Circuit for coil breakage detection and circuit breaker comprising same

Abstract

The utility model provides a circuit for coil disconnection detection and a circuit breaker comprising the same, and is characterized in that the circuit comprises a filtering module which is configured to receive a voltage signal associated with a coil and output a filtered voltage signal to a comparator; the threshold setting module is configured to output a threshold signal to the comparator; the comparator comprises a positive phase input end, a negative phase output end and an output end, the positive phase input end is connected to the filtering module to receive the filtered voltage signal, the negative phase output end is connected to the threshold setting module to receive the threshold signal, and the output end outputs an output signal generated based on comparison of the filtered voltage signal and the threshold signal; the bias module is connected between the positive phase input end and the output end of the comparator; and a processing module configured to receive the output signal of the comparator and determine whether the coil is broken based on whether the rising edge and the falling edge of the output signal are detected.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a circuit, in particular, to a circuit for coil open circuit detection and a circuit breaker comprising the same. BACKGROUND

[0002] A plurality of iron core coils are usually included in a compact circuit breaker (CCB), and when one or more coils are open-circuited, the circuit breaker cannot work normally, so it is very important to accurately detect whether the coil is open-circuited.

[0003] Generally, whether the coil is open-circuited can be detected by measuring the current or the voltage. When whether the coil is open-circuited is detected by measuring the current, a high-power shunt resistor and a high-precision operational amplifier need to be connected in series on each coil, and as the number of coils increases, the layout space of the circuit board is insufficient. When whether the coil is open-circuited is detected by measuring the voltage, the accurate detection cannot be realized due to the leakage current of the rectifier bridge and other factors.

[0004] To solve the above problems, the present disclosure provides a circuit for coil open circuit detection. According to the circuit provided by the present disclosure, the element arrangement requirement can be met without arranging a large number of elements on the circuit board, and the interference of the leakage current of the rectifier bridge and other factors on the coil open circuit detection can be avoided, so that whether the coil is open-circuited can be accurately detected. SUMMARY

[0005] According to an aspect of the present disclosure, a circuit for coil open circuit detection is provided, characterized in that the circuit comprises: a filtering module configured to receive a voltage signal associated with a coil and output a filtered voltage signal to a comparator; a threshold setting module configured to output a threshold signal to the comparator; the comparator comprises a positive phase input end, a negative phase output end and an output end, the positive phase input end is connected to the filtering module to receive the filtered voltage signal, the negative phase output end is connected to the threshold setting module to receive the threshold signal, and the output end outputs an output signal generated based on the comparison of the filtered voltage signal and the threshold signal; a biasing module connected between the positive phase input end and the output end of the comparator; and a processing module configured to receive the output signal of the comparator and determine whether the coil is open-circuited based on whether a rising edge and a falling edge of the output signal are detected.

[0006] In some examples, the filtering module comprises an input end, an output end, a first resistor and a first capacitor, wherein a first end of the first resistor is connected to the input end of the filtering module and a second end is connected to the output end of the filtering module, and a first end of the first capacitor is grounded and a second end is connected to the output end of the filtering module.

[0007] In some examples, the threshold setting module includes a second resistor, a third resistor, a second capacitor, and an output terminal, wherein a first terminal of the second resistor is connected to a power supply and a second terminal of the second resistor is connected to the output terminal of the threshold setting module, a first terminal of the third resistor is grounded and a second terminal of the third resistor is connected to the output terminal of the threshold setting module, and the second capacitor is connected in parallel across the third resistor.

[0008] In some examples, the second resistor and the third resistor are pre-set such that a voltage value of the threshold signal is between 0 volt and 0.8 volt.

[0009] In some examples, the biasing module includes a fourth resistor and a fifth resistor, wherein a first terminal of the fourth resistor is connected to the power supply and a second terminal of the fourth resistor is connected to a positive input terminal of the comparator, a first terminal of the fifth resistor is connected to the positive input terminal of the comparator and a second terminal of the fifth resistor is connected to an output terminal of the comparator.

[0010] In some examples, the processing module is configured to determine that the coil is wired based on detecting a rising edge and a falling edge of the output signal existing within a detection period, and determine that the coil is wirelessly based on not detecting a rising edge or a falling edge of the output signal existing within the detection period.

