CN115441401A

CN115441401A - Residual current protection device, working state output method and charging equipment

Info

Publication number: CN115441401A
Application number: CN202211248155.8A
Authority: CN
Inventors: 徐首旗
Original assignee: Shanghai Shengwei Electronic Technology Co ltd
Current assignee: Shanghai Shengwei Electronic Technology Co ltd
Priority date: 2022-10-12
Filing date: 2022-10-12
Publication date: 2022-12-06

Abstract

A residual current protection device, a working state output method and a charging device are provided, wherein the residual current protection device comprises: the residual current sensor is used for sensing a residual current signal; the control unit is connected with the residual current sensor and is used for acquiring the current working state of the residual current protection device, determining the frequency information and the duty ratio information of the pulse width modulation signal corresponding to the working state, and generating the pulse width modulation signal according to the frequency information and the duty ratio information; and the output interface is connected with the control unit and used for outputting the pulse width modulation signal so as to indicate the working state through the frequency and the duty ratio of the pulse width modulation signal. The residual current protection device is simple in hardware structure, multiple in indicated information types and high in expandability.

Description

Residual current protection device, working state output method and charging equipment

Technical Field

The present invention generally relates to the field of residual current protection, and more particularly, to a residual current protection device, a working state output method, and a charging apparatus.

Background

An RCD (Residual Current Device) is a Residual Current protection Device for detecting the magnitude of leakage Current in a line. If no RCD is installed in the circuit, when a person or an animal contacts high voltage, leakage current can be generated to the ground, and when the leakage current exceeds a certain threshold value, the heart of the person or the animal can vibrate, so that the heart stops suddenly, and further life danger is caused. If the residual current protection device such as the RCD is installed in the circuit, when leakage current exists in the circuit and the magnitude of a residual current signal exceeds a set threshold value, the RCD sends an alarm signal to the action mechanism to trigger the action mechanism to quickly break the circuit, and therefore the purpose of protecting life safety is achieved.

The action mechanism is mainly used for breaking a circuit of the rear end power supply, and when the circuit is broken, the rear end of the breaker does not have voltage and current, so that the protection purpose is realized. The RCD board-mounted leakage module is widely applied to charging piles and charging guns at present, can be directly installed on a circuit board, and when an electric automobile is charged, the RCD is used for detecting whether leakage current exceeds a threshold value in the charging process, if the leakage current exceeds the threshold value, the RCD can send out an alarm signal to other devices in the circuit board to execute a command of stopping charging and disconnect a charging circuit, such as a closed relay or a circuit breaker mechanism.

In the design of the charging pile overall system with higher safety requirements, a redundancy design is advocated, however, the redundancy design inevitably brings great cost improvement, and the solution to be solved is to carry out fault self-diagnosis and fault indication as much as possible. However, the existing residual current protection device lacks the output indication function of the self working state, and cannot meet the requirements of customers needing to consider the functional safety.

Disclosure of Invention

A series of concepts in a simplified form are introduced in the summary section, which is described in further detail in the detailed description section. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.

An aspect of an embodiment of the present invention provides a residual current protection device, where the residual current protection device includes:

the residual current sensor is used for sensing a residual current signal;

the control unit is connected with the residual current sensor and is used for acquiring the current working state of the residual current protection device, determining the frequency information and the duty ratio information of the pulse width modulation signal corresponding to the working state, and generating the pulse width modulation signal according to the frequency information and the duty ratio information;

and the output interface is connected with the control unit and used for outputting the pulse width modulation signal so as to indicate the working state through the frequency and the duty ratio of the pulse width modulation signal.

In some embodiments, the control unit indicates the classification of the operating state by a frequency of the pulse width modulation signal or by a duty cycle of the pulse width modulation signal; the classification comprises at least two classifications, and each classification comprises at least two working states.

In some embodiments, the operating state includes a fault condition and a residual current magnitude.

In some embodiments, the frequencies include a first frequency and a second frequency, the first frequency in combination with different duty cycles being indicative of different fault conditions, the second frequency in combination with different duty cycles being indicative of different residual current levels.

