Yoji Takeda

Wide-speed operation of interior permanent magnet synchronous motors with high-performance current regulator

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. >

Sensorless control strategy for salient-pole PMSM based on extended EMF in rotating reference frame

This paper presents a novel sensorless control strategy for a salient-pole permanent magnet synchronous motor. A new model of 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 are 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.

Loss minimization control of permanent magnet synchronous motor drives

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 the 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. >

Sensorless output maximization control for variable-speed wind generation system using IPMSG

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.

Effects and Compensation of Magnetic Saturation in Flux-Weakening Controlled Permanent Magnet Synchronous Motor Drives

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

Mechanical Sensorless Drives of IPMSM With Online Parameter Identification

A mechanical sensorless drive system for an interior permanent-magnet synchronous motor, for which parameters including the inverter are identified, is proposed in this paper. The rotor position is estimated by a signal-injection sensorless scheme at standstill. The resistance, including the on-resistance of the insulated-gate bipolar transistor, the voltage error caused by the dead time of the inverter, and the d-axis and q-axis inductances are identified at standstill using the estimated position. After the motor starts by the signal-injection sensorless control, the sensorless scheme changes to a scheme based on the extended electromotive force estimation, which uses the identified parameters. The magnet flux linkage is also identified under the sensorless operation. The effectiveness of the proposed method is verified by several experimental results

Torque ripple improvement for synchronous reluctance motor using an asymmetric flux barrier arrangement

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.

Optimum control of IPMSG for wind generation system

This paper presents the optimum control of an interior permanent magnet synchronous generator (IPMSG) for a wind generation system. In order to maximize a generated power, IPMSG is controlled by a maximum power point tracking (MPPT) control and a maximum efficiency control. The torque of IPMSG is suitably controlled according to a generator speed and thus the power from a wind turbine settles down on the maximum power point by the proposed MPPT control without a wind speed detector. Moreover, using the maximum-efficiency control and the maximum-torque control, the losses of IPMSG are minimized and as a result the maximum generated power is obtained. Experimental results show the effectiveness of the proposed control method.

Motor design considerations and test results of an interior permanent magnet synchronous motor for electric vehicles

This paper describes the high performance motor design of an interior permanent magnet synchronous motor (IPM motor) for electric vehicles. The authors examined the differences in motor characteristics based on how the magnets were embedded. For this comparison, they set conditions so that the volume of magnets remained constant, and they used both computer simulation and experiments with a prototype motor. As a result, they were able to develop a double layer IPM synchronous motor, which has two layers of magnets embedded lengthwise in the radial direction in the rotor. The q-axis flux path can be expanded by using an IPM rotor with magnets divided into two layers with the separation lengthwise at the rotor radius. An evaluation of prototype motors confirmed that a double-layer IPM motor produces a 10 percent or more increase in the torque generated compared to a single-layer IPM motor using the same current. Also, the high efficiency operating region (min. 90%) was a minimum of 10% wider than the single layer IPM motor. However, reluctance torque of a double layer IPM motor with concentrated winding cannot be designed as high as that of a similar motor with distributed winding. This is because the inductance difference between the d and q-axes cannot be sufficiently increased in this former. Here, it was learned that a concentrated winding is inferior to a distributed winding both in terms of generated torque and the constant power region size.

Servo drive system and control characteristics of salient pole permanent magnet synchronous motor

Permanent magnet (PM) synchronous motors fed by PWM inverters are considered. PM motors sometimes have a saliency, in which the q-axis inductance is larger than the d-axis inductance. A high-performance servomotor drive system for a salient-pole PM motor is described. 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 for the armature current vector is described, taking the demagnetization of the PM and the magnetic saturation into account. Characteristics such as torque, power factor, efficiency, power capability, transient responses, etc. are examined in detail by computer simulations and experimentally. >