[0011] In some examples, the detection period is 20 milliseconds.

[0012] In some examples, the circuit further includes an enabling module connected between the processing module and the output terminal of the threshold setting module and configured to receive a detection enabling signal from the processing module, and a level conversion module connected between the output terminal of the comparator and the processing module and configured to receive the output signal from the comparator and output a converted output signal to the processing module.

[0013] In some examples, the enabling module includes an input terminal, a sixth resistor, and a transistor, wherein a first terminal of the sixth resistor is connected to the input terminal of the enabling module and a second terminal of the sixth resistor is connected to a base of the transistor, an emitter of the transistor is grounded and a collector of the transistor is connected to the output terminal of the threshold setting module.

[0014] In some examples, the level conversion module includes an input terminal, a diode, a seventh resistor, an eighth resistor, a third capacitor, and an output terminal, wherein a first terminal of the diode is connected to the input terminal and a second terminal of the diode is connected to a first terminal of the seventh resistor, a second terminal of the seventh resistor is connected to the output terminal of the level conversion module, a first terminal of the eighth resistor is connected to the power supply and a second terminal of the eighth resistor is connected to the output terminal of the level conversion module, and a first terminal of the third capacitor is grounded and a second terminal of the third capacitor is connected to the output terminal of the level conversion module.

[0015] In some examples, the processing module is further configured to determine that the coil is wirelessly based on the converted output signal being a high level signal greater than a first threshold voltage.

[0016] According to another aspect of the present application, there is provided a circuit breaker comprising a circuit as previously described. BRIEF DESCRIPTION OF DRAWINGS

[0017] Aspects, features and advantages of the present application will become more apparent and readily appreciated from the following description of embodiments, taken in conjunction with the accompanying drawings in which:

[0018] Figure 1 a block diagram of a circuit including a coil to be detected is shown;

[0019] Figure 2 a block diagram of a circuit for coil open line detection according to an embodiment of the present disclosure is shown;

[0020] Figure 3 a schematic diagram of a circuit for coil open line detection according to an embodiment of the present disclosure is shown;

[0021] Figure 4 a block diagram of another circuit for coil open line detection according to an embodiment of the present disclosure is shown; and

[0022] Figure 5 a schematic diagram of another circuit for coil open line detection according to an embodiment of the present disclosure is shown. DETAILED DESCRIPTION

[0023] The present application will now be described in detail with reference to exemplary embodiments thereof. However, the present application is not limited to the embodiments described herein, which can be implemented in various forms. The described embodiments are merely for the purpose of enabling the present application to be thoroughly and completely understood, and to convey the concept of the present application to those skilled in the art. Features of the described embodiments can be combined or replaced with each other, unless explicitly excluded or should be excluded according to the context.

[0024] In the embodiments of the present application, unless explicitly stated otherwise, "connection", "connection" does not mean "direct connection" or "direct contact", but only requires electrical communication. In addition, "first", "second", etc. or similar expressions in this paper are only for description and differentiation purposes, and do not indicate any priority or order, and cannot be understood as indicating or implying the relative importance of the corresponding components, nor representing whether the described parameter values are the same or different.

[0025] Figure 1 a block diagram of a circuit including a coil to be detected is shown.

[0026] As Figure 1As shown, the circuit can include coils CT1 and CT2, rectification modules 110 and 120, a power taking module 130, a shunt module 140, and a feedback module 150.

[0027] Coils CT1 and CT2 can be connected to rectification modules 110 and 120, respectively. Rectification modules 110 and 120 can be connected to power taking module 130 and shunt module 140. Feedback module 150 can be connected between power taking module 130 and shunt module 140. It should be noted that although Figure 1 Only coils CT1 and CT2 are shown, but more or less coils can be included, and other coils can be connected in the circuit in a similar manner as coils CT1 and CT2.

