DD269960A1 - METHOD FOR FIELD-ORIENTED MANAGEMENT OF ASYNCHRONOUS MACHINE BY RIVER DIFFERENTIAL METHOD - Google Patents

Abstract

The invention relates to a method for field-oriented management of an asynchronous machine according to the flow difference method by specifying the components of Ständerstromsollwerte via a setpoint computer in a vector of the rotor flux oriented coordinate system and control of these predetermined setpoints by a respective current component controller for the Laengs- and transverse components of Staenderstromes calculate the corresponding manipulated variables for the control of a decoupling network for the compensation of the stator voltage circuit of the asynchronous machine. In the method according to the invention, the maximum possible dynamics of the asynchronous machine are achieved. The influence of the non-linear magnetization characteristic and the temperature-dependent change in resistance in the rotor are taken into account. The command value calculator calculates, according to the invention, the current component nominal values, the slip frequency as well as the nominal value of the rotor flux vector from the desired engine torque and the stator voltage command value applied to the pulse inverter via the automatic control unit. A flow model calculates the actual value of the rotor flux vector via the rotor voltage equation in the coordinate system oriented on the vector of the rotor flux from the actual values of the current components and the mechanical rotor speed. The setpoint and actual values of the rotor flux vector are compared and from this an error vector is derived, which is fed to an adaptation mechanism for determining the adjustment of the parameter rotor time constant. This adjustment is applied both to the setpoint calculator and to the flow model. Fig. 1

Description

Title of the invention

Method for field-oriented guidance of an asynchronous machine using the flow difference method

Field of application of the invention

The invention relates to a method for field-oriented control of an asynchronous machine by the flow difference by setting the components of the stator current setpoints via a setpoint computer.

Characteristic of the known technical solutions

For controlling and regulating the asynchronous machine with squirrel-cage rotor, a large number of methods are known. The aim of most control and regulatory procedures is to take appropriate action ^! System decouple, so that a controller design with the methods of linear control theory is possible. The desired good dynamics of the control of the asynchronous machine further requires a point of the respective work point dependent and phasenriohtige leadership of the stator voltage or the stator current. A particularly simple and clear description of the loading / operating behavior of the asynchronous machine is obtained if all the currents, voltages and flows of the machine are related to a coordinate system revolving around the vector of the rotor flux linkage. (Method of field orientation).

The starting point for the control-technological treatment of the asynchronous machine is a fundamental wave model with the known simplifications:

lossless linear m & circle without magnetic preferential ring

2 6 9 9 i o

- Current-displacement rotor

- Acceptance of concentrated parameters

- sinusoidal input variables

The symmetry of the Masohines, in order to simplify the mathematical description of the machine, makes the introduction of complex vectors for current, voltage, and flux favorable. Thus, the mapping of the resulting string sizes as vectors in the complex plane is possible. The following equation system for describing the asynchronous machine can be specified in a coordinate system revolving around Wk »

(Equation of motion Momentegleiohung

Läuferflußverkettung

/ 3 /

Ständerflußverkettung

_r Lsh + Lm \ r / 4 /

Rotor equation (squirrel cage)

Stator voltage equation

According to two-branch theory, the transition from complex system equations to real equations can be made by splitting the vector equations into real and imaginary parts.

9 9 * 0

Simplifications and the design of the control structure is the choice of a suitable coordinate system to which all vectors are to be referred.

For the clearest description of the asynchronous machine one arrives duroh the introduction of a rotating coordinate system whose real axis coincides with the vector of Rotorflußverkettung. The vectors for current, voltage and flux are then equal in steady state. In this field-oriented coordinate system (d-q system), the flow-forming and moment-forming components of the stator vector i can be impressed separately. This is particularly advantageous from a control, economic point of view, since it succeeds in depicting the dynamics of the D.vehstromasynchronmasohine on iie a separately excited Gleichstromnebenschlußmaschine.

In the field-oriented coordinate system, the chip equations / 5 /> / 6 / go over

/ Τ /

/8th/

From equations / 2 / - / 4 / »/ 7 /» / Bf: the stator fluxing and the rotor current i can be eliminated. At the introduction of the component representation of the vectors

and observance of the Peld orientation, ie. the real axis of the field-oriented coordinate system agrees with χ during dynamic processes.

and the equations / 2 / - / 4 /, / 7 /, / 8 / can be summarized as the real equation of the asynohrone masohine:

- iss (i + / t> r4t _f ) ts tpKr ffef-tyLis Zs _9/10 /

In this case, ig, the field-forming and i designate the torque-forming component of the stator current vector i.

