CN104811116A - Method and system for estimation of slip of asynchronous motor - Google Patents

Abstract

The invention relates to the technical field of motor control, and discloses a method and system for estimation of the slip of an asynchronous motor. The method for estimation of the slip of the asynchronous motor comprises the following steps that parameters of the asynchronous motor are acquired, wherein the parameters include the stator resistance, the stator inductance, the rotor resistance, the rotor inductance and the mutual inductance between a rotor and a stator; voltage information and current information of the asynchronous motor are acquired, and are converted to be in a static two-phase coordinate system or a synchronous rotating reference frame; the slip is estimated according to a steady-state equation of the asynchronous motor, the acquired parameters, the voltage information processed through coordinate system conversion and the current information processed through coordinate system conversion. Compared with the prior art, the method and system for estimation of the slip of the asynchronous motor have the advantages that the dependency on motor control modes can be removed, and the slip is accurately calculated in various motor control modes.

Description

A kind of asynchronous machine slip method of estimation and system

Technical field

The present invention relates to motor control technology field, particularly a kind of asynchronous machine slip method of estimation and system.

Background technology

Asynchronous motor control needs slip information usually.When adopting rotor flux-oriented control, slip (ω _sl) can according to stator dq shaft current i _sd, i _sqwith rotor time constant (T _r) obtain, be shown below:

${\mathrm{\ω}}_{\mathrm{sl}}=T_r\frac{i_{\mathrm{sq}}}{i_{\mathrm{sd}}}$

Stator dq shaft current i _sd, i _sqcan be calculated by actual current value and obtain, rotor time constant (T _r) can according to rotor resistance (R _r) and inductor rotor (L _r) calculate acquisition, be shown below:

$T_r=\frac{R_r}{L_r}$

Rotor resistance (R _r) and inductor rotor (L _r) can be obtained by the method for off-line identification.

But the method for above-mentioned estimation slip is only confined to rotor flux-oriented control, if still adopt said method to estimate slip under other control modes, just result accurately can not be obtained.

Summary of the invention

The object of the present invention is to provide a kind of asynchronous machine slip method of estimation and system, the dependence to Electric Machine Control mode can be departed from, under various Electric Machine Control mode, slip is calculated exactly.

For solving the problems of the technologies described above, embodiments of the present invention provide a kind of asynchronous machine slip method of estimation, comprise following steps:

Obtain the parameter of described asynchronous machine; Described parameter comprises stator resistance, stator inductance, rotor resistance, mutual inductance between inductor rotor and stator rotor;

Obtain information of voltage and the current information of described asynchronous machine, and under described information of voltage, current information are transformed into static two phase coordinate systems or synchronous rotating frame respectively;

According to the information of voltage after the described parameter of the steady-state equation of described asynchronous machine, acquisition, converted coordinate system and the current information after converted coordinate system, estimate slip.

Embodiments of the present invention additionally provide a kind of asynchronous machine slip estimating system, comprise: parameter acquiring unit, information of voltage acquiring unit, current information acquiring unit, ordinate transform unit and slip estimation unit;

Described parameter acquiring unit, for obtaining the parameter of described asynchronous machine; Described parameter comprises stator resistance, stator inductance, rotor resistance, mutual inductance between inductor rotor and stator rotor;

Described information of voltage acquiring unit, for obtaining the information of voltage of described asynchronous machine;

Described current information acquiring unit, for obtaining the current information of described asynchronous machine;

Described ordinate transform unit, under being transformed into static two phase coordinate systems or synchronous rotating frame respectively by described information of voltage, described current information;

Described slip estimation unit, for the information of voltage after the steady-state equation according to described asynchronous machine, described parameter, converted coordinate system and the current information after converted coordinate system, estimates slip.

Embodiment of the present invention in terms of existing technologies, first obtain the parameters such as the stator resistance of asynchronous machine, stator inductance, rotor resistance, mutual inductance between inductor rotor and stator rotor, obtain information of voltage and the current information of asynchronous machine again, and under the information of voltage of acquisition and current information are transformed into static two phase coordinate systems or synchronous rotating frame respectively; Under static two phase coordinate systems or synchronous rotating frame, according to the information of voltage after the parameter of the steady-state equation of asynchronous machine, acquisition, converted coordinate system and the current information after converted coordinate system, estimate slip.Due to above-mentioned parameter, information of voltage, current information and steady-state equation, all do not rely on the control mode of motor, do not rely on rotor flux linkage orientation yet, so, the present invention can depart from the dependence to Electric Machine Control mode, calculates exactly under various Electric Machine Control mode to slip.

