CN209927990U

CN209927990U - Residual current generating device and residual current action protector tester

Info

Publication number: CN209927990U
Application number: CN201920488574.6U
Authority: CN
Inventors: 陈智; 杨志
Original assignee: Siemens Circuit Protection Systems Ltd
Current assignee: Siemens Circuit Protection Systems Ltd
Priority date: 2019-04-11
Filing date: 2019-04-11
Publication date: 2020-01-10
Anticipated expiration: 2029-04-11

Abstract

The utility model discloses embodiment discloses residual current generating device and residual current operated protective device tester. The residual current generating device comprises: the zero-crossing detection module is used for generating a zero-crossing signal when detecting the zero point of the alternating-current voltage; the control module is connected with the zero-crossing detection module and used for generating a trigger command based on the zero-crossing signal; the first direct digital frequency synthesizer is connected with the control module and used for generating a first alternating voltage which is synchronous with the phase of the alternating voltage based on the trigger command; and the voltage-current conversion module is used for converting the first alternating voltage into current. The utility model discloses embodiment can restrict the wave form distortion, can conveniently adjust the phase place angle of residual current moreover.

Description

Residual current generating device and residual current action protector tester

Technical Field

The utility model relates to an electronic components technical field, especially residual current generating device and residual current operated protective device tester.

Background

The insulation performance of the electric wire is reduced due to some reason (such as mechanical damage, insulation aging, etc.), and abnormal current flows between the electric wire and the ground, which is called leakage current. Residual Current (Residual Current), i.e., leakage Current, refers to a Current whose sum of Current vectors of each phase (including neutral line) in the low-voltage distribution line is not zero.

The residual current operated protector is a mechanical switch or a combined electrical appliance which automatically breaks off a circuit when the residual current reaches or exceeds a given value under a specified condition, and is also called a leakage protector. The residual current operated protector is one of effective means for preventing electric shock accidents, and is also an important technical measure for preventing electric fire and electric equipment damage accidents caused by electric leakage.

Currently, when performing a functional test on a residual current operated protector product, it is usually necessary to provide a residual current synchronized with the input voltage. In addition, the phase angle of the residual current should be settable, such as the phase angle typically includes: AC; +0 °; -0 °; +90 °; -90 °; +135 °; -135 °; and so on.

Fig. 1 is a schematic diagram illustrating a generation process of a residual current synchronized with an input voltage in the prior art. In fig. 1, a Zero-cross detection (Zero Check) module 11 is connected to the line L and the neutral N of the ac voltage, respectively. The zero-crossing detection module 11 generates a zero-crossing signal when detecting a zero point of the alternating-current voltage; the Microprocessor (MCU)12 generates a voltage signal in a digital format synchronized with the ac voltage based on the zero-crossing signal; the digital-analog converter 13 converts the voltage signal in the digital format into a voltage signal in an analog format; the voltage-to-current converter 14 converts the voltage signal in analog format into a current signal, i.e., a residual current synchronized with the input voltage.

However, in this manner, the waveform distortion of the residual current is severe due to the clock resources of the microprocessor 12 and the slew rate of the digital-to-analog converter 12. Also, in this manner, it is difficult to adjust the phase angle of the residual current.

SUMMERY OF THE UTILITY MODEL

The utility model discloses embodiment provides residual current generating device and residual current operated protective device tester.

The utility model discloses embodiment's technical scheme as follows:

a residual current generating device comprising:

the zero-crossing detection module is used for generating a zero-crossing signal when detecting the zero point of the alternating-current voltage;

the control module is connected with the zero-crossing detection module and used for generating a trigger command based on the zero-crossing signal;

a first Direct Digital Synthesizer (DDS) is connected with the control module and used for generating a first alternating voltage synchronous with the phase of the alternating voltage based on the trigger command;

and the voltage-current conversion module is used for converting the first alternating voltage into current.

