CN106324319A - Direct current voltage and direct current signal sampling circuit - Google Patents

Abstract

The invention relates to a DC voltage and DC current signal sampling circuit, comprising a sampling signal input terminal, an isolated optocoupler and an operational amplifier, the sampling signal input terminal is connected to the primary side of the isolated optocoupler, and the sampling signal input terminal is connected to the primary side of the isolated optocoupler A switch module and a voltage divider module are connected in turn, the secondary side of the isolated optocoupler is connected to the input terminal of the operational amplifier, and the output terminal of the operational amplifier is the sampling signal output terminal of the sampling circuit; the switching module is connected between the sampling signal input terminals A switching branch, on which a switching switch and a switching resistor are arranged in series. The sampling circuit can not only sample the DC voltage signal, but also sample the DC current signal. When the application function is changed, there is no need to replace the circuit board, and the utility model has strong versatility.

Description

A DC voltage and DC current signal sampling circuit

technical field

The invention relates to a DC voltage and DC current signal sampling circuit.

Background technique

The DC signal sampling circuits seen so far can only sample DC voltage signals or DC current signals, and cannot sample both voltage signals and current signals. The application is not flexible and the versatility is poor.

Contents of the invention

The object of the present invention is to provide a DC voltage and DC current signal sampling circuit to solve the problem that the traditional sampling circuit cannot sample both the voltage signal and the current signal.

In order to achieve the above object, the solution of the present invention includes a DC voltage and DC current signal sampling circuit, including a sampling signal input terminal, an isolated optocoupler and an operational amplifier, the sampling signal input terminal is connected to the primary side of the isolated optocoupler, A switch module and a voltage divider module are sequentially connected between the sampling signal input terminal and the primary side of the isolated optocoupler, the secondary side of the isolated optocoupler is connected to the input terminal of the operational amplifier, and the output of the operational amplifier terminal is the sampling signal output terminal of the sampling circuit; the switching module is a switching branch connected between the sampling signal input terminals, and the switching branch is provided with a switching switch and a switching resistor in series.

The switch includes three pins, the first pin and the second pin are set on the switching branch, there is no communication between the first pin and the second pin, the third pin is suspended, and the switching The switch also includes a jumper pin, the switcher is turned on by shorting the first pin and the second pin, and the switcher is turned off by shorting the second pin and the third pin .

A filter module is also connected between the secondary side of the isolation optocoupler and the input terminal of the operational amplifier.

The filter module includes a resistor R5, a resistor R6, a capacitor C2, a capacitor C3 and a capacitor C4, and the connection line between an output terminal of the secondary side of the isolated optocoupler and the corresponding input terminal of the operational amplifier is connected in series. Resistor R5, the resistor R6 is set in series on the connecting line between the other output terminal of the secondary side of the isolated optocoupler and the corresponding input terminal of the operational amplifier, the capacitor C3 is connected between the input terminals of the operational amplifier, and the resistor The connection between R5 and the input terminal of the operational amplifier is grounded through the capacitor C2, and the connection between the resistor R6 and the input terminal of the operational amplifier is grounded through the capacitor C4.

The voltage divider module includes a resistor R2, a resistor R3 and a resistor R4, the resistor R2 is set in series on the connection line between one end of the switch branch and an input end of the primary side of the isolated optocoupler, and the other end of the switch branch The resistor R3 is connected in series with the other input end of the primary side of the isolated optocoupler, and the resistor R4 is connected between the primary sides of the isolated optocoupler.

A capacitor C1 is also connected between the primary sides of the isolation optocoupler.

Magnetic beads are arranged in series on the connecting line between the sampling signal input terminal and the switching module.

The model of the isolated optocoupler is ACPL-C87B.

The model of the operational amplifier is INA128.

The DC voltage and DC current signal sampling circuit provided by the present invention is provided with a switching branch, and a switching switch and a switching resistor are arranged in series on the switching branch. When sampling a DC current signal, the switching switch is turned on, and the DC current signal is switched. After the resistor, a DC voltage is formed at both ends of the resistor, and the voltage is sent to the optocoupler after being divided, and then output after being amplified by the operational amplifier; After the road, the voltage is divided, and then sent to the optocoupler, and then output after being amplified by the operational amplifier. First of all, the sampling circuit can not only sample the DC voltage signal, but also sample the DC current signal. When the application function changes, there is no need to replace the circuit board. Strong anti-interference ability. In addition, the circuit has a simple structure and does not require a very complicated control strategy. When the function is switched, it is only necessary to control the switch. The simple operation can improve the sampling accuracy and ensure the sampling accuracy.

