Field Oriented Vector Control Research Articles

Automatic Measurement of Stator Resistance for Permanent Magnet Synchronous Motors Based on Simple Linear Regression Model

In the field-oriented vector control system of permanent magnet synchronous motor (PMSM), the performance is directly dependent on the accuracy of motor parameters. Because of nonlinear factors of the inverter, the difficulty in accurate compensation of voltage error and low accuracy of measurement are problems which exist in stator resistance identification approach based on traditional DC voltmeter-ammeter method. In this paper, the ordinary least squares method based on simple linear regression model is used to finish the automatic measurement of stator resistance. It is verified that the method has higher measurement accuracy according to the experimental result. Furthermore, nonlinear factors of the inverter are not needed to be taken into account using the method, which has comparatively strong practicality in engineering.

Permanent Magnet Synchronous Motor Drive System Based on Fuzzy Control

A permanent magnet synchronous motor fuzzy control drive system based on field programmable gate array is proposed in this paper. This system has the high-precision control characteristic, which is hard for the traditional permanent magnet synchronous motor drive system to achieve. In this system a magnetic field oriented vector control with a zero excitation current is used, and three feedback loops consisting of current loop, velocity loop and position loop are used to build three fuzzy proportional integral controllers with fuzzy control method. The reliability and the dynamic of system performance can be improved by this method. The experimental results show that this system has advantages of high-precision control characteristic and enhancing the system robustness.

Modeling, Control and Experimental Validation of a Flywheel-Based Energy Storage Device

This work deals with the modeling, control and experimental validation of a flywheel-based energy storage device. The system is based on a low-speed rotating disk mechanically coupled to a Permanent Magnet Synchronous Machine (PMSM). The electrical power is exchanged with the external grid by means of a set of back-to-back power converters. These power electronics control the speed of the machine, and thus the active power absorbed or injected by the device, and also regulate the reactive power at the point of common coupling with the external grid. Vector control techniques are used for designing the converter controllers: a field oriented vector control algorithm is implemented for governing the servomotor while an instantaneous power theory-based algorithm is used to manage the active and reactive currents flowing from the grid side converter. The control implementation in the experimental setup has been carried out by means of programming Digital Signal Processors (DSP’s). The modeling and control system design has been validated after executing several experiments. Other characteristics such as the torque losses of the system as well as the system performance concerning energy rating, power rating and energy efficiency characteristics are determined experimentally.

PMSM Control System Based on a Improved Sliding Mode Observer

In order to improve the performance of sensorless PMSM control system, an improved sliding mode observer (SMO) is proposed in this paper. To decrease the vibration of SMO, a variable switching gain which changes according to the winding currentn is adopted. To improve the estimated value of rotor position, a extra low pass filter (LPF) is employed and the linear interpolation method is used to calculate compensation value of the phase delay caused by LPF. To verify the performance of proposed SMO, a sensorless field oriented vector control system of PMSM is designed. At last, the performance of the improved SMO and the sensorless PMSM vector control system are verified by experimental results.

The Speed and Position Control Method for Constant Magnetism Synchronous Motors Running at Low Speed

In the rotor field oriented vector control system, the use of permanent magnet synchronous motor voltage equations and flux equations derived PMSM position and speed estimation method has its unique advantages, The advantage of this approach is to calculate a simple, fast dynamic response, and easy to implement. However, when permanent magnet synchronous motor running at low speed, back EMF would be very small, which can not guarantee the accuracy of estimates. In addition, the position and speed estimation parameters of permanent magnet synchronous motor is largely in dependence on the running status of permanent magnet synchronous motor ,and vulnerable to temperature and magnetic saturation phenomena.All of these elements will lead to error increase. In order to solve the problem of inaccuracy in parameters estimation of motors at low speed, PI controller is introduced to obtain the rotor speed information, and then make up for deficiencies in the estimation algorithm. At the same time, this method can be applied to achieve smooth switching of high speed switching of the motor.