It can be seen that the embodiment of the present invention does not generate the voltage signal by the microprocessor, but generates the first ac voltage synchronized with the ac voltage based on the trigger command of the control module by the DDS good at digital processing, thereby limiting the waveform distortion of the residual current.

Furthermore, the embodiments of the present invention adopt the DDS having the digital-analog conversion function, without arranging an additional digital-analog converter, and the residual current generating device has a compact structure, thereby saving the arrangement space.

In one embodiment, further comprising:

the second DDS is connected with the control module and used for generating a second alternating voltage which is synchronous with the alternating voltage in phase and has a fixed amplitude value based on the trigger command;

a phase adjustment module disposed between the first DDS and the voltage-to-current conversion module for adjusting a phase angle of the first alternating voltage based on the second alternating voltage.

It is therefore clear that the embodiment of the present invention adjusts the phase angle of the first ac voltage based on the second ac voltage that is synchronous with the phase of the ac voltage and has a fixed amplitude, and the residual current provided by the residual current generating device is not only synchronous with the ac voltage, but also the phase angle of the residual current can be set.

In one embodiment, the phase adjustment module comprises:

an instantaneous amplitude detection unit for detecting an instantaneous amplitude of the second alternating voltage;

the comparator is connected with the instantaneous amplitude detection unit and used for comparing the instantaneous amplitude with a set value and generating a switch trigger command when the instantaneous amplitude is the same as the set value;

and the analog switch is connected with the comparator and used for adjusting the phase angle of the first alternating voltage based on the switch triggering command.

Therefore, the embodiment of the utility model provides a specific structure of phase place adjusting module has still been provided, can set up the phase place angle of residual current based on second alternating voltage's instantaneous amplitude testing result.

In one embodiment, the phase adjustment module further comprises:

and the setting value adjusting module is connected with the comparator and used for receiving a phase angle adjusting instruction containing an updating value and adjusting the setting value based on the updating value.

Therefore, the embodiment of the present invention can also adjust the setting value, and thereby change the phase angle of the residual current.

In one embodiment, further comprising:

and the amplitude modulation module is connected with the first DDS and is used for modulating the amplitude of the first alternating voltage.

Therefore, the amplitude of the first alternating voltage is adjusted through the amplitude modulation module, the current value of the residual current can be correspondingly adjusted, and therefore the residual current with multiple current value levels can be output.

In one embodiment, the control module includes an MCU, a Central Processing Unit (CPU), or a Field-Programmable Gate Array (FPGA).

Therefore, the control module has various embodiments and is convenient to apply.

In one embodiment, further comprising:

and the current output module is connected with the voltage-current conversion module and used for outputting the current.

Therefore, based on the current output module, the residual current can be conveniently output.

A residual current operated protector tester comprises a residual current generating device as described above.

Therefore, the utility model discloses embodiment still provides a residual current operated protective device tester with residual current takes place function. Based on this residual current operated protective device tester, can conveniently carry out the test to residual current operated protective device.

Drawings

Fig. 1 is a schematic diagram illustrating a generation process of a residual current synchronized with an input voltage in the prior art.

Fig. 2 is a first exemplary structure diagram of the residual current generating device according to the present invention.

Fig. 3 is a second exemplary structure diagram of the residual current generating device according to the present invention.

Fig. 4 is an exemplary structure diagram of the phase control module according to the present invention.

Fig. 5 is an exemplary structure diagram of the tester for residual current operated protection device of the present invention.

Wherein the reference numbers are as follows:

reference numerals	Means of
		11	Zero-crossing detection module
12	Microprocessor
		13	Digital-to-analog converter
14	Voltage-current converter
		20	Residual current generating device
21	Zero-crossing detection module
		22	Control module
23	First DDS
		24	Voltage-current conversion module
25	Current output module
		26	Amplitude modulation module
27	Phase adjusting module
		28	Second DDS
271	Instantaneous amplitude detection unit
		272	Comparator with a comparator circuit
273	Analog switch
		30	Residual current operated protector tester

Detailed Description

In order to make the technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the embodiments described herein are merely illustrative of the present invention and are not intended to limit the scope of the invention.

