Sensorless Vector Research Articles

A new robust sensorless vector-control strategy for wound-rotor induction motors

ABSTRACT Aim of this study is to investigate a sensor-less speed-observer with the principles of vector control for the industrial applications of Wound-Rotor Induction Motors (WRIM). The proposed estimation method is based on a simple topology to efficiently predict the rotor-speed signal with the aid of the phase axes relations of the adopted motor and using the flux orientation scheme with the indirect type (IRFOC). To effectively verify the efficacy of the presented sensor-less control system, overall results are carried out. The realised analysis validates the proposed estimation method for the rotor-speed of WRIM, which ensures its capability for sensor-less vector control methodology of the adopted system.

Sensorless vector control of SCIG-based small wind turbine systems using cascaded second-order generalized integrators

In this paper, a novel sensorless control scheme for SCIG-based wind turbine systems, which utilizes cascaded second-order generalized integrators (SOGIs), is proposed. The DC offset and harmonics in the estimated rotor flux can be significantly reduced since the cascaded SOGI behaves like an adaptive filter. The stator frequency, which is regarded as the tuning frequency of the SOGI, is estimated from the amplitude differences among the cascaded SOGI outputs by a PI controller. Simulation and experimental results have verified the validity of the proposed sensorless scheme under wind speed variations.

Sensorless Control of a Tubular Oscillatory LPMSM based on MARS and Deadbeat Current Predictive Control

In the vector control system of the tubular oscillatory linear permanent magnet (PM) synchronous motor (LPMSM), it is difficult for traditional mechanical sensors to accurately obtain the feedback information under harsh conditions. In this work, a speed sensorless vector control system is designed and applied to the tubular oscillatory LPMSM which adopts the model reference adaptive system (MRAS), and the deadbeat current predictive control (DCPC) is also adopted to replace the traditional PI current loop to establish the coordination controller, which overcomes the difficulties of global optimization and PI control parameter setting. And the method is proved by the simulation results and it gets better dynamic performance.

An Improved Sensorless Vector Control Method for IPMSM Drive with Small DC-Link Capacitors

In this paper, an improved sensorless vector control method for an interior permanent magnet synchronous motor (IPMSM) drive with small DC-link capacitors is proposed. First, a fast sliding-mode observer was applied, to enlarge the observer bandwidth. Then, an improved estimator based on a proportional integral resonant controller was designed for the estimate speed shaping, which means the actual speed can be tracked. This not only reduces the position estimate error, but also enhances the grid power factor and suppresses the input current harmonics. Simulation and experiments were conducted on a sensorless IPMSM drive system with a small film capacitor. The effectiveness of the proposed estimation method was verified by the simulation and experimental results. The estimated error was reduced and the grid current harmonics satisfy the requirements of EN61000-3-2.

Stator Flux Based Model Reference Adaptive Observers for Sensorless Vector Control and Direct Voltage Control of Doubly-Fed Induction Generator

A position sensorless operation of a doubly-fed induction generator (DFIG) is desired from considerations of cost, maintenance, cabling, and reliability. This article proposes two stator flux based model reference adaptive observers (SF-MRAOs) for the estimation of the rotor speed and position in a stand-alone DFIG. The cross product of the reference and estimated stator flux linkage vectors is fed as controller input in the existing method, thereby, making the observer model nonlinear. The first proposed method, which is based on notch filtering, offers a performance comparable to that of the existing method while reducing the number of voltage and current sensors required. The second proposed method linearizes the error input to the controller, making the controller design straight forward, and also leading to superior performance than the existing methods. The linearized SF-MRAO is shown to work successfully with good dynamic performance in vector control of a stand-alone DFIG. This article also shows that the proposed linearized SF-MRAO can be employed for obtaining the rotor current angle in direct voltage control of a stand-alone DFIG. Simulation and experimental results are presented from a laboratory prototype of a 10-hp DFIG coupled to a squirrel-cage induction motor. The sensitivity of the performance of the proposed linearized SF-MRAO to variations in machine parameters is also studied theoretically and experimentally.

