CN102393507B - Motor parameter detection method and motor parameter detection device - Google Patents

Abstract

The invention discloses a motor parameter detection method and a motor parameter detection device. The motor parameter detection method comprises the following steps: opening the circuit of one of phase windings of a motor; detecting stator leakage inductance and rotor leakage inductance; applying rated voltage with higher frequency than rated power between the other two phases of the motor; and detecting the stator leakage inductance and the rotor leakage inductance according to the computational formula of the stator leakage inductance and the rotor leakage inductance. The invention provides the off-line motor parameter detection method and the motor parameter detection device under the static condition of the rotor of an induction motor, which achieve high accuracy of motor parameter detection through reducing the influences of voltage errors and a skin effect as long as current or voltage with different frequencies is applied between the two phases of the motor in sequence.

Description

A kind of parameter of electric machine detection method and motor parameter-detecting device

Technical field

The present invention relates to a kind of parameter of electric machine detection method and motor parameter-detecting device.

Background technology

Induction motor has simple in structure, without winding, easily manufactured on rotor, and low price is easy to maintenance, the advantages such as long service life, so application scenario is very extensive.Along with the development of Power Electronic Technique and modern control theory, high-performance induction motor speed regulation system arises at the historic moment.Usually, high-performance induction motor speed regulation system often adopts vector control algorithm or the Speedless sensor algorithm of frequency converter, and the performance of these Electric Machine Control algorithms depends on the order of accuarcy of the parameter of electric machine that wherein used, if the parameter of electric machine is inaccurate, will directly causes Control performance standard to decline and even cause frequency converter failure.Therefore, how to obtain accurately the key that induction motor parameter becomes high-performance motor control algolithm.

Parameter of electric machine detection method mainly contains online detection and two kinds of methods of offline inspection.Online test method is because process is complicated, and program calculated amount is large, thereby requires processor to have higher processing speed, strict to System Hardware Requirement, is difficult to obtain practicality in engineering.

Conventional induction motor offline parameter measuring method need to be carried out no load test and stall experiment to motor.But, at motor with mechanical load in particular cases, cannot carry out no load test.At this moment need motor and load to depart from completely, and this is usually trouble, and if motor to be controlled is the ingredient of the physical construction of load, sometimes or even impossible.

For above-mentioned problem, the induction motor off-line checking method based on frequency converter, stationary rotor just began one's study from the nineties early stage in last century.Induction motor parameter comprises: fixed rotor resistance, rotor leakage inductance and magnetizing inductance (weighed rotor mutual inductance again).Induction motor equivalent circuit diagram when Fig. 1 has provided stationary rotor, wherein: r ₁for stator resistance, r ₂for rotor resistance, L _mfor magnetizing inductance, ω is electric current angular frequency, L _l1for stator leakage inductance, L _l2for rotor leakage inductance.To induction motor, pass into the setting current i of different frequency ₁, detect motor stator voltage U ₁, through certain algorithm, can calculate the parameter of electric machine.

While adopting frequency converter to measure the parameter of electric machine, for the consideration that reduces cost, generally do not use voltage sensor, but adopt detection DC bus-bar voltage to combine reconstruct output voltage, i.e. stator voltage in conjunction with frequency converter device output switch.Due to the impact of the Dead Time of frequency converter output switch device, stator voltage detects and has larger error, and especially, when input voltage is lower, error effect is larger.In order to reduce the impact of stator voltage error, in existing stationary rotor parameter of electric machine detection method, the accuracy that often improves parameter detecting by some voltage compensation measures.But in actual applications,, non-linear due to switching device, is difficult to bucking voltage error accurately.The method that another kind reduces voltage error impact is to strengthen voltage, but strengthen voltage, need improve power frequency simultaneously, when detection rotor impedance, can produce error due to kelvin effect like this.

Summary of the invention

The object of the invention is to the defect for prior art, a kind of parameter of electric machine detection method and motor parameter-detecting device are provided.

