CN215005588U - Current detection device for secondary side loop of mutual inductor - Google Patents
Current detection device for secondary side loop of mutual inductor Download PDFInfo
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Abstract
The application discloses mutual-inductor secondary side return current detection device includes: the device comprises a voltage acquisition circuit, a current amplification circuit, a phase modulator and a compensation control circuit; the voltage acquisition circuit is connected between two ends of the secondary side of the mutual inductor in series, the input end and the output end of the current amplification circuit are respectively connected with the output end of the voltage acquisition circuit and the input end of the current amplification circuit, the output end of the current amplification circuit is connected with the input end of the phase modulator, the input end and the output end of the phase modulator are respectively connected with the output end of the current amplification circuit and the input end of the compensation control circuit, and the output end of the compensation control circuit is connected with one end of the secondary side of the mutual inductor. The method and the device can realize the reverse injection of the compensation current of the secondary side of the mutual inductor on the basis of not increasing the auxiliary winding, thereby improving the measurement precision of the loop current of the secondary side of the mutual inductor.
Description
Technical Field
The utility model relates to an electric power system technical field, in particular to mutual-inductor secondary side return current detection device.
Background
The power system generally adopts the current transformer with a single-turn through structure as a micro-current sensor, so that the original grounding mode of the power equipment is not changed, the operation safety of the detected equipment is ensured, and meanwhile, the monitoring system can also play a role in high-voltage isolation. The current sensor realizes energy transfer by primary side current and secondary side current through a magnetic induction coupling principle, and errors influencing output results are mainly caused by exciting current required by establishing magnetic flux in an iron core. If the magnetic current is made to be zero, the excitation magnetic potential is zero, the error is zero, and the current sensor works in a zero magnetic flux state. In fact, there is no exciting current, no magnetic flux exists in the core, and energy on the primary side and the secondary side cannot be transmitted.
In the prior art, in order to measure the secondary side loop current in the "zero magnetic flux" state, an additional auxiliary winding is generally required to be added, and the error caused by the excitation current is eliminated by injecting a compensation current into the auxiliary winding. When the auxiliary winding is adopted for compensating current injection, the auxiliary winding needs to be added on the basis of the structure of the mutual inductor, and the operation is complex, time-consuming and labor-consuming. Therefore, how to inject the compensation current without increasing the auxiliary winding is a technical problem to be solved by those skilled in the art.
SUMMERY OF THE UTILITY MODEL
In view of this, the utility model aims to provide a mutual-inductor secondary side return current detection device can realize the reverse injection of the compensating current of mutual-inductor secondary side on the basis that does not increase auxiliary winding to improve the measurement accuracy of mutual-inductor secondary side return current. The specific scheme is as follows:
in order to solve the technical problem, the utility model provides a mutual-inductor secondary side return current detection device, include: the device comprises a voltage acquisition circuit, a current amplification circuit, a phase modulator and a compensation control circuit;
the voltage acquisition circuit is connected between two ends of the secondary side of the mutual inductor in series, the input end and the output end of the current amplification circuit are respectively connected with the output end of the voltage acquisition circuit and the input end of the current amplification circuit, the output end of the current amplification circuit is connected with the input end of the phase modulator, the input end and the output end of the phase modulator are respectively connected with the output end of the current amplification circuit and the input end of the compensation control circuit, and the output end of the compensation control circuit is connected with one end of the secondary side of the mutual inductor;
the voltage acquisition circuit is used for acquiring voltages at two ends of a secondary side of the mutual inductor, the current amplification circuit is used for generating compensation current with the same waveform as the output current of the voltage acquisition circuit, the phase modulator is used for carrying out phase adjustment on the compensation current, and the compensation control circuit is used for controlling the current amplification circuit to generate the compensation current with the same waveform as the output current of the voltage acquisition circuit.
Optionally, the device for detecting a secondary side loop current of the transformer further includes a controller and a waveform display, wherein:
the input end of the controller is respectively connected with the voltage acquisition circuit and the compensation control circuit, and the output end of the controller is connected with the waveform display.
