Circuit board of household heating device and household heating device

Abstract

A detection circuit for a household heating device and the household heating device. The detection circuit includes a mains voltage detection unit, which includes a rectifier circuit, a current limiting circuit, a photoelectric coupler, a sampling circuit, and a filter circuit. Mains power is input into the mains detection unit through a mains input terminal. The rectifier circuit and the current limiting circuit are located between the mains input terminal and the photoelectric coupler. The sampling circuit and the filter circuit are located downstream of the photoelectric coupler. A detection voltage is output through a voltage detection terminal connected to the filter circuit. The circuit is simple, low-cost, and compact. The photoelectric coupler is used to separate strong and weak electricity, thereby avoiding the risk of high-voltage electric shock during voltage detection.

Description

Technical Field

[0001] The invention relates to a household heating device and a circuit board thereof. Background Art

[0002] Household appliances are heated by inputting AC power. To better control the heating temperature, the impact of AC voltage fluctuations must be considered. Existing technologies use transformers for voltage detection, but these are large, making the product bulky. There are also solutions that directly use resistors to divide the voltage, but this can easily cause electric shock to users. Summary of the Invention

[0003] The object of the present invention is to provide a detection circuit and a household heating device with a simple structure and the ability to avoid electric shock.

[0004] To achieve the above-mentioned purpose, the present invention adopts the following technical solution: a detection circuit for a household appliance, the detection circuit including a mains voltage detection unit, the mains voltage detection unit including a rectifier circuit, a current limiting circuit, a photoelectric coupler, a sampling circuit and a filter circuit, the mains power is input into the mains voltage detection unit through a mains input terminal, the rectifier circuit and the current limiting circuit are located between the mains input terminal and the photoelectric coupler, the sampling circuit and the filter circuit are located downstream of the photoelectric coupler, and a detection voltage is output through the voltage detection terminal connected to the filter circuit.

[0005] The present invention also discloses a household heating device, a household heating device, including a circuit board, the circuit board having the detection circuit described above, the household heating device including a toilet heater, an instant hot water dispenser, a portable water dispenser, and an instant hot constant temperature faucet, the household heating device can be powered by AC power input, an electrical switch device is provided between the AC power input end and the power device of the household heating device, an MCU is integrated in the circuit board, and the MCU sends a power control signal according to the detection voltage to control the on and off of the electrical switch.

[0006] The detection circuit of the household heating device of the present application utilizes a rectifier circuit, a current limiting circuit, a photoelectric coupler, a current limiting circuit, a sampling circuit and a filter circuit. The input mains power is electrically connected to the optocoupler isolation circuit through the rectifier circuit and the current limiting circuit. The voltage detection end is located downstream of the optocoupler isolation circuit, and the detection voltage is output through the voltage detection end to realize the detection of the mains voltage. The circuit is simple, low in cost, and compact in size. In addition, the photoelectric coupler can be used to separate strong and weak electricity, avoiding the risk of high-voltage electric shock when detecting voltage. In addition, the control of the connection between the household heating device and the input mains power can be adjusted by changes in the voltage of the mains power, which is conducive to ensuring the power of the heating device, that is, ensuring the stability of the heating device in providing the required temperature. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 It is the first system connection diagram of household heating equipment;

[0008] Figure 2 It is the second system connection diagram of household heating equipment;

[0009] Figure 3 yes Figure 1 Schematic diagram of the detection circuit;

[0010] Figure 4 yes Figure 2 Schematic diagram of the detection circuit;

[0011] Figure 5 This is a circuit connection diagram of a first embodiment of a detection circuit;

[0012] Figure 6 1 is a circuit connection diagram of a second embodiment of the detection circuit;

[0013] Figure 7 1 is a circuit connection diagram of a third embodiment of the detection circuit;

[0014] Figure 8 1 is a circuit connection diagram of a fourth embodiment of the detection circuit;

[0015] Figure 9 1 is a circuit connection diagram of a fifth embodiment of the detection circuit;

[0016] Figure 10 1 is a circuit connection diagram of a sixth embodiment of the detection circuit;

