Effect of stator resistance on average-value modeling of BLDC motor 120- degree inverter systems

For analysis and design of electromechanical systems with brushless dc motor drives, average-value modeling is often required. Many commonly used low-cost brushless dc motors operate with 120-degree inverter. The average-value modeling of such systems often ignores the commutation current and considers only the conduction interval. This paper uses a typical industrial BLDC machine to analyze the effect of stator resistance on the accuracy of a commonly used average-value model. It is shown that the model becomes less accurate for the motors with small stator resistance and significant commutation angle. However, reducing the electrical time constant of the stator winding increases the model accuracy in both time- and frequency-domains.