drehvektor - steueranordnung for the phase of standerstromvektors in about a mehrphasigen inverter fed drehfeldmaschine

摘要

1504605 Control of A.C. motors; inverting SIEMENS AG 1 Aug 1975 [3 April 1975] 32365/75 Addition to 1432268 Headings H2F and H2J In apparatus as described in parent Specification, for generating in a rotary field electrical machine an effective stator current vector which for a predetermined interval of time lies between two adjacent ones of discrete positions, the apparatus being controlled by a first signal generator for generating a first signal SZf and a second signal generator of higher frequency SZp, a comparator 8 and a changeover switch 6, 7 responsive to the instantaneous values of the first and second signals for switching the apparatus so as to produce said two discrete angular positions of the stator current vector. As described, the asynchronous motor 1 is controlled by an inverter having thyristors S1 . . . S6, diodes D1 . . . D6, and commutating capacitors C1 . . . C6. The inverter is controlled by D.C. from a rectifier GR. A voltage Un proportional to stator frequency is supplied to a threshold switch 5 which ensures that, when the stator frequency is above a predetermined value, the change over switches 4 are in the upper position so that a continuous sequence of pulses is supplied to the gates g1 . . . g6 of the thyristors S1 . . . S6. At low stator frequencies, change over switches 4 are in their lower positions and the gate pulses are sequentially changed by a set of change over switches 6 controlled by a threshold switch 7 in dependence on the sum or difference of a stator frequency sawtooth signal SZf and a higher frequency sawtooth signal SZp. This arranges that the stator vector continually oscillates about the effective position. Figs. 4, 5, 7 (not shown) relate to arrangements of integrators and threshold switches for generating the high and low-frequency sawteeth and includes two six-stage ring counters for deriving the sequential gate pulses A1 . . . A6 and B1 . . . B6, Fig. 8 show an alternative method of deriving the gate pulses by utilizing the sin and cos components of a continuously rotating preset control vector operating on threshold switches and gates. Figs. 10 . . . 12 (not shown) relate to combinations of gates and multipliers for deriving the stator frequency sawtooth voltage from the said preset control vector.