Evaluation of dynamic parameters and performance of deep-bar induction machines

Deep rotor bar induction machines have good starting characteristics as compared with cylindrical bar squirrel-cage configurations. High starting torque is achieved by the speed-dependent secondary resistance. The variation of secondary resistance and leakage inductance determines the machine starting and acceleration performance. Conventional measurement methods can only provide nominal parameters under blocked rotor and no-load test conditions. This makes details of the dynamic parameters and an evaluation of the acceleration performance from standstill ill-defined. To determine the starting characteristics of deep bar induction machines, a knowledge of the dynamically varying parameters is needed. This report demonstrates the application of a new algorithm to identify the variable parameters of deep rotor bar induction machines, namely secondary resistance and secondary leakage inductance, based on the easily measurable terminal conditions of the machine, namely voltage, current and rotational speed. This algorithm is simply an algebraic operation, which is always stable and easily realizable and no convergence problems arise. Practical application of this method to an 18 pole, 60 Hz, 871 hp deep bar induction motor demonstrates the performance of the new parameter identification method