A current sampling circuit

Abstract

The embodiment of the present invention discloses a current sampling circuit, in which the input ends of the first current sampling module and the second current sampling module both receive loop voltage signals, and the output ends of the first current sampling module and the second current sampling module are respectively electrically connected to the processing module; the first current sampling module amplifies the loop voltage signal by m times, obtains the first voltage signal that the processing module allows to receive and outputs it to the processing module, m≥1; the second current sampling module amplifies the loop voltage signal by mn times, obtains the second voltage signal that the processing module allows to receive and outputs it to the processing module, n>1; the processing module calculates the first loop current according to the first voltage signal, and calculates the second loop current according to the second voltage signal, and if the first loop current is in the current sampling interval of the second current sampling module, the second loop current is determined as the target loop current. The embodiment of the present invention realizes high-precision current sampling.

Description

Technical Field

[0001] The embodiments of the present invention relate to current detection technology, and in particular to a current sampling circuit. Background Art

[0002] Motors are essential components of most power equipment. In the process of motor control, the acquisition of three-phase current values ​​is a very important part of the motor control system, and the current sampling accuracy directly affects the motor control effect.

[0003] Normally, a Hall current sensor is used to collect the three-phase current value of the motor, and the collected three-phase current value is output as a voltage signal. After being amplified by a signal amplifier circuit, it is transmitted to a processor chip for calculation and processing.

[0004] At present, when the current signal collected by the Hall current sensor is very small, there will be a problem of insufficient sampling accuracy, and the final calculation result of the processor chip will have a large error with the actual value. Summary of the invention

[0005] An embodiment of the present invention provides a current sampling circuit to improve current sampling accuracy.

[0006] An embodiment of the present invention provides a current sampling circuit, comprising: a first current sampling module, a second current sampling module and a processing module;

[0007] The input end of the first current sampling module and the input end of the second current sampling module both receive the loop voltage signal, and the output end of the first current sampling module and the output end of the second current sampling module are electrically connected to the processing module respectively;

[0008] The first current sampling module is used to amplify the loop voltage signal by m times to obtain a first voltage signal allowed to be received by the processing module and output it to the processing module, where m≥1;

[0009] The second current sampling module is used to amplify the loop voltage signal by mn times to obtain a second voltage signal allowed to be received by the processing module and output it to the processing module, where n>1;

[0010] The processing module is used to calculate a first loop current according to the first voltage signal, and to calculate a second loop current according to the second voltage signal. If the first loop current is in a current sampling interval of the second current sampling module, the second loop current is determined as a target loop current.

[0011] In the embodiment of the present invention, the operational amplification factor of the second circuit sampling module is n times the operational amplification factor of the first current sampling module, which is equivalent to amplifying the loop voltage signal by mn times, so the precision after amplification is more accurate than that of the first current sampling module, and is suitable for sampling small current signals of the target device. The corresponding first current sampling module with a smaller operational amplification factor is suitable for sampling large current signals of the target device. The processing module realizes the sampling of signals amplified by m times through the first current sampling module, and the processing module realizes the sampling of signals amplified by mn times through the second current sampling module. Then, the current sampling circuit realizes the sampling of signals with different amplification factors, and different amplification factors can provide signals with different precisions. The processing module determines the current signal of the target device according to the different sampling intervals to which the calculated current signal belongs, so that the current signal collected by the current sampling circuit is more accurate, the error is reduced, and high-precision current sampling is realized. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the prior art descriptions. Obviously, although the drawings described below are some specific embodiments of the present invention, for those skilled in the art, the basic concepts of the device structure, driving method and manufacturing method disclosed and suggested by the various embodiments of the present invention can be expanded and extended to other structures and drawings, and there is no doubt that these should be within the scope of the claims of the present invention.

[0013] Figure 1 is a schematic diagram of a current sampling circuit provided by an embodiment of the present invention;

[0014] Figure 2 is a structural schematic diagram of a first current sampling module;

[0015] Figure 3 is a structural schematic diagram of a second current sampling module;

[0016] Figure 4 is a circuit diagram of a first current sampling module;

[0017] Figure 5 is a circuit diagram of the second current sampling module. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described through implementation methods with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the basic concepts disclosed and suggested by the embodiments of the present invention, all other embodiments obtained by those skilled in the art are within the scope of protection of the present invention.

