An air energy water heater leakage protection circuit

Abstract

The utility model discloses an air energy water heater electric leakage protection circuit, including the water heater power cord, electric leakage mutual inductor, signal processing module and electric leakage protection module that connect gradually, electric leakage mutual inductor is used for inductive water heater whether the electric leakage current of existence, and will electric leakage current transmission to signal processing circuit, signal processing module is used for to electric leakage current processing, and judge electric leakage current whether greater than preset value, electric leakage protection module is used for after receiving signal processing module output electric leakage signal executes alarm feedback and power -off operation, when signal processing module judges electric leakage mutual inductor input electric leakage current greater than preset value, makes electric leakage protection module executes alarm feedback and power -off operation, thereby realizes to the effective monitoring and interception of water heater electric leakage, the utility model has the characteristics of high detection precision, circuit overall stable.

Description

Technical Field

[0001] This utility model relates to the technical field of household appliances, and in particular to a leakage protection circuit for an air source water heater. Background Technology

[0002] If an electric water heater leaks electricity during use, the hot water from the shower will become electrified. Due to the humid environment, it is difficult for the user to leave the danger zone quickly, ultimately leading to electric shock, which is extremely dangerous. To prevent this, electric water heaters for showers are generally equipped with a residual current device (RCD). When a leakage occurs, the RCD trips, cutting off the main power supply and ensuring personal safety.

[0003] Currently, leakage current transformers used in air source heat pump equipment have limitations in detection accuracy and a narrow range of applicable environments. Some leakage current transformers exhibit significantly increased detection errors in environments with large temperature variations, affecting the accurate judgment of leakage. At the same time, the output voltage stability of some products is insufficient, fluctuating greatly under different load conditions, making it difficult to meet the requirements for accurate detection. Furthermore, some products only use a single threshold to judge leakage and have not optimized the protection logic for the high-frequency start-stop characteristics of water heaters, resulting in a high probability of false tripping or leakage tripping.

[0004] Therefore, based on the above-mentioned technical problems, this application proposes a leakage protection circuit for air source water heaters with high detection accuracy and overall circuit stability. Utility Model Content

[0005] The purpose of this invention is to overcome the shortcomings of the existing technology and provide a leakage protection circuit for air source water heaters with high detection accuracy and stable overall circuit.

[0006] To achieve the above objectives, this utility model provides a leakage protection circuit for an air source water heater, comprising a water heater power cord, a leakage current transformer, a signal processing module, and a leakage protection module connected in sequence. The leakage current transformer senses the presence of leakage current in the water heater and transmits the leakage current to the signal processing circuit. The signal processing module processes the leakage current and determines whether the leakage current exceeds a preset value. The leakage protection module performs alarm feedback and power-off operations after receiving the leakage signal output by the signal processing module. When the signal processing module determines that the leakage current input to the leakage current transformer exceeds the preset value, it causes the leakage protection module to perform alarm feedback and power-off operations, thereby achieving effective monitoring and interception of water heater leakage.

[0007] Furthermore, the preferred transformation ratio of the leakage current transformer is 2000:1.

[0008] Furthermore, the signal processing module includes a voltage offset circuit, an operational amplifier circuit, and an active filter and comparator circuit.

[0009] Furthermore, the voltage offset circuit includes an operational amplifier U7B, resistors R35 and R36, and a capacitor C29 for filtering. The operational amplifier U7B is used to generate a voltage offset signal. Resistor R35 works in conjunction with resistor R36 to set the voltage offset amplitude. The two ends of resistor R36 are connected to the operating power supply and the non-inverting input terminal VIN+ of operational amplifier U7B, respectively. One end of resistor R35 is connected to resistor R36, and the other end is connected to the non-inverting input terminal VIN+ of operational amplifier U7B via capacitor C29. The input terminal of operational amplifier U7B inputs an offset voltage to the non-inverting input terminal VIN+ of operational amplifier IC1A via resistor R2.

[0010] Furthermore, the operational amplifier circuit includes connector CN6, operational amplifier IC1A, resistors R1, R2, R12, R18, and sampling resistor R15. Operational amplifier IC1A amplifies the signal input to connector CN6. Sampling resistor R15 detects the leakage current on the water heater power line. Port 1 of connector CN6 is connected to resistor R18 and then to the non-inverting input VIN+ of operational amplifier IC1A. Port 2 of connector CN6 is connected to resistor R1 and then to the inverting input VIN- of operational amplifier IC1A. Sampling resistor R15 is connected in parallel between ports 1 and 2 of connector CN6 and then grounded. The non-inverting input VIN+ of operational amplifier IC1A is connected to the output via resistor R12.