[0017] Figure 11 1 is a circuit connection diagram of a seventh embodiment of the detection circuit;

[0018] Figure 12 1 is a circuit connection diagram of an eighth embodiment of the detection circuit;

[0019] Figure 13 1 is a circuit connection diagram of a ninth embodiment of the detection circuit;

[0020] Figure 14 10. A circuit connection diagram of a detection circuit according to a tenth embodiment;

[0021] Figure 15 It is a schematic diagram of the mains voltage waveform;

[0022] Figure 16 This is a schematic diagram of the voltage waveform of the detection circuit after passing through the diode rectifier circuit;

[0023] Figure 17This is a schematic diagram of the voltage waveform of the detection circuit after passing through the rectifier bridge circuit;

[0024] Figure 18 It is a schematic diagram of the voltage waveform at the voltage detection end. DETAILED DESCRIPTION

[0025] The present invention will be further described below with reference to the accompanying drawings and specific embodiments:

[0026] With the development of smart home appliances, they are approaching intelligent control. Home heating appliances are an important part of home appliances. Home heating appliances can be toilet heaters, instant hot water dispensers, portable water dispensers, and instant hot thermostatic faucets. The intelligent control of home heating appliances is mainly temperature control. Home appliances are heated by inputting AC power. When the AC voltage fluctuates, the electric power will fluctuate more, and stable temperature control cannot be achieved. In order to achieve better temperature control effects, it is necessary to detect the AC voltage and obtain the actual AC voltage. The actual heating power of the heating element can be obtained more accurately. The expected temperature control effect can be achieved by adjusting the power devices of the heating equipment according to the actual heating power.

[0027] See also Figures 1 to 2 A household heating device includes a circuit board having an integrated detection circuit. The detection circuit includes a mains voltage detection unit and a mains input mains voltage detection unit. The mains power is capable of at least supplying power to the power components of the household heating device. An electrical switch is provided between the input mains power and the power components of the household heating device. An MCU is integrated into the circuit board. The MCU sends a power control signal based on the detection voltage to control the on / off of the electrical switch. By obtaining the actual mains voltage, the actual heating power of the heating component can be obtained more accurately. By adjusting the power components of the heating device according to the actual heating power, the desired temperature control effect can be achieved. The MCU can also be an intelligent control module.

[0028] Combine Figure 3 and Figure 4 The mains voltage detection unit includes a rectifier circuit, a current limiting circuit, a photoelectric coupler, a sampling circuit and a filter circuit. The mains power is input into the mains detection unit through the mains input terminal. The rectifier circuit and the current limiting circuit are located between the mains input terminal and the photoelectric coupler. The sampling circuit and the filter circuit are located downstream of the photoelectric coupler. A detection voltage is output through the voltage detection terminal connected to the filter circuit. Figure 3 and Figure 4 The main differences are: Figure 3 In the example, the rectifier circuit is located upstream of the current limiting circuit. Figure 4The rectifier circuit is located downstream of the current limiting circuit. The voltage detection circuit does not use a transformer, making the circuit smaller. In addition, the use of a photocoupler can avoid the risk of electric shock to the user during voltage detection. For a specific circuit connection diagram, see Figure 5-Figure 14 .

[0029] See also Figure 5 In this embodiment, the mains voltage detection unit includes a rectifier circuit, a current limiting circuit, a photoelectric coupler, a sampling circuit, and a filter circuit. The sampling circuit and the filter circuit are located downstream of the photoelectric coupler. A detection voltage is output through a voltage detection terminal OUT1 connected to the filter circuit; the voltage detection terminal OUT1 is connected to the MCU so that the detection voltage can be input into the MCU.

