CN102353842B - Measuring method for stator resistance of asynchronous motor - Google Patents

Abstract

The invention relates to the power electronic technology field, more particularly to a measuring method for a stator resistance of an asynchronous motor. Compared with the prior art, the technology employed in the invention enables the method to have the following characteristics that: two vector voltages with 180 degrees of an electrical angle difference are employed to carry out alternatively working in a same time, and thus measurement on a stator resistance of an asynchronous motor will not be influenced by a tube voltage drop UIGBT of an insulated gate bipolar transistor, an open time ton of the insulated gate bipolar transistor, and a turn-off time toff of the insulated gate bipolar transistor, so that an accuracy of the measurement on the stator resistance of the asynchronous motor is higher.

Description

A kind of measuring method of stator resistance of asynchronous motor

Technical field

The present invention relates to electric and electronic technical field, specifically a kind of measuring method of stator resistance of asynchronous motor.

Background technology

Usually, the stator resistance of asynchronous machine adopts DC va method to measure.Concrete grammar is as follows: the vector voltage getting the adjacent 60 ° of electrical angles of two-phase in Fig. 1, i.e. [10z] and [z0z] (z represents brachium pontis open circuit high resistant).As shown in Figure 3, when [10z] and [z0z] two-phase alternation, namely produce a DC voltage U be added on asynchronous machine stator coil _m, as shown in Figure 4, its value is $U_m=U_{\mathrm{DC}}\·D=U_{\mathrm{DC}}\·\frac{t\left[10z\right]}{t\left[10z\right]+t\left[z0z\right]}=U_{\mathrm{DC}}\frac{t_{\mathrm{on}}}{T},$ The stator resistance of asynchronous machine $R_S=\frac{U_m}{2I}=\frac{U_{\mathrm{DC}}\·D}{2I}.$

In the method, DC voltage U _mbe subject to the tube voltage drop U of insulated gate bipolar transistor _iGBT, fly-wheel diode tube voltage drop U _dIODE, insulated gate bipolar transistor service time t _on, insulated gate bipolar transistor turn-off time t _offwith for preventing the Dead Time t opened during upper and lower bridge arm conducting _dtimpact.Specific as follows:

$U_m=[U_{\mathrm{DC}}-(U_{\mathrm{IGBT}}+U_{\mathrm{DIODE}})]\×\frac{t\left[10z\right]-(t_{\mathrm{Dt}}+t_{\mathrm{on}}+t_{\mathrm{off}})}{T}$

Make U _iGBT+ U _dIODE=Δ U, t _dt+ t _on+ t _off=Δ t,

$\mathrm{\ΔD}=\frac{\mathrm{\Δt}}{T},$ $D=\frac{t\left[10z\right]}{T},$ U _e＝D·ΔU+U _DC·ΔD-ΔU·ΔD

Can obtain, U _m=U _dCd-(D Δ U+U _dCΔ D-Δ U Δ D)

Known by above formula, the accuracy that stator resistance of asynchronous motor is measured is subject to the tube voltage drop U of insulated gate bipolar transistor _iGBT, insulated gate bipolar transistor service time t _onwith the turn-off time t of insulated gate bipolar transistor _offimpact.

Therefore, the accuracy impregnable stator resistance of asynchronous motor measuring method of inventing a kind of measurement result is vital.

Summary of the invention

The object of the invention is to overcome the deficiencies in the prior art, provide and a kind ofly can make the impregnable stator resistance of asynchronous motor measuring method of the accuracy of measurement result.

In order to achieve the above object, the present invention includes following steps: step 1, choose first-phase vector voltage [10z] and second-phase vector voltage [01z], the electrical angle difference of described first-phase vector voltage [10z] and described second-phase vector voltage [01z] is 180 °, makes described first-phase vector voltage [10z] and described second-phase vector voltage [01z] alternation within equal time; Step 2, goes out the DC voltage Um of asynchronous machine stator coil according to formulae discovery; Step 3, by PI Current adjustment, goes out the DC voltage U of asynchronous machine stator coil according to formulae discovery _m0; Step 4, again by PI Current adjustment, goes out the DC voltage U of asynchronous machine stator coil according to formulae discovery _m1; Step 5, calculates the average voltage U of asynchronous machine stator coil _n; Step 6, calculates stator resistance of asynchronous motor R by software _s.