In some embodiments, the frequency comprises a first duty cycle and a second duty cycle, the first duty cycle in combination with the different frequency being indicative of different fault conditions, the second duty cycle in combination with the different frequency being indicative of different residual current levels.

In some embodiments, the control unit is further configured to perform a self-check on the residual current protection device to obtain the fault condition.

In some embodiments, the number of the output interfaces is one, and the control unit is configured to output pulse width modulation signals with different frequencies and/or duty ratios through the one output interface successively; or, the output interfaces comprise at least two, and the control unit is used for outputting pulse width modulation signals with different frequencies and/or duty ratios through at least two output interfaces at the same time.

Another aspect of the embodiments of the present invention provides a method for outputting a working state, where the method is used for a residual current protection device, and the method includes:

acquiring the current working state of the residual current protection device;

determining frequency information and duty ratio information of a pulse width modulation signal corresponding to the working state, and generating the pulse width modulation signal according to the frequency information and the duty ratio information;

outputting the pulse width modulation signal to indicate the operating state by a frequency and a duty cycle of the pulse width modulation signal.

In some embodiments, the method further comprises indicating the classification of the operating state by a frequency of the pulse width modulated signal or by a duty cycle of the pulse width modulated signal; the classification comprises at least two classifications, and each classification comprises at least two working states.

In some embodiments, the operating conditions include a fault condition and a residual current level.

In some embodiments, the duty cycles include a first duty cycle and a second duty cycle, the first duty cycle in combination with the different frequencies to indicate different fault conditions, the second duty cycle in combination with the different frequencies to indicate different residual current levels.

In some embodiments, the method further comprises: and self-checking the residual current protection device to obtain the fault state.

In some embodiments, said outputting said pulse width modulated signal comprises: sequentially outputting pulse width modulation signals with different frequencies and/or duty ratios through the same output interface;

alternatively, pulse width modulated signals with different frequencies and/or duty cycles are output simultaneously through at least two output interfaces.

Another aspect of the embodiments of the present invention provides a charging apparatus, including:

the residual current protection device is used for outputting a pulse width modulation signal so as to indicate the working state of the residual current protection device through the frequency and the duty ratio of the pulse width modulation signal;

and the control device is connected with the residual current protection device and is used for receiving the pulse width modulation signal sent by the residual current protection device and determining the working state of the residual current protection device according to the frequency and the duty ratio of the pulse width modulation signal.

The residual current protection device, the working state output method and the charging equipment indicate different working states through the combination of different frequencies and duty ratios of the pulse width modulation signals, and are simple in hardware structure, multiple in indicatable information types and strong in expandability.

Drawings

The above and other objects, features and advantages of the present application will become more apparent by describing in more detail embodiments of the present application with reference to the attached drawings. The accompanying drawings are included to provide a further understanding of the embodiments of the application and are incorporated in and constitute a part of this specification, illustrate embodiments of the application and together with the description serve to explain the principles of the application. In the drawings, like reference numbers generally represent like parts or steps.

Fig. 1 is a circuit diagram of a residual current protection device according to an embodiment of the present invention;

FIG. 2 is a schematic flow chart diagram of a method of outputting operating conditions in accordance with one embodiment of the present invention;

fig. 3 is a schematic diagram of a charging device of one embodiment of the present invention.

Detailed Description

In the following description, numerous specific details are set forth in order to provide a more thorough understanding of the present invention. It will be apparent, however, to one skilled in the art, that the present invention may be practiced without one or more of these specific details. In other instances, well-known features have not been described in order to avoid obscuring the present invention.

It is to be understood that the present invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. In the drawings, the size and relative sizes of layers and regions may be exaggerated for clarity. Like reference numerals refer to like elements throughout.

