CN112068040A

CN112068040A - Connection detection circuit and method and electric equipment

Info

Publication number: CN112068040A
Application number: CN202010962388.9A
Authority: CN
Inventors: 胡江; 沈丽凤; 钱沛; 周葆林
Original assignee: Gree Electric Appliances Inc of Zhuhai
Current assignee: Gree Electric Appliances Inc of Zhuhai
Priority date: 2020-09-14
Filing date: 2020-09-14
Publication date: 2020-12-11

Abstract

The invention discloses a connection detection circuit, a connection detection method and electric equipment. Wherein, this circuit includes: the input end of the first detection module is connected between the first terminal and the third terminal of the electric equipment, and the output end of the first detection module is connected with the logic operation module; the input end of the second detection module is connected between the second terminal and the third terminal of the electric equipment, and the output end of the second detection module is connected with the logic operation module; the logic operation module is used for generating PWM signals according to the signals output by the first detection module and the second detection module; and the judging module is used for judging whether the connection relation of the electric equipment is abnormal or not according to the duty ratio of the PWM signal. According to the invention, the influence of voltage fluctuation on the judgment result can be avoided, the detection accuracy is improved, and meanwhile, whether the connection relation is abnormal or not can be judged through a single period, so that real-time detection is realized.

Description

Connection detection circuit and method and electric equipment

Technical Field

The invention relates to the technical field of electronic circuits, in particular to a connection detection circuit, a connection detection method and electric equipment.

Background

In refrigeration electric equipment and devices using three-phase electricity, in a load loop powered by an alternating current power supply, if a certain phase of the electric equipment is connected to a zero line in a wrong way or a certain phase is not connected, the load can not work normally, so that whether the input connection relation of the alternating current power supply is normal or not needs to be detected by protecting the electric equipment at the front end of the power supply, for example, if only three live wires A/B/C are needed to be connected in practical engineering, if one of the live wires is connected to a zero line N, a fault needs to be reported at this time, and a load loop at the rear stage is cut off at the same time; if the three phases of the alternating current power supply have the condition of phase loss, a fault is also reported, and a load loop at the rear stage is cut off simultaneously to protect load electric equipment and ensure the electric safety.

At present, the faults are processed by acquiring an AD value of alternating current AC/BC at a zero crossing point through a main chip, so that whether the connection relation is abnormal or not is judged, and on one hand, the detected zero crossing point fluctuates when an alternating current power supply fluctuates, so that the detection is inaccurate; on the other hand, the detection method can find the zero crossing point only by selecting a plurality of cycles, and cannot detect and judge in real time.

Aiming at the problems of inaccurate connection detection and incapability of real-time detection in the prior art, an effective solution is not provided at present.

Disclosure of Invention

The embodiment of the invention provides a connection detection circuit, a connection detection method and electric equipment, and aims to solve the problems that connection detection is inaccurate and real-time detection cannot be realized in the prior art.

In order to solve the above technical problem, the present invention provides a connection detection circuit, wherein the circuit includes:

the input end of the first detection module is connected between the first terminal and the third terminal of the electric equipment, and the output end of the first detection module is connected with the logic operation module;

the input end of the second detection module is connected between the second terminal and the third terminal of the electric equipment, and the output end of the second detection module is connected with the logic operation module;

the logic operation module is used for generating PWM signals according to the signals output by the first detection module and the second detection module;

and the judging module is used for judging whether the connection relation of the electric equipment is abnormal or not according to the duty ratio of the PWM signal.

Further, the logic operation module includes an exclusive or gate chip, and the exclusive or gate chip is configured to output a low level when the signals output by the first detection module and the second detection module are the same; and when the signals output by the first detection module and the second detection module are opposite, outputting a high level.

Further, the determining module is specifically configured to determine whether a duty ratio of the PWM signal is within a first preset range; when the duty ratio is within a first preset range, judging that the connection relation of the electric equipment is normal; and when the duty ratio is not in a first preset range, judging that the connection relation of the electric equipment is abnormal.

Furthermore, the first detection module comprises a first comparison unit, an input end of the first comparison unit is connected between a first terminal and a third terminal of the electric device, and an output end of the first comparison unit is connected with the logic operation module;

the second detection module comprises a second comparison unit, the input end of the second comparison unit is connected between the second terminal and the third terminal of the electric equipment, and the output end of the second comparison unit is connected with the logic operation module.

Further, the first comparing unit includes: the output end of the first comparator is connected with the logic operation module;

the second comparing unit, wherein: the inverting input end of the second comparator is connected with the second reference voltage source, the non-inverting input end of the second comparator is connected with the second terminal of the electric equipment, and the output end of the second comparator is connected with the logic operation module.

Further, the first reference voltage source includes: the circuit comprises a first voltage source, a first resistor and a second resistor, wherein the first resistor and the second resistor are connected in series and then are connected with the first voltage source, a line led out between the first resistor and the second resistor is connected with the inverting input end of a first comparator, the positive electrode of a power supply of the first comparator is connected with the first voltage source, and the negative electrode of the power supply is connected with a reference ground;

the second reference voltage source, comprising: the circuit that draws between third resistance and the fourth resistance is connected the inverting input end of second comparator, the power positive pole of second comparator is connected the second voltage source, and the power negative pole is connected reference ground.

Further, the first detection module further includes: the input end of the first operational amplifier unit is connected between the first terminal and the third terminal of the electric equipment, the output end of the first operational amplifier unit is connected with the first comparison unit, and the first operational amplifier unit is used for reducing the voltage between the first terminal and the third terminal of the electric equipment and then outputting the voltage to the first comparison unit;

the second detection module further comprises: and the input end of the second operational amplifier unit is connected between the second terminal and the third terminal of the electric equipment, the output end of the second operational amplifier unit is connected with the second comparison unit, and the second operational amplifier unit is used for reducing the voltage between the second terminal and the third terminal of the electric equipment and then outputting the voltage to the second comparison unit.

