Gentle synchronization of two-speed synchronous motor with asynchronous starting

Abstract

The paper presents the results of synchronization calculations for a selected model of the GAe 1716/20t two-speed synchronous motor with switchable armature and field magnet windings, used for driving the main fans in deep mines. The calculations were performed using a specially developed (and validated by measurements) field-circuit model of the motor. The effect of the initial instant of synchronization on the latter's effectiveness and on dynamic process stabilization time was studied. It is shown that synchronization effectiveness can be increased through proper field current control in the synchronization initiation-synchronous speed interval. It is also shown that synchronization time can be reduced and the dynamic waveforms attenuated after the motor reaches the synchronous speed. The calculation results are presented in the form of diagrams.

Start-up of large-power synchronous motor with the 6 kV voltage source inverter and microprocessor-controlled unit for excitation supply

“…The machines with the appropriate structure (twospeed motors with switchable windings), can be startedup by changing the number of pole pairs [1,17]. Depending on the configuration of stator windings connection, there can be obtained a different number of pole pairs and different winding impedance which determines the inrush current.…”

“…Due to the weight of the fan rotor of up to a few dozen tons and a diameter of up to 9 m, this drive type is characterized by a high moment of inertia, which is about 10 times higher than the moment of inertia of the motor rotor [1]. The start-up of such a drive system is considered to be difficult due to the large power of the engine and a high moment of inertia.…”

Gentle synchronization of two-speed synchronous motor with asynchronous starting

“…A specially developed field-circuit model of the two-speed motor and Ansoft's Maxwell software were used to analyze the synchronization of the motor [11]. The transient module was used to calculate dynamic transient states.…”

“…Due to the fact that the number of magnetic poles is different from that of mechanical poles, the particular poles are in different magnetic conditions in a given instant ( Fig. 4) [3,11]. As a result, the contributions of the particular poles to the generation of driving torque are not equal [2].…”

“…To increase the pull-in torque, and thereby the effectiveness of synchronization, field current (often 50% higher than the rated current) forcing is commonly used [7,10]. But sometimes, even when field current forcing is employed, no effective synchronization is achieved [11]. The aim of this study is to show that in the adopted motor load conditions, synchronization effectiveness can be increased and the duration of transients reduced through the proper choice of the instant of starting synchronization and through field current control during this process, without using forcing.…”