CN214412257U

CN214412257U - Electric leakage protection device and electric appliance

Info

Publication number: CN214412257U
Application number: CN202120028200.3U
Authority: CN
Inventors: 王唯; 官阔荣
Original assignee: Zhejiang Supor Water Heater Co ltd
Current assignee: Zhejiang Supor Water Heater Co ltd
Priority date: 2021-01-04
Filing date: 2021-01-04
Publication date: 2021-10-15
Anticipated expiration: 2031-01-04

Abstract

The embodiment of the utility model provides an earth leakage protection device and including its electrical apparatus. The leakage protection device comprises a power supply circuit, wherein the power supply circuit comprises a grounding end, a boost converter and an inductor, the grounding end is used for connecting the negative pole of a battery, the input end of the boost converter is used for connecting the positive pole of the battery, and the inductor is connected with the boost converter in parallel; and the power supply input end of the detection circuit is connected with the output end of the boost converter. The battery is used for supplying power to the detection circuit, so that the problems that the leakage protection device does not work when the external power grid is powered off and the detection accuracy and reliability of the leakage protection device are reduced due to voltage fluctuation of the external power grid can be solved. In addition, the earth leakage protection device can be used as a front detection device for an electric appliance. Therefore, before the electric appliance is used, the leakage protection device can detect whether the power supply leaks electricity and protect the electric appliance, so that the electric shock accident is effectively avoided.

Description

Electric leakage protection device and electric appliance

Technical Field

The utility model relates to an earth leakage protection field of electrical apparatus, more specifically relate to an earth leakage protection device and including its electrical apparatus.

Background

The current safety hazard of various electric equipment such as household appliances is mainly the problem of electric leakage, and accidents of electric shock of users caused by electric leakage in the using process of the electric equipment are endless. Therefore, an earth leakage protection device is required to ensure the safety of the user.

In the prior art, some leakage protection devices are realized by simple leakage switches, but the leakage protection devices have higher requirements on the installation environment of the electrical appliance, for example, the electrical appliance is required to have good ground connection, otherwise, the reliability of the electrical appliance is difficult to ensure. With the increasing demands of people on the reliability of the earth leakage protection device, the earth leakage protection device becomes more and more complex. The leakage protection device comprises more and more electrical elements and has more and more complex working principle. The operation of these earth leakage protection devices typically requires a power input.

However, in the prior art, the earth leakage protection device and the electrical appliance share the same power circuit, which causes the mutual influence of the power supply of the earth leakage protection device and the electrical appliance, and the starting or stopping of the electrical appliance may cause the unstable power voltage of the earth leakage protection device. In addition, the power circuit is usually externally connected to the utility power, and the voltage fluctuation of the utility power itself may cause the power voltage of the leakage protection device to be unstable. Even in the event of a power outage to the external power grid may cause the earth leakage protection device to be inoperative. These all seriously affect the reliability and accuracy of the earth leakage protection device.

SUMMERY OF THE UTILITY MODEL

The present invention has been made in view of the above problems. According to an aspect of the present invention, there is provided an earth leakage protection device, comprising a power circuit, the power circuit comprising a grounding terminal, a boost converter and an inductor, wherein the grounding terminal is used for connecting a negative electrode of a battery, an input terminal of the boost converter is used for connecting a positive electrode of the battery, and the inductor is connected in parallel with the boost converter; and the power supply input end of the detection circuit is connected with the output end of the boost converter.

The leakage protection device is independent of the electric appliance and can be provided with a power supply for the detection circuit by arranging an independent power supply circuit. The stability of the power supply voltage of the detection circuit is guaranteed, the leakage protection device is not affected by an electric appliance when in work, and the leakage protection device plays a more accurate and reliable leakage protection role. In addition, the battery is used for supplying power to the detection circuit, so that the problems that the leakage protection device does not work when the external power grid is powered off and the detection accuracy and reliability of the leakage protection device are reduced due to voltage fluctuation of the external power grid can be solved. In addition, the earth leakage protection device can be used as a front detection device for an electric appliance. Therefore, before the electric appliance is used, the leakage protection device can detect whether the power supply leaks electricity and protect the electric appliance, so that the electric shock accident is effectively avoided.

Illustratively, the boost converter is implemented using a switching power supply chip.

The function of utilizing the switching power supply chip to realize boost converter is easy to realize, and the integrated level is high moreover, practices thrift area. In addition, the circuit connection in the leakage protection device is reduced, the damage of the device caused by the disconnection between electronic elements in the leakage protection device is effectively avoided, and the service life of the leakage protection device is prolonged.

Illustratively, the output end of the boost converter is an output pin of the switching power supply chip, the output pin of the switching power supply chip is further connected with a first resistance voltage divider, a feedback input pin of the switching power supply chip is connected with a central point of the first resistance voltage divider, and a compensation capacitor is further connected between the output pin of the switching power supply chip and the central point of the first resistance voltage divider.