Sensorless speed control of SPIM using BS_PCH novel control structure and NNSM_SC MRAS speed observer

This paper propose a novel Port Controlled Hamiltonian_Backstepping (PCH_BS) control structure with online tuned parameters, in combination with the modified Stator Current Model Reference Adaptive Syatem (SC_MRAS) based on speed and flux estimator using Neural Networks(NN) and sliding mode (SM) for sensorless vector control of the six phase induction motor (SPIM). The control design is based on combination PCH and BS techniques to improve its performance and robustness. The combination of BS_PCH controller with speed estimator can compensate for the uncertainties caused by the machine parameter variations, measurement errors, and external load disturbances, enables very good static and dynamic performance of the sensorless drive system (perfect tuning of the speed reference values, fast response of the motor current and torque, high accuracy of speed regulation) in a wide speed range, and robust for the disturbances of the load, the speed variation and low speed. The proposed sensorless speed control scheme is validated through Matlab-Simulink. The simulation results verify the effectiveness of the proposed control and observer.

Speed Sensorless Vector Control of a PMSM Using MRAS based on Sugeno Fuzzy Inference System Adaptation Mechanism

Speed Sensorless Vector Control of a PMSM Using MRAS based on Sugeno Fuzzy Inference System Adaptation Mechanism

Performance Improvement of Sensorless Vector Controlled Induction Motor Drive for Medium Power Applications

This paper deals with sensorless vector controlled induction motor in which torque pulsations are reduced with improved input of induction motor. In proposed technique two multi winding transformers are used for generation of 18 sinusoidal signals given to rectifier unit and the rectifier output given as input to 9 level multi level inverter. In this proposed technique gating signals to the inverter switches will be provided through space vector pulse width modulation which considers speed as reference. This configuration was simulated in MATLAB/Simulink.and the simulation results are presented here with improvement in reduction of THD.

Utility Grid Interfaced Solar WPS Using PMSM Drive With Improved Power Quality Performance for Operation Under Abnormal Grid Conditions

Owing to the intermittency issue associated with renewable energy sources, a solar photovoltaic (PV) array fed grid interfaced encoder-less permanent magnet synchronous motor (PMSM) based solar water pumping (SWP) system is presented in this paper. The grid integration enables a continuous water flow regardless of available solar insolation. However, it has been observed that the grids in developing and underdeveloped countries are mostly weak. Moreover, as SWP systems are typically established at remote locations, which are generally the grid radial ends, therefore, prone to various grid abnormalities. Such abnormalities affect the SWP system performance. Therefore, a hybrid multi-resonant generalized integrator-frequency locked loop (HMRGI-FLL) control structure is presented in this paper to deal with the abnormalities in grid voltage and makes the SWP system operational even under weak grid condition. The proposed structure not only rejects the dc-offset but it also eliminates the dominant lower order harmonic with its selective harmonic elimination capability. A boost converter is used on the grid side to facilitate the power transfer from the grid. In condition of grid failure, the output water flow is regulated in accordance with available solar insolation. The speed of the PMSM is regulated using sensor-less vector control. Performance of the proposed system is experimentally validated using a laboratory prototype under varying solar insolation, during grid failure, during voltage sag, voltage swell, and distorted grid voltage conditions.

Research on sensorless control method of permanent magnet synchronous motor based on iterated cubature Kalman filter.

Aiming at the problems of high cost, increased volume, low reliability, and environmental interference caused by sensor installation on permanent magnet synchronous motor, estimation method for motor speed and rotor position is proposed based on iterated cubature Kalman filter algorithm and applied to permanent magnet synchronous motor sensorless control. First, discrete mathematical model of permanent magnet synchronous motor in α-β coordinate system is established. Then, based on cubature Kalman filter and iterated cubature Kalman filter, simulation model of sensorless vector control system with dual closed-loop of permanent magnet synchronous motor speed and current is established. Also, simulation verification of two working conditions with given rotation speed and load is carried out. Finally, hardware experimental verification platform is built based on TMS320F28335 chip. Both simulation analysis and experimental results show that iterated cubature Kalman filter application to sensorless control of permanent magnet synchronous motor demonstrates good anti-load variation interference, stable motor operation, high motor speed and rotor position estimation accuracy, which suits the application with high requirement for precise motor control and mean important reference value and promotion significance.

