Electronic Pole-changing Control Strategies Of Five-phase Induction Motor

With the development of power electronics technology and computer control technology, The research on multiphase motor system has been promoted further. Compared with the traditional three-phase motor drive system, multiphase motor drive system has many advantages such as the capability of high power, high reliability, multiple control freedoms, etc. Because of these advantages, multi-phase motor drive system is suitable for high-power transmission industrial applications, especially naval propulsion, aerospace and other fields. Multiphase systems have many similarities with three-phase system in terms of principle, but as a new technology, there are still some problems in control theory and practical applications which are worthy to be studied and perfected.On the basis of the theoretical analysis of the multiphase motors, Electronic pole-changing control strategies of five-phase induction motor are highlighted in this paper.First of all, the winding function theory is introduced. Based on it, the structure of the multiphase induction motor windings is analyzed. Using space vector decoupling theory, the mathematical model of multi-phase induction motor is built and a multiphase induction motor can be decoupled into multiple orthogonal planes to control. Multiple control freedoms of the multiphase motor control system are analyzed and its applications are briefly introduced, laying the mathematical and theoretical foundation for future research.Dual-plane vector control principle of five-phase induction motor is introduced in detail. Based on it, the electronic pole-changing strategies of five-phase induction motor are analyzed. Since the torque ripple is large in step response pole-changing, ramp response and exponential response pole-changing control methods are proposed. Taking the five-phase induction motor as object, the control strategy is verified on a multiphase variable-speed drive system.According to the principle of Sliding Mode Variable Structure Control (SMC) theory, a current control strategy is derived. The variable structure current control strategy and traditional PI current control strategy are compared. The variable structure current control strategy is adopted in the electronic pole-changing research of ramp response and experimental results prove this current control strategy can reduce torque and speed fluctuations in the transition.Speed sensorless vector control technology of five-phase induction motor is researched. Two speed identification methods based on model reference adaptive (MARS) control and SMC are described. The speed convergence rate is derived based on Popov super stability theory. By using MATLAB software, these two speed identification methods are simulated and analyzed. Finally, the SMC speed identification is experimentally verified.