Further, the first operational amplifier unit comprises: the non-inverting input end of the first operational amplifier is connected to the first terminal of the electric device, the inverting input end of the first operational amplifier is connected to the output end of the first operational amplifier, the positive power supply electrode of the first operational amplifier is connected to a third voltage source, the negative power supply electrode of the first operational amplifier is connected to the reference ground, and the third terminal of the electric device is connected between the negative power supply electrode of the first operational amplifier unit and the reference ground;

the second operational amplifier unit comprises: the non-inverting input end of the second operational amplifier is connected to the second terminal of the electric device, the inverting input end of the second operational amplifier is connected to the output end of the second operational amplifier, the positive power supply electrode of the second operational amplifier is connected to the fourth voltage source, the negative power supply electrode of the second operational amplifier is connected to the reference ground, and the third terminal of the electric device is connected between the negative power supply electrode of the first operational amplifier unit and the reference ground.

Further, the first operational amplifier unit further includes: a fifth resistor, a sixth resistor, a seventh resistor and an eighth resistor; the fifth resistor is connected between the non-inverting input end of the first operational amplifier and the first terminal of the electric equipment, one end of the sixth resistor is connected between the fifth resistor and the non-inverting input end of the first operational amplifier, the other end of the sixth resistor is connected with a fifth voltage source, the seventh resistor is connected between the output end and the inverting input end of the first operational amplifier unit, and the eighth resistor is connected between the output end of the first operational amplifier unit and the reference ground;

the second operational amplifier unit further comprises: a ninth resistor, a tenth resistor, an eleventh resistor, and a twelfth resistor; the ninth resistor is connected between the non-inverting input end of the second operational amplifier and the second terminal of the power consumption device, one end of the tenth resistor is connected between the ninth resistor and the non-inverting input end of the second operational amplifier, the other end of the tenth resistor is connected with a sixth voltage source, the eleventh resistor is connected between the output end and the inverting input end of the second operational amplifier unit, and the twelfth resistor is connected between the output end of the second operational amplifier unit and the reference ground.

Further, the circuit further comprises: one end of the thirteenth resistor is connected between the first detection module and the logic operation module, and the other end of the thirteenth resistor is connected with a reference ground;

and one end of the fourteenth resistor is connected between the second detection module and the logic operation module, and the other end of the fourteenth resistor is connected with a reference ground.

The invention also provides electric equipment which comprises the connection detection circuit.

Further, the electric equipment comprises at least one of the following: air conditioner, washing machine, refrigerator, water heater, fan, drying-machine, air purifier, water purification machine.

The invention also provides a connection detection method, which is applied to the connection detection circuit and comprises the following steps:

calculating the duty ratio of the PWM signal; the PWM signal is generated according to signals output by the first detection module and the second detection module;

and judging whether the connection relation of the electric equipment is abnormal or not according to the duty ratio.

Further, judging whether the connection relation of the electric equipment is abnormal according to the duty ratio comprises:

judging whether the duty ratio is within a first preset range;

if so, judging that the connection relation of the electric equipment is normal;

and if not, judging that the connection relation of the electric equipment is abnormal.

Further, after determining that the connection relationship of the electric device is abnormal, the method further includes:

continuously judging the range of the duty ratio;

and determining the type of the abnormity according to the range of the duty ratio.

Further, determining the type of the abnormality according to the range of the duty ratio includes:

if the duty ratio is in a second preset range, determining that the abnormal type of the power interface is a first type of abnormality or a second type of abnormality;

if the duty ratio is in a third preset range, determining that the abnormal type of the power interface is a third type of abnormality;

and if the duty ratio is in a fourth preset range, determining that the type of the abnormality of the power interface is a fourth type of abnormality.

The present invention also provides a computer-readable storage medium having stored thereon a computer program which, when executed by a processor, implements the above-described connection detection method.

By applying the technical scheme of the invention, the electric signals between the first terminal and the third terminal of the electric equipment and between the second terminal and the third terminal are detected and passed through the logic operation module; generating a PWM signal according to signals output by the first detection module and the second detection module; and then, the judgment module judges whether the connection relation of the electric equipment is abnormal according to the duty ratio of the PWM signal, so that the influence of voltage fluctuation on a judgment result can be avoided, the detection accuracy is improved, and meanwhile, whether the connection relation is abnormal can be judged through a single period, so that the real-time detection is realized.

Drawings

FIG. 1 is a block diagram of a connection detection circuit according to an embodiment of the present invention;

FIG. 2 is a waveform diagram of an output signal of a first detection module according to an embodiment of the invention;

FIG. 3 is a waveform diagram of an output signal of a second detection module according to an embodiment of the invention;

FIG. 4 is a waveform diagram of a PWM signal in a normal state according to an embodiment of the present invention;

FIG. 5 is a block diagram of a connection detection circuit according to another embodiment of the present invention;

FIG. 6 is a waveform diagram of a PWM signal in a first type abnormal state according to an embodiment of the present invention;

FIG. 7 is a waveform diagram of a PWM signal under a second type of abnormal condition in accordance with an embodiment of the present invention;

FIG. 8 is a waveform diagram of a PWM signal under a third type of abnormal condition in accordance with an embodiment of the present invention;

FIG. 9 is a waveform diagram of a PWM signal in a fourth type of abnormal state in accordance with an embodiment of the present invention;

FIG. 10 is a block diagram of a connection detection circuit according to another embodiment of the present invention;

fig. 11 is a flowchart of a connection detection method according to an embodiment of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention clearer, the present invention will be described in further detail with reference to the accompanying drawings, and it is apparent that the described embodiments are only a part of the embodiments of the present invention, not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The terminology used in the embodiments of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used in the examples of the present invention and the appended claims, the singular forms "a", "an", and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise, and "a plurality" typically includes at least two.

It should be understood that the term "and/or" as used herein is merely one type of association that describes an associated object, meaning that three relationships may exist, e.g., a and/or B may mean: a exists alone, A and B exist simultaneously, and B exists alone. In addition, the character "/" herein generally indicates that the former and latter related objects are in an "or" relationship.

It should be understood that although the terms first, second, etc. may be used to describe the detection modules in embodiments of the present invention, these detection modules should not be limited to these terms. These terms are only used to distinguish between different detection modules. For example, a first detection module may also be referred to as a second detection module, and similarly, a second detection module may also be referred to as a first detection module without departing from the scope of embodiments of the present invention.

The words "if", as used herein, may be interpreted as "at … …" or "at … …" or "in response to a determination" or "in response to a detection", depending on the context. Similarly, the phrases "if determined" or "if detected (a stated condition or event)" may be interpreted as "when determined" or "in response to a determination" or "when detected (a stated condition or event)" or "in response to a detection (a stated condition or event)", depending on the context.

