Siemens Aktiengesellschaft

Felix Blaschke

Leonhard Reng

Theodor Salzmann

Karl-Heinz Bayer

Herwig Klautschek

Walter Dreiseitl

Ingemar Neuffer

Guenter Schwesig

Karlheinz Bayer

Wolfgang Michel

In the field-oriented control of an asynchronous machine, the flux angle of which is calculated by a flux computer from the current and the voltage as the integral of the EMF, the correct flux vector must be available already at the start-up of the machine. For this purpose, one axis (M.phi.1) of a model coordinate system as well as the components (iO*, iM*=0), referred to the model coordinate system, of a vector parallel to this axis is determined at an input device (E1, E2) by a constant, given starting angle (.phi.MO*). This vector is transformed by means of the field angle (.phi.s) calculated by the flux computer for forming the converter control variables into the stator coordinate system while the machine is excited but standing still. The angle deviation (.phi.MO*-.phi.s) of the calculated field angle from the starting angle is used by a controller (CR) for correcting the calculated field angle. Before the setting device switches to the operationally provided reference value transmitter (RV), the calculated filed angle (.phi.s) therefore assumes the starting angle (.phi.MO*) and the control device forces via the converter a stator current and machine flux parallel thereto. At the same time, also the parameter of the stator resistance used for calculating the flux can be adjusted.

Method and apparatus for operating a field-oriented rotating-field

To assure the commutatibility of an intermediate circuit converter with an impressed intermediate circuit d.c. current it is sufficient to limit the rate of rise of the intermediate circuit current under operating conditions to the product f*. i* from the current and frequency of the converter. A rate of rise limited in such a fashion to a maximum value reflecting operating conditions can be preset to a rate of change limiter using a rate of rise limiting controller to which the preset maximum value as well as the rate of rise of the control value for the intermediate circuit current itself has been preset. For that purpose a current controller, whose output signal are connected to suitable control values, assures an immediate control of the intermediate circuit current to the current reference value which has been limited in its rate of rise.

Method and apparatus to operate an intermediate circuit converter with

An engine or a similar torque generator with internal torque M1 and moment of inertia T1 and an electrical drive with electrical torque M2 and moment of inertia T2 coupled thereto interchange an interchange torque MA over a coupling according to the equation M1=(MA) (1+(5 T)).sup.2 (1.sup.2 +(T1/T2))-M2,(T1/T2). Based on the actual values MA and M2 as well as a parameter (T1/T2)* and a model time constant T*, a model value M* is computed in accordance with this function, which indicates the actual internal torque if said parameters correspond to the actual parameters. Thus, using supplemental set values .DELTA.M2 the preset electrical torque is varied and the parameters calibrated in such a manner that the effect of the M2 variation on the model value virtually disappears.

Method and apparatus for determining the torque of a torque generator

In order to determine from a reference vector (for instance from the EMF vector e.sub.s of a rotating field machine given by the current i.sub.s and the voltage u.sub.s) a model vector by integration (for instance the flux vector) and to thereby suppress defects of technical integrators and instabilities of the circuit used, a correction vector is formed which is rotated relative to the model vector (angle .epsilon..sub..phi.) and of which the magnitude is proportional to the derivative of the vector magnitude, or proportional to another volatile quantity. The model vector itself is obtained by integration of the sum vector formed by the reference vector and correction vector. This 'voltage model' can optionally be controlled by a reference vector.

Method and apparatus for stabilizing the locus of a vector formed by

For determining the flux vector, an EMF vector (e.sub.s) is formed in an EMF detector (15) from the stator current and the stator voltage, the components of which are determined in a rotating coordinate system rotated by an angle (.beta.) relative to the coordinate system which is fixed with respect to the stator. The flux vector (.psi..sub..beta.) is formed in the rotating coordinate system, taking into consideration the rotary EMF component (e.sub..beta..sup.R) which is generated from the flux vector through rotation by .pi./2 and multiplication by the frequency of rotation (.beta.). The angle of rotation (.beta.) is determined by feeding the direction deviation of the flux vector (.psi..sub..beta.) or a reference vector (.psi.*) for the flux vector by the angle (.beta.) to a servo control (27 or 30, respectively), the output signal of which is fed as the speed of rotation (.beta.) via an integrator (20) for forming the angle of rotation (.beta.).

Method and apparatus for determining the flux vector of a rotating field

An EMF detector supplies, from the voltage and the current, the EMF vector in a coordinate system fixed in space, the integral of which is the flux vector. The integration is carried out in the field oriented coordinate system, in which the EMF vector is transformed by means of a vector rotator. A rotational component is taken into consideration in the integration by having a first integrator form, from the field parallel EMF component, the magnitude of the flux and having a divider form, from the second EMF component and the magnitude of the flux, the flux frequency, from which frequency an integrator forms simultaneously the flux angle and the angle of rotation for the vector rotator. An angle control input characterizing the steady state and the angle of rotation, through an angle servo control selectably furnishes the field frequency entered into the second integrator to form, from a magnitude servo control, a feedback signal added to the field parallel EMF component. Further provided are circuits for taking into account the stray inductance without differentiation and a circuit for stabilization and damping.

