CN111781469A - Phase difference-free Rogowski coil for measuring discharge current of pulse plasma thruster - Google Patents
Phase difference-free Rogowski coil for measuring discharge current of pulse plasma thruster Download PDFInfo
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- CN111781469A CN111781469A CN202010423301.0A CN202010423301A CN111781469A CN 111781469 A CN111781469 A CN 111781469A CN 202010423301 A CN202010423301 A CN 202010423301A CN 111781469 A CN111781469 A CN 111781469A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/12—Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing
- G01R31/1227—Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing of components, parts or materials
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F5/00—Coils
- H01F5/06—Insulation of windings
Abstract
The invention provides a phase difference-free Rogowski coil for measuring discharge current of a pulse plasma thruster. The method adopts a non-contact mode to realize the measurement of the pulse current generated by the discharge of the thruster in vacuum. The measurement object is the discharge current of the pulse plasma thruster in the field of electric propulsion. The main structure of the measuring system comprises: a turn coil, a bobbin, and an outer integrator. The invention can obtain the direct proportional relation between the integrated induced electromotive force and the passing pulse discharge current according to the Faraday's law of electromagnetic induction and the matching loop law by measuring the electromagnetic induced electromotive force passing through two ends of the winding coil and integrating through the analog circuit. And finally, calibrating through an internally connected current measuring element, thereby realizing the measurement of the non-contact pulse current.
Description
Technical Field
The invention belongs to the field of electric propulsion plasma diagnosis, and particularly relates to a phase difference-free Rogowski coil for measuring discharge current of a pulse plasma thruster by using a non-contact method.
Background
The pulse plasma thruster is an advanced propulsion mode which utilizes a propellant directly ionized by pulse discharge to accelerate charged particles to be sprayed out through an electromagnetic field so as to obtain propulsion power. Compared with the traditional chemical propulsion mode, the propulsion of the pulse plasma thruster has the remarkable advantages that: high specific impulse and high efficiency, and has wide application prospect in space tasks of large-scale spacecraft, such as orbit control, deep space exploration, interstellar navigation and the like. The pulsed plasma thruster is widely applied to a main propulsion system of a satellite and a deep space probe at present.
The measurement of basic discharge characteristics of the pulsed plasma thruster, such as discharge voltage, discharge current and other related parameters, is of great significance for improving and optimizing engine design and engine performance. The discharge current of the electric thruster directly determines the size and the efficiency of the specific impulse of the engine, and is the most basic and important parameter for detecting the working state of the thruster. Therefore, measuring the discharge current of the pulsed plasma thruster is a crucial loop in plasma diagnosis of the electric thruster. However, the discharge of the pulsed plasma thruster is capacitive instantaneous discharge, the working condition of vacuum, the discharge current is in the kA level, the time is in the μ s level, and noise generated by a spark plug is generated before the discharge is triggered, which brings great challenges to the measurement of the discharge current. For the large current generated by the pulse discharge of the pulse plasma thruster, no special diagnosis method is available for measurement at present.
Disclosure of Invention
The invention aims to provide a phase difference-free Rogowski coil for measuring the discharge current of a pulse plasma thruster, which can measure and obtain a discharge characteristic curve of the discharge current of an engine and finally realize the non-contact measurement of the discharge current of the pulse plasma thruster in vacuum. The specific contents are as follows:
a phase difference-free Rogowski coil for measuring a discharge current of a pulsed plasma thruster specifically comprises: a turn coil and a bobbin. The turn-winding coil is densely wound into 400 turns by an enameled wire and wound on the coil frame in a ring shape; the coil rack is made of copper-money-shaped epoxy resin material with a circular through hole in the middle, and the circular through hole is used for penetrating through a capacitor anode of the thruster; the outside of the coil former is sealed with epoxy glue.
Furthermore, the coil rack leads out the positive and negative poles of the two winding wires.
