CN214335050U - Current sampling circuit - Google Patents
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- CN214335050U CN214335050U CN202023272922.8U CN202023272922U CN214335050U CN 214335050 U CN214335050 U CN 214335050U CN 202023272922 U CN202023272922 U CN 202023272922U CN 214335050 U CN214335050 U CN 214335050U
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Abstract
The embodiment of the utility model discloses a current sampling circuit, in the circuit, the input of first current sampling module and second current sampling module all receives the return circuit voltage signal, and the output of first current sampling module and second current sampling module is connected to processing module electricity respectively; after the first current sampling module is used for carrying out operation amplification on the loop voltage signal by m times, a first voltage signal which is allowed to be received by the processing module is obtained and is output to the processing module, and m is more than or equal to 1; after the second current sampling module is used for carrying out operation amplification on the loop voltage signal by mn times, a second voltage signal which is allowed to be received by the processing module is obtained and is output to the processing module, wherein n is greater than 1; the processing module calculates to obtain a first loop current according to the first voltage signal, calculates to obtain a second loop current according to the second voltage signal, and determines the second loop current as a target loop current if the first loop current is in a current sampling interval of the second current sampling module. The utility model discloses, high accuracy current sampling has been realized.
Description
Technical Field
The embodiment of the utility model provides a relate to the current detection technique, especially relate to a current sampling circuit.
Background
The motor is an essential component of most power equipment. In the control process of the motor, the collection of the three-phase current value is an important link in a motor control system, and the current sampling precision directly influences the control effect of the motor.
Normally, a hall current sensor is used for collecting a three-phase current value of a motor, the collected three-phase current value is output as a voltage signal, and the voltage signal is amplified by a signal amplifying circuit and then is transmitted to a processor chip for operation processing.
At present, when a current signal acquired by a Hall current sensor is tiny, the problem of insufficient sampling precision exists, and a great error exists between the operation result of a final processor chip and an actual numerical value.
SUMMERY OF THE UTILITY MODEL
An embodiment of the utility model provides a current sampling circuit to improve current sampling precision.
The embodiment of the utility model provides a current sampling circuit, include: the device comprises a first current sampling module, a second current sampling module and a processing module;
the input end of the first current sampling module and the input end of the second current sampling module both receive a loop voltage signal, and the output end of the first current sampling module and the output end of the second current sampling module are respectively and electrically connected to the processing module;
the first current sampling module is used for obtaining a first voltage signal which is allowed to be received by the processing module after the loop voltage signal is subjected to operation amplification by m times and outputting the first voltage signal to the processing module, wherein m is more than or equal to 1;
the second current sampling module is used for obtaining a second voltage signal which is allowed to be received by the processing module after the loop voltage signal is subjected to operation amplification mn times, and outputting the second voltage signal to the processing module, wherein n is greater than 1;
the processing module is used for calculating to obtain a first loop current according to the first voltage signal, calculating to obtain a second loop current according to the second voltage signal, and determining the second loop current as a target loop current if the first loop current is in a current sampling interval of the second current sampling module.
The embodiment of the utility model provides an in, the operational amplification of second circuit sampling module is the n times of the operational amplification of first current sampling module, is equivalent to carry out mn times to return circuit voltage signal and enlargies, so the precision after enlarging is more accurate than first current sampling module, is applicable to the undercurrent signal of sampling object equipment, and the less heavy current signal that first current sampling module of corresponding operational amplification is applicable to sampling object equipment. The processing module realizes signal sampling for amplifying m times through the first current sampling module, the processing module realizes signal sampling for amplifying mn times through the second current sampling module, then the current sampling circuit realizes signal sampling with different amplification factors, the different amplification factors can provide signals with different precisions, and the processing module determines the current signal of the object equipment according to the difference of sampling intervals to which the current signal obtained by calculation belongs, so that the current signal acquired by the current sampling circuit is more accurate, the error is reduced, and high-precision current sampling is realized.
