CN209803295U

CN209803295U - Residual current generating device and residual current action protector tester

Info

Publication number: CN209803295U
Application number: CN201920488589.2U
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: 2019-12-17
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 human-computer interface module is used for receiving a first configuration parameter; the control module is connected with the human-computer interface module and used for generating a trigger command containing the first configuration parameter; a direct digital frequency synthesizer module connected to the control module for generating an alternating voltage based on the trigger command, the frequency of the alternating voltage corresponding to the first configuration parameter; and the voltage-current conversion module is used for converting the alternating voltage into current. The utility model discloses the embodiment can export the residual current of high frequency, and the effective value of residual current is the adjustable 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.

At present, when the residual current operated protective device product is subjected to function test, the residual current with higher frequency is generally required to be used, and the frequency and the effective value of the residual current are required to be adjustable. For example, in T2.6 of item 5.1 of the national standard GB18499, testing for common mode conducted disturbances in a frequency range below 150 kilohertz (kHz) is required, thus requiring a residual current frequency of up to 150kHz and an effective value of current of up to 66 milliamperes (mA). Moreover, for the type-B residual current operated circuit breaker, the national standard GB22794 requires that the residual current frequency reaches 1kHz and the residual current effective value reaches 420 mA.

fig. 1 is a schematic diagram illustrating a generation process of a residual current in the prior art. In fig. 1, a Microprocessor (MCU)11 generates a voltage signal in a digital format; the digital-analog converter 12 converts the voltage signal in the digital format into a voltage signal in an analog format; the voltage-current converter 13 converts the voltage signal in analog format into a current signal, i.e., a residual current.

However, in this manner, limited by the clock resources of the microprocessor 11 and the slew rate of the digital-to-analog converter 12, the frequency of the generated residual current is limited. For example, taking the example of generating a sine wave of 150kHz, if 100 points are output every cycle, the refresh frequency of the MCU11 and the digital-to-analog converter 12 needs to reach 15 megahertz (MHz), which is quite harsh for both the MCU11 and the digital-to-analog converter 12, and therefore the frequency of the residual current that can be output by this scheme is limited.

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 human-computer interface module is used for receiving a first configuration parameter;

the control module is connected with the human-computer interface module and used for generating a trigger command containing the first configuration parameter;

A Direct Digital Synthesizer (DDS) module connected to the control module and configured to generate an AC voltage based on the trigger command, wherein a frequency of the AC voltage corresponds to the first configuration parameter;

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

It can be seen that the embodiment of the utility model discloses not produce voltage signal by MCU, but by supporting that high frequency and DDS that frequency accuracy is high produce the alternating voltage of corresponding frequency based on the trigger command that control module sent, contained frequency configuration parameter, can improve or overcome the limited problem of frequency of residual current to can improve frequency accuracy.

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 of the method of the present invention,

The human-computer interface module is also used for receiving a second configuration parameter; the control module is further used for generating a control command containing the second configuration parameter;

The residual current generation device further comprises:

The amplitude modulation module is connected with the control module and the DDS module and used for generating an amplitude modulation signal corresponding to the second configuration parameter based on the control command and sending the amplitude modulation signal to the DDS module;

The DDS module is further configured to adjust the amplitude of the alternating voltage based on the amplitude modulation signal.

Therefore, the effective value of the residual current generated by the embodiment of the present invention is settable.

In one embodiment, further comprising:

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

It is visible, the utility model discloses the embodiment sets up current output module in residual current generating device, can conveniently export the residual current.

in one embodiment, the amplitude modulation module includes a digital-to-analog converter.

Therefore, the effective value of the residual current can be controlled based on the digital-to-analog converter, and the accuracy of the effective value of the output current is high.

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

thus, the control module has a variety of embodiments.

In one embodiment, the human interface module comprises a rotary encoder or a touch screen.

it can be seen that the human interface module has a variety of embodiments.

