CN2641664Y - Automatic test system for zero powder voltage effect of positive temp. coefficient thermistor - Google Patents

Abstract

The utility model discloses a positive temperature coefficient thermister zero energy voltage effect automatic testing system. After being commutated, the output voltage of a program controlling transformer is modulate to form an alternating current half wave impulsion to be charged on a PTCR; a computer performs control to the program controlling transformer, a current gain branch circuit and a voltage gain branch circuit, a data collecting module is divided into two paths to synchronously sample the current gain branch circuit and the voltage gain branch circuit, and the sampling value of the testing voltage and current is obtained to be sent to the computer through an interface module to perform data analysis processing; the computer realizes PTCR temperature increasing and preservation by controlling, collecting and feedback the temperature in an electric furnace through a temperature controlling device; a protective and alarming circuit is arranged in the system. The utility model adopts the alternating current half wave impulsion to replace the short-time direct current impulsion, and the requirement to the switching speed of the high impulsion switch element is less; in addition, the impulsion power is simplified, without a voltage stabilizing capacitor filter of large capacity and high pressure resistance.

Description

Posistor zero power voltage effect Auto-Test System

Technical field

The utility model belongs to the thermistor measuring technology, is specifically related to a kind of PTC thermistor zero power voltage effect Auto-Test System, and it is applicable to the test use of the zero power voltage effect and the zero energy volt-ampere characteristic of posistor (PTCR).

Background technology

The voltage effects of PTCR are meant under External Electrical Field, the phenomenon of crystal boundary potential barrier run-off the straight.Reduce showing as the raising of resistivity of material (referring generally to the measured value more than the Curie point) on the macroscopic view with impressed voltage.Thereby the research voltage effects also are one of important content of research PTC effect.

Carry out at PTCR under the prerequisite of zero energy test, the voltage-current characteristics that records is called the zero energy volt-ampere characteristic.According to this requirement, the test of the zero energy volt-ampere characteristic of PTCR must be strict with and be carried out under zero energy, for this reason, must use the pulse power.The selection of its pulse width should be considered: guarantee to test and carry out under zero energy, and require test to reach certain precision.For the requirement of zero energy, pulse width heals better narrow, but the accuracy requirement pulse width can not be too narrow, can be controlled at about 5ms.Its output impedance of paired pulses power requirement is low, and output amplitude is stable.Particularly for the test before the Curie point, because the sample impedance is low, testing power supply impedance too conference causes bigger test error.

Existing zero energy volt-ampere characteristic method of testing have oscilloscope method and peak value detection method (see Zhou Dongxiang, Pan Xiaoguang. electronic component and testing of materials technology. the 1st edition. Harbin: Heilungkiang science tech publishing house,, 1～73. in 1989).Can see that by Fig. 1 the pulse power that above-mentioned two kinds of methods adopt is and adds pulsed discharge switch composition on the basis of D.C. regulated power supply, specifies as follows:

1. the adjustable pulse power

Transtat becomes required voltage with the alternating current 220V transformation of input.The directly moving voltage of pulse after the rectification becomes direct current through capacitor filtering, uses for pulse switch S.Switch S provides the required pulse voltage that certain power is arranged in the effect of control signal to tested PTCR.Because power work is in pulse condition, and the burst length short (measure for guaranteeing the zero energy resistance, measuring pulsewidth should be less than 5ms).Voltage height, immediate current are big, realize that voltage stabilizing needs jumbo filter capacitor C, so the proving installation volume are big, and price is also high.

2. pulse voltage, current measurement circuit

Pulse voltage, current test method have oscilloscope method and peak value detection method as described above.The oscilloscope method complicated operation, precision is low.Peak value detection method precision height, but have voltage stabilizing difficulty, the high shortcoming of paired pulses power switch requirement.

At present, the zero power voltage effect Auto-Test System device of posistor (PTCR) still belongs to blank at home and abroad.

Summary of the invention

The purpose of this utility model is to provide a kind of posistor zero power voltage effect Auto-Test System, this system simplification the pulse power, saved high capacity, high withstand voltage electric capacity of voltage regulation wave filter, and required much lower the switching speed of high voltage pulse switch device.

