Null line and live line reverse connection detection circuit and electric water heater

Abstract

The utility model discloses a null line and live line reverse connection detection circuit and an electric water heater, the null line and live line reverse connection detection circuit comprises a detection branch circuit, a feedback branch circuit and a control unit, the detection branch circuit is provided with a live line connection end and a null line connection end, and the detection branch circuit comprises a one-way conduction unit and a current limiting unit; the one-way conduction unit and the current limiting unit are connected in series between the live wire connecting end and the zero line connecting end, the one-way conduction unit is configured to only allow current to flow from the zero line connecting end to the live wire connecting end, the input end of the feedback branch is connected between the one-way conduction unit and the zero line connecting end, and the output end of the feedback branch is connected with a detection port of the control unit. According to the utility model, whether the live wire and the zero wire are reversely connected can be detected, the safety can be improved, and the heating rate can be improved.

Description

Technical Field

[0001] This utility model relates to abnormal detection circuit technology, and in particular to a neutral and live wire reverse connection detection circuit and an electric water heater. Background Technology

[0002] When installing an electric water heater, the live wire should first be connected in series with the water heater switch (i.e., the water heater switch is installed on the live wire), then the water heater itself should be connected in series, and finally the wire should be returned to the neutral wire. This way, when the user turns off the water heater switch, the water heater will not be energized, which is beneficial for the safe maintenance of the water heater.

[0003] If the neutral and live wires of an electric water heater are reversed, the water heater will still be connected to the live wire even after the user turns off the water heater switch. In other words, the water heater will still be energized. If the user or maintenance personnel directly touch the water heater at this time, there is a safety risk. Utility Model Content

[0004] One of the technical problems solved by this utility model is to provide a neutral and live wire reverse connection detection circuit, which can detect whether the live wire and neutral wire of the electric water heater are reversed, thus improving safety.

[0005] The second technical problem solved by this utility model is to provide an electric water heater that can detect whether the live wire and neutral wire are reversed, thereby improving safety.

[0006] The first technical problem mentioned above is solved by the following technical solution:

[0007] A reverse connection detection circuit for live and neutral wires includes a detection branch, a feedback branch, and a control unit;

[0008] The detection branch has a live wire connection terminal and a neutral wire connection terminal. The detection branch includes a unidirectional conduction unit and a current limiting unit, which are connected in series between the live wire connection terminal and the neutral wire connection terminal.

[0009] The input end of the feedback branch is connected between the unidirectional conduction unit and the neutral wire connection end, and the output end of the feedback branch is connected to the detection port of the control unit.

[0010] The unidirectional conduction unit is configured to allow current to flow only from the neutral wire connection terminal to the live wire connection terminal.

[0011] The neutral and live wire reverse connection detection circuit provided by this utility model can be used in electric water heaters. When the live wire and neutral wire of the electric water heater are reversed, the detection branch is turned on, and there is a current from the neutral wire connection end to the live wire connection end. After the feedback branch detects the current, it outputs a feedback signal and sends the feedback signal to the control unit for subsequent reminders. This helps to improve safety, and the circuit is simple and low in cost.

[0012] In some embodiments of this invention, the unidirectional conduction unit includes at least one unidirectional diode.

[0013] In some embodiments of this invention, the current limiting unit includes a current limiting resistor.

[0014] In some embodiments of this utility model, the feedback branch includes a sampling resistor, which is connected in series in the detection branch, and one end of the sampling resistor near the neutral wire connection terminal is connected to the detection port of the control unit.

[0015] In some embodiments of this utility model, the feedback branch includes a relay switch, the control coil of the relay switch is connected in series in the detection branch, and the contacts of the relay switch are connected to the detection port of the control unit.

[0016] The second technical problem mentioned above is solved by the following technical solution:

[0017] An electric water heater, comprising:

[0018] An air switch, wherein the air switch is connected to a neutral wire, a live wire, and a ground wire;

[0019] The motherboard is provided with at least two contactors and a reverse connection detection circuit for live and neutral wires as provided in the foregoing embodiment. The live wire connection terminal is used to connect to the live wire, and the neutral wire connection terminal is used to connect to the neutral wire.