Optionally, the voltage obtaining circuit includes a voltage measuring circuit, a voltage-current converting circuit and a voltage sampling circuit, wherein:
the voltage measuring circuit comprises a first amplifier and a first resistor connected to two ends of the first amplifier, the first resistor is connected between two ends of the secondary side of the mutual inductor in series, and one end of the secondary side of the mutual inductor is grounded; the input end of the voltage-current conversion circuit is connected with the output end of the first amplifier; the voltage sampling circuit comprises a second resistor and a first ADC (analog-to-digital converter) used for converting the voltage at two ends of the second resistor into a digital signal, wherein the second resistor is connected between the output end of the voltage-current conversion circuit and the input end of the current amplification circuit in series.
Optionally, the compensation control circuit includes a third resistor and a second ADC for converting a voltage across the third resistor into a digital signal.
Optionally, the current detection device of the secondary side loop of the transformer further includes a voltage-current conversion circuit, and an input end and an output end of the voltage-current conversion circuit are respectively connected to an output end of the current amplification circuit and an input end of the phase modulator.
Optionally, the voltage-current conversion circuit includes: the amplifier comprises a first amplifier, a second amplifier, a third amplifier, a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor, an eighth resistor and a ninth resistor, wherein the resistance of the fifth resistor is equal to that of the fourth resistor;
the positive phase input end of the second amplifier is connected with the voltage to be converted through the fourth resistor; the inverting input end of the second amplifier is grounded through the fifth resistor; the output end of the second amplifier is connected with the positive-phase input end of the third amplifier, the self-inverting input end of the second amplifier is connected through the sixth resistor, and the positive-phase input end of the fourth amplifier is connected through the eighth resistor; the output end of the third amplifier is in short circuit with the inverting input end of the third amplifier, and is connected with the non-inverting input end of the fourth amplifier through the ninth resistor; the inverting input end of the fourth amplifier is connected with the non-inverting input end of the second amplifier through the seventh resistor; the output end of the fourth amplifier is in short circuit with the self inverting input end; and the positive phase input end of the fourth amplifier is the output end of the converted current.
Optionally, the current amplifying circuit includes: the gain control circuit comprises a first current source, a second current source, a first controllable switch, a second controllable switch, a third controllable switch, a fourth controllable switch, a fifth controllable switch and a gain adjusting resistor;
a first end of the first controllable switch is connected with an input voltage through the first current source, a second end of the first controllable switch is connected with a first end of the second controllable switch, and a control end of the first controllable switch is connected with a control end of the third controllable switch; the control end of the second controllable switch is connected with the control end of the fourth controllable switch and is grounded through the second current source, and the second end of the second controllable switch is grounded; a first end of the third controllable switch is connected with the input voltage through the gain adjusting resistor, a second end of the third controllable switch is connected with a first end of the fourth controllable switch, and a second end of the fourth controllable switch is grounded; the control end of the fifth controllable switch is connected with the first end of the first controllable switch, the first end of the fifth controllable switch is connected with the input voltage, and the second end of the fifth controllable switch is connected with the control ends of the second controllable switch and the fourth controllable switch.
Optionally, the current amplifying circuit is a current mirror for adjusting a current gain.
Optionally, the first amplifier is an operational amplifier CA3130, and the controller is a DSP processor.
Optionally, the first ADC and the second ADC are ADS 7835.
The application discloses a current detection device for a secondary side loop of a mutual inductor, which comprises a voltage acquisition circuit, a current amplification circuit, a phase modulator and a compensation control circuit; the voltage acquisition circuit is connected between two ends of the secondary side of the mutual inductor in series, the input end and the output end of the current amplification circuit are respectively connected with the output end of the voltage acquisition circuit and the input end of the current amplification circuit, the output end of the current amplification circuit is connected with the input end of the phase modulator, the input end and the output end of the phase modulator are respectively connected with the output end of the current amplification circuit and the input end of the compensation control circuit, and the output end of the compensation control circuit is connected with one end of the secondary side of the mutual inductor. This application passes through the voltage acquisition circuit acquires the voltage at mutual-inductor secondary side both ends, compensation control circuit control current amplifier circuit produce with the compensating current that voltage acquisition circuit's output current's waveform is the same, the phase modifier is right compensating current carries out phase adjustment, and passes through compensating current reverse injection after compensating control circuit will adjust extremely the one end of mutual-inductor secondary side can realize the compensating current's of mutual-inductor secondary side reverse injection on the basis that does not increase auxiliary winding, also can realize simultaneously compensating current aligns with the electromotive force phase at secondary side both ends to improve mutual-inductor secondary side return current's measurement accuracy.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required to be used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.
