CN113866479A - Isolation current detection circuit and method - Google Patents
Isolation current detection circuit and method Download PDFInfo
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- CN113866479A CN113866479A CN202111118159.XA CN202111118159A CN113866479A CN 113866479 A CN113866479 A CN 113866479A CN 202111118159 A CN202111118159 A CN 202111118159A CN 113866479 A CN113866479 A CN 113866479A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
- G01R19/0092—Arrangements for measuring currents or voltages or for indicating presence or sign thereof measuring current only
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R15/00—Details of measuring arrangements of the types provided for in groups G01R17/00 - G01R29/00, G01R33/00 - G01R33/26 or G01R35/00
- G01R15/14—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks
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Abstract
The invention provides an isolation current detection circuit and a method, wherein the circuit comprises: the circuit comprises a current divider, a differential amplification circuit, a linear optical coupler and a conversion circuit; the current divider is connected with the differential amplification circuit and used for collecting current signals; the input of the differential amplification circuit is the potential difference at two ends of the shunt, the differential amplification circuit amplifies the potential difference, and the output voltage of the differential amplification circuit is used for driving the linear optocoupler; the linear optocoupler is connected with the conversion circuit, and the conversion circuit is used for converting the output current of the linear optocoupler into voltage. According to the method, the isolation sampling of the alternating current and direct current signals is completed by adopting low-cost devices, and the cost of isolating current detection is greatly reduced.
Description
Technical Field
The invention belongs to the field of charging piles, and particularly relates to an isolation current detection circuit and method.
Background
The Hall current sensor has the advantages of high precision, high speed and the like, and is widely applied to an isolation sampling circuit of alternating current and direct current at present. However, the price of the hall current sensor is generally higher, and the cost advantage of the product is seriously restricted. Although the current transformer is low in cost and does not need extra power supply, the current transformer can only be used for collecting alternating current, particularly high-frequency alternating current, and cannot be applied to direct current or low-frequency alternating current sampling. With the increasing cost pressure, a low-cost isolated current detection mode is necessary in places where the current sampling precision requirement is not particularly high but the safety performance has special requirements.
Disclosure of Invention
The embodiment of the application provides an isolation current detection circuit and method, which adopt low-cost devices to finish isolation sampling of alternating current and direct current signals, thereby greatly reducing the cost of isolation current detection.
In a first aspect, an embodiment of the present application provides an isolation current detection circuit, including:
the circuit comprises a current divider, a differential amplification circuit, a linear optical coupler and a conversion circuit;
the current divider is connected with the differential amplification circuit and used for collecting current signals; the input of the differential amplification circuit is the potential difference between two ends of the current divider, the differential amplification circuit amplifies the potential difference, and the output voltage of the differential amplification circuit is used for driving a linear optocoupler; the linear optocoupler is connected with the conversion circuit, and the conversion circuit is used for converting the output current of the linear optocoupler into voltage.
Wherein, still include: and the direct current voltage bias module is used for superposing direct current voltage bias on the input end of the differential amplification circuit.
Wherein, the shunt is used for collecting the current in the power circuit.
Wherein the differential amplification circuit includes: one end of a resistor R2 is connected with one end of the shunt, the other end of a resistor R2 is connected with one end of a capacitor C1, one end of a resistor R1 and the non-inverting input end of the first operational amplifier, and the other end of a capacitor C1 is connected with the other end of a resistor R1; one end of a resistor R3 is connected with the other end of the shunt, the other end of a resistor R3 is connected with the reverse input end of the first operational amplifier, one end of a resistor R4 and one end of a capacitor C3, and the other end of a resistor R4 is connected with the other end of a capacitor C3, the output end of the first operational amplifier and one end of a resistor R5; the other end of the resistor R5 is connected with the reverse input end of the second operational amplifier and the 3 pins of the linear optocoupler, the non-inverting input end of the second operational amplifier is grounded, the output end of the second operational amplifier is connected with one end of the resistor R6, and the other end of the resistor R6 is connected with the 1 pin of the linear optocoupler.