Analysis and Control of Weak Grid Interfaced Autonomous Solar Water Pumping System for Industrial and Commercial Applications

The limited hours of availability and fluctuating behavior of solar insolation severely impact the reliability of solar photovoltaic (PV) integrated system. This article proposes a new topology of grid interactive solar water pumping (SWP) system to deal with the issue of frequent variation in insolation, related to solar power generation. Such intermittency affects the system performance and makes it unreliable for industrial and commercial applications. In contrary to the conventional voltage source converter, the proposed topology utilizes a reduced switch Vienna rectifier for utility grid integration. Although utility grid integration appears to be a viable solution, however, as most of the grid in underdeveloped and developing countries are generally weak, such integration faces the additional power quality challenges, like voltage sag, voltage swell, dc offset, harmonics distortion, etc. To deal with the problems associated with weak grid condition, a novel mix multiresonant generalized integrator (MMRGI) control structure is proposed in this article. Along with the selective harmonic elimination capability, the proposed MMRGI structure offers a high dc offset and higher-order harmonic rejection capability. The proposed control approach is also capable of effectively extracting the balanced positive sequence components from unbalanced distorted grid voltages, thereby, keeping the grid currents balanced. The proposed system uses a sensor-less vector control technique to drive the permanent magnet synchronous motor used for rotating the pump. A perturb and observe algorithm is used for optimum power harvesting from the solar PV array. A prototype of proposed system is developed and performance is investigated experimentally using a digital signal processor DS1202.

Assessment of the influence of interference on the sliding mode observer

The article presents the results of studying the effect of interference on the sliding mode observer. The effect of interference in the lines feeding the engine is evaluated. The measured interference is present in the current signal. The operation of a sliding observer of the position and speed of the rotor of a permanent magnet synchronous motor is described. This observer is used as part of a sensorless vector drive control system. The presented version of the motor state observer is implemented by creating a model in the Matlab Simulink software package and tested on the bench using a 200W motor. The aim of the work is to develop an observer who is resistant to drive parameter changes.

Speed sensorless control strategy for six‐phase linear induction motor based on the dual reduced‐dimensional serial extended Kalman filters

This study proposes a speed sensorless vector control strategy for the six-phase linear induction motor (SPLIM) based on the dual reduced-dimensional serial extended Kalman filters (DRDSEKFs). Firstly, the low-order mathematical model of SPLIM is obtained according to the equivalent transformation of primary voltage, current and flux components in the stationary coordinate system. Then, the state equation is derived and the speed estimation based on the five-dimensional extended Kalman filter (EKF) is realised. To reduce the computation cost and improve the accuracy of speed estimation, a DRDSEKFs algorithm is proposed, with one two-dimensional EKF and one three-dimensional EKF operating serially in every control period. As the real-time performance of the algorithm is guaranteed, it is possible to overcome the hysteretic nature of the traditional EKF and improve the dynamic estimation performance. Simulations and experiments show that the proposed sensorless control strategy is feasible and effective.

Comparison of high‐order and second‐order sliding mode observer based estimators for speed sensorless control of rotor‐tied DFIG systems

In this study, a sensorless vector control for the rotor-tied doubly fed induction generator (RDFIG) is proposed in the grid-connected mode. The proposed sensorless vector control method includes a slip speed/angle estimator which is based on the association of the high-order sliding mode observer (HOSMO) with a phase-locked loop (PLL). In addition, an extensive comparison between the PLL-based HOSMO estimator and the PLL-based second-order sliding mode observer (SMO) estimator is also presented. The Lyapunov stability criterion is used to determine both observer gains to allow their convergence in finite time. Both the proposed HOSMO and the SMO use the three-phase stator current and back-electromotive force (EMF) as state variables which enable the start of the estimation even before the machine is connected to the grid. The proposed HOSMO takes into account the dynamics of the back-EMF space vector. The PLL is used to extract the estimated slip speed/angle from the estimated back-EMF. The performance of the proposed sensorless vector control strategy is validated experimentally with a 5.5-kW custom-designed RDFIG on a test bench based on the National Instrument (NI) PXIe-8115 real-time controller.

Inertia Estimation and Speed Loop Auto-Tuning for IPMSM Self-Commissioning

This paper presents a practical procedure regarding inertia estimation and speed loop auto-tuning for sensorless interior permanent-magnet synchronous motor (IPMSM) drives. In many applications, well-tuned speed controller is essential to enable dynamic and stable drive operations. However, high-performance speed controller design requires system parameters such as inertia which are unknown at the beginning of drive commissioning. Manual trial-and-error tuning is unattractive due to its blind, lengthy, non-optimal, and potentially unsafe nature. On the other hand, model-based tuning through inertia estimation has unique challenges at this step of self-commissioning. Determining the test torque for a safe and reasonably short test in inertia estimation is a real practical problem because the total inertia can be in wide range in different mechanical systems. Furthermore, feedback controllers are not usable to automatically determine the test torque due to unknown motor parameters. As a solution, this paper proposes an automated test torque selection procedure. Then it identifies the inertia and lastly tunes the speed controller using the identified parameter. Overall, a fully automated speed-loop auto-tuning method is proposed which aims minimal operator involvement. The findings are experimentally verified on an IPMSM drive. In addition, the proposed method can easily be extended to different motor types and sensored or sensorless vector control strategies.