Therefore, the switching power supply chip can monitor the output voltage through the feedback input pin. When the load varies, the power supply circuit may be adjusted based on the monitoring result, thereby outputting a stable desired voltage to the detection circuit. Thereby ensuring that the leakage protection function of the leakage protection device can be normally executed

Illustratively, an output pin of the switching power supply chip is connected to the power supply input of the detection circuit and the first resistor divider via a diode.

Due to its high integration, the switching power supply chip may introduce more interference signals. Because the diode has one-way conductivity, the anti-interference performance of the output voltage of the switching power supply chip can be effectively improved. The stability of the output voltage of the switching power supply chip is ensured, and the reliability of the leakage protection device is further ensured.

Illustratively, the enable pin of the switching power supply chip is grounded via the first filter capacitor.

The first filter capacitor is arranged to smoothly filter the external peak voltage interference of the switching power supply chip. Therefore, the switching power supply chip can stably work and output stable expected voltage to the detection circuit. Therefore, the protection effect of the leakage protection device is further ensured

Illustratively, the output of the boost converter is connected to the power input of the detection circuit via a diode.

The diode has unidirectional conductivity. The output end of the boost converter is connected to the detection circuit through the diode, so that the anti-interference performance of the output voltage of the switching power supply chip can be effectively improved. The stability of the output voltage of the boost converter is ensured, and the reliability of the leakage protection device is further ensured.

Illustratively, the detection circuit includes: the main control circuit and the triode driving circuit;

the main control circuit comprises an optical coupling circuit and a main control chip; the opto-coupler circuit includes the input zero line, input live wire and input ground wire, the input zero line, connect the current limiting resistance between arbitrary two in input live wire and the input ground wire, the signal transmission end and the diode of opto-coupler, the signal receiving terminal of opto-coupler connects main control chip, the input zero line, still be connected with the relay on each in input live wire and the input ground wire, the signal control end of relay connects main control chip via triode drive circuit, main control chip is used for the signal control relay according to the signal receiving terminal who comes from the opto-coupler, the signal receiving terminal of opto-coupler, the output of boost converter is still connected to relay and main control chip, with be its power supply by power supply circuit.

The detection circuit is used for realizing the leakage protection function of the leakage protection device. Even if weak current is generated in the optical coupler circuit, the optical coupler can also output a corresponding level signal to the main control chip, and the result obtained by the main control chip is accurate and reliable. When abnormal conditions such as power supply wire connection error or loss, electrical appliance shell electrification, namely ground wire electrification or ground wire loss and the like occur, the main control chip can control the on-off of the relay switch according to the obtained level signal, so that the electrical appliance can be prevented from working, and the occurrence of electric shock accidents is avoided. Therefore, the leakage protection function of the leakage protection device can be safely and intelligently executed.

The leakage protection device further comprises an alarm circuit, the alarm circuit comprises an indicator light circuit and/or a buzzer circuit, the indicator light circuit and/or the buzzer circuit is connected with the main control chip to alarm under the control of the main control chip, and the indicator light circuit and/or the buzzer circuit is further connected with the output end of the boost converter to be powered by the power circuit.

The alarm circuit can remind a user when the detection circuit detects the electric leakage condition, so that the user is prevented from getting an electric shock. The setting of alarm circuit makes earth leakage protection device's earth leakage protection function more perfect to the user can learn concrete electric leakage part according to the colour of LED pilot lamp, has reduced the degree of difficulty, has reduced work load for maintenance work afterwards.

Illustratively, the input end of the boost converter is connected with a second resistor divider, and the central point of the second resistor divider is connected with the main control chip.

Therefore, the main control chip can monitor the output voltage of the battery in real time through the second resistor divider. The user can be prompted to replace the battery in time under the condition that the electric quantity of the battery is insufficient. The problems that the output voltage of the power circuit is unstable due to the fact that the battery power is too low, and therefore the leakage detection result of the detection circuit is influenced are effectively solved. Thus, the leakage protection device can be ensured to work normally.

Exemplarily, a central point of the second resistor divider is connected to the main control chip via a filter resistor, and one end of the filter resistor connected to the main control chip is further grounded via a second filter capacitor.

The filter resistor and the second filter capacitor are arranged in the circuit for sampling and detecting the output voltage of the battery by the main control chip, so that the interference of other circuits and/or electronic elements to the sampling and detecting process is effectively reduced, and the error is reduced. Therefore, the maximum utilization of the electric quantity of the battery can be realized, and resources are saved.

According to another aspect of the present invention, an electrical appliance is provided. The appliance comprises an earth leakage protection device as described above.

