CN105510825A - Asynchronous motor leakage inductance measurement method for eliminating non-linear factor - Google Patents

Abstract

The invention relates to an asynchronous motor leakage inductance measurement method for eliminating a non-linear factor. A measurement loop is loaded on a three-phase circuit of a three-phase asynchronous motor and comprises three groups of testing loops connected in parallel; and each testing loop includes two IGBTs connected in series. Each circuit of the three-phase circuit is connected with one testing loop group in one-to-one correspondence mode; a connection point is located at the line between each two IGBTs; and a diode is installed on each IBGT in a conducting mode and is used for carrying out sampling on each circuit. A direct-current power supply provides power for the testing loop; and according to current data by sampling of each circuit, calculation is carried out to obtain a motor stator resistance value. According to the invention, with the method, no influence on the testing result by the IGBT dead zone blocking time is caused and the influences of the non-linear links like the eddy current effect and the skin effect is also taken into consideration. And on the basis of the numerical analysis, the influence caused by the measurement error can be reduced, thereby obtaining a precise leakage inductance measurement value.

Description

A kind of asynchronous machine leakage inductance measuring method eliminating non-linear factor

Technical field

The invention belongs to electric-power metering detection field, particularly a kind of asynchronous machine leakage inductance measuring method eliminating non-linear factor.

Background technology

The control performance of asynchronous motor speed-regulating system largely depends on the acquisition of the accurate parameter of electric machine, and in numerous applications, the parameter of motor is ignorant in advance, a lot of scholar proposes the different modes that leakage reactance is measured, but the error problem that still existence is more or less certain in the application of reality.

(test mode being selected from " Proceedings of the CSEE " 06 phase in 2012 is on of ac superposition direct current thus the impact in minimizing dead band to document " the static parameter identification method of the asynchronous machine based on adaptive equalization ", but does not consider the nonlinear influencing factors such as eddy current.

Document " Parameteridentificationofaninductionmachineatstandstillu singthevectorconstructingmethod " (" IEEETransactionsonPowerElectronics ", 2012,27 (2): 905-915DOI:10.1109/TPEL.2010.2089699) vectorial structured approach is adopted to measure the parameter of electric machine, although this method obtains good measurement effect, have ignored the impact of dead band on measuring accuracy.This patent proposes a kind of method that leakage reactance is measured, and can calculate leakage reactance more accurately, avoid the impact that nonlinear element and IGBT dead band blocking time produce, and above-mentioned document has obvious difference.

Summary of the invention

The object of the invention is for the deficiencies in the prior art, propose a kind of calculating leakage reactance more accurately and effective asynchronous machine leakage inductance measuring method eliminating non-linear factor.

The present invention solves its technical matters and takes following technical scheme to realize:

Eliminate an asynchronous machine leakage inductance measuring method for non-linear factor, the measuring circuit in this measuring method is by stator resistance R _s, motor leakage inductance L _σ', motor excitation inductance L _m' connect and powered by inverter output end, inverter outgoing side voltage is expressed as u _s, at motor excitation mutual inductance L _mtwo ends are parallel with rotor resistance R _r, stator resistance R _sproduce stator current i _s, produce motor excitation impedance two ends induced potential w ψ ' at motor excitation inductance two ends, when us impact, due to L _m' > > L _σ', ignore L _m' on the electric current that flows through, have following formula to set up:

$u_s=i_s*(R_s+R_r)+{L_{\mathrm{\σ}}}^{\′}*\frac{{\mathrm{di}}_s}{dt}$

L _σ' metering system be: measuring circuit is carried on the three-phase circuit of threephase asynchronous machine, this test loop comprises the test circuit of three groups of parallel connections, often organize the IGBT that test circuit comprises two series connection, every circuit of three-phase circuit respectively respective one_to_one corresponding is connected with wherein one group of test circuit, on the circuit of tie point between two IGBT, on each IGBT, equal conducting is provided with a diode, for sampling to every circuit, test circuit is by DC power supply, according to the current data to every circuit sampling, by calculating motor stator resistance value, testing procedure is:

Make pipe conducting on A phase brachium pontis, B pipe conducting under C phase brachium pontis, voltage u _dcbe added on A-BC end, as stator current i _areach the peak value i of rated current ₂time, record current time t ₂, then under making pipe on A phase brachium pontis turn off, pipe conducting allows electric current by D4 diode continuousing flow.

When current attenuation is to i ₃=i ₂* e ^-1time, record now moment t ₃, and make B under C phase brachium pontis pipe turn off upper pipe conducting, allow voltage _ u _dcbe added on u _a-BCend.