Described software completes following steps: step 1, according to motor nameplate setting parameter time t _[10z]; Step 2, the copped wave of starting impulse width modulated; Step 3, judges the electric current I of first-phase vector voltage _[10z]whether be greater than the electric current I of second-phase vector voltage _[01z], if so, then carry out step 4, if not, then carry out step 5; Step 4, time t _[10z]subtract one, cycle T adds one, carry out step 3 after completing; Step 5, judges the electric current I of first-phase vector voltage _[10z]whether be less than the electric current I of second-phase vector voltage _[01z], if so, then carry out step 6, if not, then carry out step 7; Step 6, time t _[10z]add one, cycle T subtracts one, carry out step 5 after completing; Step 7, holding time t _[10z]; Step 8, judges the electric current I of first-phase vector voltage _[10z]with the electric current I of second-phase vector voltage _[01z]difference whether be greater than electric current I, if so, then carry out step 9, if not, then carry out step 10; Step 9, time t _[10z]subtract one, cycle T adds one, carry out step 8 after completing; Step 10, judges the electric current I of first-phase vector voltage _[10z]with the electric current I of second-phase vector voltage _[01z]difference whether be less than electric current I, if so, then carry out step 11, if not, then carry out step 12; Step 11, time t _[10z]add one, cycle T subtracts one, carry out step 10 after completing; Step 12, holding time t _[10z]and according to formulae discovery stator resistance of asynchronous motor R _s.

The present invention compared with the existing technology, adopt electrical angle difference be two vector voltages of 180 ° in alternation equal time, make the measurement of stator resistance of asynchronous motor not be subject to the tube voltage drop U of insulated gate bipolar transistor _iGBT, insulated gate bipolar transistor service time t _onwith the turn-off time t of insulated gate bipolar transistor _offimpact, thus the accuracy that stator resistance of asynchronous motor is measured is higher.

Accompanying drawing explanation

Fig. 1 is vector voltage schematic diagram.

Fig. 2 is the circuit diagram of [10z].

Fig. 3 is the circuit diagram of prior art [z0z].

Fig. 4 is the oscillogram of prior art.

Fig. 5 is the circuit diagram of the present invention [01z].

Fig. 6 is oscillogram of the present invention.

Fig. 7 is software flow schematic diagram of the present invention

Embodiment

Now by reference to the accompanying drawings the present invention is described further.

See Fig. 2, Fig. 5 and Fig. 6, the present invention includes following steps: step 1, choose first-phase vector voltage [10z] and second-phase vector voltage [01z], the electrical angle difference of first-phase vector voltage [10z] and second-phase vector voltage [01z] is 180 °, makes first-phase vector voltage [10z] and second-phase vector voltage [01z] alternation within equal time.

Step 2, goes out the DC voltage U of asynchronous machine stator coil according to formulae discovery _m, concrete computation process is as follows:

Interval at [10z], have $I_{\left[10Z\right]}=\frac{U_{\mathrm{DC}}-\mathrm{\ΔU}}{2R_S};$ Interval at [01z], have $-I_{\left[01Z\right]}=\frac{-(U_{\mathrm{DC}}-\mathrm{\ΔU})}{2R_S};$

If t _[10Z]=t _[01Z], then T=t _[10Z]+ t _[01Z]; Then $U_m=U_{\mathrm{DC}}\·D-U_e=U_{\mathrm{DC}}\·\frac{t_{\left[10Z\right]}}{t_{\left[10Z\right]}+t_{\left[01Z\right]}}-U_e.$

Step 3, by PI Current adjustment, goes out the DC voltage U of asynchronous machine stator coil according to formulae discovery _m0, concrete computation process is as follows: work as t _[10Z]+ Δ t ₁time, t _[01Z]-Δ t ₁; Then T=t _[10Z]+ Δ t ₁+ t _[01Z]-Δ t ₁; I _[10Z]-I _[01Z]=0; $U_{m0}=U_{\mathrm{DC}}\·\frac{t_{\left[10Z\right]}}{T}+\frac{\mathrm{\Δ}{t}_1}{T}\·U_{\mathrm{DC}}-U_e.$

Step 4, again by PI Current adjustment, goes out the DC voltage U of asynchronous machine stator coil according to formulae discovery _m1, concrete computation process is as follows: work as t _[10Z]+ Δ t ₁+ Δ t ₂, t _[01Z]-Δ t ₁-Δ t ₂time;

Then T=t _[10Z]+ Δ t ₁+ Δ t ₂+ t _[01Z]-Δ t ₁-Δ t ₂time; I _[10Z]-I _[01Z]=I

Then $U_{m1}=U_{\mathrm{DC}}\·\frac{t_{\left[10Z\right]}}{T}+\frac{{\mathrm{\Δt}}_2}{T}\·U_{\mathrm{DC}}+\frac{{\mathrm{\Δt}}_1}{T}\·U_{\mathrm{DC}}-U_e.$

Step 5, calculates the average voltage U of asynchronous machine stator coil _n, detailed process is as follows:

$U_n=U_{m1}-U_{m0}=\frac{{\mathrm{\Δt}}_2}{T}\·U_{\mathrm{DC}}.$

Step 6, calculates stator resistance of asynchronous motor R by software _s.