A kind of posistor zero power voltage effect Auto-Test System of the present utility model, comprise program control transformer and rectification circuit, it is characterized in that: the output voltage of program control transformer is after the rectification circuit rectification, through pulse-width modulation circuit and synchronizing circuit modulation reshaping, form the alternation pulse and stress on the tested posistor; Computing machine is realized the combined type pressure regulation of program control transformer pair side through control bus gauge tap matrix, forms adjustable voltage; Current gain branch road and voltage gain prop up the route computing machine and realize automatic gear switch by interface module, control bus and switch matrix; Data acquisition module divides above-mentioned voltage gain branch road of two-way synchronized sampling and current gain branch road, obtains the sampled value of test voltage and electric current, and sends into computing machine by interface module and carry out the data analysis processing; Protection, alarm module link to each other with data acquisition module, and send into computing machine by interface module and report to the police; Computing machine is realized the intensification and the insulation of posistor to be measured by the temperature in temperature regulating device control, collection and the feedback electric furnace.

The utility model adopts the alternation pulse to substitute DC pulse in short-term.Because the rising and the decline of alternation pulse change by sinusoidal rule, it is much lower that its instantaneous escalating rate and rate of descent are compared rect.p., so much lower to the switching speed requirement of high voltage pulse switch device; In addition, simplify the pulse power, no longer needed high capacity, high withstand voltage electric capacity of voltage regulation wave filter.Make a concrete analysis of as follows:

According to relevant theoretical, low-repetition-frequency, short-time pulse is measured the estimation of power:

$P_s\≤\frac{\mathrm{\δ}}{1000{\mathrm{\α}}_T}\left(\mathrm{mW}\right)---(1-1)$

In the formula: δ is the dissipation factor (mW/ ℃) of sample, α _TBe temperature coefficient (%/℃), the 1/1000th, the zero power measurement requirement is promptly adopted to cause that change in resistance is no more than 0.1% measurement power.Then V is pressed in pulse test _SFor:

$V_s=\sqrt{P_{s}R}\·\frac{t}{T}---(1-2)$

T is a pulse width in the formula, and T is the cycle, P _sFor measuring power, V _sBe pulse amplitude, R is the sample resistance.Adopt the alternation pulse to replace DC pulse, establishing the DC pulse amplitude is U _m, cycle 2T ₁, peak values of ac U _m, cycle 2T ₂PTCR when energising, its temperature rise be the power that applies to the function of time.DC pulse then:

${\mathrm{<figure-callout\; id="1"\; label="Q"\; filenames="Y0325472200101.png"\; state="\{\{state\}\}">Q</figure-callout>}}_1={\&Integral;}_0^{T_1}\frac{U_m^2}{R\left(t\right)}\mathrm{dt}=\frac{U_m^2}{{\mathrm{<figure-callout\; id="0"\; label="R"\; filenames="Y0325472200101.png"\; state="\{\{state\}\}">R</figure-callout>}}_0}\&CenterDot;T_1---(1-3)$

The alternation pulse:

${\mathrm{<figure-callout\; id="2"\; label="Q"\; filenames="Y0325472200101.png"\; state="\{\{state\}\}">Q</figure-callout>}}_2={\&Integral;}_0^{T_2}\frac{U_m^2}{R\left(t\right)}\sin \mathrm{\&omega;tdt}=\frac{U_m^2}{{\mathrm{<figure-callout\; id="0"\; label="R"\; filenames="Y0325472200101.png"\; state="\{\{state\}\}">R</figure-callout>}}_0}\&CenterDot;\frac{{\mathrm{<figure-callout\; id="2"\; label="T"\; filenames="Y0325472200101.png"\; state="\{\{state\}\}">T</figure-callout>}}_2}{2}---(1-4)$

By Q ₁=Q ₂, T then ₂=2T ₁Above-mentioned showing, applying peak value on the PTCR sample is U _m, 2T ₁The alternation pulse of pulsewidth is equivalent to apply same peak value U _m, pulsewidth T ₁DC pulse.Just based on this, the utility model adopts the alternation pulse to substitute direct current short-time pulse, the voltage effects of testing PTCR.Alternation pulse generation process as shown in Figure 2.

In a word, the utility model proposes and utilize the alternation pulse to substitute conventional direct current short-time pulse, realize the test of PTCR zero energy volt-ampere characteristic.A kind of Auto-Test System is provided simultaneously, can finishes BaTiO automatically ₃The zero power voltage effect of ceramic positive temperature coefficient thermosensitive resistor (PTCR) and the test job of zero energy volt-ampere characteristic.

Description of drawings

Fig. 1 is the proving installation synoptic diagram of existing zero energy volt-ampere characteristic;

Fig. 2 is an alternation pulse generation synoptic diagram of the present utility model;

The structural representation of the test macro that Fig. 3 provides for the utility model;

Fig. 4 is for using the time plot that the utility model system draws;

Fig. 5 is for using resistance-volt curve map that the utility model system draws;

Fig. 6 is for using resistance-warm curve map that the utility model system draws.

