extend sensor life in water immersion detection systems while maintaining a simple system structure, controllable cost, and support for reliable multi-level water level detection has become a pressing technical problem in this field. Summary of the Invention

[0003] To effectively suppress electrode corrosion and extend sensor life in a water immersion detection system while maintaining a simple system structure, controllable cost, and support for reliable multi-level water level detection, this invention proposes a water immersion detection rod circuit based on H-bridge DC commutation. The water immersion detection rod internally includes a water immersion detection cavity and a waterproof circuit cavity. The water immersion detection rod circuit is placed within the waterproof circuit cavity. The water immersion detection rod circuit includes: The water immersion sensing unit is used to connect a direct current and power two or more water immersion electrodes arranged along the extension direction of the water immersion detection cavity in the water immersion detection cavity. The main control chip is used to send switching signals for periodic switching control of conduction direction, as well as selection signals for selecting the target water immersion electrode for conduction state detection. It is also used to receive detection signals and identify the corresponding water immersion height. The H-bridge unit is used to connect to an external DC power supply and provide DC current to the water immersion sensing unit. It also periodically switches the conduction direction of the DC current in the water immersion sensing unit through the internal H-bridge circuit according to the switching signal. The multiplexing unit is used to select the target water immersion electrode and the water immersion detection rod bottom water immersion electrode according to the selection signal, and to detect the conduction status under the corresponding electrode settings according to the current DC current conduction direction of the H-bridge unit. The water immersion signal detection unit is used to output a high-level detection signal to the main control chip when the target water immersion electrode is on, and output a low-level detection signal to the main control chip when it is not on, based on the conduction status of each target water immersion electrode.

[0004] This invention uses an H-bridge unit to periodically commutate the power supply current to the detection electrodes, effectively suppressing electrode electrolytic corrosion and significantly extending service life. At the same time, it utilizes a multiplexing unit to achieve intelligent selection and signal acquisition of multiple electrodes by a single detection circuit. While ensuring multi-level water level detection functionality, it greatly simplifies the system structure, reduces cost and power consumption, and improves the long-term reliability and economy of water immersion detection.

[0005] Furthermore, the water immersion sensing unit is a connector, which includes symmetrical pairs of connectors on both sides and electrically connected in pairs inside. One end of the connector pair is used to connect to a direct current, and the other end is used to connect to each water immersion electrode arranged along the extension direction of the water immersion detection cavity and installed in the water immersion detection cavity in sequence.

[0006] Furthermore, the H-bridge unit is a DRV8210PDSGR chip, containing pins one through nine, wherein: The first pin is connected to an external DC power supply through the twelfth resistor; The second and third pins are DC current power supply pins, and their electrode directions are opposite. The third pin is connected to the DC current power supply terminal of the connector at the bottom of the water immersion detection rod where the water immersion electrode is located. Pin 4 and pin 9 are grounded; Pins 7 and 8 are connected in parallel to an external DC power supply and grounded through capacitor 15. Pins 5 and 6 are signal receiving pins used to receive switching signals.

[0007] Furthermore, the multiplexing chip is a 74HC4051D chip, containing pins one through sixteen, wherein: The first, second, fourth, fifth, and twelfth to fifteenth pins are conduction state detection pins, which are individually connected to the DC current power supply terminals of the connectors of each water immersion electrode except for the water immersion electrode at the bottom of the water immersion detection rod. Pins 6 through 8 are grounded; Pins 9 to 11 are signal receiving pins, used to receive selection signals; The third pin is connected to the second pin in the H-bridge unit DRV8210PDSGR chip; Pin 16 is connected to an external DC power supply and grounded through capacitor 16.

[0008] Furthermore, the selection signal is a high-low level signal, and the power supply control of the eight conduction state detection pins is achieved through eight combinations of high-low level signals from three pins.

[0009] Furthermore, the water immersion signal detection unit includes a first field-effect transistor, wherein: The gate of the first field-effect transistor is connected to the first pin in the H-bridge unit DRV8210PDSGR chip; The source of the first field-effect transistor is connected to an external DC power supply and grounded through the fourteenth capacitor; The drain of the first field-effect transistor is grounded through the eleventh resistor and the detection signal is output through the tenth resistor.

[0010] Furthermore, the water immersion electrodes are arranged at a preset spacing along the extension direction of the water immersion detection cavity.