It is also noted that the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that an article or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such article or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other like elements in the article or device in which the element is included.

Alternative embodiments of the present invention are described in detail below with reference to the accompanying drawings.

Example 1

This embodiment provides a connection detection circuit, and fig. 1 is a structural diagram of a connection detection circuit according to an embodiment of the present invention, as shown in fig. 1, the connection detection circuit includes:

the input end of the first detection module 10 is connected between a first terminal A and a third terminal C of the electric equipment, and the output end of the first detection module 10 is connected with the logic operation module; the input end of the second detection module 20 is connected between the second terminal B and the third terminal C of the electric device, and the output end of the second detection module 20 is also connected with the logic operation module; the first terminal A, the second terminal B and the third terminal C are respectively used for connecting three live wires L1, L2 and L3 of a power supply system; a logic operation module 30, configured to generate a PWM signal according to the signals output by the first detection module 10 and the second detection module 20; and the judging module 40 is configured to judge whether the connection relationship of the electrical equipment is abnormal according to the duty ratio of the PWM signal.

In the present embodiment, the input terminal of the first detection module 10 is connected between the first terminal a and the third terminal C of the electric device, and the input terminal of the second detection module 20 is connected between the second terminal B and the third terminal C of the electric device, but in other embodiments of the present invention, the input terminal of the first detection module 10 may be connected between the first terminal a and the second terminal B of the electric device, and the input terminal of the second detection module 20 may be connected between the second terminal B and the third terminal C of the electric device, or the input terminal of the first detection module 10 may be connected between the first terminal a and the second terminal B of the electric device, and the input terminal of the second detection module 20 may be connected between the first terminal a and the third terminal C of the electric device.

Fig. 2 is a waveform diagram of an output signal of the first detection module according to an embodiment of the present invention, as shown in fig. 2, a cosine signal between the first terminal a and the third terminal C is converted into a square wave signal by the first detection module 10 and then output, that is, an output signal at a point b of a sampling point at an output end of the first detection module 10 is a high-low level signal that repeats periodically.

Fig. 3 is a waveform diagram of an output signal of the second detection module according to the embodiment of the invention, as shown in fig. 3, a cosine signal between the second terminal B and the third terminal C is converted into a square wave signal by the second detection module 20 and then output, that is, an output signal at a point a of a sampling point at an output end of the second detection module 20 is a high-low level signal which is periodically repeated.

Fig. 4 is a waveform diagram of a PWM signal in a normal state according to an embodiment of the present invention, as shown in fig. 4, where the connections are correct at the terminals of the electric device, that is, when the connection is normal, the phase difference between the cosine signal between the second terminal B and the third terminal C and the cosine signal between the first terminal A and the third terminal C is 60 degrees, i.e., the time difference (1/3) T, where T is the half period of the cosine signal, and thus, as shown in fig. 4, the waveform pattern of the output signal of the first detection module 10 is staggered from the waveform of the output signal of the second detection module 20 by the time difference (1/3) T, after obtaining the output signals of the first detection module 10 and the second detection module 20, the logic operation module 30, the PWM signal, i.e., the output signal of the c point of the sampling point, is generated according to the signals output by the first detection module 10 and the second detection module 20. At this time, the duty ratio of the output signal is a constant value, and if the connection relationship is abnormal, that is, if the terminals of the electric equipment are connected incorrectly, the phase difference between the output signal waveform at the point b and the output signal at the point a changes, the waveform generating the PWM signal also changes, and the duty ratio of the PWM signal changes.

The connection detection circuit of the embodiment detects electrical signals between a first terminal and a third terminal of the electric equipment and between a second terminal and the third terminal through at least two detection modules, and passes through a logic operation module; generating a PWM signal according to signals output by the first detection module and the second detection module; and then, the judgment module judges whether the connection relation of the electric equipment is abnormal according to the duty ratio of the PWM signal, so that the influence of voltage fluctuation on a judgment result can be avoided, the detection accuracy is improved, and meanwhile, whether the connection relation is abnormal can be judged through a single period, so that the real-time detection is realized.

Example 2

In this embodiment, another connection detection circuit is provided, and fig. 5 is a structural diagram of a connection detection circuit according to another embodiment of the present invention, as shown in fig. 5, the logic operation module 30 includes:

an exclusive or gate chip IC1, the exclusive or gate chip IC1 is configured to output a low level when the signals output by the first detection module 10 and the second detection module 20 are the same; when the signals output by the first detection module 10 and the second detection module 20 are opposite, a high level is output. The judging module 40 is specifically configured to judge whether the duty ratio of the PWM signal is within a first preset range; when the duty ratio is within a first preset range, judging that the connection relation of the electric equipment is normal; and when the duty ratio is not in a first preset range, judging that the connection relation of the electric equipment is abnormal.

For example, when the connection is correct at each terminal of the electric device, that is, the first terminal a of the electric device is connected to the first live line L1 of the power supply system, the second terminal B of the electric device is connected to the second live line L2 of the power supply system, and the third terminal C of the electric device is connected to the third live line L3 of the power supply system, the connection relationship is normal, the phase difference between the cosine signal between the second terminal B and the third terminal C and the cosine signal between the first terminal a and the third terminal C is 60 °, that is, the time difference is (1/3) T, where T is a half period, and therefore, the time difference between the waveform diagram of the output signal at the point a and the waveform of the output signal at the point B is (1/3) T, and after the output signals of the first detection module 10 and the second detection module 20 are obtained, the xor gate chip IC1 outputs the same signals from the first detection module 10 and the second detection module 20, that is, when both output low level, or both output high level, output low level; when the signals output by the first detection module 10 and the second detection module 20 are opposite, that is, one of the first detection module 10 and the second detection module 20 outputs a low level, and the other outputs a high level, a high level is output. According to fig. 4 above, when the time difference between the waveform diagram of the output signal of the first detection module 10 and the waveform of the output signal of the second detection module 20 is (1/3) T, in one period, the ratio of the time of outputting the low level by one of the first detection module 10 and the second detection module 20 and the high level by the other one is 1/3, that is, the total time of the high level signal outputted from the xor gate chip IC1 in one period is 1/3 of the period length, that is, the duty ratio of the PWM signal outputted at point c is 1/3, the setting error range is + -3% due to the fluctuation error, the judging module 40 judges whether the duty ratio of the PWM signal is in the range of (33.33 + -3)%, if so, indicating that the connection relation of the electric equipment is normal, otherwise, indicating that the connection relation of the electric equipment is abnormal.