See Fig. 7, software completes following steps: step 1, according to motor nameplate setting parameter time t _[10z]; Step 2, the copped wave of starting impulse width modulated; Step 3, judges the electric current I of first-phase vector voltage _[10z]whether be greater than the electric current I of second-phase vector voltage _[01z], if so, then carry out step 4, if not, then carry out step 5; Step 4, time t _[10z]subtract one, cycle T adds one, carry out step 3 after completing; Step 5, judges the electric current I of first-phase vector voltage _[10z]whether be less than the electric current I of second-phase vector voltage _[01z], if so, then carry out step 6, if not, then carry out step 7; Step 6, time t _[10z]add one, cycle T subtracts one, carry out step 5 after completing; Step 7, holding time t _[10z]; Step 8, judges the electric current I of first-phase vector voltage _[10z]with the electric current I of second-phase vector voltage _[01z]difference whether be greater than electric current I, if so, then carry out step 9, if not, then carry out step 10; Step 9, time t _[10z]subtract one, cycle T adds one, carry out step 8 after completing; Step 10, judges the electric current I of first-phase vector voltage _[10z]with the electric current I of second-phase vector voltage _[01z]difference whether be less than electric current I, if so, then carry out step 11, if not, then carry out step 12; Step 11, time t _[10z]add one, cycle T subtracts one, carry out step 10 after completing; Step 12, holding time t _[10z]newly, according to formulae discovery stator resistance of asynchronous motor R _s: Δ t ₂=t _[10z]newly-t _[10z]

U _m＝Δt ₂·U _DC

R _S＝U _m/2I。

Claims (1)

1. the measuring method of a stator resistance of asynchronous motor, it is characterized in that comprising the following steps: step 1, choose first-phase vector voltage [10z] and second-phase vector voltage [01z], the electrical angle difference of described first-phase vector voltage [10z] and described second-phase vector voltage [01z] is 180 °, makes described first-phase vector voltage [10z] and described second-phase vector voltage [01z] alternation within equal time; Step 2, calculates the DC voltage U of asynchronous machine stator coil _m: interval at [10z], have ; Interval at [01z], have ; If , then ; Then ; Step 3, by PI Current adjustment, calculates the DC voltage U of asynchronous machine stator coil _m0: when time, ; Then ; ; ; Step 4, again by PI Current adjustment, calculates the DC voltage U of asynchronous machine stator coil _m1: when , time; Then time; then ; Step 5, calculates the average voltage U of asynchronous machine stator coil _n, detailed process is as follows: ; Step 6, calculates stator resistance of asynchronous motor R by software _s; Described software completes following steps: step a, according to motor nameplate setting parameter time t _[10z]; Step b, the copped wave of starting impulse width modulated; Step c, judges the electric current I of first-phase vector voltage _[10z]whether be greater than the electric current I of second-phase vector voltage _[01z], if so, then carry out steps d, if not, then carry out step e; Steps d, time t _[10z]subtract one, cycle T adds one, carries out step c after completing; Step e, judges the electric current I of first-phase vector voltage _[10z]whether be less than the electric current I of second-phase vector voltage _[01z], if so, then carry out step f, if not, then carry out step g; Step f, time t _[10z]add one, cycle T subtracts one, carries out step e after completing; Step g, holding time t _[10z]; Step h, judges the electric current I of first-phase vector voltage _[10z]with the electric current I of second-phase vector voltage _[01z]difference whether be greater than electric current I, if so, then carry out step I, if not, then carry out step j; Step I, time t _[10z]subtract one, cycle T adds one, carries out step h after completing; Step j, judges the electric current I of first-phase vector voltage _[10z]with the electric current I of second-phase vector voltage _[01z]difference whether be less than electric current I, if so, then carry out step k, if not, then carry out step l; Step k, time t _[10z]add one, cycle T subtracts one, carries out step j after completing; Step l, holding time t _[10z], and according to formulae discovery stator resistance of asynchronous motor R _s.