The electric appliance provided with the electric leakage protection device can perform electric leakage self-checking before use, and can also detect whether the electric leakage condition occurs in real time in the use process, so that the use safety of the electric appliance is ensured, the occurrence of electric shock accidents is effectively avoided, and casualties are reduced. In addition, because the power supply circuit of the leakage protection device in the electric appliance is independent of the power supply circuit of the electric appliance, the stability of the power supply voltage is ensured, so that the leakage protection device is not influenced by the electric appliance when in work, and the leakage protection device plays a more accurate and reliable role in leakage protection. Finally, because the leakage protection device is powered by the battery, the problems that the leakage protection device does not work when the external power grid is powered off and the detection accuracy and reliability of the leakage protection device are reduced due to the voltage fluctuation of the external power grid can be solved. Thus, the safety of the electric appliance is ensured.

The above description is only an overview of the technical solutions of the present invention, and in order to make the technical means of the present invention more clearly understood, the present invention may be implemented according to the content of the description, and in order to make the above and other objects, features, and advantages of the present invention more obvious and understandable, the following detailed description of the present invention is given.

Drawings

The above and other objects, features and advantages of the present invention will become more apparent by describing in more detail embodiments of the present invention with reference to the attached drawings. The accompanying drawings are included to provide a further understanding of the embodiments of the invention, and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description, serve to explain the invention and not to limit the invention. In the drawings, like reference numbers generally represent like parts or steps.

Fig. 1 shows a schematic block diagram of an earth leakage protection device according to an exemplary embodiment of the present invention;

fig. 2 shows a schematic diagram of a power supply circuit in a residual current device according to an exemplary embodiment of the present invention;

fig. 3 shows a schematic diagram of a detection circuit in an electrical leakage protection device according to an exemplary embodiment of the present invention;

fig. 4 shows a schematic diagram of an alarm circuit in a leakage protection device according to an exemplary embodiment of the present invention.

Wherein the figures include the following reference numerals:

100. a power supply circuit; 110. an inductance; 120. a boost converter; 130. a ground terminal; 140. a switching power supply chip; 150. a first resistive divider; 160. a second resistive divider; 200. a detection circuit; 210. an optocoupler circuit; 211. a first optical coupling branch; 212. a second optical coupling branch; 213. a third optical coupling branch; 220. a main control chip; 230. a triode drive circuit; 300. an alarm circuit; 310. an indicator light circuit; 320. a buzzer circuit.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, exemplary embodiments according to the present invention will be described in detail below with reference to the accompanying drawings. It is to be understood that the described embodiments are merely exemplary of the present invention and are not intended to limit the invention to the particular embodiments described herein. Based on the embodiments of the present invention described in the present application, all other embodiments obtained by those skilled in the art without creative efforts shall fall within the protection scope of the present invention.

In a conventional electric appliance, an earth leakage protection device and an electric appliance main body commonly share the same power supply circuit. This results in the start-up and shut-down of the appliance inevitably affecting the power supply stability of the earth leakage protection device. In particular, electrical appliances such as water heaters, which may be frequently started and stopped during operation. It is precisely during its operation that the user may be in the immediate vicinity of the water heater, and that the environment may also be humid and of high conductivity. Therefore, if the detection result of the earth leakage protection device is affected due to frequent start-up and shut-down of the water heater, adverse results can be caused. In addition, the power circuit is usually externally connected to the utility power, and the instability of the utility power will also seriously affect the reliability and accuracy of the earth leakage protection device. Even when the external power grid is powered off, the earth leakage protection device may not work.

According to the utility model discloses an aspect provides an earth leakage protection device. Fig. 1 shows a schematic block diagram of an earth leakage protection device according to an embodiment of the present invention. As shown in fig. 1, the leakage protection device includes a power supply circuit 100 and a detection circuit 200. The detection circuit 200 is used to detect whether the protected electrical appliance has an electrical leakage condition. The power supply circuit 100 is used to supply power to the detection circuit 200. The power supply circuit 100 is an independent circuit independent of the power supply circuit of the electrical appliance protected by the earth leakage protection device. The power supply circuit 100 includes a ground terminal 130, a boost converter 120, and an inductor 110. The ground terminal 130 is used for connecting the negative electrode of the battery. The input of the boost converter 120 is used to connect the positive pole of the battery. The inductor 110 is connected in parallel with the boost converter 120. The power input of the detection circuit 200 is connected to the output of the boost converter 120 to be supplied with power by the power circuit 100.