When one of the terminals of the electric equipment is incorrectly connected, that is, the connection relationship is abnormal, for example, when the first terminal a of the electric equipment is connected to the zero line N of the power supply system, the phase difference between the cosine signal between the second terminal B and the third terminal C and the cosine signal between the first terminal a and the third terminal C is 30 °, that is, the time difference is (1/6) T, so that the time difference between the waveform diagram of the output signal at the point a and the waveform of the output signal at the point B is (1/6) T, and after the output signals of the first detection module 10 and the second detection module 20 are obtained, the xor gate chip IC1 outputs a low level when both the first detection module 10 and the second detection module 20 output a low level or both output a high level; when one of the first and

second detection modules

10 and 20 outputs a low level and the other outputs a high level, a high level is output.

Fig. 6 is a waveform diagram of the PWM signal in the first type abnormal state according to the embodiment of the present invention, and as shown in fig. 6, when the time difference between the waveform diagram of the output signal of the first detection module 10 and the waveform of the output signal of the second detection module 20 is (1/6) T, in one period, the ratio of the time of outputting the low level from one of the first detection module 10 and the second detection module 20 to the time of outputting the high level from the other to the whole period is 1/6, that is, in one period, the total time of outputting the high level signal from the xor gate chip IC1 to 1/6 of the period length, that is, the duty ratio of the PWM signal output at the c point is 1/6.

When the second terminal B of the electric equipment is connected to the zero line N of the power supply system, the phase difference between the cosine signal between the second terminal B and the third terminal C and the cosine signal between the first terminal a and the third terminal C is 30 °, namely, the time difference is (1/6) T, so that the time difference between the waveform diagram of the output signal of B and the waveform of the output signal at the point a is (1/6) T, after the output signals of the first detection module 10 and the second detection module 20 are obtained, the xor gate chip IC1 outputs a low level when both the first detection module 10 and the second detection module 20 output a low level, or both the first detection module 10 and the second detection module 20 output a high level; when one of the first and

second detection modules

Fig. 7 is a waveform diagram of a PWM signal in a second type abnormal state according to an embodiment of the present invention, and fig. 7 shows that when a time difference between a waveform diagram of an output signal of the first detection module 10 and a waveform of an output signal of the second detection module 20 is (1/6) T, one of the first detection module 10 and the second detection module 20 outputs a low level and the other outputs a high level in a cycle with a ratio of 1/6, that is, the total time of high level signals output by the xor gate chip IC1 in a cycle with a cycle length of 1/6, that is, the duty ratio of the PWM signal output at the c point is 1/6, in the above case, the determination module 40 may determine whether the duty ratio of the PWM signal is in a range of (16.67 ± 3%), if so, it may indicate that the connection relationship of the electric device is abnormal, and the abnormal type is that the first terminal a or the second terminal B of the electric device is mistakenly connected to the zero line of the power supply system And N is added.

For another example, when the third terminal C of the electric device is connected to the zero line N of the power supply system, the phase difference between the cosine signal between the second terminal B and the third terminal C and the cosine signal between the first terminal a and the third terminal C is 120 °, i.e., the time difference is (2/3) T, so that the time difference between the waveform diagram of the output signal at the point a and the waveform of the output signal at the point B is (2/3) T, and after the output signals of the first detection module 10 and the second detection module 20 are obtained, the xor gate chip IC1 outputs a low level when both the first detection module 10 and the second detection module 20 output a high level; when one of the first and

second detection modules

Fig. 8 is a waveform diagram of a PWM signal in a third type abnormal state according to an embodiment of the present invention, and as shown in fig. 8, when a time difference between a waveform diagram of an output signal of the first detection module 10 and a waveform of an output signal of the second detection module 20 is (2/3) T, in a cycle, a ratio of a time of one of the first detection module 10 and the second detection module 20 outputting a low level and a time of the other outputting a high level to the whole cycle is 2/3, that is, in a cycle, a total time of high level signals output by the xor gate chip IC1 to 2/3 of a cycle length, that is, a duty ratio of the PWM signal output at a point c is 2/3, in the above case, the determination module 40 may determine whether the duty ratio of the PWM signal is in a range of (66.67 ± 3%), if so, it may indicate that a connection relationship of the electric device is abnormal, and the abnormal type is that the third terminal C of the electric equipment is misconnected to the zero line N of the power supply system.

For another example, when the second terminal B of the electrical device is in a leakage state, a low level is always output between the second terminal B and the third terminal C at this time, a low level is always output at a point a, and a square wave signal with a duty ratio of 50% is output at a point B, so that in one period, the proportion of the time for one of the first detection module and the second detection module to output a low level and the time for the other to output a high level to the whole period is 1/2, after the output signals of the first detection module 10 and the second detection module 20 are obtained, the xor gate chip IC1 outputs a low level when both the first detection module 10 and the second detection module 20 output a high level; when one of the first and

second detection modules

Fig. 9 is a waveform diagram of a PWM signal in a fourth type abnormal state according to an embodiment of the present invention, as shown in fig. 9, when the point a outputs a low level all the time and the point b outputs a square wave signal with a duty ratio of 50%, in one period, one of the first detection module 10 and the second detection module 20 outputs a low level, and the other outputs a high level for a ratio of 1/2, that is, the total time of the high level signal outputted from the xor gate chip IC1 in one period is 1/2 of the period length, that is, the duty ratio of the PWM signal outputted at point c is 1/2, in the above case, the determination module 40 may determine whether the duty ratio of the PWM signal is in the range of (50 ± 3)%, if yes, the abnormal connection relation of the electric equipment is indicated, and the abnormal type is that the second terminal B of the electric equipment is missed.