For achieving the above object, the present invention is by the following technical solutions:

A detection method, opens a way a wherein phase winding of motor;

Detect stator leakage inductance and rotor leakage inductance step: between the other two-phase of motor, apply the rated voltage that frequency ratio rated power is high, according to the computing formula of stator leakage inductance and rotor leakage inductance, detect stator leakage inductance and rotor leakage inductance.

A kind of motor parameter-detecting device, comprise stator leakage inductance and rotor leakage inductance detecting unit, described stator leakage inductance and rotor leakage inductance detecting unit apply the rated voltage that frequency ratio rated power is high between the other two-phase at motor when a wherein phase winding disconnection of motor, calculate stator leakage inductance and rotor leakage inductance.

The present invention is with respect to above-mentioned prior art, its beneficial effect is: the invention provides parameter of electric machine off-line checking method and motor parameter-detecting device in the static situation of a kind of induction electromotor rotor, only need between the two-phase of motor, to apply successively the curtage of different frequency, and reach by reducing the impact of voltage error and kelvin effect the pinpoint accuracy that the parameter of electric machine detects.

Accompanying drawing explanation

In order to be illustrated more clearly in the technical scheme in the embodiment of the present invention, below the accompanying drawing of required use during embodiment is described is briefly described.

Fig. 1 is equivalent circuit diagram when rotor is static in prior art;

Fig. 2 is the control block diagram of the parameter of electric machine offline inspection of the embodiment of the present invention;

Fig. 3 is the current step response wave shape schematic diagram of the embodiment of the present invention;

Fig. 4 is induction motor schematic equivalent circuit under the high frequency of the embodiment of the present invention;

Fig. 5 is embodiment of the present invention induction motor equiva lent impedance figure.

Embodiment

Below in conjunction with the accompanying drawing in the embodiment of the present invention, the technical scheme in the embodiment of the present invention is clearly and completely described, obviously, described embodiment is only the present invention's part embodiment, rather than whole embodiment.Embodiment based in the present invention, those of ordinary skills, not making the every other embodiment obtaining under creative work prerequisite, belong to the scope of protection of the invention.

The present invention relates to a kind of parameter of electric machine detection method, comprise and detect stator leakage inductance and rotor leakage inductance step: between the other two-phase of motor, apply the rated voltage that frequency ratio rated power is high, according to the computing formula of stator leakage inductance and rotor leakage inductance, detect stator leakage inductance and rotor leakage inductance.

Between the other two-phase of motor, apply the rated voltage that frequency ratio rated power is high, detect rotor leakage inductance, apply electric voltage frequency ω ₁than motor rated frequency ω _nhigh a lot of rated voltage, described in apply frequency and be at least greater than four times of rated frequencies, now magnetizing inductance L _melectric current can be very little, meanwhile, stator resistance r ₁with rotor resistance r ₂on pressure drop also smaller, the induction motor equivalent electrical circuit shown in Fig. 1 can be reduced to shown in Fig. 4.Because rotor leakage inductance is little more a lot of than magnetizing inductance, so approximate, think stator leakage inductance L _l1with rotor leakage inductance L _l2identical, i.e. L _l1=L _l2=L ₁.Now the amplitude of voltage and current ratio is similar to 2 ω L _l.In the control block diagram shown in Fig. 2, α shaft current set-point i _{a_ref}be made as i _{a_ref}=i _nsin ω ₁t, wherein i _nfor motor rated current.Detect DC bus-bar voltage U _dc, utilize voltage reconstructing method to obtain stator voltage U _aso,, the calculation expression of rotor leakage inductance is:

$L_l=\frac{U_a}{2{\mathrm{\ω}}_1{i}_N}$

Parameter of electric machine detection method also comprises: detect motor stator resistance step: between the other two-phase of motor, apply pulsed dc voltage, detect motor stator resistance;

Detect rotor time constant step: between the other two-phase of motor, apply step DC voltage, measure not in the same time and the current value in this moment draw electric current-time linear equation the approximate value that the current value in zero moment and described motor stator resistance substitution electric current-time linear equation are drawn to rotor time constant.