For example, one or more batteries may be used to power the earth leakage protection device. The battery may be a dry cell battery, a lithium battery, or the like. As shown in fig. 1, the input terminal of the boost converter 120 is connected to the positive pole of the battery, and the ground terminal 130 is connected to the negative pole of the battery. The boost converter 120 and the inductor 110 are connected in parallel between the battery and the detection circuit 200. The battery is used to input direct current to the boost converter 120 and the inductor 110. Boost converter 120 and inductor 110 may work together to boost the input voltage to a larger output voltage. In this application, the input voltage is the voltage of the battery, and the input voltage may be 1.5V, 3V, or the like, depending on the battery. For example, the boost converter 120 may include electronic components such as capacitors and switches. When the switch in the boost converter 120 is in the conducting state, the inductor 110 can store the resulting dc power. When the switch in the boost converter 120 is in the off state, the inductor 110 may discharge the stored dc power. The output voltage value of the output terminal of the boost converter 120 at this time may be the sum of the voltage value of the direct current discharged from the inductor 110 and the input voltage value of the battery. It will be appreciated that this sum is greater than the input voltage. That is, the boost converter 120 and the inductor 110 perform a boosting function. The desired output voltage value may be obtained by varying the time of turn-on and turn-off of the switches in the boost converter 120 and/or the parameters of the inductor 110. The output voltage value may be, for example, 5V and/or 12V, depending on the requirements of the detection circuit 200. In the above process, the switch in the boost converter 120 is continuously turned on and off at a high frequency, so as to control the inductor 110 to continuously store and release energy. Finally, the output voltage value can gradually tend to be balanced and stabilized at the expected output voltage value. The frequency at which the switch is turned on and off is high and is nearly invisible to the user. The output of the boost converter 120 is connected to the power input of the detection circuit 200 for providing the required dc power to the detection circuit 200. The detection circuit 200 may be used to detect electrical leakage in an appliance with a desired dc power supply.

By providing a separate power supply circuit 100 to supply power to the detection circuit 200, the earth leakage protection device is independent of the appliance. This ensures the stability of the supply voltage of the detection circuit 200, so that the earth leakage protection device is not affected by the electrical appliance when in operation, and plays a more accurate and reliable role in earth leakage protection. In addition, the battery is used for supplying power to the detection circuit 200, so that the problems that the leakage protection device does not work when the external power grid is powered off and the detection accuracy and reliability of the leakage protection device are reduced due to voltage fluctuation of the external power grid can be solved. In addition, the earth leakage protection device can be used as a front detection device for an electric appliance. Therefore, before the electric appliance is used, the leakage protection device can detect whether the power supply leaks electricity and protect the electric appliance, so that the electric shock accident is effectively avoided.

Illustratively, the output of the boost converter 120 may be connected to the power input of the detection circuit 200 via a diode. The diode has unidirectional conductivity. The output end of the boost converter 120 is connected to the detection circuit 200 via a diode, so that the interference immunity of the output voltage of the switching power supply chip 140 can be effectively improved. The stability of the output voltage of the boost converter 120 is ensured, and the reliability of the earth leakage protection device is ensured.

Fig. 2 shows a schematic diagram of a power supply circuit 100 in a leakage protection device according to an exemplary embodiment of the present invention.

Illustratively, the boost converter 120 may be implemented with a switching power supply chip 140. Preferably, the switching power supply chip 140 may adopt a power supply chip with low quiescent current to reduce the power consumption of the leakage protection device. As shown in fig. 2, a battery may be accessed at CN7 to provide direct current. Terminal 2 at CN7 is used to connect the positive pole of the battery. Terminal 1 at CN7 is connected to ground 130 of power supply circuit 100 and is used to connect the negative pole of the battery. Terminal 2 also connects power supply pin V of switching power supply chip 140 and inductor 110. The switching power supply chip 140 may have an internal switch integrated therein, and a switch pin connected to the internal switch is provided thereon as an output pin SW thereof. The internal switch may be a high speed MOS transistor. The internal switches can be controlled to be turned on and off at high speed by internal Pulse Width Modulation (PWM) or Pulse Frequency Modulation (PFM) of the switching power supply chip 140. Alternatively, the duty ratios of the high level and the low level of the PWM pulse of the switching power supply chip 140 may be set. Thereby, the on and off times of the internal switch can be changed. As can be seen from the above description, the voltage value output by the output pin SW of the switching power chip 140 includes the voltage value of the inductor 110 for releasing power and the voltage value of the battery input. By setting the duty cycle and the parameters of the inductor 110, a desired output voltage value can be obtained. It is understood that the output pin SW of the switching power supply chip 140 is an output terminal of the boost converter 120. The output pin SW of the switching power supply chip 140 and the inductor 110 are connected to a power supply input terminal of the detection circuit 200. That is, in this scheme, the switching power supply chip 140 and the inductor 110 are connected in parallel between a terminal for connecting a battery and the detection circuit 200 for supplying power to the detection circuit 200 using the battery.

The function of the boost converter 120 realized by the switching power supply chip 140 is easy to realize, the integration level is high, and the occupied area is saved. In addition, the circuit connection in the leakage protection device is reduced, the damage of the device caused by the disconnection between electronic elements in the leakage protection device is effectively avoided, and the service life of the leakage protection device is prolonged.

