CN218180954U

CN218180954U - Microampere current detection circuit for high-voltage output

Info

Publication number: CN218180954U
Application number: CN202220634086.3U
Authority: CN
Inventors: 黄建生; 邹祖娇
Original assignee: Ecu Electronics Industrial Co ltd
Current assignee: Ecu Electronics Industrial Co ltd
Priority date: 2022-03-22
Filing date: 2022-03-22
Publication date: 2022-12-30
Anticipated expiration: 2032-03-22

Abstract

The utility model discloses a microampere current detection circuit for high-voltage output in the field of current detection, which comprises a switching power supply, a high-voltage module, a differential amplification circuit module, a sampling circuit module, a feedback network module and a reflection target; the high-voltage module is used for converting a direct-current signal provided by the switching power supply into a high-frequency alternating-current signal, boosting and rectifying the high-frequency alternating-current signal, outputting direct-current high voltage to the reflecting target, collecting a microampere current signal flowing through the reflecting target by the sampling circuit module, converting the microampere current signal into a voltage signal and outputting the voltage signal to the differential amplification module; the differential amplification module mainly comprises an operational amplification chip N1 and a compensation network, wherein the input end of the operational amplification chip N1 is connected with the output of the sampling circuit module, and the output end of the operational amplification chip N1 is connected with the input end of the feedback network module and is also connected with a processor; the compensation network includes at least two resistor-capacitor networks and a switch. The utility model has the advantages of detect that the precision is high, wide range and reliable and stable.

Description

Microampere current detection circuit for high-voltage output

Technical Field

The utility model relates to a current detection field specifically is a microampere current detection circuit for high voltage output.

Background

With the development of science and technology, high-voltage power supplies are widely applied to the fields of medical treatment, security inspection, industrial detection and the like, and particularly, for the detection of the quality of lithium batteries, the voltage output by the high-voltage power supplies is higher and higher, and the current is very small. The traditional high-voltage power supply outputs current to detect the current of the reflecting target in a current sensor mode, and has low precision, narrow current detection range and poor stability.

SUMMERY OF THE UTILITY MODEL

An object of the utility model is to provide a microampere current detection circuit for high-voltage output makes its microampere current detection precision high, wide range and reliable and stable.

In order to achieve the above object, the utility model provides a following technical scheme:

a microampere current detection circuit for high-voltage output comprises a switching power supply, a high-voltage module, a differential amplification circuit module, a sampling circuit module, a feedback network module and a reflection target; the high-voltage module is used for converting a direct-current signal provided by the switching power supply into a high-frequency alternating-current signal, boosting and rectifying the high-frequency alternating-current signal, outputting direct-current high voltage to the reflecting target, and the sampling circuit module is used for collecting microampere current signals flowing through the reflecting target, converting the microampere current signals into voltage signals and outputting the voltage signals to the differential amplification module; the differential amplification module mainly comprises an operational amplification chip N1 and a compensation network, wherein the input end of the operational amplification chip N1 is connected with the output of the sampling circuit module, and the output end of the operational amplification chip N1 is connected with the input end of the feedback network module and is also connected with a processor; the compensation network comprises at least two resistance-capacitance networks and switches, and the processor switches the states of the switches according to the output of the operational amplification chip N1 so as to control the number of the accessed resistance-capacitance networks.

In some embodiments, the switching power supply comprises power supplies HV1, HV2 for dc output; the high-voltage module comprises MOS (metal oxide semiconductor) tubes Q1 and Q2, a high-frequency transformer T1 and a rectifying circuit, the switching power supply outputs direct current signals to the MOS tubes Q1 and Q2, the MOS tubes Q1 and Q2 output high-frequency alternating current signals through PWM (pulse width modulation) control, the high-frequency transformer T1 boosts the high-frequency alternating current signals and then outputs the high-frequency alternating current signals to the rectifying circuit, and the rectifying circuit outputs direct current high voltage.

