CN102508041A - Method for measuring Delta-type capacitance parameters - Google Patents

Abstract

The invention discloses a method for measuring Delta-type capacitance parameters. In the method, a capacitance tester firstly tests Cab, Cbc and Cca from ab, bc and ca ports outside a Delta-type capacitance network, then obtains a recursive equation according to the Delta-type capacitance network structure, and performs a plurality of iterations to obtain the gradually convergent calculated value until the value meets the precision and error requirements. Through the capacitance tester and an approximation method based on engineering design, the method provided by the invention can obtain a capacitance capacity approximate value satisfying a certain precision requirement. Therefore, the invention provides a rapid and efficient method for test and measurement and the Delta capacitance network tests on a large scale, and meanwhile, the calculation precision can be improved and the complexity can be reduced.

Description

A kind of Delta type capacitance parameter measuring method

Technical field

The invention belongs to the thermometrically technical field, relate in particular to a kind of Delta type capacitance parameter measuring method.

Background technology

Along with the continuous development of production technology, capacitor network more and more is widely used as the components and parts that suppress power supply and electromagnetic interference (EMI).But, still there is not suitable method to how measuring the capacitor volume that has been linked to be the networking.

Delta type capacitance network is the capacitor network that a kind of triangle connects, and is used for filtering and the squelch of three-phase supply etc.Owing to can't open the capacitance that closure is directly measured each limit, can only measure from external connection port, thereby can't obtain the capacity on each limit of triangle capacitor.

Some problem that occurs in the engineering often is difficult to very accurately directly measure and mathematical analysis, and reality also need not obtain strictness and accurate result, because numerical value such as data, variable, coefficient also approximate value just usually itself.Through introducing approximate function, the result of gained gets final product in the error range that allows.

Be new measurement and the computing method of capacitance needs of obtaining the Delta capacitance network that satisfies certain accuracy requirement.

Summary of the invention

To the deficiency that prior art exists, the object of the present invention is to provide a kind of measuring method of Delta type capacitance parameter.The present invention obtains to satisfy the capacitance approximate value of certain accuracy requirement through capacitance measuring tester with based on the approximation method in the engineering design.Thereby be that use screening, the qualification determination that suppresses the components and parts of power supply and electromagnetic interference (EMI) provides a kind of high convenient instrument.For thermometrically and test Delta capacitance network in enormous quantities provide a kind of method rapidly and efficiently, improve estimation precision simultaneously, reduce complexity.

To achieve these goals, the present invention adopts following technical scheme:

A kind of Delta type capacitance network measuring and calculating based on capacitance measuring tester and engineering design approximation method.According to the least significant bit (LSB) of measuring and calculating value and the parameter and the iterations of electric capacity ratings setting approximate equation.Through the several times iteration, the measuring and calculating value restrains gradually, until satisfying precision and error requirements.Concrete steps are following:

1), at first, use capacitance measuring tester to record C from Delta type capacitance network outside ab, bc, ca port respectively _Ab, C _BcAnd C _Ca

2), can draw system of equations (1), (2) according to Delta type capacitance network structure, promptly

$C_{\mathrm{ab}}=C_1+\frac{C_2{C}_3}{C_2+C_3}$ $C_1=C_{\mathrm{ab}}-\frac{C_2{C}_3}{C_2+C_3}$

$C_{\mathrm{bc}}=C_2+\frac{C_1{C}_3}{C_1+C_3}$ $C_2=C_{\mathrm{bc}}-\frac{C_1{C}_3}{C_1+C_3}$

$C_{\mathrm{ca}}=C_3+\frac{C_1{C}_2}{C_1+C_2}$ $C_3=C_{\mathrm{ca}}-\frac{C_1{C}_2}{C_1+C_2}$

System of equations (1) system of equations (2)

Wherein,

C ₁, C ₂, C ₃: the electric capacity that constitutes three electric capacity of Delta type capacitance network

C _Ab, C _Bc, C _Ca: be respectively the electric capacity that the Delta capacitance network is recorded by outside ab, bc and ca port.

3), the recursive algorithm of equation (2) is system of equations (3), that is:

$C_1^{k+1}=C_{\mathrm{ab}}-\frac{C_2^k{C}_3^k}{C_2^k+C_3^k}$

$C_2^{k+1}=C_{\mathrm{bc}}-\frac{C_1^k{C}_3^k}{C_1^k+C_3^k}$

$C_3^{k+1}=C_{\mathrm{ca}}-\frac{C_1^k{C}_2^k}{C_1^k+C_2^k}$

System of equations (3)

Wherein,

(i=1,2,3; K=0; 1; 2......) be the value before the iteration; is the value after the iteration, and initial value

can power taking hold nominal value or its approximate value before the iteration.

is the initial root approximation equation:

$C_1^1=C_{\mathrm{ab}}-\frac{C_2^0{C}_3^0}{C_2^0+C_3^0}$

$C_2^1=C_{\mathrm{bc}}-\frac{C_1^0{C}_3^0}{C_1^0+C_3^0}$

$C_3^1=C_{\mathrm{ca}}-\frac{C_1^0{C}_2^0}{C_1^0+C_2^0}$

Through successive iteration; be convergence gradually between

and

, and error reduces one by one.

convergence gradually between

and

respectively equally, error reduces one by one.In case satisfy pre-conditioned then can stop iteration, generate result, for example (a) iterations, (b) C ₁, C ₂, C ₃Approximate value, (c) C _Ab, C _Bc, C _CaChecking computations value and (d) error amount (with respect to nominal value) etc. can judge whether to do further processing or increase and decrease iterations according to these information.