Described detection motor stator resistance step also comprises: adopt formula r ₁=U _dcd/2i calculates motor stator resistance, wherein, and U _dcfor DC bus-bar voltage, i is electric machine phase current, and the clock period is T _s, pulse width is t, the dutycycle D=t/T of pulse _s.

As shown in Figure 2, make the switching tube VT1 conducting always of inverter bridge, switching tube VT2, VT3, VT5, VT6 turn-off always, and switching tube VT4 is driven by pulse train, on a, b two phase windings, has produced a sequence of voltage pulses.If DC bus-bar voltage is U _dc, the clock period is T _s, pulse width is t, the theoretical dutycycle D=t/T of pulse _s, the average voltage on winding is U _dcd, obtains an equivalent DC voltage, and corresponding stator resistance value is r ₁=U _dcd/2i, i is electric machine phase current.

In actual testing process, in order to prevent the overcurrent fault of frequency converter in testing process, the setting of dutycycle should correctly be considered.In this method, adopt electric current loop to add the method that pi regulator draws dutycycle D and control its size, prevent excess current.As shown in Figure 2, in two-phase rest frame, α shaft current set-point i _{a_ref}be made as motor load current value, detect motor biphase current i _aand i _b, through clake, conversion obtains α axle feedback current i _{a_fbd}, through pi regulator, obtain α shaft voltage set-point u _{α ref}, and β shaft voltage set-point u _{β ref}directly be made as zero, can guaranteeing in Fig. 2 b phase, identical with the control signal of c phase brachium pontis (in fact, the VT5 in our control chart 2 and VT6 pipe turn-off all the time, and like this, motor is equivalent to a phase and b is in series; Otherwise, be to be in series with a again after b and c are in parallel).So the calculation expression of stator resistance is:

Described detection rotor time constant step also comprises: at moment t1 place, measure current value

i _step| _t=∞with

difference be I _a, set

draw another t2 constantly.

In Fig. 1 induction motor equivalent electrical circuit, electric current is as follows to transport function G (s) expression formula of the ratio of voltage,

$G\left(s\right)=\frac{1}{r_1}\frac{1+T_{r}s}{1+(T_r+T_s)s+\mathrm{\σ}{T}_s{T}_r{s}^2}$

In formula, s is Laplace operator, T _sfor stator time constant, T _rfor rotor time constant, magnetic leakage factor

l ₂for inductor rotor L ₂=L _m+ L _l.For above formula, at angular frequency (T _s+ T _r)/σ T _st _rin [rad/s] very low frequency, can be approximated to be:

$G\left(s\right)\≅\frac{1}{r_1}\frac{1+T_{r}s}{1+(T_r+T_s)s}=\frac{T_r}{r_1(T_s+T_r)}+\frac{T_s}{r_1(T_s+T_r)}\frac{1}{1+(T_r+T_s)s}$

Suppose that induction motor three-phase input voltage when original state is zero; Zero plays input step voltage U constantly _step, current i _stepfollowing voltage produces.Now current-responsive as shown in Figure 4.Current i _stepend value be:

$i_{\mathrm{step}}{|}_{t=\∞}=\frac{U_{\mathrm{step}}}{r_1}$

Electric current initial value i _step| _t=0by initial-value theorem, obtained,

$i_{\mathrm{step}}{|}_{t=0}=\frac{T_r}{T_s+T_r}\·i_{\mathrm{step}}{|}_{t=\∞}=\frac{T_r}{T_s+T_r}\·\frac{U_{\mathrm{step}}}{r_1}$

Wherein current-responsive time constant is (T _s+ T _r).

For fear of the impact of higher hamonic wave in step voltage, at experience σ T _st _r/ (T _s+ T _r) [sec] fully long-time moment t afterwards ₁place is measured

i _step| _t=∞with difference be I _a.Determine t ₁afterwards, measure current i _stepanother one t constantly ₂with following formula, obtain.