In some embodiments, the switching power supply comprises power supplies HV1, HV2 for dc output; the high-frequency transformer T1 comprises primary windings T11 and T12 and a secondary winding T21, and the rectifying circuit comprises capacitors C1 and C2 and high-voltage diodes D1 and D2; the dotted terminal of the winding T11 is connected with the drain electrode of the MOS tube Q1, the dotted terminal of the winding T12 is connected with the power supply HV1, the dotted terminal is connected with the drain electrode of the MOS tube Q2, the source electrodes of the MOS tubes Q1 and Q2 are both connected with the power ground, the grid electrode of the MOS tube Q1 is connected with a PWM1 signal, and the grid electrode of the MOS tube Q2 is connected with a PWM2 signal; the dotted terminal of the winding T21 is connected with the first terminal of the capacitor C1, the second terminal of the capacitor C1 is connected with the cathode of the high-voltage diode D1 and the anode of the high-voltage diode D2, the dotted terminal of the winding T21 is connected with the anode of the high-voltage diode D1 and the first terminal of the capacitor C2, the second terminal of the capacitor C2 is connected with the cathode of the high-voltage diode D2 and the first terminal of the resistor R1, and the second terminal of the resistor R1 is connected with the ground through the reflection target R0.

In some embodiments, the sampling circuit module includes resistors R2 and R3, a first end of the resistor R2 is connected to the alias end of the winding T21, a second end of the resistor R3 is connected to the first end of the resistor R3, and a second end of the resistor R3 is connected to the ground.

In some embodiments, the output end of the operational amplification chip N1 is further connected to a resistance value adjusting circuit, the resistance value adjusting circuit includes a clamping circuit mainly composed of a resistor R8, a potentiometer RP1 and a diode D3, the output end of the operational amplification chip N1 is connected to an anode of the diode D3 through a series resistor R7, the resistor R8 and the potentiometer RP1 are connected in series between an external power supply and a power ground, and a cathode of the diode D3 is connected to a common end of the resistor R8 connected to the potentiometer RP 1.

In some embodiments, the feedback network module includes an operational amplifier chip N2 and resistors R9, R10, and R11, a non-inverting input terminal of the operational amplifier chip N2 is connected to the resistor R7 through the resistor R9, an inverting input terminal of the operational amplifier chip N is connected to an output terminal of the operational amplifier chip N through the resistor R10, and the resistor R11 is connected between the output terminal and a power ground.

Has the advantages that: the utility model discloses can be used to high-voltage output's microampere current detection circuit. The switch power supply generates high-voltage output through the high-voltage module, converts the current model flowing through the reflection target into a voltage signal through the reflection target and the sampling circuit module, and sends the voltage signal to the differential amplification circuit module to convert a weak voltage signal into a linear amplified voltage signal, so that microampere current detection in a wide range is realized, and the voltage signal in a corresponding proportion range can be realized through the feedback network. The utility model has the advantages of detect that the precision is high, wide range and reliable and stable.

Drawings

Fig. 1 is a block diagram of a microampere current detection circuit for high voltage output according to the present invention;

fig. 2 is a circuit schematic of a high voltage module of the present disclosure;

fig. 3 is a schematic diagram of a sampling circuit module disclosed in the present invention;

fig. 4 is a schematic diagram of a differential amplifier circuit module disclosed in the present invention;

FIG. 5 is a schematic diagram of a feedback network module of the present disclosure;

fig. 6 is a timing diagram of the driving signal of the high voltage module disclosed in the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative work belong to the protection scope of the present invention.

Referring to fig. 1, a microampere current detection circuit for high voltage output includes a switching power supply, a high voltage module, a differential amplification circuit module, a sampling circuit module, a feedback network module, and a reflective target.

The high-voltage module comprises MOS (metal oxide semiconductor) tubes Q1 and Q2, a high-frequency transformer T1 and a rectifying circuit, the switching power supply outputs direct current signals to the MOS tubes Q1 and Q2, the MOS tubes Q1 and Q2 output high-frequency alternating current signals through PWM (pulse width modulation) control, the high-frequency transformer T1 boosts the high-frequency alternating current signals and outputs the boosted high-frequency alternating current signals to the rectifying circuit, and the rectifying circuit outputs direct current high voltage; the sampling circuit module collects microampere current signals flowing through the reflecting target, converts the microampere current signals into weak voltage signals and outputs the weak voltage signals to the differential amplification module.

