Study on Direct Torque Control Methods of a Doubly Fed Induction Machine Working as a Stand-Alone DC Voltage Generator

Abstract

The paper presents a comparison of different Direct Torque Control methods of a Stand-Alone Doubly Fed Induction DC-Voltage Generator, with classic field oriented control used as a benchmark. The system consists of a doubly fed induction generator the stator circuit of which is connected to the DC-bus with a diode rectifier, and the rotor circuit converter is connected to the same DC bus. The main problem of this power generation system are large torque oscillations caused by a nonlinear diode rectifier connected to the stator. Three direct torque control algorithms are described as a means of reduction of this drawback with simultaneous control of DC bus voltage and stator voltage frequency. The methods differ by the second variable used for control in parallel to the torque control path. The selected second variable is the d component of the rotor current vector, the d component of the stator flux or the stator flux module.

Tuning of Pi Speed Controller in Direct Torque Control Ofdual Star Induction Motor Based on Genetic Algorithms and Neuro-Fuzzy Schemes

“…The fundamental idea behind the DTC concept is to achieve decoupled control of both flux and torque by properly selecting the stator voltage analogous to the torque and flux error, and this choice is based on the utilization of hysteresis controllers, the outputs of the hysteresis regulators when combined with information about the flux position, determine the optimal voltage vectors. These vectors enable the inverter VSI to reach seven distinct phase-plane positions, which correspond to the inverter output voltage vector's eight sequences [8,14,27]. The stator and rotor (α,β) fluxes' magnitudes can be evaluated as follows.…”

A Comparative Study of Cutting-Edge Bi-Directional Power Converters and Intelligent Control Methodologies for Advanced Electric Mobility

“…Comparison of DTC techniques for DFI DC Generators, focusing on decreasing torque oscillations caused by nonlinear diode rectifiers and regulating the DC bus voltage and stator frequency [98]. The 5D-DTC method for six-phase induction machines uses hysteresis regulators and clustering to suppress the current and address harmonics [99]. Lookup Table-based Model Predictive Direct Torque Control (LUT-MPDTC) enhances the performance of a synchronous generator with a Vienna rectifier by reducing torque and flux ripples and minimizing computational problems compared with traditional DTC.…”

A new method of virtual direct torque control of doubly fed induction generator for grid connection

“…As a result, this method is able to control and maintain the correct and optimal angular position between the effective spatial vectors in the behavior of the induction machine in the stable and transient state. The virtual torque control is derived from the direct torque control, with the difference that instead of the electromagnetic torque, we use a virtual torque which is calculated from the byproduct of the rotor's flux and the network's virtual flux [13].…”