The direct-current voltage bias module is connected with the other end of the capacitor C1 and the other end of the resistor R1.
The model of the linear optocoupler is HCNR 201-500E.
Wherein the conversion circuit comprises: the non-inverting input end of the third operational amplifier and the 5 pins of the linear optocoupler are connected with the ground, the inverting input end of the third operational amplifier is connected with the 6 pins of the linear optocoupler and one end of a resistor R7, the other end of a resistor R7 is connected with the output end of the third operational amplifier and one end of a resistor R8, the other end of the resistor R8 is connected with one end of a capacitor C2, and the other end of the capacitor C2 is grounded.
In a second aspect, the present application provides an isolation current detection method using any one of the above isolation current detection circuits, including:
the current divider collects current signals;
the potential difference between two ends of the current divider is used as the input of a differential amplification circuit, the differential amplification circuit amplifies the potential difference, and the output voltage of the differential amplification circuit is used for driving a linear optocoupler;
and the conversion circuit converts the output current of the linear optocoupler into voltage.
Wherein, still include: and superposing direct-current voltage bias on the input end of the differential amplification circuit.
Wherein, the shunt is used for collecting the current in the power circuit.
The isolation current detection circuit and the method have the following beneficial effects:
the isolation current detection circuit of the application comprises: the circuit comprises a current divider, a differential amplification circuit, a linear optical coupler and a conversion circuit; the current divider is connected with the differential amplification circuit and used for collecting current signals; the input of the differential amplification circuit is the potential difference at two ends of the shunt, the differential amplification circuit amplifies the potential difference, and the output voltage of the differential amplification circuit is used for driving the linear optocoupler; the linear optocoupler is connected with the conversion circuit, and the conversion circuit is used for converting the output current of the linear optocoupler into voltage. According to the method, the isolation sampling of the alternating current and direct current signals is completed by adopting low-cost devices, and the cost of isolating current detection is greatly reduced.
Drawings
Fig. 1 is a schematic structural diagram of an isolation current detection circuit according to an embodiment of the present application;
fig. 2 is a schematic diagram of another structure of the isolation current detection circuit according to the embodiment of the present application.
Detailed Description
The present application is further described with reference to the following figures and examples.
In the following description, the terms "first" and "second" are used for descriptive purposes only and are not intended to indicate or imply relative importance. The following description provides embodiments of the invention, which may be combined or substituted for various embodiments, and this application is therefore intended to cover all possible combinations of the same and/or different embodiments described. Thus, if one embodiment includes feature A, B, C and another embodiment includes feature B, D, then this application should also be considered to include an embodiment that includes one or more of all other possible combinations of A, B, C, D, even though this embodiment may not be explicitly recited in text below.
The following description provides examples, and does not limit the scope, applicability, or examples set forth in the claims. Changes may be made in the function and arrangement of elements described without departing from the scope of the disclosure. Various examples may omit, substitute, or add various procedures or components as appropriate. For example, the described methods may be performed in an order different than the order described, and various steps may be added, omitted, or combined. Furthermore, features described with respect to some examples may be combined into other examples.
The invention combines the current divider and the linear optocoupler, collects current signals by using the current divider, and then realizes isolated transmission through the linear optocoupler after proper treatment. The idea is as follows: the current in the power circuit is directly collected by the current divider, then the output potential difference at two ends of the current divider is used as the input of the differential operational amplifier, and the voltage signal which is superposed with a proper direct current voltage bias is converted into a voltage signal for driving the linear optical coupler after proper amplification, so that the isolated transmission of the non-isolated signal sampled by the current divider is realized.
The alloy resistance price of the manganese-copper material is very cheap, the price of the linear optical coupler is not expensive, and even if devices such as an operational amplifier and an isolation power supply are added, the cost of the whole scheme is obviously lower than that of a Hall current sensor, so that the scheme of adopting a current divider and the linear optical coupler can realize the isolation sampling of current with lower cost. In addition, if other circuit parts except the current divider are packaged into modules, only different current dividers are needed to be replaced according to different current grades, and other circuit parameters and calculation methods are unchanged.