Illustratively, the enable pin CE of the switching power supply chip 140 may be grounded via the first filter capacitor. As shown in fig. 2, the enable pin CE is grounded via a first filter capacitor C23. Generally, the enable pin CE may be switched to a high level to enable the switching power supply chip 140 to operate normally. The first filter capacitor C23 is provided to smooth out the external spike voltage interference of the switching power chip 140. Accordingly, the switching power supply chip 140 can be operated stably to output a stable desired voltage to the detection circuit 200. Therefore, the protection effect of the leakage protection device is further ensured.

As described above, the output terminal of the boost converter 120 is the output pin SW of the switching power supply chip 140. Illustratively, the output pin SW of the switching power supply chip 140 may also be connected to the first resistor divider 150. The feedback input pin FB of the switching power supply chip 140 may be connected to the center point of the first resistive divider 150. It is understood that the center point does not mean that the resistances before and after it are 1/2 of the total resistance of the first resistive divider 150, but only means that there is a portion of the resistance of the first resistive divider 150 before and after it. A compensation capacitor C19 may also be connected between the output pin SW of the switching power supply chip 140 and the center point of the first resistor divider 150. As shown in FIG. 2, the first resistive divider 150 includes a resistor R43 and a resistor R50 separated by a center point. The resistance values of the resistor R43 and the resistor R50 may be the same or different. The feedback input pin FB of the switching power supply chip 140 is connected to a center point between the resistor R43 and the resistor R50. The output pin SW of the switching power supply chip 140 is also connected to the center point via the compensation capacitor C19. Generally, the input voltage required for the feedback input FB is a low magnitude voltage. The output voltage of the switching power supply chip 140 and the inductor 110 may be divided by the resistor R43 and the resistor R50, and then input to the feedback input pin FB. The feedback input pin FB can monitor the output voltage. For example, as the load to which the power supply circuit 100 is connected increases, the energy required by the load increases. At this time, the output voltage will become low, and the input voltage of the feedback input pin FB will also become low. The on-time of the internal switches can be increased by changing the duty cycle of the PWM pulses of the switching power supply chip 140. An increase in the on-time of the internal switch means an increase in the energy stored in the inductor 110, so that the output voltage can be increased and stabilized to a desired voltage. Meanwhile, the compensation capacitor C19 is arranged in the circuit, so that the output voltage is more stable.

Thus, the switching power supply chip 140 can monitor the output voltage through the feedback input pin FB. When the load varies, the power supply circuit 100 may be adjusted based on the monitoring result, thereby outputting a stable desired voltage to the detection circuit 200. And further, the normal execution of the leakage protection function of the leakage protection device is ensured.

As shown in fig. 2, the output pin SW of the switching power chip 140 may connect the power input terminal of the detection circuit 200 and the first resistor divider 150 via a diode D9. Due to the high integration of the switching power supply chip 140, it may introduce more interference signals. Because the diode has unidirectional conductivity, the anti-interference performance of the output voltage of the switching power supply chip 140 can be effectively improved. The stability of the output voltage of the switching power supply chip 140 is ensured, and the reliability of the leakage protection device is further ensured.

Fig. 3 shows a schematic diagram of a detection circuit 200 of a leakage protection device according to an exemplary embodiment of the present invention. As shown in fig. 3, the detection circuit 200 may include a main control circuit and a transistor driving circuit 230. The master control circuit may include an optocoupler circuit 210 and a master control chip 220. The optical coupling circuit 210 includes an input neutral line, an input live line, and an input ground line. Any two of the input zero line, the input live wire and the input ground wire are connected with a current limiting resistor, a signal sending end of an optical coupler and a diode. The signal receiving end of the optical coupler is connected with the main control chip 220. And each of the input zero line, the input live wire and the input ground wire is also connected with a relay. The signal control terminal of the relay is connected to the main control chip 220 via the triode drive circuit 230. The main control chip 220 is used for controlling the relay according to a signal from a signal receiving end of the optical coupler. The signal receiving end of the optocoupler, the relay and main control chip 220 are also connected to the output end of the boost converter 120 to be supplied with power by the power circuit 100.