The differential amplification module mainly comprises an operational amplification chip N1, a compensation network and a resistance value adjusting circuit, wherein the input end of the operational amplification chip N1 is connected with the output of the sampling circuit module, the output end of the operational amplification chip N1 is connected with the input ends of the feedback network module and the resistance value adjusting circuit, and the operational amplification chip is also connected with a processor such as a single chip microcomputer; the compensation network comprises at least two resistance-capacitance networks and a switch, the processor matches the output value with different gains preset in the processor by detecting the output of the operational amplification chip N1, so that the other number of the resistance-capacitance networks needing to be switched in is determined, and the state of the selector switch is controlled. The number of the switches is one less than that of the resistor-capacitor networks, the output precision of the differential amplification circuit is higher as the number of the resistor-capacitor networks is larger, meanwhile, the detection in a wider range can be realized under the same sampling current, and the detection precision is constant under the range corresponding to the gain of the processor. The differential amplification circuit module converts the weak voltage signal into a linear, high-precision and range-adjustable voltage signal, and then a voltage signal with a corresponding proportion is formed through the feedback network module. Therefore, high-precision and wide-range detection of high-voltage output microampere current is realized, and the stability is high.

Referring to fig. 2, the switching power supply includes power supplies HV1, HV2 for direct current output; the high-frequency transformer T1 comprises primary windings T11 and T12 and a secondary winding T21, and the rectifying circuit comprises capacitors C1 and C2 and high-voltage diodes D1 and D2; the dotted terminal of the winding T11 is connected with the drain electrode of the MOS tube Q1, the dotted terminal of the winding T12 is connected with the power supply HV1, the dotted terminal is connected with the drain electrode of the MOS tube Q2, the source electrodes of the MOS tubes Q1 and Q2 are both connected with the power supply ground, the grid electrode of the MOS tube Q1 is connected with a PWM1 signal, and the grid electrode of the MOS tube Q2 is connected with a PWM2 signal; the dotted terminal of the winding T21 is connected with the first terminal of the capacitor C1, the second terminal of the capacitor C1 is connected with the cathode of the high-voltage diode D1 and the anode of the high-voltage diode D2, the dotted terminal of the winding T21 is connected with the anode of the high-voltage diode D1 and the first terminal of the capacitor C2, the second terminal of the capacitor C2 is connected with the cathode of the high-voltage diode D2 and the first terminal of the resistor R1, and the second terminal of the resistor R1 is connected with the ground through the reflection target R0.

The high-voltage module respectively drives the MOS transistors Q1 and Q2 by two paths of PWM1 and PWM2 driving signals, and fig. 6 is a timing diagram of the high-voltage module generating high-voltage output to control the MOS transistors Q1 and Q2. The PWM1 signal and the PWM2 signal are +15V pulse signals, the pulse frequency is 50kHz, the phase difference is 180 degrees, and the duty ratio is 30 percent respectively. The value of the duty cycle may be varied according to actual requirements. MOS pipe Q1, Q2 convert power HV1 direct current into high frequency alternating current, boost through high frequency transformer T1 and convert into high frequency high voltage alternating current, rethread high voltage capacitor C1, high voltage capacitor C2, high voltage diode V1, high voltage diode V2, through twice the pressure rectification high voltage direct current that flows, the high voltage direct current is acted on reflection target R0 through current-limiting resistor R1. When the reflective target R0 is ignited, the current limiting resistor R1 plays a role in protection, so that a power supply is not damaged.

In some embodiments, the model of the MOS transistors Q1 and Q2 can be selected as RFB4321PBF, the model of the capacitors C1 and C2 can be selected as CT81Y5U10KV222M, and the model of the diodes D1 and D2 can be selected as 2CLG0520.

In other embodiments, the electronic components may be selected from other types according to actual situations.

As shown in fig. 3, the sampling circuit module includes resistors R2 and R3, a first end of the resistor R2 is connected to the alias end of the winding T21, a second end is connected to the first end of the resistor R3, and a second end of the resistor R3 is connected to ground. The current flowing through the reflective target can be determined by the voltage drop across R2. When the high voltage module 2 outputs high voltage, the reflecting target 5 and the sampling circuit module 3 form a loop, and a voltage drop is formed at two ends of the resistor R2, so that the current flowing through the reflecting target 5 is collected by the sampling circuit module 3, and microampere current signals flowing through the reflecting target 5 are converted into weak voltage signals by the resistor R2 and are sent to the differential amplification circuit.