In one embodiment, the DDS module includes: an AD9830 chip, an AD9831 chip, an AD9832 chip, an AD9833 chip, an AD9834 chip, an AD9835 chip, an AD9850 chip, an AD9851 chip, an AD9852 chip, an AD9853 chip, an AD9854 chip or an AD9858 chip.

Thus, there are a variety of embodiments of the DDS module.

in one embodiment, the DDS module includes an AD9850 chip, and the digital-to-analog converter includes an AD9731 chip, wherein:

And the No. 20 pin of the AD9731 chip is connected with the No. 12 pin of the AD9850 chip.

Therefore, the AD9731 chip is convenient to send amplitude modulation signals to the AD9850 chip by connecting the No. 20 pin of the AD9731 chip with the No. 12 pin of the AD9850 chip.

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 in the prior art.

Fig. 2 is an exemplary structure diagram of the residual current generating device of the present invention.

Fig. 3 is an exemplary circuit diagram of the residual current generating device of the present invention.

Fig. 4 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	MCU
12	Digital-to-analog converter
		13	Voltage-current converter
20	Residual current generating device
		21	Human-machine interface module
22	control module
		23	DDS module
231	AD9850 chip
		232	Peripheral circuit of AD9850 chip
24	Voltage-current conversion module
		25	Current output module
26	Amplitude modulation module
		261	AD9731 chip
262	Peripheral circuit of AD9731 chip
		28	Crystal oscillator circuit
29	Display device
		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 residual current generation process in the prior art, the MCU generates a voltage signal in a digital format; the digital-analog converter converts the voltage signal in a digital format into a voltage signal in an analog format; the voltage-current converter converts the voltage signal in the analog format into a current signal, namely the residual current. The applicant found that: the frequency of the residual current generated in the prior art is limited and the high frequency requirement is difficult to achieve due to the limitation of the clock resource of the MCU and the conversion rate of the digital-analog converter.

to solve the frequency-limited technical problem, the applicant proposes: the voltage signal is not generated by the MCU, but the DDS supporting high frequency and high frequency precision generates alternating current voltage with corresponding frequency based on a trigger command containing frequency configuration parameters sent by control modules such as the MCU and the like, so that the problem of frequency limitation of residual current can be improved or overcome.

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

A human-machine interface module 21 for receiving a first configuration parameter;

The control module 22 is connected with the human-machine interface module 21 and used for generating a trigger command containing first configuration parameters;

a DDS module 23, connected to the control module 22, for generating an ac voltage based on the trigger command, the frequency of the ac voltage corresponding to the first configuration parameter;

And a voltage-current conversion module 24, configured to convert the ac voltage into a current, where the current is a residual current.

The human-machine interface module 21 is an interface of an input/output device for establishing contact between a human and a computer and exchanging information. For example, the human interface module 21 may be implemented as a touch screen or a rotary encoder.

When the human interface module 21 is implemented as a touch screen, the touch screen receives the first configuration parameters based on a touch operation. When the human interface module 21 is implemented as a rotary encoder, the rotary encoder receives the first configuration parameters based on the rotation operation. The human-machine interface module 21 receives a first configuration parameter for configuring the frequency of the residual current output by the residual current generating device 20.

The control module 22 obtains and stores the first configuration parameter from the human-machine interface module 21. Preferably, the control module 22 may be implemented as an MCU, CPU or FPGA, or the like. The control module 22 generates a trigger command containing the first configuration parameters and sends the trigger command to the DDS module 23. The DDS module 23 generates an alternating voltage based on the trigger command, the frequency of which corresponds to the first configuration parameter.

In particular, the DDS module 23 may contain frequency control registers, high-speed phase accumulators, sine calculators, high-speed digital-to-analog converters, and low-pass filters. Wherein: the frequency control register loads and registers a frequency control code corresponding to the first configuration parameter 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) 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 alternating voltage which can be converted into the residual current by the voltage-current conversion module 24.

Wherein the frequency of the ac voltage corresponding to the first configuration parameter includes the following:

Case (1), the frequency of the alternating voltage is equivalent to the frequency value specified by the first configuration parameter.

for example, the human interface module 21, implemented as a rotary encoder, receives the first configuration parameters. Assume that the first configuration parameter contains a value field of "100". The control module 22 generates a trigger command containing the value field "100". The DDS module 23 generates an ac voltage with a frequency value of 100kHz based on the value field "100" contained in the trigger command.