Drawings
To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, a brief description will be given below of the drawings required for the embodiments or the technical solutions in the prior art, and it should be apparent that the drawings in the following description are some specific embodiments of the present invention, and it is obvious for those skilled in the art that the basic concepts of the device structure, the driving method and the manufacturing method disclosed and suggested according to the various embodiments of the present invention can be extended and extended to other structures and drawings, which should not be undoubted to be within the scope of the claims of the present invention.
Fig. 1 is a schematic diagram of a current sampling circuit according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of a first current sampling module;
FIG. 3 is a schematic diagram of a second current sampling module;
FIG. 4 is a circuit schematic of a first current sampling module;
fig. 5 is a circuit schematic of a second current sampling module.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be described clearly and completely through embodiments with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some embodiments of the present invention, not all embodiments. All other embodiments obtained by a person skilled in the art based on the basic concepts disclosed and suggested by the embodiments of the present invention belong to the protection scope of the present invention.
Referring to fig. 1, a schematic diagram of a current sampling circuit according to an embodiment of the present invention is shown. The current sampling circuit provided by the embodiment can be applied to any equipment for current sampling and detection.
The current sampling circuit provided by the embodiment comprises: the device comprises a first current sampling module 1, a second current sampling module 2 and a processing module 3; the input end of the first current sampling module 1 and the input end of the second current sampling module 2 both receive a loop voltage signal, and the output end of the first current sampling module 1 and the output end of the second current sampling module 2 are respectively and electrically connected to the processing module 3; the first current sampling module 1 is used for obtaining a first voltage signal which is allowed to be received by the processing module 3 after the loop voltage signal is subjected to operation amplification by m times, and outputting the first voltage signal to the processing module 3, wherein m is more than or equal to 1; the second current sampling module 2 is used for obtaining a second voltage signal which is allowed to be received by the processing module 3 after the loop voltage signal is subjected to operation amplification mn times, and outputting the second voltage signal to the processing module 3, wherein n is greater than 1; the processing module 3 is configured to calculate to obtain a first loop current according to the first voltage signal, calculate to obtain a second loop current according to the second voltage signal, and determine the second loop current as the target loop current if the first loop current is in the current sampling interval of the second current sampling module 2.
The selectable current sampling circuit further comprises: the output end of the current sensor 4 is respectively and electrically connected with the input end of the first current sampling module 1 and the input end of the second current sampling module 2; the current sensor 4 is used for collecting current signals in a loop where the current sensor is located and converting the current signals into loop voltage signals.
In this embodiment, the current sensor 4 collects a current signal in a loop where the current sensor is located, and converts the current signal into a voltage signal, where the voltage signal is a loop voltage signal input to the input end of the first current sampling module 1 and the input end of the second current sampling module 2. Optional current sensor 4 is arbitrary one kind current sensor such as hall sensor, the utility model discloses in not specifically inject. The optional current sensor 4 is used for collecting current signals in equipment or circuits such as motors and the like. For example, the hall sensor collects a current signal of the U-phase or W-phase of the motor, and converts the current signal into a loop voltage signal.
In this embodiment, the current sampling circuit includes a first current sampling module 1 and a second current sampling module 2, an input end of the first current sampling module 1 and an input end of the second current sampling module 2 receive the same loop voltage signal, and an output end of the first current sampling module 1 and an output end of the second current sampling module 2 are electrically connected to the processing module 3, respectively.
The first current sampling module 1 amplifies the loop voltage signal by m times in an operation way, and the second current sampling module 2 amplifies the loop voltage signal by mn times in an operation way, so that the operational amplification factors of the first current sampling module 1 and the second current sampling module 2 on the same loop voltage signal are different, and the operational amplification factor of the second current sampling module 2 is n times of the operational amplification factor of the first current sampling module 1. For example, if n is 4, the second current sampling module 2 amplifies the loop voltage signal by 4 times of the operational amplification of the first current sampling module 1; namely, the first current sampling module 1 amplifies the loop voltage signal by m times, and the second current sampling module 2 is equivalent to amplify all values of the loop voltage signal by 4 times on the basis of the first current sampling module 1.
