Search

The influence of rotor configuration on sensorless control for interior permanent-magnet synchronous motors (IPMSM) with concentrated windings is evaluated. Sensorless control that gives estimated angle with simple integration procedure and the biased convergent point observer is applied. Two types of rotors are analyzed and their robustness for an offset value of the observer is compared. To analyze the influence of magnetic saturation, nonlinear motor voltage equation is solved. Finite-element analysis plays an important role to realize high-speed and precise analysis. Analyzed results show that the rotor which has salient poles on the side of permanent magnets is insensitive to the offset value of the observer. And the sensitivity to the offset value of the observer with these two types of rotors is confirmed by experimental results. Index Terms--Concentrated windings, finite-element method, interior permanent-magnet synchronous motors (IPMSM), magnetic saturation, sensorless control.

This paper proposes a variable-speed wind generation system using an interior permanent-magnet synchronous generator (IPMSG). The armature current vector of the IPMSG is optimally controlled according to the generator speed in order to maximize the generated power from the wind turbine. The IPMSG is controlled by the loss-minimization control with maximum power point tracking below the base speed, which corresponds to low and medium wind speed, and the maximum energy can be captured from the wind. Above the base speed corresponding to the high wind speed region, the current- and voltage-limited maximum output control is applied, where the current vector is optimally controlled so that the output may become the maximum in consideration of the constraints of current and voltage. The proposed output maximization control is achieved without mechanical sensors such as wind speed sensor and position sensor. The control system has been developed and several experimental results show the effectiveness of the proposed wind generation system. Index Terms--Interior permanent-magnet synchronous generator (IPMSG), maximum power point tracking (MPPT) control, sensorless control, variable-speed generation, wind generation.

An interior permanent-magnet synchronous motor (IPMSM) is a highly efficient motor and operates in a wide speed range; therefore, it is used in many industrial and home appliance applications. However, the torque ripple of synchronous motors such as the IPMSM and synchronous reluctance motor is very large. The variation of magnetic resistance between the flux barriers and teeth causes the torque ripple. In this paper, flux barriers are asymmetrically designed so that the relative positions between the outer edges of the flux barriers and the teeth do not correspond. As a result, torque ripple can be reduced dramatically. Index Terms--Asymmetric flux barrier, permanent-magnet synchronous motor, synchronous reluctance motor (SynRM).

Iron loss prediction is an important issue in both design and analysis of electrical machines. Because of their complicated structure, flux distribution, and rotational variation of flux, it is difficult to predict the iron loss in a machine exactly. This paper studies the iron loss in the core of rotating machines in which the rotational field is dominant, using the finite-element method. For electrical machines in practical operation, additional iron losses due to the appearance of rotation of flux vectors and harmonic flux densities make the calculation results deviate from the measured data. We have revised the method to account for these excess iron losses by considering both the influences of flux vector rotations and flux density harmonics. Calculation and experiments on two kinds of interior permanent-magnet synchronous motors have verified that our method produces results that agree well with the experimental ones. Index Terms--Electric machines and transformers, magnetic losses.

This paper proposes the current-sensorless drive system with only low-resolution position sensor in order to simplify the synchronous motor drive system. The high-performance current vector control can be achieved in the proposed drive system, where the current sensors are eliminated but the simulated currents based on motor model are used for current control. The low-resolution position sensor, which has a resolution of only 60 electrical degrees, is used instead of a conventional high-resolution position sensor, and the position information with higher resolution is estimated. The steady-state performance and dynamic performance are examined by several drive tests with respect to the interior permanent-magnet synchronous motor and the synchronous reluctance motor. The effectiveness of the proposed drive system is clarified from several experimental results. Index Terms--Current-sensorless drive, low-resolution position sensor, permanent-magnet synchronous motor (PMSM), synchronous reluctance motor (SynRM), vector control.

This paper presents a novel sensorless control strategy for a salient-pole permanent-magnet synchronous motor (PMSM). A new model of a salient-pole PMSM using an extended electromotive force (EMF) in the rotating reference frame is utilized to estimate both position and speed. The extended EMF is estimated by a least-order observer, and the estimation position error is obtained from the extended EMF. Both estimated position and speed are corrected so that the position error becomes zero. The proposed system is very simple and the design procedure is easy and clear. Several experimental drive tests are demonstrated and the experimental results show the effectiveness of the proposed sensorless control system. Index Terms--Extended electromotive force, interior permanent-magnet synchronous motor, observer, salient-pole permanent-magnet synchronous motor, sensorless control.

Permanent magnet linear synchronous motors have been developed for factory automation, transportation applications, and so on. In the rotary-type permanent magnet synchronous machines, the wide speed and constant power operation are realized by using the reluctance torque due to the saliency and the flux-weakening control. In this paper, we examine the effect of the interior permanent magnet arrangement for wide speed operation and the end effect in the linear structure. Index Terms - End effect, flux weakening, IPM-LSM, reluctance thrust.