A new high-response self-balancing sensorless control system of induction motor for weft accumulator

The high-response and self-adaptive yarn delivery system used in weft accumulator is a critical component for improving the efficiency and quality of textile machinery. However, the existing drive system in the weft accumulator has problems such as slow start-up and slow speed-tracking responses, giving difficulties in achieving a high-efficient yarn delivery of the textile machinery. In this paper, a high-response self-balancing sensorless integrated control system of the induction motor for weft accumulator is proposed. Firstly, to enable the motor to start and respond adaptively and quickly to the number of yarn control loops and the speed control of the external equipment, a high-response sensorless vector control system for induction motor based on improved model reference adaptive control(MRAC) is proposed. Secondly, to achieve a high-response adaptive tracking performance of yarn input and output numbers and spool shaft speed, a self-balancing control strategy based on optical electromechanically integrated closed-loop control is proposed. For proving the effectiveness of the proposed scheme, a corresponding test platform was constructed for testing and validation. It can be observed from the results that the system designed in this paper has fast starting speed and better speed tracking performance, satisfying yarn delivery requirements at different speeds with high-response and adaptability.

Evaluation of an STSMO‐based estimator for power control of rotor‐tied DFIG systems

In this study, a sensorless vector control strategy of a rotor-tied doubly fed induction generator (RDFIG) system based on the association of the phase-locked loop (PLL) estimator and the super-twisting sliding mode observer (STSMO) is proposed and analysed. The proposed sensorless control strategy utilises the stator current and the back-electromotive force (EMF) as state variables. The advantage of the proposed sensorless control strategy is that the estimation process is conducted before the machine is connected to the grid. The slip angle/speed is extracted from the estimated back-EMF space vector by using a PLL. The parameters of the STSMO are selected such that the Lyapunov stability criteria are fulfilled and that fast response is achieved. The robustness of the proposed position/speed sensorless control strategy is validated through steady state and dynamic experimental measurements on a 5.5 kW custom-designed grid-connected mode RDFIG test bench based on a National Instruments PXIe-8115 controller.

Speed Sensorless Vector Controlled SMPMSM Drive Based on Modified MRAS with Single Current Sensor

New speed estimation technique is proposed in this paper. This is used to formulate a single current sensor-based vector controlled surface mounted (SM) permanent magnet synchronous motor (PMSM) drive. A combination of dc-link measurement and model reference adaptive scheme (MRAS) is adopted for the implementation of speed sensorless control. Unlike existing MRAS that make use of both dq-axes currents/flux/voltages, the proposed approach has simplified adaptive mechanism based on q-axis current only. The proposed technique is less complex, stable at low speed, less expensive. The proposed technique is simulated in MATLAB/Simulink and validated experimentally through dsPIC MCHV-2 based laboratory prototype.

Sensor-less vector control of induction motor at low-speed operation using modular multilevel converter

ABSTRACTModular Multilevel Converter (MMC) is widely known as one of the most promising topologies for high power medium voltage application. However, MMC is still limited when it comes to Variable Speed Drive (VSD) applications. The reasons behind this is the large fluctuations in the submodules capacitor voltages during low-speed constant torque operation. Thus, the feasibility of sensor-less vector control of MMC based variable speed drive is considered as a difficult task. This paper proposes a novel speed observer for MMC-based VSD suitable for low-speed operation. Speed estimation is carried out by using the stator currents and the input voltages. A discrete model where the rotor parameters do not change during a short sampling time is considered. An extensive simulation is carried out for verifying the closed loop operation of the proposed speed sensor -less MMC-based VSD.

Sensorless Control of Permanent Magnet Bearingless Synchronous Motors Using Online Parameter Identification

A novel rotor position estimation scheme using online parameter identification based on grey model is suggested in this paper, which will meet the need of sensorless control for permanent magnetism bearingless synchronous motor (PMBSM). The scheme is computationally simple and does not rely on the motor parameters. And then, the sensorless vector control system of PMBSM is set up based on this position estimation approach. The results of simulation and experiments show that the proposed method is capable of precisely estimating the rotor space position and is able to achieve stable suspension under the bigger disturbance.