Piezoelectric traveling wave rotary ultrasonic motors are motors that generate torque by using the friction force between a piezoelectric composite ring (or disk-shaped stator) and a metallic ring (or disk-shaped rotor) when a traveling wave is excited in the stator. The motor speed is proportional to the amplitude of the traveling wave and, in order to obtain large amplitudes, the stator is ex...

In this chapter, a new method for stator resistance compensation in direct torque control (DTC) drives, based on neural networks, is presented. The estimation of electromagnetic torque and stator flux linkages using the measured stator voltages and currents is crucial to the success of DTC drives. The estimation is dependent only on one machine parame‐ ter, which is the stator resistance. Chang...

This paper presets steady state behavior of Direct Torque Control (DTC) of Induction motor (IM) drive. As in direct torque and flux control scheme electromagnetic torque and stator flux magnitude of induction motor drive is limited in closed loop without shaft sensors voltage modulator. This values are calculated with the help of dc link voltage of inverter and stator current. As during estimat...

In this paper some sensorless strategies for induction motor drives are reviewed and analyzed. A method for accurately obtaining the PWM stator voltage is used to minimize the problem of estimating stator flux from the stator voltage equation in low speeds. A Gopinath style stator flux observer is presented and its capability to compensate for stator voltage errors is discussed.

Stator faults typically have a significant share amongst the common type of faults in industrial three-phase induction (asynchronous) motors. This paper presents a motor current signature analysis (MCSA)-based diagnostics of the stator winding short circuit fault. This type of fault happens due to the destruction of the turn insulation, and can be very detrimental causing motor shutdown. Instea...

This paper proposes an algorithm for direct flux and torque controlled three phase induction motor drive systems. This method is based on control of slip speed and decoupled between amplitude and angle of reference stator flux for determining required stator voltage vector. Within the given sampling time, flux as well as torque errors are controlled by stator voltage vector which is evaluated f...

Stator resistance identification algorithm for AC induction motor is presented in this paper. It does not require additional external excitation. The algorithm is intended to capture slow variations of stator resistance which are given by the changes in stator windings temperature. Steady state operation with harmonic voltages and currents are located during the operation of the motor and the s...

This paper presents a simple control method for controlling permanent magnet synchronous motors (PMSM) in a wide speed range without a shaft sensor. The method estimates the stator flux by integration of the measured BEMF signal. To compensate for the offset in the BEMF the offset is estimated. The control method is made robust at zero and low speed by changing the direct vector current compone...

Abstract: The generator stator current gets distorted with unacceptable levels of total harmonic distortion (THD) because impedance-source wind power generation systems use three-phase diode rectifiers. The stator current harmonics will cause increasing losses and torque ripple, which reduce the efficiency and stability of the system. This paper proposes a novel half quasi-Z-source inverter (H-...

In this paper, a novel stator current based Model Reference Adaptive System (MRAS) estimator for speed estimation in the speed-sensorless vector controlled induction motor drives is presented. In the proposed MRAS estimator, measured stator current of the induction motor is considered as a reference model. The estimated stator current is produced in an adjustable model to compare with the measu...