For simplicity and clarity of description, the aspects of the present invention are described below by describing several representative embodiments. Numerous details of the embodiments are set forth to provide an understanding of the principles of the invention. It is clear, however, that the solution according to the invention can be implemented without being limited to these details. Some embodiments are not described in detail, but rather only to give a framework, in order to avoid unnecessarily obscuring aspects of the present invention. Hereinafter, "including" means "including but not limited to", "according to … …" means "at least according to … …, but not limited to … … only". In view of the language convention of chinese, the following description, when it does not specifically state the number of a component, means that the component may be one or more, or may be understood as at least one.

In the related art residual current generation process, a microprocessor generates a voltage signal synchronized with an alternating voltage, a digital-analog converter converts the voltage signal into a voltage signal of an analog format, and then the voltage signal of the analog format is converted into a residual current. The applicant found that: the waveform distortion of the residual current generated by the prior art is severe due to the clock resources of the microprocessor and the slew rate of the digital-to-analog converter.

In order to solve the technical problem of waveform distortion, the applicant proposes: the voltage signal of the residual current is generated by the DDS which is better in digital processing based on a trigger command sent by a control module such as a microprocessor instead of the voltage signal generated by the microprocessor, so that the waveform distortion of the residual current can be improved or overcome.

As shown in fig. 2, the residual current generating device 20 includes:

a zero-crossing detection module 21 for generating a zero-crossing signal when a zero point of the ac voltage is detected;

the control module 22 is connected with the zero-crossing detection module 21 and is used for generating a trigger command based on the zero-crossing signal;

a first DDS23 connected to the control module 22 for generating a first ac voltage phase-synchronized with the ac voltage based on the trigger command;

and a voltage-current conversion module 24 for converting the first alternating voltage into a current.

The zero-cross detection module 21 is connected to the live line L and the zero line N of the ac voltage, respectively. When the zero-cross detection module 21 detects that the waveform of the alternating-current voltage is converted from the positive half cycle to the negative half cycle through the zero position, a zero-cross signal is generated and sent to the control module 22. Control module 22 generates a trigger command based on the zero crossing signal provided by zero crossing detection module 21 and sends the trigger command to a first DDS23 coupled to control module 22. The first DDS23 generates a first ac voltage that is phase-synchronized (i.e., time-synchronized) with the ac voltage based on the trigger command. Then, the voltage-current conversion module 24 converts the first ac voltage into a current, which is a residual current synchronized with the ac voltage.

Preferably, the alternating voltage may be implemented as alternating mains. For example, the specific parameters of the ac mains include: a sinusoidal waveform; line voltage 380 volts (V); a phase voltage of 220V; frequency 50 hertz (Hz), and so on.

Preferably, the control module 22 may be implemented as an MCU, CPU or FPGA, or the like. Preferably, the first DDS23 can be implemented as various types of DDS chips, such as AD9830, AD9831, AD9832, AD9833, AD9834, AD9835, AD9850, AD9851, AD9852, AD9853, AD9854, AD9858, and so on.

While the above exemplary description describes a typical example of an ac voltage, control module 22 and first DDS23, those skilled in the art will appreciate that this description is exemplary only and is not intended to limit the scope of embodiments of the invention.

In particular, the first DDS23 may include a frequency control register, a high-speed phase accumulator, a sine calculator, a high-speed digital-to-analog converter, and a low-pass filter. Wherein: the frequency control register loads and registers a frequency control code corresponding to the trigger command in a serial or parallel mode; the phase accumulator performs phase accumulation in each clock period according to the frequency control code to obtain a phase value; a sine calculator generates a digitized sine wave (e.g., by table lookup) having a predetermined initial amplitude based on the phase value; a high-speed digital-to-analog converter that converts the digitized sine wave to a sine wave in an analog format; the low-pass filter performs low-pass filtering processing on the sine wave in the analog format, and the output result of the low-pass filter is the first alternating voltage in phase synchronization with the alternating voltage.

