Indirect vector control with simplified rotor resistance adaptation for induction machines

A novel indirect vector control system for induction machines is proposed. To ensure accurate rotor flux orientation in face of severe thermal drift of the rotor resistance during practical operation, the system features a new rotor resistance adaptation method. The latter is based on the elimination of the q-axis rotor flux, which is calculated from steady-state relations of the induction machine. Compared with other rotor resistance adaptation methods found in the literature, for example, observer-based and model reference adaptive system-based methods, the proposed one poses much less computation burden and is quite convenient for online implementation. The basic principle and theoretical analysis are presented. The effects of other motor parameters on the adaptation method are also investigated. Based on the investigation results, a stator resistance compensation algorithm is incorporated to reduce the impact of incorrect stator resistance at low speeds. Some non-negligible issues in practical applications, such as dead-time effect and transport delay of digital pulse-width modulation process, are also investigated and taken care of. Simulation and experimental results show good dynamic and steady-state performance.