Permanent magnet synchronous (PM) motors can be applied to applications requiring constant power operation, such as traction and spindle drives by means of flux-weakening control. In a PM motor drive system with flux-weakening control, the motor parameters are used to produce the current vector command. The motor parameters vary because of magnetic saturation and as a result, the control performances are affected by the magnetic saturation. In this paper, the effects of magnetic saturation are examined and the control system considering the magnetic saturation is proposed. The performances of the proposed control system are examined by simulations and the experimental results with respect to the prototype interior permanent magnet synchronous motor.

This paper aims to improve efficiency in permanent magnet synchronous (PM) motor drives. The controllable electrical loss which consists of the copper loss and the iron loss can be minimized by the optimal control of the armature current vector. The control algorithm of current vector minimizing the electrical loss is proposed and the optimal current vector can be decided according to the operating speed and the load conditions. The proposed control algorithm is applied to the experimental PM motor drive system, in which one digital signal processor is employed to execute the control algorithms, and several drive tests are carried out. The operating characteristics controlled by the loss minimization control algorithm are examined in detail by computer simulations and experimental results.

Interior permanent magnet synchronous motors can be applied to applications requiring wide-speed operation. The current vector control algorithm of an interior permanent magnet synchronous (IPM) motor for constant power operation over the base speed is proposed. As the available voltage controlling the armature current vector is small in the flux-weakening constant power region, the current vector sometimes becomes uncontrollable in transient operations because of the current regulator saturation. The high-performance current regulator is also proposed to improve the current responses in the flux-weakening region, which includes the decoupling current controller and the voltage command compensator. The control performances are confirmed by several drive tests with respect to the prototype IPM motor.

A new PWM strategy suitable for an inverter-fed induction motor is described. The output waveforms in the proposed PWM inverter are investigated both theoretically and experimentally. Although the output waveform is a non-sinusoidal waveform, the induction motor driven by the proposed modulating signal produces approximately constant torque. A modulating signal for the three-phase PWM inverter is obtained by superposing a rectangular wave on the specific trapezoidal wave whose flat portion is 120 degrees. By using the proposed modulating signal, the amplitude of the fundamental component is increased by about 17 percent more than that of a conventional sine wave inverter. The new system reduces the torque ripple as well as achieving the effective utilization of the DC supply voltage for the inverter.

The advantages of the conventional cylindrical linear pulse motor (C-LPM), which has a ring permanent magnet between the A- and B-phase stators, are its simple magnet shape and small motor diameter; the disadvantages are the thrust imbalance resulting from the magnetic flux path of the outer poles being longer than that of the inner poles. This thrust imbalance decreases the pull-in thrust and increases the positioning error. In this paper a new C-LPM with an interior permanent magnet mover which reduces this thrust imbalance is proposed. Steady and dynamic thrust are also examined and magnetic equivalent circuit is discussed. It is shown that a C-LPM with an interior permanent magnet mover effectively improves the thrust imbalance and the dynamic thrust.

This paper describes a current vector control method of permanent magnet synchronous motors (PM motors) for high torque operation. In this control method, the current phase angle is controlled according to load conditions in order to use the reluctance torque effectively. Several characteristics such as torque, efficiency, power capability and so on are greatly improved by this control on comparison with the conventional control method. The performance characteristics are greatly affected by the motor parameters which depend on the rotor configurations and permanent magnet geometries. The available maximum torque and power capability are also examined for the several types of PM motor considering the inverter capacity. The tendency toward magnetic saturation and demagnetization of permanent magnet are also examined.

Permanent magnet (PM) synchronous motors fed by PWM inverters are widely used for industrial applications. The PM motors sometimes have a saliency, in which the q-axis inductance is larger than the d-axis inductance. This paper describes a high-performance servo drive system of a salient-pole PM motor, in which an armature current vector is actively controlled according to load conditions in order to use a reluctance torque effectively, and as a result, a large torque can be produced. The control algorithm of the armature current vector is described, taking the demagnetization of PM and the magnetic saturation into account. The several characteristics such as torque, power factor, efficiency, power capability, transient responses, and so on are examined in detail by the computer simulations and experimental results.

This paper examines the design and the performances of a permanent-magnet assisted synchronous reluctance motor (PMASRM) for wide constant-power operation. The effects of properly adding magnets into the rotor of a synchronous reluctance motor are examined by several experimental results and analyses on the prototype machines. The proposed machine can offer a large constant-power speed range, high-efficiency and high-power-factor operation in comparison to the complete synchronous reluctance motor. It was shown that the problems such as the decrease of efficiency at light-loads and the uncontrolled generator mode operation, which occur in the high-speed flux-weakening operation of the conventional PM motor drives, can be eliminated in the PM-assisted synchronous reluctance motor. Index Terms--Constant-power operation, high efficiency, permanent-magnet-assisted synchronous reluctance motor, reluctance motor.