As the initial input signal of the electric device is a cosine signal, the cosine signal between the second terminal B and the third terminal C and the cosine signal between the first terminal a and the third terminal C need to be converted into square signals with the same frequency and phase, as shown in fig. 5, the first detection module 10 includes a first comparison unit 101, an input end of the first comparison unit 101 is connected between the first terminal a and the third terminal C of the electric device, and an output end of the first comparison unit 101 is connected to the logic operation module 30; the second detecting module 20 includes a second comparing unit 201, an input end of the second comparing unit 201 is connected between the second terminal B and the third terminal C of the electric device, and an output end of the second comparing unit 201 is connected to the logic operation module 30. The cosine signal between the first terminal a and the third terminal C is converted into a square wave signal with the same frequency and phase by the first comparing unit 101, and the cosine signal between the second terminal B and the third terminal C is converted into a square wave signal with the same frequency and phase by the second comparing unit 201.

Specifically, as shown in fig. 5, the first comparing unit 101 includes: the power supply comprises a first comparator A1 and a first reference voltage source Vref1, wherein the inverting input end IN-of the first comparator A1 is connected with the first reference voltage source Vref1, the non-inverting input end IN + is connected with a first terminal A of the electric equipment, and the output end out of the first comparator A1 is connected with the logic operation module 30; a second comparing unit 201, comprising: the second comparator a2 and a second reference voltage source Vref2, the inverting input terminal IN-of the second comparator a2 is connected to the second reference voltage source Vref2, the non-inverting input terminal IN + is connected to the second terminal of the electric device, and the output terminal out of the second comparator a2 is connected to the logic operation module 30.

In order to obtain the required reference voltage, the first reference voltage source Vref1 can be obtained by voltage division, as shown in fig. 5, the first reference voltage source Vref1 includes: the circuit comprises a first voltage source VCC1, a first resistor R1 and a second resistor R2, wherein the first resistor R1 is connected with the second resistor R2 IN series and then is connected with a first voltage source VCC1, a first reference voltage is output between the first resistor R1 and the second resistor R2, the first reference voltage is input into an inverting input end IN of a first comparator A1, a power supply anode VS + of the first comparator A1 is also connected with the first voltage source VCC1, and a power supply cathode VS-is connected with a reference ground; the second reference voltage source Vref2 includes: the circuit comprises a second voltage source VCC2, a third resistor R3 and a fourth resistor R4, wherein the third resistor R3 is connected with the fourth resistor R4 IN series and then is connected with the second voltage source VCC2, a second reference voltage is output between the third resistor R3 and the fourth resistor R4, the second reference voltage is input into the inverting input end IN of a second comparator A2, the power supply anode VS + of the second comparator A2 is also connected with the second voltage source VCC2, and the power supply cathode VS-is connected with the reference ground.

Since the initial input signal of the electric device is a strong electric signal with a high amplitude, and the comparator and other elements need to operate under a weak electric current, as shown in fig. 5, the first detecting module 10 further includes: the input end of the first operational amplifier unit 102 is connected between a first terminal a and a third terminal C of the electric equipment, the output end of the first operational amplifier unit 102 is connected with the first comparison unit 101, and the first operational amplifier unit 102 is used for reducing the voltage between the first terminal a and the third terminal C of the electric equipment and then outputting the voltage to the first comparison unit 101; specifically, the first operational amplifier unit 102 includes: the first operational amplifier U1 has a non-inverting input terminal IN + connected to the first terminal a of the power device, an inverting input terminal connected to the output terminal out thereof, an output terminal out connected to the non-inverting input terminal IN + of the first comparator a1, a positive power source VS + connected to the third voltage source VSs1, a negative power source VS-connected to the ground, and a third terminal C connected between the negative power source VS-of the first operational amplifier unit 102 and the ground.

Similarly, the second detection module 20 further includes: and an input end of the second operational amplifier unit 202 is connected between the second terminal B and the third terminal C of the electric device, an output end of the second operational amplifier unit 202 is connected to the second comparing unit 201, and the second operational amplifier unit is used for reducing the voltage between the second terminal B and the third terminal C of the electric device and then outputting the voltage to the second comparing unit 201. Specifically, the second operational amplifier unit 202 includes: the non-inverting input terminal IN + of the second operational amplifier U2 is connected to the second terminal B of the power-consuming device, the inverting input terminal thereof is connected to the output terminal out thereof, the output terminal out thereof is also connected to the non-inverting input terminal IN + of the second comparator a2, the positive power supply terminal VS + thereof is connected to the fourth voltage source VSs2, the negative power supply terminal VS-thereof is connected to the reference ground, and the third terminal C of the power-consuming device is connected between the negative power supply terminal VS-of the first operational amplifier unit U1 and the reference ground.

Because the operational amplifier and the input current of the comparator have the maximum limit, in order to avoid the current in the circuit being too large and causing the above-mentioned elements to work normally, it is necessary to limit the current, in order to realize the purpose of limiting the current, the above-mentioned first operational amplifier unit 102, wherein also includes: a fifth resistor R5, a fifth resistor R5 is connected between the non-inverting input IN + of the first operational amplifier U1 and the first terminal a of the powered device for limiting the input current of the first operational amplifier U1.

Meanwhile, in order to implement the voltage division function, as shown in fig. 5, the first operational amplifier unit 102 further includes a sixth resistor R6, a seventh resistor R7, and an eighth resistor R8; one end of the sixth resistor R6 is connected between the fifth resistor R5 and the non-inverting input terminal IN + of the first operational amplifier U1, the other end is connected to the fifth voltage source VDD1 for controlling the input voltage of the non-inverting input terminal IN + of the first operational amplifier U1, the seventh resistor R7 is connected between the output terminal of the first operational amplifier unit 102 and the inverting input terminal IN-for controlling the voltage of the inverting input terminal IN-of the first operational amplifier U1, and the eighth resistor R8 is connected between the output terminal out of the first operational amplifier U1 and the reference ground for controlling the voltage of the output terminal of the first operational amplifier U1.

Similarly, the second operational amplifier unit 202 further includes: a ninth resistor R9, a tenth resistor R10, an eleventh resistor R11, and a twelfth resistor R12; the ninth resistor R9 is connected between the non-inverting input terminal IN + of the second operational amplifier U2 and the second terminal B of the electric device, one end of the tenth resistor R10 is connected between the ninth resistor R9 and the non-inverting input terminal IN + of the second operational amplifier U2, the other end is connected to the sixth voltage source VDD2, the eleventh resistor R11 is connected between the output terminal of the second operational amplifier U2 and the inverting input terminal IN-, and the twelfth resistor R12 is connected between the output terminal out of the second operational amplifier U2 and the reference ground.