Case (2), the frequency of the alternating voltage is mapped based on the first configuration parameter.

For example, the control module 22 prestores a corresponding relationship between the frequency indication field of each level and a specific frequency value. The human interface module 21, implemented as a touch screen, receives the first configuration parameters. It is assumed that the first configuration parameter comprises a frequency indication field "first class". The control module 22 determines that the frequency value corresponding to the "first level" is 120kHz based on the correspondence between the frequency indication field of each level and the specific frequency value, and generates a trigger command including the value field "120". The DDS module 23 generates an ac voltage with a frequency value of 120kHz based on the value field "120" contained in the trigger command.

Preferably, the DDS module 23 can include various types of DDS chips, such as an AD9830 chip, an AD9831 chip, an AD9832 chip, an AD9833 chip, an AD9834 chip, an AD9835 chip, an AD9850 chip, an AD9851 chip, an AD9852 chip, an AD9853 chip, an AD9854 chip, or an AD9858 chip, and so on.

While the above exemplary description describes a typical example of the control module 22 and the DDS module 23, those skilled in the art will appreciate that this description is merely exemplary and is not intended to limit the scope of embodiments of the present invention.

It can be seen that the embodiment of the utility model discloses no longer produce voltage signal by MCU, but produce the alternating voltage who corresponds the frequency based on the trigger command who contains first configuration parameter by supporting high frequency and DDS that frequency precision is high, can export the residual current of high frequency, improve or overcome the limited problem of frequency of residual current to can improve frequency precision. For example, taking the DDS module 23 implemented as an AD9850 chip as an example, the system clock can reach up to 125MHz, the frequency of the output sine wave can reach several tens of MHz, and when the 125MHz system clock is used, the frequency resolution is 0.029Hz, so the DDS module also has good frequency precision.

in addition, when the frequency of the residual current of output needs to be changed, only need to change the trigger command in the first configuration parameter can, the utility model discloses embodiment can also dispose the frequency of residual current in a flexible way.

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

In one embodiment, the specific time at which the control module 22 sends the trigger command is configurable. For example, the control module 22 may be further coupled to a zero crossing detection module (not shown in fig. 1). The zero-crossing detection module is respectively connected with a live wire L and a zero line N of alternating current commercial power. When the zero-cross detection module 21 detects that the waveform of the alternating current commercial power is converted from the positive half cycle to the negative half cycle and passes through the zero position, a zero-cross signal is generated and sent to the control module 22. When receiving the zero-crossing signal provided by the zero-crossing detection module 21, the control module 22 generates a trigger command containing a first configuration parameter, and sends the trigger command to the DDS module 23 connected to the control module 22. The DDS module 23 generates an ac voltage synchronized with the ac mains based on the trigger command, and the frequency of the ac voltage corresponds to the first configuration parameter. Then, the voltage-current conversion module 24 converts the ac voltage into a current, which is a residual current synchronized with the ac mains and having a frequency corresponding to the first configuration parameter.

it is also generally expected that a valid value of the generated residual current is settable in various test environments related to the residual current.

in one embodiment, the human-machine interface module 21 is further configured to receive a second configuration parameter; the control module 22 is further configured to generate a control command including the second configuration parameter. The residual current generating device 20 further comprises: the amplitude modulation module 26 is connected with the control module 22 and the DDS module 23, and is used for generating an amplitude modulation signal corresponding to the second configuration parameter based on the control command and sending the amplitude modulation signal to the DDS module 23; the DDS module 23 is further configured to adjust the amplitude of the ac voltage based on the amplitude modulation signal.