In some preferred embodiments, the model of the operational amplifier chip N1 in the differential amplifier circuit is INA326. In other embodiments, the model of the INA327 and the like capable of achieving the detection with equal high precision may be changed according to actual conditions. Referring to fig. 4, taking INA326 as an example, pin 2 of the operational amplifier chip N1 is connected to the second end of the resistor R2, pin 3 is connected to the opposite end of the winding T21, a resistor R4 is connected between pin 1 and pin 8, pin 7 is connected to the power source HV2, and pin 4 is connected to the power source ground. In this embodiment, two resistor-capacitor networks are provided, one of the two resistor-capacitor networks includes a capacitor C3 and a resistor R6 connected in parallel, the other resistor-capacitor network includes a capacitor C4 and a resistor R5 connected in parallel, one end of each of the capacitors C3 and C4 and one end of each of the resistors R5 and R6 are connected to the pin 5 of the operational amplifier chip N1, the other end of each of the capacitors C3 and R6 is connected to the power ground, and the switch K1 is connected between the two resistor-capacitor networks. The operational amplification chip N1 amplifies the voltage signal output by the sampling circuit module, the processor judges the corresponding gain according to the value of the voltage signal, switches the switch state of the switch K1, controls the number of the input resistor-capacitor networks, and selects the microampere current detection range (0 muA-10 mA), thereby achieving wide-range and high-precision microampere current detection. For example, when the microampere current generated on the reflective target R0 is 0 μ a to 1mA, the voltage signal output by the sampling circuit module is small, the processor determines and selects the gain corresponding thereto, the switch 1 is turned off, compensation is performed only through one resistor-capacitor network, and finally the microampere current detection value output by the feedback network module can be accurate to 0.1, which is equivalent to realizing high-accuracy detection and realizing detection in a wider range under the same sampling current. When the current generated on the reflecting target R0 is 1 mA-10 mA, the processor can judge to close the switch 1, and the two resistance-capacitance networks are used for high-precision compensation, so that when the current of a sampling object is large, the microampere current can still be accurately detected in a wide range.

The resistance value adjusting circuit comprises a clamping circuit mainly composed of a resistor R8, a potentiometer RP1 and a diode D3, and any value (> 0.7V) can be clamped by changing the resistance value of the RP 1. The pin 6 of the operational amplification chip N1 is connected with the anode of the diode D3 through the series resistor R7, the resistor R8 and the potentiometer RP1 are connected between an external power supply and a power ground in series, and the cathode of the diode D3 is connected with the common end of the resistor R8 connected with the potentiometer RP 1. The resistance value adjusting circuit can prevent the output voltage from being too high to influence a post-stage circuit by clamping the output voltage. Any value can be obtained by changing the resistance value of RP1, and the range is (the maximum value of 0-6 pin output of the operational amplification chip N1)

As shown in fig. 5, the feedback network module includes an operational amplifier chip N2, resistors R9, R10, and R11, wherein a non-inverting input terminal of the operational amplifier chip N2 is connected to the resistor R7 through the resistor R9, an inverting input terminal thereof is connected to an output terminal thereof through the resistor R10, and the resistor R11 is connected between the output terminal and a power ground. The output end of the operational amplification chip N2 outputs a proportional voltage signal VOUT, and the output voltage signal VOUT can be adjusted by changing the resistance values of the resistors R10 and R11, so that high-precision and wide-range detection of high-voltage output microampere current is realized, and the stability is high.

Although the present description is described in terms of embodiments, not every embodiment includes only a single embodiment, and such description is for clarity only, and those skilled in the art should be able to integrate the description as a whole, and the embodiments can be appropriately combined to form other embodiments as will be understood by those skilled in the art.

Therefore, the above description is only for the preferred embodiment of the present application and is not intended to limit the scope of the present application; all changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.

