Induction motor drive parameters identification

Two online identifiers of the rotor parameters of the field-oriented (FO) induction motor drive are presented in this paper, The synthesis procedure of the identifiers is based on the model reference adaptive control (MRAC) system theory. An appropriate choice of the reference model allows building a Lyapunov function by means of which the updating law of the rotor time constant can be found. A higher order identifier is also synthesized using hyperstability approach. It allows the simultaneous identification of two rotor parameters. The parameters' convergence is assured thanks to the persistent exciting propriety of the input vector of the identifier, represented by the stator current. Experimental results conducted on an FO-controlled drive, using a digital signal processor (DSP)-based system (TMS320C31), having 40-MHz clock frequency, show the convergent trajectories of the parameters and of the state errors under various significant steady state and transient operating conditions and for different values of the adaption gains. The results show the satisfactory behavior of the proposed identification algorithms     

A self-commissioning algorithm for VSI-fed induction motors

In the paper, a self-commissioning algorithm is presented, which allows the determination of the parameters of an induction motor fed by a VSI, without any additional hardware, with respect to the one required by a vectorial control strategy. It is based upon the comparison between the measured and the predicted current response of the motor to an adequate feeding voltage waveform. The algorithm can be easily implemented as a start-up routine of the control software. In this way, a precise and quick evaluation of the motor parameters can be achieved. The validity and feasibility of the proposed algorithm are proved by experimental implementation.     

A novel approach to speed and parameters estimation in inductionmotor drives

With reference to speed controlled induction motor drives, an algorithm which allows the on-line estimation either of the speed and one motor parameter or, alternatively, of two motor parameters, is presented in the paper. The results obtained by simulation fully confirm the validity of the proposed algorithm. Finally, the problems arising from the implementation of the proposed algorithm on a DSP-based control hardware are analysed     

Position Measurement in Industrial Drives by Means of Low-Cost Resolver-to-Digital Converter

A fully integrated board for resolver-to-digital conversion is proposed in this paper. It is based on a combined analog/digital circuit, which allows one to track the shaft angle of a standard resolver in a digital form. Furthermore, the board also provides the feeding signal for the resolver-rotor circuit. All the tuning and configuration settings, which allow one to adapt different kind of resolvers to the proposed system, can be easily implemented directly on the board. The final assembly is a compact low-cost resolver-to-digital converter. The entire board design and implementation are described in this paper. In addition, several tests at different resolver speeds have been performed for validation.     

A space vector modulation algorithm for torque control of inverterfed induction motor drive

After a short review of the vectorial torque control (VTC) strategy, the design and setup of a dedicated modulation hardware unit is described in detail. Experimental comparisons with traditional induction motor control techniques fully confirm the validity of the proposed system     

EMC of power converters: the self-compatibility approach

Analysis of the internal electromagnetic compatibility of digitally controlled power converters is discussed. In particular, the optimum layout of the circuit configuration is designed on the basis of the actual electromagnetic interference between the power and the control section of a power converter. Besides, further improvements can be achieved by means of an auto- tuning additional board, which scans all the possible converter switching frequencies and analyses the distortion on the control signals corresponding to each frequency. Its main task is to select only the ones which produce low disturbances on the control signals as operating frequencies for the converter.     

Vectorial torque control: a novel approach to torque and fluxcontrol of induction motor drives

A general approach to torque and flux control of an induction motor fed by a voltage-source inverter is described in this paper. It is independent of whether rotor or stator flux is controlled. Based on this, an algorithm can be set up which allows the generation of the inverter switching patterns as a function of the reference values, both of the electromagnetic torque and of the controlled flux. Experimental comparisons with traditional direct torque control and field-oriented control techniques confirm the possibility of achieving very high dynamic performance with the proposed strategy     

Predictive compensation of dead-time effects in VSI feedinginduction motors

A predictive algorithm is presented in this paper, which allows the compensation of the dead-time effects in a voltage-source inverter feeding an induction motor, with space-vector pulsewidth modulation. It is based on the modification of the reference space vector of the feeding voltage according to a step-by-step analytical prediction of the stator phase currents. In this way, the effects of the dead time can be taken into account and compensated. The validity and feasibility of the proposed algorithm are confirmed by simulation and proved by experimental implementation