In addition, if under described static two phase coordinate systems, carry out slip estimation to squirrel cage asynchronous motor, the slip drawn is

Wherein, ω _slfor slip, R _rfor rotor resistance, L _rfor inductor rotor, u _{α s}for stator α shaft voltage, u _{β s}for stator β shaft voltage, i _{α s}for stator α shaft current, i _{β s}for stator β shaft current, ω _efor synchronizing frequency, L _sfor stator inductance; And l _mfor the mutual inductance between stator rotor; Or if under described synchronous rotating frame, carry out slip estimation to squirrel cage asynchronous motor, the slip drawn is

Wherein, u _dsfor stator d shaft voltage, u _qsfor stator q shaft voltage, i _dsfor stator d shaft current, i _qsfor stator q shaft current.

Accompanying drawing explanation

Fig. 1 is the flow chart of the asynchronous machine slip method of estimation according to first embodiment of the invention;

Fig. 2 is the flow chart of the asynchronous machine slip method of estimation according to second embodiment of the invention;

Fig. 3 is the block diagram of the asynchronous machine slip estimating system according to third embodiment of the invention.

Embodiment

For making the object, technical solutions and advantages of the present invention clearly, below in conjunction with accompanying drawing, the embodiments of the present invention are explained in detail.But, persons of ordinary skill in the art may appreciate that in each execution mode of the present invention, proposing many ins and outs to make reader understand the application better.But, even without these ins and outs with based on the many variations of following execution mode and amendment, each claim of the application technical scheme required for protection also can be realized.

First execution mode of the present invention relates to a kind of asynchronous machine slip method of estimation, and idiographic flow as shown in Figure 1, comprises following steps:

Step 101, obtains the parameter of asynchronous machine.Wherein, the parameter of acquisition comprises stator resistance (R _s), stator inductance (L _s), rotor resistance (R _r), inductor rotor (L _r) and stator rotor between mutual inductance (L _m).In this step, both can obtain these parameters by the mode measured, also can obtain these parameters by the mode self study of off-line identification.Off-line identification should belong to the common technology of Motor Control Field, does not repeat them here.

Step 102, obtains information of voltage and the current information of asynchronous machine.In the present embodiment, asynchronous machine is three phase alternating current motor, and the information of voltage of motor is three phase terminals information of voltage, and current information is three-phase phase current information; Wherein, three-phase phase voltage can be calculated according to three phase terminals voltage.And, in the present embodiment, the three-phase phase current (i of motor _as, i _bs, i _cs) can be obtained by current sensor sampling; Three phase terminals voltage (the u of motor _an, u _bn, u _cn) both can obtain with overvoltage sensor sampling, also can calculate according to each phase duty ratio and busbar voltage and obtain.The three-phase phase voltage of motor can according to three phase terminals voltage (u _an, u _bn, u _cn) calculated by following transformational relation:

$\left\{\begin{array}{c}{u}_{\mathrm{as}}=\frac{2}{3}{u}_{\mathrm{an}}-\frac{1}{3}{u}_{\mathrm{bn}}-\frac{1}{3}{u}_{\mathrm{cn}}\\ u_{\mathrm{bs}}=-\frac{1}{3}{u}_{\mathrm{an}}+\frac{2}{3}{u}_{\mathrm{bn}}-\frac{1}{3}{u}_{\mathrm{cn}}\\ u_{\mathrm{cs}}=-\frac{1}{3}{u}_{\mathrm{an}}-\frac{1}{3}{u}_{\mathrm{bn}}+\frac{2}{3}{u}_{\mathrm{cn}}\end{array}\right.$

Wherein, u _as, u _bswith u _csfor the three-phase phase voltage of motor.

It should be noted that, the three-phase voltage information obtained in this step and the reference frame of three-phase current information are all static three phase coordinate systems.