[0011] Furthermore, in the water immersion sensing unit, each water immersion electrode includes a first port and a second port, wherein the first port is used to connect to a DC current power supply, and the second port is exposed in the water immersion detection cavity.

[0012] Compared with the prior art, the present invention has at least the following beneficial effects: (1) The water immersion detection rod circuit based on H-bridge DC commutation proposed in this invention realizes the periodic switching of the DC current direction of the water immersion detection electrode by introducing the H-bridge DC commutation unit, thereby effectively balancing the electrochemical polarization of the electrode under water immersion state, significantly slowing down the electrolytic corrosion rate of the electrode, and extending the service life and reliability of the detection rod. (2) The multiplexer unit is combined to intelligently select multiple water immersion electrodes arranged along the extension direction of the detection cavity. The identification of water immersion states at different heights can be achieved through a single detection circuit. Under the premise of ensuring multi-level water level detection function, the circuit structure is greatly simplified, the system cost and power consumption are reduced, and the occupation of external microcontroller pin resources is reduced. (3) Through the cooperation of the water immersion signal detection unit and the main control chip, the conduction status signal of each electrode is output in real time and accurately, which facilitates the rapid judgment and response of water level height. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the overall circuit of a water immersion detection rod circuit based on H-bridge DC commutation; Figure 2 This is a schematic diagram of the internal circuitry of the H-bridge unit chip. Detailed Implementation

[0014] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of protection of the present invention.

[0015] This invention provides a water immersion detection rod circuit based on H-bridge DC commutation. Its core concept lies in creatively applying H-bridge commutation technology, used for DC motor drives, to the field of water immersion detection. By periodically switching the direction of the DC current applied to the detection electrodes, electrode corrosion caused by electrochemical electrolysis is effectively suppressed, thereby extending the service life of the detection rod. Simultaneously, it integrates intelligent multiplexing technology, using a single detection circuit to cyclically select multiple water immersion electrodes arranged vertically, achieving graded identification of water level height. While ensuring reliability, this greatly simplifies the system structure and reduces cost and power consumption.

[0016] The basic carrier of this water immersion detection system is a water immersion detection rod, the rod body of which is typically made of insulating and corrosion-resistant materials (such as PVC or ABS engineering plastics). The rod body is axially divided into two main chambers: a water immersion detection chamber and a waterproof circuit chamber. The water immersion detection chamber is a slender tubular structure with holes or slits in its sidewalls or ends to allow liquid entry. Within this chamber, multiple water immersion electrodes are installed at predetermined intervals along its extension direction (i.e., the direction of expected water level change, typically vertical). These electrodes are preferably made of corrosion-resistant conductive materials, such as stainless steel, with one end (first port) connected to the circuit via a wire, and the other end (second port) exposed in the internal space of the water immersion detection chamber for contact with any potential liquid intrusion. The bottom electrode is typically designated as the common electrode or reference electrode. All electrical connections to the electrodes are led out to the waterproof circuit chamber via sealed connectors, ensuring the detection chamber's airtightness. The waterproof circuit chamber is a completely sealed compartment for housing and protecting the water immersion detection circuit board of this invention from moisture or immersion.

[0017] like Figure 1 As shown, the core control component of the water immersion detection circuit is a main control chip, such as a microcontroller (MCU). The main control chip is responsible for system logic control and signal processing. It mainly generates two types of control signals: one is a switching signal used to control the periodic switching of the DC current direction; the other is a selection signal used to select which specific water immersion electrode is connected to the detection loop. Simultaneously, the main control chip is also responsible for receiving and processing the level signals from subsequent water immersion signal detection units, determining which electrodes are in the conducting state, and thus resolving the current water immersion height information. The main control chip is connected to other functional units of the system through its general-purpose input / output pins.