Work as i _aarrive reverse rated current peak value, record now moment t ₄, and under again making A phase brachium pontis, the upper pipe conducting of pipe shutoff allows electric current by D1 diode continuousing flow.

At t ₅=t ₄+ Δ t record current i ₅, at t ₆=t ₅+ Δ t record current i ₆, wherein Δ t=ln2 × (t ₃-t ₂)

Finally obtain: $L_{\mathrm{\σ}}=-\frac{2u_{dc}}{3}*\frac{t_3-t_4}{i_3-\frac{{i_5}^2}{i_6}}.$

Advantage of the present invention and good effect are:

The asynchronous machine leakage inductance measuring method of elimination non-linear factor provided by the invention can make IGBT dead band blocking time not have an impact to test result, and consider the impact of the nonlinear element such as eddy effect, kelvin effect generation, pass through numerical analysis, reduce the impact that measuring error is brought, thus obtain more accurate leakage inductance measured value.

Accompanying drawing explanation

Fig. 1 is the T-shaped figure of equivalence of testing of electric motors of the present invention;

Fig. 2 is the topological diagram of metering circuit of the present invention;

Fig. 3 is leakage inductance measuring principle figure of the present invention;

Fig. 4 is kelvin effect schematic diagram involved in embodiment.

Embodiment

Be further described the invention process below in conjunction with accompanying drawing, following examples are descriptive, are not determinate, can not limit protection scope of the present invention with this.

Eliminate an asynchronous machine leakage inductance measuring method for non-linear factor, see that the measuring circuit in this measuring method of Fig. 1 is by stator resistance R _s, motor leakage inductance L _σ', motor excitation inductance L _m' connect and powered by inverter output end, inverter outgoing side voltage is expressed as u _s, at motor excitation mutual inductance L _mtwo ends are parallel with rotor resistance R _r, stator resistance R _sproduce stator current i _s, produce motor excitation impedance two ends induced potential w ψ ' at motor excitation inductance two ends, when us impact, due to L _m' > > L _σ', ignore L _m' on the electric current that flows through, have following formula to set up:

$u_s=i_s*(R_s+R_r)+{L_{\mathrm{\σ}}}^{\′}*\frac{{\mathrm{di}}_s}{dt},$

L _σ' metering system be: see that measuring circuit is carried on the three-phase circuit of threephase asynchronous machine by Fig. 2 ~ Fig. 3, this test loop comprises the test circuit of three groups of parallel connections, often organize the IGBT that test circuit comprises two series connection, every circuit of three-phase circuit respectively respective one_to_one corresponding is connected with wherein one group of test circuit, on the circuit of tie point between two IGBT, on each IGBT, equal conducting is provided with a diode, for sampling to every circuit, test circuit is by DC power supply, according to the current data to every circuit sampling, by calculating motor stator resistance value, testing procedure is:

Make pipe conducting on A phase brachium pontis, B pipe conducting under C phase brachium pontis, voltage u _dcbe added on A-BC end, as stator current i _areach the peak value i of rated current ₂time, record current time t ₂, then under making pipe on A phase brachium pontis turn off, pipe conducting allows electric current by D4 diode continuousing flow.

When current attenuation is to i ₃=i ₂* e ^-1time, record now moment t ₃, and make B under C phase brachium pontis pipe turn off upper pipe conducting, allow voltage _ u _dcbe added on u _a-BCend.

Work as i _aarrive reverse rated current peak value, record now moment t ₄, and under again making A phase brachium pontis, the upper pipe conducting of pipe shutoff allows electric current by D1 diode continuousing flow.

At t ₅=t ₄+ Δ t record current i ₅, at t ₆=t ₅+ Δ t record current i ₆, wherein Δ t=ln2 × (t ₃-t ₂)

Finally obtain: $L_{\mathrm{\σ}}=-\frac{2u_{dc}}{3}*\frac{t_3-t_4}{i_3-\frac{{i_5}^2}{i_6}}$

Why use t ₃-t ₄the current differential in moment calculates leakage inductance, is because it compares t ₁-t ₂the more advantage of Shi Keyou.T on the one hand ₃-t ₄the differential electrical flow valuve in moment and Differential time compare t ₁-t ₂moment numerical value is larger, and the leakage inductance calculated like this is more accurate.Be in this section of process on the other hand, IGBT dead band blocking time can not have impact to this test result.Because at t ₃in moment closedown A phase during pipe, due to current i _a>0, immediately from the diode continuousing flow of A phase bottom, thus can be equivalent to the switching that A phase completes on off state immediately.B, C phase commutation process in like manner.