Step 103, under being transformed into static two phase coordinate systems respectively by the information of voltage of acquisition, current information.Wherein, static two phase coordinate systems are exactly α β coordinate system.Specifically, under respectively the information of voltage under static three phase coordinate systems, current information being transformed into static two phase coordinate systems respectively by following transformational relation

$\left\{\begin{array}{c}{u}_{\mathrm{\αs}}=\frac{2}{3}{u}_{\mathrm{as}}-\frac{1}{3}{u}_{\mathrm{bs}}-\frac{1}{3}{u}_{\mathrm{cs}}\\ u_{\mathrm{\βs}}=\frac{1}{\sqrt{3}}{u}_{\mathrm{bs}}-\frac{1}{\sqrt{3}}{u}_{\mathrm{cs}}\end{array}\right.$

$\left\{\begin{array}{c}{i}_{\mathrm{\αs}}=\frac{2}{3}{i}_{\mathrm{as}}-\frac{1}{3}{i}_{\mathrm{bs}}-\frac{1}{3}{i}_{\mathrm{cs}}\\ i_{\mathrm{\βs}}=\frac{1}{\sqrt{3}}{i}_{\mathrm{bs}}-\frac{1}{\sqrt{3}}{i}_{\mathrm{cs}}\end{array}\right.$

Wherein, u _{α s}, u _{β s}the voltage under two-phase rest frame respectively, i _{α s}, i _{β s}the electric current under two-phase rest frame respectively.

Step 104, under being converted to synchronous rotating frame respectively by the information of voltage under static two phase coordinate systems, current information.Wherein, synchronous rotating frame is exactly dq coordinate system.Specifically, under respectively the information of voltage under static two phase coordinate systems, current information being transformed into synchronous rotating frame respectively by following transformational relation

$\left\{\begin{array}{c}{u}_{\mathrm{ds}}=u_{\mathrm{\αs}}\cos \mathrm{\θ}+u_{\mathrm{\βs}}\sin \mathrm{\θ}\\ u_{\mathrm{qs}}=-u_{\mathrm{\αs}}\sin \mathrm{\θ}+u_{\mathrm{\βs}}\cos \mathrm{\θ}\end{array}\right.$

$\left\{\begin{array}{c}{i}_{\mathrm{ds}}=i_{\mathrm{\αs}}\cos \mathrm{\θ}+i_{\mathrm{\βs}}\sin \mathrm{\θ}\\ i_{\mathrm{qs}}=-i_{\mathrm{\αs}}\sin \mathrm{\θ}+i_{\mathrm{\βs}}\cos \mathrm{\θ}\end{array}\right.$

Wherein, u _ds, u _qsthe voltage under synchronous rotating frame respectively, i _ds, i _qsthe electric current under synchronous rotating frame respectively, θ=ω _et+ θ ₀, ω _efor synchronizing frequency, θ ₀for initial angle, t is the time.

Step 105, according to the information of voltage under the parameter of the steady-state equation of asynchronous machine, acquisition, synchronous rotating frame and current information, estimates slip.In present embodiment, be estimated as example to carry out slip to squirrel cage asynchronous motor, be illustrated, specific as follows:

The steady-state equation of squirrel cage asynchronous motor is as follows:

u _qs＝R _si _qs+ω _eL _si _ds+ω _eL _mi _dr

u _ds＝-ω _eL _si _qs+R _si _ds-ω _eL _mi _qr

0＝ω _slL _mi _ds+R _ri _qr+ω _slL _ri _dr

0＝-ω _slL _mi _qs-ω _slL _ri _qr+R _ri _dr

Wherein, i _drfor rotor d shaft current, i _qrfor rotor q shaft current.By steady-state equation as above, following result can be obtained,

u _dsi _ds+u _qsi _qs＝R _s(i _ds ²+i _qs ²)+Kω _eL _mR _r(i _ds ²+i _qs ²) (1)

u _dsi _qs-u _qsi _ds＝-ω _eL _s(i _ds ²+i _qs ²)+Kω _eL _mω _slL _r(i _ds ²+i _qs ²) (2)

Or

$u_{\mathrm{ds}}{i}_{\mathrm{qs}}-u_{\mathrm{qs}}{i}_{\mathrm{ds}}=-{\mathrm{\ω}}_e{L}_{\mathrm{\σ}}({i_{\mathrm{ds}}}^2+{i_{\mathrm{qs}}}^2)-K{\mathrm{\ω}}_e{L}_m\frac{{R_r}^2}{{\mathrm{\ω}}_{\mathrm{sl}}{L}_r}({i_{\mathrm{ds}}}^2+{i_{\mathrm{qs}}}^2)---\left(3\right)$

Wherein,

$K=\frac{{\mathrm{\ω}}_{\mathrm{sl}}{L}_m}{{R_r}^2+{{\mathrm{\ω}}_{\mathrm{sl}}}^2{L_r}^2}$