It will be understood that when an element or layer is referred to as being "on," "adjacent to," "connected to" or "coupled to" another element or layer, it can be directly on, adjacent, connected or coupled to the other element or layer or intervening elements or layers may be present. In contrast, when an element is referred to as being "directly on," "directly adjacent to," "directly connected to" or "directly coupled to" other elements or layers, there are no intervening elements or layers present. It will be understood that, although the terms first, second, third, etc. may be used to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another element, component, region, layer or section. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the present invention.

Spatial relational terms such as "under," "below," "under," "above," "over," and the like may be used herein for convenience in describing the relationship of one element or feature to another element or feature as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, then elements or features described as "below" or "beneath" other elements or features would then be oriented "above" the other elements or features. Thus, the exemplary terms "under" and "under" can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatial descriptors used herein interpreted accordingly.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. As used herein, the term "and/or" includes any and all combinations of the associated listed items.

In order to provide a thorough understanding of the present invention, a detailed structure will be set forth in the following description in order to explain the present invention. The following detailed description of the preferred embodiments of the invention, however, the invention can be practiced otherwise than as specifically described.

The residual current protection device of the existing charging pile mainly outputs working state information through the following two modes. The first is to adopt the form of two-way or multi-way action signal output, and indicate different states according to the high-low level combination of the digital signal. For example, when two motion signal outputs are used, 4 states can be indicated by 00, 01, 10, 11. The scheme occupies more interface resources, some residual current protection devices are only provided with five interfaces in total, power supply and grounding interfaces are removed, only three interfaces are left, action instructions occupy two interfaces, and expansibility is limited. In addition, the scheme can indicate too few states, and only four states can be output when two paths of action signals are adopted.

The second is serial communication with other controllers through a communication interface form, so that infinite expandability is obtained. However, this solution requires the formulation of a non-standard communication protocol, which increases the complexity of the client code. If the serial port of the control unit is used, the reliability is poor; if other buses are used, additional chip investment is required, and the cost is increased.

In view of the above problems, embodiments of the present invention provide a residual current protection device, a working state output method, and a charging device, where the working state of the residual current protection device is indicated by a combination of a frequency and a duty ratio of a pulse width modulation signal, and the residual current protection device occupies fewer interface resources, has multiple kinds of indicatable information, and has high expandability.

Hereinafter, a residual current protection device, an operating state output method, and a charging device according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings. The features of the following examples and embodiments may be combined with each other without conflict.

Referring to fig. 1, a residual current protection device 100 according to an embodiment of the present invention at least includes a residual current sensor 110, a control unit 120, and an output interface 130, where the residual current sensor 110 is configured to sense a residual current signal; the control unit 120 is connected to the residual current sensor 110, and is configured to obtain a current working state of the residual current protection device, determine frequency information and duty ratio information of a pulse width modulation signal corresponding to the current working state, and generate the pulse width modulation signal according to the frequency information and the duty ratio information; the output interface 130 is connected to the control unit 120, and is configured to output a Pulse Width Modulation (PWM) signal to indicate an operating state of the residual current protection device 100 according to a frequency and a duty ratio of the PWM signal.

The residual current protection device 100 of the embodiment of the present invention uses a PWM peripheral that is commonly provided in the control device to output a PWM signal, and indicates the operating state of the residual current protection device 100 by adjusting the frequency and the duty ratio of the PWM signal. The device has simple hardware design, can not need additional hardware resources, does not increase additional hardware cost, has various types of indicatable information, and can basically cover the application of the residual current protection device 100; the expandability is strong, the customizability is strong, and the difficulty in realizing hardware and software is low.

The residual Current protection device 100 according to the embodiment of the present invention may adopt a fluxgate technology, wherein the residual Current inductor 110 may adopt a ZCT (Zero Current Transformer). A primary side three-phase wire of the zero sequence current transformer penetrates through the iron core, and a secondary coil is wound on the iron core. Under the normal condition, the primary side three-phase current of the zero sequence current transformer is symmetrical, and the vector sum is zero. When the system has single-phase earth fault, the sum of three-phase currents is not zero, zero-sequence magnetic flux occurs in the iron core, the magnetic flux induces potential on the secondary coil, and secondary current is generated.