Fig. 1 is a schematic circuit diagram of a secondary side loop current detection device of a transformer according to the present invention;
fig. 2 is a structural diagram of a voltage-current conversion circuit provided by the present invention;
fig. 3 is a structural diagram of a current amplifying circuit according to 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.
The utility model discloses a core provides a mutual-inductor secondary side return current detection device, can realize the compensating current's of mutual-inductor secondary side reverse injection on the basis that does not increase auxiliary winding, also can realize simultaneously compensating current aligns with the electromotive force phase place at secondary side both ends to improve mutual-inductor secondary side return current's measurement accuracy. In order to make the technical solution of the present invention better understood, the present invention will be further described in detail with reference to the accompanying drawings and the detailed description.
Fig. 1 is a schematic circuit diagram of a secondary side loop current detection device of a transformer according to the present invention, and a circuit structure of the secondary side loop current detection device of the transformer shown in fig. 1 is described below.
The embodiment of the utility model discloses mutual-inductor secondary side return current detection device, include: voltage acquisition circuit, current amplification circuit 03, phase modulator 05 and compensation control circuit 06, wherein, voltage acquisition circuit concatenates between the mutual-inductor secondary side both ends, current amplification circuit 03's input and output respectively with voltage acquisition circuit's output with current amplification circuit 03's input is connected, current amplification circuit 03's output is connected the input of phase modulator 05, the input and the output of phase modulator 05 respectively with current amplification circuit 03's output with compensation control circuit 06's input is connected, compensation control circuit 06's output with the one end of mutual-inductor secondary side is connected. It is understood that the voltage obtaining circuit is configured to obtain voltages at two ends of the secondary side of the transformer, and the current amplifying circuit 03 is configured to generate a compensation current having the same waveform as the output current of the voltage obtaining circuit, and may be an adjustable current source. The phase modulator 05 is used to phase-modulate the compensation current so that the phases are strictly opposite in order to achieve a "zero flux". The compensation control circuit 06 is configured to control the current amplifying circuit 03 to generate a compensation current having the same waveform as the output current of the voltage obtaining circuit. Meanwhile, the compensation current is reversely input to one end of the secondary winding, for example, one end of the two ends of the secondary winding connected to the port2 port, through the compensation control circuit 06 and then through the port 3.
The voltage acquisition circuit can comprise a voltage measurement circuit 01, a voltage-current conversion circuit 02 and a voltage sampling circuit 04, wherein the voltage measurement circuit 01 comprises a first amplifier A1 and a first resistor R connected to two ends of the first amplifier A1, the first resistor R is connected between two ends of the secondary side of the transformer in series, and one end of the secondary side of the transformer is grounded; the input end of the voltage-current conversion circuit 02 is connected with the output end of the first amplifier A1; the voltage sampling circuit 04 comprises a second resistor Rd and a first ADC for converting voltages at two ends of the second resistor Rd into digital signals, and the second resistor Rd is connected in series between the output end of the voltage-current conversion circuit 02 and the input end of the current amplification circuit 03. The first amplifier a1 is a differential amplifier a1 for amplifying a weak electrical signal on the secondary side, and further the differential amplifier a1 is an operational amplifier CA3130 with high input impedance. Two ports 1 and 2 of the first resistor R are connected to two ends of a secondary winding of the transformer at the same time, and one end of the secondary winding port1 is grounded. The output of the voltage-current conversion circuit 02 is converted into the current I, which is independent of the load at the output and is only proportional to the output voltage of the differential amplifier a 1.