[0020] There are at least two heating elements, one end of which is connected to the live wire via a corresponding contactor, and the other end of which is connected to the neutral wire; and the total power of the at least two heating elements is greater than 3300W.

[0021] The electric water heater provided by this utility model, when the live wire and neutral wire of the water heater are reversed, detects the continuity of the detection branch, indicating the presence of current flowing from the neutral wire connection end to the live wire connection end. The feedback branch detects this current and outputs a feedback signal, which is then sent to the control unit for subsequent alerts, thus improving safety. Furthermore, at least two heating elements have a total power greater than 3300W, and the heating elements are connected to an air switch, allowing multiple heating elements to heat simultaneously, thereby increasing the heating rate.

[0022] In some embodiments of this utility model, the electric water heater further includes a shell and an inner tank located inside the shell, at least two heating tubes are located inside the inner tank, the main board is located between the shell and the inner tank, and the air switch is located outside the shell.

[0023] In some embodiments of this utility model, the electric water heater further includes an inner liner, which is located between the outer shell and the inner tank. The inner liner has an electrical compartment, and the main board is located in the electrical compartment.

[0024] In some embodiments of this utility model, the electric water heater further includes an over-temperature protector, which is connected in series between the air switch and the main board.

[0025] In some embodiments of this utility model, the electric water heater further includes a leakage current induction coil, which is connected to the main board and is used to detect the leakage current of the live wire or the neutral wire. Attached Figure Description

[0026] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments.

[0027] Figure 1 A schematic diagram of the structure of a neutral / live wire reverse connection detection circuit provided by this utility model;

[0028] Figure 2 A circuit diagram of a neutral / live wire reverse connection detection circuit provided by this utility model;

[0029] Figure 3 A circuit diagram of a neutral / live wire reverse connection detection circuit provided by this utility model;

[0030] Figure 4 This utility model provides a structural schematic diagram of an electric water heater;

[0031] Figure 5 An internal circuit diagram of an electric water heater provided by this utility model.

[0032] In the picture:

[0033] 100. Reverse polarity detection circuit; 110. Detection branch; 120. Feedback branch; 130. Control unit; 111. One-way conduction unit; 112. Current limiting unit; 121. Relay switch; 210. Main board; 220. Outer shell; 230. Inner liner; 240. Lining; 241. Electrical compartment. Detailed Implementation

[0034] To make the technical problems solved by this utility model, the technical solutions adopted, and the technical effects achieved clearer, the technical solutions of the embodiments of this utility model will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0035] In the description of this utility model, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0036] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature. Additionally, the terms "first" and "second" are used merely for descriptive distinction and have no specific meaning.

[0037] Figure 1 This is a schematic diagram of the structure of a neutral / live wire reverse connection detection circuit provided by this utility model, as shown below. Figure 1 As shown, the neutral-live wire reverse connection detection circuit includes a detection branch 110, a feedback branch 120, and a control unit 130.

[0038] The detection branch 110 has a live wire connection terminal LP and a neutral wire connection terminal NP. The detection branch 110 includes a unidirectional conduction unit 111 and a current limiting unit 112, which are connected in series between the live wire connection terminal LP and the neutral wire connection terminal NP. The unidirectional conduction unit 111 is configured to allow current to flow only from the neutral wire connection terminal NP to the live wire connection terminal LP. The current limiting unit 112 limits the current in the detection branch 110, preventing the risk of damage to the unidirectional conduction unit 111 due to excessive current in the detection branch 110.

[0039] The input terminal of the feedback branch 120 is connected between the unidirectional conduction unit 111 and the neutral connection terminal NP, and the output terminal of the feedback branch 120 is connected to the detection port DT of the control unit 130.

[0040] The control unit 130 can be a single-chip microcomputer, microcontroller, etc., and this utility model does not limit it.