In some embodiments, the residual current protection device 100 further includes a sampling resistor disposed between the zero sequence current transformer and the control unit 120, and the control unit 120 obtains the residual current signal through the sampling resistor. And, also include the oscillating circuit (OSC) set up between zero sequence current transformer and control unit 120, the control unit 120 applies the excitation current to the zero sequence current transformer through the oscillating circuit, in order to drive the ZCT coil, make its magnetic core magnetize, meanwhile, the control unit 120 can obtain the waveform signal voltage information including excitation voltage waveform through detecting the voltage on the sampling resistor, the voltage information includes the information of the magnetic flux of zero sequence too; the zero sequence magnetic flux information can be obtained by filtering the excitation waveform information through the filter, and the zero sequence magnetic flux is generated by the leakage current, so that the leakage current information can be obtained, and the function of detecting the alternating current leakage current and the direct current leakage current is realized.

Further, the residual current protection device 100 may adopt an open-loop or closed-loop type excitation method. The excitation frequency in the open-loop excitation mode is generated by an oscillation circuit, the oscillation frequency is comprehensively determined according to the characteristics of different transformers and the magnitude of a driving current signal, and once the excitation frequency is determined, the excitation frequency is fixed and cannot be randomly modified in the application process. In the closed loop type excitation mode, the excitation frequency is related to characteristic parameters such as the number of turns, bm, coil excitation voltage, sectional area Ac and the like of the ZCT transformer, a feedback signal is generated by comparing the voltage generated on the sampling resistor with the voltage pre-configured by the comparator, the feedback signal is fed back to an excitation circuit in the controller 120, the frequency of the excitation current is adjusted until the circuit is in a stable state, and the excitation frequency also tends to be stable at the moment.

It should be noted that the residual current sensor 110 used in the embodiment of the present invention is not limited to the ZCT using the magnetic modulation technology, and for example, the function of sensing the leakage current may also be implemented in a hall manner or any other suitable manner.

The residual current sensor 110 is directly or indirectly connected to the control unit 120, and the control unit 120 may be implemented as a Micro Control Unit (MCU), or may be implemented as other control units or circuits with similar functions. The control unit 120 is configured to obtain a current operating state of the residual current protection device 100, determine frequency information and duty ratio information of a PWM signal corresponding to the current operating state, and generate the PWM signal according to the determined frequency information and duty ratio information. The PWM signal has two important parameters, namely frequency and duty cycle. The frequency and the period are reciprocal, and the duty ratio refers to the proportion of high level in one period. The embodiment of the invention indicates the corresponding working state through the combination of the frequency and the duty ratio, and does not need to configure an additional algorithm at the client.

For example, a correspondence list between the plurality of operating states and the frequency information and the duty ratio information of the PWM signal may be stored in the control unit 120 in advance, and when the current operating state of the residual current protection device 100 is obtained, the frequency information and the duty ratio information corresponding to the current operating state are retrieved from the correspondence list, and then the PWM signal is generated according to the retrieved frequency information and the retrieved duty ratio information.

In some embodiments, the operating state indicated by the PWM signal specifically includes a residual current level. The control unit 120 is further configured to compare the residual current sensed by the residual current sensor 110 with a preset threshold, and generate a PWM signal to indicate the magnitude of the residual current when the magnitude of the residual current exceeds the preset threshold. In some embodiments, since the output of the output interface abruptly changes from 0 to the pwm signal when the residual current signal is greater than the preset threshold, the client may control the actuating mechanism to perform the line break when recognizing the rising edge of the pwm signal. Then, the control unit 120 locks the output interface and keeps outputting the PWM signal continuously within a preset time, so that the client has enough time to complete the duty cycle sampling of the PWM signal, thereby obtaining the magnitude of the corresponding residual current signal. Optionally, in some embodiments, when the residual current signal is greater than the preset threshold, the control unit may also control the output interface to output a high-low level signal to notify the client of the occurrence of the leakage fault, and then output a pulse width modulation signal of a period of time to notify the client of the magnitude of the residual current signal.