The essential task of torque and torque control of the asynchronous machine is to eliminate the mutual coupling of the state variables through pre-switched decoupling networks. For the design, the mathematical model of the machine is inverted. The outputs of the machine are used as model input values (set points) and the output signals of the model control the inputs of the machine.

In the asynchronous machine, two partial models are used for compensation: The first partial model is used: the decoupling of the stator circuit (decoupling network II -EK II-) and the second to compensate for the rotor circuit (decoupling network I). When feeding the asynchronous duroh an inverter with Ständerstromeinprägung the decoupling network II can be omitted, since then the voltage inputs of the asynchronous machine are not used and the stator voltage circuit is ineffective. The duroh the decoupling network I relationships to be achieved sioh duroh conversion of the equations of the rotor circuit. From the input variables

2699 4o

of the model torque value and flux setpoint, the desired values for the current components i _gd and i as well as the slip frequency co _{T are} reproduced dirokt. This corresponds to the principle of field-oriented control (eg the wing): "Speed control of regenerated Asynohronmasohlnen in controlling the flow through decoupling networks" Diss. TU Münohen 1981).

The complete compensation of the asynchronous machine succeeds only if the parameters of the decoupling networks coincide with the corresponding motor parameters and are carried out with variable motor parameters. The main advantage best.ht in the simplicity of the

> leadership. Apart from the mechanical rotor speed for determining the stator frequency for specifying the field orientation, no further measured values are required. Another possibility consists in the feedback of the state variables rotor flux and engine torque and use of a flux controller for specifying the setpoint value for the current component ig ^ _ao -iT and a torque controller for determining the setpoint value of the current component i _flaso ; Q · ^Da s corresponds to the method of field-oriented control (eg according to Ge.briel, R .: "Field-oriented control of an asynchronous machine with a microcomputer" diss. TU Braunschweig 1982)

 The main difficulty in the application of the regulated

C. Method consists of detecting the direct measurement i, a. inaccessible vector of the rotor flux for determining the actual values for the flux component and the engine torque and the specification of the stator frequency for maintaining the field orientation. The actual value calculation can only be carried out via models. In principle, it is possible to form a flux model based on the stator voltage equation or the rotor voltage equation. W: it's the model over

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the Rotorspänniingsgleiohung in the d-q-Kocrdinatenaystem because of the larger Betriebsbereiohes given at low speeds and at standstill Masohine preference. A disadvantage is the great dependence of the model transfer behavior on the temperature-dependent rotor time constant. To eliminate these; Disadvantageously, various adaptive measures for tracking the rotor time constant of the flux model are known. For example, the vector of the measured stator voltage is compared with the stator voltage vector derived from the flux model, and the resulting error signal is fed to an indentification controller, which acts on the reactor time constant of the flux model (according to Garces, Parameter Adaption for the Speed-Controlled Static AO Drive with A Squirrel-Cage induction engine "in IEEE Trans. IA 16 (1980) 2, pp. 173-178.) A considerable effort is required to calculate the error signal.

A very simple method is the method of correlation, in which additional time signals are continuously added to the d-axis of the stator current in order to determine possible couplings with the q-axis (according to Gabriel, R .: "field-oriented control of an asynchronous machine with a microcomputer" Diss. TU Braunschweig 1982), a disadvantage is the need for additional test signals that interfere with the operation. Weilerhin occur model error u.a. because of the frequency-dependent amplitude ratio and the frequency-dependent phase difference of the input and output variables of the model in the current and voltage detection and v / egen static and dynamic DC components in the output variables of the measuring elements. The above-mentioned difficulties mean that in highly dynamic drives major problems occur in the actual value calculation over the flux model.

From DE-OS 30 34 251 (H 02 P 5/40) alnd a method and Vorriohtung for determining the Läuferwiderstandea aaynohrone masohine known. Danaoh performs EMF and flux reconciliation by differentiation and calibration of measured current and voltage values. "Model parameter changes are reduced via internal control circuits.

It is known from DE-OS 31 44 188 (H 02 P 5/34) a flow determination device for the field-oriented control of a rotating field machine. A voltage and a current model for flux determination is proposed, between which it is switched depending on the operating point. A large part of the field-oriented regulations builds on this principle.

