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This paper investigates the optimal stator voltage angle in a rotor flux‐oriented system of an induction machine drive, aiming to maximise machine torque while operating in a deep field weakening region. Here, torque maximisation leads to maximum torque per voltage control, as only voltage constraints are relevant in this region due to high back‐electromotive force. Previous studies have predominantly focused on field‐weakening operation and torque maximisation, assuming a constant synchronous speed. However, for a given rotor speed, the variation in the dq voltage components impacts the slip speed, thereby influencing the synchronous speed. Therefore, this paper proposes enhanced analytical expressions to address this limitation. It is shown that after a linearisation around a suitable operating point, a closed‐form algebraic equation for calculating the speed and parameter‐dependent optimal voltage angle for torque maximisation can be obtained. The theoretical analysis is supported by numerical and experimental results. The presented linearised expression is proven to be an effective tool for the analytical calculation of the optimal voltage angle, making it suitable for real‐time control applications. It is shown that the proposed approach achieves higher drive torque and efficiency than the conventional voltage component distribution. [ABSTRACT FROM AUTHOR]

Accurate knowledge of induction machine parameters has a direct impact on the overall performance of field-oriented control strategies. In the case of rotor flux oriented control, parameter mismatch causes a discrepancy in the estimated rotor flux position and amplitude. Magnetising inductance is one of the parameters whose detuning has a direct impact on the setpoints of the control loops and estimation of hardly or non-measurable quantities. Conventional iron saturation, which can be obtained by a standard no-load test, is not the only type of saturation occurring in the machine. Depending on the rotor design, the magnetising inductance and the rotor leakage inductance may also strongly saturate as a function of load and, thus, rotor current. Based on the authors' previous work, a new, improved experimental method for identifying the load-dependent saturation of induction motor, which takes into account variation of the inverse rotor time constant, is proposed. Experimental results conducted on 12 kW motor show improved static and dynamic behaviour of the drive compared to the constant parameter model. [ABSTRACT FROM AUTHOR]