The first current sampling module 1 receives a loop voltage signal, and after the loop voltage signal is operated and amplified by m times, the loop voltage signal is processed to obtain a first voltage signal which is allowed to be received by the processing module 3, and then the first voltage signal is output to the processing module 3, so that the processing module 3 receives the first voltage signal amplified by m times. The second current sampling module 2 receives the same loop voltage signal, and after the loop voltage signal is operated and amplified by mn times, the loop voltage signal is processed to obtain a second voltage signal which is allowed to be received by the processing module 3, and then the second voltage signal is output to the processing module 3, so that the processing module 3 receives the second voltage signal amplified by mn times.
The optional processing module 3 is a micro-control device such as an MCU or a singlechip, and the like, and the micro-control device has a standard level format, namely can only receive signals in the standard level format. For example, if the standard level format of the MCU is 0V to 3.3V, the voltage signal generated by the first current sampling module 1 exceeds the standard level format of the processing module 3, and only the processing module 3 can be provided with a 3.3V voltage signal, and the exceeded voltage is divided to ground; on the contrary, the voltage signal generated by the first current sampling module 1 conforms to the standard level format of the processing module 3, and the voltage signal generated by the first current sampling module 1 is directly input into the processing module 3, so that the first voltage signal is substantially the voltage signal generated by the first current sampling module 1 which conforms to the standard level format of the processing module 3. Similarly, the second voltage signal is a voltage signal generated by the second current sampling module 2 and conforming to the standard level format of the processing module 3. The processing module 3 receives the voltage signal in the standard level format, so that the processing module 3 can be protected from high voltage impact, and the performance and the service life of the processing module 3 are guaranteed.
Given that the second current sampling module 2 amplifies all values of the first current sampling module 1 by n times on the basis of the first current sampling module, and the first voltage signal and the second voltage signal received by the processing module 3 both conform to the standard level format of the processing module 3, when the loop voltage signal has a voltage sampling interval, the current calculated by the processing module 3 according to the first voltage signal necessarily has a first current sampling interval, the current calculated by the processing module 3 according to the second voltage signal necessarily has a second current sampling interval, and the first current sampling interval is n times of the second current sampling interval. For example, the first current sampling interval is [ -30A, +30A ], n is 4, and the second current sampling interval is [ -7.5A, +7.5A ].
The processing module 3 stores a second current sampling interval corresponding to the second current sampling module 2. It can be understood that, if the target device for current collection is different, the sampling interval of the loop voltage signal is different, for example, if the target device for current collection is a motor, the loop current signal generated by the motor is [ -30A, +30A ], and the sampling interval of the loop voltage signal converted by the current sensor is [ -4V, +4V ], which is an example and not limited thereto.
In addition, on the basis, the interval of the first loop current corresponding to the first voltage signal generated by the first current sampling module is [ -30A, +30A ]; the operational amplification factors of the second current sampling modules are different, the intervals of the second loop current corresponding to the second voltage signal generated by the second current sampling modules are also different, and the specific current sampling interval of the second current sampling module is 1/n of the current sampling interval of the first current sampling module. For example, if n is 4, the current sampling interval of the second current sampling module is [ -7.5A, +7.5A ]; and n is 6, the current sampling interval of the second current sampling module is [ -5A, +5A ].
When the current signal acquired by the current sensor 4 is located in the current sampling interval of the second current sampling module 2, the current signal representing the current moment of the object device is a small current signal. The voltage signal generated by the first current sampling module 1 based thereon and the voltage signal generated by the second current sampling module 2 based thereon both conform to the standard level format of the processing module 3. The processing module 3 receives the first voltage signal and the second voltage signal, calculates to obtain a first loop current according to the first voltage signal, and calculates to obtain a second loop current according to the second voltage signal. Obviously, the detected first loop current and second loop current are both in the current sampling interval corresponding to the second current sampling module 2, which indicates that the voltage signal output by the second current sampling module 2 is not divided to the ground, so that the second loop current of the second current sampling module 2 with a larger amplification factor can be used as the target loop current at the current moment, the sampling detection of the small current is realized, and the current sampling result is more accurate. The target loop current can be understood as the current signal of the sampled target device.
