CN113804957A - Current sampling circuit and protection device - Google Patents
Current sampling circuit and protection device Download PDFInfo
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- CN113804957A CN113804957A CN202111101086.3A CN202111101086A CN113804957A CN 113804957 A CN113804957 A CN 113804957A CN 202111101086 A CN202111101086 A CN 202111101086A CN 113804957 A CN113804957 A CN 113804957A
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- 238000005070 sampling Methods 0.000 title claims abstract description 213
- 238000001514 detection method Methods 0.000 claims description 18
- 230000002159 abnormal effect Effects 0.000 claims description 6
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- 230000000712 assembly Effects 0.000 claims description 4
- 238000000429 assembly Methods 0.000 claims description 4
- 230000001681 protective effect Effects 0.000 claims 1
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- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
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- 238000004891 communication Methods 0.000 description 1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
- G01R19/25—Arrangements for measuring currents or voltages or for indicating presence or sign thereof using digital measurement techniques
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Abstract
The invention discloses a current sampling circuit and a protection device, wherein the circuit is provided with a plurality of current sampling branches arranged between a direct current input end and a direct current output end, each current sampling branch corresponds to a sampling range, and the sampling ranges of the current sampling branches form a continuous sampling range and a continuous current range; meanwhile, in order to ensure the reliability of the sampling circuit, the switch assembly is controlled by the control module, so that the plurality of current sampling branches are sequentially conducted according to the sequence from large current to small current until the sampling value of the input current is suitable for the corresponding sampling range of the conducted current sampling branch. Therefore, the invention can automatically judge the magnitude of the input current and automatically switch to a proper sampling current interval for current sampling, thereby improving the sampling precision and widening the application scene adapted by the sampling circuit.
Description
Technical Field
The invention relates to the technical field of current sampling, in particular to a current sampling circuit and a protection device.
Background
The existing current sampling circuit generally has limitations, for example, for a circuit meeting the sampling precision requirement of small current, the existing current sampling circuit cannot sample large current; for a circuit meeting the requirement of high-current sampling precision, the low-current sampling precision is insufficient, that is, the current and precision sampling requirements of various application scenes cannot be met simultaneously.
Therefore, it is necessary to provide a current sampling scheme that combines sampling precision and current sampling range.
Disclosure of Invention
The invention aims to overcome the defect that the current sampling circuit in the prior art cannot meet the requirements of multi-interval current and precision, and provides a wide-range current sampling circuit which can automatically identify the magnitude of input current and automatically switch to a proper sampling current interval for current sampling, thereby improving the sampling precision.
In order to achieve the purpose, the invention provides the following technical scheme:
a current sampling circuit, comprising:
a control module;
a switch assembly; the sampling device comprises a direct current input end, a direct current output end, a plurality of current sampling branches and a plurality of sampling units, wherein the plurality of current sampling branches are arranged between the direct current input end and the direct current output end, each current sampling branch corresponds to a sampling range, and the sampling ranges of the plurality of current sampling branches form a continuous sampling range;
and the control module is configured to sequentially conduct the current sampling branches to the corresponding current sampling branches according to a sequence from a large current to a small current by controlling the switch assembly until the sampling value of the input current meets the corresponding sampling range of the conducted current sampling branches.
According to a specific embodiment, in the current sampling circuit of the present invention, the current sampling branch includes: the current sampling resistor and the current detection chip are connected with the current sampling resistor; the current detection chip is connected with the control module and used for transmitting a current sampling signal detected by the current detection chip to the control module; and the control module is used for obtaining a sampling value of the input current according to the current sampling signal.
Further, the current sampling branch further comprises: and one or more voltage division circuits connected with the current sampling resistor.
According to a specific implementation manner, in the current sampling circuit of the present invention, the control module is configured with a trigger interface for acquiring an external pulse signal; and the control module is configured to synchronously control the switch assemblies according to an external pulse signal, so that the corresponding current sampling branch circuit performs current sampling.
Further, the control module stores periodic data of one or more pulse signals; and the control module is configured to synchronously control the switch assemblies according to the period data of the pulse signals, so that the corresponding current sampling branches sample the input current.
Still further, the control module is configured to start the corresponding current sampling branch to perform current sampling when the pulse signal is at a high level, and stop current sampling of the current sampling branch when the pulse signal is at a low level.
Therefore, the control module is subjected to sampling trigger setting based on the external pulse, so that the control module obtains current sampling data in the effective pulse signal in a corresponding working state based on the pulse signal.
According to a specific embodiment, in the current sampling circuit of the present invention, the control module is configured to synchronously sample the input current according to an external pulse signal or periodic data of the pulse signal, and the sampling time of the current is a single effective pulse width time plus or minus a single effective pulse width time by a preset percentage.