When the power circuit 100 supplies power to the detection circuit 200, the optical coupling circuit 210 and the main control chip 220 in the detection circuit 200 can work normally. As shown in fig. 3, the optical coupling circuit 210 includes a first optical coupling branch 211, a second optical coupling branch 212, and a third optical coupling branch 213. In the first optical coupler branch 211, an anode of a signal transmitting end of an optical coupler U1 is connected with an input neutral line through a plurality of stages of series current limiting resistors R01, R02, R03 and R04. And the cathode of the signal sending end of the optical coupler U1 is connected with the anode of the diode D5. The cathode of diode D5 is connected to the input hot. And the collector of the signal receiving end of the optical coupler U1 is connected with an INT0 pin of the main control chip 220. The output of the step-up converter 120 is connected to the collector via a resistor R05 to supply the first optical coupler branch 211. And an emitter of a signal receiving end of the optical coupler U1 is grounded. The collector of the signal receiving end of the optical coupler U1 is grounded through a capacitor C6. In the second optical coupling branch 212, the anode of the signal transmitting end of the optical coupler U2 is connected with the input live wire through a plurality of stages of series current limiting resistors R06, R07, R08 and R09. And the cathode of the signal sending end of the optical coupler U2 is connected with the anode of the diode D4. The cathode of diode D4 is connected to input ground. And the collector of the signal receiving end of the optical coupler U2 is connected with an INT1 pin of the main control chip 220. The output of the step-up converter 120 is connected to the collector via a resistor R10 for supplying the second optical coupler branch 212. And an emitter of a signal receiving end of the optical coupler U2 is grounded. The collector of the signal receiving end of the optocoupler U2 is also grounded via a capacitor C4. In the third optical coupling branch 213, the anode of the signal transmitting end of the optical coupler U3 is connected with the input neutral wire through the series current limiting resistors R11 and R12. And the cathode of a signal sending end of the optocoupler U3 is connected with the anode of the diode D2 through series current limiting resistors R13 and R14. The cathode of diode D2 is connected to input ground. And the collector of the signal receiving end of the optical coupler U3 is connected with an INT2 pin of the main control chip 220. The output of the step-up converter 120 is connected to the collector via a resistor R15 for supplying power to the third optical coupler branch 213. And an emitter of a signal receiving end of the optical coupler U3 is grounded. The collector of the signal receiving end of the optocoupler U3 is also grounded via a capacitor C2.

One end of the input neutral, input live and input ground is used to connect to an external grid such as 220V. The other end of the input ground line is used for grounding. The other ends of the input zero line and the input live wire are used for connecting an electric appliance. And each of the input zero line, the input live wire and the input ground wire is also respectively connected with a relay. One end of the relay is connected to the output terminal of the boost converter 120, and the other end is connected to the collector of the triode. The emitters of the three transistors are connected and grounded, thereby forming a transistor drive circuit 230. The pins P-REL1, P-REL2 and P-REL3 of the main control chip 220 are respectively connected with the base electrodes of three triodes for controlling the on-off of the relay.

The operation of the earth leakage protection device according to an embodiment of the present invention is described in detail below.

(1) The main control chip 220 outputs high-level start signals to the transistors Q1, Q2, and Q3, and the transistor driving circuit 230 is turned on. Therefore, the relay generates magnetic force when current passes through the relay, and the switches K1, K2 and K3 are attracted to form a passage.

(2) And reading level values respectively output by optocouplers U1, U2 and U3 in a positive half cycle and a negative half cycle between an input zero line, an input live line and an input ground line in an external power grid current period. Taking the optical coupling branch 211 as an example, when the input zero line and the input live line are both normally connected, in 5 milliseconds before the sine wave of the grid voltage, the current direction is from the input zero line to the multistage series current limiting resistors R01, R02, R03 and R04, and then the current direction reaches the input live line through the optical coupling U1 and the diode D5. The optocoupler U1 is turned on to trigger a signal receiving end of the optocoupler U1, so that a collector and an emitter are turned on, and the level of the INT0 pin of the main control chip 220 is pulled down to obtain a low level less than 5 milliseconds, and the low level is recorded as 0. When the sine wave of the grid voltage enters the last 5 milliseconds, namely the negative half cycle, the diode D5 has one-way conductivity, and current cannot pass through the optocoupler U1, so that the optocoupler U1 cannot conduct. Therefore, the INT0 pin of the main control chip 220 becomes high for more than 5 msec, which is denoted as 1.

(3) The main control chip 220 compares the received level signal with a preset value, and determines whether the situation is normal according to the comparison result, thereby controlling the relay. If the relay is judged to be normal, the switches K1 and K2 of the relay are allowed to be closed, and the control switch K3 is opened; if the abnormal situation is judged, the switches K1, K2 and K3 of the control relay are all turned off.

The detection circuit 200 is utilized to realize the leakage protection function of the leakage protection device. Even if weak current is generated in the optical coupling circuit 210, the optical coupling can also output a corresponding level signal to the main control chip 220, and the result obtained by the main control chip 220 is accurate and reliable. When abnormal conditions such as power supply wire connection error or loss, electrical appliance shell electrification, namely ground wire electrification or ground wire loss and the like occur, the main control chip 220 can control the on-off of the relay switch according to the obtained level signal, so that the electrical appliance can be prevented from working, and the occurrence of electric shock accidents is avoided. Therefore, the leakage protection function of the leakage protection device can be safely and intelligently executed.

