Performance Of Sensorless Control Research Articles

Improved Full-Order Adaptive Observer for Sensorless Induction Motor Control in Railway Traction Systems Under Low-Switching Frequency

In the applications of medium- to high-power railway traction systems, the switching frequency and controller sampling rate are relatively low due to the requirements for low losses, high reliability, and limited processor power. These limitations greatly hinder the sensorless control of induction motors, especially in the high-speed operation range. In this paper, a full-order adaptive observer based on an improved discrete model is proposed, which significantly improves the system stability and control performance over the entire speed range. The feedback gain matrix of the presented control scheme is developed in a discrete time domain, ensuring that all the poles of the closed-loop observer are within the stable region. Moreover, a speed estimation mechanism based on Lyapunov’s approach is designed in the synchronous rotating reference frame to further improve the precision of speed observation. Rigorous simulation studies and experimental tests of a benchmark induction motor in railway traction system demonstrate that the improved adaptive observer achieves superior sensorless control performance over the conventional adaptive observer.

Quad Sampling Incremental Inductance Measurement Through Current Loop for Switched Reluctance Motor

Magnetic characteristics of a switched reluctance motor (SRM) determine the modeling accuracy, the performance of a position sensorless control, and the torque ripple reduction control. Due to double saliency structure and core saturation, the magnetic characteristics of SRM is dependent on both the rotor position and the winding current amplitude, which makes it difficult to measure the actual incremental inductance or flux linkage. This article presents the magnetic characteristics identification method. A quad current sampling technique is proposed to capture the derivative of the winding current at a specific rotor position and current amplitude. The flux linkage, co-energy, and torque are calculated from the obtained incremental inductance profile. The proposed method can be easily implemented on digital signal processor-based SRM drive without any extra circuit. The LCR meter and torque sensor measurements are provided to validate the proposed incremental inductance measurement method.

Sensorless-MTPA Control of Permanent Magnet Synchronous Motor Based on an Adaptive Sliding Mode Observer

Different from the traditional method of the interior permanent magnet synchronous motor (IPMSM), the sensorless maximum torque per ampere (MTPA) control scheme in this paper does not need two observers for rotor position and d-q axis inductances, respectively. It only needs an adaptive sliding mode observer (ASMO) based on the extended flux (EF) to realize double-loop control and MTPA operation simultaneously. The adaptive mechanism of rotor speed is designed to ensure stability of the ASMO. The rotor position and the difference between d-axis and q-axis inductances are obtained from the estimated EF to acquire the MTPA points when the position sensor of the IPMSM is absent. The proposed scheme is realized on a 20kW IPMSM where the sensorless control performance and the MTPA control performance are tested. The effectiveness of the proposed method is verified by the experiment results.

ILC-Based Voltage Compensation Method for PMSM Sensorless Control Considering Inverter Nonlinearity and Sampling Current DC Bias

Inverter nonlinearity and sampling current dc bias can cause harmonic distortion of estimated back electromotive forces (EMFs), and therefore results in position estimation error and degrades control performance of model-based sensorless techniques of permanent-magnet synchronous motors, especially in low speed region. In this paper, the effects of inverter nonlinearity and sampling current dc bias on back EMF estimation are analyzed. A voltage feedforward compensation method based on an iterative learning control (ILC) algorithm is proposed and it is used to eliminate the harmonics of estimated back EMFs and position estimation error, so as to improve the performance of sensorless control. Compensated voltages at different rotor positions are calculated online by the ILC algorithm and stored in a lookup table. The method does not depend on current polarity and inverter model. And it is simple and easy to implement. The effectiveness of the proposed compensation method is verified by experiments.

An Accurate Self-Commissioning Technique for Matrix Converters Applied to Sensorless Control of Synchronous Reluctance Motor Drives

The compensation of converters’ nonlinear voltage error is crucial in the encoder-less control of ac motor drives. In this paper, a new self-commissioning and compensation method is proposed for matrix converters (MCs). Similar to what done in the past for voltage source inverters, the MC voltage error is identified before the drive start and stored in a lookup table, later used for error compensation and accurate voltage estimate. Different from what observed in the past, the effect of parasitic capacitors on nonlinear voltage error of MCs in four-step current-based commutation is observed and studied. Eventually, this method is applied to the sensorless control of a synchronous reluctance motor drive, using the direct flux vector control concept. Experimental results are presented to validate the effectiveness of the proposed self-commissioning in improving the performance of sensorless control at standstill and low speed.

