High Torque Capability Research Articles

06/00302 Design optimisation of permanent magnet synchronous motors for high torque capability and low magnet volume: Vaez-Zadeh, S. and Ghasemi, A. R. Electric Power Systems Research, 2005, 74, (2), 307–313

06/00302 Design optimisation of permanent magnet synchronous motors for high torque capability and low magnet volume: Vaez-Zadeh, S. and Ghasemi, A. R. Electric Power Systems Research, 2005, 74, (2), 307–313

Influence of slot number and pole number in fault-tolerant brushless dc motors having unequal tooth widths

The electromagnetic performance of fault-tolerant three-phase permanent magnet brushless dc motors, in which the wound teeth are wider than the unwound teeth and their tooth tips span approximately one pole pitch and which have similar numbers of slots and poles, is investigated. It is shown that they have a more trapezoidal phase back-emf wave form, a higher torque capability, and a lower torque ripple than similar fault-tolerant machines with equal tooth widths. However, these benefits gradually diminish as the pole number is increased, due to the effect of interpole leakage flux.

Design optimization of permanent magnet synchronous motors for high torque capability and low magnet volume

Permanent magnet synchronous motors are being manufactured and used increasingly in low to medium power range applications due to their inherent advantages. There is a great deal of opportunity to enhance their merits by design optimization, thus reduce production costs and improve performance of the motors. In this paper a design optimization is performed on interior type permanent magnet synchronous motors to achieve high torque development capability with low permanent magnet consumption. A multi-objective optimization is performed in search for optimum magnet dimensions and location. The design optimization results in a motor structure superior to original motor specifications. Finite element method is used to evaluate the accuracy of the results.

An Analysis on Synchronous Reluctance Motors by Use of Magnetic Circuit.

The synchronous reluctance motors operated by a PWM inverter can be designed for the maximum saliency ratio (Ld/Lq). The saliency ratio is the most important parameter for achieving a high torque capability, high power factor and wide constant-power speed range. Generally, flux guides for the d-axis and flux barriers for the q-axis are provided to achieve a high Ld and low Lq, respectively, in order to maximize the saliency ratio. In this paper, the optimal shape and thickness of the flux barriers are investigated analytically. It is also demonstrated that the optimal rotor flux barrier shape can be expressed as the contour line of the function that shows the magnetic potential in a uniform material rotor. The effects of the magnetic resistance of the stator and the gap are also analyzed.

Analysis of Magnet Configurations for High Torque to Current Ratio in Surface Mounted Permanent Magnet Synchronous Motors.

Permanent magnet synchronous motors (PM motors) are used in many industrial applications as AC servo motors. Particularly surface mounted PM motors are most used in low power range. With recent developments of magnet materials, their high torque capability makes them suitable in middle power range.In this paper, different magnet configurations are presented to get high torque to current ratio, and then electro motive forces (EMF) are distorted by a non-sinusoidal flux density distribution. In this case, a sinusoidal current produces torque pulsations.To eliminate these pulsations, an adequate instantaneous current is computed. Consequently high torque to current ratio are obtained with adequate current.

Study of MOV operator and motor characteristics to determine torque capability

Motor operated valves (MOVs) used in the nuclear generating stations require the high torque capability of a motor when demanded during an accident scenario. This paper specifically deals with the behavior and classification of motors used in AC MOVs. This paper also deals with a methodology that may be consistently applied to determine the realistic capability (that is, rating) of the motor/operator. As an ongoing resolution to the NRC IEB 89-10 issue of the impact of degraded voltage condition and other environmental conditions on torque capability of the MOVs, the determination of appropriate motor torque capability is essential.

DSP-based control of brushless DC drives for direct-driven robotic arms

Modern permanent magnet brushless DC (BLDC) drives have excellent high-torque capabilities which make them suitable for direct-drive applications in robotic arms, but unfortunately they suffer from torque pulsations when controlled by a conventional current controller. The technique of instantaneous torque control with indirect torque sensing is aimed at reducing such torque pulsations. The AT&T DSP32, a digital signal processing chip, is used as the controller since the control algorithm requires high-speed computations. The DSP circuit has been constructed on a prototyping card and mounted in a microcomputer which serves as the program development system as well as run-time input-output controller. We present the design, implementation and experimental results of the proposed DSP-based instantaneous torque controller.

Strategy for the instantaneous torque control of permanent-magnet brushless DC drives

The paper describes an instantaneous torque control for a permanent magnet motor driven in a brushless direct current drive configuration. The motor has high torque capabilities, which makes it suitable for direct drive applications, but unfortunately it suffers from torque pulsations when controlled by a conventional sinusoidal current controller. Instantaneous torque control is aimed at eliminating such torque pulsation, thereby improving speed and position control. The approach adopted is to design an instantaneous torque control algorithm based on a variable structure strategy in the dq rotating reference frame. The switching commands for the inverter are generated by the digital controller directly. The required instantaneous torque feedback information is estimated from knowledge of the motor parameters and measurements of instantaneous currents and rotor position. The performance of the proposed controller design and torque feedback technique are investigated in computer simulation studies and experimental implementations. Experimental results for drive applications using instantaneous torque control and conventional sinusoidal current control are evaluated and compared.