Description of drawings

Figure 1 is a schematic diagram of a DC voltage and DC current signal sampling circuit.

detailed description

The present invention will be described in further detail below in conjunction with the accompanying drawings.

As shown in Figure 1, the DC voltage and DC current signal sampling circuit includes a sampling signal input terminal DC+ and an input terminal DC-, and a switching branch is connected between the input terminal DC+ and the input terminal DC-, and the switching branch is connected in series. There is a switch and a switch resistor R1, the switch is a switch that can be turned on and off, and can be a general knife switch or an electric control switch. This embodiment provides a specific implementation of a switch, as shown in Figure 1, the switch JP1 includes three pins, pin 1 and pin 2 are set on the switch branch, pin 1 and pin 2 They are disconnected, there is no connection, and pin 3 is suspended. In order to control the conduction or shutdown, the switch JP1 also includes a jumper. When the jumper shorts pin 1 and pin 2, pin 1 It is connected with the pin 2 to realize the conduction of the switch JP1; when the jumper shorts the pin 2 and the pin 3, the pin 1 and the pin 2 are disconnected, and the switch JP1 is turned off.

The connection line between the input terminal DC+ and one end of the switching branch is provided with magnetic beads F1 in series, and the connection line between the input terminal DC- and the other end of the switching branch is provided with magnetic beads F2 in series, and the magnetic beads F1 and F2 can initially filter out interference on the sampling signal to prevent the interference signal from entering the sampling circuit.

The input terminal DC+ and the input terminal DC- are connected to the voltage dividing branch through the switching branch, as shown in Figure 1, the voltage dividing branch includes resistor R2, resistor R3 and resistor R4, one end of the switching branch is connected to the isolated optocoupler U1 Resistor R2 is set in series on the connecting line between pin 2 of the primary side, and resistor R3 is set in series on the connecting line between the other end of the switching branch and pin 3 of the primary side of the isolation optocoupler U1, and the isolation optocoupler U1 Connect resistor R4 between pin 2 and pin 3 of the primary side. The voltage divider network formed by the resistor R2, the resistor R3 and the resistor R4 is a step-down network, and the sampling signal is detected by detecting the voltage divider on the resistor R4. In addition, the resistors R2, R3 and R4 are symmetrically distributed, and have a strong ability to resist differential mode interference.

In addition, in order to filter out clutter, a capacitor C1 is connected between pin 2 and pin 3 of the primary side of the isolation optocoupler U1, and the capacitor C1 plays a role of filtering.

In this embodiment, the isolated optocoupler U1 can output the sampled voltage signal at a ratio of 1:1. In this embodiment, the specific model of the isolated optocoupler U1 is ACPL-C87B.

The isolated optocoupler U1 transmits the sampled voltage signal to the operational amplifier U2 after passing through the filter network at a ratio of 1:1. The filter network includes resistor R5, resistor R6, capacitor C2, capacitor C3 and capacitor C4, and a resistor R5 is set in series on the connecting line between pin 7 of the secondary side of the isolation optocoupler U1 and pin 3 of the operational amplifier U2 to isolate the optical A resistor R6 is connected in series between the pin 6 of the secondary side of the coupling U1 and the pin 2 of the operational amplifier U2, a capacitor C3 is connected between the pin 2 and the pin 3 of the operational amplifier U2, and the resistor R5 and the operational amplifier The connection point between pin 3 of U2 is grounded through capacitor C2, and the connection point between resistor R6 and pin 3 of operational amplifier U2 is grounded through capacitor C4.

The part formed by the resistor R5 and the capacitor C2, the part formed by the resistor R6 and the capacitor C4 can filter out the common mode interference, and the part formed by the resistor R5, the resistor R6 and the capacitor C3 can filter out the differential mode interference.

In this embodiment, the amplification factor of the operational amplifier U2 is Moreover, this embodiment provides a specific model of the operational amplifier U2, which is INA128.

The pin 6 of the operational amplifier U2 is the output terminal of the operational amplifier, and the pin 6 is the output terminal of the sampling circuit for outputting the sampling signal.

The DC voltage and DC current signal sampling circuit can not only sample the DC voltage signal, but also sample the DC current signal. In addition, when sampling a voltage signal or a current signal, since the connection between the sampling circuit and the sampled object belongs to conventional technology, no specific description is given here.

