Papers by Keyword: Sensorless

Abstract: Based on the characteristics of the back electromotive force (back-EMF), the rotor position information would be detected. Hence, the main theme of this paper is to design a practical approach to detect the zero cross point (ZCP) of back-EMF through virtual neutral voltage for sensorless brushless direct current (BLDC) motor drives. In contrast to conventional methods, the real neutral voltage of motor is not needed. In order to compensate the phase delay of the back-EMF due to low-pass filter (LPF) under different speeds, a voltage-controlled phase shifter, consisted of hysteresis comparator and voltage-controlled resistor (VCR), is proposed in this paper. The detail circuit model is introduced and some experimental results obtained from a sensorless prototype are shown to confirm the practicality of proposed senosorless drive method.

Abstract: This paper proposes a sensorless procedure to estimate the induction motor speed and the dependable heat contents of the stator and rotor sides. The proposed procedure is based on the electrical models of a three phase Induction Motor (IM). The motor electrical models for normal and abnormal will be discussed and a technique is introduced for accommodating frequency dependent skin effect of the rotor resistance using a simple proposed speed estimation algorithm. The electrical models are customized from the positive and negative sequence networks. The speed detection is based on the rotor parameters slip dependent. The models are then used to analyze different operating conditions of the motor. Two thermal motor protection schemes are suggested. The first scheme is dependent on the stator side while the other scheme is developed for rotor side. The Matlab software is used for this purpose to emulate efficiently the proposed estimation procedures through a complete motor modeling which is fed from the power grid. Finally, the results provide the motor performance characteristics which involve current, torque, speed and stator/rotor temperature versus time for numerous operating conditions. It is concluded that the proposed sensorless procedure is efficient to protect the induction motors against abnormal starting as well as the overheating on either stator or rotor sides. Also, the proposed sensorless estimation for speed and temperature is reliable for submersible motor applications. The proposed schemes can be considered as costless preventive maintenance procedure.Index Terms: induction motor, slip dependent, sensorless, thermal model, abnormal operating conditions.

Abstract: Torque ripple and resulted acoustic noise and vibration are the main disadvantages of brushless DC (BLDC) motor drives. In this study, One-Cycle Control (OCC) is developed for current regulation of brushless DC (BLDC) motor drive as a unified constant-frequency integration control strategy. Employing one-cycle control strategy reduces high frequency torque ripple of conventional hysteresis current controllers leading to lower acoustic noise and vibration in the drive. To enhance reliability and reducing drive cost, an improved rotor position estimation technique is implemented. OCC strategy and sensorless method are realized using a low-cost general-purpose AVR microcontroller (Atmega8). It is shown that torque ripple, acoustic noise and vibration are reduced via OCC method comparing to conventional hysteresis control strategy. Computer simulations and experimental results with a 375W, 16 poles BLDC motor, demonstrate improved behavior of developed sensorless BLDC drive operation.

Abstract: In this paper, to eliminate the mechanical sensors, a sliding-mode observer is designed to identify the speed of permanent magnet synchronous motor (PMSM) based on a field-oriented control system. The results of simulation by Simulink indicate that the speed could be estimated and adjusted precisely. The three-phase current and torque of the motor also have a good dynamic response.

Abstract: Considering the issue that it is difficult to precisely extract the rotor information within the full scope of speed for PMLSM sensorless driving system,this paper proposes a convenient position estimation algorithm based on a new type of closed-loop observer to adapt the characteristics of wide range of linear motor speed variation.To accurately estimate the rotor position information for PMLSM system with speed varying from launching to full speed,the new algorithm is like following: based on the three-phase stationary coordinate system of PMLSM voltage model, deduce quadrature-axis current differential equations from its rotating coordinate system(d-q axis)voltage model through by Parker transformed. moreover,get the actual alternating axis current by current measuring circuit. By driving a closed-loop observer through difference between the two current differential to input and process the difference of magnetic polo position by PI algorithm, then estimate the position of the motor.Simulation results show that the convenient algorithm with position closed-loop observer can estimate the location of the motor relatively accurately in full range of speed.

Abstract: This paper will introduce the sensorless vector control system of permanent magnet synchronous motor,it adopts the PLL structure to correct motor back electromotive force for the motor rotor speed/position estimation and vector control algorithm to realize speed and current loop control of PMSM.This paper established a mathematical model of the PMSM,design of system software and hardware,the principle of speed/position estimation method and simulation of system in Matlab/Simulink.Finally,it introduces the experiment of whole system in TMS320F2808-based PMSM experiment platform,the simulation and experimental result verify feasibility,fast response and practicability of the system.

Abstract: According to the chattering problem in the traditional sliding mode observer of the position sensorless control of brushless DC motor, a novel quasi sliding mode observer for rotor position estimation was proposed, which took the error between the actual and estimated currents as sliding surface and tracked the actual rotor position according to the mathematical relationship of back EMF and speed of the motor. Then the sensorless control system of the brushless DC motor based on the novel sliding mode observer was designed. Simulation results showed that the novel sliding mode control method could improve the rotor position estimation accuracy and effectively suppress the chattering problem to enhance the robustness of system.

Abstract: This paper proposes a novel sliding-mode model reference adaptive system (MRAS) observers for speed observer in a sensorless controlled doubly fed induction generator (DFIG) aligned with the stator flux. In the strategy, two stator flux models with different structure are used. The stator flux voltage model without including rotor position item is used as reference model, and the stator flux current model including rotor position item as adjustable model. A slide-mode surface is formulated from the errors between the two models, and the rotor speed estimation can be obtained by a sliding mode algorithm. Meanwhile the one order inertial link is used to avoid suffering from integrator drift effects in voltage model. Simulation results confirm the validity of the approach.

Abstract: A novel sliding mode observer(SMO) of PMSM(permanent magnetic synchronous motor) was presented, which estimated the rotor position and angular velocity accurately.The proposed SMO substitutes a sigmoid function for the conventional signum function with a variable boundary layer which is changed according to the rotational velocity.The dependence to motor parameters and chattering effects that is commonly found in signum function using for the switching function were overcome.By combining the model of PMSM under d-q coordinate,the convergence condition of observer was deduced.The convergence was verified by the Lyapunov theory.Simulation results show that the rotor position and velocity can be observed accurately,and also has good dynamic performance and robustness.

Abstract: In this paper, a rotor flux based variable-structure model reference adaptive system (MRAS) observers is proposed for speed observer in a sensorless controlled doubly fed induction generator (DFIG) aligned with the stator flux. In the strategy, two rotor flux models with different structure are used. The rotor flux voltage model without including rotor position item is used as reference model, and the rotor flux current model including rotor position item as adjustable model. A slide-mode surface is formulated from the errors between the two models, and the rotor speed estimation can be obtained by a sliding mode algorithm. Meanwhile the one order inertial link is used to avoid suffering from integrator drift effects in voltage model. Simulation results confirm the validity of the approach.