$i_{\mathrm{step}}{|}_{t=\∞}{-i}_{\mathrm{step}}{|}_{t{=t}_2}=0.5I_a$

Time constant (the T of current amplitude one half _s+ T _r) be,

$0.5=-e^{\frac{t_2-t_1}{T_s+T_r}}$

According to above formula, can obtain (T _s+ T _r) expression formula be,

$T_s+T_r=-\frac{t_2-t_1}{\ln \left(0.5\right)}=1.442(t_2-t_1)$

In Fig. 4, A point and B point line and the longitudinal axis meet at C point, and C point can be similar to and replace i _step| _t=0.At this moment have,

$i_{\mathrm{step}}{|}_{t=0}=\frac{T_r}{T_s+T_r}\·\frac{U_{\mathrm{step}}}{r_1}\≅\frac{U_{\mathrm{step}}}{r_1}-I_c=\frac{U_{\mathrm{step}}}{r_1}-\frac{I_a(2t_2-t_1)}{2(t_2-t_1)}$

$T_r\≈[1-\frac{I_a(2t_2-t_1)}{2(t_2-t_1)}\·\frac{r_1}{U_{\mathrm{step}}}](T_s+T_r)$

By the T calculating before _s+ T _rsubstitution above formula obtains,

$T_r\≈1.442[\left(t_2{-t}_1\right)-\frac{I_a(2t_2-t_1)}{2}\·\frac{r_1}{U_{\mathrm{step}}}]$

The invention provides the parameter of electric machine off-line checking method in the static situation of a kind of induction electromotor rotor, only need between the two-phase of motor, to apply successively step DC voltage, and first measure motor stator resistance, utilize motor stator resistance measurement rotor time constant, reduce calculation procedure, promoted work efficiency.

After detecting rotor time constant step, also comprise detection rotor resistance and magnetizing inductance step: between the other two-phase at motor, apply the alternating current of rated slip frequency, detection rotor resistance and magnetizing inductance.

Between the other two-phase of motor, apply the alternating current of rated slip frequency, detection rotor resistance and magnetizing inductance.In induction motor equivalent electrical circuit Fig. 1, all loads can be equivalent to a reactance Z.T-shaped equivalent electrical circuit in figure becomes and is illustrated in fig. 5 shown below.

In figure, the real part Re (Z) of Z and imaginary part Im (Z) expression formula are as follows,

$\mathrm{Re}\left(Z\right)=r_1+\frac{{\mathrm{\ω}}^2{L}_1{T}_r(1-\mathrm{\σ})}{1+{\mathrm{\ω}}^2{T}_r^2}$

$\mathrm{Im}\left(Z\right)=\mathrm{\ω}{L}_2+\frac{1+{\mathrm{\σ\ω}}^2{T}_r^2}{1+{\mathrm{\ω}}^2{T}_r^2}$

In formula, L ₁for stator inductance, L ₂for inductor rotor, and L ₁=L ₂.

Due to the impact of the Dead Time of frequency converter output switch device, stator voltage detects and has larger error, and especially, when input voltage is lower, error effect is larger.In order to reduce the impact of stator voltage error, can improve by dead area compensation measure the accuracy of parameter detecting.But in actual applications,, non-linear due to switching device, is difficult to compensate accurately dead band voltage error.On the other hand, the voltage error and the current polarity that by Dead Time, are caused are contrary.That is to say, stator voltage error is synchronous with stator current in the ideal case, there is no this impact with the voltage segment of electric current quadrature.Stator voltage is Re (Z) with the ratio of stator current same-phase, stator voltage is Im (Z) with the ratio that stator current orthogonal part is divided, so utilize Im (Z) to remove to calculate rotor resistance and magnetizing inductance, can eliminate the impact that the voltage error that caused by frequency converter output switch device Dead Time brings completely.