DSP Based Simulator for Speed Control of the Synchronous Reluctance Motor Using Hysteresis Current Controller

This paper presents the field oriented vector control scheme for synchronous reluctance motor (SRM) drives, where current controller followed by hysteresis comparator is used. The test motor has a star-connected wound stator and a segmental rotor of the multiple barrier type with an external incremental encoder to sense rotor position. The magnetic characteristics of this motor are described using 2D finite element method, which is used firstly for rotor design of SRM. The field oriented vector control, that regulates the speed of the SRM, is provided by a quadrature axis current command developed by the speed controller. The simulation includes all realistic components of the system. This enables the calculation of currents and voltages in different parts of the voltage source inverter (VSI) and motor under transient and steady state conditions. Implementation has been done in MATLAB/Simulink. A study of hysteresis control scheme associated with current controllers has been made. Experimental results of the SRM control using TMS320F24X DSP board are presented. The speed of the SRM is successfully controlled in the constant torque region. Experimental results of closed loop speed control of the SRM are given to verify the proposed scheme.

Vector Control for Connectionless Two-Motor Synchronous System

According to two three-phase asynchronous motors system running by connectionless-mode, and considering the system to be required to run in strict synchronous way under different load, the method of field-oriented vector control is used. Thus, the control loops of rotor flux, torque and rotor speed are constructed to make two-motor system run synchronously by torque distribution. The simulation results illustrate its effectiveness and good dynamic and static performance.

Direct-Flux Vector Control of IPM Motor Drives in the Maximum Torque Per Voltage Speed Range

The high-speed operation region of interior permanent magnet (PM) (IPM) motor drives is investigated, with particular attention to the maximum-torque-per-voltage operation. A technique is proposed for the control of the drive in such region, based on direct-flux field-oriented vector control. The proposed control is easy to implement, does not require the accurate knowledge of the motor model, and showed to be robust toward the effects of iron losses, position estimation errors, and dc-link variations. Moreover, it is suitable for operation in the inverter overmodulation range. Experimental results are provided for a 600-W IPM drive for home appliances.

Predictive Functional Control for the Induction Motors Based on FOC

Abstract The control system of induction motor used in EV is studied in this paper. The new PFC controller based on rotor flux field-oriented vector control is designed in order to overcome the effects of uncertainties of unpredictable parameter variations and external load disturbances. The SVPWM control strategy is used to realize high-efficient control scheme. The simulation and experiment results indicate that the PFC algorithm can achieve better dynamic and static properties and stronger robustness than the conventional PI controller, and can track the given trajectory primly. It is well suited for electric-driven system.

Simulation software for CRH2 and CRH3 traction driver systems based on SIMULINK and VC

Simulation models of traction driver systems were established using SIMULINK, according to the actual structure and parameters of China Railway High-Speed 2 (CRH2) and China Railway High-Speed 3 (CRH3) trains. In these models, the traction motor adopts transient current control and an indirect rotor magnetic field orientation vector control strategy, and the traction converter uses sinusoidal pulse width modulation (SPWM) and space vector pulse width modulation (SVPWM) methods. After these models are transformed in VC++ program, and a friendly interface and data processing system are constructed, simulation software is obtained for CRH2 and CRH3 traction driver systems. On this basis, the operational performance of a traction converter was simulated and analyzed at different train speeds and in different conditions. The simulation results can provide a reference for the actual design and production of a traction converter.

Simulation Study of Variable-Frequency Speed-Regulation Vector Control System of Asynchronous Motor

Vector control technology is regarded as a kind of controlling manner of AC asynchronous motor and it has already become the first method of the high-performance variable-frequency speed regulating system. According to the basic principles of induction motor vector control, this paper constructs simulation model of rotor magnetic field oriented vector control system based on the MATLAB software. The paper analyzes the operation of motor on the basis of mutation of a given speed and sudden load. The simulation result including the oscillogram speed, torque,three phase current and two phase current were presented and analyzed. Results show that it has good dynamic performance, and it realizes the decoupling control system.