$L_{\mathrm{\σ}}=L_s-\frac{{L_m}^2}{L_r}$

According to formula (1) and formula (2), available slip expression formula is:

${\mathrm{\ω}}_{\mathrm{sl}}=\frac{R_r}{L_r}\·\frac{u_{\mathrm{ds}}{i}_{\mathrm{qs}}-u_{\mathrm{qs}}{i}_{\mathrm{ds}}+{\mathrm{\ω}}_e{L}_s({i_{\mathrm{ds}}}^2+{i_{\mathrm{qs}}}^2)}{u_{\mathrm{ds}}{i}_{\mathrm{ds}}+u_{\mathrm{qs}}{i}_{\mathrm{qs}}-R_s({i_{\mathrm{ds}}}^2+{i_{\mathrm{qs}}}^2)}---\left(4\right)$

According to formula (1) and formula (3), available slip expression formula is:

${\mathrm{\ω}}_{\mathrm{sl}}=-\frac{R_r}{L_r}\·\frac{u_{\mathrm{ds}}{i}_{\mathrm{ds}}+u_{\mathrm{qs}}{i}_{\mathrm{qs}}-R_s({i_{\mathrm{ds}}}^2+{i_{\mathrm{qs}}}^2)}{u_{\mathrm{ds}}{i}_{\mathrm{qs}}-u_{\mathrm{qs}}{i}_{\mathrm{ds}}+{\mathrm{\ω}}_e{L}_{\mathrm{\σ}}({i_{\mathrm{ds}}}^2+{i_{\mathrm{qs}}}^2)}---\left(5\right)$

According to relational expression (1), (2) and (3), available slip expression formula is:

${{\mathrm{\ω}}_{\mathrm{sl}}}^2=-\frac{{R_r}^2}{{L_r}^2}\·\frac{u_{\mathrm{ds}}{i}_{\mathrm{qs}}-u_{\mathrm{qs}}{i}_{\mathrm{ds}}+{\mathrm{\ω}}_e{L}_s({i_{\mathrm{ds}}}^2+{i_{\mathrm{qs}}}^2)}{u_{\mathrm{ds}}{i}_{\mathrm{qs}}-u_{\mathrm{qs}}{i}_{\mathrm{ds}}+{\mathrm{\ω}}_e{L}_{\mathrm{\σ}}({i_{\mathrm{ds}}}^2+{i_{\mathrm{qs}}}^2)}---\left(6\right)$

Namely

When motor is in low speed generating mode, because voltage is lower, so u _dsi _ds+ u _qsi _qs, u _dsi _qs-u _qsi _dsall less, when particularly adopting duty ratio and busbar voltage to estimate three phase terminals voltage, the voltage calculated has comparatively big error, thus makes u _dsi _ds+ u _qsi _qsand u _dsi _qs-u _qsi _dserror is comparatively large, and the molecule denominator of such slip expression formula (4) and slip expression formula (5) all can have larger error, and the slip precision that calculates may be caused poor.Slip expression formula only has u in (6) _dsi _qs-u _qsi _dseven if, u _dsi _qs-u _qsi _dshave certain error, after division arithmetic, error can be eliminated to a certain extent or be reduced, and so just can ensure the computational accuracy of slip.Therefore, adopt slip expression formula (6 ') to calculate the slip of squirrel cage asynchronous motor, the dependence to Electric Machine Control mode can be departed from, under various Electric Machine Control mode, slip is calculated exactly.

Second execution mode of the present invention relates to a kind of asynchronous machine slip method of estimation.Second execution mode is roughly the same with the first execution mode, main distinction part is: in the first embodiment, under synchronous rotating frame, estimates the slip of asynchronous machine, the dependence to Electric Machine Control mode can be departed from, under various Electric Machine Control mode, slip is calculated exactly.And in second embodiment of the invention, be under static two phase coordinate systems, estimate can depart from the slip of asynchronous machine the dependence to Electric Machine Control mode equally, calculate exactly slip under various Electric Machine Control mode.

Asynchronous machine slip method of estimation in present embodiment, idiographic flow as shown in Figure 2, comprises step 201 ~ 204, and wherein, step 201 ~ 203 are similar to step 101 ~ 103 in the first execution mode respectively, do not repeat them here.Only difference is introduced below:

Step 204: the information of voltage lower according to the steady-state equation of asynchronous machine, the parameter of acquisition, static two phase coordinate systems and current information, estimates slip.In present embodiment, still to carry out slip estimation to squirrel cage asynchronous motor, the slip obtained is

Asynchronous machine slip method of estimation in present embodiment has only carried out a Coordinate Conversion, fewer than the asynchronous machine slip method of estimation in a first execution mode step.