The optional processing module 3 is further configured to determine the first loop current as the target loop current when detecting that the first loop current exceeds the current sampling interval of the second current sampling module 2. When the current signal acquired by the current sensor 4 exceeds the current sampling interval of the second current sampling module 2, the current signal representing the current moment of the object device is a large current signal. The voltage signal generated by the first current sampling module 1 based on this meets the standard level format of the processing module 3, and the portion of the voltage signal generated by the second current sampling module 2 based on this, which exceeds the standard level format, is divided to ground. The processing module 3 receives a first voltage signal and a second voltage signal, wherein the second voltage signal is equal to 3.3V, calculates to obtain a first loop current according to the first voltage signal, and calculates to obtain a second loop current according to the second voltage signal. Obviously, the detected first loop current exceeds the current sampling interval corresponding to the second current sampling module 2, and the second loop current is equal to the limit value of the current sampling interval corresponding to the second current sampling module 2, which indicates that the voltage signal output by the second current sampling module 2 is divided, so that the first loop current of the first current sampling module 1 can be used as the target loop current at the current moment, and the sampling of the large current is realized.
In other embodiments, the processing module may be directly electrically connected to the motor for obtaining the rotation speed or the load of the motor.
Optionally, the target sampling module is switched by taking the rotation speed of the motor as a reference value, for example, a rotation speed threshold value is stored in the processing module, when the rotation speed of the motor detected by the processing module is less than or equal to the rotation speed threshold value, it is indicated that the current of the motor is small, the second current sampling module with a larger amplification factor can be directly determined as the target sampling module, the loop current is calculated according to the second voltage signal, and the obtained loop current is determined as the current of the motor; when the motor rotation speed detected by the processing module is greater than the rotation speed threshold, the motor current is larger, the first current sampling module can be directly determined as the target sampling module, the loop current is calculated according to the first voltage signal, and the obtained loop current is determined as the current of the motor. The operation steps are reduced.
Optionally, the target sampling module may be switched with the motor load as a reference value, for example, a load threshold is stored in the processing module, when the motor load detected by the processing module is less than or equal to the load threshold, it indicates that the motor current is small, the second current sampling module with a larger amplification factor may be directly determined as the target sampling module, the loop current is calculated according to the second voltage signal, and the obtained loop current is determined as the current of the motor; when the load of the motor detected by the processing module is greater than the load threshold, the current of the motor is larger, the first current sampling module can be directly determined as the target sampling module, the loop current is calculated according to the first voltage signal, and the obtained loop current is determined as the current of the motor. The operation steps are reduced.
In this embodiment, the operational amplification factor of the second circuit sampling module is n times of the operational amplification factor of the first current sampling module, which is equivalent to mn times of amplification of the loop voltage signal, so that the amplified precision is more accurate than that of the first current sampling module, and the second circuit sampling module is suitable for a small current signal of a sampling object device, and the corresponding first current sampling module with a smaller operational amplification factor is suitable for a large current signal of the sampling object device. The processing module realizes signal sampling for amplifying m times through the first current sampling module, the processing module realizes signal sampling for amplifying mn times through the second current sampling module, the current sampling circuit realizes signal sampling with different amplification factors, the different amplification factors can provide signals with different precision, and the processing module determines the current signal of the target device according to different sampling intervals to which the calculated current signal belongs. The current signal collected by the current sampling circuit is more accurate, the error is reduced, and high-precision current sampling is realized.
Illustratively, on the basis of the above technical solution, the optional first current sampling module shown in fig. 2 includes: a first operational amplification unit 11 and a first clamp unit 12; the input end of the first operational amplification unit 11 receives the loop voltage signal, and the output end of the first operational amplification unit 11 is connected in parallel with the first clamping unit 12 and then electrically connected to the processing module 3; after the loop voltage signal is amplified m times by the first operational amplification unit 11, the loop voltage signal is protected by the first clamping unit 12 to generate a first voltage signal which is allowed to be received by the processing module 3. The optional first current sampling module further comprises: a first filtering unit 13; the output end of the first operational amplification unit 11 is electrically connected to the first end of the first filtering unit 13, and the second end of the first filtering unit 13 is connected in parallel with the first clamping unit 12; after the loop voltage signal is subjected to operation amplification m times by the first operation amplification unit 11, the loop voltage signal is sequentially subjected to filtering by the first filtering unit 13 and clamping protection by the first clamping unit 12 to generate a first voltage signal which is allowed to be received by the processing module 3.
