| 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 (Pns), the acceleration power (Pacct) at the final speed (Vmax) of the motors and the losses (Ploss) of the used power are known. On starting, the method comprises the steps of determining a first time instant (T1), when the motor input power corresponds to the nominal supply power, acceleration taking place at a predetermined acceleration rate (a1), accelerating the motors up to the first time instant (T1) substantially at the predetermined acceleration rate (a1), calculating a base value for the acceleration rate (a2) 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 (Pns), and accelerating the motors with varying acceleration rate (a2) after the first time instant (T1) so as to achieve the final speed (Vmax).
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