[0018] To achieve automatic commutation of DC current direction, this embodiment introduces an H-bridge unit. This unit preferably uses an integrated H-bridge driver chip, such as the DRV8210PDSGR device. Figure 1 and Figure 2 As shown, this chip integrates a complete H-bridge power circuit as well as necessary control logic and protection circuitry. The chip contains pins one through nine, and their connections and functions are specifically configured as follows: The chip's first pin is connected to an external DC power supply (e.g., 3.3V, labeled D3V3) via a twelfth resistor (R12). This pin actually connects to an internal high-side transistor driver circuit. The second and third pins are the two output pins of the H-bridge, used to provide DC current to the immersion sensing unit, and their output polarities are opposite. In specific applications, the third pin is fixedly connected to the power supply terminal (COM) of the immersion electrode at the bottom of the immersion detection lever, which serves as the common electrode. The fourth and ninth pins are connected together to system ground. The seventh and eighth pins are connected in parallel to an external DC power supply and simultaneously grounded through a fifteenth capacitor (C15), which acts as a power supply decoupling and filtering capacitor. The fifth and sixth pins are the chip's signal receiving pins, labeled IN1 / PH and IN2 / EN respectively, and they are directly connected to the two corresponding control pins of the main control chip.

[0019] The main control chip precisely controls the on / off state of the four switching transistors inside the H-bridge by sending specific high-low level combination logic signals (i.e., switching signals) to these two control pins, thereby causing the direction of the current output from the second and third pins to periodically reverse. For example, during a certain period, the current flows out from the second pin and back to the third pin through the external circuit; during the next period, the control current flows out from the third pin and back to the second pin through the external circuit. This periodic reversal operation causes the polarity of the voltage applied to the immersion electrode to change alternately, thereby balancing the electrochemical reaction and effectively delaying electrode corrosion.

[0020] In this embodiment, the water immersion sensing unit is specifically embodied as a multi-pin connector, such as a 6-pin connector with a 1.27mm pitch. Figure 1 (See page 8). This connector contains multiple pairs of symmetrically arranged, internally electrically connected pins. One end of each pin pair (e.g., the pin on one side of the circuit board) is used to receive direct current, the source of which varies depending on the connected electrodes: In this embodiment, for the common water immersion electrode at the bottom of the water immersion detection rod, its connector pair is directly connected to DC current from the output pin of the H-bridge unit; while for the target water immersion electrodes at other heights on the rod, their respective connector pairs are connected to DC current from the corresponding channel of the multiplexing unit. The other end of the connector pair (e.g., connected to the inside of the detection rod via a cable) is used to connect to the corresponding physical water immersion electrode. These connectors provide a modular and maintainable connection method for the system, facilitating the separation and assembly of the detection rod and the circuit board.

[0021] To detect the status of multiple water-immersed electrodes with minimal circuit resources, this invention employs a multiplexing unit. This unit preferably uses a multiplexed analog switch chip, such as the 8-channel analog multiplexer / demultiplexer of model 74HC4051D. Figure 1 (P9). This chip has sixteen pins, and in this embodiment, their connection relationship is as follows: The chip's eight pins—Y4 (first pin), Y6 (second pin), Y7 (third pin), Y5 (fifth pin), Y3 (twelfth pin), Y0 (thirteenth pin), Y1 (fourteenth pin), and Y2 (fifteenth pin)—are defined as conduction state detection pins. They are individually connected to the DC current supply terminal of the connector pair corresponding to each water immersion electrode (excluding the bottom common electrode). For example, in connector P8, electrodes WATER1 to WATER5, corresponding to water levels from low to high, are connected to five of these pins, with the remaining pins left floating or reserved. The chip's sixth, seventh, and eighth pins, as well as pin 7 (VEE), which serves as the analog signal reference ground, are all connected to system ground. The chip's ninth (S0), tenth (S1), and eleventh (S2) pins are address selection pins, connected as signal receiving pins to the three corresponding control pins of the main control chip to receive selection signals from the main control chip. The selection signal is essentially a combination of 3-bit binary encoded high and low level signals. By changing the voltage levels (000 to 111) on pins S2, S1, and S0, one of the eight channels can be intelligently selected and connected internally to the common terminal (pin 3, marked Z). Pin 16 (VCC) of the chip is connected to an external DC power supply (e.g., 3.3V) and grounded through a capacitor 16 (C16) to stabilize its operating voltage. Crucially, the common terminal (pin 3, Z) of this multiplexing chip is not directly grounded or connected to a fixed potential, but is connected to pin 2 of the H-bridge unit DRV8210PDSGR chip. This connection is key to the formation of the entire detection loop.