Embodiment

As shown in Figure 3, native system adopts unibus control technology, serial a/d device, directly links to each other with upper PC parallel port, realized communication, control integrated.With example the utility model is further described below.

(1) exchanges chamber electricity 220V and divide two-way to insert, divide the power supply of three road direction system circuit boards after one road input rectifying voltage regulating module rectification, the pressure regulation;

(2) program control transformer 2 former sides are inserted on another road, and transformer pair side winding is combined into individual, ten, hundred voltages respectively by 8421 coding rules.After many tap transformer outputs, multitap array mode is adopted in the output of variable voltage.Computing machine OPADD sign indicating number through control bus 4 gauge tap matrixes 3, is realized the pressure regulation of secondary side's combined type, forms adjustable voltage scope 2～600V;

(3) this output voltage (as adopting heavy-duty diode) after rectification circuit 15 rectifications is again by pulse-width modulation circuit 6 and synchronizing circuit 12 modulation reshapings.Pulse-width modulation circuit 6 is made of jointly large power pulse switch IGBT and Drive Protecting Circuit thereof, by control the turning on and off the time of IGBT, comes the alternation width behind the modulation rectification, forms the alternation pulse; Synchronizing circuit 12 is made of every 6N136 jointly shaping circuit 74HC14, phase discriminator 74HC04, light, alternation is carried out synchronous modulation after, form alternation pulse in the accompanying drawing 2.

(4) in the test loop, constitute by alternation pulse, sampling branch road (being divided into current gain branch road 7, voltage gain branch road 8) and PTCR12 to be measured.In the current gain branch road 7, regulate current gain jointly by sample resistance, chip gain PGA103 and branch potential relay; In the voltage gain branch road 8, by divider resistance and the common regulation voltage gain of branch potential relay;

(5) two a sampling route computing machine are realized automatic gear switch by interface module 11, control bus 4, switch matrix 3.Interface module 11 is made of every 6N136 serial ports of computers, parallel port and light; Control bus 4 is made of unibus coding and decoding chip HT12E/D; Switch matrix 3 is constituted according to 8421 coding rules by a plurality of relays;

(6) data acquisition module 9 adopts the above-mentioned voltage gain branch road of two-way serial high-speed a/d-MAX186 synchronized sampling and voltage, the current signal of current gain branch road, obtain the sampled value of test voltage and electric current, and send into computing machine 13 by interface module 11 and carry out the data analysis processing;

(7) protection, alarm module 10 are made of jointly divider resistance, operational amplifier TL081 and adjustable potentiometer, and sampled value and default value are compared.If sampled value surpasses default value, system power supply is cut off in then protection, alarm module 10 actions, and the concurrent alert signal of delivering newspaper is sent into computing machine 13 by interface module 11 and reported to the police.

(8) temperature regulating device of this embodiment is made of temperature control table 14 and platinum resistance 15.Computing machine 13 is by temperature control table control industrial furnace 16, and the temperature by in the platinum resistance 15 sampling industrial furnaces 16 feeds back to temperature control table 14 with sampled value, finishes the communication process with computing machine 13, thereby realizes intensification and the insulation of PTCR17 to be measured.

Above-mentioned test macro model machine functional parameter is as follows:

(1) can finish under the different voltages of posistor (2-600V), in the different temperatures environment (room temperature-300.0 ℃), the automatic test of 8 station sample voltage effects;

(2) this system software is developed based on the popular platform VC6.0 of industry, man-machine interaction, and friendly interface can carry out the setting of online dependence test parameter, can store test result, and numerical value is handled, and shows and printing;

(3) can draw resistance-Wen curve under the different voltages, the resistance under the different temperatures-line of buckling is carried out associated voltage effect CALCULATION OF PARAMETERS, as the voltage effects factor alpha _v

The voltage effects factor alpha _vBe meant: under the certain prerequisite of temperature, the every variation of voltage 1V, the relative change rate of resistance:

${\mathrm{\&alpha;}}_v=\frac{1}{R}\frac{\&PartialD;R}{\&PartialD;U}---(1-6)$

Since in system software operation R-T surface chart, provided the R-T curve under the selected different voltages, so the computing formula of voltage effects coefficient can be changed into:

${\mathrm{\&alpha;}}_v=\frac{1}{R_1}\frac{R_2-R_1}{U_2-U_1}---(1-7)$

R ₁Default value is corresponding Curie temperature T _CResistance value in the time of+50 ℃, different magnitude of voltage (U ₁, U ₂) can import by man-machine conversation.Thereby obtain corresponding R ₂Obtain the voltage effects factor alpha after the calculating _v

The using method of the utility model test macro is:

(1) PTCR to be measured is placed on the anchor clamps, anchor clamps are placed industrial furnace;

(2) check whether electric part connects intact;

(3) open microcomputer, the operation test procedure under the program master menu, is selected hand/automatic measurement pattern.