[0030] Among them, the rectifier circuit is a diode D6, which will be referred to as the first diode for ease of description. The current limiting circuit includes a current limiting resistor R35. The mains input terminal includes a mains hot line input terminal L and a mains neutral line input terminal N. The mains hot line input terminal is electrically connected to the current limiting resistor R35 via a diode D6. The output end of the current limiting resistor R35 is electrically connected to the first end 1 of the optocoupler IC4, and the mains neutral line input terminal is electrically connected to the second end 2 of the optocoupler IC4. The sampling circuit includes a sampling resistor R44. The third end 3 of the optocoupler is electrically connected to one end of the sampling resistor R44, the other end of the sampling resistor R44 is grounded, the fourth end 4 of the optocoupler is electrically connected to a voltage source VCC, and one end of the filter circuit is electrically connected to the third end 3 of the optocoupler, and the other end of the filter circuit is grounded. In this embodiment, the photocoupler IC4 includes a light-emitting diode (LED) and a phototransistor (PTD). The LED includes a first end and a second end of the photocoupler, and the phototransistor includes a third end and a fourth end of the photocoupler. The first end is the anode of the LED, the second end is the cathode of the LED, the third end is the emitter of the phototransistor, and the fourth end is the collector of the phototransistor. The output end of the current-limiting resistor R35 is connected to the anode of the LED, the cathode of the LED is connected to the cathode N of the mains input, the collector of the phototransistor is electrically connected to the voltage source VCC, the emitter of the phototransistor is electrically connected to one end of a sampling resistor R44, and the other end of the sampling resistor R44 is grounded. The current at the front end of the photocoupler IC4 is a first current I1, i.e., the current passing through the current-limiting resistor R35 is the first current. The current at the back end of the photocoupler IC4 is a second current I2, i.e., the current passing through the sampling resistor R44 is the second current, and the second current is proportional to the first current. The voltage corresponding to the sampling resistor R44 is the second voltage, and the peak voltage of the second voltage is U2.

[0031] In this embodiment, the rectifier circuit includes a first diode D6, which is located between the positive electrode H of the mains input terminal and the current limiting resistor R35; through the half-wave rectification of the first diode D6, a half-wave rectified signal of the mains can be obtained, such as Figure 16 As shown; relative to the input mains voltage, the waveform of the mains voltage is a sine wave with a peak value of U1, as shown Figure 15 As shown, after passing through the first diode, the rectified voltage waveform is above the X-axis, that is, there is only forward voltage, and the peak value of the rectified voltage is U D , U D =U1-U 压降 , U 压降 is the voltage drop generated by the first diode D6. After passing through the first diode D6, the current of the circuit is the first current I1, I1=(U1-U 压降 ) / R 35 The current at the third terminal of the photocoupler is the second current I2, which is proportional to the first current. The current size is determined by selecting a photocoupler with appropriate specifications based on actual needs.

[0032] Figure 6 The circuit connection diagram of the second embodiment of the detection circuit is as follows: compared with the first embodiment, the detection circuit further includes a zero point detection circuit, the zero point detection detection circuit includes a rectifier circuit, a current limiting circuit and a photoelectric coupler, the zero point detection circuit further includes a zero point detection terminal OUT2, a second resistor R31 and a second capacitor C21, one end of the second resistor R31 is connected to the third end of the photoelectric coupler IC4, the other end of the second resistor R31 is connected to one end of the second capacitor C21, the other end of the second capacitor C21 is grounded, the zero point detection terminal OUT2 is connected to the other end of the second resistor R31, and the zero point detection terminal OUT2 is connected to the MCU so that the MCU can obtain the current zero point. Generally, adjusting the power device includes controlling the zero-crossing on and off, and the control requires obtaining the current zero point, which can reduce harmonic interference; in this way, the zero point detection circuit and the voltage detection circuit can share some electrical components and circuits, making the circuit connection simple, with fewer electrical components and lower cost, without using a mutual inductor, making the circuit volume smaller, and using a photoelectric coupler to avoid the risk of electric shock to the user during voltage detection.