Initial Rotor Position Detection Method of SPMSM Based on New High Frequency Voltage Injection Method

A novel initial position detecting strategy of sensorless control for the surface-mounted permanent magnet synchronous motor is proposed, the scheme combines the virtual high frequency (HF) voltage pulsating injection method with the carrier frequency component method. In order to improve the sensorless control performance, this method adds the virtual HF rotation frame based on the traditional HF pulsating injection method. At the same time, the carrier frequency component signals are utilized to detect a magnetic pole. The simulation and experimental results show that the proposed method does not require proportion-integration (PI) regulation. The novel magnetic pole judgment method can effectively improve the detecting performance of sensorless control in the long algorithm execution time, complex process, etc. The experimental results verified the correctness of the strategy.

A Position Sensorless Control Strategy for SPMSM Based on an Improved Sliding Mode Observer

Due to chattering phenomenon, a low-pass filter (LPF) is commonly used to suppress chattering in conventional sliding mode observer (SMO). However, the phase lag caused by LPF will degrade the performance of sensorless control for SPMSM, especially in high-speed range. To solve this problem, an improved SMO (ISMO) is proposed in this paper, which adds the flux as a state variable based on conventional SMO. Then, the observer will filter out the chattering signal while observing the magnetic flux accurately.

High-Frequency Injection-Based Sensorless Control for a General Five-Phase BLDC Motor Incorporating System Delay and Phase Resistance

This paper investigates the sensorless control of a general Five-phase permanent magnet brushless DC (5Φ-BLDC) motor working at the low speeds. High frequency (HF) injection-based sensorless control is most popular, however, the system delay and stator resistance could deteriorate the sensorless control performance. In this paper, an HF model of 5Φ BLDCs at frequency-domain is primarily established as a replacement over the conventional static model, and an interpretation from the sinusoidal internal model is carried out to direct the sensorless control implementation. Accordingly, the measured d-axis HF current, which is typically neglected in the conventional method, is reused to demodulate the position angular information from the measured q-axis HF current. The proposed sensorless control is performed on a 5Φ BLDC drive, and experimental results confirm the effectiveness of this method while comparing its performance with the conventional method.

선박용 전기추진시스템을 위한 PMSM의 센서리스 제어성능에 영향을 미치는 SMO와 PI 제어기의 영향 분석

This paper analyzes some effects on sensorless speed control performance of a sliding mode observer (SMO) for building electric propulsion system of small ships using a permanent magnet synchronous motor (PMSM). An adaptive observer gain and switching function in the SMO are analyzed in detail to reduce the chattering phenomenon in estimated back electromotive force information. Furthermore, cascade low pass filter and PI controller gains are also investigated to progress speed sensorless control performance especially in low speed area. The results of simulations and experiments considering a 1.5 kW PMSM are provided to assure the effectiveness of the optimized SMO and controllers. The results show that the optimized SMO, cascade low pass filter, and controllers can give good speed sensorless control performances even when the PMSM operates at 5rpm.

Dynamic Performance of Estimator-based Speed Sensorless Control of Induction Machines Using Extended and Unscented Kalman Filters

Abstract This paper presents an estimator-based speed sensorless field-oriented control (FOC) method for induction machines, where the state estimator is based on a self-contained, non-linear model. This model characterises both the electrical and the mechanical behaviours of the machine and describes them with seven state variables. The state variables are estimated from the measured stator currents and from the known stator voltages by using an estimator algorithm. An important aspect is that one of the state variables is the load torque and, hence, it is also estimated by the estimator. Using this feature, the applied estimator-based speed sensorless control algorithm may be operated adequately besides varying load torque. In this work, two different variants of the control algorithm are developed based on the extended and the unscented Kalman filters (EKF, UKF) as state estimators. The dynamic performance of these variants is tested and compared using experiments and simulations. Results show that the variants have comparable performance in general, but the UKF-based control provides better performance if a stochastically varying load disturbance is present.

