Sensorless Vector Control Method Research Articles

New sensorless vector control methods based on a new minimum-order flux state observer in the ?D-module? for permanent magnet synchronous motors

This paper proposes new sensorless vector control methods that can be applied to both salient-pole and non-salient-pole permanent magnet synchronous motors (PMSM). The proposed method estimates the phase of rotor flux by the “D-module observer,” which is newly developed for sensorless vector controls of PMSM. The “D-module observer” has the following attractive features. (1) It is a new state observer requiring no additional approximation to the motor mathematical model. (2) It is a minimum-order state observer. (3) Observer gain guaranteeing proper estimation in a wide operating range except for singular zero-speed can be a simple constant, and can be easily designed. (4) It utilizes motor parameters in the simplest manner. (5) Its structure is very simple and is realized at the minimum computing cost. (6) It can be applied to both salient-pole and non-salient-pole PMSM. (7) It can be realized in both rotor and stator reference frames. Detailed designs and analyses for the “D-module observer” and “D-module observer”-based sensorless vector control systems in both rotor and stator reference frames are given. Their validity and usefulness are examined and confirmed through extensive experiments. © 2005 Wiley Periodicals, Inc. Electr Eng Jpn, 151(2): 46–62, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20046

A New Sensorless Vector Control Method for PMSM Based on a New 4th-Order State-Observer in Stationary Reference Frame with the "Integral-Feedback Type Speed Estimator"

This paper proposes a new sensorless vector control method for permanent-magnet synchronous motors (PMSM), which uses a new full-order (4th order) state-observer in stationary reference frame combined with the “integral-feedback type speed estimation method". The proposed method can be applied to both of salient and nonsalient PMSM.

Sensorless Vector Control of Induction Machines for Variable-Speed Wind Energy Applications

A sensorless vector-control strategy for an induction generator in a grid-connected wind energy conversion system is presented. The sensorless control system is based on a model reference adaptive system (MRAS) observer to estimate the rotational speed. In order to tune the MRAS observer and compensate for the parameter variation and uncertainties, a separate estimation of the speed is obtained from the rotor slot harmonics using an algorithm for spectral analysis. This algorithm can track fast dynamic changes in the rotational speed, with high accuracy. Two back-to-back pulse-width-modulated (PWM) inverters are used to interface the induction generator with the grid. The front-end converter is also vector controlled. The dc link voltage is regulated using a PI fuzzy controller. The proposed sensorless control strategy has been experimentally verified on a 2.5-kW experimental set up with an induction generator driven by a wind turbine emulator. The emulation of the wind turbine is performed using a novel strategy that allows the emulation of high-order wind turbine models, preserving all of the dynamic characteristics. The experimental results show the high level of performance obtained with the proposed sensorless vector-control method.

New Sensorless Vector Control Methods Based on a New Minimum-Order Flux State-Observer in the "D-Module" for Permanent Magnet Synchronous Motors

This paper proposes new sensorless vector control methods that can be applied to both of salient-pole and non-salient-pole permanent magnet synchronous motors (PMSM). The proposed method estimates the phase of rotor flux by the “D-module observer”, which is newly developed for sensorless vector controls of PMSM. The “D-module observer” has the following attractive features. 1) It is a new state observer requiring no additional approximation to the motor mathematical model. 2) It is a minimum order state observer. 3) Observer gain guaranteeing proper estimation in four quadrants wide operating range except singular zero-speed can be a simple constant, and can be easily designed. 4) It utilizes motor parameters in the simplest manner. 5) Its structure is very simple and realized at the minimum computing cost. 6) It can be applied to both of salient-pole and non-salient-pole PMSM. 7) It can be realized in both rotor and stator reference frames. Detailed designs and analyses for the “D-module observer” and “D-module observer” based sensorless vector control systems in both rotor and stator reference frames are given. Their validity and usefulness are examined and confirmed through extensive experiments.