Compared with the traditional frequency synthesizer, the DDS technology has the advantages of low cost, low power consumption, high resolution, fast switching time and the like. The utility model discloses the embodiment no longer produces voltage signal by microprocessor, but produces first alternating voltage based on control module's trigger command by the DDS that is good at digital processing to can guarantee the waveform of residual current.

In one embodiment, the residual current generating device 20 further comprises:

the amplitude modulation module 26 is connected to the first DDS23 and is configured to modulate the amplitude of the first ac voltage.

Wherein, the amplitude modulation module 26 may adjust the amplitude of the first ac voltage having a predetermined initial amplitude, which is output by the first DDS23, based on a user operation command.

It can be seen that, by adjusting the amplitude of the first ac voltage, the current value of the residual current output by the voltage-current conversion module 24 can be adjusted accordingly, so that the residual currents of multiple current value levels can be output.

In one embodiment, the residual current generating device 20 further comprises a current output module 25. The current output module 25 is connected to the voltage-current conversion module 24 for outputting current. For example, the current output module 25 may be implemented as a current output terminal.

In various test environments related to residual current, it is generally expected that the phase angle of the generated residual current is settable. For example, the phase angles may include: AC; +0 °; -0 °; +90 °; -90 °; +135 °; -135 °; and so on.

The utility model discloses embodiment has still provided a residual current generating device. The residual current provided by the residual current generating device is kept synchronous with the alternating voltage, and the phase angle of the residual current can be set.

It can be seen that the residual current generating device 20 of fig. 3 comprises all the functional blocks of the residual current generating device 20 of fig. 2. Specifically, the method comprises the following steps: a zero-crossing detection module 21 for generating a zero-crossing signal when a zero point of the ac voltage is detected; the control module 22 is connected with the zero-crossing detection module 21 and is used for generating a trigger command based on the zero-crossing signal; a first DDS23 connected to the control module 22 for generating a first ac voltage phase-synchronized with the ac voltage based on the trigger command; a voltage-current conversion module 24 for converting the first alternating voltage into a current; the amplitude modulation module 26 is connected with the first DDS23 and is used for modulating the amplitude of the first alternating voltage; and the current output module 25 is connected with the voltage-current conversion module 24 and is used for outputting the current provided by the voltage-current conversion module 24.

In comparison with the residual current generating device 20 of fig. 2, the residual current generating device 20 shown in fig. 3 further comprises:

the second DDS28 is connected to the control module 22, and is configured to receive a trigger command generated by the control module 22 based on the zero-crossing signal, and generate a second ac voltage that is phase-synchronized with the ac voltage and has a fixed amplitude based on the trigger command;

and a phase adjusting module 27, arranged between the first DDS23 and the voltage-current converting module 24, for adjusting a phase angle of the first alternating voltage based on the second alternating voltage.

Preferably, the second DDS28 can be implemented as various types of DDS chips, such as AD9830, AD9831, AD9832, AD9833, AD9834, AD9835, AD9850, AD9851, AD9852, AD9853, AD9854, AD9858, and so on.

In particular, the second DDS28 may contain a frequency control register, a high-speed phase accumulator, a sine calculator, a high-speed digital-to-analog converter, and a low-pass filter. Wherein: the frequency control register loads and registers a frequency control code corresponding to the trigger command in a serial or parallel mode; the phase accumulator performs phase accumulation in each clock period according to the frequency control code to obtain a phase value; a sine calculator generates a digitized sine wave having a fixed amplitude based on the phase value; a high-speed digital-to-analog converter that converts the digitized sine wave to a sine wave in an analog format; the low-pass filter performs low-pass filtering processing on the sine wave in the analog format, the output result of the low-pass filter is the second alternating voltage which is synchronous with the alternating voltage in phase, and the waveform of the second alternating voltage has a fixed amplitude.