In this embodiment, the preset percentage may be set according to the circuit requirement, and taking the single pulse width as 10mS and the preset percentage as 5% as an example, the sampling time is 0.5mS to 9.5 mS.
According to a specific embodiment, in the current sampling circuit of the present invention, the switch module includes: a plurality of pairs of switching elements; wherein each pair of switching elements corresponds to one current sampling branch respectively.
Further, each pair of switching elements includes: an MOS tube and a relay; and the control module controls the on-off of the relay through the MOS tube to realize the conduction control of the corresponding current sampling branch.
In a further embodiment of the present invention, there is also provided a protection device, including: the current sampling circuit and a hardware protection circuit connected with the current sampling circuit;
the hardware protection circuit is connected with the control module and used for obtaining a sampling value of input current and comparing the sampling value with a preset reference value to determine whether the input current is abnormal, and if the input current is determined to be abnormal, control voltage is output to the relay to control the on-off of the relay so as to realize the on-off control of the corresponding current sampling branch.
Compared with the prior art, the invention has the beneficial effects that:
1. the wide-range current sampling circuit comprises a plurality of current sampling branches arranged between a direct current input end and a direct current output end, wherein each current sampling branch corresponds to a sampling range, and the sampling ranges of the current sampling branches form a continuous sampling range; and the control module controls the switch assembly to enable the plurality of current sampling branches to be sequentially conducted according to the sequence from large current to small current until the sampling value of the input current is suitable for the corresponding sampling range of the conducted current sampling branch. Therefore, the invention can input the current and automatically switch to a proper sampling current interval to sample the current, thereby improving the sampling precision.
2. According to the wide-range current sampling circuit, the control module can synchronously sample the input current according to the external pulse signal or the periodic data of the pulse signal, so that current collection in any period is realized; in addition, the effective value taking time of the input current sampling value is set, so that the time delay influence of the pulse signal is reduced, the sampling value of the input current is more accurate, and the occurrence of false alarm and false protection is prevented.
Drawings
FIG. 1 is a circuit block diagram of a wide range current sampling circuit of the present invention;
FIG. 2 is a circuit diagram of the wide range current sampling circuit of the present invention including a pulse trigger function;
FIG. 3 is a schematic waveform diagram of a pulse signal;
fig. 4 is a circuit diagram of a wide range current sampling circuit incorporating pulse triggering and hardware protection functions in accordance with the present invention.
Detailed Description
The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention.
The wide range current sampling circuit of the present invention comprises:
a control module;
a switch assembly; the sampling device comprises a direct current input end, a direct current output end, a plurality of current sampling branches and a plurality of sampling units, wherein the plurality of current sampling branches are arranged between the direct current input end and the direct current output end, each current sampling branch corresponds to a sampling range, and the sampling ranges of the plurality of current sampling branches form a continuous sampling range;
and the control module is configured to sequentially conduct the current sampling branches to the corresponding current sampling branches according to a sequence from a large current to a small current by controlling the switch assembly until the sampling value of the input current meets the corresponding sampling range of the conducted current sampling branches.
As shown in fig. 1, the wide-range current sampling circuit of the present invention has two current sampling branches, the control module adopts an MCU, and the switch assembly includes two MOS transistors and two relays K1 and K2.
Specifically, the current sampling branch includes: the current sampling resistor and the current detection chip are connected with the current sampling resistor; the current detection chip is connected with the control module and used for transmitting a current sampling signal detected by the current detection chip to the control module; and the control module is used for obtaining a sampling value of the input current according to the current sampling signal.
In the implementation process, the current detection chip 1 has a circuit detection range of 0.005-10A @5mA precision; the circuit detection range of the current detection chip 2 is 10-400A @0.1A in precision. When a circuit is designed, the size and the power specification of a current sampling resistance value need to be reasonably selected, the output voltage of a current detection chip is ensured to meet the specification of the current detection chip, and meanwhile, whether the maximum working current meets the power derating of the current sampling resistance or not needs to be calculated. When the output voltage of the current detection chip exceeds the DAC sampling range, a voltage division circuit can be added at the sampling voltage input end to realize the purpose of ensuring effective precision sampling and adjustment.
And the MCU program respectively sets the upper limit output voltage range interval and the lower limit output voltage range interval of each current sampling branch. And preferentially switching on the maximum current sampling branch, and if the corresponding voltage of the sampling current exceeds the upper limit of the branch, switching off the switches K1 and K2, so that the circuit does not work. If the sampling current corresponding voltage is smaller than the lower limit voltage of the branch circuit, the current sampling branch circuit is switched to the next stage sampling interval, and the current is prevented from exceeding the derating and damaging branch circuit components. And the automatic selection of the proper sampling unit according to different current sizes is realized.
