The common analytical models for the no-load iron loss of permanent magnet(PM)motors usually neglect the iron loss caused by the rotating magnetic field in the tooth tips and the harmonics of the magnetic fields in th...The common analytical models for the no-load iron loss of permanent magnet(PM)motors usually neglect the iron loss caused by the rotating magnetic field in the tooth tips and the harmonics of the magnetic fields in the teeth and yokes.This paper presents an analytical model for no-load iron loss of a fractional-slot surface-mounted permanent magnet motor.According to the existing analytical model of the magnetic field distribution in the slotted air gap,the magnetic flux densities considering the harmonics of the stator tooth and yoke are both derived based on the continuity of magnetic flux.Due to the complexity of the magnetic field in the tooth tip,the tangential flux density of the tooth tip is approximated by an equivalent sine wave and the radial component is regarded to be the same as that of the corresponding tooth.After obtaining the magnetic fields in stator different regions,the analytical iron loss is calculated by using the Bertotti model and the orthogonal decomposition model.A 20-pole/24-slot PM synchronous motor is taken as an example.The maximum error between the analytical model and finite element model(FEM)is 5.46%,which verifies the validity of the proposed method.展开更多
Because the mover and stator of a doubly-fed linear motor are both equipped with three-phase windings, the motor enables contactless energy to be transferred from the stator to the mover. Thus, when a doubly-fed linea...Because the mover and stator of a doubly-fed linear motor are both equipped with three-phase windings, the motor enables contactless energy to be transferred from the stator to the mover. Thus, when a doubly-fed linear motor is used in the linear driving system of trains, neither an overhead line nor a third rail is needed. However, the doubly- fed motor will lead to more severe thrust fluctuation than the unilateral motors. In order to overcome this shortcoming, the thrust fluctuation of the doubly-fed motor should be analyzed. In this paper, an expression for motor thrust is derived. It points out that the slot effect caused by the slotted structure is the main reason for the increase of thrust fluctuation. The method of adopting unequal pole pitch and unequal slot numbers per pole per phase of stator and mover, is proposed to weaken the slot effect when designing the motor slot parameters. Three different motor models are simulated by ANSOFT. The proposed method results in a motor thrust fluctuation coefficient of 8.4%, compared to 49.4% for the conventional method. Therefore, the motor's thrust fluctuation is effectively suppressed by the proposed method.展开更多
基金Supported by the Major Science and Technology Project Servo Drive and Motor Test Specification and Standard Research and Test Platform(2012ZX04001051).
文摘The common analytical models for the no-load iron loss of permanent magnet(PM)motors usually neglect the iron loss caused by the rotating magnetic field in the tooth tips and the harmonics of the magnetic fields in the teeth and yokes.This paper presents an analytical model for no-load iron loss of a fractional-slot surface-mounted permanent magnet motor.According to the existing analytical model of the magnetic field distribution in the slotted air gap,the magnetic flux densities considering the harmonics of the stator tooth and yoke are both derived based on the continuity of magnetic flux.Due to the complexity of the magnetic field in the tooth tip,the tangential flux density of the tooth tip is approximated by an equivalent sine wave and the radial component is regarded to be the same as that of the corresponding tooth.After obtaining the magnetic fields in stator different regions,the analytical iron loss is calculated by using the Bertotti model and the orthogonal decomposition model.A 20-pole/24-slot PM synchronous motor is taken as an example.The maximum error between the analytical model and finite element model(FEM)is 5.46%,which verifies the validity of the proposed method.
文摘Because the mover and stator of a doubly-fed linear motor are both equipped with three-phase windings, the motor enables contactless energy to be transferred from the stator to the mover. Thus, when a doubly-fed linear motor is used in the linear driving system of trains, neither an overhead line nor a third rail is needed. However, the doubly- fed motor will lead to more severe thrust fluctuation than the unilateral motors. In order to overcome this shortcoming, the thrust fluctuation of the doubly-fed motor should be analyzed. In this paper, an expression for motor thrust is derived. It points out that the slot effect caused by the slotted structure is the main reason for the increase of thrust fluctuation. The method of adopting unequal pole pitch and unequal slot numbers per pole per phase of stator and mover, is proposed to weaken the slot effect when designing the motor slot parameters. Three different motor models are simulated by ANSOFT. The proposed method results in a motor thrust fluctuation coefficient of 8.4%, compared to 49.4% for the conventional method. Therefore, the motor's thrust fluctuation is effectively suppressed by the proposed method.