A phase adjustment module 27 arranged between the first DDS23 and the voltage-to-current conversion module 24 adjusts the phase angle of the first alternating voltage based on the second alternating voltage of fixed amplitude. Then, the voltage-current conversion module 24 converts the first ac voltage whose phase angle has been adjusted by the phase adjustment module 27 into a current. The current output module 25 outputs the current provided by the voltage-current conversion module 24.

The phase control module 27 of fig. 3 is described in detail below.

As can be seen from fig. 4, the phase adjustment module 27 includes:

an instantaneous amplitude detection unit 271 for detecting an instantaneous amplitude of the second alternating voltage;

a comparator 272 connected to the instantaneous amplitude detection unit 271 for comparing the instantaneous amplitude with a set value and generating a switch trigger command when the instantaneous amplitude is the same as the set value;

an analog switch 273 is connected to the comparator 272 for adjusting the phase angle of the first ac voltage based on the switch trigger command.

The corresponding relationship between the respective instantaneous amplitudes and the respective instantaneous phase angles in the waveform of the second alternating voltage is prestored in the comparator 272. The comparator 272 can determine the corresponding instantaneous phase angle of the second ac voltage based on the instantaneous amplitude of the second ac voltage detected by the instantaneous amplitude detection unit 271. Since the second alternating voltage is synchronous with the first alternating voltage and the amplitude of the second alternating voltage is fixed, the phase adjustment for the first alternating voltage can be achieved by setting a set value for instructing the start or end of the phase angle control of adjusting the first alternating voltage in the comparator 272.

For example, assume that the phase angle of the first alternating voltage output by the first DDS23 is expected to be +90 °, that is, the first DDS23 is expected to output a partial waveform of the first alternating voltage waveform having an instantaneous phase angle in the range of [ +90 ° +180 ° ]. Further, based on the correspondence relationship between the respective instantaneous amplitudes and the respective instantaneous phase angles in the waveform of the second alternating voltage prestored in the comparator 272, it is known that the instantaneous amplitude of the second alternating voltage is 1 volt when the phase angle of the second alternating voltage is +90 °; when the phase angle of the second alternating voltage is +180 °, the instantaneous amplitude of the second alternating voltage is 0 volt. Therefore, the first set value (1 volt) and the second set value (0 volt) are prestored in the comparator 272.

The instantaneous amplitude detection unit 271 continuously detects the instantaneous amplitude of the second alternating voltage. When the comparator 272 determines that the instantaneous amplitude is the same as the first set value (1 volt), that is, determines that the phase angle of the second alternating voltage reaches +90 °, since the second alternating voltage is synchronized with the first alternating voltage, it can be determined that the phase angle of the first alternating voltage also reaches +90 °, the comparator 272 generates a switch-on command, and the analog switch 273 allows the first DDS23 to start outputting the first alternating voltage waveform based on the switch-on command. Then, when the comparator 272 determines that the instantaneous amplitude becomes the same as the second set value (0 volt), that is, determines that the phase angle of the second alternating voltage is +180 °, since the second alternating voltage is synchronized with the first alternating voltage, it can be determined that the phase angle of the second alternating voltage also reaches + +180 °, the comparator 272 generates a switch-off command, and the analog switch 273 does not allow the first DDS23 to output the first alternating voltage waveform any more based on the switch-off command. Therefore, based on the above-described operation of the analog switch, the first DDS23 outputs a partial waveform in the first ac voltage waveform, that is, a waveform having an instantaneous phase angle range of [ +90 ° - +180 ° ].

In one embodiment, the phase adjustment module 27 further comprises: the setting value adjusting module 274 is connected to the comparator 272, and is configured to receive a phase angle adjustment command including an update value, and adjust the setting value based on the update value. It can be seen that the phase angle of the first ac voltage can also be adjusted based on adjusting the setting value held in the comparator 272.