Method and apparatus for determining the flux vector of a rotating-field

Apparatus for controlling a salient-pole machine includes a stator current control element to make the stator current i.sup.S follow preset desired values i.sub..phi..sup.S*. A field current control element develops from preset desired flux values .psi.*, from the flux signal output of a flux computer (direction .phi..sub.L) and from an inductance parameter (the shunt inductance X.sub.q of the machine) a fictitious field current value signal i.sub.O.sup.E*, which represents the field current value which would be used to control a hypothetical nonsalient-pole machine. This signal i.sub.O.sup.E* is modified by a correction factor derived from the product of the longitudinal component of the flux .psi..sub.d (from the flux computer) and the different between the reciprocals ((1/X.sub.q)-(1/X.sub.d)) of the shunt and series inductances of the machine, to give a field current control signal that accounts for the asymmetry of the salient-pole machine.

Apparatus for the control of a salient-pole machine

Disclosed is an apparatus for operating a converted-fed asynchronous electric motor which comprises a flux computer for determining the position of the flux vector from the input values for the stator voltage provided by said motor by solving all the electrical quantities of the Park equations describing said motor in a given position of the rotor axis, taking into account the parameter values corresponding to the rotor resistance and the stator resistance of said motor whereby signals corresponding to the position of the flux vector and belonging to a solution, can be tapped from said flux computer; a converter control unit coupled to said flux computer and said convertor rectifier respectively, forming the control quantities for driving the converter rectifier from the determined position of the flux vector and from the nominal input values which fix the components of the stator current vector parallel and perpendicular to the flux vector.

Device for the field-oriented operation of a converter-fed asynchronous

Disclosed is a method to detect the rotor resistance of an asynchronous machine, wherein a first vector attached to the emf of the machine is determined by computing the emf-vector or the flux vector from the stator voltages and the stator currents; wherein a flux attached to an arithmetic model circuit is determined, whereas the arithmetic model circuit uses the stator currents and the rotor position of the machine and an adjustable model parameter for the rotor resistance as basic quantities and imitates the dynamic events leading to the magnetic flux of the machine; wherein a difference of two quantities is determined, wherein the first quantity represents a defining quantity of the first vector attached to the machine and the second quantity represents a respective defining quantity of a second vector derivable from the imitated flux and that the setting of a model parameter is varied until the value of the difference is a minimum, whereas the model parameter corresponding to the minimum of the difference is regarded as the resulting rotor resistance of the machine.

Method and apparatus for determining the rotor resistance of an

Apparatus is disclosed wherein parameter values for the stator resistance, the main inductance and the stray inductance of an asynchronous machine is detected without using information about the rotor position. Thereby the apparatus consists of an EMF-forming circuit, an arithmetic control circuit, an arithmetic model circuit, and a control circuit. All circuits are coupled to form an overall model circuit designed according to a closed loop circuit to simulate the operational conditions of an asynchronous machine. In a balanced position of the control circuit the output signals of the control circuit represent the actual parameter values to be determined.

Device for determining the parameter values for stator resistance,

In a rotating machine converter controlled drive, the EMF vector components formed from the stator current and stator voltage are integrated by means of a-c voltage integrators, the output quantities of which establish the components of the machine flux vector. In the converter control the parallel and normal components of the stator current relative to this flux vector are introduced. The a-c voltage integrators include zero controllers in a feedback circuit, into which the difference between the machine flux components and corresponding model flux components are introduced. The model flux components are calculated in a computing model circuit from the stator current, magnetization current and rotor position.

Rotating field machine drive

A control unit for regulating an asynchronous motor supplied with power from a three phase network by a line-controlled power converter which is DC coupled to a self-commutated inverter has a function generator and a current regulator which controls the stator current of the motor by the controlling rectifier valves in the inverter. Control of the stator current is a function of a predeterminable value of flux fed into the function generator. In a parallel control system, an actual-value computer and a load state control regulate the stator frequency by generating a signal for controlling the self-commutating converter as a function of the actual values of the stator current, the stator voltage, and a value calculated from the function generator input variable. The computer forms signals corresponding to the amplitude of the flux vector, and to a stator current component perpendicular to the flux vector. A variable derived from the predeterminable variable is applied to the load state control as a reference value. Fall-out-proof, low oscillation, speed control is effected from low angles to nearly 90.degree..

Load state control for an asynchronous machine fed by a converter

For forming ##EQU1## in a pulse width multiplier, two input voltages b.sub.i are summed at the input of an inverter and are added, after each passes through a separate switch and proportional stage, at the input of a smoothing stage, to the inverter output signal. The switches are actuated by switching pulses which are width-modulated in accordance with the factors c.sub.i. The calculated sum is present at the output of the smoothing stage. Great accuracy in field-oriented control of rotating-field machines is possible when vector analyzers and vector rotators designed in this manner are used.

Multiple pulse-width multiplier

A coordinate converter useful for field-oriented control of a rotating-field machine includes a divider, a first adder, a multiplier and a second adder by which the magnitude of the vector and the tangent of the half-angle relative to one axis can be determined. An ancillary unit forms an angle-proportional variable from the half-angle tangent. A rotating vector can also be processed.

Converter for changing Cartesian vector variables into polar vector

A coordinate converter distinguished by low cost of hardware and useful for the field-oriented control of a rotating-field machine contains two multipliers, an adder and a subtraction element in a logic circuit. Optionally, two proportional elements can be added thereto. With this coordinate converter, the two Cartesian coordinates can be determined. If the magnitude is constant, the coordinate converter can be used as a sine-cosine generator. In addition, a supplemental circuit for generating a rotating vector is described.

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Erlangen, Germany

Felix Blaschke