Therefore, the embodiment of the application discloses a current detection device for a secondary side loop of a mutual inductor, which comprises a voltage acquisition circuit, a current amplification circuit, a phase modulator and a compensation control circuit; the voltage acquisition circuit is connected between two ends of the secondary side of the mutual inductor in series, the input end and the output end of the current amplification circuit are respectively connected with the output end of the voltage acquisition circuit and the input end of the current amplification circuit, the output end of the current amplification circuit is connected with the input end of the phase modulator, the input end and the output end of the phase modulator are respectively connected with the output end of the current amplification circuit and the input end of the compensation control circuit, and the output end of the compensation control circuit is connected with one end of the secondary side of the mutual inductor. The embodiment of the application passes through the voltage acquisition circuit acquires the voltage at mutual-inductor secondary side both ends, compensation control circuit control current amplifier circuit produce with the same compensating current of voltage acquisition circuit's output current's wave form, the phase modifier is right compensating current carries out phase adjustment, and passes through compensating current reverse injection after compensating control circuit will adjust extremely the one end of mutual-inductor secondary side can realize the reverse injection of the compensating current of mutual-inductor secondary side on the basis that does not increase auxiliary winding, also can realize simultaneously compensating current aligns with the electromotive force phase place at secondary side both ends to improve the measurement accuracy of mutual-inductor secondary side loop current.
The embodiment of the utility model discloses concrete mutual-inductor secondary side return current detection device, for last embodiment, further explanation and optimization have been made to technical scheme to this embodiment. Specifically, the device for detecting the current of the secondary side loop of the mutual inductor further comprises a controller 07 and a waveform display 08, wherein the input end of the controller 07 is respectively connected with the voltage sampling circuit 04 and the compensation control circuit 06 in the voltage acquisition circuit, and the output end of the controller 07 is connected with the waveform display 08. The controller 7 is preferably a DSP or FPGA with high digital signal processing.
Because the current I output by the output end of the voltage-current conversion circuit 02 after conversion is irrelevant to the load of the output end thereof and is only in direct proportion to the output voltage of the differential amplifier a1, when the output end of the voltage-current conversion circuit 02 is connected with the second resistor Rd (sampling pure resistor), the real-time waveforms of the electromotive force at the two ends of the secondary winding of the mutual inductor can be accurately obtained by measuring the voltage waveforms at the two ends of the second resistor Rd in real time, and the two waveforms have the same phase. The first ADC converts the voltages at the two ends of the second resistor Rd into digital signals, and inputs the digital signals to the controller 07 for processing, and the waveform display 08 displays the voltage waveforms at the two ends of the second resistor Rd in real time (i.e., the voltage difference obtained by subtracting the voltage at the port1 from the voltage at the port 2) by using a uniform time axis.
The compensation control circuit 06 includes a third resistance Rc (sampling pure resistance) and a second ADC for converting a voltage across the third resistance Rc into a digital signal. The current output by the current amplifying circuit 03 sequentially passes through the voltage-current conversion circuit 02, the phase modulator 05, and the third resistor Rc, and then reversely input to one end of the secondary winding through the port 3. The second ADC converts the voltage across the third resistor Rc into a digital signal, inputs the digital signal to the controller 07 for processing, and displays the voltage waveform across the third resistor Rc on the waveform display 08 in real time according to the uniform time axis. Because the waveforms at the two ends of the third resistor Rd and the third resistor Rc are simultaneously displayed on the waveform display 08 according to a uniform time axis, a user can conveniently observe whether the phase relationship between the compensation current generated by the current amplification circuit 03 and the electromotive force at the two ends of the secondary winding meets the phase requirement of the compensation current reverse injection transformer secondary winding when adjusting the phase shifting module. In addition, the ADC can be selected according to actual requirements, but both accuracy and conversion speed need to be taken into consideration. Preferably, the first ADC and the second ADC may be a single-channel, 24-bit ADS7835 manufactured by TI corporation (Texas Instruments).
As shown in fig. 1, the port3 of the reverse injection current is grounded, and the phase adjuster 05 is adjusted according to the voltage waveforms at the two ends of the second resistor Rd and the third resistor Rc displayed simultaneously in the waveform display 08, so that when the phase difference between the waveform at the two ends of the third resistor Rc and the phase difference between the two ends of the second resistor Rd are 180 degrees, the port3 is disconnected from the ground, and the port2 connected to the first resistor R is turned on to implement the reverse injection compensation current. The gain of the current amplification circuit 03 is then adjusted until the voltage difference across the first resistor R is zero (small enough not to be quantized by the first ADC, which can be considered "zero" and sufficiently accurate). When the voltage difference between the two ends of the first resistor R is zero, the compensation current obtained by the second ADC is equal to the secondary side loop current of the transformer.