[0041] For example, the live wire connection terminal LP is connected to the live wire of the electric water heater, and the neutral wire connection terminal NP is connected to the neutral wire of the electric water heater. When the live wire and neutral wire of the electric water heater are normally connected (i.e., the live wire of the electric water heater is connected to the live wire of the power transmission line, and the neutral wire of the water heater is connected to the neutral wire of the power transmission line), since the unidirectional conduction unit 111 does not allow current to flow from the live wire connection terminal LP to the neutral wire connection terminal NP, that is, there is no current in the detection branch 110, the feedback branch 120 has no feedback signal output, and the control unit 130 determines that the live wire and neutral wire of the electric water heater are normally connected. When the live wire and neutral wire of the electric water heater are reversed (i.e., the live wire of the electric water heater is connected to the neutral wire of the power line, and the neutral wire of the water heater is connected to the live wire of the power line), since the unidirectional conduction unit 111 allows current to flow from the neutral wire connection terminal NP to the live wire connection terminal LP, that is, the detection branch 110 is conducting, and there is current from the neutral wire connection terminal NP to the live wire connection terminal LP. After the feedback branch 120 detects this current, it outputs a feedback signal. When the control unit 130 receives the feedback signal, it determines that the live wire and neutral wire of the electric water heater are reversed. The control unit 130 can issue a reverse connection warning signal, such as an alarm in the form of sound or light.

[0042] This utility model provides a reverse connection detection circuit for live and neutral wires, including a detection branch, a feedback branch, and a control unit. The detection branch has a live wire connection terminal and a neutral wire connection terminal, and includes a unidirectional conduction unit and a current limiting unit connected in series between the live wire connection terminal and the neutral wire connection terminal. The unidirectional conduction unit is configured to allow current to flow only from the neutral wire connection terminal to the live wire connection terminal. The input terminal of the feedback branch is connected between the unidirectional conduction unit and the neutral wire connection terminal, and the output terminal of the feedback branch is connected to the detection port of the control unit. When the live and neutral wires of the electric water heater are reversed, the detection branch conducts, and there is current flowing from the neutral wire connection terminal to the live wire connection terminal. After detecting this current, the feedback branch outputs a feedback signal. When the control unit receives the feedback signal, it determines that the live and neutral wires of the electric water heater are reversed and issues a reverse connection warning signal, thus improving safety.

[0043] Figure 2 This invention provides a circuit diagram of a neutral-live wire reverse connection detection circuit. Based on the aforementioned embodiments, this embodiment further describes in detail the detection branch and feedback branch of this invention.

[0044] In some embodiments of this utility model, the unidirectional conduction unit includes at least one unidirectional diode. The position of the unidirectional diode in the detection branch is not limited, as long as it enables current to flow only from the neutral wire connection terminal to the live wire connection terminal. For example, Figure 2As shown, in this embodiment, the unidirectional conduction unit 111 includes two unidirectional diodes, namely unidirectional diode D1 and unidirectional diode D2. The anode of unidirectional diode D1 is connected to the neutral wire connection terminal NP, the cathode of unidirectional diode D1 is connected to the first terminal of the current limiting unit 112, the second terminal of the current limiting unit 112 is connected to the anode of unidirectional diode D2, and the cathode of unidirectional diode D2 is connected to the live wire connection terminal LP.

[0045] In some embodiments of this utility model, such as Figure 2 As shown, the current limiting unit 112 includes a current limiting resistor R1. The first end of the current limiting resistor R1 is connected to the cathode of the unidirectional diode D1, and the second end of the current limiting resistor R1 is connected to the input terminal of the feedback branch 120. It should be noted that in other embodiments of this invention, the current limiting unit 112 may also include multiple resistors connected in series, as long as the purpose of current limiting can be achieved; this invention does not impose any limitations on this.