1) manual measurement pattern

1. set temperature value.

2. wait for that temperature control table control electric furnace is warming up to setting value, and temperature value is stable.

3. set test voltage, channel number, test macro is started working.Finish under the same temperature environment of a paths PTCR zero power voltage effect of several electrical voltage points test in the setting voltage scope.

4. after single channel has been surveyed, can reselect channel number, voltage range, duplicate measurements.

2) automatic measurement pattern.

1. heat up and wait in the design temperature interval;

2. measure automatically, in temperature range, finish the PTCR zero power voltage effect test of each selected in each passage, setting voltage scope electrical voltage point successively; Surveyed, clicked " measure and finish ", closed the rack power supply;

The drafting of (4) three big curves comprises time curve, resistance-volt curve, resistance-warm curve;

(5) graphic printing and numerical analysis are handled;

(6) dispose shutdown.

Accompanying drawing 4 provides the time plot that application system is drawn; Method of testing: 60 ℃ of environment temperatures, during test voltage 300V, to the sample applied voltage test.Be described as follows:

(1) horizontal coordinate in the half-wave test is drawn by relative time (unit is a millisecond);

(2) resistance value is that the voltage and current value of getting certain interval is compared and calculated among the figure.And voltage coordinate adopts (volt) office, and the resistance coordinate adopts (Europe) office, and electric current adopts (peace) office.Mark V-t among the figure successively, R-t, the time curve of I-t.

Accompanying drawing 5 provides resistance-volt curve map that application system is drawn; Method of testing: 200 ℃ of environment temperatures, sample has been carried out continuous applied voltage test, pressurization scope (20～600 volts).2 explanations:

(1) horizontal coordinate is represented test voltage, adopts (volt) office.The resistance that the vertical coordinate representative records, adopt (kilo-ohm) office;

(2) above figure, provided voltage effects coefficient aV1～aV9, (e3) the expression scientific notation: * 10 ^-3, provide environment temperature T value simultaneously.

Accompanying drawing 6 provides resistance-warm curve map that application system is drawn; Method of testing: at ambient temperature range (30 ~ 200 ℃), sample has been carried out continuous applied voltage test, pressurization scope (2～600 volts).2 explanations:

(1) horizontal coordinate is represented environment temperature, adopt (℃) office.The resistance that the vertical coordinate representative records adopts scientific notation, (Europe) office;

(2) above figure, the voltage effects coefficient aV12 of V1-V2 and the voltage effects coefficient aV13 of V1-V3 have been provided, (e3) the expression scientific notation: * 10 ^-3, provide the Curie temperature Tb value of sample simultaneously;

(3) this curve adopts the quadratic function interpolation fitting, and the data distortional point is got rid of.Providing test voltage among the figure successively and be V1 and be 50.0 volts, V2 and be 200.0 volts, V3 is 500.0 volts, and the resistance-warm curve of ambient temperature range (30--200 ℃) obtains the voltage effects comparison diagram under the different condition.

Claims (1)

1, a kind of posistor zero power voltage effect Auto-Test System comprises program control transformer and rectification circuit, it is characterized in that:

The output voltage of program control transformer (2) through pulse-width modulation circuit (6) and synchronizing circuit (12) modulation reshaping, forms the alternation pulse and stresses on the tested posistor (17) after rectification circuit (5) rectification; Computing machine (13) is realized the pressure regulation of the secondary side's combined type of program control transformer (2) through control bus (4) gauge tap matrix (3), forms adjustable voltage;

Current gain branch road (7) and voltage gain branch road (8) are realized automatic gear switch by computing machine (13) by interface module (11), control bus (4) and switch matrix (3);

Data acquisition module (9) divides the two-way synchronized sampling above-mentioned voltage gain branch road (7) and current gain branch road (8), obtains the sampled value of test voltage and electric current, and sends into computing machine (13) by interface module (11) and carry out the data analysis processing;

Protection, alarm module (10) link to each other with data acquisition module (9), and send into computing machine (13) by interface module (11) and report to the police;

Computing machine (13) is realized the intensification and the insulation of posistor to be measured (17) by the temperature in temperature regulating device control, collection and the feedback electric furnace (16).

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