For example, taking current sampling of a high-power rf circuit as an example, the high-power rf circuit generally consists of a plurality of PAs, and when a static operating point is set for a PA, the current generally varies from tens of milliamperes to hundreds of milliamperes, and in order to ensure the optimal static operating point, the accuracy control range is often within 10 mA. And when the single PA works at the actual rated power, the peak power of the single PA can reach dozens of amperes. For radio frequency modules with KW level and above, the radio frequency modules are composed of a plurality of PAs, and the total current can reach hundreds of amperes. The wide-range current sampling circuit can completely meet the requirements.
For another example, for devices operating at peaks and valleys, the power consumption of the devices is different according to different periods and different traffic volumes. If the working current is required to be detected with high precision in real time, the wide-range current sampling circuit can freely switch the precision of the sampling circuit according to the working current so as to meet the detection requirement.
As shown in fig. 2, in the wide-range current sampling circuit of the present invention, the MCU adopted by the control module is configured with a trigger interface for acquiring an external pulse signal, so that the sampling compatibility between the continuous operation mode and the pulse operation mode of the product can be realized. At this time, the control module triggers the current sampling branch circuit to sample the input current according to the high-low level state of the external pulse signal. In addition, the control module can also store periodic sampling data of one or more pulse signals for reporting or external communication inquiry.
For example, for the current sampling of the MRI power amplifier, because the MRI power amplifier belongs to a non-continuously working amplifier, the working current in the pulse signal period can be sampled and alarmed synchronously through the triggering of the pulse signal. By adopting the wide-range current sampling circuit, the problem that the traditional continuous sampling mode acquires current data in a non-working mode in a pulse period to cause false alarm and false protection can be avoided.
With reference to the pulse signal shown in fig. 3, wherein TU: working pulse on time; TR: total time of a single duty cycle; tblank: TR-TU is the off time in a single cycle. Except that a hardware circuit is based on a conventional sampling circuit, an external trigger interface is added through the MCU, so that the period of a synchronous pulse signal is consistent with the sampling and control time; in a software layer, the MCU adopted by the control module is configured to acquire the data acquisition of the corresponding current sampling branch when the pulse signal is at a high level, and to stop the data acquisition of the corresponding current sampling branch when the pulse signal is at a low level. That is, when the received trigger signal is at a high level, current detection sampling and data uploading are started, and when the trigger signal is at a low level, information and data sampling are stopped.
In an implementation, in consideration of the time delay effect of the pulse signal, in the wide-range current sampling circuit of the present invention, the control module is configured to, when the input current is synchronously sampled according to the external pulse signal or the period data of the pulse signal, sample time of the current is a single effective pulse width time plus or minus a single effective pulse width time 5%. For example, the single pulse width is 10mS, that is, the sampling time is 0.5mS to 9.5 mS. Therefore, by setting the effective value taking time of the input current sampling value, the time delay influence of the pulse signal is reduced, the sampling value of the input current is more accurate, and the occurrence of false alarm and false protection is prevented.
In one embodiment, the wide range current sampling circuit of the present invention further comprises: a hardware protection circuit; and the hardware protection circuit is connected with the control module and used for acquiring a sampling value of the input current and comparing the sampling value with a reference value to determine whether the input current is abnormal, and if the input current is determined to be abnormal, the hardware protection circuit outputs control voltage to the relay to control the on-off of the relay so as to realize the conduction control of the corresponding current sampling branch circuit.
Specifically, as shown in fig. 4, the hardware protection function of the wide-range current sampling circuit of the present invention compares the output voltage of the I/O port of the MCU with the reference voltage of the comparator, so that the output voltage of the comparator is inverted, and then outputs a control voltage to the relay, so as to control the on/off of the relays K1 and K2, thereby implementing the on control of the corresponding current sampling branch.
In one embodiment, the wide range current sampling circuit of the present invention may also provide a log monitoring function; specifically, assuming that the effective sampling frequency is preset to be 0.1ms, 10 sampling periods are averaged to serve as one report point, and 20 report points before the current time are stored, that is, (20ms) is used as a sampling monitoring data log (the specific values of the storage point and the sampling frequency are adjusted according to the actual effect). The log may provide for host queries, automatic iterative refreshing of information beyond storage capacity. And the log information can be actively sent out at fixed time for backup.
In another embodiment, the wide range current sampling circuit of the present invention may also provide temperature compensation functionality; specifically, the chip current sampling chip individual difference is added with the sampling deviation at different temperatures. In order to ensure sampling accuracy, the current at different temperatures needs to be sampled, an offset calculation is performed on the current and the actual current, an error is written into a program, and the correction is performed according to the sampling value at the corresponding temperature during actual operation.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.