In this embodiment, the first operational amplifier unit 11 is configured to perform operational amplification on the received signal, specifically, after performing the operational amplification by m times, the signal is transmitted to the first clamping unit 12. The first clamping unit 12 is used for clamping and protecting the received signal. Given that the processing module 3 has a standard level format, the first clamping unit 12 is mainly used for clamping the received signal to conform to the standard level format of the processing module 3, so as to divide the excessive voltage signal to the ground. For example, the processing module 3 is an MCU, and its standard level format is not more than 3.3V; when the signal output by the first operational amplification unit 11 does not exceed 3.3V, the signal may directly enter the processing module 3 through the first clamping unit 12, and when the signal (e.g. 5V) output by the first operational amplification unit 11 is greater than 3.3V, the excess voltage signal (1.7V — 5V — 3.3V) flows to the ground through the first clamping unit 12, and only 3.3V enters the processing module 3. The processing module 3 can thus be protected.
The first filtering unit 13 is further disposed before the first clamping unit 12, and the first filtering unit 13 is configured to perform low-pass filtering processing on the signal output by the first operational amplifying unit 11, so that the low-frequency signal can normally pass through, and the high-frequency signal is blocked and weakened, thereby further limiting the signal entering the first clamping unit 12, and improving the accuracy of the output current of the first current sampling module 1.
An alternative second current sampling module, as shown in fig. 3, includes: a second operational amplification unit 21, a current limiting unit 22, a voltage following unit 23, and a second clamping unit 24; the input end of the second operational amplification unit 21 receives the loop voltage signal, the current limiting unit 22 is coupled between the output end of the second operational amplification unit 21 and the input end of the voltage following unit 23, and the output end of the voltage following unit 23 is connected in parallel with the second clamping unit 24 and then electrically connected to the processing module 3; after the loop voltage signal is subjected to mn times of operational amplification by the second operational amplification unit 21, the loop voltage signal is subjected to current limiting by the current limiting unit 22, shaping by the voltage following unit 23, and clamp protection by the second clamping unit 24 to generate a second voltage signal which is allowed to be received by the processing module 3.
The optional second current sampling module further comprises: a second filtering unit 25; the output end of the voltage following unit 23 is electrically connected to the first end of the second filtering unit 25, and the second end of the second filtering unit 25 is connected in parallel with the second clamping unit 24; after the loop voltage signal is subjected to mn times of operational amplification by the second operational amplification unit 21, the loop voltage signal is subjected to current limiting by the current limiting unit 22, shaping by the voltage following unit 23, filtering by the second filtering unit 25 and clamp protection by the second clamping unit 24 to generate a second voltage signal which is allowed to be received by the processing module 3.
The optional voltage following unit 23 includes a clamp diode and an operational amplifier; the first terminal of the clamping diode and the input terminal of the operational amplifier are electrically connected to the current limiting unit 22, and the output terminal of the operational amplifier is electrically connected to the first terminal of the second filtering unit 25.
In this embodiment, the second operational amplifier unit 21 is configured to perform operational amplification on the received signal, specifically, to perform the operational amplification by mn times, and then transmit the signal to the current limiting unit 22. The current limiting unit 22 is used for limiting the received signal, so that the voltage amplitude of the received signal is unchanged, but the current is greatly reduced. The voltage following unit 23 is used for reprocessing the received current, shaping the waveform, and the like, so that the stability of the signal is improved, low-resistance output can be realized, and the output and a post-stage circuit cannot be influenced mutually. The second clamping unit 24 is used for clamping and protecting the received signal. Given that the processing module 3 has a standard level format, the second clamping unit 24 is mainly used for clamping the received signal to conform to the standard level format of the processing module 3, so as to divide the excessive voltage signal to the ground. For example, the processing module 3 is an MCU, and its standard level format is not more than 3.3V; when the signal passing through the second clamping unit 24 does not exceed 3.3V, the signal enters the processing module 3, and when the signal (for example, 12V) passing through the second clamping unit 24 is greater than 3.3V, the excess voltage signal (8.7V — 12V — 3.3V) flows to the ground through the second clamping unit 24, and only 3.3V enters the processing module 3. The processing module 3 can thus be protected.