The step of various method divides above, just in order to be described clearly, can merge into a step or splitting some step, being decomposed into multiple step, when realizing as long as comprise identical logical relation, all in the protection range of this patent; To adding inessential amendment in algorithm or in flow process or introducing inessential design, but the core design not changing its algorithm and flow process is all in the protection range of this patent.

Third embodiment of the invention relates to a kind of asynchronous machine slip estimating system, as shown in Figure 3, comprises: parameter acquiring unit, information of voltage acquiring unit, current information acquiring unit, ordinate transform unit and slip estimation unit.

Parameter acquiring unit, for obtaining the parameter of asynchronous machine; These parameters comprise stator resistance, stator inductance, rotor resistance, mutual inductance between inductor rotor and stator rotor.Particularly, parameter acquiring unit can obtain above-mentioned parameter by the mode measured, or can obtain above-mentioned parameter by the mode self study of off-line identification.

Information of voltage acquiring unit, for obtaining the information of voltage of asynchronous machine.Particularly, information of voltage acquiring unit can be voltage sensor, and obtains information of voltage by sampling, or information of voltage acquiring unit can calculate information of voltage according to each phase duty ratio and busbar voltage; Wherein, information of voltage is three phase terminals information of voltage, wherein, can calculate three-phase phase voltage according to three phase terminals voltage.

Current information acquiring unit, for obtaining the current information of asynchronous machine.Particularly, current information acquiring unit can be current sensor, and obtains current information by sampling.

Ordinate transform unit, under being transformed into synchronous rotating frame respectively by information of voltage, current information.Particularly, under information of voltage, current information are first transformed into static two phase coordinate systems by ordinate transform unit respectively, then under the information of voltage under static two phase coordinate systems, current information are transformed into synchronous rotating frame respectively.

Slip estimation unit, for the information of voltage after the steady-state equation according to asynchronous machine, parameter, converted coordinate system and the current information after converted coordinate system, estimates slip.In the present embodiment, asynchronous machine is squirrel cage asynchronous motor; Under synchronous rotating frame, slip estimation is carried out to squirrel cage asynchronous motor, can obtain

Be not difficult to find, present embodiment is the system embodiment corresponding with the first execution mode, and present embodiment can be worked in coordination with the first execution mode and be implemented.The relevant technical details mentioned in first execution mode is still effective in the present embodiment, in order to reduce repetition, repeats no more here.Correspondingly, the relevant technical details mentioned in present embodiment also can be applicable in the first execution mode.

Four embodiment of the invention relates to a kind of asynchronous machine slip estimating system.4th execution mode is roughly the same with the 3rd execution mode, and main distinction part is: in the third embodiment, and ordinate transform unit, under synchronous rotating frame, estimates the slip of asynchronous machine.And in four embodiment of the invention, ordinate transform unit, under static two phase coordinate systems, estimates the slip of asynchronous machine.

Particularly, ordinate transform unit, under being transformed into static two phase coordinate systems respectively by information of voltage, current information.

Slip estimation unit, for the information of voltage under the steady-state equation according to asynchronous machine, parameter, static two phase coordinate systems and current information, estimates slip.Such as, under static two phase coordinate systems, slip estimation is carried out to squirrel cage asynchronous motor, can obtain

Because the second execution mode and present embodiment are mutually corresponding, therefore present embodiment can be worked in coordination with the second execution mode and be implemented.The relevant technical details mentioned in second execution mode is still effective in the present embodiment, and the technique effect that can reach in this second embodiment can realize in the present embodiment too, in order to reduce repetition, repeats no more here.Correspondingly, the relevant technical details mentioned in present embodiment also can be applicable in the second execution mode.

Persons of ordinary skill in the art may appreciate that the respective embodiments described above realize specific embodiments of the invention, and in actual applications, various change can be done to it in the form and details, and without departing from the spirit and scope of the present invention.

Claims (10)

1. an asynchronous machine slip method of estimation, is characterized in that, comprises following steps:

Obtain the parameter of described asynchronous machine; Described parameter comprises stator resistance, stator inductance, rotor resistance, mutual inductance between inductor rotor and stator rotor;

Obtain information of voltage and the current information of described asynchronous machine, and under described information of voltage, current information are transformed into static two phase coordinate systems or synchronous rotating frame respectively;

According to the information of voltage after the described parameter of the steady-state equation of described asynchronous machine, acquisition, converted coordinate system and the current information after converted coordinate system, estimate slip.