[0011] Furthermore, the leakage current detection range of the sampling resistor R15 is 10-30mA, and the operational amplifier IC1A preferably has an operational amplifier gain of 20 times.

[0012] Furthermore, the active filtering and comparator circuit includes an operational amplifier IC1B, capacitors C10 and C11, resistors R13, R16, R17, and R21. The operational amplifier IC1B is used to further amplify the signal output by the operational amplifier IC1A. The capacitors C10 and C11 are used to cooperate with the operational amplifier IC1B to achieve active filtering. The two ends of the resistor R13 are connected to the operating power supply and the inverting input terminal VIN of the operational amplifier IC1B, respectively. The two ends of the resistor R16 are connected to ground and the inverting input terminal VIN- of the operational amplifier IC1B, respectively. The output terminal of the operational amplifier IC1B outputs a low-level LP signal to the leakage protection module through the resistor R17. The two ends of the resistor R21 are connected to the output terminal of the operational amplifier IC1A and the non-inverting input terminal VIN- of the operational amplifier IC1B, respectively. The two ends of the capacitor C10 are connected to ground and the 8-port of the operational amplifier IC1B, respectively. The two ends of the capacitor C11 are connected to the resistor R17.

[0013] The present invention adopts the above-described solution, and its beneficial effects are as follows: Precise leakage protection: The leakage current transformer adopts a 2000:1 transformation ratio, which converts 10-30mA leakage current into 5-15μA output current, thereby matching the detection range of subsequent circuits and improving detection sensitivity.

[0014] Improved anti-interference capability: High-frequency noise is filtered out through active filtering and comparison circuits, reducing false alarms caused by electromagnetic interference from the water heater and improving overall anti-interference capability. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the water heater leakage protection circuit in this embodiment.

[0016] Figure 2 This is a circuit diagram of the water heater leakage protection circuit in this embodiment. Detailed Implementation

[0017] To facilitate understanding of this utility model, a more complete description of it is provided below with reference to the accompanying drawings. The drawings illustrate preferred embodiments of the utility model. However, this utility model can be implemented in many different forms and is not limited to the embodiments described herein. These embodiments are provided to provide a more thorough and complete understanding of the disclosure of this utility model.

[0018] See appendix Figure 1 , 2As shown in this embodiment, an air source water heater leakage protection circuit includes a water heater power cord, a leakage current transformer, a signal processing module, and a leakage protection module connected in sequence. The leakage current transformer is used to sense whether there is leakage current in the water heater and transmit the leakage current to the signal processing circuit. The signal processing module is used to process the leakage current and determine whether the leakage current is greater than a preset value (preferably 10mA). The leakage protection module is used to perform alarm feedback and power-off operation after receiving the leakage signal output by the signal processing module. The signal processing module includes a voltage offset circuit, an operational amplifier circuit, and an active filter and comparison circuit. When the signal processing module determines that the leakage current input by the leakage current transformer is greater than the preset value (10mA), it causes the leakage protection module to perform alarm feedback and power-off operation, thereby realizing effective monitoring and interception of water heater leakage.

[0019] See appendix Figure 2 As shown, in this embodiment, the voltage offset circuit includes an operational amplifier U7B, resistors R35 and R36, and a capacitor C29 for filtering. The operational amplifier U7B generates a voltage offset signal. Resistor R35 works in conjunction with resistor R36 to set the voltage offset amplitude. The two ends of resistor R36 are connected to the operating power supply and the non-inverting input terminal VIN+ of operational amplifier U7B, respectively. One end of resistor R35 is connected to resistor R36, and the other end is connected to the non-inverting input terminal VIN+ of operational amplifier U7B via capacitor C29. The input terminal of operational amplifier U7B inputs an offset voltage to the non-inverting input terminal VIN+ of operational amplifier IC1A via resistor R2. After the leakage current input from the leakage current transformer is converted into a voltage signal by sampling resistor R15, the voltage offset circuit adjusts the level of the voltage signal to ensure that the voltage signal can be adapted to the input range of subsequent circuits, thereby improving the accuracy of judging the leakage phenomenon of the water heater.