[0022] The water immersion signal detection unit converts the conduction state of the water immersion electrode into a digital level signal recognizable by the main control chip. The core of this unit can be an electronic switching circuit composed of field-effect transistors (FETs). In a specific example, a P-channel enhancement-mode FET (e.g., AON7421, labeled Q1) is used. The gate of this first FET is connected to the first pin of the H-bridge unit DRV8210PDSGR chip. Its source is connected to an external DC power supply and grounded through a fourteenth capacitor (C14). Its drain is connected to ground through an eleventh resistor (R11), and also led out through a tenth resistor (R10). This lead-out point is the system's water immersion detection signal output terminal, which is sent to an input pin of the main control chip that has interrupt or polling functionality.

[0023] The working principle of the circuit in this water immersion signal detection unit is as follows: When the H-bridge driver chip is working, the voltage state of its first pin changes with the output state of the bridge circuit. When no water immersion electrode is short-circuited by water, the channel selected by the multiplexer is open-circuited with the bottom common electrode, the entire detection loop is closed, and the first pin of the H-bridge driver chip is in a voltage state that cuts off the first field-effect transistor (Q1), causing its drain to be pulled down to a low level by the eleventh resistor (R11), thereby outputting a low-level detection signal. When a selected water immersion electrode is immersed in water, the electrode forms a conductive path between the water and the bottom common electrode. At this time, a complete current loop powered by the H-bridge is established: the current flows out from the second pin (or the third pin, depending on the current DC current direction) of the H-bridge, through the common terminal of the multiplexer, the selected channel, the corresponding water immersion electrode, the water, the bottom common electrode, and back to the third pin (or the second pin) of the H-bridge. The flow of this current will generate a voltage drop in the internal and external paths of the H-bridge driver chip, causing a voltage jump at its first pin. This jump is sufficient to make the gate-source voltage of the first field-effect transistor (Q1) reach the turn-on threshold, thus turning on the first field-effect transistor (Q1). Once the first field-effect transistor (Q1) is turned on, its drain voltage will be quickly pulled up to near the source voltage (i.e., the external power supply voltage), thereby outputting a high-level detection signal to the main control chip through the tenth resistor (R10).

[0024] The entire system operates as follows: After power-on initialization, the main control chip first sets the H-bridge output DC current in an initial direction via the IN1 and IN2 pins on the H-bridge driver chip. Next, the main control chip controls the multiplexer via the S2, S1, and S0 address lines of the analog switch chip, sequentially selecting each water-immersed electrode channel starting from the electrode with the lowest water level (e.g., the channel corresponding to WATER1). After selecting each channel, the main control chip delays for a short period to allow the circuit to stabilize, then reads the detection signal output by the water immersion signal detection unit. If the read signal is low, it indicates that the currently selected electrode is not submerged and the loop is not connected. If the read signal is high, it indicates that the currently selected electrode has contacted the water and formed a path with the bottom common electrode. The main control chip records the electrode positions corresponding to all high-level output signals, with the highest position indicating the current water immersion height. After completing one scan of all electrodes, the main control chip commands the H-bridge unit to switch the direction of the output DC current by changing the IN1 and IN2 signals. After the current direction is switched, another complete electrode scan is performed. This cycle repeats, with the current direction alternating at a certain period (e.g., once per second or once per minute, adjustable as needed). This ensures that each submerged electrode is exposed to approximately equal amounts of positive and negative voltage polarity, achieving an anti-electrolytic corrosion effect. The main control chip can report the identified water level information to a host computer or monitoring center via a communication interface (such as UART or I2C), or it can directly control the alarm device.

[0025] In summary, the water immersion detection rod circuit based on H-bridge DC commutation proposed in this invention fundamentally reduces electrode corrosion problems through H-bridge DC periodic commutation technology. Furthermore, through multiplexing technology, multi-level water level detection is achieved with a minimalist circuit, saving MCU pins and PCB space. Ultimately, the entire system is compact, low-cost, and highly reliable, making it very suitable for large-scale deployment and application in various situations requiring long-term stable monitoring.

[0026] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indication will also change accordingly.