[0046] In some embodiments of this utility model, the feedback branch 120 includes a sampling resistor R2, which is connected in series in the detection branch 110. The end of the sampling resistor R2 closest to the neutral wire connection terminal NP is connected to the detection port DT of the control unit 130. For example, the first end of the sampling resistor R2 is connected to the second end of the current-limiting resistor R1, and the second end of the sampling resistor R2 is connected to the anode of the unidirectional diode D2. For example, when the live wire L and neutral wire N of the electric water heater are reversed, since the unidirectional conduction unit 111 allows current to flow from the neutral wire connection terminal NP to the live wire connection terminal LP, i.e., the detection branch 110 is conducting, there is a current from the neutral wire connection terminal NP to the live wire connection terminal LP. The feedback signal output by the feedback branch 120 is the voltage of the sampling resistor R2. When the control unit 130 receives the feedback signal, it determines that the live wire L and neutral wire N of the electric water heater are reversed and issues a reverse connection warning signal.

[0047] Figure 3 This invention provides a circuit diagram of a neutral-live wire reverse connection detection circuit. Based on the aforementioned embodiments, this embodiment describes another implementation scheme for the feedback branch.

[0048] like Figure 3As shown, the feedback branch 120 includes a relay switch 121. The control coil L1 of the relay switch 121 is connected in series in the detection branch 110. For example, the first end of the control coil L1 is connected to the second end of the current-limiting resistor R1, and the first end of the control coil L1 is connected to the anode of the unidirectional diode D2. One end of the contact C1 of the relay switch 121 is connected to the detection port DT of the control unit 130, and the other end of the contact C1 is connected to the reference voltage source Vf. For example, when the live wire L and the neutral wire N of the electric water heater are reversed, since the unidirectional conduction unit 111 allows current to flow from the neutral wire connection terminal NP to the live wire connection terminal LP, that is, the detection branch 110 is turned on, there is a current from the neutral wire connection terminal NP to the live wire connection terminal LP, the control coil L1 of the relay switch 121 is energized, the contact C1 is closed, the feedback branch 120 is turned on, and a feedback signal is generated. When the control unit 130 receives the feedback signal, it determines that the live wire L and the neutral wire N of the electric water heater are reversed and issues a reverse connection warning signal.

[0049] The specific circuit of the detection branch in this embodiment is the same as that in the previous embodiment, and will not be described again here.

[0050] It should be noted that in other embodiments of this utility model, the feedback branch can also be implemented in other ways, such as optocouplers, as long as it can enable the phase control unit to send a feedback signal when the live wire and neutral wire of the electric water heater are reversed. This utility model does not limit this.

[0051] This utility model also provides an electric water heater. Figure 4 This is a structural schematic diagram of an electric water heater provided by this utility model. Figure 5 An internal circuit diagram of an electric water heater provided by this utility model, such as... Figure 4 , 5 As shown, the electric water heater includes:

[0052] An air circuit breaker (CB) is connected to a neutral wire (N), a live wire (L), and a ground wire (E). The live wire (L) connects to the live wire of the power transmission line, the neutral wire (N) connects to the neutral wire of the power transmission line, and the ground wire (E) is used for grounding. The air circuit breaker (CB) provides overload and short-circuit protection. When the current in the circuit exceeds the rated value, the air circuit breaker (CB) will detect the overload and automatically trip to prevent overheating of wires or damage to equipment.

[0053] The mainboard 210 is equipped with at least two contactors K (also known as relay switches) and a reverse connection detection circuit 100 for neutral and live wires as provided in any of the foregoing embodiments of this utility model. The live wire connection terminal LP is used to connect to the live wire L, and the neutral wire connection terminal NP is used to connect to the neutral wire N. The structure and principle of the reverse connection detection circuit 100 for neutral and live wires have been described in detail in the foregoing embodiments, and will not be repeated here.