[0019] refer to Figure 1 FIG. 1 is a schematic diagram of a current sampling circuit provided by an embodiment of the present invention. The current sampling circuit provided by this embodiment can be applied to any device for current sampling and detection.

[0020] The current sampling circuit provided in this embodiment includes: 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 electrically connected to the processing module 3 respectively; the first current sampling module 1 is used to amplify the loop voltage signal by m times, obtain a first voltage signal that the processing module 3 allows to receive and output it to the processing module 3, m≥1; the second current sampling module 2 is used to amplify the loop voltage signal by mn times, obtain a second voltage signal that the processing module 3 allows to receive and output it to the processing module 3, n>1; the processing module 3 is used to calculate the first loop current according to the first voltage signal, and calculate the second loop current according to the second voltage signal, and if the first loop current is in the current sampling interval of the second current sampling module 2, the second loop current is determined as the target loop current.

[0021] The optional current sampling circuit also includes: a current sensor 4, the output end of the current sensor 4 is electrically connected to the input end of the first current sampling module 1 and the input end of the second current sampling module 2 respectively; the current sensor 4 is used to collect the current signal in the loop and convert the current signal into a loop voltage signal.

[0022] In this embodiment, the current sensor 4 collects the current signal in the loop and converts the current signal into a voltage signal, which is the 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. The optional current sensor 4 is any current sensor such as a Hall sensor, which is not specifically limited in the present invention. The optional current sensor 4 is used to collect current signals in equipment or circuits such as motors. For example, the Hall sensor collects the current signal of the U phase or the W phase of the motor and converts the current signal into a loop voltage signal.

[0023] In this embodiment, the current sampling circuit includes a first current sampling module 1 and a second current sampling module 2, the input end of the first current sampling module 1 and the input end of the second current sampling module 2 receive the same 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 electrically connected to the processing module 3 respectively.

[0024] The first current sampling module 1 amplifies the loop voltage signal m times, while the second current sampling module 2 amplifies the loop voltage signal mn times. The first current sampling module 1 and the second current sampling module 2 have different amplification factors for the same loop voltage signal, and the amplification factor of the second current sampling module 2 is n times that of the first current sampling module 1. For example, if n=4, the amplification factor of the loop voltage signal by the second current sampling module 2 is 4 times that of the first current sampling module 1; that is, the first current sampling module 1 amplifies the loop voltage signal m times, and the second current sampling module 2 is equivalent to amplifying all numerical values ​​of the first current sampling module 1 by 4 times.

[0025] The first current sampling module 1 receives a loop voltage signal, amplifies the loop voltage signal by m times, processes it to obtain a first voltage signal that the processing module 3 allows to receive, and then outputs it to the processing module 3. 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, amplifies the loop voltage signal by mn times, processes it to obtain a second voltage signal that the processing module 3 allows to receive, and then outputs it to the processing module 3. The processing module 3 receives the second voltage signal amplified by mn times.

[0026] The optional processing module 3 is a microcontroller such as an MCU or a single-chip microcomputer. Such microcontrollers have a standard level format, that is, they can only receive signals within their standard level format. For example, if the standard level format of the MCU is 0V to 3.3V, then if the voltage signal generated by the first current sampling module 1 exceeds the standard level format of the processing module 3, only a 3.3V voltage signal can be provided to the processing module 3, and the excess voltage is divided to the ground; on the contrary, if the voltage signal generated by the first current sampling module 1 meets the standard level format of the processing module 3, then the voltage signal generated by the first current sampling module 1 is directly input to the processing module 3. Therefore, the first voltage signal is actually a voltage signal generated by the first current sampling module 1 that meets 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 that meets the standard level format of the processing module 3. The processing module 3 receives a voltage signal that meets its standard level format, which can protect the processing module 3 from high voltage shocks and ensure the performance and service life of the processing module 3.

[0027] It is known that the second current sampling module 2 is equivalent to amplifying all the values ​​of the first current sampling module 1 by n times, 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 must have a first current sampling interval, and the current calculated by the processing module 3 according to the second voltage signal must have a second current sampling interval, and the first current sampling interval is n times the second current sampling interval. For example, if the first current sampling interval is [-30A, +30A], n=4, then the second current sampling interval is [-7.5A, +7.5A].

[0028] The processing module 3 stores the second current sampling interval corresponding to the second current sampling module 2. It can be understood that the sampling interval of the loop voltage signal is different when the object device of current acquisition is different. For example, when the object device of current acquisition is a motor, the loop current signal generated by the motor can be [-30A, +30A], and the sampling interval of the loop voltage signal converted by the current sensor is [-4V, +4V]. This is an example and is not limited to this.