The accuracy detecting in order to improve as much as possible rotor resistance and magnetizing inductance, the α shaft current set-point I in Fig. 2 _{a_ref}frequency must select suitable value.If it is too low that this frequency is selected, compare excitation reactance ω L with rotor loop reactance _mvery little.Electric current mainly passes through energized circuit like this, makes rotor resistance r ₂be not easy to obtain.If it is too high that this frequency is selected, excitation reactance ω L _mincrease, the electric current of flowing through diminishes, leakage inductance L _lon voltage drop become large, Im (Z) is subject to leakage inductance to affect increase, and due to kelvin effect, makes rotor resistance r ₂measuring error further strengthens.Experiment is found, as α shaft current set-point i _{a_ref}angular frequency be ω _ref=2 π/T _rtime, testing result is pressed close to actual value.

α shaft current set-point i _{a_ref}be made as,

$i_{\mathrm{\α}\_\mathrm{ref}}=\sqrt{2}{I}_N\cos \left({\mathrm{\ω}}_{\mathrm{ref}}t\right)$

When electric current reaches after setting value, between U, V two-phase, having produced a fundamental frequency is ω _ref, fundamental voltage amplitude is U _msine pulse width modulation (PWM) voltage.Store electric current and the voltage sample value of one-period, through FFT, calculate the phase differential θ of voltage and current, current first harmonics amplitude I _m.Stator voltage amplitude can obtain by reconstruction calculations.So imaginary part Im (Z) is

$\mathrm{Im}\left(Z\right)=\frac{U_m{I}_m\sin \mathrm{\θ}}{2I_m^2}$

The imaginary part Im obtaining before this (Z) expression formula is arranged,

$\frac{{\mathrm{\ω}}_{\mathrm{ref}}^2}{r_2^2}(2{\mathrm{\ω}}_{\mathrm{ref}}{L}_l-\mathrm{Im}\left(Z\right))L_2^2+(1-\frac{{\mathrm{\ω}}_{\mathrm{ref}}^2}{r_2^2}{L}_l){\mathrm{\ω}}_{\mathrm{ref}}{L}_2-\mathrm{Im}\left(Z\right)=0$

By T _r=L ₂/ r ₂substitution above formula obtains,

${\mathrm{\ω}}_{\mathrm{ref}}{L}_2^2+[{\mathrm{\ω}}_{\mathrm{ref}}^2{T}_r^2(2{\mathrm{\ω}}_{\mathrm{ref}}{L}_l-\mathrm{Im}\left(Z\right))-\mathrm{Im}\left(Z\right)]L_2-{\mathrm{\ω}}_{\mathrm{ref}}^3{T}_r^2{L}_l=0$

By separating quadratic equation with one unknown, obtain the inductor rotor L needing ₂, magnetizing inductance is,

L _m＝L ₂-L _l

Rotor resistance is

$r_2=\frac{L_2}{T_r}$

The invention provides the parameter of electric machine off-line checking method in the static situation of a kind of induction electromotor rotor, the method only needs between the two-phase of motor, to apply successively the curtage of different frequency, and reach by reducing the impact of voltage error and kelvin effect the pinpoint accuracy that the parameter of electric machine detects, first calculate rotor leakage inductance, then first measure motor stator resistance, utilize motor stator resistance measurement rotor time constant, finally calculate magnetizing inductance and rotor resistance, reduce calculation procedure, promoted work efficiency.

A kind of motor parameter-detecting device, comprise stator leakage inductance and rotor leakage inductance detecting unit, described stator leakage inductance and rotor leakage inductance detecting unit apply the rated voltage that frequency ratio rated power is high between the other two-phase at motor when a wherein phase winding disconnection of motor, calculate stator leakage inductance and rotor leakage inductance.

Described stator leakage inductance and rotor leakage inductance detecting unit adopt formula

obtain described stator leakage inductance, described rotor leakage inductance equals stator leakage inductance, wherein U _afor stator voltage, i _nfor motor rated current, ω ₁for applying frequency.

Also comprise motor stator resistance detection unit and rotor time constant detecting unit, described motor stator resistance detection unit applies pulsed dc voltage between the other two-phase at motor when a wherein phase winding disconnection of motor, detects motor stator resistance; Described rotor time constant detecting unit applies step DC voltage between the other two-phase at motor when a wherein phase winding disconnection of motor, measure not in the same time and the current value in this moment draw electric current-time linear equation, and the approximate value that draws rotor time constant according to the current value in zero moment and described motor stator resistance.