Further, the operating state indicated by the PWM signal may also include a fault state. The control unit 120 is further configured to perform self-test on the residual current protection device 100 to obtain a fault state, and generate a PWM signal to indicate the fault state when it is obtained that the residual current protection device 100 is in the fault state. In one embodiment, the control unit 120 is further connected to a self-test command input pin for receiving an external self-test command, where the self-test command is used to trigger the control unit 120 to start performing a system self-test to obtain a fault state. Besides the mode of receiving the self-test instruction, the system self-test can be triggered by other modes, such as a PWM mode, a timing self-test, a self-test when a current leakage phenomenon occurs, and the like.

In some embodiments, the control unit 120 may indicate the classification of the operating state by the frequency of the PWM signal. The working state classification comprises at least two working states, and each classification comprises at least two working states. After receiving the PWM signal, the client determines the classification of the operating state indicated by the PWM signal according to the frequency of the PWM signal, and then determines the specific operating state corresponding to the PWM in at least two operating states under the classification according to the duty ratio of the PWM signal. The classification of the working state can comprise two types of fault states and residual current magnitudes, and can also comprise more types; accordingly, the frequency of the PWM signal may include two or more. Similarly, the control unit 120 may also indicate the classification of the operation state by the duty ratio of the PWM signal and indicate the specific operation state under the classification by the frequency of the PWM signal.

For example, to distinguish whether the information indicated by the PWM signal is a fault condition or a residual current magnitude, the frequency of the PWM signal may be divided into two types, a first frequency and a second frequency, wherein the first frequency and the different duty cycle are combined to indicate different fault conditions, and the second frequency and the different duty cycle are combined to indicate different residual current magnitudes. Therefore, the client can firstly determine the type of the working state indicated by the PWM signal according to the frequency of the PWM signal, and then further determine the working state specifically indicated by the PWM signal under the type according to the duty ratio of the PWM signal. An exemplary correspondence of the frequency and duty ratio of the PWM signal to the operating state is shown in table 1:

TABLE 1

As another implementation, the duty cycle of the PWM signal includes a first duty cycle and a second duty cycle, the first duty cycle and the different frequency in combination are used to indicate different fault states, and the second duty cycle and the different frequency in combination are used to indicate different residual current magnitudes. The client may first determine the type of the operating state indicated by the PWM signal according to the duty ratio of the PWM signal, and then further determine the operating state specifically indicated by the PWM signal under the type according to the frequency of the PWM signal.

In some embodiments, the output interface 130 is one, and the output of the working states such as the fault state, the residual current magnitude, and the like is realized through a single interface, so that the occupation of interface resources is reduced. When at least two different kinds of operating state information need to be output, the control unit 120 may output the pulse width modulation signals with different frequencies and/or duty ratios through one output interface 130 in sequence. In other embodiments, the output interfaces include at least two, and when it is required to output at least two different operating state information, the control unit 120 may simultaneously output the pulse width modulation signals with different frequencies and/or duty ratios through the at least two output interfaces 120, so as to simultaneously transmit the at least two different operating state information. The at least two different kinds of operating state information may include a fault state and a residual current magnitude, or may include at least two different kinds of fault states, so that a plurality of kinds of fault state information can be presented simultaneously.

Illustratively, the control unit 120 may further include a power VCC pin, a GND ground pin, and the like, which are not described in detail herein, in addition to the output interface 130.

Based on the above description, the residual current protection device according to the embodiment of the present invention indicates different operating states through combinations of different frequencies and duty ratios of the pwm signals, and has a simple hardware structure, a variety of kinds of information that can be indicated, and strong expandability.

Another aspect of the embodiments of the present invention provides an operating state output method, which may be implemented by the residual current protection device described with reference to fig. 1. Only the main steps for describing the operation state output method will be described below, and more details can be referred to above.