[0029] In addition, on this 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 factor of the second current sampling module is different, and the interval of the second loop current corresponding to the second voltage signal generated by the second current sampling module is also different. Specifically, the 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=4, the current sampling interval of the second current sampling module is [-7.5A, +7.5A]; if n=6, the current sampling interval of the second current sampling module is [-5A, +5A].

[0030] When the current signal collected by the current sensor 4 is 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. Then the voltage signal generated by the first current sampling module 1 and the voltage signal generated by the second current sampling module 2 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 the first loop current according to the first voltage signal, and calculates the second loop current according to the second voltage signal. Obviously, the detected first loop current and the second loop current are both in the current sampling interval corresponding to the second current sampling module 2, which means that the voltage signal output by the second current sampling module 2 is not divided to the ground, so 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, to achieve sampling detection of small currents, and the current sampling result is more accurate. Among them, the target loop current can be understood as the current current signal of the sampled object device.

[0031] The optional processing module 3 is also used to determine the first loop current as the target loop current when it is detected that the first loop current exceeds the current sampling interval of the second current sampling module 2. When the current signal collected by the current sensor 4 exceeds the current sampling interval of the second current sampling module 2, the current signal of the object device at the current moment is characterized as a large current signal. Then the voltage signal generated by the first current sampling module 1 based on this conforms to the standard level format of the processing module 3, and the part of the voltage signal generated by the second current sampling module 2 based on this that exceeds the standard level format is divided to the ground. The processing module 3 receives the first voltage signal and the second voltage signal, wherein the second voltage signal is equal to 3.3V, and the first loop current is calculated according to the first voltage signal, and the second loop current is calculated 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 means 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 to achieve sampling of large current.

[0032] In other embodiments, the processing module may be directly electrically connected to the motor to obtain the rotation speed or load size of the motor.

[0033] The target sampling module can be switched with the motor speed as the reference value. For example, a speed threshold is stored in the processing module. When the motor speed detected by the processing module is less than or equal to the speed threshold, it means that the motor current is small. The second current sampling module with a larger amplification factor can be directly determined as the target sampling module, and the loop current is calculated according to the second voltage signal, and the obtained loop current is determined as the motor current; when the motor speed detected by the processing module is greater than the speed threshold, it means that the motor current is large. The first current sampling module can be directly determined as the target sampling module, and the loop current is calculated according to the first voltage signal, and the obtained loop current is determined as the motor current. The calculation steps are reduced.

[0034] The target sampling module can be switched with the motor load as the 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 means that the motor current is small. The second current sampling module with a larger amplification factor can be directly determined as the target sampling module, and the loop current is calculated according to the second voltage signal, and the obtained loop current is determined as the motor current; when the motor load detected by the processing module is greater than the load threshold, it means that the motor current is large. The first current sampling module can be directly determined as the target sampling module, and the loop current is calculated according to the first voltage signal, and the obtained loop current is determined as the motor current. The calculation steps are reduced.

[0035] In this embodiment, the operational amplification factor of the second circuit sampling module is n times that of the first current sampling module, which is equivalent to amplifying the loop voltage signal by mn times, so the precision after amplification is more accurate than that of the first current sampling module, and is suitable for sampling small current signals of the target device. The corresponding first current sampling module with a smaller operational amplification factor is suitable for sampling large current signals of the target device. The processing module realizes the sampling of signals amplified by m times through the first current sampling module, and the processing module realizes the sampling of signals amplified by mn times through the second current sampling module. Then, the current sampling circuit realizes signal sampling with different amplification factors, and different amplification factors can provide signals with different precisions. The processing module determines the current signal of the target device according to the different sampling intervals to which the calculated current signal belongs. This makes the current signal collected by the current sampling circuit more accurate, reduces the error, and realizes high-precision current sampling.

[0036] Exemplarily, based on the above technical solution, Figure 2The optional first current sampling module shown includes: a first operational amplifier unit 11 and a first clamping unit 12; the input end of the first operational amplifier unit 11 receives the loop voltage signal, the output end of the first operational amplifier unit 11 and the first clamping unit 12 are connected in parallel and then electrically connected to the processing module 3; the loop voltage signal is amplified by the first operational amplifier unit 11 by m times, and then passes through the first clamping unit 12 for clamping protection to generate the first voltage signal that the processing module 3 allows to receive. The optional first current sampling module also includes: a first filtering unit 13; the output end of the first operational amplifier 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 to the first clamping unit 12; the loop voltage signal is amplified by the first operational amplifier unit 11 by m times, and then passes through the first filtering unit 13 and the first clamping unit 12 for clamping protection to generate the first voltage signal that the processing module 3 allows to receive.

