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US 6,636,013 B2Granted
Method of rapidly starting an asynchronous motor
AssigneeDiehl AKO Stiftung & Co. KG
InventorStefan Zeh
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AssigneeDiehl AKO Stiftung & Co. KG
InventorStefan Zeh
Estimating the term…
In order to accelerate an asynchronous motor with a squirrel-cage rotor even under load extremely quickly, and in particular within the time of an electromagnetic rotor time constant, in order to be able to cause it to start with a so-called kick start, while the rotor is not moving, quasi-stationary magnetic conditions are initially produced, like at the start of a synchronous motor with a permanent-magnetic rotor. For that purpose there is briefly produced a high-frequency rotor induction current which occurs electrically and spatially in a quasi-stationary condition when thereupon still within the rotor time constant, a strong unmoving stator magnetic field is produced, with a stator current vector which is displaced through about 90° for an optimum starting torque in relation to the rotor current vector, whereupon the stator rotary field starts with increasing amplitude and frequency.
A method for rapidly starting an asynchronous motor possessing a squirrel-cage rotor under load through an accelerated build-up of a motor torque by premagnetization, comprising impressing a magnetic field on a stator of the motor through a program-controlled inverter while the motor is at a standstill, said magnetic field changing over time so as to build up an induction current in the rotor, thereupon immediately impressing a stator current, said stator current having a spatial vector which is oriented substantially perpendicularly to a presently quasi-stationarily occurring vector of the rotor current, so as to finally, commencing with the beginning of a rotor motion, causing a stator rotary field to start at an increasing frequency and amplitude.
Dependencies are inferred from the claim text.