Therefore, in the embodiment of the application, the controller 07 and the waveform display 08 can display the electromotive force waveforms at the two ends of the secondary winding of the transformer and the waveform of the compensation current reversely injected into the secondary winding of the transformer accurately in real time by using a uniform time axis, so that a user can observe the phase difference between the electromotive force waveforms and the compensation current when adjusting the phase of the compensation current reversely injected into the secondary winding of the transformer, and the phase alignment between the compensation current generated by the adjustable current source and the electromotive force waveforms at the two ends of the secondary winding is realized.
Fig. 2 is a structural diagram of a voltage-current conversion circuit according to the present invention. The voltage-current conversion circuit 02 disclosed in the embodiment of the present application includes a second amplifier a2, a third amplifier A3, a fourth amplifier a4, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, and a ninth resistor R9. The amplifiers a2-a4 may be chopper-stabilized operational amplifiers, wherein the non-inverting input terminal of the second amplifier a2 is connected to the switching voltage Ui through the fourth amplifier a4, the inverting input terminal is connected to the ground through the fifth resistor R5, the output terminal is connected to the non-inverting input terminal of the third amplifier A3, the self-inverting input terminal is connected through the sixth resistor R6, and the non-inverting input terminal of the fourth amplifier a4 is connected through the eighth resistor R8; the output end of the third amplifier A3 is short-circuited with the inverting input end thereof and is connected with the non-inverting input end of the fourth amplifier A4 through the ninth resistor R9; the inverting input terminal of the fourth amplifier a4 is connected to the non-inverting input terminal of the second amplifier a2 through the seventh resistor R7, the output terminal thereof is shorted with the own inverting input terminal thereof, and the non-inverting input terminal thereof serves as an output terminal for converting current. Wherein, R4 ═ R5 ═ R6 ═ R7, R8 ═ R9, can derive according to the amplifier virtual short, virtual break principle: and I is 2Ui/R5 is 2 Ui/R6. Therefore, the output current is only related to the input voltage and the sampling resistor and is not influenced by the load size. The values of the fifth resistor R5 and the sixth resistor R6 in the voltage-current conversion circuit 02 can be set according to actual conditions.
In order to ensure that the current reversely input to one end of the secondary winding can accurately compensate the excitation current, a circuit for measuring the secondary winding loop of the transformer under the condition that the potential difference between the two ends of the first resistor R is zero (namely zero magnetic flux) is realized, and the current amplifying circuit 03 is preferably a current gain/amplification factor adjustable current mirror with accurate current replication and current gain adjustment capability, and the specific circuit is shown in fig. 3.
The current amplifying circuit 03 comprises a first current source Ib1A second current source Ib2A first controllable switch, a second controllable switch, a third controllable switch, a fourth controllable switch, a fifth controllable switch and a gain adjusting resistor RLIn this embodiment, the controllable switch is an NMOS transistor. Correspondingly, NMOS transistor M1Through a first current source Ib1Is connected with a voltage Vdd and a source electrode is connected with an NMOS tube M2Drain electrode, grid electrode and NMOS tube M3The gate of (1) is connected; NMOS tube M2Grid and NMOS tube M4Is connected to the gate of and passes through a second current source Ib2The source electrode of the grounding is grounded; NMOS tube M3The drain electrode of the NMOS transistor is connected with the voltage through the gain adjusting resistor, and the source electrode of the NMOS transistor is connected with the NMOS transistor M4Drain electrode of (1), NMOS tube M4The source of (2) is grounded; NMOS tube M5Grid of the NMOS transistor M1The drain electrode of the transistor is connected with a power supply Vdd, and the source electrode of the transistor is connected with an NMOS tube M2And NMOS transistor M4A gate electrode of (1).