Neural network-based stator voltage compensator for low-frequency operation of a vector-controlled induction motor drive

The stator field-oriented sensorless vector control method is receiving wide attention from the standpoints of being sensorless and less dependent on the motor parameters. However, this method has a problem at low speeds because actual stator voltage does not coincide with the corresponding reference voltage owing to the quantization error in the controller, the discrete-time process, the forward voltage drop of switching devices, and the dead time of the inverter. In this study, an artificial neural network-based voltage compensator is proposed to reduce the voltage error between the reference and the actual voltages. The proposed method was performed on an experimental system and the results were found to be excellent.

Speed Sensorless Vector Control Method of Induction Motor Including A Low Speed Region

In the recent years, many speed sensorless control method with adaptive observer of induction motor have been developed. The feedback gain of observer is designed from the responsive viewpoint of the error convergence. When we drive induction motor in the low speed region with each method, the control characteristic is deteriorated. In this paper, we give the design of the speed sensorless adaptive flux observer in the low speed region and propose speed sensorless vector control system with it from the stable viewpoint of the error convergence. And we show experimental results of this method.

Speed Sensorless Vector Control of Induction Motor as Influenced by Core-Loss

This paper is aimed at developing a method of speed sensorless vector-control of induction motor drive systems, taking into consideration stator and rotor core losses. To validate the correctness of the method, the calculated motor speed, rotor flux, and stator current are compared with those measured in the literature. Moreover, the present calculated values in the presence of core losses are also compared with those calculated before in absence of the core losses. It is concluded that consideration of core losses in the dynamic model of the machine improves the theoretical predictions and reduces the discrepancies between the calculated and measured values.

A New Method of Sensorless Vector Control for Induction Motors Using Instantaneous Reactive Power

This paper proposes a new method of sensorless vector control for induction motors, in which the motor speed is estimated by both instantaneous reactive power and variation of magnetizing current. The proposed system is constructed in a synchronously rotating reference frame and is very simple. Another advantage is that the proposed system can work in regenerating mode without any special technique. A linear model is deduced to analyze system stability. According to the trajectories of poles and zeroes, the system gain is selected to be suited for operating in a wide speed range and in motoring or regenerating mode. The feasibility of the proposed system is verified by digital simulation.

An alternative sensorless field orientation method

This paper proposes a sensorless vector control method to achieve field orientation in induction motor drive systems. The field orientation strategy is based on the concept of varying the stator frequency with respect to a slip difference. A general equation for calculating the slip in any reference frame is developed. A reduced order discrete rotor flux observer with small sensitivity to rotor resistance and slip variations is used. The whole control system operates in a synchronously rotating frame. Only stator voltages and currents are sensed. A different approach in implementing this method through a frequency PID is also presented. Simulation results are used to verify the validity of the proposed alternative sensorless field orientation technique.

Observer-based speed estimation method for sensorless vector control of induction motors

The method is based on an adaptive flux observer in the rotor-speed reference frame, in which a second-order Kalman filter is employed to modify the estimated rotor flux to improve the performance of speed estimation. The Kalman filter modifies the estimated rotor flux based on the measured stator currents. The estimated speed is used in the speed feedback for vector control and in the co-ordinate transformation for current controller. The proposed method has the advantage of saving much computation time in comparison with the reduced-order extended Kalman filter. Compared with the conventional adaptive observer, the proposed method has the advantage of better accuracy to follow the speed command under heavy loads. Experimental results show the effectiveness of the proposed method.

Speed Sensorless Vector Control Method for an Industrial Drive System.

We propose a novel speed sensorless vector control method for induction motors, which is applicable to industrial drive systems.This method calculates the flux axis angular velocity and rotor speed of an induction motor from the induced voltages, without using any delay components. According to this method, the system can directly estimate an accurate motor speed, and precisely generate torque.In addition, this system can smoothly restart operation after an instantaneous power interruption.We show the validity of the proposed control method through several experiments.