[0033] Figure 7 The circuit connection diagram of the third embodiment of the detection circuit is compared with the first embodiment. The rectifier circuit includes a rectifier bridge BD1. The rectifier bridge BD1 includes four diodes. There is a connection terminal between adjacent diodes, two of which are connected to the positive and negative electrodes of the mains input terminal, another connection terminal is connected to the current limiting resistor R35, and another connection terminal is connected to the second end of the photocoupler. This embodiment can obtain a full-wave rectified signal of the mains through the rectifier bridge, such as Figure 7As shown in the figure; relative to the input mains voltage, the waveform of the mains voltage is a sine wave with a peak value of U1. The rectified voltage waveform is above the X-axis, that is, there is only a forward voltage, and the peak value of the rectified voltage is U D , its period is half of the original; U D =U1-U 压降 , U 压降 is the voltage drop generated by the rectifier bridge BD1. After passing through the rectifier bridge, the current of the circuit is the first current I1, I1=(U1-U 压降 ) / R 35 The current at the third terminal of the photocoupler is the second current I2, which is proportional to the first current. The current size is determined by selecting a photocoupler with appropriate specifications based on actual needs.

[0034] Figure 8 This is a circuit connection diagram of the fourth embodiment of the detection circuit. Compared with the third embodiment, the detection circuit also includes a zero-point detection circuit, which includes a zero-point detection terminal OUT2, a second resistor R31 and a second capacitor C21. One end of the second resistor R31 is connected to the third end of the photoelectric coupler IC4, the other end of the second resistor R31 is connected to one end of the second capacitor C21, and the other end of the second capacitor C21 is grounded. The zero-point detection terminal OUT2 is connected to the other end of the second resistor R31, and the zero-point detection terminal OUT2 is connected to the MCU so that the MCU can obtain the current zero point. Generally, adjusting the power device includes controlling the zero-crossing on and off. This control requires obtaining the current zero point, which can reduce harmonic interference. In this way, the zero-point detection circuit and the voltage detection circuit can share some electrical components and circuits, making the circuit connection simple, with fewer electrical components and lower cost. No mutual inductor is used, making the circuit volume smaller, and the use of a photoelectric coupler avoids the risk of electric shock to the user during voltage detection.

[0035] Figure 9 This is a circuit connection diagram of a fifth embodiment of a detection circuit. Compared to the second embodiment, the third terminal 3 of the photocoupler is grounded, the sampling resistor R44 is electrically connected between the fourth terminal 4 of the photocoupler and a voltage source Vcc, one terminal of the filter circuit is electrically connected to the fourth terminal of the photocoupler, and the other terminal of the filter circuit is grounded. The voltage detection terminal OUT1 is located downstream of the filter circuit. The detection circuit also includes a zero-point detection circuit, the input terminal of which is connected to the fourth terminal 4 of the photocoupler. Of course, the zero-point detection circuit can also be omitted.

[0036] Figure 10It is a circuit connection diagram of the sixth embodiment of the detection circuit; compared with the second embodiment, the rectifier circuit is a first diode D6, the current limiting circuit includes a current limiting resistor R35, the mains live wire input end is electrically connected to the first end 1 of the photoelectric coupler through the first diode D6, and the mains neutral wire input end is electrically connected to the second end 1 of the photoelectric coupler through the current limiting resistor R35.

[0037] Figure 11 It is a circuit connection diagram of the seventh embodiment of the detection circuit; compared with the second embodiment, the rectifier circuit is a first diode D6, the current limiting circuit includes a current limiting resistor R35, the input end of the mains positive pole is electrically connected to the first end 1 of the photoelectric coupler, and the mains neutral line input end is electrically connected to the second end 2 of the photoelectric coupler through the first diode D6 and the current limiting resistor R35.

[0038] Figure 12 It is a circuit connection diagram of the eighth embodiment of the detection circuit; compared with the second embodiment, the rectifier circuit is a first diode D6, the current limiting circuit includes a current limiting resistor R35, the mains live wire input end is electrically connected to the first end 1 of the photoelectric coupler through the current limiting resistor R35, and the mains neutral wire input end is electrically connected to the second end 1 of the photoelectric coupler through the first diode D6.

[0039] Figure 13 This is a circuit connection diagram of a ninth embodiment of a detection circuit. Compared to the sixth embodiment, the third terminal 3 of the photocoupler is grounded, the sampling resistor R44 is electrically connected between the fourth terminal 4 of the photocoupler and a voltage source Vcc, one terminal of the filter circuit is electrically connected to the fourth terminal of the photocoupler, and the other terminal of the filter circuit is grounded. The voltage detection terminal OUT1 is located downstream of the filter circuit. The detection circuit also includes a zero-point detection circuit, the input of which is connected to the fourth terminal 4 of the photocoupler. Of course, the zero-point detection circuit may also be omitted.