In order to limit the input voltage of the xor gate chip IC1, as shown in fig. 5, the circuit further includes: a thirteenth resistor R13, wherein one end of the thirteenth resistor R13 is connected between the first detection module 10 and the logic operation module, and the other end is connected to the reference ground; a fourteenth resistor R14, wherein one end of the fourteenth resistor R14 is connected between the second detecting module 20 and the logic operation module, and the other end is connected to the ground.

Example 3

Fig. 10 is a structural diagram of a connection detecting circuit according to another embodiment of the present invention, and as shown in fig. 10, in this embodiment, resistances of a first resistor R1, a second resistor R2, a third resistor R3, and a fourth resistor R4 are 500 Ω, resistances of a fifth resistor R5 and a ninth resistor R9 are 1M Ω, resistances of a sixth resistor R6 and a tenth resistor R10 are 2.4k Ω, and resistances of a seventh resistor R7, an eighth resistor R8, an eleventh resistor R11, a twelfth resistor R12, a thirteenth resistor R13, and a fourteenth resistor R14 are all 10k Ω.

The models of the first comparator A1 and the second comparator A2 are both LMC7211BIM5, the models of the first operational amplifier U1 and the second operational amplifier U2 are both LM258AD, the model of the XOR gate chip IC1 is 74LS86N, and the voltage provided by the first voltage source VCC1 and the second voltage source VCC2 is 5V; the third voltage source VSS1 and the fourth voltage source VSS2 provide 12V, and the fifth voltage source VDD1 and the sixth voltage source VDD2 provide 2.2V. The input signal Vin and the output signal Vout of the first operational amplifier satisfy the following relationship:

namely, it is

Vout＝2.494+0.9098cos(wt)

Where w is the phase angle change speed and t is time. Similarly, the input signal Vin and the output signal Vout of the first operational amplifier satisfy the following relationship:

the embodiment provides a circuit for judging abnormal connection relation by using duty ratio, based on the principle that the phase difference of three-phase voltage input by electric equipment corresponds to the duty ratio of a finally generated PWM detection signal, when the wiring of an input signal is normal, the duty ratio is a fixed value (33.33 +/-3)% (considering that power supply fluctuates under different environments, the error range is +/-3%), and when the wiring of the input signal is wrong, the duty ratio of the detection signal is changed, so that the fault detection of the input signal of the three-phase power supply is realized.

By the connection detection circuit of the embodiment, the following technical effects can be obtained:

1. the zero-crossing detection method of the alternating current signal is avoided, and the problem of inaccurate detection caused by alternating current power supply fluctuation is solved;

2. multiple periods are not needed to find the zero crossing point, whether the connection relation is abnormal or not can be judged in each period, and the real-time performance is higher;

3. the corresponding relation between the phase difference and the duty ratio is provided, and whether the current connection relation is abnormal or not is more intuitively and conveniently identified.

Example 4

This embodiment provides a connection detection method applied to the connection detection circuit in the above embodiment, and fig. 11 is a flowchart of the connection detection method according to the embodiment of the present invention, as shown in fig. 11, the method includes:

s101, calculating the duty ratio of a PWM signal; the PWM signal is generated according to signals output by the first detection module and the second detection module.

Through a first detection module and a second detection module, cosine wave signals input between a first phase and a third phase of the electric equipment and between a second phase and the third phase are converted into two square wave signals respectively, through a logic operation module, PWM signals are generated based on the two square wave signals, and the duty ratio of the generated PWM signals can be obtained through calculation.

And S102, judging whether the connection relation of the electric equipment is abnormal or not according to the duty ratio of the PWM signal.

When the terminals of the electric equipment are correctly connected, namely the connection relation is normal, because the phase difference between the cosine signal between the second terminal and the third terminal and the cosine signal between the first terminal and the third terminal is 60 degrees, namely the time difference is (1/3) T, wherein T is a half period of the signal, as shown in the above mentioned figure 4, the waveform diagram of the output signal of the first detection module is staggered with the waveform of the output signal of the second detection module, and after the output signals of the first detection module and the second detection module are obtained, the logic operation module generates a PWM signal according to the signals output by the first detection module and the second detection module. At this time, the duty ratio of the output signal is a constant value, and if one of the terminals of the electric device is connected incorrectly, that is, if the connection relationship is abnormal, the phase difference between the output signal waveform at the point b and the output signal at the point a changes, which causes the waveform of the generated PWM signal to change, and further causes the duty ratio of the PWM signal to change.

According to the connection detection method, whether the connection relation of the electric equipment is abnormal or not is judged according to the duty ratio of the PWM signals generated by the signals output by the first detection module and the second detection module, the influence of voltage fluctuation on the judgment result can be avoided, the detection accuracy is improved, meanwhile, whether the connection relation is abnormal or not can be judged through a single period, and real-time detection is achieved.

As described above, when the connection is correct at each terminal of the electric device, that is, the first terminal a of the electric device is connected to the first live line L1 of the power supply system, the second terminal B of the electric device is connected to the second live line L2 of the power supply system, and the third terminal C of the electric device is connected to the third live line L3 of the power supply system, the connection relationship is normal, and at this time, the phase difference between the cosine signal between the second terminal B and the third terminal C and the cosine signal between the first terminal a and the third terminal C is 60 °, that is, the phase difference is (1/3) T, where T is a half period, so that the time difference between the waveform diagram of the output signal at the point a and the waveform of the output signal at the point B is (1/3) T, and in one period, the time of one of the first detection module and the second detection module outputting the low level and the time of the other outputting the high level accounts for 1/3 of the entire period, that is, in one period, the total time of the high level signal output by the xor gate chip IC1 occupies 1/3 of the period length, that is, the duty ratio of the output PWM signal is 1/3, and due to the fluctuation error, it is determined whether the duty ratio of the PWM signal is within the range of (33.3 ± 3)%, if so, it is indicated that the connection relationship of the electric equipment is normal, otherwise, it is indicated that the connection relationship of the electric equipment is abnormal. Therefore, in this embodiment, determining whether the connection relationship of the electric device is abnormal according to the duty ratio includes: judging whether the duty ratio is within a first preset range; wherein the first preset range is [ 30.33%, 36.33% ]; if so, judging that the connection relation of the electric equipment is normal; and if not, judging that the connection relation of the electric equipment is abnormal.

