THE ANGULAR CHARACTERISTICS OF ASYNCHRONOUS MACHINES

摘要

Usually, the steady-state characteristics of alternating current machines, are in different modes analyzed: in terms of the slip concept (s)-for the asynchronous machines, or as a function of (θ)angle-for the synchronous machines with constant voltage (u_l=const.), respectively (ψ) angle for the synchronous machines with constant current (i_l=const). In reality, the both types of converters (asynchronous, synchronous)are characterized,in the stator frame,only by synchronous rotating magnetic fields, so a single type of converter exist: -the 'synchronous' converter, with a single type of fundamental characteristics-the angular(synchronous)characteristics. In this paper, starting from the general currents equation, respectively voltages equation, the angular characteristic m = f(θ) -for asynchronous machine with constant voltage, and m = f(ψ)-the torque characteristic at constant current are obtained; if the angle-slip, correspondence relation is utilized, the well known Kloss-formula is refunded. To compare the performances of the two machines is important to observe their maximum torques- m_(MA) for asynchronous, and m_(MS) for synchronous motor; the result is an advantage for asynchronous motor (generally, m_(MA)/m_(MS) > 1)for constant voltage fed, respectively an advantage for the synchronous motor(m_(MA)/m_(MS) < 1) with constant current.