[0028] When it is needed to detect whether coils CT1 and CT2 are broken, whether coils CT1 and CT2 are broken can be detected based on a voltage signal associated with coil CT1 and a voltage signal associated with coil CT2, respectively. Generally, when a coil is in line, the voltage signal associated with the coil can be an alternating voltage signal. In some embodiments, when a coil is in line, the voltage signal associated with the coil can be an alternating voltage signal with a magnitude between -0.7V and 13V. When a coil is broken, the voltage signal associated with the coil should be a low level signal or zero. Therefore, whether a coil is broken can be detected by setting a proper threshold. When the voltage signal associated with a coil is greater than the threshold, then it can be determined that the coil is in line, and when the voltage signal associated with a coil is less than the threshold, then it can be determined that the coil is broken.

[0029] However, when the coils are connected as Figure 1 shown, if coil CT1 is in line while coil CT2 is broken, due to the influence of the leakage current that can exist in the path including coil CT1, and power taking module 130 and shunt module 140, etc., even though coil CT2 is broken, the voltage signal associated with coil CT2 can still be greater than the threshold, so coil CT2 can still be falsely determined to be in line. Similarly, when coil CT1 is broken while coil CT2 is in line, due to similar reasons, coil CT1 can also still be falsely determined to be in line. To solve the above problems, the present disclosure proposes a circuit for coil broken detection. Unlike existing circuits for coil broken detection, the circuit for coil broken detection proposed by the present disclosure sets a proper threshold by taking advantage of the characteristic that the voltage signal associated with a coil always has a negative voltage value, thereby avoiding false determination of coil broken.

[0030] Figure 2 A block diagram of a circuit for coil broken detection according to an embodiment of the present disclosure is shown.

[0031] As Figure 2As shown, the circuit for coil open detection can include a filtering module 210, a threshold setting module 220, a comparator 230, a biasing module 240, and a processing module 250.

[0032] The filtering module 210 can receive a voltage signal associated with the coil and filter the voltage signal to remove harmonic components in the voltage signal, thereby avoiding interference of the harmonic components in the voltage signal associated with the coil to the coil open detection. In some embodiments, the filtering module 210 can be implemented as a low pass RC filter. The filtering module 210 can be connected to the comparator 230 to provide the filtered voltage signal to the comparator 230.

[0033] The threshold setting module 220 can provide a threshold signal by resistive voltage division. The threshold setting module 220 can be connected to the comparator 230 to provide the threshold signal to the comparator 230. In some embodiments, the threshold setting module 220 can be configured to provide the threshold signal with a specific voltage value, which can be associated with a negative voltage value of the voltage signal associated with the coil in the case that the coil is online. In some embodiments, the negative voltage value of the voltage signal associated with the coil in the case that the coil is online can be between -0.8 volts (V) and 0 V, and thus, the voltage value of the threshold signal can be between 0 V and 0.8 V. In some embodiments, the voltage value of the threshold signal can be 0.2 V.

[0034] The comparator 230 can include a positive input, a negative input, and an output. The positive input of the comparator 230 can receive the filtered voltage signal, and the negative input can receive the threshold signal. The comparator 230 can output a high level signal when the input voltage of the positive input is greater than the input voltage of the negative input, and output a low level signal when the input voltage of the positive input is less than the input voltage of the negative input.

[0035] Considering the working characteristics of the comparator 230, the inputs of the positive input terminal and the negative input terminal should be positive values, therefore, the voltage signal associated with the coil needs to be biased to offset the part of the voltage signal associated with the coil that can include negative voltage values to positive voltage values. In some embodiments, when the coil to be detected is broken, the voltage signal associated with the coil is a low level signal, so that the input voltage of the positive input terminal of the comparator 230 (the voltage signal associated with the coil) is less than the input voltage of the negative input terminal (the threshold signal), and therefore the comparator 230 outputs a low level signal. In some embodiments, when the coil to be detected is online, there should be a part of the voltage signal associated with the coil that is less than the threshold signal, so that the input voltage of the positive input terminal of the comparator 230 (the voltage signal associated with the coil) is periodically greater than the input voltage of the negative input terminal (the threshold signal), and therefore the comparator 230 outputs a pulse signal in which high level and low level appear alternately. In some embodiments, when the coil to be detected changes from online to broken, if the current output of the comparator 230 is still high level, due to the presence of the biasing module 240 and the coil changing from online to broken, the input voltage of the positive input terminal of the comparator 230 (the voltage signal associated with the coil) is greater than the input voltage of the negative input terminal (the threshold signal), and therefore the comparator 230 continues to output a high level signal, and if the current output of the comparator 230 is low level, due to the presence of the biasing module 240, the input voltage of the positive input terminal of the comparator 230 (the voltage signal associated with the coil) is less than the input voltage of the negative input terminal (the threshold signal) for a period of time, and then becomes greater than the input voltage of the negative input terminal (the threshold signal), and therefore the comparator 230 continues to output a low level signal for a period of time and then changes to output a high level signal.