Because the existence of eddy effect and kelvin effect in reality, directly use current i ₄the leakage inductance calculated, can be less than normal compared with leakage inductance during motor actual motion.

As shown in Figure 4, on the one hand because motor gullet base interlinked leakage is more than top, therefore bottom reactance is larger.When electric current Rapid Variable Design, impedance determines primarily of reactance, and kelvin effect makes distribution of current reduce gradually from top to bottom, can than less during balanced current distribution by the interlinked leakage of iron core.The voltage u in leakage inductance is carried on the other hand due to the method _dccomparatively large, electric current can rise rapidly, thus produces leakage flux ψ fast _o, and leakage flux change fast can cause iron core place to induce electromotive force, the eddy current that electromotive force produces has magnetic flux ψ _i, and then oppositely weakening is produced to its magnetic field, this effect can make synthesis leakage flux ψ=ψ _o-ψ _i< ψ _o.The inductance that above factor causes using the galvanometer at t4 place to calculate can less than normal than in actual motion.

Due at i _aduring decay, the impact of eddy effect and kelvin effect is very little, therefore in order to avoid the impact that this effect is brought, uses i _{4 ＇}replace i ₄, its value is according to t ₅-t ₆the time interval be back-calculated to obtain according to exponent arithmetic, if t ₄-t ₆the time interval gets Δ t, then have

$i_5=i_{4^{\&prime;}}*e^{-\frac{\mathrm{\&Delta;}t}{\mathrm{\&tau;}}}$

$i_6=i_{4^{\&prime;}}*e^{-\frac{2\mathrm{\&Delta;}t}{\mathrm{\&tau;}}}$

Above simultaneous, two formulas obtain $i_{4^{\&prime;}}=\frac{{i_5}^2}{i_6}.$

Although disclose embodiments of the invention and accompanying drawing for the purpose of illustration, but it will be appreciated by those skilled in the art that: in the spirit and scope not departing from the present invention and claims, various replacement, change and amendment are all possible, therefore, scope of the present invention is not limited to the content disclosed in embodiment and accompanying drawing.

Claims (1)

1. eliminate an asynchronous machine leakage inductance measuring method for non-linear factor, it is characterized in that: the measuring circuit in this measuring method is by stator resistance R _s, motor leakage inductance L _σ', motor excitation inductance L _m' connect and powered by inverter output end, inverter outgoing side voltage is expressed as u _s, at motor excitation mutual inductance L _mtwo ends are parallel with rotor resistance R _r, stator resistance R _sproduce stator current i _s, produce motor excitation impedance two ends induced potential w ψ ' at motor excitation inductance two ends, when us impact, due to L _m' > > L _σ', ignore L _m' on the electric current that flows through, have following formula to set up:

$u_s=i_s*(R_s+R_r)+{L_{\mathrm{\&sigma;}}}^{\&prime;}*\frac{{\mathrm{di}}_s}{dt}$

L _σ' metering system be: measuring circuit is carried on the three-phase circuit of threephase asynchronous machine, this test loop comprises the test circuit of three groups of parallel connections, often organize the IGBT that test circuit comprises two series connection, every circuit of three-phase circuit respectively respective one_to_one corresponding is connected with wherein one group of test circuit, on the circuit of tie point between two IGBT, on each IGBT, equal conducting is provided with a diode, for sampling to every circuit, test circuit is by DC power supply, according to the current data to every circuit sampling, by calculating motor stator resistance value, testing procedure is:

Make pipe conducting on A phase brachium pontis, B pipe conducting under C phase brachium pontis, voltage u _dcbe added on A-BC end, as stator current i _areach the peak value i of rated current ₂time, record current time t ₂, then under making pipe on A phase brachium pontis turn off, pipe conducting allows electric current by D4 diode continuousing flow.

When current attenuation is to i ₃=i ₂* e ^-1time, record now moment t ₃, and make B under C phase brachium pontis pipe turn off upper pipe conducting, allow voltage _ u _dcbe added on u _a-BCend.

Work as i _aarrive reverse rated current peak value, record now moment t ₄, and under again making A phase brachium pontis, the upper pipe conducting of pipe shutoff allows electric current by D1 diode continuousing flow.

At t ₅=t ₄+ Δ t record current i ₅, at t ₆=t ₅+ Δ t record current i ₆, wherein Δ t=ln2 × (t ₃-t ₂)

Finally obtain: $L_{\mathrm{\&sigma;}}=-\frac{2u_{dc}}{3}*\frac{t_3-t_4}{i_3-\frac{{i_5}^2}{i_6}}.$