[0037] In this embodiment, the first operational amplifier unit 11 is used to operationally amplify the received signal, specifically, after the operational amplification is m times, it is transmitted to the first clamping unit 12. The first clamping unit 12 is used to clamp the received signal for protection. It is known that the processing module 3 has a standard level format, and the first clamping unit 12 is mainly used to clamp the received signal to conform to the standard level format of the processing module 3, so that the excess voltage signal is divided 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 amplifier unit 11 does not exceed 3.3V, the signal can directly enter the processing module 3 through the first clamping unit 12, and when the signal output by the first operational amplifier unit 11 (such as 5V) 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. In this way, the processing module 3 can be protected.

[0038] A first filtering unit 13 is also provided before the first clamping unit 12. The first filtering unit 13 is used to perform low-pass filtering on the signal output by the first operational amplifier unit 11, so that the low-frequency signal can pass normally, while 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.

[0039] like Figure 3The optional second current sampling module shown includes: a second operational amplifier 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 amplifier unit 21 receives the loop voltage signal, the current limiting unit 22 is coupled between the output end of the second operational amplifier unit 21 and the input end of the voltage following unit 23, the output end of the voltage following unit 23 and the second clamping unit 24 are connected in parallel and then electrically connected to the processing module 3; the loop voltage signal is operationally amplified by mn times by the second operational amplifier unit 21, and then passes through the current limiting unit 22 to limit the current, the voltage following unit 23 to shape it, and the second clamping unit 24 to clamp and protect it to generate a second voltage signal that the processing module 3 allows to receive.

[0040] The optional second current sampling module also includes: 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; the loop voltage signal is amplified by the second operational amplifier unit 21 by mn times, and then passes through the current limiting unit 22 to limit the current, the voltage following unit 23 to shape, the second filtering unit 25 to filter, and the second clamping unit 24 to clamp the protection generation processing module 3 to allow the second voltage signal to be received.

[0041] The optional voltage follower unit 23 includes 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 to the current limiting unit 22, and the output end of the operational amplifier is electrically connected to the first end of the second filtering unit 25.

[0042] In this embodiment, the second operational amplifier unit 21 is used to operationally amplify the received signal, specifically, to operationally amplify the signal mn times and then transmit it to the current limiting unit 22. The current limiting unit 22 is used to limit the current of the received signal, so that the voltage amplitude of the received signal remains unchanged, but the current is greatly reduced. The voltage follower unit 23 is used to reprocess the received current, shape the waveform, etc., to improve the stability of the signal, and to achieve low-resistance output, and the output and the subsequent circuit will not affect each other. The second clamping unit 24 is used to clamp the received signal for protection. It is known that the processing module 3 has a standard level format, and the second clamping unit 24 is mainly used to clamp the received signal to conform to the standard level format of the processing module 3, so that the excess voltage signal is divided 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 passing through the second clamping unit 24 (such as 12V) 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. In this way, the processing module 3 can be protected.

[0043] A second filtering unit 25 is further provided after the voltage following unit 23 , and the second filtering unit 25 is used to perform low-pass filtering on the received signal, so that the low-frequency signal can pass normally, while 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 .

[0044] It can be understood that after the processing module calculates the target loop current, the next step of controlling the target device such as a motor can be determined according to the target loop current, and the specific implementation method thereof will not be described in detail herein.

[0045] In an embodiment of the present invention, the current sampling circuit can amplify different multiples, including m times and nm times. When the signal output by the current sensor is very small, the processing module can use the signal of the second current sampling module with a larger amplification factor to perform current calculations; when the signal output by the current sensor is large, the processing module can use the signal of the first current sampling module with a smaller amplification factor to perform current calculations. The current sampling circuit combines fine sampling and coarse sampling, and the processing module dynamically switches according to the current size, so that the amplification factor is always in the optimal working area, which improves the accuracy of the sampling results of current signals of different sizes, reduces the error between the signal received by the current sampling module and the data calculated by the processing module, and realizes high-precision sampling of current signals of different sizes. In addition, the devices used in the current sampling circuit are inexpensive, and can use simple structures and operation logic to achieve high-precision current sampling, reducing production costs.

