| 摘要 |
A method for changing the speed of a motor group, in particular for starting or stopping it, the motor group comprising a plurality of squirrel-cage induction motors or synchronous motors and network converters arranged for their control, when the nominal supply power (P<SUB>ns</SUB>), the acceleration power (P<SUB>acct</SUB>) at the final speed (V<SUB>max</SUB>) of the motors and the losses (P<SUB>loss</SUB>) of the used power are known. On starting, the method comprises the steps of determining a first time instant (T<SUB>1</SUB>), when the motor input power corresponds to the nominal supply power, acceleration taking place at a predetermined acceleration rate (a<SUB>1</SUB>), accelerating the motors up to the first time instant (T<SUB>1</SUB>) substantially at the predetermined acceleration rate (a<SUB>1</SUB>), calculating a base value for the acceleration rate (a<SUB>2</SUB>) as a function of the speed (v) of the motors, at which acceleration rate the motor input power (P) corresponds to the nominal supply power (P<SUB>ns</SUB>), and accelerating the motors with varying acceleration rate (a<SUB>2</SUB>) after the first time instant (T<SUB>1</SUB>) so as to achieve the final speed (V<SUB>max</SUB>).
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