2. asynchronous machine slip method of estimation according to claim 1, is characterized in that, in the step of the parameter of the described asynchronous machine of described acquisition,

Described parameter is obtained by the mode measured; Or

Described parameter is obtained by the mode self study of off-line identification.

3. asynchronous machine slip method of estimation according to claim 1 and 2, is characterized in that, in the step of the information of voltage of the described asynchronous machine of described acquisition,

Described information of voltage is obtained by sampling; Or

Described information of voltage is calculated according to each phase duty ratio and busbar voltage; Wherein, described information of voltage is three phase terminals voltage.

4. asynchronous machine slip method of estimation according to claim 1 and 2, is characterized in that, in the step of the current information of the described asynchronous machine of described acquisition,

Described current information is obtained by sampling.

5. asynchronous machine slip method of estimation according to claim 1, is characterized in that, described information of voltage, current information is transformed into respectively in the step under synchronous rotating frame, comprises following sub-step described:

Under described information of voltage, current information are transformed into static two phase coordinate systems respectively;

Under information of voltage under static two phase coordinate systems, current information are transformed into synchronous rotating frame respectively.

6. asynchronous machine slip method of estimation according to claim 1, is characterized in that, if under described static two phase coordinate systems, carry out slip estimation to squirrel cage asynchronous motor, the slip drawn is

Wherein, ω _slfor slip, R _rfor rotor resistance, L _rfor inductor rotor, u _{α s}for stator α shaft voltage, u _{β s}for stator β shaft voltage, i _{α s}for stator α shaft current, i _{β s}for stator β shaft current, ω _efor synchronizing frequency, L _sfor stator inductance; And l _mfor the mutual inductance between stator rotor; Or,

If under described synchronous rotating frame, carry out slip estimation to squirrel cage asynchronous motor, the slip drawn is

Wherein, u _dsfor stator d shaft voltage, u _qsfor stator q shaft voltage, i _dsfor stator d shaft current, i _qsfor stator q shaft current.

7. an asynchronous machine slip estimating system, is characterized in that, comprises: parameter acquiring unit, information of voltage acquiring unit, current information acquiring unit, ordinate transform unit and slip estimation unit;

Described parameter acquiring unit, for obtaining the parameter of described asynchronous machine; Described parameter comprises stator resistance, stator inductance, rotor resistance, mutual inductance between inductor rotor and stator rotor;

Described information of voltage acquiring unit, for obtaining the information of voltage of described asynchronous machine;

Described current information acquiring unit, for obtaining the current information of described asynchronous machine;

Described ordinate transform unit, under being transformed into static two phase coordinate systems or synchronous rotating frame respectively by described information of voltage, described current information;

Described slip estimation unit, for the information of voltage after the steady-state equation according to described asynchronous machine, described parameter, converted coordinate system and the current information after converted coordinate system, estimates slip.

8. asynchronous machine slip estimating system according to claim 7, is characterized in that, described parameter acquiring unit obtains described parameter by the mode measured; Or

Described parameter acquiring unit obtains described parameter by the mode self study of off-line identification.

9. asynchronous machine slip estimating system according to claim 7, it is characterized in that, described ordinate transform unit, when described information of voltage, described current information are transformed under synchronous rotating frame respectively, under first described information of voltage, current information being transformed into static two phase coordinate systems respectively, then under the information of voltage under static two phase coordinate systems, current information are transformed into synchronous rotating frame respectively.

10. asynchronous machine slip estimating system according to claim 7, is characterized in that, described asynchronous machine is squirrel cage asynchronous motor;

Under described static two phase coordinate systems, described slip is

Wherein, R _rfor rotor resistance, L _rfor inductor rotor, u _{α s}for stator α shaft voltage, u _{β s}for stator β shaft voltage, i _{α s}for stator α shaft current, i _{β s}for stator β shaft current, ω _efor synchronizing frequency, L _sfor stator inductance; And l _mfor the mutual inductance between stator rotor; Or,

Under described synchronous rotating frame, described slip is

Wherein, u _dsfor stator d shaft voltage, u _qsfor stator q shaft voltage, i _dsfor stator d shaft current, i _qsfor stator q shaft current.