[0046] On this basis, an embodiment of the present invention provides a current sampling circuit.

[0047] The first current sampling module in the current sampling circuit is as follows Figure 4 As shown, it includes a first operational amplifier unit 11, a first filtering unit 13 and a first clamping unit 12, and the first voltage signal UA outputted by it meets the standard level format of the processing module. The specific circuit structure and device connection method of each unit are as follows Figure 4 As shown, no further details are given here.

[0048] The second current sampling module in the current sampling circuit is as follows: Figure 5 As shown, it includes a second operational amplifier unit 21, a current limiting unit 22, a voltage follower unit 23, a second filter unit 25 and a second clamp unit 24, and the second voltage signal UB outputted by it meets the standard level format of the processing module. The specific circuit structure and device connection method of each unit are as follows Figure 5 As shown, no further details are given here.

[0049] 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.

[0050] The target device of the optional current sampling circuit is a motor, the current sensor is a Hall sensor, the processing module is MUC, and its standard level format is 0-3.3V, then the reference voltage of the current sampling circuit is 1.65V. The upper limit of the actual working current of the motor is +30A and the lower limit is -30A, the upper limit of the voltage output by the Hall sensor is +4V and the lower limit is -4V. Then the interval of the loop voltage signal received by the first current sampling module and the second current sampling module is [-4V, +4V], that is, the upper limit of IU+ is +4V, and the lower limit of IU- is -4V. m can be selected as 3.3 / 8 and n as 4.

[0051] refer to Figure 4 , the first current sampling module amplifies [-4V, +4V] by 3.3 / 8 times, then the voltage upper limit of its output terminal UA is, U-A+=(3.3 / 8)*(+4V)+1.65V=3.3V, the voltage lower limit of UA is, UA-=(3.3 / 8)*(-4V)+1.65V=0V, then after amplification by m times, the first current sampling module converts [-4V, +4V] into [0V, +3.3V] and then outputs it. Among them, the output end of the first operational amplifier unit 11 is 0-3.3V, and then filtered by the first filtering unit 13, and clamped by the first clamping unit 12, then the voltage range of the output terminal UA 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 resistance ratio of R146 and R144.

[0052] refer to Figure 5, the second current sampling module amplifies [-4V, +4V] by 3.3 / 2 times, and the voltage upper limit of its output terminal UB should be 3.3V, and the voltage lower limit of UB should be 0V. It is known that the reference voltage is 1.65V, then U-B+=(3.3 / 2)*(+1V)+1.65V=3.3V, UB-=(3.3 / 2)*(-1V)+1.65V=0V, then after amplifying mn times, the second current sampling module is equivalent to intercepting [-1V, +1V] in [-4V, +4V] and amplifying it by 3.3 / 2 times, and then converting it into [0V, +3.3V] output. Among them, the output end of the second operational amplifier unit 21 is 0-13.2V, and then the current energy is greatly weakened by the current limiting resistor R160 without changing the voltage. The clamping diode in the voltage follower unit 23 clamps [0, 13.2V] to [0V, +3.3V] and then outputs after the secondary operational amplifier operation, and is filtered by the second filtering unit 25 and clamped by the second clamping unit 24 in turn. Then, the voltage range of the output end UB is limited to [0V, +3.3V], and the sampled current range is -7.5A to +7.5A. It can be understood that the amplification factor of the second operational amplifier unit 21 is mainly determined by the resistance ratio of R156 and R154.

[0053] The optional current limiting unit 22 is a current limiting resistor R160, and the resistance of the current limiting resistor is 1KΩ to 10KΩ, which can greatly weaken the current and ensure that the voltage remains unchanged. The optional clamping unit includes a clamping diode, and the clamping diode selects a 3.3V voltage regulator. Once a voltage exceeding 3.3V flows through, it will be reversely conducted to the ground, thereby protecting the processing module from impact and damage.

[0054] It can be understood that the current sampling circuit provided above is only an example, in which the selection of device parameters can be adjusted according to different target devices or different loop voltage signals, but is not limited to this.

[0055] 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 second current sampling module has better precision in amplifying small currents than the first current sampling module, and correspondingly has higher precision in detecting small currents.