Research on Adaptive Rotor Flux Observer with the Speed Feedback and Rotor Resistance Disturbing

Rotor flux observation is a key step in implementation of a field-oriented vector control system. Aiming at eliminating the influence of the actual speed fluctuation and rotor resistance variety, an adaptive rotor flux observer was proposed to accurately estimate the flux of induction motors in modern high performance drivers, based on the conception of close-loop flux estimation and the extended state observer theory. The performance of the proposed scheme is verified through simulation and experiment.

Enhanced Hysteresis-Based Current Regulators in Vector Control of DFIG Wind Turbines

This paper proposes enhanced hysteresis-based current regulators in the field-oriented vector control of doubly fed induction generator (DFIG) wind turbines. The proposed control scheme is synchronized with the virtual grid-flux space vector, readily extractable by a quadrature phase-locked loop (QPLL) system. Identical equidistant-band vector-based hysteresis current regulators (VBHCRs) are then used to control the output currents of the rotor-side and grid-side converters. The proposed hysteresis-based technique has excellent steady-state performance and reveals several advantages in comparison with the commonly used proportional-integral (PI) current regulator, including very fast transient response, simple control structure, and intrinsic robustness to the machine parameters variations. Moreover, the fixed hysteresis bands in VBHCRs are replaced with equidistant bands to limit the instantaneous variations of the switching frequency and reduce the maximum switching frequencies experienced in the converters. Extensive simulation studies are carried out for a 1.5 MW DFIG-based wind turbine to examine the operation of the proposed vector control scheme under changing wind speed and compare its transient and steady-state performances with the conventional PI current regulators.

Output Voltage Correction for a Voltage Source Type Inverter of an Induction Motor Drive

A proposed voltage error correction method that uses a disturbance observer for various types of induction motor control was evaluated. The features of the proposed control method are: 1) control parameters are easily determined according to the motor model and the parameter sensitivity is robust, and 2) the proposed method can be applied for field-oriented vector control, speed sensor-less vector control, and <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">V</i> / <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">f</i> control of the induction motor by modification of a back electromotive force compensation term in the observer. The disturbance observer is designed to have fast response that is ten times faster than the current controller for vector control. The voltage error is efficiently corrected using the proposed method, and the current distortion can be reduced by approximately 1/3. The proposed method is validated on the basis of experimental results.

Modelling and characteristics analysis of the pitch system of large scale wind turbines

The individual pitch drive system of large-scale wind turbines was analysed in this article. In this pitch system, the induction motor, three-stage planetary gearbox, and motor vector control were adopted. In order to investigate the system dynamic behaviour, its non-linear dynamical model was established, mainly including three parts: induction motor model in d— q frame, dynamic model of three-stage planetary gears, and transmission shaft model. The dynamic responses of gearbox—blade subsystem and motor—gearbox—blade system were analysed in detail, respectively. Then, the pitch system control model was established in which rotor flux field-oriented vector control and double close-loop servo control with speed and position feedback were employed. In simulation, the algorithm TR-BDF2 was adopted to solve the dynamic equations. The research results show that the deviation between the pitch angle and its command value is very small in steady state, pitch speed and acceleration fluctuations appear when impact effect is produced due to gear backlash, and the different blade may have different variable pitch speed and acceleration in some pitch region. The research results give a reasonable explanation for running mechanism of the individual pitch system and are helpful for optimization design and control for the individual blade pitch control system used in large-scale wind turbines.

Design and Implementation of a Novel Vector-controlled Drive by Direct Injection of Random Signal

