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This paper proposes a wide-speed direct torque and flux control method associated with the inverter voltage and current constraints of interior permanent-magnet synchronous motors. The proposed approach has potential advantages controlling torque and flux linkage at the voltage and current limits, since no integrators are employed for torque control or flux weakening. The transition between the non-limited operation and maximum voltage modulation can be achieved automatically without modifying the control law. To confirm this, we provide a graphical and analytical analysis that naturally leads to a unique stator voltage vector selection on the hexagon. The proposed controller can maximize the available inverter voltage and generate a higher output torque than conventional current vector controllers at high speeds. The method developed in this paper also retains the beneficial features of classical direct torque control, such as its fast dynamics and direct manipulation of the stator flux linkage for flux weakening. [ABSTRACT FROM AUTHOR]

This paper presents a nonparametric approach to failure detection of broken rotor bars in inverter-fed induction motors (IMs). We lay the mathematical foundation for a diagnostic model of a rotor bar fault that captures the rotor bar high-frequency (HF) characteristics. The model shows that the HF equivalent motor resistance can be used as a direct indicator of broken rotor bars. It should be emphasized that the proposed detection methodology is applicable to any shape of rotor slot design by incorporating the idea of synchronous reference frame based injection and by taking the HF resistance as the fault detector. The proposed detection technique is also insensitive to other motor parameters and is effective under arbitrary load conditions. The full time-domain-based signature process provides efficient detection and enhances fault isolation. The identification scheme was implemented and tested on an inverter-fed 1.5-kW IM. [ABSTRACT FROM AUTHOR]

This paper presents a discrete time deadbeat-direct torque and flux controller (DB-DTFC) for interior permanent magnet synchronous machines (IPMSMs). A Gopinath-style discrete time flux linkage observer is developed which contains two different flux estimation methods based on current and voltage models for flux linkage. This observer produces correctly estimated flux linkages needed for accurate DB-DTFC implementation. In order to eliminate the sampling delay due to a characteristic of digital control computation, a complex vector model-based rotor reference frame current observer is also developed. Combining the discrete time current and flux linkage observers, the correct single time step (deadbeat) air-gap torque and stator flux linkage control at the (constant) switching frequency is achieved and experimentally evaluated. [ABSTRACT FROM AUTHOR]

Looks at an approach which uses the PWM inverter to identify the induction machine parameters. Importance of accurate induction machine parameters; Problem usually encountered with the inverter; Reference to the implementation of the proposed method.