FIG. 2 shows a schematic flow diagram of an operational status output method 200 according to one embodiment of the present invention. As shown in fig. 2, the method 200 for outputting the operating state according to the embodiment of the present invention includes the following steps:

in step S210, obtaining a current working state of the residual current protection device;

in step S220, determining frequency information and duty ratio information of a pwm signal corresponding to the operating state, and generating a pwm signal according to the frequency information and the duty ratio information;

in step S230, the pwm signal is output to indicate the operating state by the frequency and duty ratio of the pwm signal.

In some embodiments, the method further comprises: the classification of the operating state is indicated by the frequency of the PWM signal or by the duty ratio of the PWM signal. The working state classification comprises at least two working states, and each classification comprises at least two working states.

In some embodiments, the operating state indicated by the PWM signal includes a fault state and a residual current level. In this embodiment, the type of operating state it indicates may be represented by the frequency of the PWM signal, i.e. the frequency of the PWM signal comprises a first frequency and a second frequency, the first frequency in combination with different duty cycles being used to indicate different fault conditions, the second frequency in combination with different duty cycles being used to indicate different residual current levels. Alternatively, the type of operating state it indicates may be represented by the duty cycle of the PWM signal, i.e. the duty cycle of the PWM signal comprises a first duty cycle and a second duty cycle, the first duty cycle in combination with a different frequency being used to indicate a different fault condition, the second duty cycle in combination with a different frequency being used to indicate a different magnitude of the residual current.

Further, the method further comprises: and self-checking the residual current protection device to obtain the fault state of the residual current protection device.

In some embodiments, outputting the pulse width modulated signal comprises: sequentially outputting pulse width modulation signals with different frequencies and/or duty ratios through the same output interface; alternatively, pulse width modulated signals with different frequencies and/or duty cycles are output simultaneously through at least two output interfaces.

The working state output method 200 according to the embodiment of the present invention indicates different working states through combinations of different frequencies and duty ratios of the pwm signals, and has a simple hardware structure, a variety of kinds of information that can be indicated, and strong expandability.

As shown in fig. 3, the charging apparatus according to an embodiment of the present invention further includes the residual current protection device 310 and the control device 320 connected to the residual current protection device 310, where the residual current protection device 310 is configured to output a pulse width modulation signal to indicate an operating state of the residual current protection device through a frequency and a duty ratio of the pulse width modulation signal; the control device 320 is configured to receive the pwm signal sent by the residual current protection device 310, and determine the operating state of the residual current protection device 310 according to the frequency and the duty ratio of the pwm signal. The control device 320 includes, but is not limited to, a Micro Control Unit (MCU), which may be pre-configured with the correspondence between the frequency and duty ratio of the PWM signal and different operating states, and when receiving the PWM signal sent by the residual current protection device 310, determines the frequency and duty ratio of the received PWM signal, and determines the operating state represented by the PWM signal according to the frequency and duty ratio of the PWM signal.

The charging device of the embodiment of the invention can be realized as a charging device for charging vehicles such as a charging pile and a charging gun, the residual current protection device 310 can be a board-mounted residual current protection device which can be directly mounted on a PCB of the charging device, when the charging device charges an electric vehicle, the residual current protection device 310 can be used for detecting whether the magnitude of leakage current exceeds a threshold value in the charging process, and when the magnitude of the leakage current exceeds the threshold value, an alarm is sent to an MCU or other devices on the PCB to execute a command for stopping charging and disconnect a charging circuit, such as a closed relay or a circuit breaker mechanism.

In the description provided herein, numerous specific details are set forth. However, it is understood that embodiments of the invention may be practiced without these specific details. In some instances, well-known methods, structures and techniques have not been shown in detail in order not to obscure an understanding of this description.

Similarly, it should be appreciated that in the description of exemplary embodiments of the invention, various features of the invention are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the invention and aiding in the understanding of one or more of the various inventive aspects. However, the method of the present invention should not be construed to reflect the intent: that the invention as claimed requires more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive aspects lie in less than all features of a single disclosed embodiment. Thus, the claims following the detailed description are hereby expressly incorporated into this detailed description, with each claim standing on its own as a separate embodiment of this invention.