Optionally, the earth leakage protection device may further comprise an alarm circuit. Fig. 4 shows a schematic diagram of an alarm circuit 300 of a leakage protection device according to an exemplary embodiment of the present invention. The alarm circuit 300 includes an indicator light circuit 310 and/or a buzzer circuit 320. The indicator light circuit 310 is connected to the main control chip 220, which may include a Light Emitting Diode (LED). The buzzer circuit 320 may also be connected to the main control chip 220. Thus, the alarm circuit can alarm under the control of the main control chip 220. The indicator lamp circuit 310 is also connected to the output of the boost converter 120 to be powered by the power circuit 100. The buzzer circuit 320 is also connected to the output of the boost converter 120, similar to the indicator lamp circuit 310.

As shown in fig. 4, in the indicator light circuit 310, the light emitting diodes LED1, LED2, LED3, LED4, LED5, and LED6 are connected in series with resistors R30, R31, R32, R33, R34, and R35, respectively, and these series circuits are connected in parallel. One end of the indicator light circuit 310 is connected to the output end of the boost converter 120, and the other end is connected to the pin P-LED1, the pin P-LED2, the pin P-LED3, the pin P-LED4, the pin P-LED5, and the pin P-LED6 of the main control chip 220. Table 1 shows a preset truth table for the LED indicator lights in the indicator light circuit in different situations where the appliance power connections are different. Wherein the on and off of the LED indicator light represent different values of "1" and "0", respectively. It will be appreciated by those skilled in the art that a bi-color LED indicator may also be implemented, with different colors illuminated to represent different values. As described above, the main control chip 220 may receive the level signal, compare the level signal with the preset truth table, determine which of the preset truth tables the current situation belongs to, and turn on the light accordingly.

TABLE 1 Preset truth table

In the buzzer circuit 320, the buzzer BUZ is connected in parallel with the resistor R36 and then connected in series with the resistor R37. One end of the buzzer circuit 320 is connected to the output end of the boost converter 120, and the other end is connected to the P-BUZ pin of the main control chip 220. When the electrical appliance protected by the leakage protection device is abnormal, the buzzer BUZ gives an alarm to a user for prompting.

The alarm circuit 300 can remind the user when the detection circuit 200 detects the leakage condition, so as to avoid electric shock of the user. The setting of the alarm circuit 300 makes the leakage protection function of the leakage protection device more perfect, and the user can know the specific leakage part according to the color of the LED indicating lamp, thereby reducing the difficulty and the workload for the subsequent maintenance work.

Illustratively, the input end of the boost converter 120 is connected to the second resistor divider 160, and the central point of the second resistor divider 160 is connected to the main control chip 220. As shown in fig. 2, the input terminal of the boost converter 120 is a power supply pin V of the switching power supply chip. The second resistor divider 160 is shown as including a resistor R48 and a resistor R49. Power pin V is connected to the center point between resistor R48 and resistor R49. Similarly to the center point of the first resistive divider 150, the center point of the second resistive divider 160 also does not indicate that it divides the second resistive divider 160 into equal two resistances. It can be understood that the resistor R48 and the resistor R49 can be implemented by using resistors with higher resistance values, so as to reduce the power consumption of the earth leakage protection device. The output voltage of the battery can be divided by the two resistors and then output to the BAT-AD pin of the main control chip 220, so that the main control chip 220 performs sampling detection on the output voltage of the battery. As described above, the main control chip 220 is also connected to the alarm circuit 300. When the main control chip 220 detects that the output voltage of the battery is less than a threshold, it can be determined that the battery is insufficient. The threshold value may be preset in the main control chip 220. The main control chip 220 may prompt the user to replace the battery in time by controlling the indicator circuit 310 and/or the buzzer circuit 320 in the alarm circuit 300. It will be appreciated that the indicator light circuit 310 and/or the buzzer circuit 320 may prompt the user in a different manner than the above-described prompt for a user of a current leakage condition, and is not limited herein.

Thus, the main control chip 220 can monitor the output voltage of the battery in real time via the second resistor divider 160. The user can be prompted to replace the battery in time under the condition that the electric quantity of the battery is insufficient. The problem that the output voltage of the power circuit 100 is unstable due to the over-low battery power, so that the leakage detection result of the detection circuit 200 is influenced is effectively solved. Thus, the leakage protection device can be ensured to work normally.

As shown in fig. 2, the center point of the second resistor divider 160 may be connected to the main control chip 220 through a filter resistor R5, and one end of the filter resistor R5 connected to the main control chip 220 is also grounded through a second filter capacitor C18.

The filter resistor R5 and the second filter capacitor C18 are arranged in the circuit for sampling and detecting the output voltage of the battery by the main control chip 220, so that the interference of other circuits and/or electronic elements to the sampling and detecting process is effectively reduced, and the error is reduced. Therefore, the maximum utilization of the electric quantity of the battery can be realized, and resources are saved.

According to another aspect of the present invention, an electrical appliance is provided. The appliance comprises an earth leakage protection device as described above. Before a user starts to use the electric appliance or in the using process of the electric appliance, the electric leakage detection can be carried out on the power supply of the electric appliance or the electric appliance by using the electric leakage protection device. For example, the input wires in the power cord are missing or misconnected, or the electrical casing is leaky. The operation of the earth leakage protection device is as described above, and will not be described herein.

