Vector Control of Asynchronous Motor of Drive Train Using Speed Controller H∞

This paper presents a neotype control strategy for maximum power point tracking (MPPT) of doubly-fed induction generator based wind turbine (DFIG-WT). The strategy adopts proportional-integral (PI) based regulators and feedback linearization control (FLC) based regulators in the power and current control loops of DFIG, respectively. The FLC based regulator can fully decouple and linearize the nonlinear system and provide optimal control performance in a wide range operating conditions. However, since the FLC strategy might require some unaccessible state variables of the mechanical system, the PI based regulators are able to simplify the control implementation in the power loop. Simulation studies are undertaken in a single-machine system operating under ramp-change and random wind profiles, respectively. Simulation results reveal that the proposed strategy performs better than the conventional vector control (VC) scheme under varying operation conditions.

Vector controlled multiphase induction machine: Harmonic injection using optimized constant gains

Vector control is an effective technique for controlling variable speed drives using brushless DC motors. Conventional vector controllers, however, suffer from electrical machine parameter variations because these controllers depend on the parameters. This paper presents the vector control of a brushless DC motor using a neural network. In the proposed method, a neural network is employed as an online estimator of the nonlinear dynamic equations of a brushless DC motor. The neural network based vector controller has the advantage of robustness against machine parameter variations as compared with the conventional vector controller. Computer simulation results verify the useful of the proposed method.

To improve the efficiency of a permanent magnet (PM) motor, it is usually required to extend the motor operation from linear to over or even six-step modulation regions based upon the space vector pulsewidth modulation technique. Traditionally, a PM motor is controlled by using the standard vector control technique. However, a recent study shows the decoupling inaccuracy of designing PM motor control using the conventional standard vector control approach. This issue has caused a challenge to control a PM motor, particularly when the motor operates from linear to overmodulation regions. In this article, a novel approximate dynamic programming (ADP) vector controller is developed to overcome the challenge. The ADP controller is developed using the full dynamic equation of a PM motor and implemented using an artificial neural network (ANN). A feedforward control strategy is integrated with the -based ADP controller to enhance the performance of the controller in both linear and overmodulation regions. The ANN-based ADP control is compared with the conventional standard vector control and a model predictive control. Simulation and hardware experiments demonstrate that the proposed controller can track reference changes better with high efficiency and reliability for PM motor operation in linear and overmodulation regions.

In general, rotating electrical machines can be modeled by an equivalent two phase machine. This means that an unbalanced 3-phase induction motor can be modeled by using an unbalanced two phase induction motor model. This paper shows this concept by modeling a faulty 3-phase induction motor in which one of its feeding phases is opened. The paper also presents a new fault-tolerant vector control (which is modified from the conventional vector control) that can be used to control a faulty three-phase induction motor. Simulation results show the good performance of the proposed method.

This paper presents an intelligent speed control system based on self tuning fuzzy PID controller for a brushless DC motor.PWM based motor current control is implemented with the help of three hall sensors placed around the motor shaft and a three phase inverter model is implemented for motor commutation .Dynamic performance of electromagnetic torque developed are analysed for this model. Traditional speed control system of BLDCM introduces conventional PI regulator in outer speed loop which debases the performance of whole system. To overcome this problem, replacement of PI controller by an intelligent controller based on fuzzy set theory is proposed. The performance of the intelligent controller has been investigated through Matlab Simulink package for different operating conditions such as sudden changes in load torque. The simulation results demonstrate that the performance of the proposed controller is better than that of conventional PI controller.

A concept of decoupling control in the strategy of the speed regulation of the squirrel cage induction motor with controlled voltage source is represented. The decoupling control intends to cancel out the cross terms between the secondary flux and the secondary current. Three necessary and sufficient conditions for the decoupling control are offered that correspond to taking into account the effect of the primary impedance in the control strategy. Phase lead compensation with the slip frequency control allows the realization of the decoupling control, which is found to be an extension of both the conventional vector control and the constant volts/hertz control. Numerical and experimental results are also shown.

This paper presents the methodology of single phase induction motor (SPIM) speed control by multi frequency and new binary rate multipliers (BRM) technique that gives rise to suitable energy supply to motor at any instant. Knowing the voltage and current, power is calculated by vector space method. The result is feedback to two proportional-integral (PI) controllers for processing by means of frequency 40 to 80 Hz and BRM which gives the patterns up to 256 forms. It shows fast time response of returning to normal state, both loading and no load, not exceed 1.0 seconds. The superiority of this technique is that both apparent and reactive power decrease while running at no load and full load power factor increase up to 0.444 and 0.633 respectively. Thus, higher efficiency is achieved.

Authors have proposed a three-degree-of-freedom resonant actuator that was able to be driven in three axes. However, a mutual interference of thrust was not considered in the conventional vector control. In this paper, we propose a novel vector control theory for three-degree-of-freedom resonant actuator. A mathematical model of d-q conversion is theoretically introduced and the effectiveness of the proposed method is verified by confirming the thrust linearity with respect to the mover position.