As shown in fig. 1, the isolation current detection circuit of the present application includes: a current divider 201, a differential amplification circuit 202, a linear optical coupler 203 and a conversion circuit 204; the current divider 201 is connected with the differential amplification circuit 202 and used for collecting current signals; the input of the differential amplification circuit 202 is the potential difference between two ends of the shunt 201, the differential amplification circuit 202 amplifies the potential difference, and the output voltage of the differential amplification circuit 202 is used for driving the linear optocoupler 203; the linear optical coupler 203 is connected with a conversion circuit 204, and the conversion circuit 204 is used for converting the output current of the linear optical coupler 203 into voltage.
The isolation current detection circuit of the present application further comprises: and the direct current voltage bias module is used for superposing direct current voltage bias on the input end of the differential amplification circuit. The current divider is used for collecting current in the power circuit.
As shown in fig. 2, in the isolated current detection circuit of the present application, the differential amplifier circuit includes: one end of the resistor R2 is connected with one end of the shunt, the other end of the resistor R2 is connected with one end of the capacitor C1, one end of the resistor R1 and the non-inverting input end of the first operational amplifier, and the other end of the capacitor C1 is connected with the other end of the resistor R1; one end of a resistor R3 is connected with the other end of the shunt, the other end of a resistor R3 is connected with the reverse input end of the first operational amplifier, one end of a resistor R4 and one end of a capacitor C3, and the other end of a resistor R4 is connected with the other end of a capacitor C3, the output end of the first operational amplifier and one end of a resistor R5; the other end of the resistor R5 is connected with the reverse input end of the second operational amplifier and the 3 feet of the linear optocoupler, the non-inverting input end of the second operational amplifier is grounded, the output end of the second operational amplifier is connected with one end of the resistor R6, and the other end of the resistor R6 is connected with the 1 foot of the linear optocoupler.
As shown in fig. 2, the dc voltage bias module is connected to the other end of the capacitor C1 and the other end of the resistor R1. The model of the linear optocoupler is HCNR 201-500E. HCNR201-500E is a high linearity analog photocoupler.
As shown in fig. 2, the conversion circuit includes: the non-inverting input end of the third operational amplifier and the 5 pins of the linear optocoupler are connected with the ground, the inverting input end of the third operational amplifier is connected with the 6 pins of the linear optocoupler and one end of a resistor R7, the other end of a resistor R7 is connected with the output end of the third operational amplifier and one end of a resistor R8, the other end of the resistor R8 is connected with one end of a capacitor C2, and the other end of the capacitor C2 is grounded.
As shown in fig. 2, firstly, a suitable shunt Rinsense is selected, and both ends of the Rinsense are introduced into the differential amplifying circuit; selecting a proper amplification factor and connecting the operational amplifier output to a linear optocoupler; the output of the linear optocoupler converts a current signal into a voltage signal through the operational amplifier and then inputs the voltage signal into the ADC module. Assuming that the current measured current is Io, the voltage signal output by the differential operational amplifier is Io × rintense. R1 is R4, R2 is R3, R4/R3 is K, meanwhile, in order to collect negative current and the operational amplifier adopts single power supply for power supply, a direct current voltage bias Vref is superposed on the input end of the differential operational amplifier, the primary side input current IPD1 of the optical coupler is Io Rinsense K/R5, the secondary current IPD2 is VOUT/R7, and the IPD1 is IPD2, so that the optical coupler has the advantages of high efficiency, high reliability and low cost
If R5 ═ R7, then VOUT ═ Io ═ rintense ×, i.e., Io ═ VOUT/(rintense ×) K.
If other parameters except the Rinsense in the circuit are fixed, only the corresponding parameters of the Rinsense need to be adjusted according to different current sampling requirements. Like this can be convenient for modular design, only need adjust Rinsense to different demands, so other circuits can be packaged into independent module, and need not select different models like Hall current sensor, can reduce the kind of material like this, reduce the cost that the material was maintained.
