Current sampling circuit of shunt
By designing the shunt current sampling circuit, using the shunt and resistors with equal resistance values to average the sampling signal, the problem of PCB distribution impedance affecting the current sampling accuracy in large current scenarios is solved, accurate current sampling and exquisite design are achieved, and cost is reduced.
Patent Information
- Application Number
- CN202421499639.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-06-27
- Publication Date
- 2025-03-07
- Estimated Expiration
- 2034-06-27
AI Technical Summary
In the case of large current shunt current sampling circuit, the current sampling accuracy is reduced and the sampling output is too large.
A shunt current sampling circuit is designed, including N shunts with equal resistance values, N first resistors and N second resistors, and averages the sampled signals through a resistor network to eliminate the influence of the PCB distributed impedance.
Accurate current sampling is achieved, and the sampling value is consistent with the theoretical calculated value, which improves the accuracy of current sampling, and has a wide range of application value due to the simple design and low cost.
Smart Images
Figure CN222580174U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the field of current sampling, and more specifically to a shunt current sampling circuit. Background Art
[0002] The shunt current sampling circuit is widely used due to its simple circuit and low cost. When used in high current scenarios, the resistance of the shunt is small due to the power consumption limit, and multiple parallel connections are required. The schematic diagram is as follows Figure 1 As shown. Figure 1 As shown, shunts R1, R2, and R3 are connected in parallel, and the current sampling module 100 is connected at both ends of the shunts R1, R2, and R3. However, when this shunt current sampling circuit is actually laid out on a PCB, the copper sheet width is wide under high current conditions and the shunt resistance is small. The PCB copper sheet impedance cannot be ignored, which will cause uneven current between shunts and affect the accuracy of current sampling. Therefore, its equivalent circuit is as follows: Figure 2 shown.
[0003] like Figure 2 As shown, the PCB equivalent impedance from the device pad to the shunts R1, R2, and R3 is Rs1, Rs2, and Rs3, and the total current is I. I1, I2, and I3 are the currents flowing through the shunts R1, R2, and R3, respectively. Figure 2 It can be seen that the distance between the shunt R2 and the pad is the shortest, so the corresponding PCB equivalent impedance Rs2 is smaller than the PCB equivalent impedance Rs1 and Rs3 of the shunts R1 and R3. If R1, R2, and R3 are all equal to R, then the total equivalent impedance of the shunts R1, R2, and R3 is R+Rs1, R+Rs2, and R+Rs3, respectively. Since Rs2 is smaller than Rs1 and Rs3, the current I2 flowing through the shunt R2 is greater than the current I1 and I3 flowing through the shunts R1 and R3. a and b are the sampling points for current sampling, which are sent to the current sampling module 100 for processing after sampling, and the theoretical sampling value is I*R / 3. However, since I2 is greater than the average current of the three shunts, the sampling output of this current sampling circuit will be larger than the theoretical calculation. Utility Model Content
[0004] The technical problem to be solved by the utility model is to provide a shunt current sampling circuit which can eliminate the influence of PCB distributed impedance on current sampling accuracy and realize accurate current sampling in view of the above-mentioned defects of the prior art.
[0005] The technical solution adopted by the utility model to solve the technical problem is: constructing a shunt current sampling circuit, including N shunts, N first resistors, N second resistors, and a current sampling module;
[0006] The first end of each shunt is connected to the first end of the device to be detected, and the second end of each shunt is connected to the second end of the device to be detected; the third end of each shunt is connected to the first end of the current sampling module via one of the first resistors, and the fourth end of each shunt is connected to the second end of the current sampling module via one of the second resistors;
[0007] Wherein N is an integer greater than or equal to 2.
[0008] In the shunt current sampling circuit described in the present invention, the N shunts are resistors with equal resistance values.
[0009] In the shunt current sampling circuit described in the present invention, the N first resistors are resistors with equal resistance values.
[0010] In the shunt current sampling circuit described in the present invention, the N second resistors are resistors with equal resistance values.
[0011] In the shunt current sampling circuit described in the present invention, the N first resistors and the N second resistors are resistors with equal resistance values.
[0012] In the shunt current sampling circuit described in the utility model, the third ends of each shunt are directly opposite to each other, and the fourth ends of each shunt are directly opposite to each other.