The second filtering unit 25 is further disposed behind the voltage following unit 23, and the second filtering unit 25 is configured to perform low-pass filtering processing on the received signal, so that the low-frequency signal can normally pass through, and the high-frequency signal is blocked and weakened, thereby further limiting the signal entering the second clamping unit 24, and improving the accuracy of the output current of the second current sampling module 2.
It can be understood that after the processing module calculates the target loop current, the processing module may determine the next control on the target device, such as a motor, according to the target loop current, and the specific implementation manner is not described herein again.
The embodiment of the utility model provides an in, different multiples can be enlargied to the current sampling circuit, including m times and nm times. When the signal output by the current sensor is tiny, the processing module can adopt the signal of the second current sampling module with larger amplification factor to carry out current operation; when the signal output by the current sensor is large, the processing module can perform current operation by using the signal of the first current sampling module with a small amplification factor. This current sampling circuit, the combination of accurate sampling and rough sampling, processing module are according to the big dynamic switching of electric current size for the magnification is always in best work area, has improved the sampling result degree of accuracy of the electric current signal of equidimension not, reduces the signal that electric current sampling module received and the error of the data that processing module calculated, realizes the high accuracy sampling of the electric current signal of equidimension not. In addition, the current sampling circuit adopts low-price devices, can realize high-precision current sampling by adopting a simple structure and operation logic, and reduces the production cost.
On this basis, the embodiment of the utility model provides a current sampling circuit.
As shown in fig. 4, the first current sampling module in the current sampling circuit includes a first operational amplifier unit 11, a first filter unit 13, and a first clamping unit 12, and the output first voltage signal U-a conforms to the standard level format of the processing module. The specific circuit structure and device connection mode of each unit are shown in fig. 4, and are not described in detail here.
The second current sampling module in the current sampling circuit is shown in fig. 5, and includes a second operational amplifying unit 21, a current limiting unit 22, a voltage following unit 23, a second filtering unit 25, and a second clamping unit 24, and a second voltage signal U-B output by the second operational amplifying unit meets the definition of the standard level format of the processing module. The specific circuit structure and device connection manner of each unit are shown in fig. 5, and are not described in detail here.
The first current sampling module is responsible for conventional sampling of large current signals, and the second current sampling module is responsible for sampling of small current signals.
The target equipment of the selectable current sampling circuit is a motor, the current sensor is a Hall sensor, the processing module is an MUC, the standard level format of the MUC is 0-3.3V, and the reference voltage of the current sampling circuit is 1.65V. The upper limit of the actual working current of the motor is +30A, the lower limit of the actual working current of the motor is-30A, and the upper limit of the voltage output by the Hall sensor is +4V and the lower limit of the voltage output by the Hall sensor is-4V. The loop voltage signals received by the first current sampling module and the second current sampling module are within the range of [ -4V, +4V ], that is, the IU + upper limit is +4V, and the IU-lower limit is-4V. Optionally, m is 3.3/8 and n is 4.
Referring to fig. 4, the first current sampling module amplifies [ -4V, +4V ] by 3.3/8 times, so that the upper voltage limit of the output terminal U-a is (3.3/8) ± (+4V) +1.65V ═ 3.3V, and the lower voltage limit of U-a is (3.3/8) (-4V) +1.65V ═ 0V, so that after amplifying by m times, the first current sampling module converts [ -4V, +4V ] into [0V, +3.3V ] and outputs the converted value. Wherein, the output end of the first operational amplification unit 11 is 0-3.3V, and then is filtered by the first filtering unit 13, and the first clamping unit 12 clamps for protection, the voltage interval of the output end U-A is limited to [0V, +3.3V ], and the sampled current range is-30A- + 30A. It can be understood that the amplification factor of the first operational amplifier unit 11 is mainly determined by the ratio of the resistances of R146 and R144.