The measuring system for measuring the discharge current of the pulsed plasma thruster based on the Rogowski coil comprises: rogowski coil and external circuit. The external circuit comprises an external integral circuit resistor and a capacitor.
Further, the external integral circuit is: sampling resistor R1Connected in parallel with the Rogowski coil; integral resistor R2And a sampling resistor R1The positive electrodes are electrically connected; u. ofi(t) is mutual electromotive force of the Rogowski coil without an integrator along with the discharge current i (t); integrating capacitor C and integrating resistor R2Is electrically connected with the positive electrode of the integrating capacitor, and the other end of the integrating capacitor is connected with the sampling resistor R1The negative electrodes of the two electrodes are electrically connected; filter resistor R3With integrating capacitor C and integrating resistor R2The public terminal of the network is electrically connected; wherein L is the self-inductance of the Rogowski coil, r is the DC resistance of the Rogowski coil, C0Is a parasitic capacitance.
The method for measuring the discharge current of the pulse plasma thruster based on the phase-difference-free Rogowski coil comprises the following steps of:
(1) sleeving the Rogowski coil on a lead through which the discharge current flows, so that the discharge current passes through the right center of the Rogowski coil; the two ends of the wire on the Rogowski coil correspondingly generate variable electromotive force.
(2) Deducing integral value u of electromotive force generated by wire on Rogowski coilcAnd a mathematical relationship with the pulsed plasma thruster discharge current i (t) through the coil.
When the pulse current passes through the center of the Rogowski coil, the closely wound conducting wire on the Rogowski coil generates a variable current, and the formula (1) is derived according to the ampere loop theorem:
obtaining u from formula (1)iThe integral value of the voltage is in direct proportion to the discharge current i (t) of the thruster passing through the center of the rogowski coil, and the voltage value generated by the current flowing through the resistor and the inductor in the measuring loop is always equal to the mutual induction voltage u of the rogowski coiliTo give formula (2):
wherein: n is the number of turns of Rogowski coil, M is the mutual inductance of Rogowski coil, B is the magnetic induction intensity, S is the integral loop of Rogowski coil, t is time, L is the self-inductance of Rogowski coil, C0As a parasitic capacitance, u1For integrating the voltage across the circuit, R is the DC resistance of the Rogowski coil, R1Is a sampling resistor.
(3) Calculating induced electromotive force u of integral external circuit1。
(4) Calculating a transfer function H of the Rogowski coil measuring system; establishing sensitivity and system characteristics of Rogowski coil system H(s) and integral resistance R2And the capacitance C.
Under the condition that the initial condition is 0, according to Laplace transformation, an electromotive force equation (1) is induced at two ends of the Rogowski coil, a voltage and current equation (2) of a measuring loop and an integral equation (3) of a circuit outside the Rogowski coil, and transfer functions of the three equations are respectively:
for the series circuit of the rogowski coil with the measurement circuit and the integration circuit, the overall transfer function h(s) is the product of equations (4), (5), (6):
(5) obtaining the resistance R of the integrating circuit according to model calculation2And obtaining a calibration coefficient without time phase difference by taking values of reasonable parameters of the capacitor C.
(6) And (5) obtaining a standard value of the current by adopting a measuring method of the circuit internal connection shunt through the calibration coefficient in the step (5), and obtaining a measured value of the Rogowski coil for measuring the discharge current.
Compared with the prior art, the invention has the following beneficial effects:
(1) the invention realizes the measurement of the discharge current of the pulse plasma thruster on the basis of the Faraday law of electromagnetic induction and the ampere loop law, the direct proportional relation between the electromotive force integral value of the Rogowski coil and the passing current value and the integration mode of a resistor and capacitor (RC integrator) analog circuit.
(2) The Rogowski coil is sealed by adopting the epoxy resin material. On one hand, the insulativity inside the Rogowski coil is ensured; on the other hand, the coil can be used in vacuum.