[0013] In the shunt current sampling circuit described in the utility model, the current sampling module includes an operational amplifier and a DSP, the non-phase input end of the operational amplifier is the second end of the current sampling module, the inverting input end is the first end of the current sampling module, and the output end is connected to the DSP.
[0014] Another technical solution adopted by the utility model to solve the technical problem is: constructing a shunt current sampling circuit, which is composed of N shunts, N first resistors, N second resistors, and a current sampling module;
[0015] The first end of each shunt is connected to the first end of the device to be detected, and the second end of each shunt is connected to the second end of the device to be detected; the third end of each shunt is connected to the first end of the current sampling module via one of the first resistors, and the fourth end of each shunt is connected to the second end of the current sampling module via one of the second resistors;
[0016] Wherein N is an integer greater than or equal to 2;
[0017] The N shunts are resistors with equal resistance values; the N first resistors and the N second resistors are resistors with equal resistance values; the third ends of each shunt are opposite to each other, and the fourth ends of each shunt are opposite to each other.
[0018] In the shunt current sampling circuit described in the utility model, the current sampling module includes an operational amplifier and a DSP, the non-phase input end of the operational amplifier is the second end of the current sampling module, the inverting input end is the first end of the current sampling module, and the output end is connected to the DSP.
[0019] The shunt current sampling circuit of the utility model can obtain an accurate current sampling value after averaging the sampling signals of each parallel shunt through a resistor network, which is consistent with the theoretical calculated value, thereby improving the accuracy of current sampling. Moreover, due to its sophisticated design, simple structure and excellent performance, it is low-cost, easy to implement and has a wide range of application value. BRIEF DESCRIPTION OF THE DRAWINGS
[0020] The present invention will be further described below with reference to the accompanying drawings and embodiments, in which:
[0021] Figure 1 is a schematic diagram of a shunt current sampling circuit of the prior art;
[0022] Figure 2 yes Figure 1 The equivalent circuit diagram of the shunt current sampling circuit shown;
[0023] Figure 3 It is a schematic diagram of a preferred embodiment of the shunt current sampling circuit of the utility model;
[0024] Figure 4 yes Figure 3 The equivalent circuit diagram of the shunt current sampling circuit shown;
[0025] Figure 5 It is a schematic diagram of another preferred embodiment of the shunt current sampling circuit of the utility model;
[0026] Figure 6 It is a schematic diagram of another preferred embodiment of the shunt current sampling circuit of the utility model;
[0027] Figure 7 It is a schematic diagram of a preferred embodiment of a current sampling module of a shunt current sampling circuit of the utility model. DETAILED DESCRIPTION
[0028] In order to make the purpose, technical solution and advantages of the utility model more clear, the utility model is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the utility model and are not used to limit the utility model.
[0029] Figure 3 Schematic diagram of a preferred embodiment of the shunt current sampling circuit of the utility model. Figure 3 As shown, the shunt current sampling circuit of the present invention includes three shunts R1, R2, and R3, three first resistors R11, R12, and R13, three second resistors R21, R22, and R23, and a current sampling module 100. Figure 3 As shown, the first end of the shunt R1 is connected to the first end of the device to be detected, the second end is connected to the second end of the device to be detected, the third end A1 is connected to the first end of the current sampling module 100 via the first resistor R11, and the fourth end B1 is connected to the second end of the current sampling module via the second resistor R21. The first end of the shunt R2 is connected to the first end of the device to be detected, the second end is connected to the second end of the device to be detected, the third end A2 is connected to the first end of the current sampling module 200 via the first resistor R12, and the fourth end B2 is connected to the second end of the current sampling module via the second resistor R22. The first end of the shunt R3 is connected to the first end of the device to be detected, the second end is connected to the second end of the device to be detected, the third end A3 is connected to the first end of the current sampling module 300 via the first resistor R13, and the fourth end B3 is connected to the second end of the current sampling module via the second resistor R23.
[0030] Preferably, the resistance values of the shunts R1, R2, and R3 are equal, the resistance values of the first resistors R11, R12, and R13 are equal, and the resistance values of the second resistors R21, R22, and R23 are equal. More preferably, the resistance values of the shunts R1, R2, and R3 are equal, all R, and the resistance values of the first resistors R11, R12, and R13 and the second resistors R21, R22, and R23 are equal, all r.