Described motor stator resistance detection unit adopts formula r ₁=U _dcd/2i calculates motor stator resistance, wherein, and U _dcfor DC bus-bar voltage, i is electric machine phase current, and the clock period is T _s, pulse width is t, the dutycycle D=t/T of pulse _s.

Described rotor time constant detecting unit adopts formula

be similar to and draw rotor time constant, wherein, U _stepbe zero moment to play input step magnitude of voltage.

Also comprise rotor resistance and magnetizing inductance detecting unit, rotor resistance and magnetizing inductance detecting unit apply the alternating current of rated slip frequency, detection rotor resistance and magnetizing inductance when a wherein phase winding disconnection of motor between the other two-phase at motor.

Described detection rotor resistance and magnetizing inductance detecting unit adopt formula

${\mathrm{\ω}}_{\mathrm{ref}}{L}_2^2+[{\mathrm{\ω}}_{\mathrm{ref}}^2{T}_r^2(2{\mathrm{\ω}}_{\mathrm{ref}}{L}_l-\mathrm{Im}\left(Z\right))-\mathrm{Im}\left(Z\right)]L_2-{\mathrm{\ω}}_{\mathrm{ref}}^3{T}_r^2{L}_l=0$

Calculate inductor rotor L ₂, adopt formula L _m=L ₂-L _lcalculate magnetizing inductance, adopt formula

calculate rotor resistance.

The invention provides motor parameter-detecting device in the static situation of a kind of induction electromotor rotor, only need between the two-phase of motor, to apply successively the curtage of different frequency, and reach by reducing the impact of voltage error and kelvin effect the pinpoint accuracy that the parameter of electric machine detects, first calculate rotor leakage inductance, then first measure motor stator resistance, utilize motor stator resistance measurement rotor time constant, finally calculate magnetizing inductance and rotor resistance, reduce calculation procedure, promoted work efficiency.

Applied specific case herein principle of the present invention and embodiment are set forth, the explanation of above embodiment is just for helping to understand method of the present invention and core concept thereof; , for those of ordinary skill in the art, according to thought of the present invention, all will change in specific embodiments and applications, in sum, this description should not be construed as limitation of the present invention meanwhile.

Claims (11)

1. a parameter of electric machine detection method, is characterized in that:

Make a wherein phase winding open circuit of motor;

Detect stator leakage inductance and rotor leakage inductance step: between the other two-phase of motor, apply the rated voltage that frequency ratio rated power is high, according to the computing formula of stator leakage inductance and rotor leakage inductance, detect stator leakage inductance and rotor leakage inductance; The described frequency that applies is at least greater than four times of rated frequencies; Detecting stator leakage inductance and rotor leakage inductance step also comprises: adopt formula

obtain described stator leakage inductance, described rotor leakage inductance equals stator leakage inductance, wherein U _afor stator voltage, i _nfor motor rated current, ω ₁for applying frequency.

2. parameter of electric machine detection method as claimed in claim 1, is characterized in that: also comprise:

Detect motor stator resistance step: between the other two-phase of motor, apply pulsed dc voltage, detect motor stator resistance;

Detect rotor time constant step: between the other two-phase of motor, apply step DC voltage, measure not in the same time and the current value in this moment draw electric current-time linear equation the approximate value that the current value in zero moment and described motor stator resistance substitution electric current-time linear equation are drawn to rotor time constant.

3. parameter of electric machine detection method as claimed in claim 2, is characterized in that: described detection motor stator resistance step also comprises: adopt formula r ₁=U _dcd/2i calculates motor stator resistance, wherein, and U _dcfor DC bus-bar voltage, i is electric machine phase current, and the clock period is T _s, pulse width is t, the dutycycle D=t/T of pulse _s.