Claims (10)
1. A current sampling circuit, comprising:
a control module;
a switch assembly; the current sampling branch circuits are arranged between the direct current input end and the direct current output end, each current sampling branch circuit corresponds to a sampling range and a current range, and the sampling ranges of the current sampling branch circuits form a continuous sampling range;
and the control module is configured to sequentially conduct the current sampling branches to the corresponding current sampling branches according to a sequence from a large current to a small current by controlling the switch assembly until the sampling value of the input current meets the corresponding sampling range of the conducted current sampling branches.
2. The current sampling circuit of claim 1, wherein the current sampling branch comprises: the current sampling resistor and the current detection chip are connected with the current sampling resistor; the current detection chip is connected with the control module and used for transmitting a current sampling signal detected by the current detection chip to the control module; and the control module is used for obtaining a sampling value of the input current according to the current sampling signal.
3. The current sampling circuit of claim 2, wherein the current sampling branch further comprises: and one or more voltage division circuits connected with the current sampling resistor.
4. The current sampling circuit according to any one of claims 1 to 3, wherein the control module is configured with a trigger interface for acquiring an external pulse signal; and the control module is configured to synchronously control the switch assemblies according to an external pulse signal, so that the corresponding current sampling branch circuit performs current sampling.
5. The current sampling circuit of claim 4, wherein the control module stores periodic data of one or more pulse signals; and the control module is configured to synchronously control the switch assemblies according to the period data of the pulse signals, so that the corresponding current sampling branches sample the input current.
6. The current sampling circuit of claim 5, wherein the control module is configured to enable the corresponding current sampling branch to perform current sampling when the pulse signal is high, and to disable current sampling of the current sampling branch when the pulse signal is low.
7. The current sampling circuit of claim 6, wherein the control module is configured to synchronously sample the input current according to an external pulse signal or periodic data of the pulse signal, and the sampling time of the current is a single effective pulse width time plus or minus a preset percentage of the single effective pulse width time.
8. The current sampling circuit of any of claims 1-3, wherein the switching assembly comprises: a plurality of pairs of switching elements; wherein each pair of switching elements corresponds to one current sampling branch respectively.
9. The current sampling circuit of claim 8, wherein each pair of switching elements comprises: an MOS tube and a relay; and the control module controls the on-off of the relay through the MOS tube to realize the conduction control of the corresponding current sampling branch.
10. A protective device, comprising: the current sampling circuit of any of claims 1-9, and a hardware protection circuit coupled to the current sampling circuit;
the hardware protection circuit is connected with the control module and used for obtaining a sampling value of input current and comparing the sampling value with a preset reference value to determine whether the input current is abnormal, and if the input current is determined to be abnormal, control voltage is output to the relay to control the on-off of the relay so as to realize the on-off control of the corresponding current sampling branch.
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| CN202111101086.3A CN113804957A (en) | 2021-09-18 | 2021-09-18 | Current sampling circuit and protection device |
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| CN202111101086.3A CN113804957A (en) | 2021-09-18 | 2021-09-18 | Current sampling circuit and protection device |
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| JP2004077743A (en) * | 2002-08-16 | 2004-03-11 | Sony Corp | Current sampling circuit and current output type drive circuit using the same |
| CN206489213U (en) * | 2016-12-23 | 2017-09-12 | 芜湖国睿兆伏电子有限公司 | A kind of pulse current sample circuit |
| CA3033673A1 (en) * | 2018-02-28 | 2019-08-28 | Esab Ab | Arc voltage sensing and control for a welding apparatus |
| CN110350485A (en) * | 2019-07-12 | 2019-10-18 | 四川虹美智能科技有限公司 | A kind of overcurrent protection module, system and method |
| CN111179842A (en) * | 2020-03-12 | 2020-05-19 | 京东方科技集团股份有限公司 | Compensation circuit, display module and driving method thereof |
| CN111665380A (en) * | 2020-06-08 | 2020-09-15 | 珠海格力电器股份有限公司 | Current sampling device, system and method |
-
2021
- 2021-09-18 CN CN202111101086.3A patent/CN113804957A/en active Pending
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2004077743A (en) * | 2002-08-16 | 2004-03-11 | Sony Corp | Current sampling circuit and current output type drive circuit using the same |
| CN206489213U (en) * | 2016-12-23 | 2017-09-12 | 芜湖国睿兆伏电子有限公司 | A kind of pulse current sample circuit |
| CA3033673A1 (en) * | 2018-02-28 | 2019-08-28 | Esab Ab | Arc voltage sensing and control for a welding apparatus |
| CN110350485A (en) * | 2019-07-12 | 2019-10-18 | 四川虹美智能科技有限公司 | A kind of overcurrent protection module, system and method |
| CN111179842A (en) * | 2020-03-12 | 2020-05-19 | 京东方科技集团股份有限公司 | Compensation circuit, display module and driving method thereof |
| CN111665380A (en) * | 2020-06-08 | 2020-09-15 | 珠海格力电器股份有限公司 | Current sampling device, system and method |
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