Claims

1. A microampere current detection circuit for high-voltage output is characterized by comprising a switching power supply, a high-voltage module, a differential amplification circuit module, a sampling circuit module, a feedback network module and a reflection target; the high-voltage module is used for converting a direct-current signal provided by a switching power supply into a high-frequency alternating-current signal, boosting and rectifying the high-frequency alternating-current signal, outputting direct-current high voltage to the reflecting target, and the sampling circuit module is used for collecting a microampere current signal flowing through the reflecting target, converting the microampere current signal into a voltage signal and outputting the voltage signal to the differential amplification module;

the differential amplification module mainly comprises an operational amplification chip N1 and a compensation network, wherein the input end of the operational amplification chip N1 is connected with the output of the sampling circuit module, and the output end of the operational amplification chip N1 is connected with the input end of the feedback network module and is also connected with a processor; the compensation network comprises at least two resistance-capacitance networks and switches, and the processor switches the states of the switches according to the output of the operational amplification chip N1 so as to control the number of the accessed resistance-capacitance networks.

2. A microampere current detection circuit for high voltage output according to claim 1, characterized in that the switching power supply comprises power supplies HV1, HV2 for direct current output; the high-voltage module comprises MOS (metal oxide semiconductor) tubes Q1 and Q2, a high-frequency transformer T1 and a rectifying circuit, the switching power supply outputs direct current signals to the MOS tubes Q1 and Q2, the MOS tubes Q1 and Q2 output high-frequency alternating current signals through PWM (pulse width modulation) control, the high-frequency transformer T1 boosts the high-frequency alternating current signals and then outputs the high-frequency alternating current signals to the rectifying circuit, and the rectifying circuit outputs direct current high voltage.

3. The microampere current detection circuit for high voltage output according to claim 2, wherein the high frequency transformer T1 comprises primary windings T11, T12 and a secondary winding T21, the rectifier circuit comprises capacitors C1, C2 and high voltage diodes D1, D2; the homonymous end of the winding T11 is connected with the drain electrode of the MOS tube Q1, the homonymous end of the winding T12 is connected with the power supply HV1, the synonym end is connected with the drain electrode of the MOS tube Q2, the source electrodes of the MOS tubes Q1 and Q2 are both connected with the power ground, the grid electrode of the MOS tube Q1 is connected with the PWM1 signal, and the grid electrode of the MOS tube Q2 is connected with the PWM2 signal; the dotted terminal of the winding T21 is connected with the first terminal of the capacitor C1, the second terminal of the capacitor C1 is connected with the cathode of the high-voltage diode D1 and the anode of the high-voltage diode D2, the dotted terminal of the winding T21 is connected with the anode of the high-voltage diode D1 and the first terminal of the capacitor C2, the second terminal of the capacitor C2 is connected with the cathode of the high-voltage diode D2 and the first terminal of the resistor R1, and the second terminal of the resistor R1 is connected with the ground through the reflection target R0.

4. The microampere current detection circuit for high voltage output according to claim 3, wherein the sampling circuit module comprises resistors R2 and R3, a first end of the resistor R2 is connected with a different name end of the winding T21, a second end of the resistor R3 is connected with a first end of the resistor R3, and a second end of the resistor R3 is connected with the ground.

5. The microampere current detection circuit for high voltage output according to claim 1 or 4, wherein a resistance value adjusting circuit is further connected to the output end of the operational amplification chip N1, the resistance value adjusting circuit comprises a clamping circuit mainly composed of a resistor R8, a potentiometer RP1 and a diode D3, the output end of the operational amplification chip N1 is connected with the anode of the diode D3 through a series resistor R7, the resistor R8 and the potentiometer RP1 are connected in series between an external power supply and a power ground, and the cathode of the diode D3 is connected to the common end of the resistor R8 and the potentiometer RP 1.

6. The microampere current detection circuit for high-voltage output according to claim 5, wherein the feedback network module comprises an operational amplifier chip N2, resistors R9, R10 and R11, wherein a non-inverting input terminal of the operational amplifier chip N2 is connected with a resistor R7 through the resistor R9, an inverting input terminal of the operational amplifier chip is connected with an output terminal of the operational amplifier chip through the resistor R10, and the resistor R11 is connected between the output terminal and a power ground.