(3) The Rogowski coil is calibrated by taking the shunt connected in the discharge circuit as a standard value, so that the absolute accuracy of a measured value is guaranteed, and the non-contact accurate measurement of the pulse current of the Rogowski coil is realized.
(4) The invention derives the transfer function of the Rogowski coil measuring system, firstly proposes the constant correlation between the sensitivity and the phase of the Rogowski coil system and the time of the integrating circuit, and realizes the Rogowski coil measuring system without phase error.
Drawings
Fig. 1 is a two-dimensional cross-sectional view of a rogowski coil of the present invention.
Fig. 2 is a schematic diagram of a connection mode between the rogowski coil and an external circuit according to the present invention.
Fig. 3 is a schematic diagram of an external circuit of the rogowski coil of the present invention.
Wherein i (t) -pulsed plasma thruster discharge current of coil, R1Sampling resistance, R2Integral resistance, R3-a filter resistance, C-an integrating capacitance; self-inductance of the L-coil, direct-current resistance of the r-coil, C0Parasitic capacitance, U0-a Rogowski coil induced electromotive force, Uc-integrating the induced electromotive force.
Detailed Description
The invention will be described in more detail with reference to the following figures and examples, but the scope of the invention is not limited thereto.
The invention aims to design a Rogowski coil for measuring the discharge current of a pulse plasma thruster so as to measure the discharge characteristic curve of the discharge current of an engine. The rogowski coil for measuring the discharge current of the pulse plasma thruster specifically comprises: a turn coil and a bobbin. The winding coil is densely wound into 400 turns by using an enameled wire and wound on a neutral polytetrafluoroethylene ring in a ring shape, and the wound ring coil needs to be wound around a coil frame for one circle and is led out of a positive wire and a negative wire; the coil rack is made of copper-money-shaped epoxy resin material with a circular through hole in the middle, and the circular through hole is used for penetrating through a capacitor anode of the thruster, so that the discharge current completely penetrates through the Rogowski coil in the discharge process; the outside of the coil rack is sealed by epoxy resin glue, so that the insulativity inside the Rogowski coil is ensured on one hand, and the coil can be used in vacuum on the other hand; the coil portion of the rogowski coil (as shown in fig. 1) has been described to perform its function primarily to generate an induced electromotive force on the winding wire by passing a pulse current through the central hole of the bobbin.
The external integrator circuit diagram (shown in fig. 3) of the rogowski coil provided by the invention comprises an analog circuit formed by a resistor and a capacitor. Wherein R is1For sampling resistors also called damping resistors, R2As integrating resistance, R3Is a filter resistor, C is an integrating capacitor, L is the self-inductance coefficient of the Rogowski coil, and r is the inductance of the Rogowski coilFlow resistance, C0Is a parasitic capacitance. The method comprises the following specific steps:
(1) sleeving the Rogowski coil on a lead through which the discharge current flows, so that the discharge current passes through the right center of the Rogowski coil; the two ends of the wire on the Rogowski coil correspondingly generate variable electromotive force;
deducing integral value u of electromotive force generated by wire on Rogowski coilcA mathematical relationship with the pulsed plasma thruster discharge current i (t) through the coil;
when the pulse current passes through the center of the Rogowski coil, the closely wound conducting wire on the Rogowski coil generates a variable current, and the formula (1) is derived according to the ampere loop theorem:
obtaining u from formula (1)iThe integral value of the voltage is in direct proportion to the discharge current i (t) of the thruster passing through the center of the rogowski coil, and the voltage value generated by the current flowing through the resistor and the inductor in the measuring loop is always equal to the mutual induction voltage u of the rogowski coiliTo give formula (2):
wherein: n is the number of turns of Rogowski coil, M is the mutual inductance of Rogowski coil, B is the magnetic induction intensity, S is the integral loop of Rogowski coil, t is time, L is the self-inductance of Rogowski coil, C0As a parasitic capacitance, u1For integrating the voltage across the circuit, R is the DC resistance of the Rogowski coil, R1Is a sampling resistor;
(3) calculating induced electromotive force u of integral external circuit1：
(4) Calculating a transfer function H of the Rogowski coil measuring system; establishing sensitivity and system characteristics of Rogowski coil system H(s) and integral resistance R2And a capacitorThe relationship of C;
under the condition that the initial condition is 0, according to Laplace transformation, an electromotive force equation (1) is induced at two ends of the Rogowski coil, a voltage current equation (2) of a measuring loop and an integral equation (3) of a circuit outside the Rogowski coil, and transfer functions of the three equations are respectively:
for the series circuit of the rogowski coil with the measurement circuit and the integration circuit, the overall transfer function h(s) is the product of equations (4), (5), (6):
(5) obtaining the resistance R of the integrating circuit according to model calculation2And the reasonable parameter value of the capacitor C to obtain a calibration coefficient without time phase difference;
(6) and (5) obtaining a standard value of the current by adopting a measuring method of the circuit internal connection shunt through the calibration coefficient in the step (5), and obtaining a measured value of the Rogowski coil for measuring the discharge current.