[0036] The voltage signal associated with the coil can be biased from low level to higher level, so that the input voltage of the positive input terminal of the comparator 230 (the voltage signal associated with the coil) is greater than the input voltage of the negative input terminal (the threshold signal), and therefore the comparator 230 outputs a high level signal. Therefore, when the coil is online, the comparator 230 can output a pulse signal in which high level and low level appear alternately, and when the coil is broken, the comparator 230 can output a low level signal or a high level signal, it should be noted that, as described above, when the coil is broken, the high level signal output by the comparator 230 can include a rising edge jumping from low level to high level.

[0037] The biasing module 240 can be connected between the output terminal and the positive input terminal of the comparator 230 for biasing the voltage signal associated with the coil. The threshold setting module 220 can also adjust the voltage of the threshold signal accordingly according to the biasing operation of the biasing module 240 on the voltage signal associated with the coil.

[0038] The processing module 250 can determine whether the coil is broken based on the voltage of the output signal output by the comparator 230. As previously described, when the coil is online, the comparator 230 can output a pulse signal in which a high level and a low level alternately appear, and when the coil is broken, the comparator 230 can output a low level signal or a high level signal. Accordingly, the processing module 250 can be configured to determine whether the coil is broken based on whether a rising edge and a falling edge of the output signal are detected. Specifically, when the processing module 250 detects a rising edge and a falling edge of the output signal within a detection period, it is determined that the coil is online, and when the processing module 250 does not detect a rising edge or a falling edge of the output signal within the detection period, it is determined that the coil is broken. In some embodiments, the detection period can be set to 20 ms.

[0039] In some embodiments, each coil can correspond to one circuit for coil break detection. In some embodiments, each coil can correspond to one circuit including the filtering module 210, the comparator 230, the biasing module 240, and the processing module 250, and the threshold setting module 220 can be shared by a plurality of coils.

[0040] Reference will be made to Figure 3 descriptions Figure 2 circuit diagram of the block diagram shown.

[0041] Figure 3 A schematic diagram of a circuit for coil break detection according to an embodiment of the present disclosure is shown.

[0042] As Figure 3 shown, the filtering module can include an input IN1, a first resistor R1, a first capacitor C1, and an output OUT1. A first end of the first resistor R1 is connected to the input IN1 and a second end is connected to the output OUT1, and a first end of the first capacitor C1 is grounded and a second end is connected to the output OUT1. A voltage signal associated with the coil can be input to the filtering module via the input IN1 and filtered. The filtered voltage signal can be output to the comparator.

[0043] The threshold setting module can include a second resistor R2, a third resistor R3, a second capacitor C2 and an output terminal OUT2. A first terminal of the second resistor R2 is connected to a power supply and a second terminal is connected to the output terminal OUT2, a first terminal of the third resistor R3 is grounded and a second terminal is connected to the output terminal OUT2, and the second capacitor C2 is connected in parallel across the third resistor R3. In some embodiments, the second resistor R2 can be 200 kΩ and the third resistor R3 can be 30 kΩ, such that the threshold setting module can output a threshold signal of about 0.4 V to the comparator via the output terminal OUT2. However, the present disclosure is not limited thereto, and the second resistor R2 and the third resistor R3 can be pre-set to any resistor with a proper resistance value, such that the threshold setting module can output a threshold signal with a voltage value between 0 V and 0.8 V to the comparator via the output terminal OUT2.