The present invention has following conspicuous outstanding substantive distinguishing features and remarkable advantage compared with prior art:

A) test of having avoided uncapping.

B) interference and the error of having avoided impedance of earthing earth lead and imperfect earth to cause.

C) can control accuracy.

Description of drawings

Fig. 1 is the process flow diagram of Delta type capacitance network measuring method of the present invention.

Embodiment

Further specify the present invention below in conjunction with accompanying drawing and embodiment.

Embodiment

A kind of Delta type capacitance network measuring and calculating based on capacitance measuring tester and engineering design approximation method.Press the measuring and calculating flow process of Fig. 1.At first, use capacitance measuring tester to record C from ab, bc, ca port respectively _Ab, C _BcAnd C _CaBe respectively 14.817uF, 14.710uF, 14.799uF in this example, with its input equation group 3;

Initial value

can power taking hold nominal value or its approximate value.All be taken as 10uF in this example.

Recursion formula by system of equations (3); After time circulation of different integers, obtain ' measuring and calculating value

data are following:

6 times, $C_1^6=9.90824582335,$ $C_2^6=9.76538519169,$ $C_3^6=9.88435663032;$

10 times, $C_1^{10}=9.90606502467,$ $C_2^{10}=9.76316782809,$ $C_3^{10}=9.88217080566;$

30 times, $C_1^{30}=9.90591874373,$ $C_2^{30}=9.76302140097,$ $C_3^{30}=9.88202450586;$

50 times, $C_1^{50}=9.90591874359,$ $C_2^{50}=9.76302140083,$ $C_3^{50}=9.88202450572;$

Can know the measuring and calculating value by above data:

◆

is roughly to ' 9.90591874359 ' convergence

◆

is roughly to ' 9.76302140083 ' convergence

◆

is roughly to ' 9.88202450572 ' convergence

When cycle index was high more, the measuring and calculating value was accurate more.

According to ' measuring and calculating value

Can checking computations go out C _Ab, C _BcAnd C _Ca6th, 10,30,50 times checking computations value is following:

6 times, C _Ab=14.93215892, C _Bc=14.82518850, C _Ca=14.91414782;

10 times, C _Ab=14.82419869, C _Bc=14.71719866, C _Ca=14.80619872;

30 times, C _Ab=14.81700001, C _Bc=14.71000001, C _Ca=14.79900001;

50 times, C _Ab=14.81700000, C _Bc=14.71000000, C _Ca=14.79900000;

It is thus clear that cycle index is high more, the checking computations value is more near measured value C _Ab, C _BcAnd C _CaThrough increasing continuously iterations, the measuring and calculating value restrains gradually, until satisfying precision and error requirements.According to (a) iteration (circulation) number of times, (b) measuring and calculating value, (c) checking computations value and (d) error etc., judge whether to continue iteration.For measuring and calculating in batches, can obtain required iterations according to first sample measuring and calculating.

Claims (3)

1. Delta type capacitance parameter measuring method, step is following:

1), at first, use capacitance measuring tester to record C from Delta type capacitance network outside ab, bc, ca port respectively _Ab, C _BcAnd C _Ca

2), can draw system of equations (1), (2) according to Delta type capacitance network structure, promptly

$C_{\mathrm{ab}}=C_1+\frac{C_2{C}_3}{C_2+C_3}$ $C_1=C_{\mathrm{ab}}-\frac{C_2{C}_3}{C_2+C_3}$

$C_{\mathrm{bc}}=C_2+\frac{C_1{C}_3}{C_1+C_3}$ $C_2=C_{\mathrm{bc}}-\frac{C_1{C}_3}{C_1+C_3}$

$C_{\mathrm{ca}}=C_3+\frac{C_1{C}_2}{C_1+C_2}$ $C_3=C_{\mathrm{ca}}-\frac{C_1{C}_2}{C_1+C_2}$

System of equations (1) system of equations (2)

Wherein, C ₁, C ₂, C ₃It is the electric capacity that constitutes three electric capacity of Delta type capacitance network;

3), the stepping type of equation (2) is system of equations (3), that is:

$C_1^{k+1}=C_{\mathrm{ab}}-\frac{C_2^k{C}_3^k}{C_2^k+C_3^k}$

$C_2^{k+1}=C_{\mathrm{bc}}-\frac{C_1^k{C}_3^k}{C_1^k+C_3^k}$

$C_3^{k+1}=C_{\mathrm{ca}}-\frac{C_1^k{C}_2^k}{C_1^k+C_2^k}$

System of equations (3)

Wherein,

(i=1; 2,3; K=0; 1; 2......) be the value before the iteration;

is the value after the iteration; Through successive iteration;

be convergence gradually between

and

; Error reduces one by one; In like manner;

convergence gradually between

and

respectively; Error reduces one by one; Satisfy and stop iteration after pre-conditioned, obtain the result.

2. a kind of Delta type capacitance parameter measuring method according to claim 1; It is characterized in that: nominal value or its approximate value are held in initial value

power taking before the said iteration, and

is the first approximate value of equattion root.

3. Delta type capacitance parameter measuring method according to claim 1 is characterized in that: the significance bit that the precision of the capacitance parameter that measuring and calculating obtains and the uncertainty that surveying instrument is depended in accuracy or error and computation process keep.

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