[0020] See appendix Figure 2As shown, in this embodiment, the operational amplifier circuit includes connector CN6, operational amplifier IC1A, resistors R1, R2, R12, R18, and sampling resistor R15. Operational amplifier IC1A amplifies the signal input to connector CN6. Sampling resistor R15 detects the leakage current on the water heater power line (the detected leakage current can be converted into a corresponding voltage signal). Port 1 of connector CN6, after connecting resistor R18, is connected to the non-inverting input terminal VIN+ of operational amplifier IC1A. Port 2 of connector CN6, after connecting resistor R1, is connected to the operational amplifier... The inverting input terminal VIN- of the IC1A is connected in phase. A sampling resistor R15 is connected in parallel between ports 1 and 2 of connector CN6 and then grounded. The non-inverting input terminal VIN+ of the operational amplifier IC1A is connected to the output terminal via resistor R12. The voltage signal (converted from leakage current) input to the voltage offset circuit is amplified by the operational amplifier circuit, realizing lossless transmission of the voltage signal and improving the accuracy of judgment. Furthermore, the high input impedance and low output impedance characteristics of the operational amplifier circuit isolate the preceding and following circuits, protecting the safety of subsequent circuits and avoiding the phenomenon of misjudging leakage current, thus improving the stability of the overall circuit.

[0021] Furthermore, the leakage current detection range of the sampling resistor R15 is 10-30mA (i.e., the output voltage range of the operational amplifier at this location is 2.6-2.8V), which converts the leakage current in the range of 10mA-30mA into an output current of 5μA-15μA, thereby matching the detection range of the subsequent circuit and improving the detection sensitivity of leakage phenomena in the power cord of the water heater; and the operational amplifier IC1A at this location is preferably 20 times amplification factor.

[0022] See appendix Figure 2 As shown, in this embodiment, the active filtering and comparator circuit includes an operational amplifier IC1B, capacitors C10 and C11, resistors R13, R16, R17, and R21. The operational amplifier IC1B is used to further amplify the signal output by the operational amplifier IC1A. Capacitors C10 and C11 are used to cooperate with the operational amplifier IC1B to achieve active filtering. The two ends of resistor R13 are connected to the operating power supply and the inverting input terminal VIN of the operational amplifier IC1B, respectively. The two ends of resistor R16 are connected to ground and the inverting input terminal VIN- of the operational amplifier IC1B, respectively. The output terminal of the operational amplifier IC1B outputs a low-level LP signal to the leakage protection module through resistor R17. The two ends of resistor R21 are connected to the output terminal of the operational amplifier IC1A and the non-inverting input terminal VIN- of the operational amplifier IC1B, respectively. The two ends of capacitor C10 are connected to ground and the 8-port of the operational amplifier IC1B, respectively. The two ends of capacitor C11 are connected to resistor R17.

[0023] By filtering out high-frequency noise through an active filter circuit, false alarms caused by electromagnetic interference from the water heater can be reduced, and the anti-interference capability can be improved. Secondly, the comparison circuit can accurately compare the voltage signal (converted from leakage current) processed by the active filter circuit with the preset value (10mA), thereby achieving effective monitoring of water heater leakage.

[0024] Based on the above circuit composition, a leakage protection circuit for an air source water heater is formed. For ease of understanding, the working principle will be further explained below with reference to specific embodiments.

[0025] Because the leakage current detection range of the leakage protection circuit in this embodiment is 10-30mA (i.e., the operational amplifier output voltage range is 2.6-2.8V), the trigger threshold of the leakage protection module's protection mechanism is set to 2.5V (which can be set within the safe operating range according to actual conditions). By setting an active filter and comparator circuit to filter out high-frequency noise, false alarms caused by electromagnetic interference from the water heater are reduced, and the detection accuracy is improved. By using the sampling resistor R15 in conjunction with the specific operational amplifier amplification factor in the operational amplifier circuit, the relevant signals are ensured to be within the effective range of the analog-to-digital converter, so that the output voltage and leakage current have a linear relationship, which facilitates the leakage protection module to quickly identify the leakage signal and trigger protection.

[0026] When the leakage current transformer detects no leakage in the water heater power line, the active filtering and comparison circuit outputs a low-level signal LP to the leakage protection module. Thus, the user can use the water heater normally under safe conditions without triggering the protection mechanism of the leakage protection module. When the leakage current transformer detects a leakage in the water heater's power line (leakage current reaching 10mA), it causes the leakage current to undergo a ratio conversion through the leakage current transformer and is conducted to the sampling resistor R15 (converting it into a voltage signal). After amplification by the operational amplifier circuit, filtering by the active filter and comparator circuit, and comparison with a threshold, it is determined that the voltage value on the sampling resistor R15 exceeds the threshold. This causes the active filter and comparator circuit to immediately output a high-level signal to the leakage protection module, thereby triggering the protection mechanism of the leakage protection module to issue an alarm feedback to the user (an external buzzer or alarm light can be connected here to remind the user). This achieves effective monitoring of the water heater leakage in this embodiment. Secondly, it causes the operational amplifier IC1B to flip, stopping the water heater from running, thus realizing the power-off protection function of the water heater. This relatively avoids the leakage current being conducted to the user during the use of the water heater, reducing the probability of leakage accidents and improving the safety of using the water heater.