[0054] There are at least two heating elements HT, one end of which is connected to the live wire L via a corresponding contactor K, and the other end is connected to the neutral wire N; and the total power of the at least two heating elements HT is greater than 3300W. For example, such as... Figure 5 As shown, the mainboard 210 has three contactors K, and the electric water heater includes three heating elements HT. One end of each heating element HT is connected to the live wire L through a corresponding contactor K, and the other end of the heating element HT is connected to the neutral wire N. Exemplarily, each heating element HT can be controlled to heat individually, or two of them can be heated together, or all three can be heated together; this utility model does not impose any limitations on this.

[0055] In some embodiments of this utility model, such as Figure 4 As shown, the electric water heater also includes a housing 220 and an inner tank 230 located inside the housing 220. Exemplarily, the housing 220 and the inner tank 230 are insulated from each other. At least two heating elements HT are located inside the inner tank 230, a main board 210 is located in the gap between the housing 220 and the inner tank 230, and an air switch CB is located outside the housing 220. The inner tank 230 is used to store water, and the heating elements HT are used to heat the water in the inner tank 230. The inner tank 230 is provided with an inlet pipe 231 and an outlet pipe 232. One end of the inlet pipe 231 extends into the inner tank 230 to the top of the inner tank 230, and the other end extends to the outside of the housing 220, forming an inlet end. One end of the outlet pipe 232 extends into the inner tank 230 to the bottom of the inner tank 230, and the other end extends to the outside of the housing 220, forming an outlet end.

[0056] In some embodiments of this utility model, such as Figure 4 As shown, the inner liner 230 also contains an anode rod 233, which (usually made of magnesium or an aluminum-magnesium alloy) protects the inner liner 230 by sacrificing itself. Because the anode rod 233 is more reactive than the metal in the inner liner 230 (such as iron), it preferentially reacts with corrosive ions in the water, thus preventing corrosion of the inner liner 230. This protective mechanism is based on electrochemical principles; the anode rod 233 acts as a sacrificial anode, attracting corrosion current and preventing damage to the inner liner 230.

[0057] In some embodiments of this utility model, such as Figure 4 As shown, the electric water heater also includes an inner liner 240, which is located between the outer shell 220 and the inner tank 230. The inner liner 240 can be made of foam, sponge, etc., and serves to fix the inner tank 230, provide cushioning, and maintain heat. The inner liner 240 has an electrical compartment 241, and the main board 210 is located inside the electrical compartment 241.

[0058] In some embodiments of this utility model, such as Figure 5As shown, the electric water heater also includes an over-temperature protector (TCO), which is connected in series between the air switch CB and the main board 210. The TCO uses a built-in temperature sensor to monitor the temperature changes in the circuit in real time, and automatically cuts off the power supply when the temperature exceeds a set threshold to prevent the circuit from overheating or being damaged.

[0059] In some embodiments of this utility model, such as Figure 5 As shown, the electric water heater also includes a leakage current induction coil (LIC), which is connected to the main board 210. The leakage current induction coil (LIC) is used to detect leakage current in the live wire or neutral wire. The working principle of the leakage current induction coil is based on the principle of a zero-sequence current transformer. When the circuit is working normally, the three-phase currents are balanced, and the vector sum of the currents in the zero-sequence current transformer is zero, so no induced voltage or current is generated. When leakage or electric shock occurs, the current balance in the circuit is disrupted, generating a zero-sequence current. This current induces magnetic flux in the iron core of the zero-sequence current transformer, thereby generating an induced current in the secondary coil. The control unit determines that leakage has occurred in the circuit based on this induced current.

[0060] In some embodiments of this utility model, such as Figure 4 , 5 As shown, the electric water heater also includes a first temperature sensor TS1 and a second temperature sensor TS2. The first temperature sensor TS1 and the second temperature sensor TS2 are located inside the inner tank 230 and are used to monitor the water temperature in different areas. Both the first temperature sensor TS1 and the second temperature sensor TS2 are connected to the control unit on the main board 210. The control unit controls the operating state of the heating element based on the detected water temperature. For example, when the first temperature sensor TS1 detects that the water temperature is lower than the set temperature, the control unit controls the contactor corresponding to the heating element closest to the first temperature sensor TS1 to close, and that heating element begins heating.