Wherein, when the human-machine interface module 21 is implemented as a touch screen, the touch screen receives the second configuration parameter based on a touch operation. When the human interface module 21 is implemented as a rotary encoder, the rotary encoder receives the second configuration parameters based on the rotation operation. The second configuration parameter received by the human-machine interface module 21 is used for configuring the effective value of the residual current output by the residual current generating device 20.

the control module 22 obtains and stores the second configuration parameter from the human-machine interface module 21. The control module 22 generates a control command containing the second configuration parameters and sends the control command to the amplitude modulation module 26.

The amplitude modulation module 26 stores a predetermined corresponding relationship between the second configuration parameter and the amplitude modulation signal. The amplitude modulation module 26 determines a corresponding amplitude modulation signal based on the second configuration parameter included in the control command, and sends the amplitude modulation signal to the DDS module 23, so that the DDS module 23 adjusts the amplitude of the ac voltage based on the amplitude modulation signal, thereby adjusting the effective value of the residual current.

For example, assume that when the DDS module 23 outputs an AC voltage of 300 volts in magnitude, the residual current is 150 mA. The human interface module 21, implemented as a rotary encoder, receives the second configuration parameters. The second configuration parameter comprises a value field "150" for instructing the residual current generating device 20 to output a residual current with a valid value of 150 mA. The control module 22 generates a control command containing the value field "150" and sends the control command to the amplitude modulation module 26. Based on the value field "150" contained in the control command, the amplitude modulation module 26 determines, by using the correspondence relationship between the second configuration parameter and the amplitude modulation signal stored in advance, an amplitude modulation current value corresponding to the value field "150", for example, 15mA, and sends an amplitude modulation current with a current magnitude of 15mA to the DDS module 23. The DDS module 23 stores in advance a correspondence between the amplitude-modulated current and the amplitude of the ac voltage. After detecting the 15mA amplitude-modulated current, the DDS module 23 determines that the voltage amplitude corresponding to the amplitude-modulated current is 300 volts, and outputs an ac voltage with a voltage amplitude of 300 volts, thereby adjusting the effective value of the residual current to 150 mA.

Therefore, the embodiment of the present invention can also adjust the effective value of the residual current based on the second configuration parameter received by the human-machine interface module 21. When the effective value of the residual current needs to be changed, the updated second configuration parameter is received again only on the human-computer interface module 21, and the effective value of the residual current is updated based on the updated second configuration parameter, so that the operation of a user is facilitated.

Preferably, the amplitude modulation module 26 comprises a digital-to-analog converter. For example, the digital-to-analog converter may include an AD9731 chip, an AD5314 chip, an AD5315 chip, an AD5316 chip, or an AD5317 chip, among others.

While the above exemplary items describe typical examples of amplitude modulation module 26, those skilled in the art will appreciate that this description is merely exemplary and is not intended to limit the scope of embodiments of the present invention.

In fig. 3, the human-machine interface module 21 comprises two rotary encoders, one for receiving the frequency configuration parameters and the other for receiving the current effective value configuration parameters. The control module 22 is embodied as an MCU. The AD9850 chip 231 and its peripheral circuits 232 constitute the DDS module 23 as shown in fig. 2. The AD9731 chip 261 and its peripheral circuits 262 constitute the amplitude modulation module 26 shown in fig. 2. The AD9850 chip 231 is also connected to the crystal oscillator circuit 28.

pin No. 20 (i.e., output current pin I) of AD9731 chip 261_out) Pin number 12 (i.e., R) connected to AD9850 chip 231_setA pin).

The MCU22 is connected with the D0-D7 pins of the AD9850 chip 231. The MCU22 sends a trigger command including frequency configuration parameters to the AD9850 chip 231 based on the D0-D7 pins of the AD9850 chip 231. The MCU22 is connected to pins D0 to D9 of the AD9731 chip 261, and the MCU22 transmits a control command including current effective value configuration parameters to the AD9731 chip 261 based on the pins D0 to D9 of the AD9731 chip 261.