The isolation current detection circuit adopts low-cost devices to complete isolation sampling of alternating current and direct current signals, and greatly reduces the cost of isolation current detection.
The present application further provides an isolation current detection method using any one of the above isolation current detection circuits, including:
the current divider collects current signals;
the potential difference between two ends of the current divider is used as the input of a differential amplification circuit, the differential amplification circuit amplifies the potential difference, and the output voltage of the differential amplification circuit is used for driving a linear optocoupler;
the conversion circuit converts the output current of the linear optocoupler into voltage.
Wherein, still include: and superposing direct-current voltage bias on the input end of the differential amplification circuit.
The shunt is used for collecting current in the power circuit.
Wherein the differential amplification circuit includes: one end of a resistor R2 is connected with one end of the shunt, the other end of a resistor R2 is connected with one end of a capacitor C1, one end of a resistor R1 and the non-inverting input end of the first operational amplifier, and the other end of a capacitor C1 is connected with the other end of a resistor R1; one end of a resistor R3 is connected with the other end of the shunt, the other end of a resistor R3 is connected with the reverse input end of the first operational amplifier, one end of a resistor R4 and one end of a capacitor C3, and the other end of a resistor R4 is connected with the other end of a capacitor C3, the output end of the first operational amplifier and one end of a resistor R5; the other end of the resistor R5 is connected with the reverse input end of the second operational amplifier and the 3 pins of the linear optocoupler, the non-inverting input end of the second operational amplifier is grounded, the output end of the second operational amplifier is connected with one end of the resistor R6, and the other end of the resistor R6 is connected with the 1 pin of the linear optocoupler.
The direct-current voltage bias module is connected with the other end of the capacitor C1 and the other end of the resistor R1.
The model of the linear optocoupler is HCNR 201-500E.
Wherein the conversion circuit comprises: the non-inverting input end of the third operational amplifier and the 5 pins of the linear optocoupler are connected with the ground, the inverting input end of the third operational amplifier is connected with the 6 pins of the linear optocoupler and one end of a resistor R7, the other end of a resistor R7 is connected with the output end of the third operational amplifier and one end of a resistor R8, the other end of the resistor R8 is connected with one end of a capacitor C2, and the other end of the capacitor C2 is grounded.
In the present application, the embodiment of the isolation current detection method is substantially similar to the embodiment of the isolation current detection circuit, and reference is made to the description of the embodiment of the isolation current detection circuit for relevant points.
It is clear to a person skilled in the art that the solution according to the embodiments of the invention can be implemented by means of software and/or hardware. The "unit" and "module" in this specification refer to software and/or hardware that can perform a specific function independently or in cooperation with other components, where the hardware may be, for example, an FPGA (Field-Programmable Gate Array), an IC (Integrated Circuit), or the like.
In the several embodiments provided in the present application, it should be understood that the disclosed apparatus and method may be implemented in other ways. The above-described device embodiments are merely illustrative, for example, the division of the unit is only a logical functional division, and there may be other division ways in actual implementation, such as: multiple units or components may be combined, or may be integrated into another system, or some features may be omitted, or not implemented. In addition, the coupling, direct coupling or communication connection between the components shown or discussed may be through some interfaces, and the indirect coupling or communication connection between the devices or units may be electrical, mechanical or other forms.
All functional units in the embodiments of the present invention may be integrated into one processing unit, or each unit may be separately used as one unit, or two or more units may be integrated into one unit; the integrated unit can be realized in a form of hardware, or in a form of hardware plus a software functional unit.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. An isolated current sensing circuit, comprising: the circuit comprises a current divider, a differential amplification circuit, a linear optical coupler and a conversion circuit;
the current divider is connected with the differential amplification circuit and used for collecting current signals; the input of the differential amplification circuit is the potential difference between two ends of the current divider, the differential amplification circuit amplifies the potential difference, and the output voltage of the differential amplification circuit is used for driving a linear optocoupler; the linear optocoupler is connected with the conversion circuit, and the conversion circuit is used for converting the output current of the linear optocoupler into voltage.