In the actual measurement process, the parameters of the integrating circuit need to be further adjusted and set through experiments. Pulse plasma thruster discharge current i (t) of coil and mutual electromotive force u of Rogowski coiliThe integral value of (t) is proportional, and a small phase difference relationship exists under the influence of the parameters of the integral circuit. The pulse current measuring device and the pulse current measuring method are used for finally completing the measurement of the pulse current through an external integration circuit in the Rogowski coil measuring process.
Although exemplary embodiments of the present invention have been described for illustrative purposes, those skilled in the art will appreciate that various modifications, additions, substitutions and the like can be made in form and detail without departing from the scope and spirit of the invention as disclosed in the accompanying claims, all of which are intended to fall within the scope of the claims, and that various steps in the various sections and methods of the claimed product can be combined together in any combination. Therefore, the description of the embodiments disclosed in the present invention is not intended to limit the scope of the present invention, but to describe the present invention. Accordingly, the scope of the present invention is not limited by the above embodiments, but is defined by the claims or their equivalents.
Claims (5)
1. A phase difference-free Rogowski coil for measuring a discharge current of a pulsed plasma thruster is characterized by specifically comprising: a turn coil and a bobbin; the turn-winding coil is densely wound into 400 turns by an enameled wire and wound on the coil frame in a ring shape; the coil rack is made of copper-money-shaped epoxy resin material with a circular through hole in the middle, and the circular through hole is used for penetrating through a capacitor anode of the thruster; the outside of the coil former is sealed with epoxy glue.
2. The rogowski coil of claim 1, wherein the coil former draws positive and negative poles of two winding turns.
3. A measuring system for measuring a discharge current of a pulsed plasma thruster based on the rogowski coil of claim 1, comprising: the Rogowski coil and the external circuit; the external circuit comprises an external integral circuit resistor and a capacitor.
4. The measurement system of claim 3, wherein the external integration circuit is: sampling resistor R1Connected in parallel with the Rogowski coil; integral resistor R2And a sampling resistor R1The positive electrodes are electrically connected; u. ofi(t) is mutual electromotive force of the Rogowski coil without an integrator along with the discharge current i (t); integrating capacitor C and integrating resistor R2Is electrically connected to the positive electrode ofThe other end of the branch capacitor C and the sampling resistor R1The negative electrodes of the two electrodes are electrically connected; filter resistor R3With integrating capacitor C and integrating resistor R2The public terminal of the network is electrically connected; wherein L is the self-inductance of the Rogowski coil, r is the DC resistance of the Rogowski coil, C0Is a parasitic capacitance.
