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In-wheel direct-drive is the most efficient driving mode for electric vehicles, and it is the trend for applications in the future. In this paper, a novel variable-flux outer-rotor permanent magnet synchronous motor with a hybrid magnetic structure design is developed. Due to the hybrid magnetic pole with Nd-Fe-B and Al-Ni-Co permanent magnet(PM), the air-gap flux can be adjusted by changing the magnetization states of Al-Ni-Co PM, which is beneficial to realize a wide range of speeds and loads from the electromagnetic structure design. Firstly, basic structure features of the motor and the flux-adjusting principle are introduced. The design and calculation method of the PM dimensions is derived based on magnetic circuit analysis. Then the Preisach hysteresis model of Al-Ni-Co PM is described and is adopted to analyze the motor performance with the coupling of the time step finite element method(FEM), and the magnetization are investigated. Finally, the operational performance of the proposed motor is obtained by simulation, which verifies the design.

This paper introduces a submerged LNG (liquefied natural gas) pump cryogenic permanent magnet synchronous motor (PMSM). A 22kW/6000rpm prototype is designed for low temperature operation at −161°C. The influence of temperature on magnetic and electric parameters of materials is analyzed, and a coupled simulation model of electromagnetic-fluid-thermal-stress field is established. On this basis, the motor characteristics such as the loss, back EMF and torque are obtained. The accuracy of the simulation model is verified by the prototype test at −196°C liquid nitrogen. Simulation and test results show that the performance of the cryogenic PMSM is better than that of the traditional motor.

This paper introduces a Permanent Magnet (PM) synchronous torque motor with an external rotor. Firstly, the basic structural features of this motor are described. Novel spiral magnetic poles and axial-cooling structure is designed to increase the energy density and make the motor compact. The width, thickness and spiral angle of the poles are determined by magnetic computing, in order to ensure the wave of gap magnetic density is sine. To provide an effect cooling structure, the motor side hoods are designed as centrifugal fans to cool the coil down. Multiple air channels are cut in the stator core to increase the ventilation of air. The spiral poles can also constitute spiral air channels and produces wind to cool the magnets. It is possible to choose high electromagnetic load to gain high energy density based on a good cooling effect. Next, the method is determined and the program is compiled for electromagnetic computing. The finite element analysis on magnetic field is conducted by applying ANSYS. Finally, according to the optimization of the structure, a 3 kW prototype is fabricated. The no-load and load experiments are carried out to proof the performance of the motor.

This paper deals with the optimal design of permanent magnet synchronous motors (PMSMs). Firstly, the general rules and principles of motor optimization are summarized, and a field-circuit coupled optimal design method is presented based on combined selection of variable parameters, objective functions and constraint conditions. Then, choosing multiple structural dimensions as variables, parametric analysis is made to research the influence of structural design parameters on performance of the PMSM. On this basis, an optimal design for a two-pole line-start PMSM is made, which can successfully reduce the dosage of permanent magnet and improve the performance-price ratio.

Permanent magnet brushless motors for electric vehicles are presently given an increasing attention. With this trend, this paper deals with an interior permanent magnet (IPM) brushless DC motor (BLDCM), which is supposed to apply in a two-seater pure electric car. Firstly, the performance indicators of the motor were determined according to the power requirements of the car at different driving speed, and a 10kW IPM-BLDCM was designed preliminarily. Then, choosing air gap length, permanent magnet thickness and the number of stator winding turns as variables, parametric analysis was made to research the influence of structural parameters on system efficiency and the torque-current ratio. After an optimization design, a prototype was fabricated and tested. The test results show that the optimized prototype can meet the need of the driving system both in constant torque region and constant power region.

Vehicle retarders receive more and more attention along with its use growing. This paper introduces a new type of eddy current retarder with double-rotor excitation and liquid-cooled stator structure. It can be considered to consist of two retarder units combined in the radial direction. Four different double-rotor eddy current retarders were proposed, including a double electric excitation rotor, a double permanent magnet (PM) rotor and two kinds of PM and electric hybrid excitation rotor structures. Each retarder has its own advantages, and might replace some of existing products, with its improved braking capacities and better cooling performance. FE based analysis of the four retarders were carried out respectively, and their properties and operating effects were compared.

This paper introduces a two-pole three-phase high-power line-start permanent magnet synchronous motor (PMSM). First, the operating principle and structural features of the line-start PMSM are described. An interior PM rotor structure is presented, which adopts a radial-set of permanent magnets with multi-section for each pole. A motor model is then established by employing the finite element analysis software JMAG-Studio. The transient electromagnetic field is calculated and analyzed using the time-stepping FEM coupling with magnetic field analysis with electrical circuits. The starting process and steady-state performance are simulated, and the rationality of the motor design is validated.