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As a new type of induction machine, brushless doubly-fed machine (BDFM) has excellent speed regulation performance and can run in the condition of variable-speed-constant-frequency power generation. It has good applicable potentials on energy-saving-speed-adjusting motors and wind power generation system, but its structure and operating principle are more complex. To study the effect of different...
The analysis and simulation of a doubly-fed induction machine used as a power flow control device is examined. This is a system that transfers power between one power system area and another using a doubly-fed induction machine as a rotary transformer containing rotor and stator windings. The ability to control the power flow by adjusting the rotor shaft angle is demonstrated. A test system was developed...
Indirect field oriented control for induction machine requires the knowledge of rotor time constant to estimate the rotor flux linkages. Here an online method for estimating the rotor time constant and stator resistance is presented. The problem is formulated as a nonlinear least-squares problem and a procedure is presented that guarantees the minimum is found in a finite number of steps. Experimental...
In industrial applications, when high dynamic performance is required, the induction machine is operated under field oriented control. This implies the knowledge of the machine main flux position at any time instant. In practical operation, the flux is calculated with mathematical models considering only the fundamental wave behavior of the machine. To maintain a stable operation of such a scheme...
Thermal models are often used in motor overload protection relays to predict rotor temperature. Under impaired cooling conditions, the parameters in the thermal models need to be tuned accordingly to reflect changes in the motor cooling capability. The tuning process requires accurate rotor temperature as a reference signal. This reference signal is estimated from the rotor resistance based on the...
In this paper, a stator power factor adjustable direct torque control of doubly-fed induction machine is proposed. The selection of rotor voltage vectors is performed based on the torque and the stator inactive current. The control system is built and the rotor voltage vector table is given. The feasibility of the proposed control strategy is examined through Simulink simulation experiments. Good...
Condition monitoring of electric machines is of increasing importance. The continuous assessment of the machine performance allows to schedule appropriately maintenance operations, thus increasing machine operating life and reducing repair cost. The input current spectrum is a wide spread procedure for non-invasive diagnosis of induction machines. Information on rotor variables are available only...
The transition of automotive industry from traditional combustion engines to hybrid vehicles and also research on renewable energies show a rapid need for more electrical machineries and consequently a huge demand for their condition monitoring and diagnostic systems. Prodigious improvement in signal processing techniques and availability of cost effective DSP hardware provide a road map for developing...
Available sensorless speed control strategy of doubly-fed induction machines uses the rotor flux to estimate the rotor position and speed. It fails around the synchronous speed due to the numerical errors of integration operation required by the rotor flux calculation. A novel control strategy is proposed in this paper. It uses the stator excitation current to estimate the rotor position and speed...
A speed estimation technique for induction machines based on carrier signal injection and the standard two-axis smooth air gap induction machine model is presented. The proposed speed estimation technique can work over a wide range of operating points, including DC excitation. The stability of the algorithm is analyzed using a two-time-scale approach. Based on the estimated rotor speed, a torque controller...
A new method for rotor broken bars fault diagnosis for induction machines based on the startup electromagnetic torque signal is presented. The fault characteristic torque frequency variation during the startup can be extracted using the wavelet ridge, which can be used to identify rotor broken bars fault. The wavelet coefficients modulus indicate the signal energy of the corresponding scale, so the...
This paper focuses on the experimental investigation of methods for the detection of stator faults in cage rotor induction machines fed by voltage source inverters (VSI). Three experimental investigations: unbalance in one stator phase, turn-to-turn fault in one phase and one stator phase open, have been performed to study the behavior of the electrical machine under these fault conditions. The work...
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