PWM变频器供电的感应电机传热特性

为了探究电动机在脉宽调(Pulse width modulation，PWM)变频器供电下的传热特性，近一步揭示变频参数（调制比）对电动机温升分 布的影响特征,以一台采用PWM变频器供电下55 kW驱动用感应电机为例，基于流体力学及传热学基本原理，结合电机通风结构特征，建立外部包裹有空气域的三维流热耦合求解域模型，并采用有限体积元法对电机内的温度场进行了数值研究。此外，针对PWM不同调制比控制条件下电动机全域内的传热特性进行了对比分析，结果表明：两个不同调制比控制条件下电机求解域 内各主要部件温升分布趋势大致相同；径向上，转子部分温升较高，在气隙位置温升出现阶跃式变化，定子部分温升较低；轴向上，电机各部分近风端温升较低，远风端温升较高；周向上，定子轭部温升呈波浪式变化。

Characteristics of Heat Transfer for Induction Motor Supplied by PWM Converter

In order to explore the characteristics of heat transfer for motors supplied by pulse width modulation (PWM)converter, and further reveal the influence characteristics of frequency converter parameters (modulation ratio) on the motor thermal distribution, a 55 kW induction motor supplied by PWM converter power is studied. Based on the computational fluid dynamics and the heat transfer theory, combined with the feature of motor ventilation structure, a three-dimensional flui d-thermal coupled model with motor encapsulated in air region is established. And the temperature field of asynchronous driving motor is simulated numerically by using the finite volume method. Therefore, characteristics of heat transfer for the whole motor domain are compared and analyzed under the control with two different modulation ratios. The motor temperature distribution trend is substantially the same in the solve region under the control with two different modulation ratios. In radial direction, rotor has the higher temperature. However, the curve of temperature-rise in the air gap has step-change and the lowest temperature-rise occurs in stator. In axial direction, the temperature-rise of each part of motor near the fan is lower, and that of each part of motor far away from the fan is higher. In circumferential direction, the curve of stator yoke temperature-rise has undulate change.