Sensorless Control of Brushless Doubly-Fed Generator Using Luenberger Observer Based Wind Energy Conversion Systems

<span lang="EN-US">This paper investigates the use of Luenberger observer for sensorless power control of brushless double fed induction machine (BDFM) in wind energy conversion systems, the control strategy for flexible power flow control is developed by applying flux oriented vector control (technique), In order to estimate the rotor speed, an adaptive algorithm based on Lyapunov stability theory will be design. Finally the analyzed and simulation results in MATLAB/ Simulink platform confirmed the good dynamic performance of this new sensorless control for BDFG based variable speed wind turbines.</span>

Improved Saliency-Based Position Sensorless Control of Interior Permanent-Magnet Synchronous Machines With Single DC-Link Current Sensor Using Current Prediction Method

This paper presents an improved saliency-based position sensorless drive of an interior permanent-magnet synchronous machine (IPMSM) with a single current sensor, used for low cost applications. The phase current, reconstructed from a dc-link current, shows a reconstruction error resulted from the difference of the sampling point from that of a full current sensor drive. This reconstruction error results in degradation of the overall sensorless control performance. In this paper, we analyze the impact of the reconstruction error depending on the injection frequency for a high frequency voltage signal injection sensorless control. Based on this analysis, we propose an improved position sensorless drive that employs a new current reconstruction method. In order to minimize the reconstruction error, the proposed current reconstruction method predicts the dq -axis currents with the same sampling point as a full current sensor drive. Several experimental results are provided to verify the analysis of the reconstruction error and the proposed method's improved sensorless control performances.

Rotor position estimation scheme with harmonic ripple attenuation for sensorless controlled permanent magnet synchronous motors

To achieve high-performance sensorless control of permanent magnet motors with non-sinusoidal back electromotive force (EMF), an improved sliding mode observer (SMO) adopting synchronous rotating low-pass filter (SRLPF) is proposed. The SRLPF is utilised to reduce the back-EMF harmonics and extract the fundamental component. Different from the traditional rotor position observer, the proposed observer can calculate the rotor position with the back-EMF fundamental component. Owing to the decrease in the influence of non-sinusoidal back-EMF, the estimated rotor position harmonic ripple error can be greatly reduced. Then, the high estimated accuracy and excellent sensorless control performance can be obtained. In addition, the proposed strategy is easy for implementation. With the comparison between the traditional SMO and the proposed observer, the experiments of the system steady-state error, the speed tracking performance, and the disturbance rejection ability in the speed range from 60 r/min to the rated speed 750 r/min are presented. The validity of the proposed method is conformed.

Extended Kalman Filter for Sensorless Fault Tolerant Control of PMSM with Stator Resistance Estimation

<p><span>This paper aims to provide a high performance sensorless control based on an Extended Kalman Filter (EKF) applied to fault-tolerant PMSM drive system with stator-resistance estimation. It proposes a fast method of fault switches detection in the power converters. The considered drive is composed of three phases PMSM and a four leg three phase’s inverter when the fourth is the redundant leg. After a short-switch fault occurrence, the redundant leg replaces the faulty leg. The simulation results verify that the proposed control method and the fault tolerant inverter ensure the high reliability and continuously operation of the sensorless vector control PMSM system under inverter fault.</span></p>

Position sensorless control of high-speed brushless pm motor based on an improved sliding mode observer

With the advantages of simplicity and robustness, the position estimation method based on a sliding mode observer (SMO) has been widely used in brushless PM motor sensorless control such as turbo-molecular pump (TMP). Due to the chattering phenomenon of a typical sliding mode algorithm, a low-pass filter is necessary to suppress the estimated back electromagnetic force (back-EMF) harmonics, which results in phase lag. It would degrade the performance of sensorless control in the high-speed range. On the one hand, the phase lag increases position error as the motor accelerates. On the other hand, the harmonics induced by the nonlinearity of inverter are hardly to be suppressed by low-pass filters since the signal frequency varies with rotor speed. In order to solve this problem, an improved sensorless control method is proposed. Instead of low-pass filters, a Second-Order generalized integrator (SOGI) is used to get the fundamental component of the back-EMF with minimal phase lag. Besides, a tracking differentiator (TD) replaces the backward difference algorithm to estimate speed and filter position. At last, it is tested on a magnetically levitated TMP and the experimental results verify the validity and reliability of the proposed control method.

