Electricity: motive power systems – Positional servo systems – With compensating features
Patent
1997-05-12
1998-09-15
Wysocki, Jonathan
Electricity: motive power systems
Positional servo systems
With compensating features
318807, 318623, H02P 700
Patent
active
058084371
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a method for the compensation of periodic shaking forces in an electrical rotating field machine or an AC-machine having a special winding for the combined generation of a torque and a transverse force in the same, wherein the transverse force F acts perpendicular to the rotor and its magnitude and direction can be set as desired, and wherein p.sub.1 and a control winding with the pole pair number p.sub.2 =p.sub.1 .+-.1, the drive current i.sub.s1 of the drive winding, p.sub.1 plane is determined, p.sub.2 plane necessary for a desired transverse force F* is determined in a coordinate system (T) rotating with the angle .gamma..sub.s.sup.(p1), coordinate rotation through the angle .rho..sup.(p.sbsp.2.sup.) =.rho..sub.0.sup.(p.sbsp.2.sup.) =.gamma..sub.s.sup.(p.sbsp.1.sup.) into a coordinate system (S) fixed relative to the stator, with any relative rotation of the control winding and of the drive winding in the stator being taken into account by the constant angle .rho..sub.0.sup.(p2).
2. Description of the Prior Art
A method for the independent control of the torque and of a transverse force F acting on the rotor in a rotary field machine with a p.sub.1 pole-paired winding and a (p.sub.2 =p.sub.1 .+-.1) pole-paired winding is described in the Swiss patent application No. 00 056/94-7. This control method takes account of all the transverse forces arising in an idealized machine (without taking account of the slot harmonics and the winding harmonics, of geometrical and electrical asymmetries in the flux circuit, of the anisotropy of the magnetic tension force, of the material saturation, and also of the imbalance forces acting on the rotor) and permits the precise control of the transverse force vector for each operating state of an idealized machine.
In the operation of a real machine, deviations arise as a result of the above named non-ideal characteristics of the machine between the desired transverse force and the real transverse force acting on the rotor. In particular, periodic shaking forces act on the rotor which have their origin in the above named non-ideal characteristics of the machine, which has proved disadvantageous with the control methods known hitherto.
SUMMARY OF THE INVENTION
It is thus the object of the invention to compensate for the deviations between the desired transverse force and the real transverse force acting on the rotor, in particular to compensate for the periodically occurring shaking forces, through additional control interventions and thus to avoid the disadvantages of the prior art.
The above named periodic shaking forces are compensated by a pre-control which acts on the desired force (at the input of the control method) or on the control current, and which is dependent on the flux, angle, on the mechanical rotor angle, on the angular velocity of the flux and on the mechanical angular velocity of the rotor. Moreover, linear and non-linear errors in the control of the transverse force vector such as arise from slot harmonics and winding harmonics and from the material saturation are compensated by a rotation stretching of the control current vector dependent on the flux vector.
Accordingly, periodic, and thus predictable, "disturbing forces" inherent to the system are compensated for by the superposition of corresponding magnetic forces acting in the opposite direction. The superimposing of the correction signal can take place at the force control input of the control current calculation block as a pre-control force, at the output of the current control computation block as a pre-control current in stator coordinates, or within the current control calculation block, prior to the rotational transformation, as a pre-control current in the coordinate system which rotates with the drive flux.
Since the periodic shaking forces can have various causes, a part of these shaking forces is periodically linked with the geometrical drive flux angle, and another part is periodically linked with the mecha
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Lust Antriebstechnik GmbH
Sulzer Electronics AG
Wysocki Jonathan
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