[0044] The biasing module can include a fourth resistor R4 and a fifth resistor R5. One terminal of the fourth resistor R4 is connected to a power supply and a second terminal is connected to a positive input terminal of the comparator, and the fifth resistor R5 can be connected between an output terminal and the positive input terminal of the comparator. In some embodiments, the fourth resistor R4 and the fifth resistor R5 can each be 3.3 MΩ. However, the present disclosure is not limited thereto, and the fourth resistor R4 and the fifth resistor R5 can have a resistance value between 10 K and 20 M.

[0045] The comparator can include a positive input terminal IN+, a negative input terminal IN- and an output terminal OUT. In addition, the comparator can also include a power supply pin V+ and a ground pin V-. When an input voltage of the positive input terminal is greater than an input voltage of the negative input terminal, the comparator can output a high level signal, and when the input voltage of the positive input terminal is less than the input voltage of the negative input terminal, the comparator can output a low level signal. As described with reference to Figure 2 As described with reference to

[0046] The processing module can be implemented as a micro control unit (MCU), however the present disclosure is not limited thereto. As described with reference to Figure 2 The processing module can be based on the received output signal of the comparator, and determine whether the coil is on or off based on the output signal. When the processing module detects that the output signal has a rising edge and a falling edge within a detection period, it can be determined that the coil is on, and when the processing module does not detect that the output signal has a rising edge or a falling edge within the detection period, it can be determined that the coil is off. In some embodiments, the detection period can be set to 20 ms.

[0047] Figure 4 A block diagram of another circuit for coil open detection according to an embodiment of the present disclosure is shown.

[0048] As shown in Figure 4 , the circuit for coil open detection can include a filtering module 210, a threshold setting module 220, a comparator 230, a biasing module 240, a processing module 250, an enabling module 260, and a level conversion module 270. The filtering module 210, the threshold setting module 220, the comparator 230, and the biasing module 240 have similar configurations as the filtering module 210, the threshold setting module 220, the comparator 230, and the biasing module 240 shown in Figure 2 , which will not be repeated here.

[0049] The enabling module 260 can receive a detection enable signal from the processing module 250, which can have a high level. The enabling module 260 can be connected to the output of the threshold setting module 220. In some embodiments, when the enabling module 260 receives the detection enable signal with a high level, the voltage at the output of the threshold setting module 220 can be pulled down to zero, and thus the input voltage at the negative input of the comparator 230 can be zero. Subsequently, the detection enable signal disappears, and the input voltage at the negative input of the comparator 230 returns to the voltage of the threshold signal.

[0050] By introducing the enabling module 260, some problems caused by the biasing module 240 can be solved. As described with reference to Figure 2 and Figure 3 , when the coil to be detected changes from being online to being open, if the output of the comparator 230 outputs a low level signal at this time, since the biasing module 240 pulls down the input voltage at the positive input of the comparator 230, the input voltage at the positive input of the comparator 230 will still be less than the input voltage at the negative input (the voltage of the threshold signal) for a period of time, which can cause certain interference to the coil open detection. Therefore, by pulling down the input voltage at the negative input of the comparator 230 to zero through the enabling module 260, when the coil to be detected changes from being online to being open, even if the output of the comparator 230 still outputs a low level signal at this time and the biasing module 240 still pulls down the input voltage at the positive input of the comparator 230, the input voltage at the positive input of the comparator 230 will still be greater than the input voltage at the negative input, so that the comparator 230 outputs a high level signal. In this case, compared with Figure 2 and Figure 3The difference is that the high level signal output by the comparator 230 when the coil is broken can not include a rising edge from low level to high level.

[0051] The level conversion module 270 can perform level conversion on the output signal of the comparator. Specifically, the level conversion module 270 can keep the high level signal and the pulse signal output by the comparator 230 as the high level signal and the pulse signal, and convert the low level signal output by the comparator 230 into a pulse signal. The level conversion module 270 can provide the converted output signal to the processing module 250. In this case, the processing module 250 can be configured to determine whether the coil is broken based on whether a rising edge and a falling edge exist in the converted output signal. Specifically, when the processing module 250 detects that a rising edge and a falling edge exist in the converted output signal within a detection period, it is determined that the coil is online, and when the processing module 250 does not detect that a rising edge or a falling edge exists in the converted output signal within the detection period, it is determined that the coil is broken. In some embodiments, the detection period can be set to 20 ms. In addition, the processing module 250 can also be configured to determine that the coil is broken based on determining that the converted output signal is a high level signal greater than a first threshold voltage. In some embodiments, the first threshold voltage can be 2.1 volts.

