| The electric drive new energy vehicles emerge as the time required under the social background of the ecological environment pollution and the energy crisis of the fossil fuel. The hub motor drive mode eliminating the mechanical device can improve the transmission efficiency and reduce the manufacturing cost. The induction motor itself has the advantages of high reliability, maintenance free, low cost and good control performance, which make it the most promising mainstream for the electric vehicle in a large number of applications. The hub induction motor for electric vehicle use has not been reported, nor discussed in the literature about its design and optimization method. This paper try to study the electromagnetic design method and optimization parameters of the hub induction motor and give the practical application verification by an example of designing a low voltage drive hub induction motor with the outer rotor structure.This paper makes a comparison of different models of electromagnetic calculation. Combined with the special requirements of electric vehicle motor electromagnetic calculation, the time-harmonic finite element model of Flux FEA(finite element analysis) simulation software was used for the preliminary design and parameters optimization calculation, and the time-step model was used for the final verification and analysis.The electromagnetism calculation of the hub induction motor needs to know the stator phase voltage and frequency at different working conditions, and this is discussed in this paper by analyzing the torque characteristic of hub induction motor at peak output over the full speed range, which provide important reference for the motor electromagnetic calculation and evaluation.The research on the electromagnetic design of the hub induction motor for EV use is mainly focused on the main dimensions, the poles and the slot arrangement of the stator and rotor. Aiming at the weakness of low torque density, efficiency and torque insufficient at high speed for limited voltage, the paper discusses some of the most influential parameters, like the air gap magnetic density, the number of rotor slots and turns per phase of the stator winding. For low voltage drive motor increasing the rotor slot is a very effective method to improve the torque at high speed, and this has been applied for an invention patent.The outer rotor hub induction motor design example with the requirements of 72 V DC power supply, 500 N·m peak torque output, 750 r/min maximum speed, verified the hub induction motor electromagnetic design and parameter optimization method and the effectiveness and applicability of the time-harmonic finite element and the time-step finite element for hub induction electromagnetic design. |
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