When it is determined that the duty ratio of the PWM signal is not within the range of (33.33 ± 3)% it may be determined that the connection relationship is abnormal, but it is not possible to determine which type of abnormality is specific, and therefore, after it is determined that the connection relationship of the electric device is abnormal, the method further includes: continuously judging the range of the duty ratio; and determining the type of the abnormity according to the range of the duty ratio.

According to the above, when one of the terminals of the electric device is incorrectly connected, that is, the connection relationship is abnormal, for example, when the first terminal a of the electric device is connected to the zero line N of the power supply system, the phase difference between the cosine signal between the second terminal B and the third terminal C and the cosine signal between the first terminal a and the third terminal C is 30 °, that is, the time difference (1/6) T, in one cycle, one of the first detection module and the second detection module outputs the low level, the proportion of the time of the other one outputs the high level to the whole cycle is 1/6, that is, in one cycle, the total time of the high level signals output by the xor gate chip IC1 accounts for 1/6 of the cycle length, that is, the duty ratio of the PWM signal output at the point C is 1/6; or, when the second terminal B of the electric device is connected to the zero line N of the power supply system, at this time, the phase difference between the cosine signal between the second terminal B and the third terminal C and the cosine signal between the first terminal a and the third terminal C is 30 °, that is, the time difference (1/6) T, in a period, the proportion of the time of outputting the low level by one of the first detection module and the second detection module to the whole period is 1/6, that is, in a period, the total time of the high level signals output by the xor gate chip IC1 accounts for 1/6 of the period length, that is, the duty ratio of the PWM signal output at the point C is 1/6, in the above case, the judging module 40 can judge whether the duty ratio of the PWM signal is in the range of (16.67 ± 3)%, if so, it indicates that the connection relationship of the electric device is abnormal, and the abnormal type is that the first terminal A or the second terminal B of the electric equipment is misconnected to the zero line N of the power supply system.

For another example, when the third terminal C of the electric device is connected to the zero line N of the power supply system, at this time, the phase difference between the cosine signal between the second terminal B and the third terminal C and the cosine signal between the first terminal a and the third terminal C is 120 °, that is, the time difference is (2/3) T, so that, in one period, the ratio of the time of outputting the low level by one of the first detection module and the second detection module to the whole period is 2/3, that is, in one period, the total time of the high level signals output by the xor gate chip IC1 accounts for 2/3 of the period length, that is, the duty ratio of the PWM signal output at the point C is 2/3, in the above case, it can be determined whether the duty ratio of the PWM signal is within the range of (66.67 ± 3%), if so, it is determined that the connection relationship of the electric device is abnormal, and the abnormal type is that the third terminal C of the electric equipment is misconnected to the zero line N of the power supply system.

For another example, when the second terminal B of the electric device is connected to a drain, a low level is always output between the second terminal B and the third terminal C, a low level is always output at point a, a square wave signal with a duty ratio of 50% is output at point B, in one period, one of the first detection module and the second detection module outputs low level, the other outputs high level in proportion to 1/2 of the whole period, that is, the total time of the high level signal outputted from the xor gate chip IC1 in one period is 1/2 of the period length, that is, the duty ratio of the PWM signal outputted at point c is 1/2, in the above case, it is possible to judge whether or not the duty ratio of the PWM signal is in the range of (50 ± 3)%, if yes, the connection relation of the electric equipment is abnormal, and the abnormal type is that the second terminal B of the electric equipment is missed.

In summary, determining the type of the abnormality according to the range of the duty ratio includes: if the duty ratio is in a second preset range, determining that the abnormal type of the power interface is a first type of abnormality or a second type of abnormality; wherein the second preset range is [ 13.67%, 19.73% ], the first type of abnormity is that the first terminal A of the electric equipment is misconnected to the zero line N of the power supply system, and the second type of abnormity is that the second terminal B of the electric equipment is misconnected to the zero line N of the power supply system; if the duty ratio is in a third preset range, determining that the abnormal type of the power interface is a third type of abnormality; wherein the third preset range is [ 63.67%, 69.67% ], and the third type of abnormality is that the third terminal C of the electrical equipment is misconnected to the zero line N of the power supply system; if the duty ratio is in a fourth preset range, it is determined that the type of the abnormality of the power interface is a fourth type of abnormality, where the fourth preset range is [ 47%, 53% ], and the fourth type of abnormality is that the second terminal B of the power consumption device is missed, it should be noted that, in this embodiment, an error range is only ± 3% as an example, and in practical application, a person skilled in the art may set the error range according to actual needs.

Example 5

The present embodiment provides a connection detection method, which is implemented based on the connection detection circuit in the above embodiment, and a PWM signal, that is, an output signal waveform at the point c in fig. 4 is finally generated by a logic operation circuit, where a duty ratio of the square wave corresponds to a phase difference between line voltages of the AC two phases and the BC two phases, and when an input signal is connected incorrectly or not connected, the phase difference between the line voltages of the AC two phases and the BC two phases may change, and a duty ratio of the PWM signal also changes correspondingly, so that it is only necessary to detect the duty ratio of the PWM signal by a main chip, and it can be determined whether a current three-phase electrical connection relationship is abnormal. Table 1 below is a corresponding relationship between the duty ratio of the PWM signal and the connection detection result.

The proposal provides a connection detection method for judging whether the connection relation between the current electric equipment and a three-phase power supply is correct or not by detecting the duty ratio of a PWM square wave, as shown in the table 1;

through an actual three-phase power supply and a circuit simulation result, when three terminals A/B/C of an electric device are just connected to L1, L2 and L3 of a power supply system, namely, the electric device is correctly connected, the duty ratio of an output signal waveform at a point C can be known to be (33.33 +/-3)% (considering that power supply fluctuates under different environments, a set error range is +/-3%), and the fact that the three-phase power is correctly connected is indicated;

the connection relation is judged to be abnormal under the following conditions:

when the duty ratio of the output signal waveform of the point c is detected to be in the range of (16.67 +/-3)%, judging that the terminal A of the electric equipment is mistakenly connected to the zero line N of the power supply system, or judging that the terminal B of the electric equipment is mistakenly connected to the zero line N of the power supply system; when the output signal waveform of the point C is detected to be in the range of (66.67 +/-3)% duty ratio, judging that the terminal C of the electric equipment is mistakenly connected to the zero line N of the power supply system; when the duty ratio of the output signal waveform at the point c is detected to be within (50 +/-3)% range, the leakage of the terminal B of the electric equipment is judged.