It will be understood by those skilled in the art that all of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and all of the processes or elements of any method or apparatus so disclosed, may be combined in any combination, except combinations where such features are mutually exclusive. Each feature disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise.

Furthermore, those skilled in the art will appreciate that while some embodiments described herein include some features included in other embodiments, rather than other features, combinations of features of different embodiments are meant to be within the scope of the invention and form different embodiments. For example, in the claims, any of the claimed embodiments may be used in any combination.

It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. The invention may be implemented by means of hardware comprising several distinct elements, and by means of a suitably programmed computer. In the unit claims enumerating several means, several of these means may be embodied by one and the same item of hardware. The usage of the words first, second and third, etcetera do not indicate any ordering. These words may be interpreted as names.

The above description is only for the specific embodiment of the present invention or the description thereof, and the protection scope of the present invention is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present invention, and the changes or substitutions should be covered within the protection scope of the present invention. The protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. A residual current protection device, characterized in that it comprises:

the residual current sensor is used for sensing a residual current signal;

2. The residual current protection device according to claim 1, characterized in that said control unit indicates the classification of said operating condition by the frequency of said pulse width modulation signal or by the duty cycle of said pulse width modulation signal; the classification comprises at least two classifications, and each classification comprises at least two working states.

3. The residual current protection device according to claim 1, characterized in that said operating conditions comprise fault conditions and residual current levels.

4. The residual current protection device of claim 3, wherein the frequencies comprise a first frequency and a second frequency, the first frequency in combination with different duty cycles being indicative of different fault conditions, the second frequency in combination with different duty cycles being indicative of different residual current levels.

5. The residual current protection device of claim 3, wherein the duty cycle comprises a first duty cycle and a second duty cycle, the first duty cycle in combination with different frequencies to indicate different fault conditions, the second duty cycle in combination with different frequencies to indicate different residual current levels.

6. A residual current protection device according to claim 3, characterized in that said control unit is also adapted to self-test said residual current protection device to obtain said fault condition.

7. The residual current protection device according to claim 1, wherein the output interface is one, and the control unit is configured to output pulse width modulation signals with different frequencies and/or duty ratios through the one output interface in sequence;

or, the output interfaces comprise at least two, and the control unit is used for outputting pulse width modulation signals with different frequencies and/or duty ratios through at least two output interfaces at the same time.

8. An operating state output method for a residual current protection device, the method comprising:

acquiring the current working state of the residual current protection device;

9. The method of claim 8, wherein the method further comprises: indicating the classification of the operating state by a frequency of the pulse width modulation signal or by a duty cycle of the pulse width modulation signal; the classification comprises at least two classifications, and each classification comprises at least two working states.

10. The method of claim 8, wherein the operating conditions include a fault condition and a magnitude of residual current.

11. The method of claim 9, wherein the frequency comprises a first frequency and a second frequency, the first frequency in combination with different duty cycles to indicate different fault conditions, the second frequency in combination with different duty cycles to indicate different residual current levels.

12. The method of claim 11, wherein the duty cycle comprises a first duty cycle and a second duty cycle, the first duty cycle in combination with different frequencies to indicate different fault conditions, the second duty cycle in combination with different frequencies to indicate different residual current levels.

13. The method of claim 8, wherein the method further comprises:

and self-checking the residual current protection device to obtain the fault state.

14. The method of claim 8, wherein the outputting the pulse width modulated signal comprises:

sequentially outputting pulse width modulation signals with different frequencies and/or duty ratios through the same output interface;

15. A charging apparatus, characterized in that the charging apparatus comprises:

a residual current protection device as claimed in any one of claims 1 to 7, which is arranged to output a pulse width modulated signal to indicate the operating condition of the residual current protection device by the frequency and duty cycle of the pulse width modulated signal;

and the control device is connected with the residual current protection device and used for receiving the pulse width modulation signal sent by the residual current protection device and determining the working state of the residual current protection device according to the frequency and the duty ratio of the pulse width modulation signal.