[0061] In some embodiments of this utility model, such as Figure 4 , 5 As shown, the electric water heater also includes a control panel CP, which is located on the outside of the housing 220. The control panel CP provides a human-machine interface, and users can use the control panel CP to set the water temperature, control the contactor K to turn on and off, and view the internal water temperature, etc. This utility model is not limited here.

[0062] In the description herein, it should be understood that the terms "upper," "lower," "left," "right," etc., are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of description and simplification of operation, 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, and therefore should not be construed as a limitation of this utility model.

[0063] In the description of this specification, references to terms such as "an embodiment," "example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example.

[0064] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style of the specification is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

[0065] The technical principles of this utility model have been described above with reference to specific embodiments. These descriptions are merely for explaining the principles of this utility model and should not be construed as limiting the scope of protection of this utility model in any way. Based on this explanation, those skilled in the art can readily conceive of other specific embodiments of this utility model without any inventive effort, and these embodiments will all fall within the scope of protection of this utility model.

Claims

1. A circuit for detecting reverse connection of live and neutral wires, characterized in that, It includes a detection branch (110), a feedback branch (120), and a control unit (130); The detection branch (110) has a live wire connection terminal and a neutral wire connection terminal. The detection branch (110) includes a unidirectional conduction unit (111) and a current limiting unit (112). The unidirectional conduction unit (111) and the current limiting unit (112) are connected in series between the live wire connection terminal and the neutral wire connection terminal. The input end of the feedback branch (120) is connected between the unidirectional conduction unit (111) and the neutral wire connection end, and the output end of the feedback branch (120) is connected to the detection port of the control unit (130). The unidirectional conduction unit (111) is configured to allow current to flow only from the neutral wire connection to the live wire connection.

2. The neutral / live wire reverse connection detection circuit according to claim 1, characterized in that, The unidirectional conduction unit (111) includes at least one unidirectional diode.

3. The neutral / live wire reverse connection detection circuit according to claim 1, characterized in that, The current limiting unit (112) includes a current limiting resistor.

4. The neutral / live wire reverse connection detection circuit according to claim 1, characterized in that, The feedback branch (120) includes a sampling resistor connected in series in the detection branch (110), and one end of the sampling resistor near the neutral wire connection terminal is connected to the detection port of the control unit (130).

5. The neutral / live wire reverse connection detection circuit according to claim 1, characterized in that, The feedback branch (120) includes a relay switch (121), the control coil of which is connected in series in the detection branch (110), and the contacts of which are connected to the detection port of the control unit (130).

6. An electric water heater, characterized in that, include: An air switch, wherein the air switch is connected to a neutral wire, a live wire, and a ground wire; The motherboard (210) is provided with at least two contactors and a neutral-live wire reverse connection detection circuit (100) as described in any one of claims 1-5, wherein the live wire connection terminal is used to connect to the live wire and the neutral wire connection terminal is used to connect to the neutral wire. There are at least two heating elements, one end of which is connected to the live wire via a corresponding contactor, and the other end of which is connected to the neutral wire; and the total power of the at least two heating elements is greater than 3300W.

7. The electric water heater according to claim 6, characterized in that, It also includes an outer shell (220) and an inner liner (230) located inside the outer shell (220), at least two of the heating tubes are located inside the inner liner (230), the main board (210) is located between the outer shell (220) and the inner liner (230), and the air switch is located outside the outer shell (220).

8. The electric water heater according to claim 7, characterized in that, It also includes an inner liner (240) located between the outer shell (220) and the inner liner (230), the inner liner (240) having an electrical compartment (241), and the main board (210) located inside the electrical compartment (241).

9. The electric water heater according to claim 6, characterized in that, It also includes an over-temperature protector, which is connected in series between the air switch and the main board (210).

10. The electric water heater according to claim 6, characterized in that, It also includes a leakage current induction coil, which is connected to the main board (210) and is used to detect the leakage current of the live wire or the neutral wire.

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