The distribution of harmonics of an inverter output voltage in a PWM inverter can be improved by using a Random Pulse Width Modulation (RPWM) scheme. RPWM dose not affect the fundamental frequency component of voltage, however it can significantly reduce the acoustic noise and mechanical vibrations of an inverter-fed ac motor drive. Up to now, RPWM has been studied in many researches and various RPWM techniques have been introduced, but none of them have actually shown the effects of the behavior of the random signal on the frequency spectrum of the inverter output voltage and performance of the motor drive. In this paper, three different methods of random signals are employed. These different methods and the Probability Density Function (PDF) of the random signal generator will be studied and the performance of the drive is examined. Also a new method in utilizing random signal is proposed. In this method, the random signal is injected to reference value of the quadrature-axis current. It should be noted that the RPWM technique can not be utilized in hysterisis drives. Here, the random signal with different PDF is injected directly to quadrature axis current. The injection of random signal will directly affect the output responses. In this research, comparison between RSPWM technique and direct injection of random signal has been carried out. Different criteria such as total harmonic distortion (THD), torque ripple and frequency spectrum, efficiency and mechanical vibration have been analyzed. The indirect field oriented vector control drive is simulated by using Matlab-Simulink first, and the effects of various methods of employing random signal are compared and the best alternative is introduced. For the validation of the simulation results an experimental set-up is built. The experimental results confirm the simulation outputs. The simulation and experimental result show superiority of Direct Injection of Random Signal (DIRS) method in comparison with randomized Sinusoidal pulse width modulation (RSPWM) technique. Also it is realized that the DIRS method is very simple for implementation and does not need any extra hardware.

Vector Control of Multimotor Drive

Three-phase induction machines are today a standard for industrial electrical drives. Cost, reliability, robustness and maintenance free operation are among the reasons these machines are replacing dc drive systems. The development of power electronics and signal processing systems has eliminated one of the greatest disadvantages of such ac systems, which is the issue of control. With modern techniques of field oriented vector control, the task of variable speed control of induction machines is no longer a disadvantage. The need to increase system performance, particularly when facing limits on the power ratings of power supplies and semiconductors, motivates the use of phase number other than three, In this paper a novel scheme of connecting two, three phase induction motors in parallel fed by two inverters; viz. VSI and CSI and their vector control is presented. Keywords—Field oriented control, multiphase induction motor, power electronics converter.

Dynamic control of torque in overmodulation and in the field weakening region

At high angular velocity, the induction motor is operated in the field weakening range due to the voltage limit of the inverter. Field oriented vector control (FOC) is unsuitable for this operation duetocoupling, non-linearities,andsaturationof linear current controllers. A proposed direct torque control space vector modulation (DTC–SVM) scheme using SVM does not use coordinate transforms or current controllers to achieve DTC. Control of the stator flux vector allows for dynamic change in the torque in all regions,including field weakening with the six-step operation. This paper describes the torque control dynamic in the field weakening range, using a step change in stator flux vector magnitude and it’s angular velocity. The method is demonstrated experimentally.

A Novel Observer-Based Flux Estimation for Speed Sensorless DFO Control of Induction Machine

This article proposes a novel closed-loop rotor flux observer to estimate the rotor flux and velocity of induction motors. With the proposed algorithm, the accuracy of the estimated flux is guaranteed when the estimated stator current converges to its actual one. With the help of the estimated rotor flux magnitude and angle information, the direct rotor field orientation vector control can be implemented, and the rotor speed can be derived. Compared with the traditional Luenberger observer, the salient advantage of the proposed observer-based flux estimation is that the flux estimation is independent of either the estimated speed error or rotor time constant deviation. The validity of the proposed method is verified by intensive digital simulation results.

Field-Oriented Vector Control of Synchronous Motors With Additional Field Winding

This paper presents a new method to control a synchronous motor in such a way to resemble the characteristics of a DC motor. The method suggests including a second field winding to the rotor of a voltage-source-inverter-fed synchronous motor. The angular frequency of the inverter is made equal to the angular rotor speed, (of a self-controlled synchronous motor drive). The added field winding is in space quadrature to the main field winding and is properly excited in such a way as to diminish the direct axis component of the stator current at every load conditions. The motor is controlled to operate with zero power angle from the inverter side and zero direct axis current from the rotor excitation side. Therefore, it operates with minimum stator current and with unity power factor. The addition of the second field winding will not complicate the design because it is just a control winding. This winding may be made with smaller wire cross-section and a larger number of turns. The control on this winding is not complicated and it can be easily created. The synchronous motor along with the added field and the required control loops are simulated and tested extensively. The test results show excellent motor performance in motoring and regenerating modes of operation.