In practical application, whether the current connection relation is correctly accessed can be judged by detecting the duty ratio of the waveform obtained after the exclusive-or circuit, when the duty ratio is detected to be out of a normal range, the current wiring condition can be judged to be abnormal, the load of the rear-stage alternating current circuit can be immediately cut off, and then the rear-stage alternating current load circuit can be protected.

According to the method, real-time judgment can be carried out in each period of the alternating current, the problem that the faults are judged in a mode that AD values of three periods need to be collected at present and zero-crossing points are searched in two periods of the three periods is solved, on one hand, a detection mode is simplified, and when the faults occur, the loads of a rear-stage alternating current loop can be detected immediately and cut off rapidly; on the other hand, whether a fault exists can be judged by detecting the duty ratio, and the problem that when the power supply fluctuates greatly, the fluctuation is large when the AD value is collected, and the zero crossing point searched for is inaccurate can be solved.

Example 6

The present embodiment provides an electric device, including the connection detection circuit in the foregoing embodiments, configured to detect a connection relationship between a point device and a power supply system. In this embodiment, the electric device includes at least one of: air conditioner, washing machine, refrigerator, water heater, fan, drying-machine, air purifier, water purification machine.

Example 7

The present embodiment provides a computer-readable storage medium having stored thereon a computer program which, when executed by a processor, implements the above-described connection detection method.

The above-described circuit embodiments are only illustrative, and the units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of the present embodiment.

Through the above description of the embodiments, those skilled in the art will clearly understand that each embodiment can be implemented by software plus a necessary general hardware platform, and certainly can also be implemented by hardware. Based on the understanding, the above technical solutions may be essentially or partially implemented in the form of software products, which may be stored in a computer-readable storage medium, such as ROM/RAM, magnetic disk, optical disk, etc., and include instructions for causing a computer-powered device (which may be a personal computer, a server, or a network-powered device, etc.) to execute the method according to the embodiments or some parts of the embodiments.

Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.

Claims

1. A connection detection circuit, the circuit comprising:

2. The circuit of claim 1,

the logic operation module comprises an exclusive-or gate chip, and the exclusive-or gate chip is used for outputting a low level when the signals output by the first detection module and the second detection module are the same; and when the signals output by the first detection module and the second detection module are opposite, outputting a high level.

3. The circuit of claim 1,

the judging module is specifically used for judging whether the duty ratio of the PWM signal is within a first preset range; when the duty ratio is within a first preset range, judging that the connection relation of the electric equipment is normal; and when the duty ratio is not in a first preset range, judging that the connection relation of the electric equipment is abnormal.

4. The circuit of claim 1,

the first detection module comprises a first comparison unit, the input end of the first comparison unit is connected between the first terminal and the third terminal of the electric equipment, and the output end of the first comparison unit is connected with the logic operation module;

5. The circuit of claim 4,

the first comparison unit comprises: the output end of the first comparator is connected with the logic operation module;

6. The circuit of claim 5,

the first reference voltage source, comprising: the circuit comprises a first voltage source, a first resistor and a second resistor, wherein the first resistor and the second resistor are connected in series and then are connected with the first voltage source, a line led out between the first resistor and the second resistor is connected with the inverting input end of a first comparator, the positive electrode of a power supply of the first comparator is connected with the first voltage source, and the negative electrode of the power supply is connected with a reference ground;

7. The circuit of claim 4,

the first detection module further comprises: the input end of the first operational amplifier unit is connected between the first terminal and the third terminal of the electric equipment, the output end of the first operational amplifier unit is connected with the first comparison unit, and the first operational amplifier unit is used for reducing the voltage between the first terminal and the third terminal of the electric equipment and then outputting the voltage to the first comparison unit;

8. The circuit of claim 7,

the first operational amplifier unit comprises: the non-inverting input end of the first operational amplifier is connected to the first terminal of the electric device, the inverting input end of the first operational amplifier is connected to the output end of the first operational amplifier, the positive power supply electrode of the first operational amplifier is connected to a third voltage source, the negative power supply electrode of the first operational amplifier is connected to the reference ground, and the third terminal of the electric device is connected between the negative power supply electrode of the first operational amplifier unit and the reference ground;

9. The circuit of claim 8,

the first operational amplifier unit further comprises: a fifth resistor, a sixth resistor, a seventh resistor and an eighth resistor; the fifth resistor is connected between the non-inverting input end of the first operational amplifier and the first terminal of the electric equipment, one end of the sixth resistor is connected between the fifth resistor and the non-inverting input end of the first operational amplifier, the other end of the sixth resistor is connected with a fifth voltage source, the seventh resistor is connected between the output end and the inverting input end of the first operational amplifier unit, and the eighth resistor is connected between the output end of the first operational amplifier unit and the reference ground;

10. The circuit of claim 1, further comprising:

one end of the thirteenth resistor is connected between the first detection module and the logic operation module, and the other end of the thirteenth resistor is connected with a reference ground;

11. An electric device characterized by comprising the connection detection circuit according to any one of claims 1 to 10.

12. The powered device of claim 11, wherein the powered device comprises at least one of:

air conditioner, washing machine, refrigerator, water heater, fan, drying-machine, air purifier, water purification machine.

13. A connection detection method applied to the connection detection circuit according to any one of claims 1 to 10, the method comprising:

14. The method of claim 13, wherein determining whether the connection relationship of the powered device is abnormal according to the duty cycle comprises:

judging whether the duty ratio is within a first preset range;

15. The method according to claim 14, wherein after determining that the connection relationship of the electric device is abnormal, the method further comprises:

continuously judging the range of the duty ratio;

16. The method of claim 15, wherein determining the type of anomaly from a range in which the duty cycle is located comprises:

17. A computer-readable storage medium, on which a computer program is stored, which program, when being executed by a processor, carries out the method according to any one of claims 13 to 16.