The speed control of a switch reluctance motor (SRM) using feedback control method with the help of a proportional integral (PI) controller is presented in this paper. The paper proposes the design of a PI controller for a 6/4 SRM under different load conditions. The control mechanism is designed such that the motor runs at half of the rated speed for first few cycles and then attains the rated speed for the remaining cycles. The values of the controller gains Kp, Ki are tuned in such a way that the rated speed is maintained under different operating conditions. MATLAB Simulink is used to illustrate the simulation results for the motor at zero, half and full load conditions. The simulation results are compared and analyzed.

A large-capacity low-speed flywheel energy storage system based on a doubly-fed induction machine (DFIM) basically consists of a wound-rotor induction machine, and a back-to back converter for rotor excitation. It has been promoted as a challenging storage system for power system applications such as grid frequency support/control, power conditioning, and voltage sag mitigation. This paper presents a power control strategy to charge/discharge a flywheel doubly-fed induction machine storage system (FW-DFIM) to obtain a constant power delivered to the grid. The proposed controller is based on conventional vector control, where an artificial neural network (ANN) is used to develop the required rotor current component based on the required grid power level and the flywheel instantaneous speed. This technique is proposed for power levelling and frequency support to improve the quality of the electric power delivered by wind generators, where a constant power level can be delivered to the grid for a predetermined time depending on the required power level and the storage system inertia. The controller is designed to avoid overloading stator as well as rotor circuits while the flywheel charges/discharges. The validity of the developed concept in this paper, along with the effectiveness and viability of the control strategy, is confirmed by computer simulation using Matlab/Simulink for a medium voltage 10MJ/1000hp FW-DFIM example. (6 pages)

This paper investigates the use of a static synchronous compensator (STATCOM) to mitigate the voltage fluctuations and improve fault ride-through capability of wind farm with fixed speed induction generators. In order to assure STATCOM of running safely and reliably in both normal and faulty conditions, a novel control strategy which combines negative-sequence voltage feed-forward control with conventional vector control is proposed to make the negative sequence current of STATCOM zero and effectively suppress STATCOM overcurrent. The positive-sequence and negative-sequence components of the voltage at point of common coupling (PCC) are obtained quickly and accurately by the specially designed double synchronous reference frame phase locked loop (DSRF PLL). The simulation results show that the STATCOM not only significantly improves the power quality, but also enhances fault ride-through capability of wind farm. It is also concluded from the simulation results that the proposed control strategy can effectively suppress STATCOM overcurrent and guarantee that STATCOM can operate safely even in abnormal conditions.

This paper presents nonlinear backstepping control for Wind Power Generation System (WPGS) based Permanent Magnet Synchronous Generator (PMSG) and connected to utility grid. The block diagram of the WPGS with PMSG and the grid side back-to-back converter is established with the dq frame of axes. This control scheme emphasises the regulation of the dc-link voltage and the control of the power factor at changing wind speed. Besides, in the proposed control strategy of WPGS, Maximum Power Point Tracking (MPPT) technique and pitch control are provided. The stability of the regulators is assured by employing Lyapunov analysis. The proposed control strategy for the system has been validated by MATLAB simulations under varying wind velocity and the grid fault condition. In addition, a comparison of simulation results based on the proposed Backstepping strategy and conventional Vector Control is provided.

This paper presents a hybrid wavelet-fuzzy based multiresolution (MR) controller for robust speed control of induction motor. The discrete wavelet transform (DWT) is used to decompose the error between the actual speed and command speed of the induction motor drive in to different frequency components. A self-tuning fuzzy logic is used for online tuning of the controller parameters. The proposed controller has the ability of meeting the speed tracking requirements in the closed loop system. The complete indirect field oriented control scheme incorporating the proposed wavelet-fuzzy based MR controller is investigated theoretically and simulated under various dynamic operating conditions. Simulation results are compared with that of conventional PI controller and fuzzy based PI controller. The speed control scheme incorporating the proposed controller is implemented in real time using the digital processor (DSP) control board. Simulation and experimental results validates the effectiveness of the proposed controller over conventional controllers and proves to be more suitable for high performance applications.

A vector controlled medium voltage AC motor drive is proposed in this paper which is based on a current source topology consisting of a PWM GTO current source inverter (CSI) as the output connected to the motor and a two-module PWM GTO current source rectifier (CSR) as the front end. The output inverter is operated with selective harmonic elimination (SHE) patterns with variable fundamental frequency and a maximum switching frequency of 300 Hz. The conventional direct vector control strategy for induction motors is adapted to incorporate the effect of the output capacitors of the CSI. The front end two-module PWM GTO CSR is operated with an SHE pattern eliminating the 11th and 13th harmonics and is connected to the AC mains through a three winding transformer which also eliminates the 5th, 7th, 17th, 19th harmonics. The regulation of the DC link current is achieved by phase shifting the SHE pattern of the rectifier modules. The paper includes the study and analysis of the front end topology, the input transformer, input harmonic characteristics, input power factor for various industrial loads, the inverter control strategy, simulation results and experiments on a 50 kVA system.