Referring to fig. 5, the second current sampling module amplifies [ -4V, +4V ] by 3.3/2 times, it should be ensured that the upper voltage limit of the output terminal U-B is 3.3V, and the lower voltage limit of U-B is 0V, knowing that the reference voltage is 1.65V, then obtains U-B + (3.3/2) (+ 1.65V) +3.3V, and U-B- (3.3/2) (-1V) +1.65V ═ 0V, and after amplifying mn times, the second current sampling module amplifies [ -1V, +1V ] by 3.3/2 times, and then converts to [0V, +3.3V ] for output. The output end of the second operational amplification unit 21 is 0-13.2V, the current energy is greatly weakened through the current limiting resistor R160, the voltage is unchanged, the clamping diode in the voltage following unit 23 clamps and protects [0, 13.2V ] at [0V, +3.3V ], the two-stage operational amplifier is operated and then outputs, the two-stage operational amplifier sequentially passes through the filtering of the second filtering unit 25 and the clamping protection of the second clamping unit 24, the voltage interval of the output end U-B is limited to [0V, +3.3V ], and the sampled current range is-7.5A- + 7.5A. It is understood that the amplification factor of the second operational amplifier unit 21 is mainly determined by the ratio of the resistances of R156 and R154.
The optional current limiting unit 22 is a current limiting resistor R160, and the resistance value of the current limiting resistor is 1K Ω -10K Ω, so that the current can be greatly weakened and the voltage can be ensured to be unchanged. The optional clamping unit comprises a clamping diode, the clamping diode selects a 3.3V voltage regulator, and once voltage exceeding 3.3V flows through the clamping diode, the clamping diode is conducted to the ground in a reverse direction, so that the processing module is protected from being impacted and damaged.
It is to be understood that the above-provided current sampling circuit is merely an example, and the selection of device parameters and the like may be adjusted according to different target devices or different loop voltage signals, and is not limited thereto.
As described above, the signal collected by the second current sampling module is 1/n of the signal collected by the first current sampling module, so the accuracy of amplifying the small current by the second current sampling module is better than that of the first current sampling module, and the accuracy of detecting the small current is correspondingly higher.
The current rated range of the motor is known to be-30A- +30A, the current is 0A when the motor stops working, and the current can flutter in a small range from 0A up to down under the condition of light load or low rotating speed of the motor. The voltage signal output by the first current sampling module is adopted to carry out current operation in the range from 7.5A to 30A and the range from-7.5A to-30A with large amplitude, so that the large current sampling error can be reduced, and the sampling precision is improved. In the range from-7.5A to +7.5A with small amplitude, the second current sampling module with higher amplification factor is adopted to amplify all the numerical values of the first current sampling module by n times, and the processing module carries out current operation according to the voltage signal output by the processing module, so that the small current sampling detection error can be reduced, and the sampling detection precision is improved.
It should be noted that the foregoing is only a preferred embodiment of the present invention and the technical principles applied. It will be understood by those skilled in the art that the present invention is not limited to the particular embodiments described herein, but is capable of various obvious modifications, rearrangements, combinations and substitutions as will now become apparent to those skilled in the art without departing from the scope of the invention. Therefore, although the present invention has been described in greater detail with reference to the above embodiments, the present invention is not limited to the above embodiments, and may include other equivalent embodiments without departing from the scope of the present invention.