The phase adjustment module 27 is described above by taking as an example that the phase angle of the first ac voltage output by the first DDS23 is expected to be +90 °, and those skilled in the art will appreciate that this description is merely exemplary. In fact, the phase angle of the first ac voltage output by the first DDS23 may further include: AC; +0 °; -0 °; +90 °; -90 °; +135 °; -135 °; and the like, the embodiments of the present invention are not limited thereto.

The utility model discloses embodiment has still provided a residual current operated protective device tester.

Fig. 5 is an exemplary structure diagram of the tester for residual current operated protection device of the present invention. The residual current operated protector tester 30 includes a residual current generating device 20 as described above.

It should be noted that not all the modules in the above structure diagrams are necessary, and some modules may be omitted according to actual needs. The division of each module is only for convenience of describing adopted functional division, and in actual implementation, one module may be divided into multiple modules, and the functions of multiple modules may also be implemented by the same module, and these modules may be located in the same device or in different devices.

The hardware modules in the various embodiments may be implemented mechanically or electronically. For example, a hardware module may include specially designed permanent circuitry or logic devices (e.g., a special purpose processor such as an FPGA) for performing specific operations. A hardware module may also include programmable logic devices or circuits (e.g., including a general-purpose processor or other programmable processor) for performing specific operations. The implementation of the hardware module in a mechanical manner, or in a dedicated permanent circuit, or in a temporarily configured circuit, may be determined by cost and time considerations.

The above description is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. Residual current generating device (20), characterized in that it comprises:

a zero-crossing detection module (21) for generating a zero-crossing signal when a zero point of the alternating voltage is detected;

a control module (22) connected with the zero-crossing detection module (21) and used for generating a trigger command based on the zero-crossing signal;

a first direct digital frequency synthesizer (23) connected to the control module (22) for generating a first alternating voltage phase-synchronized to the alternating voltage based on the trigger command;

a voltage-to-current conversion module (24) for converting the first alternating voltage into a current.

2. The residual current generating device (20) according to claim 1, further comprising:

a second direct digital frequency synthesizer (28) connected to the control module (22) for generating a second alternating voltage having a fixed amplitude and phase-synchronized with the alternating voltage based on the trigger command;

a phase adjustment module (27) arranged between the first direct digital frequency synthesizer (23) and the voltage-to-current conversion module (24) for adjusting a phase angle of the first alternating voltage based on the second alternating voltage.

3. The residual current generating device (20) according to claim 2, characterized in that said phase adjusting module (27) comprises:

an instantaneous amplitude detection unit (271) for detecting an instantaneous amplitude of the second alternating voltage;

a comparator (272) connected to the instantaneous amplitude detection unit (271) for comparing the instantaneous amplitude with a set value, and generating a switch trigger command when the instantaneous amplitude is the same as the set value;

an analog switch (273) connected to the comparator (272) for adjusting the phase angle of the first alternating voltage based on the switch trigger command.

4. The residual current generating device (20) according to claim 3, characterized in that said phase adjusting module (27) further comprises:

a setting value adjustment module (274), coupled to the comparator (272), for receiving a phase angle adjustment command including an update value and adjusting the setting value based on the update value.

5. The residual current generating device (20) according to claim 1, further comprising:

an amplitude modulation module (26) connected to the first direct digital frequency synthesizer (23) for modulating the amplitude of the first alternating voltage.

6. The residual current generating device (20) according to any one of claims 1-5, wherein the control module (22) comprises a micro control unit, a central processing unit or a field programmable gate array.

7. The residual current generating device (20) according to any one of claims 1-5, further comprising:

and the current output module (25) is connected with the voltage-current conversion module (24) and is used for outputting the current.

8. Residual current operated protector tester (30), characterized by comprising a residual current generating device (20) according to claim 1.