Aim of the invention ^!

The aim of the invention is to propose a method for field-oriented guidance of an asynchronous machine according to the differential plus method, which with justifiable outlay the maximum possible dynamics of the asynchronous machine with a low dependence on the magnetization Keunlinie and the rotor temperature.

Explanation of the essence of the invention

- The technical problem which is solved by the invention.

The invention is based on the object, the method for r-_doIentierten leadership of an asynchronous machine according to the Flußdifferanzverfahren duroh specification of the components of the Ständerstromsollwerte via a setpoint computer in an oriented to the vector of the rotor flux coordinate system and control of these predetermined setpoints by a respective current component controller for the longitudinal and

the lateral component of the stator current, which calculate the corresponding control variables for the control of a decoupling network to compensate for the stator voltage circuit of the asynchronous machine so that the influence of the non-linear magnetization characteristic e.g. be taken into account in the field weakening range as well as the temperature-dependent V / dererstandsänderungen in the rotor.

Features of the invention

According to the method of the invention, the command value calculator calculates from the engine torque command value and the stator voltage command value applied to the pulse inverter via a drive commutation the current component nominal values, the slip frequency and the target value of the rotor flux vector. The set point calculator calculates the setpoint values for the current components, the slip frequency and the rotor flux vector so that the control operates only in the linear operating range of the drive system and limitations by the inverter and the asynchronous machine with regard to the maximum possible stator voltage and the permissible stator current are not effective calculated using the rotor tension equation in the coordinate system oriented on the vector of the rotor flux, either from the actual values of the current components i _{S (} ji _s t »i) and the control signals U, 5 U in the flux synchronous coordinate system or the actual values of the current components i λ is + ^{un (} * ^ ^en control voltage signals ^ ₈ -JU _Λ in the stator fixed coordinate system and the mecha-

rotor speed is the actual value of the rotor flux vector. The actual value of the rotor flux vector is compared with its nominal value at a summation point, and an error vector is derived therefrom. The error vector is fed to an adaptation mechanism and this determines the adjustment of the parameter rotor time constant of

Control device of the asynchronous machine for adaptation to temporally or the operating state dependent change of the parameters of the asynchronous machine. The adjustment is supplied to both the setpoint calculator and the Fiußmodell. The parameter adjustment via the adoption mechanism works slowly with respect to the mechanical operations in the asynchronous machine so that disturbances in the electrical part of the drive system can be compensated by the current component controllers.

embodiment

The invention will be explained in more detail below using an exemplary embodiment. The accompanying drawings show:

Pig. 1: an arrangement according to the flux difference method with indirect stator angle formation from the Piußmodell

Pig. 2: an arrangement according to the plus / minus method with direct stator angle formation from actual speed value and slip frequency reference value

In a first embodiment of the invention, starting from a torque setpoint m,., And a Ständerspannungsistwert ü _, which makes the setting of the Plußsollwertes 3Γτ30 ^Ί 1 i ^{cal cal of} the linear control range via a Spannungsbegrenzungsregelkrels, in setpoint calculator 1, the flow and torque-forming components i _{a. (q ao} n ^{un <^} ^ _a naoll calculated following v / ground the Stromkomponentensollw6rte with Stromkomponentenistwerten compared to prior coordinate conversion in coordinate converter 9 of two or three phase currents in the rectangular current components ig ^ ig-f "- ^ s /? is ^ ^urc ^ vector / re / itfMj im

- ίο -

Vector rotator 10 are transformed in the Flußsynohronen coordinate system with the stator angle tf . . The control deviations of the stator current components R. -} R. are each the Strorakomponentenregler 2; passed 3 whose output variables y ^ and y are supplied to a decoupling network 4, also where the Flußsol value f _RE0 -n and di ^e mechanical '.'. angular velocity to the decoupling of the Stromkcmponenten "are used. the signals are then generated the control voltage components U" at the stator voltage vector U, which by means of vector rotation in the vector rotator 5 through the angular stator ifi a stator-fixed coordination '

tensystems as u , y. transferred and converted in a Ansteuerautomaten 6 to ignition signals for the DC link converter 7, which consists of input rectifier and fed with constant DC voltage pulse inverter for feeding an asynchronous machine.