[0056] It is known that the rated current range of the motor is -30A to +30A, and the current is 0A when the motor stops working. When the motor is lightly loaded or at a low speed, the current will fluctuate in a small range around 0A. In the large amplitude range of 7.5A to 30A and -7.5A to -30A, the voltage signal output by the first current sampling module is used for current calculation, which can reduce the large current sampling error and improve the sampling accuracy. In the small amplitude range of -7.5A to +7.5A, a second current sampling module with a higher amplification factor is used to amplify all the values ​​of the first current sampling module by n times. The processing module performs current calculations based on the voltage signal it outputs, which can reduce the small current sampling detection error and improve the sampling detection accuracy.

[0057] Note that the above are only preferred embodiments of the present invention and the technical principles used. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments, combinations and substitutions can be made by those skilled in the art without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in more detail through the above embodiments, the present invention is not limited to the above embodiments, and may include more other equivalent embodiments without departing from the concept of the present invention, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. A current sampling circuit, characterized in that: include: 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 the loop voltage signal, and the output end of the first current sampling module and the output end of the second current sampling module are electrically connected to the processing module respectively; The first current sampling module is used to amplify the loop voltage signal by m times to obtain a first voltage signal allowed to be received by the processing module and output it to the processing module, where m≥1; The second current sampling module is used to amplify the loop voltage signal by mn times to obtain a second voltage signal allowed to be received by the processing module and output it to the processing module, where n>1; The processing module is used to calculate a first loop current according to the first voltage signal, and to calculate a second loop current according to the second voltage signal. If the first loop current is in a current sampling interval of the second current sampling module, the second loop current is determined as a target loop current.

2. The current sampling circuit according to claim 1, characterized in that: The processing module is further configured to determine the first loop current as a target loop current when it is detected that the first loop current exceeds a current sampling interval of the second current sampling module.

3. The current sampling circuit according to claim 1, characterized in that: The first current sampling module includes: a first operational amplifier unit and a first clamping unit; The input end of the first operational amplifier unit receives the loop voltage signal, and the output end of the first operational amplifier unit and the first clamping unit are connected in parallel and then electrically connected to the processing module; The loop voltage signal is amplified m times by the first operational amplifier unit and then clamped and protected by the first clamp unit to generate a first voltage signal that the processing module is allowed to receive.

4. The current sampling circuit according to claim 3, characterized in that: The first current sampling module further includes: a first filtering unit; The output end of the first operational amplifier unit is electrically connected to the first end of the first filtering unit, and the second end of the first filtering unit is connected in parallel with the first clamping unit; The loop voltage signal is amplified m times by the first operational amplifier unit, and then filtered by the first filter unit and clamped by the first clamp unit in sequence to generate a first voltage signal that the processing module is allowed to receive.

5. The current sampling circuit according to claim 1, characterized in that: The second current sampling module includes: a second operational amplifier unit, a current limiting unit, a voltage following unit and a second clamping unit; The input end of the second operational amplifier unit receives the loop voltage signal, the current limiting unit is coupled between the output end of the second operational amplifier unit and the input end of the voltage follower unit, and the output end of the voltage follower unit and the second clamping unit are connected in parallel and then electrically connected to the processing module; The loop voltage signal is amplified mn times by the second operational amplifier unit, and then passes through the current limiting unit to limit the current, the voltage following unit to shape it, and the second clamping unit to clamp and protect it to generate a second voltage signal that the processing module allows to receive.

6. The current sampling circuit according to claim 5, characterized in that: The second current sampling module further includes: a second filtering unit; The output end of the voltage follower 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; The loop voltage signal is amplified mn times by the second operational amplifier unit, and then passes through the current limiting unit to limit the current, the voltage following unit to shape, the second filtering unit to filter, and the second clamping unit to clamp and protect to generate the second voltage signal that the processing module allows to receive.

7. The current sampling circuit according to claim 6, characterized in that: The voltage follower unit includes 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 to the current limiting unit, and the output end of the operational amplifier is electrically connected to the first end of the second filtering unit.

8. The current sampling circuit according to claim 5, characterized in that: The current limiting unit is a current limiting resistor, and the resistance of the current limiting resistor is 1KΩ to 10KΩ.

9. The current sampling circuit according to claim 1, characterized in that: Also includes: A current sensor, wherein an output end of the current sensor is electrically connected to an input end of the first current sampling module and an input end of the second current sampling module respectively; The current sensor is used to collect the current signal in the loop and convert the current signal into the loop voltage signal.

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