[0040] Figure 14 This is a circuit connection diagram of a tenth embodiment of a detection circuit. Compared to the fourth embodiment, the third terminal 3 of the electric coupler is grounded, the sampling resistor R44 is electrically connected between the fourth terminal 4 of the photocoupler and a voltage source Vcc, one terminal of the filter circuit is electrically connected to the fourth terminal of the photocoupler, and the other terminal of the filter circuit is grounded. The voltage detection terminal OUT1 is located downstream of the filter circuit. The detection circuit also includes a zero-point detection circuit, the input terminal of which is connected to the fourth terminal 4 of the photocoupler. Of course, the zero-point detection circuit can also be omitted.

[0041] In the above embodiment, the filter circuit includes a first resistor R41 and a first capacitor C26. One end of the first resistor R41 is connected to the third end of the photocoupler IC4, and the other end of the first resistor R41 is connected to the voltage detection terminal OUT1. One end of the first capacitor C26 is connected to the other end of the first resistor R41, and the other end of the first capacitor C26 is grounded. Through the filter circuit, the voltage output at the voltage detection terminal OUT1 is the third voltage U3. The waveform of the third voltage is as follows: Figure 8 shown.

[0042] In the above embodiment, the detection circuit may further include a second diode D7, which is located between the AC input terminal and the optocoupler. Since the light emitting diode of the optocoupler has a low voltage resistance, the second diode D7 is provided to prevent the light emitting diode from being broken down.

[0043] In the above embodiment, the peak value of the mains voltage is the first voltage U1, the peak value of the voltage corresponding to the sampling resistor R44 is the second voltage U2, and the voltage obtained by the voltage detection terminal OUT1 is the third voltage U3. The first voltage and the third voltage satisfy the following relationship: U1 = A1U3 + B1, and the first voltage and the second voltage satisfy the following relationship: U1 = A2U2 + B2, where A1 and A2 are different and constant, and B1 and B2 are different and constant. In this way, as long as the third voltage is obtained, it can be determined that it is the peak value of the voltage, and the actual heating power of the heating element can be obtained relatively accurately. The desired temperature control effect can be achieved by adjusting the power device according to the actual heating power.

[0044] It should be noted that the above embodiments are only used to illustrate the present invention and are not intended to limit the technical solutions described in the present invention. Although this specification has described the present invention in detail with reference to the above embodiments, it should be understood by those skilled in the art that the present invention can still be modified or replaced by equivalents, and all technical solutions and improvements thereof that do not depart from the spirit and scope of the present invention should be included in the scope of the claims of the present invention.

Claims

1. A detection circuit for a household appliance, the detection circuit comprising a mains voltage detection unit, the mains voltage detection unit comprising a rectifier circuit, a current limiting circuit, a photoelectric coupler, a sampling circuit, and a filter circuit, the mains power being input to the mains voltage detection unit via a mains input terminal, the rectifier circuit and the current limiting circuit being located between the mains input terminal and the photoelectric coupler, the sampling circuit and the filter circuit being located downstream of the photoelectric coupler, and the detection voltage being output via a voltage detection terminal connected to the filter circuit; The current limiting circuit includes a current limiting resistor, the rectifier circuit is a rectifier bridge, the rectifier bridge includes four diodes, and a connection end is provided between adjacent diodes, two of which are connected to the mains input end, another connection end is connected to the current limiting resistor, and another connection end is connected to the second end of the photoelectric coupler; The detection circuit further includes a zero point detection circuit, which includes the rectifier circuit, the current limiting circuit, and the photoelectric coupler. The zero point detection circuit also includes a second resistor and a second capacitor, one end of the second resistor is connected to the sampling circuit, the other end of the second resistor is connected to one end of the second capacitor, the other end of the second capacitor is grounded, and the zero point detection end is connected to the other end of the second resistor; The detection circuit further includes a second diode, the second diode being located between the photocoupler and the mains input terminal; The mains voltage is input from the mains input terminal, the peak value of the mains voltage is the first voltage U1, the peak value of the voltage corresponding to the sampling resistor is the second voltage U2, and the voltage obtained by the voltage detection terminal is the third voltage U3. The first voltage and the third voltage satisfy the following relationship: U1=A1U3+B1, and the first voltage and the second voltage satisfy the following relationship: U1=A2U2+B2, where A1 is different from A2 and is a constant, and B1 is different from B2 and is a constant.