To form the actual value vector of the rotor flux ytiti and the stator angle <iT in the flux model 11, the actual value components of the stator current vector i and the control components of the voltage vector u _a and the mechanisehe angular velocity to be used, wherein the stator current and stator voltage components either in the stator fixed coordinate system as i- _{Bc (} j _B ^ t ⁱ _{ö /} 3 i _s t and u, u- or in the flux-synchronous coordinate system can be present ^{as 1} SdISt ' ¹ SqISt ^{and u} sd' ^u s. "The di h Sikl ^ l id Kdit

q resulting stator angle φ1 is used for coordinate transformation in the vector rotors 5 and 10 and, if necessary, in the positive model 11 itself. The calculated actual value vector of the rotor flux Υ * _τ ^ _β ^ iat is subsequently guided to a summation part 12, with which the deviation, e, of the target value vector of the rotor flux lf ^ _rso nn formed in the nominal value calculator 11 is determined

- 11 -

Adctptionsmechanismus 13 determines the change of the temperature-dependent rotor time constant. The change signal for the rotor time constant Λ T is used to correct the rotor time constant used in the setpoint calculator 1 and can also be used to correct the model calculations in the flow model 11.

According to a further embodiment variant of FIG. 1, the stator angle τ / 1 for the coordinate transformation in the vector rotators 5 and 10 can be calculated from a summation point 14 of the slip frequency setpoint tJ formed in the setpoint calculator 1 and the mechanical velocity cj to the stator frequency (ύ _α and subsequent integration in the integrator 15 The required coordinate transformation ** in the flux model can then be realized by internal formation of a tearing angle. The buckle lower-level current component control in the field-oriented coordinate system leads to a fast and sensitive influencing of the motor torque of the voltage- injected inverter % xpeicm Compensates for disturbances in the electrical part of the drive system and improves the dynamics of reference variable changes and mismatches of the decoupling network. At a reasonable cost, the maximum possible dynamics is achieved. The influence of the non-linear magnetization characteristic, eg in the field weakening range, as well as the temperature-dependent change in resistance in the rotor are taken into account.

Claims (1)

claim Method for field-oriented guidance of an Ayyxi-ohronmasohine according to the Flußdifferenzverfahren duroh specification of the components of the S, tänderstromsollwerfce about a setpoint calculator in a <rji to the Vektoi? the rotor flux oriented coordinate system and control of these predetermined setpoints duroh ever a Stromkomponentenregl-ir for the longitudinal component of Ständerströmes and the transverse component of the stator current, which calculate the corresponding manipulated variables y ^ and y for driving einoe Entkopplungsnetawerkes to compensate the Ständerspannungskreisea the asynchronous machine daduroh characterized in that the set value converter (t) v_ from the Motormcmentsollwert (m_ - ^) and the PuIswoohselrichter (7) via a Ansteuerautomaten (6) applied Ständerspannungssoliwert the Stromhromponentensollwerte (i _adsoll } i _eqeoll ), the slip frequency ( O r ) and the setpoint of the rotor flux vector ίψ Q ₀ -II) calculated so that the controller only works in the linear operating range of the drive system and limits by the inverter (7) and the asynchronous machine (8) with respect to the maximum possible stator voltage and the permissible stator current not effective become, that a flow model (11) over the Rotorspannungsglei- f deviation in the vector of the rotor flux oriented coordinate system, either from the actual values of the current components (i _{d i} + j igai "+) ¹¹¹¹ ^ ^ ^s control voltage signals (u, j U) in flußsynchronen coordinate system or Actual values of the current components ^ saist * ¹ SAiSt) ¹¹¹¹ ^ ^{the s} ' ^fceuers P ^annun Sssignalen (U _s ^ ·, U _gß ) in the _stator-fixed coordinate system as well as the mechanical rotor speed (td!) D8n | actual value of the Eotorflußvektors (γ _rist ) calculated -F3- that the actual value of the rotor flux vector with its setpoint at a summation point (12) forgave and from an error vector (e) is derived, that the error vector is fed to a Adctptionsmeohanismus (13) and this from the adjustment ( j T _x ) of the parameter rotor time constant of the control device the asynchronous machine (8) for adaptation to Zeitlioh or the operating state dependent change of the parameters of the induction machine determines that the adjustment ( 4 ¹ ^ _x ) both the set value element (1) and the flow model (11) is supplied, that the parameter adjustment on the Adcfptionsmachanis- , mus (13) slowly compared to the mechanical operations in the asynchronous machine (8) works, so that disturbances in the electrical part of the drive system by the current component controller (2} 3) can be compensated. Lead Hierau X