The AD9850 chip 231 generates an alternating current corresponding to the reception frequency configuration parameter contained in the trigger command, upon receiving the trigger command. After the AD9731 chip 261 receives the control command, it generates an amplitude-modulated current corresponding to the current effective value configuration parameter included in the control command, and transmits the amplitude-modulated current to the AD9850 chip 231 based on the connection between pin No. 20 of the AD9731 chip 261 and pin No. 12 of the AD9850 chip 231. The AD9850 chip 231 adjusts the amplitude of the ac current accordingly based on the amplitude-modulated current. The peripheral circuit 232 of the AD9850 chip 231 converts the ac current output by the AD9850 chip 231 into an ac voltage. The voltage-current conversion module 24 converts the ac voltage output by the peripheral circuit 232 of the AD9850 chip 231 into a current, which is a residual current. Finally, the voltage-current conversion module 24 outputs a residual current whose frequency corresponds to the frequency configuration parameter and whose effective current value corresponds to the effective current value configuration parameter. Furthermore, the residual current output by the voltage-current conversion module 24 is output to the outside through the current output module 25.

Based on the structure shown in fig. 3, the AD9850 chip 231 can generate a high-frequency alternating current. Also, the frequency of the alternating current output by the AD9850 chip 231 may be controlled by the MCU 22. The maximum value of the current signal output by the AD9850 chip 231 can reach 30 mA. In addition, the MCU22 can control the AD98731 chip 261 to adjust R of the AD9850 chip 231_setThe current magnitude of the pin, and thus the magnitude of the current signal output by the AD9850 chip 231.

A Liquid Crystal Display (LCD)29 may display the frequency configuration parameter and the current valid value configuration parameter to prompt the user for a specific value of the frequency and the valid value of the residual current.

In fig. 3, taking the AD9850 chip 231 outputting the peak current of 20mA as an example, the current passes through the 100 ohm (Ω) resistor to generate the voltage with a peak value of 2000mV, if the voltage-current conversion relationship of the voltage-current conversion module 24 is 1: 1, a current signal with a peak value of 2000mA is obtained, the effective value is 707mA, and the accuracy of the current output is 1/1023-0.1%.

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

Fig. 4 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 human-machine interface module (21) for receiving first configuration parameters;

The control module (22) is connected with the human-machine interface module (21) and is used for generating a trigger command containing the first configuration parameter;

A direct digital frequency synthesizer module (23) connected to the control module (22) for generating an alternating voltage based on the trigger command, the frequency of the alternating voltage corresponding to the first configuration parameter;

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

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

The human-machine interface module (21) is further used for receiving second configuration parameters; the control module (22) is further used for generating a control command containing the second configuration parameter;

The residual current generating device (20) further comprises:

An amplitude modulation module (26), connected to the control module (22) and the direct digital frequency synthesizer module (23), for generating an amplitude modulation signal corresponding to the second configuration parameter based on the control command, and sending the amplitude modulation signal to the direct digital frequency synthesizer module (23);

The direct digital frequency synthesizer module (23) is further configured to adjust the amplitude of the alternating voltage based on the amplitude modulation signal.

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

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

4. The residual current generating device (20) according to claim 2, characterized in that said amplitude modulation module (26) comprises a digital-to-analog converter.

5. The residual current generating device (20) according to any one of claims 1-4, wherein the control module (22) comprises a micro control unit, a central processing unit or a field programmable gate array.

6. The residual current generating device (20) according to any one of claims 1-4, wherein the human interface module (21) comprises a rotary encoder or a touch screen.

7. The residual current generating device (20) according to any one of claims 1 to 4, wherein said direct digital frequency synthesizer module (23) comprises: an AD9830 chip, an AD9831 chip, an AD9832 chip, an AD9833 chip, an AD9834 chip, an AD9835 chip, an AD9850 chip, an AD9851 chip, an AD9852 chip, an AD9853 chip, an AD9854 chip or an AD9858 chip.

8. The residual current generating device (20) according to claim 4, characterized in that said direct digital frequency synthesizer module (23) comprises an AD9850 chip (231) and said digital-to-analog converter comprises an AD9731 chip (261), wherein:

and the No. 20 pin of the AD9731 chip (261) is connected with the No. 12 pin of the AD9850 chip (231).

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