[0027] The embodiments described above are merely preferred embodiments of this utility model and are not intended to limit the utility model in any way. Any modifications or alterations made by those skilled in the art to the technical solution of this utility model without departing from its scope are equivalent embodiments of this utility model. Therefore, all equivalent changes made based on the concept of this utility model without departing from its scope should be covered within the protection scope of this utility model.

Claims

1. A leakage protection circuit for an air source water heater, characterized in that: The system includes a water heater power cord, a leakage current transformer, a signal processing module, and a leakage current protection module connected in sequence. The leakage current transformer senses the presence of leakage current in the water heater and transmits the leakage current to the signal processing circuit. The signal processing module processes the leakage current and determines whether the leakage current exceeds a preset value. The leakage current protection module performs alarm feedback and power-off operations after receiving the leakage signal output by the signal processing module. When the signal processing module determines that the leakage current input to the leakage current transformer exceeds the preset value, it causes the leakage current protection module to perform alarm feedback and power-off operations, thereby achieving effective monitoring and interception of water heater leakage.

2. The leakage protection circuit for an air source water heater according to claim 1, characterized in that: The ratio of the leakage current transformer is converted to 2000:

1.

3. The leakage protection circuit for an air source water heater according to claim 1, characterized in that: The signal processing module includes a voltage offset circuit, an operational amplifier circuit, and an active filter and comparator circuit.

4. The leakage protection circuit for an air source water heater according to claim 3, characterized in that: The voltage offset circuit includes an operational amplifier U7B, resistors R35 and R36, and a capacitor C29 for filtering. The operational amplifier U7B generates a voltage offset signal. Resistor R35 works in conjunction with resistor R36 to set the voltage offset amplitude. The two ends of resistor R36 are connected to the operating power supply and the non-inverting input terminal VIN+ of operational amplifier U7B, respectively. One end of resistor R35 is connected to resistor R36, and the other end is connected to the non-inverting input terminal VIN+ of operational amplifier U7B via capacitor C29. The input terminal of operational amplifier U7B inputs an offset voltage to the non-inverting input terminal VIN+ of operational amplifier IC1A via resistor R2.

5. The leakage protection circuit for an air source water heater according to claim 3, characterized in that: The operational amplifier circuit includes connector CN6, operational amplifier IC1A, resistors R1, R2, R12, R18, and sampling resistor R15. Operational amplifier IC1A amplifies the signal input to connector CN6. Sampling resistor R15 detects the leakage current on the water heater power line. Port 1 of connector CN6 is connected to resistor R18 and then to the non-inverting input VIN+ of operational amplifier IC1A. Port 2 of connector CN6 is connected to resistor R1 and then to the inverting input VIN- of operational amplifier IC1A. Sampling resistor R15 is connected in parallel between ports 1 and 2 of connector CN6 and then grounded. The non-inverting input VIN+ of operational amplifier IC1A is connected to the output via resistor R12.

6. The leakage protection circuit for an air source water heater according to claim 5, characterized in that: The leakage current detection range of the sampling resistor R15 is 10-30mA, and the operational amplifier IC1A has an operational amplifier gain of 20 times.

7. The leakage protection circuit for an air source water heater according to claim 3, characterized in that: The active filtering and comparator circuit includes an operational amplifier IC1B, capacitors C10 and C11, resistors R13, R16, R17, and R21. The operational amplifier IC1B is used to further amplify the signal output by the operational amplifier IC1A. Capacitors C10 and C11 work together with the operational amplifier IC1B to achieve active filtering. The two ends of resistor R13 are connected to the operating power supply and the inverting input terminal VIN of the operational amplifier IC1B, respectively. The two ends of resistor R16 are connected to ground and the inverting input terminal VIN- of the operational amplifier IC1B, respectively. The output terminal of the operational amplifier IC1B outputs a low-level LP signal to the leakage protection module through resistor R17. The two ends of resistor R21 are connected to the output terminal of the operational amplifier IC1A and the non-inverting input terminal VIN- of the operational amplifier IC1B, respectively. The two ends of capacitor C10 are connected to ground and the 8-port of the operational amplifier IC1B, respectively. The two ends of capacitor C11 are connected to resistor R17.

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