When sampling the DC current signal, make the jumper short the pin 1 and pin 2 of the switch JP1, the DC current signal Idc to be measured passes through the resistor R1 to form a voltage Udc, and the voltage Udc passes through the resistor R2, resistor R3 and resistor R4. The voltage divider network steps down the voltage, and the voltage after the step-down is reflected at both ends of the resistor R4, and the voltage at both ends of the resistor R4 is sent to the isolated optocoupler U1; the isolated optocoupler U1 processes the voltage at both ends of the resistor R4 at a ratio of 1:1 And output, after passing through the filtering network, it is transmitted to the operational amplifier U2; the operational amplifier U2 amplifies the sampling voltage and then outputs it.

When sampling the DC voltage signal, make the jumper short the pin 2 and pin 3 of the switch JP1, the switch is disconnected, no current flows on the switching branch, and the DC current signal Udc to be measured passes through the resistance R2 and the resistance R3 The voltage divider network composed of resistor R4 is used to reduce the voltage, and the voltage after step-down is reflected at both ends of resistor R4, and the voltage at both ends of resistor R4 is sent to the isolated optocoupler U1; the isolated optocoupler U1 is 1:1 to the voltage at both ends of resistor R4 The ratio is processed and output, and then transmitted to the operational amplifier U2 after passing through the filter network; the operational amplifier U2 amplifies the sampling voltage and outputs it.

In the above-mentioned embodiment, several devices for filtering out interference are provided in the sampling circuit, and these devices for filtering out interference are optimized implementation modes for the present invention, and these devices can be omitted as other implementation modes .

Specific embodiments have been given above, but the present invention is not limited to the described embodiments. The basic idea of the present invention lies in the above-mentioned basic scheme. For those of ordinary skill in the art, according to the teaching of the present invention, it does not need to spend creative labor to design various deformation models, formulas, and parameters. Changes, modifications, substitutions and variations to the implementations without departing from the principle and spirit of the present invention still fall within the protection scope of the present invention.

Claims (9)

1. a DC voltage and DC current signal sample circuit, it is characterised in that include sampled signal input, be optically isolated Coupling and operational amplifier, described sampled signal input connect described isolation optocoupler former limit, described sampled signal input with Being connected with handover module and division module between the former limit of described isolation optocoupler in turn, the secondary of described isolation optocoupler connects described The input of operational amplifier, the outfan of described operational amplifier is the sampled signal outfan of described sample circuit；Described Handover module is the handoff leg connected between sampled signal input, and in described handoff leg, string is provided with switching switch And convert resistance.

DC voltage the most according to claim 1 and DC current signal sample circuit, it is characterised in that described switching is opened Pass includes that three pins, the first pin and the second pin are arranged in described handoff leg, between the first pin and the second pin Not connection, three-prong is unsettled, and described switching switch also includes a bouncing pilotage, and described bouncing pilotage is by short circuit the first pin and the Two pins realize the conducting of this switching switch, realize this switching switch-off by short circuit the second pin and three-prong.

DC voltage the most according to claim 1 and DC current signal sample circuit, it is characterised in that described in be optically isolated It is also associated with filtration module between secondary and the input of described operational amplifier of coupling.

DC voltage the most according to claim 3 and DC current signal sample circuit, it is characterised in that described filtering mould Block includes resistance R5, resistance R6, electric capacity C2, electric capacity C3 electric capacity C4, and an outfan of the secondary of described isolation optocoupler is with described On connection line between the input that operational amplifier is corresponding, string sets described resistance R5, another of the secondary of described isolation optocoupler On connection line between the input that individual outfan is corresponding with operational amplifier, string sets described resistance R6, operational amplifier defeated Enter and connect described electric capacity C3 between end, by electric capacity C2 ground connection between resistance R5 and the input of operational amplifier, resistance R6 with By electric capacity C4 ground connection between the input of operational amplifier.

DC voltage the most according to claim 1 and DC current signal sample circuit, it is characterised in that described dividing potential drop mould Block includes resistance R2, resistance R3 and resistance R4, between an input on one end of handoff leg and the former limit of isolation optocoupler On connection line, string sets described resistance R2, between another input on the other end of handoff leg and the former limit of isolation optocoupler On connection line, string sets described resistance R3, connects described resistance R4 between the former limit of isolation optocoupler.

DC voltage the most according to claim 5 and DC current signal sample circuit, it is characterised in that described in be optically isolated It is also associated with electric capacity C1 between the former limit of coupling.

DC voltage the most according to claim 1 and DC current signal sample circuit, it is characterised in that described sampling is believed On connection line number between input and handover module, string is provided with magnetic bead.

DC voltage the most according to claim 1 and DC current signal sample circuit, it is characterised in that described in be optically isolated The model of coupling is ACPL-C87B.

DC voltage the most according to claim 1 and DC current signal sample circuit, it is characterised in that described computing is put The model of big device is INA128.