Claims (9)
1. A current sampling circuit, comprising: the device comprises a first current sampling module, a second current sampling module and a processing module;
the input end of the first current sampling module and the input end of the second current sampling module both receive a loop voltage signal, and the output end of the first current sampling module and the output end of the second current sampling module are respectively and electrically connected to the processing module;
the first current sampling module is used for obtaining a first voltage signal which is allowed to be received by the processing module after the loop voltage signal is subjected to operation amplification by m times and outputting the first voltage signal to the processing module, wherein m is more than or equal to 1;
the second current sampling module is used for obtaining a second voltage signal which is allowed to be received by the processing module after the loop voltage signal is subjected to operation amplification mn times, and outputting the second voltage signal to the processing module, wherein n is greater than 1;
the processing module is used for calculating to obtain a first loop current according to the first voltage signal, calculating to obtain a second loop current according to the second voltage signal, and determining the second loop current as a target loop current if the first loop current is in a current sampling interval of the second current sampling module.
2. The current sampling circuit of claim 1, wherein the processing module is further configured to determine the first loop current as a target loop current upon detecting that the first loop current exceeds a current sampling interval of the second current sampling module.
3. The current sampling circuit of claim 1, wherein the first current sampling module comprises: a first operational amplification unit and a first clamping unit;
the input end of the first operational amplification unit receives the loop voltage signal, and the output end of the first operational amplification unit is connected with the first clamping unit in parallel and then electrically connected to the processing module;
after the loop voltage signal is subjected to operation amplification m times by the first operation amplification unit, the loop voltage signal is subjected to clamp protection by the first clamping unit to generate a first voltage signal which is allowed to be received by the processing module.
4. The current sampling circuit of claim 3, wherein the first current sampling module further comprises: a first filtering unit;
the output end of the first operational amplification unit is electrically connected to the first end of the first filtering unit, and the second end of the first filtering unit is connected with the first clamping unit in parallel;
after the loop voltage signal is subjected to operation amplification m times by the first operation amplification unit, the loop voltage signal is subjected to filtering by the first filtering unit and clamping protection by the first clamping unit in sequence to generate a first voltage signal which is allowed to be received by the processing module.
5. The current sampling circuit of claim 1, wherein the second current sampling module comprises: the second operational amplification unit, the current limiting unit, the voltage following unit and the second clamping unit;
the input end of the second operational amplification unit receives the loop voltage signal, the current limiting unit is coupled between the output end of the second operational amplification unit and the input end of the voltage following unit, and the output end of the voltage following unit and the second clamping unit are connected in parallel and then electrically connected to the processing module;
after the loop voltage signal is subjected to mn-fold operational amplification by the second operational amplification unit, the loop voltage signal is subjected to current limiting by the current limiting unit, shaping by the voltage following unit and clamping protection by the second clamping unit in sequence to generate a second voltage signal which is allowed to be received by the processing module.
6. The current sampling circuit of claim 5, wherein the second current sampling module further comprises: a second filtering unit;
the output end of the voltage following unit is electrically connected to the first end of the second filtering unit, and the second end of the second filtering unit is connected in parallel with the second clamping unit;
after the loop voltage signal is subjected to mn-fold operational amplification by the second operational amplification unit, the loop voltage signal sequentially passes through the current limiting unit to limit current, the voltage following unit to shape, the second filtering unit to filter and the second clamping unit to clamp and protect, and then a second voltage signal which is allowed to be received by the processing module is generated.
7. The current sampling circuit of claim 6, wherein the voltage follower unit comprises a clamping diode and an operational amplifier;
the first end of the clamping diode and the input end of the operational amplifier are both electrically connected with the current limiting unit, and the output end of the operational amplifier is electrically connected with the first end of the second filtering unit.
8. The current sampling circuit of claim 5, wherein the current limiting unit is a current limiting resistor having a resistance of 1K Ω -10K Ω.
9. The current sampling circuit of claim 1, further comprising: the output end of the current sensor is electrically connected with the input end of the first current sampling module and the input end of the second current sampling module respectively;
the current sensor is used for collecting current signals in a loop where the current sensor is located and converting the current signals into loop voltage signals.
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| CN112630504A (en) * | 2020-12-30 | 2021-04-09 | 广东拓斯达科技股份有限公司 | Current sampling circuit |
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| CN112630504A (en) * | 2020-12-30 | 2021-04-09 | 广东拓斯达科技股份有限公司 | Current sampling circuit |
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