4. parameter of electric machine detection method as claimed in claim 3, is characterized in that: described detection rotor time constant step also comprises: at moment t ₁current value is measured at place i _step| _t=∞with

difference be I _a, set

draw another t constantly ₂.

5. parameter of electric machine detection method as claimed in claim 4, is characterized in that: described detection rotor time constant step also comprises: adopt formula

be similar to and draw rotor time constant, wherein, U _stepbe zero moment to play input step magnitude of voltage.

6. parameter of electric machine detection method as claimed in claim 5, is characterized in that: detection rotor resistance and magnetizing inductance step comprise: adopt formula

${\mathrm{\ω}}_{\mathrm{ref}}{L}_2^2+[{\mathrm{\ω}}_{\mathrm{ref}}^2{T}_r^2({2\mathrm{\ω}}_{\mathrm{ref}}{L}_l-\mathrm{Im}\left(Z\right))-\mathrm{Im}\left(Z\right)]L_2-{\mathrm{\ω}}_{\mathrm{ref}}^3{T}_r^2{L}_l=0$

Calculate inductor rotor L ₂, adopt formula L _m=L ₂-L _lcalculate magnetizing inductance, adopt formula

calculate rotor resistance, wherein, stator voltage is Im (Z) with the ratio that stator current orthogonal part is divided.

7. a motor parameter-detecting device, it is characterized in that: comprise stator leakage inductance and rotor leakage inductance detecting unit, described stator leakage inductance and rotor leakage inductance detecting unit apply the rated voltage that frequency ratio rated power is high between the other two-phase at motor when a wherein phase winding disconnection of motor, calculate stator leakage inductance and rotor leakage inductance; Described stator leakage inductance and rotor leakage inductance detecting unit adopt formula

obtain described stator leakage inductance, described rotor leakage inductance equals stator leakage inductance, wherein U _afor stator voltage, i _nfor motor rated current, ω ₁for applying frequency.

8. motor parameter-detecting device as claimed in claim 7, is characterized in that: also comprise motor stator resistance detection unit and rotor time constant detecting unit,

Described motor stator resistance detection unit applies pulsed dc voltage between the other two-phase at motor when a wherein phase winding disconnection of motor, detects motor stator resistance;

Described rotor time constant detecting unit applies step DC voltage between the other two-phase at motor when a wherein phase winding disconnection of motor, measure not in the same time and the current value in this moment draw electric current-time linear equation, and the approximate value that draws rotor time constant according to the current value in zero moment and described motor stator resistance.

9. motor parameter-detecting device as claimed in claim 8, is characterized in that: described motor stator resistance detection unit adopts formula r ₁=U _dcd/2i calculates motor stator resistance, wherein, and U _dcfor DC bus-bar voltage, i is electric machine phase current, and the clock period is T _s, pulse width is t, the dutycycle D=t/T of pulse _s.

10. motor parameter-detecting device as claimed in claim 9, is characterized in that: described rotor time constant detecting unit adopts formula be similar to and draw rotor time constant, wherein, U _stepbe zero moment to play input step magnitude of voltage, at moment t ₁current value is measured at place

i _step| _t=∞with

difference be I _a, set draw another t constantly ₂.

11. motor parameter-detecting devices as claimed in claim 10, is characterized in that: detection rotor resistance and magnetizing inductance detecting unit adopt formula

${\mathrm{\ω}}_{\mathrm{ref}}{L}_2^2+[{\mathrm{\ω}}_{\mathrm{ref}}^2{T}_r^2({2\mathrm{\ω}}_{\mathrm{ref}}{L}_l-\mathrm{Im}\left(Z\right))-\mathrm{Im}\left(Z\right)]L_2-{\mathrm{\ω}}_{\mathrm{ref}}^3{T}_r^2{L}_l=0$

Calculate inductor rotor L ₂, adopt formula L _m=L ₂-L _lcalculate magnetizing inductance, adopt formula

calculate rotor resistance, wherein, ω _ref=2 π/T _r, stator voltage is Im (Z) with the ratio that stator current orthogonal part is divided.

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