The electric appliance provided with the electric leakage protection device can perform electric leakage self-checking before use, and can also detect whether the electric leakage condition occurs in real time in the use process, so that the use safety of the electric appliance is ensured, the occurrence of electric shock accidents is effectively avoided, and casualties are reduced. Moreover, because the power supply circuit 100 of the leakage protection device in the electrical appliance is independent of the power supply circuit of the electrical appliance, the stability of the power supply voltage is ensured, so that the leakage protection device is not influenced by the electrical appliance when in work, and a more accurate and more reliable leakage protection effect is achieved. Finally, because the leakage protection device is powered by the battery, the problems that the leakage protection device does not work when the external power grid is powered off and the detection accuracy and reliability of the leakage protection device are reduced due to the voltage fluctuation of the external power grid can be solved. Thus, the safety of the electric appliance is ensured.

For purposes of description, the term "connected" may be used herein to describe one or more elements or features shown in a figure in relation to other elements or features. It should be understood that "connected" may include directly connected or indirectly connected via other elements or features, all of which are intended to be encompassed herein.

It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments according to the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, elements, components, and/or combinations thereof, unless the context clearly indicates otherwise.

It should be noted that the terms "first," "second," and the like in the description and claims of this application and in the drawings described above are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used is interchangeable under appropriate circumstances such that the embodiments of the application described herein are capable of operation in sequences other than those illustrated or described herein.

The present invention has been described in terms of the above embodiments, but it is to be understood that the above embodiments are for purposes of illustration and description only and are not intended to limit the invention to the described embodiments. Furthermore, it will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, and that many more modifications and variations are possible in light of the teaching of the present invention and are within the scope of the invention as claimed. The scope of the invention is defined by the appended claims and equivalents thereof.

Claims

1. An earth leakage protection device, comprising:

the power supply circuit comprises a grounding end, a boost converter and an inductor, wherein the grounding end is used for connecting the negative pole of a battery, the input end of the boost converter is used for connecting the positive pole of the battery, and the inductor is connected with the boost converter in parallel; and

and the power supply input end of the detection circuit is connected with the output end of the boost converter.

2. A leakage protection device according to claim 1, wherein the boost converter is implemented by using a switching power supply chip.

3. The leakage protection device of claim 2, wherein the output terminal of the boost converter is an output pin of the switching power chip, the output pin of the switching power chip is further connected to a first resistor divider, a feedback input pin of the switching power chip is connected to a central point of the first resistor divider, and a compensation capacitor is further connected between the output pin of the switching power chip and the central point of the first resistor divider.

4. A leakage protection device according to claim 3, wherein an output pin of the switching power supply chip is connected to the power supply input of the detection circuit and the first resistor divider via a diode.

5. The earth leakage protection device of claim 2, wherein the enable pin of the switching power supply chip is grounded via the first filter capacitor.

6. A leakage protection device according to claim 1, wherein the output of the boost converter is connected to the power input of the detection circuit via a diode.

7. A residual current device according to any of the claims 1 to 6, characterized in that said detection circuit comprises: the main control circuit and the triode driving circuit;

the main control circuit comprises an optical coupling circuit and a main control chip;

the optical coupling circuit comprises an input zero line, an input live wire and an input ground wire, a current limiting resistor and a signal sending end of an optical coupler and a diode are connected between any two of the input zero line, the input live wire and the input ground wire, a signal receiving end of the optical coupler is connected with the main control chip, a relay is further connected to each of the input zero line, the input live wire and the input ground wire, a signal control end of the relay is connected with the main control chip through a triode driving circuit, the main control chip is used for controlling the relay according to a signal from the signal receiving end of the optical coupler,

the signal receiving end of the optical coupler, the relay and the main control chip are further connected with the output end of the boost converter, so that the power circuit supplies power to the boost converter.

8. An earth leakage protection device according to claim 7, characterized in that said earth leakage protection device further comprises an alarm circuit, said alarm circuit comprises an indicator light circuit and/or a buzzer circuit, said indicator light circuit and/or said buzzer circuit is connected to said main control chip for alarming under the control of said main control chip, said indicator light circuit and/or said buzzer circuit is further connected to the output terminal of said boost converter for being powered by said power supply circuit.

9. The earth leakage protection device of claim 8, wherein a second resistor divider is connected to the input terminal of the boost converter, and a center point of the second resistor divider is connected to the main control chip.

10. The earth leakage protection device of claim 9, wherein a center point of the second resistor divider is connected to the main control chip via a filter resistor, and one end of the filter resistor connected to the main control chip is further grounded via a second filter capacitor.

11. An electrical appliance comprising a residual current device according to any one of claims 1 to 10.