Observability Analysis of Q-MRAS Drive of Induction Motor With and Without Virtual Voltage Injection

Induction motor sensorless control drive is a hot topic in Industry and academia due to its low cost and reliability. However, the performance near or at zero current frequency is unsatisfying without extra excitation signals due to poor observability at zero current frequency. Here, for Q-MRAS method, authors propose new state equations. Based on these equations, authors analyze the observability and stability of IM drive with and without virtual voltage injection. Finally, based on virtual voltage injection, authors propose a new control scheme to solve the instability problem at zero current frequency.