A relationship,between the duty cycle of PWM and angular velocity of DC motor,is derived from the classic DC motor model.Based on power conservation equation and the above model,a calculation method is proposed to get the internal resistance,the electromotive force constant,the motor viscous friction constant and the rotor torque constant.The parameters of a real motor,mounted a rotary-wing,are calculated through above method with input effective current,duty cycle and angular speed data.Finally,comparing the angular velocity obtained by the above mentioned model with test in the same duty cycle,the results show that the relative error is about 3％.%通过直流电动机模型推导出PWM波的占空比与电机转速的模型,根据功率守恒方程和上述模型得出电机内阻、反电动势、自身力矩系数和螺旋翼的升力系数的计算方法.通过试验的方法测试安装有螺旋翼电动机的输入电流有效值、占空比和转速,并计算电动机的参数,最后带入到占空比与电机转速的关系模型中,验证以上推导出的模型和计算方法的合理性.结果表明模型的相对误差在3％左右.
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