[0031] Preferably, the third end A1 and the fourth end B1 of the shunt R1, the third end A2 and the fourth end B2 of the shunt R2, and the third end A3 and the fourth end B3 of the shunt R3 are all located at or near the middle position of the shunt. More preferably, the third end A1 of the shunt R1, the third end A2 of the shunt R2, and the third end A3 of the shunt R3 are at the same position on the shunt, that is, the third end A1 of the shunt R1, the third end A2 of the shunt R2, and the third end A3 of the shunt R3 are directly opposite to each other, so that the resistances on the corresponding branches are the same. The fourth end B1 of the shunt R1, the fourth end B2 of the shunt R2 and the fourth end B3 of the shunt R3 are also at the same position on the shunt, that is, the fourth end B1 of the shunt R1, the fourth end B2 of the shunt R2 and the fourth end B3 of the shunt R3 are directly opposite to each other, so that the resistance on each corresponding branch is the same.
[0032] Of course, in other preferred embodiments of the present invention, the third end A1 of the diverter R1, the third end A2 of the diverter R2, and the third end A3 of the diverter R3 may be slightly offset instead of facing each other, and the fourth end B1 of the diverter R1, the fourth end B2 of the diverter R2, and the fourth end B3 of the diverter R3 may also be slightly offset instead of facing each other. These all fall within the protection scope of the present invention.
[0033] Here, the current sampling module 100 may adopt any isolated or non-isolated current sampling circuit known in the art, such as an operational amplifier circuit or an optical coupler circuit, which all fall within the protection scope of the present utility model.
[0034] Figure 4 yes Figure 3 The equivalent circuit diagram of the shunt current sampling circuit is shown below. Figure 4The principle of the shunt current sampling circuit of the utility model is described as follows. As mentioned above, the resistance of the shunts R1, R2, and R3 is R. Two sampling signal lines are drawn out in the middle of each shunt R1, R2, and R3, respectively, for a total of 6 signal lines. Each sampling signal + and - is connected in series with a first resistor R11, R12, and R13 with a resistance of r and the second resistor R21, R22, and R23 before being sent to the current sampling module. Since the resistor r is much smaller than the input impedance of the current sampling module 100, V1, V2, and V3 are the voltages on each sampling side. Based on the circuit calculation analysis, the total output signal Vs = (V1 + V2 + V3) / 3 = (I1 * R1 + I2 * R2 + I3 * R3) / 3 = I * R / 3 can be obtained; the theoretical calculation formula is Vs = I * R / 3, and the sampling value obtained by the circuit is exactly the same as the value of the theoretical calculation formula. This circuit can eliminate the influence of the PCB distributed impedance on the current sampling accuracy and achieve accurate current sampling.
[0035] The shunt current sampling circuit of the utility model can obtain an accurate current sampling value after averaging the sampling signals of each parallel shunt through a resistor network, which is consistent with the theoretical calculated value, thereby improving the accuracy of current sampling. Moreover, due to its sophisticated design, simple structure and excellent performance, it is low-cost, easy to implement and has a wide range of application value.
[0036] Figure 5 It is a schematic diagram of another preferred embodiment of the shunt current sampling circuit of the utility model. Figure 5 The preferred embodiment shown is Figure 3 The preferred embodiment shown is similar, except that the resistance values of the shunts R1, R2, and R3 are equal, the resistance values of the first resistors R11, R12, and R13 are equal, and the resistance values of the second resistors R21, R22, and R23 are equal, but the resistance values of the first resistors R11, R12, and R13 are not equal to the resistance values of the second resistors R21, R22, and R23. Figure 5 As shown, the resistance values of the first resistors R11, R12, and R13 are equal, which is r1, and the resistance values of the second resistors R21, R22, and R23 are equal, which is r2. Figure 5 The principle of the embodiment shown is Figure 3 The embodiments shown are similar and will not be described again here.
[0037] Figure 6 FIG. 1 is a schematic diagram of another preferred embodiment of the shunt current sampling circuit of the utility model. Figure 6As shown, the shunt current sampling circuit of the present invention includes N shunts R1, R2...RN, N first resistors, N second resistors, and a current sampling module 100. The first end of each of the shunts R1, R2...RN is respectively connected to the first end of the device to be detected, and the second end of each of the shunts R1, R2...RN is respectively connected to the second end of the device to be detected; the third end of each of the shunts R1, R2...RN is respectively connected to the first end of the current sampling module 100 via a first resistor, and the fourth end of each of the shunts R1, R2...RN is respectively connected to the second end of the current sampling module 100 via a second resistor. In the present utility model, as long as N is an integer greater than or equal to 2. That is, it is applicable when the number of shunts in parallel N is greater than or equal to 2, and N resistors are respectively connected in series at both ends of the current sampling module 100. Preferably, the N shunts R1, R2...RN are shunts with equal resistance values. The N first resistors and the N second resistors are resistors with equal resistance values, the third ends of each of the shunts R1, R2...RN are opposite to each other, and the fourth ends R1, R2...RN of each of the shunts are opposite to each other.