[0052] Figure 5 A schematic diagram of another circuit for coil breakage detection according to an embodiment of the present disclosure is shown.

[0053] Figure 5 The configurations and connection modes of the filter module, the bias module, the threshold setting module, the comparator, and the processing module in the shown circuit schematic diagram are the same as those in the circuit schematic diagram shown in FIG. 2, and will not be repeated here. Figure 3 The configurations and connection modes of the corresponding modules in the shown circuit schematic diagram are the same as those in the circuit schematic diagram shown in FIG. 2, and will not be repeated here.

[0054] As Figure 5As shown, the enable module can include an input IN2, a sixth resistor R6, a transistor Q and an output OUT3. The input IN2 of the enable module can be connected to the processing module to receive the detection enable signal from the processing module. The first end of the sixth resistor R6 can be connected to the input IN2 and the second end can be connected to the base of the transistor Q, the emitter of the transistor Q is grounded and the collector is connected to the output OUT2 of the threshold setting module. When the enable module receives the detection enable signal with a high level from the processing module, the transistor Q enters the saturation mode, so that the voltage of the output OUT2 of the threshold setting module is pulled down to zero (ground). When the detection enable signal disappears, the transistor Q is turned off, and the voltage of the output OUT2 of the threshold setting module returns to the voltage of the threshold signal. The level conversion module can include an input, a diode D, a seventh resistor R7, an eighth resistor R8, a third capacitor C3 and an output, wherein the first end of the diode D is connected to the input and the second end is connected to the first end of the seventh resistor R7, the second end of the seventh resistor R7 is connected to the output of the level conversion module, the first end of the eighth resistor R8 is connected to the power supply and the second end is connected to the output of the level conversion module, the first end of the third capacitor C3 is grounded and the second end is connected to the output of the level conversion module. In some embodiments, the seventh resistor R7 can be 10 kilo-ohms and the eighth resistor R8 can be 1 mega-ohms. However, the present disclosure is not limited thereto, the seventh resistor R7 and the eighth resistor R8 can have any appropriate resistance. When the level conversion module receives a high level signal or a pulse signal from the comparator, the level conversion module can output a high level signal or a pulse signal, and when the level conversion module receives a low level signal from the comparator, the diode D is turned off, the seventh resistor R7 and the eighth resistor R8 are divided, and the level conversion module can output a high level signal.

[0055] It should be noted that, for the sake of clarity and conciseness, only parts related to the embodiments of the present application are shown in the drawings, but those skilled in the art should understand that the devices or apparatuses shown in the drawings can include other necessary units.

[0056] The block diagrams of the circuits, devices, apparatuses, equipment and systems involved in the present application are only exemplary examples and are not intended to require or imply that the connections, arrangements and configurations shown in the block diagrams must be made. As those skilled in the art will realize, these circuits, devices, apparatuses, equipment and systems can be connected, arranged and configured in any way as long as the desired purpose can be achieved. The numbers involved in the present application are only illustrative.

[0057] Those skilled in the art can clearly understand that, for the sake of convenience and brevity, the specific working process of the above-described system, device and unit can refer to the corresponding process in the foregoing method embodiments, which will not be described here.

[0058] In several embodiments provided in the present application, it should be understood that the disclosed system, device, can be implemented in other manners. For example, the embodiments of the device described above are merely schematic; for example, the division of the units is only a logical function division; there can be another division manner in actual implementation; for example, a plurality of units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the displayed or discussed mutual couplings or direct couplings or communication connections between different units, or the among different units, can be indirect couplings or communication connections through some interfaces, devices or units, and can be in electrical, mechanical or other forms.

[0059] The units described as separated components can or can not be physically separated, and the components displayed as units can or can not be physical units; they can be located in one position, or can be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purposes of the embodiments of the present application.