2. The detection circuit according to claim 1, wherein: The rectifier circuit is a diode, the current limiting circuit includes a current limiting resistor, the mains input end includes a mains live wire input end and a mains neutral wire input end, the mains live wire input end is electrically connected to the current limiting resistor through the diode, the output end of the current limiting resistor is electrically connected to the first end of the photoelectric coupler, and the mains neutral wire input end is electrically connected to the second end of the photoelectric coupler; Alternatively, the rectifier circuit is a diode, the current limiting circuit includes a current limiting resistor, the mains live wire input end is electrically connected to the first end of the photocoupler through the diode, and the mains neutral wire input end is electrically connected to the second end of the photocoupler through the current limiting resistor; or, the rectifier circuit is a diode, the current limiting circuit includes a current limiting resistor, the mains live wire input end is electrically connected to the first end of the photocoupler, and the mains neutral wire input end is electrically connected to the second end of the photocoupler through the diode and the current limiting resistor.

3. The detection circuit according to claim 2, wherein: The third end of the photoelectric coupler is electrically connected to one end of the sampling circuit, the other end of the sampling circuit is grounded, the fourth end of the photoelectric coupler is electrically connected to a voltage source, one end of the filter circuit is electrically connected to the third end of the photoelectric coupler, and the other end of the filter circuit is grounded; the voltage detection end is located downstream of the filter circuit.

4. The detection circuit according to claim 2, wherein: The third end of the photoelectric coupler is grounded, the sampling circuit is electrically connected between the fourth end of the photoelectric coupler and a voltage source, one end of the filter circuit is electrically connected to the fourth end of the photoelectric coupler, and the other end of the filter circuit is grounded; the voltage detection end is located downstream of the filter circuit.

5. The detection circuit according to claim 3, wherein: The photocoupler includes a light-emitting diode and a phototransistor, wherein the anode of the light-emitting diode is electrically connected to the first end, the cathode of the diode is electrically connected to the second end, the collector of the phototransistor is electrically connected to the fourth end, and the emitter of the phototransistor is electrically connected to the third end.

6. The detection circuit according to claim 4, wherein: The photocoupler includes a light-emitting diode and a phototransistor, wherein the anode of the light-emitting diode is electrically connected to the first end, the cathode of the diode is electrically connected to the second end, the collector of the phototransistor is electrically connected to the fourth end, and the emitter of the phototransistor is electrically connected to the third end.

7. The detection circuit according to claim 3, wherein: The filtering circuit includes a first resistor and a first capacitor, one end of the first resistor is connected to the third end of the photoelectric coupler, the other end of the first resistor is connected to the voltage detection end, one end of the first capacitor is connected to the other end of the first resistor, and the other end of the first capacitor is grounded.

8. The detection circuit according to claim 4, wherein: The filtering circuit includes a first resistor and a first capacitor, one end of the first resistor is connected to the fourth end of the photoelectric coupler, the other end of the first resistor is connected to the voltage detection end, one end of the first capacitor is connected to the other end of the first resistor, and the other end of the first capacitor is grounded.

9. A household heating device, comprising a circuit board, wherein the circuit board has the detection circuit described in any one of claims 1 to 8 above, the household heating device comprising a toilet heater, an instant hot water dispenser, a portable water dispenser, and an instant hot constant temperature faucet, and the household heating device can be powered by a mains input, an electric switching device is provided between the mains input terminal and the power device of the household heating device, and an MCU is integrated in the circuit board, and the MCU sends a power control signal according to the detection voltage to control the on and off of the electric switching device.

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