[0027] Furthermore, in this invention, descriptions involving terms such as "first," "second," and "a" are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0028] In this invention, unless otherwise explicitly specified and limited, the terms "connection," "fixed," etc., should be interpreted broadly. For example, "fixed" can mean a fixed connection, a detachable connection, or an integral part; it can mean a mechanical connection or an electrical connection; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0029] Furthermore, the technical solutions of the various embodiments of the present invention can be combined with each other, but only if they are feasible for those skilled in the art. If the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

Claims

1. A water immersion detection rod circuit based on H-bridge direct current commutation, the water immersion detection rod comprising a water immersion detection cavity and a waterproof circuit cavity inside, the water immersion detection rod circuit is placed in the waterproof circuit cavity, characterized in that, The water immersion detection rod circuit comprises: a water immersion sensing unit for connecting a direct current and supplying power to two or more water immersion electrodes arranged along the extension direction of the water immersion detection cavity; a main control chip for sending a switching signal for conducting direction periodic switching control and a selection signal for selecting a target water immersion electrode for conducting state detection, and receiving a detection signal and identifying the corresponding water immersion height; an H-bridge unit for connecting an external direct current power supply and providing a direct current for the water immersion sensing unit, and periodically switching the conducting direction of the direct current in the water immersion sensing unit through the internal H-bridge circuit according to the switching signal; a multiplexing unit for selecting a target water immersion electrode and a water immersion electrode at the bottom of the water immersion detection rod body according to the selection signal, and conducting state detection under the corresponding electrode setting according to the direct current conducting direction of the current H-bridge unit; a water immersion signal detection unit for outputting a high-level detection signal to the main control chip when the target water immersion electrode is conducting, and outputting a low-level detection signal to the main control chip when the target water immersion electrode is not conducting.

2. The water immersion detection rod circuit based on H-bridge commutation of claim 1, wherein, The water immersion sensing unit is a connector, which comprises a pair of connector ports symmetrically arranged on both sides and electrically connected to each other, one end of the connector port is used for connecting a direct current, and the other end of the connector port is used for sequentially connecting each water immersion electrode arranged along the extension direction of the water immersion detection cavity and installed in the water immersion detection cavity.

3. The water immersion detection rod circuit based on H-bridge commutation of claim 2, wherein, The H-bridge unit is a DRV8210PDSGR chip, which comprises a first pin to a ninth pin, wherein: the first pin is connected to an external direct current power supply through a twelfth resistor; the second pin and the third pin are direct current power supply pins, and the electrode directions of the two pins are opposite, wherein the third pin is connected to the direct current power supply end of the connector port pair where the water immersion electrode at the bottom of the water immersion detection rod body is located; the fourth pin and the ninth pin are grounded; the seventh pin and the eighth pin are connected in parallel to an external direct current power supply and grounded through a fifteenth capacitor; the fifth pin and the sixth pin are signal receiving pins for receiving a switching signal.

4. The water immersion detection rod circuit based on H-bridge commutation of claim 3, wherein, The multiplexing chip is a 74HC4051D chip, which comprises a first pin to a sixteenth pin, wherein: the first pin, the second pin, the fourth pin, the fifth pin, and the twelfth pin to the fifteenth pin are conducting state detection pins, which are respectively connected to the direct current power supply end of the connector port pair where each water immersion electrode except the water immersion electrode at the bottom of the water immersion detection rod body is located; the sixth pin to the eighth pin are grounded; the ninth pin to the eleventh pin are signal receiving pins for receiving a selection signal; the third pin is connected to the second pin in the H-bridge unit DRV8210PDSGR chip; the sixteenth pin is connected to an external direct current power supply and grounded through a sixteenth capacitor.

5. The water immersion detection rod circuit based on H-bridge commutation of claim 4, wherein, The selection signal is a high-low level signal, and the power supply control of the eight conducting state detection pins is realized through three pins and eight high-low level signal combinations.

6. The water immersion detection rod circuit based on H-bridge commutation of claim 3, wherein, The water immersion signal detection unit comprises a first field effect transistor, wherein: the gate of the first field effect transistor is connected to the first pin in the H-bridge unit DRV8210PDSGR chip; the source of the first field effect transistor is connected to an external direct current power supply and grounded through a fourteenth capacitor; The drain of the first field effect tube is grounded through an eleventh resistor and outputs a detection signal through a tenth resistor.

7. The water immersion detection rod circuit based on H-bridge commutation of claim 1, wherein, The water immersion electrodes are arranged at a preset interval along the extension direction of the water immersion detection cavity.

8. The water immersion detection rod circuit based on H-bridge commutation of claim 1, wherein, In the water immersion sensing unit, each water immersion electrode includes a first port and a second port, wherein the first port is used for connecting direct current power supply, and the second port is exposed in the water immersion detection cavity.

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