Suppose a first current source Ib1Is sufficiently large, then flows through the NMOS transistor M1Will remain atAnd (6) changing. Therefore, the input current will pass through the NMOS transistor M2Directly to ground, so that the structure has great pull-down current capability. It is noted that the first current source I is fixedb1And a bias voltage VbThe potential at the input point can be kept almost constant. Thus, the input current IinAfter entering the current amplifying circuit 03, the current is transmitted to the output terminal through the current mirror therein, and the gain resistor R outputs a current with a proper valueLAnd converted into a voltage signal. The cascode structure ensures accurate current replication and increases voltage output swing, thereby facilitating variable gain design.
The current amplifying circuit 03 adds an NMOS tube M in the traditional current mirror amplifier5The NMOS tube M5Can isolate the node A from the node B and reduce the NMOS transistor M2The gate and source voltage VGS2 of the NMOS transistor M can be kept high enough1The drain voltage and the source voltage VDS1 and the NMOS tube M2The drain voltage VDS and the source voltage VDS2 not only ensure the output swing of the current amplifying circuit 03, but also improve the current copying precision.
Input current IinWill pass through the NMOS tube M2The variable quantity of the input current can be accurately mirrored to the NMOS transistor M through the cascode current mirror by pulling down to the ground and neglecting non-ideal factors such as body effect, channel length modulation effect and the like4Then through a load resistor RLThe current is converted to a voltage. Therefore, the overall gain of the current amplifying circuit 03 can be expressed as the formula:
wherein, (W/L)4Is an NMOS tube M4Width to length ratio of (W/L)2Is an NMOS tube M2N is the current ratio. gm3Is an NMOS tube M3Transconductance of ro3And ro4Are respectively NMOS tubes M3And NMOS transistor M4The output resistance of (1). It can be seen that the current amplifying circuit 03 not only changes the gain by adjusting the value of the load resistor, but also can change the gainThe circuit gain is adjusted by changing the ratio of the current mirror, and the ratio of the current mirror is easier to accurately design, so that the circuit has great flexibility in designing variable gain. The input current can be scaled up by a current mirror and the resistor R adjustedLThe resistance value of (a) increases the gain of the current mirror amplifier.
Therefore, the current detection device provided by the embodiment of the application can reversely inject the compensation current into one end of the two ends of the secondary winding of the transformer without adding the auxiliary winding, can conveniently and accurately realize the phase alignment of the compensation current generated by the adjustable current source and the electromotive force at the two ends of the secondary winding, and is favorable for realizing the zero electromotive force at the two ends of the secondary winding by regulating the compensation current output by the adjustable current source and reversely injected into the secondary winding of the transformer, namely accurately measuring the secondary side loop current of the transformer under the condition of zero magnetic flux.
It is right above the utility model provides a mutual-inductor secondary side return current detection device has carried out detailed introduction. The embodiments are described in a progressive manner in the specification, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other. The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention.
Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (10)
1. A secondary side loop current detection device of a mutual inductor is characterized by comprising: the device comprises a voltage acquisition circuit, a current amplification circuit, a phase modulator and a compensation control circuit;
the voltage acquisition circuit is connected between two ends of the secondary side of the mutual inductor in series, the input end and the output end of the current amplification circuit are respectively connected with the output end of the voltage acquisition circuit and the input end of the current amplification circuit, the output end of the current amplification circuit is connected with the input end of the phase modulator, the input end and the output end of the phase modulator are respectively connected with the output end of the current amplification circuit and the input end of the compensation control circuit, and the output end of the compensation control circuit is connected with one end of the secondary side of the mutual inductor;
the voltage acquisition circuit is used for acquiring voltages at two ends of a secondary side of the mutual inductor, the current amplification circuit is used for generating compensation current with the same waveform as the output current of the voltage acquisition circuit, the phase modulator is used for carrying out phase adjustment on the compensation current, and the compensation control circuit is used for controlling the current amplification circuit to generate the compensation current with the same waveform as the output current of the voltage acquisition circuit.
2. The transformer secondary side loop current detection device of claim 1, further comprising a controller and a waveform display, wherein:
the input end of the controller is respectively connected with the voltage acquisition circuit and the compensation control circuit, and the output end of the controller is connected with the waveform display.