[0060] In addition, each functional unit in the various embodiments of the present application can be integrated in one processing unit, or each unit can exist physically, or two or more units can be integrated in one unit. The integrated unit can be in the form of hardware, or in the form of software functional units.

[0061] Those skilled in the art should understand that the above-mentioned specific embodiments are only examples and are not limiting, and the embodiments of the present application can be variously modified, combined, partially combined and replaced according to design requirements and other factors, as long as they are within the scope of the appended claims or their equivalents, which belong to the scope of protection of the present application.

Claims

1. A circuit for coil break detection, characterized in that, The circuit comprises: a filtering module configured to receive a voltage signal associated with the coil and output a filtered voltage signal to a comparator; a threshold setting module configured to output a threshold signal to the comparator; the comparator comprising a positive phase input end, a negative phase output end and an output end, the positive phase input end being connected to the filtering module to receive the filtered voltage signal, the negative phase output end being connected to the threshold setting module to receive the threshold signal, and the output end outputting an output signal generated based on comparison of the filtered voltage signal and the threshold signal; a biasing module connected between the positive phase input end and the output end of the comparator; and a processing module configured to receive the output signal of the comparator and determine whether the coil is disconnected based on whether a rising edge and a falling edge of the output signal are detected.

2. The circuit of claim 1, wherein, The filtering module comprises an input end, an output end, a first resistor and a first capacitor, wherein a first end of the first resistor is connected to the input end of the filtering module and a second end is connected to the output end of the filtering module, and a first end of the first capacitor is grounded and a second end is connected to the output end of the filtering module.

3. The circuit of claim 1, wherein, The threshold setting module comprises a second resistor, a third resistor, a second capacitor and an output end, wherein a first end of the second resistor is connected to a power supply and a second end is connected to the output end of the threshold setting module, a first end of the third resistor is grounded and a second end is connected to the output end of the threshold setting module, and the second capacitor is connected in parallel across the third resistor.

4. The circuit of claim 3, wherein, The second resistor and the third resistor are pre-set such that a voltage value of the threshold signal is between 0 volts and 0.8 volts.

5. The circuit of claim 1, wherein, The biasing module comprises a fourth resistor and a fifth resistor, wherein a first end of the fourth resistor is connected to the power supply and a second end is connected to the positive phase input end of the comparator, and a first end of the fifth resistor is connected to the positive phase input end of the comparator and a second end is connected to the output end of the comparator.

6. The circuit of claim 1, wherein, The processing module is configured to: determine that the coil is connected based on that a rising edge and a falling edge of the output signal are detected within a detection period; and determine that the coil is disconnected based on that a rising edge or a falling edge of the output signal is not detected within the detection period.

7. The circuit of claim 6, wherein, The detection period is 20 milliseconds.

8. The circuit of claim 1, wherein, The circuit further comprises: an enabling module connected between the processing module and the output end of the threshold setting module and configured to receive a detection enabling signal from the processing module; and a level conversion module connected between the output end of the comparator and the processing module and configured to receive the output signal from the comparator and output a converted output signal to the processing module.

9. The circuit of claim 8, wherein, The enabling module comprises an input end, a sixth resistor and a transistor, wherein a first end of the sixth resistor is connected to the input end of the enabling module and a second end is connected to a base of the transistor, an emitter of the transistor is grounded and a collector is connected to the output end of the threshold setting module.

10. The circuit of claim 8, wherein, The level conversion module comprises an input end, a diode, a seventh resistor, an eighth resistor, a third capacitor and an output end, wherein the first end of the diode is connected to the input end and the second end is connected to the first end of the seventh resistor, the second end of the seventh resistor is connected to the output end of the level conversion module, the first end of the eighth resistor is connected to a power supply and the second end is connected to the output end of the level conversion module, the first end of the third capacitor is grounded and the second end is connected to the output end of the level conversion module.

11. The circuit of claim 8, wherein, The processing module is further configured to: determine that the coil is broken based on the converted output signal being a high level signal greater than a first threshold voltage.

12. A circuit breaker characterized by, The circuit breaker comprises the circuit as claimed in any one of claims 1-11.

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