2. The isolated current sensing circuit of claim 1, further comprising: and the direct current voltage bias module is used for superposing direct current voltage bias on the input end of the differential amplification circuit.
3. The isolated current detection circuit of claim 1 or 2, wherein the shunt is configured to pick up current in a power circuit.
4. The isolated current detection circuit according to any one of claims 1 to 3, wherein the differential amplification circuit comprises: one end of a resistor R2 is connected with one end of the shunt, the other end of a resistor R2 is connected with one end of a capacitor C1, one end of a resistor R1 and the non-inverting input end of the first operational amplifier, and the other end of a capacitor C1 is connected with the other end of a resistor R1; one end of a resistor R3 is connected with the other end of the shunt, the other end of a resistor R3 is connected with the reverse input end of the first operational amplifier, one end of a resistor R4 and one end of a capacitor C3, and the other end of a resistor R4 is connected with the other end of a capacitor C3, the output end of the first operational amplifier and one end of a resistor R5; the other end of the resistor R5 is connected with the reverse input end of the second operational amplifier and the 3 pins of the linear optocoupler, the non-inverting input end of the second operational amplifier is grounded, the output end of the second operational amplifier is connected with one end of the resistor R6, and the other end of the resistor R6 is connected with the 1 pin of the linear optocoupler.
5. The isolated current detection circuit of any one of claims 1-3, wherein the DC voltage bias module is connected to the other end of the capacitor C1 and the other end of the resistor R1.
6. The isolated current detection circuit according to any one of claims 1 to 3, wherein the linear optocoupler is of type HCNR 201-500E.
7. The isolated current detection circuit of any of claims 1-3, wherein the conversion circuit comprises: the non-inverting input end of the third operational amplifier and the 5 pins of the linear optocoupler are connected with the ground, the inverting input end of the third operational amplifier is connected with the 6 pins of the linear optocoupler and one end of a resistor R7, the other end of a resistor R7 is connected with the output end of the third operational amplifier and one end of a resistor R8, the other end of the resistor R8 is connected with one end of a capacitor C2, and the other end of the capacitor C2 is grounded.
8. An isolated current detection method using the isolated current detection circuit according to any one of claims 1 to 7, comprising:
the current divider collects current signals;
the potential difference between two ends of the current divider is used as the input of a differential amplification circuit, the differential amplification circuit amplifies the potential difference, and the output voltage of the differential amplification circuit is used for driving a linear optocoupler;
and the conversion circuit converts the output current of the linear optocoupler into voltage.
9. The isolated current detection method of claim 8, further comprising: and superposing direct-current voltage bias on the input end of the differential amplification circuit.
10. The isolated current detection method of claim 8 or 9, wherein the shunt is used to collect current in a power circuit.
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| CN202111118159.XA CN113866479A (en) | 2021-09-23 | 2021-09-23 | Isolation current detection circuit and method |
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| CN202111118159.XA CN113866479A (en) | 2021-09-23 | 2021-09-23 | Isolation current detection circuit and method |
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| CN207717849U (en) * | 2018-01-09 | 2018-08-10 | 深圳市四方电气技术有限公司 | Short-circuit protection measuring circuit and frequency converter |
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2021
- 2021-09-23 CN CN202111118159.XA patent/CN113866479A/en active Pending
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| CN101661057A (en) * | 2009-09-27 | 2010-03-03 | 哈尔滨理工大学 | Device for implementing power measurement based on resistance sampling by linear optocoupler |
| CN201497766U (en) * | 2009-09-27 | 2010-06-02 | 哈尔滨理工大学 | Current sensor for realizing voltage sampling for current divider by adopting linear photoelectric coupler |
| CN202494720U (en) * | 2012-04-16 | 2012-10-17 | 潍坊长源电力电子有限公司 | Current detection circuit for soft starter |
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