5. The method for measuring the discharge current of the pulsed plasma thruster based on the phase-difference-free rogowski coil of claim 4, is characterized by comprising the following steps of:
(1) sleeving the Rogowski coil on a lead through which the discharge current flows, so that the discharge current passes through the right center of the Rogowski coil; the two ends of the wire on the Rogowski coil correspondingly generate variable electromotive force;
(2) deducing integral value u of electromotive force generated by wire on Rogowski coilcA mathematical relationship with the pulsed plasma thruster discharge current i (t) through the coil;
when the pulse current passes through the center of the Rogowski coil, the closely wound conducting wire on the Rogowski coil generates a variable current, and the formula (1) is derived according to the ampere loop theorem:
obtaining u from formula (1)iThe integral value of the voltage is in direct proportion to the discharge current i (t) of the thruster passing through the center of the rogowski coil, and the voltage value generated by the current flowing through the resistor and the inductor in the measuring loop is always equal to the mutual induction voltage u of the rogowski coiliTo give formula (2):
wherein: n is the number of turns of Rogowski coil, M is the mutual inductance of Rogowski coil, B is the magnetic induction intensity, S is the integral loop of Rogowski coil, t is time, L is the self-inductance of Rogowski coil, C0As a parasitic capacitance, u1For integrating the voltage across the circuit, R is the DC resistance of the Rogowski coil, R1Is a sampling resistor;
(3) calculating induced electromotive force u of integral external circuit1：
(4) Calculating a transfer function H of the Rogowski coil measuring system; establishing sensitivity and system characteristics of Rogowski coil system H(s) and integral resistance R2And capacitance C;
under the condition that the initial condition is 0, according to Laplace transformation, an electromotive force equation (1) is induced at two ends of the Rogowski coil, a voltage and current equation (2) of a measuring loop and an integral equation (3) of a circuit outside the Rogowski coil, and transfer functions of the three equations are respectively:
for the series circuit of the rogowski coil with the measurement circuit and the integration circuit, the overall transfer function h(s) is the product of equations (4), (5), (6):
(5) obtaining the resistance R of the integrating circuit according to model calculation2And the reasonable parameter value of the capacitor C to obtain a calibration coefficient without time phase difference;
(6) and (5) obtaining a standard value of the current by adopting a measuring method of the circuit internal connection shunt through the calibration coefficient in the step (5), and obtaining a measured value of the Rogowski coil for measuring the discharge current.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114638193A (en) * | 2022-01-25 | 2022-06-17 | 宁波力斗智能技术有限公司 | Lumped parameter-based bandwidth rapid calculation method for flexible Rogowski coil current sensor |
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| CN104407192A (en) * | 2014-11-26 | 2015-03-11 | 国家电网公司 | Openable Rogowski coil assembly for measuring lightning current in power transmission line |
| DE102016109276A1 (en) * | 2016-05-20 | 2017-11-23 | Dr. Ing. H.C. F. Porsche Aktiengesellschaft | Measuring device and measuring method for measuring an electric current with a Rogowski coil |
| CN108414812A (en) * | 2018-02-06 | 2018-08-17 | 国网安徽省电力有限公司 | A kind of electronic current mutual inductor and its characteristic analysis method based on Rogowski coil |
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2020
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Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN201910325U (en) * | 2010-11-29 | 2011-07-27 | 浙江工业大学 | Active photoelectric type current transformer based on digital signal processor (DSP) |
| CN102968519A (en) * | 2012-10-15 | 2013-03-13 | 广东电网公司电力科学研究院 | Model of electronic current transformer with hollow coil in electrical system and modeling method thereof |
| CN203084044U (en) * | 2013-01-09 | 2013-07-24 | 武汉三相电力科技有限公司 | Self-integrating Rogowski coil capable of low frequency characteristic correction |
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| CN104407192A (en) * | 2014-11-26 | 2015-03-11 | 国家电网公司 | Openable Rogowski coil assembly for measuring lightning current in power transmission line |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN114638193A (en) * | 2022-01-25 | 2022-06-17 | 宁波力斗智能技术有限公司 | Lumped parameter-based bandwidth rapid calculation method for flexible Rogowski coil current sensor |
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