3. The device for detecting the secondary side loop current of the mutual inductor according to claim 2, wherein the voltage acquisition circuit comprises a voltage measurement circuit, a voltage-current conversion circuit and a voltage sampling circuit, wherein:
the voltage measuring circuit comprises a first amplifier and a first resistor connected to two ends of the first amplifier, the first resistor is connected between two ends of the secondary side of the mutual inductor in series, and one end of the secondary side of the mutual inductor is grounded; the input end of the voltage-current conversion circuit is connected with the output end of the first amplifier; the voltage sampling circuit comprises a second resistor and a first ADC (analog-to-digital converter) used for converting the voltage at two ends of the second resistor into a digital signal, wherein the second resistor is connected between the output end of the voltage-current conversion circuit and the input end of the current amplification circuit in series.
4. The transformer secondary side loop current detection device of claim 3, wherein the compensation control circuit comprises a third resistor and a second ADC for converting a voltage across the third resistor into a digital signal.
5. The device for detecting the secondary side loop current of the mutual inductor as claimed in claim 1, further comprising a voltage-current conversion circuit, wherein an input terminal and an output terminal of the voltage-current conversion circuit are respectively connected to an output terminal of the current amplification circuit and an input terminal of the phase modulator.
6. The transformer secondary side loop current detection device according to claim 3 or 5, wherein the voltage-current conversion circuit includes: the amplifier comprises a first amplifier, a second amplifier, a third amplifier, a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor, an eighth resistor and a ninth resistor, wherein the resistance of the fifth resistor is equal to that of the fourth resistor;
the positive phase input end of the second amplifier is connected with the voltage to be converted through the fourth resistor; the inverting input end of the second amplifier is grounded through the fifth resistor; the output end of the second amplifier is connected with the positive-phase input end of the third amplifier, the self-inverting input end of the second amplifier is connected through the sixth resistor, and the positive-phase input end of the fourth amplifier is connected through the eighth resistor; the output end of the third amplifier is in short circuit with the inverting input end of the third amplifier, and is connected with the non-inverting input end of the fourth amplifier through the ninth resistor; the inverting input end of the fourth amplifier is connected with the non-inverting input end of the second amplifier through the seventh resistor; the output end of the fourth amplifier is in short circuit with the self inverting input end; and the positive phase input end of the fourth amplifier is the output end of the converted current.
7. The secondary side loop current detection device of the mutual inductor according to any one of claims 1 to 5, wherein the current amplification circuit includes: the gain control circuit comprises a first current source, a second current source, a first controllable switch, a second controllable switch, a third controllable switch, a fourth controllable switch, a fifth controllable switch and a gain adjusting resistor;
a first end of the first controllable switch is connected with an input voltage through the first current source, a second end of the first controllable switch is connected with a first end of the second controllable switch, and a control end of the first controllable switch is connected with a control end of the third controllable switch; the control end of the second controllable switch is connected with the control end of the fourth controllable switch and is grounded through the second current source, and the second end of the second controllable switch is grounded; a first end of the third controllable switch is connected with the input voltage through the gain adjusting resistor, a second end of the third controllable switch is connected with a first end of the fourth controllable switch, and a second end of the fourth controllable switch is grounded; the control end of the fifth controllable switch is connected with the first end of the first controllable switch, the first end of the fifth controllable switch is connected with the input voltage, and the second end of the fifth controllable switch is connected with the control ends of the second controllable switch and the fourth controllable switch.
8. The device for detecting the secondary side loop current of the mutual inductor as claimed in claim 7, wherein the current amplifying circuit is a current mirror for adjusting a current gain.
9. The device for detecting the secondary side loop current of the mutual inductor as claimed in claim 3, wherein the first amplifier is an operational amplifier CA3130, and the controller is a DSP processor.
10. The transformer secondary side loop current detection device of claim 4, wherein the first ADC and the second ADC are ADS 7835.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202120723552.0U CN215005588U (en) | 2021-04-09 | 2021-04-09 | Current detection device for secondary side loop of mutual inductor |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202120723552.0U CN215005588U (en) | 2021-04-09 | 2021-04-09 | Current detection device for secondary side loop of mutual inductor |
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| CN215005588U true CN215005588U (en) | 2021-12-03 |
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