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In this paper a stiffening technique for cage rotors of induction machines is proposed and analyzed, aimed at reducing the mechanical oscillations excited by the traction torque harmonics. The solution is simple, consisting of stiffening blocks inserted between couples of adjacent copper bars, overhanging from the rotor stack. The insertion of the stiffening blocks yields an increase of the lowest...
Harmonic analysis of a network of Adjustable Speed Drives (ASDs) has been experimentally investigated. A small-scale laboratory of the network of two ASDs connected to two induction motors was setup. Load of motor 1 was fixed while load of motor 2 was varied. In the experiment, measurements have been done at both side of power transformer to analyze power system harmonic.
In this paper, an axial-radial flux compound-structure permanent-magnet synchronous machine (CSPMSM) which consists of one axial-flux PMSM and one radial-flux PMSM is investigated. The purpose of this kind of machine is to keep the internal combustion engine (ICE) operating at maximum efficiency by harmonizing its two machines during all driving cycles in hybrid electric vehicle (HEV), and therewith...
This paper proposes a novel control method that uses current harmonics to minimize torque ripple for permanent magnet synchronous motor (PMSM) applied to electric power steering (EPS) system. In the EPS system, PMSM is accompanied by magnetic saturation of iron core due to high power and limited space. Partial magnetic saturation in the stator teeth results in significant torque ripple. In order to...
PWM technology has been widely used in motor drive systems today. To avoid the short-circuit condition, dead-time must be inserted to the PWM driving pulses. The addition of dead-time increases the harmonic of output voltage, makes the waveform of winding current more badly. The ripple of motor torque and speed is also increased by the addition of dead-time. The influence of dead-time is more remarkable...
The dual three-phase induction motors can eliminate the pulsing torque of 6 times the fundamental frequency. In order to acquire more improvement, the lowest pulsing frequency should be increased further while the magnitude decreased. Torque pulsation is caused by the harmonic currents of order 6nplusmn1 (n=2, 4......). So the key to eliminating the pulsation is reducing the substantial harmonics...
This paper presents the result of the two-dimensional finite element analysis on the effects of rotor pole arc variation and number of teeth per rotor pole with different teeth depths and stator excitation pattern on various performance parameters like cogging torque, developed torque, harmonic torques, torque ripple and phase inductance for an 6/8, three phase flux reversal motor. A novel excitation...
Permanent magnet machines with windings concentrated around each tooth gain more and more importance. In this paper, the magnetomotive force of a three-phase winding with concentrated coils will be analysed. As an example, a machine with a two-coil zone width with opposing flux is regarded. It will be shown that there are two different winding alternatives with four different rotor pole numbers that...
Rotor structures of interior permanent magnet motors are investigated in order to reduce harmonic iron losses at high rotational speeds under field-weakening control. First, an optimization method combined with an adaptive finite element method is applied to automatically determine the shapes of the magnets and rotor core. The optimized motor is manufactured to verify the validity of the calculation...
The implementation of concentrated windings in interior permanent magnet (IPM) machines has numerous advantages over distributed windings, with the disadvantage being mainly the decrease in saliency ratio. This paper presents a proposed finite element (FE) method in which the d- and q-axis inductances (Ld and Lq) of the IPM machine with fractional-slot concentrated windings can be accurately determined...
This paper presents the improvement of dynamic characteristics in interior permanent magnet (IPM) type BLDC motor with notch. The notch is applied on the surface of the rotor to reduce the cogging torque and to improve dynamic characteristics. The current, inductance and torque of initial model and optimal model are analyzed by FEA. The validity of improved dynamic characteristics is confirmed.
The general methods of analysis and study for multi-phase permanent magnet synchronous motor (PMSM) variety speed system based on the vector space decomposition theory are discussed in this paper. Furthermore, the reliability of the system is discussed and a fault-tolerant compensation strategy purposed forming the revolving magnetic field in order to solve the system occurred familiar faults is also...
This paper presents a new equivalent circuit for the brushless doubly-fed machine (BDFM) which is suitable for the steady state studies of the machine and the BDFM for adjustable speed drive systems. Based on the fundamental equivalent circuit for the BDFM and the chain equivalent circuit, the new equivalent circuit is developed for the investigation of the BDFM harmonic influence. Simulation results...
In order to reduce the cogging torque, many methods have been advised and studied in permanent magnet(PM) motor. In this paper, the methods of pole arc coefficient of PM, armature teeth notching, PM shifting and different pole arc coefficient combination are studied and improved based on the analytical expression of cogging torque derived in this paper, and the methods to decide the design parameters...
Compared with their three-phase counterparts, multiphase machines with phase number n ges 5 have many advantages like lower torque pulsation, higher power density, better fault tolerance, etc. Due to these advantages and the increasing demands on high performance and high power adjustable speed drives, the research on multiphase drives has experienced a significant growth since the end of last century...
The work analyses the universal motor, developing its transient model, where the parameters are derived from the design data; the model takes into account saturation effects and core losses and allows to analyse the performances and waveforms at the load side (torque, speed) and at the terminals (voltage, current). Since the motor is used in low cost household appliances, the power control is often...
Stator current spectral analysis techniques are usually used to detect rotational faults in induction motors. However, position-varying load torque oscillation at multiples of the rotational speed has exactly the same effect. Harmonics resulting from the load torque oscillation often obscure or even overwhelm the detection of rotor faults since the magnitudes of a load torque oscillation induced harmonics...
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