[0038] Of course, as mentioned above, the third ends of each of the shunts R1, R2 ... RN may also be slightly staggered from each other, and the fourth ends R1, R2 ... RN of each of the shunts may also be slightly staggered from each other. The N first resistors and the N second resistors are resistors with equal resistance values, but the resistance values of the first resistors and the second resistors are not equal, which all fall within the protection scope of the present utility model.
[0039] Figure 7 Schematic diagram of a preferred embodiment of the current sampling module of the shunt current sampling circuit of the utility model. Figure 7 As shown, the current sampling module 100 includes an operational amplifier and a DSP, wherein the non-inverting input terminal of the operational amplifier is the second terminal of the current sampling module, the inverting input terminal is the first terminal of the current sampling module, and the output terminal is connected to the DSP. The DSP can perform any known processing such as filtering and amplification on the current sampling signal.
[0040] Of course, in other preferred embodiments of the present invention, the current sampling module 100 may also adopt other configurations, which all fall within the protection scope of the present invention.
[0041] It should be noted that the shunt current sampling circuit of the utility model may only include Figure 3-7 The components shown in the figure may also include more components, which all fall within the protection scope of the present utility model.
[0042] Although the present invention is described through specific embodiments, it should be understood by those skilled in the art that various changes and equivalent substitutions may be made to the present invention without departing from the scope of the present invention. In addition, various modifications may be made to the present invention for specific situations or materials without departing from the scope of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed, but should include all implementation methods that fall within the scope of the claims of the present invention.
[0043] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.
Claims
1. A shunt current sampling circuit, characterized in that: It includes N shunts, N first resistors, N second resistors, and a current sampling module; The first end of each shunt is connected to the first end of the device to be detected, and the second end of each shunt is connected to the second end of the device to be detected; the third end of each shunt is connected to the first end of the current sampling module via one of the first resistors, and the fourth end of each shunt is connected to the second end of the current sampling module via one of the second resistors; Wherein N is an integer greater than or equal to 2.
2. The shunt current sampling circuit according to claim 1, characterized in that: The N shunts are resistors with equal resistance values.
3. The shunt current sampling circuit according to claim 2, characterized in that: The N first resistors are resistors with equal resistance values.
4. The shunt current sampling circuit according to claim 3, characterized in that: The N second resistors are resistors with equal resistance values.
5. The shunt current sampling circuit according to claim 2, characterized in that: The N first resistors and the N second resistors are resistors with equal resistance values.
6. The shunt current sampling circuit according to claim 5, characterized in that: The third ends of each of the diverters are opposite to each other, and the fourth ends of each of the diverters are opposite to each other.
7. The shunt current sampling circuit according to claim 6, characterized in that: The current sampling module comprises an operational amplifier and a DSP, wherein the non-phase input terminal of the operational amplifier is the second terminal of the current sampling module, the inverting input terminal is the first terminal of the current sampling module, and the output terminal is connected to the DSP.
8. A shunt current sampling circuit, characterized in that: It is composed of N shunts, N first resistors, N second resistors, and a current sampling module; The first end of each shunt is connected to the first end of the device to be detected, and the second end of each shunt is connected to the second end of the device to be detected; the third end of each shunt is connected to the first end of the current sampling module via one of the first resistors, and the fourth end of each shunt is connected to the second end of the current sampling module via one of the second resistors; Wherein N is an integer greater than or equal to 2; The N shunts are resistors with equal resistance values; the N first resistors and the N second resistors are resistors with equal resistance values; the third ends of each shunt are opposite to each other, and the fourth ends of each shunt are opposite to each other.
9. The shunt current sampling circuit according to claim 8, characterized in that: The current sampling module comprises an operational amplifier and a DSP, wherein the non-phase input terminal of the operational amplifier is the second terminal of the current sampling module, the inverting input terminal is the first terminal of the current sampling module, and the output terminal is connected to the DSP.