Sensorless Control of IPMSM Drive using EKF with Electromegnetic Noise Effect

This paper proposes a new move toward to assess the performance of sensorless control of interior permanent magnet synchronous motor (IPMSM) drive along with electromagnetic noise effect by using EKF. Normally in rotary condition, rotor position and speed estimation of IPMSM drive are drawn through an Extended Kalman Filter (EKF) algorithm by measuring its voltages and currents of the stator. The main drawback in developing EKF is it may not proficient to consider the effect of electromagnetic noise which is mainly produced during the time of different speed ranges. Owing to this reason this may cause to vary the motor flux linkages which are significant to find the rotor position and speed by EKF method will give approximate results. To carry on this process, we present the simulation results for sensorless speed control of IPMSM drive by using EKF algorithm with the incorporation of a noise signal which is corresponding to the frequency of electromagnetic noise signal using MATLAB/Simulink software. The armature current, rotor position, and speed estimation are analyzed under this noise signal effect and the effectiveness of the EKF for sensorless control of IPMSM drive is observed.

A Back-EMF Estimation Error Compensation Method for Accurate Rotor Position Estimation of Surface Mounted Permanent Magnet Synchronous Motors

This paper proposes a back electromotive force estimation error compensation method for accurate rotor position estimation of surface mounted permanent magnet synchronous motors. When estimating the rotor position of surface mounted permanent magnet synchronous motor sensorless drives, a direct current offset error component occurs in the voltage sensor. As a result, the rotor position is distorted and the sensorless control in surface mounted permanent magnet synchronous motor is degraded. In addition, the dq-axis voltages in the synchronous reference frame have the direct current offset error component, ripples compared with the motor frequency under the distorted rotor position. In this paper, the effects of the direct current offset errors are analyzed based on the synchronous reference frame phase locked loop. To remove this direct current offset error component, a d-axis voltage is converted into a synchronous reference frame again to compensate. In other words, it is a dual synchronous coordinate conversion compensation method. The compensator utilizes a proportional-integral controller that compensates by estimating the direct current offset error component. The proposed method is useful for the improvement of surface mounted permanent magnet synchronous motor sensorless control and operating performance. The effectiveness of the proposed algorithm is verified through PSIM simulation and experimental results.

Carrier signal injection‐based sensorless control for permanent magnet synchronous machine drives with tolerance of signal processing delays

In the case of high precision A/D converters, carrier signal injection based position estimation methods can adopt a relatively higher injection frequency (>1/10 pulse width modulation (PWM) switching frequency), which can lead to enhanced system bandwidths. However, simultaneously, signal processing delay effects (e.g., PWM duty ratio updating delay, etc.) become prominent, resulting in large phase shifts of carrier currents. On the other hand, the high frequency (HF) resistance effects may also be enlarged. Consequently, large oscillating position estimation errors will arise for the pulsating injection method due to carrier signal distortions induced by the delay and HF resistance effects. In order to suppress the undesirable position errors, based on the theoretical analyses, a new compensation strategy of maximizing the useful inductive saliency part and minimising the resistive saliency components using a PI regulator is proposed. The proposed position error suppression method is very easy and simple to implement, and moreover can significantly improve the sensorless control performance. Furthermore, the similar compensation strategy can also be applied for the position error compensation for rotating injection method as will also be discussed in this paper. Finally, the theoretical analyses and compensation effectiveness are validated by experiments on a laboratory interior permanent magnet machine.

Improved Pulsating Signal Injection Using Zero-Sequence Carrier Voltage for Sensorless Control of Dual Three-Phase PMSM

The sensorless control performance of pulsating carrier signal injection employing zero-sequence voltage for dual three-phase (DTP) permanent magnet synchronous machine (PMSM) drives is investigated in this paper. This method has the synergy of high bandwidth of zero-sequence voltage method and high position estimation accuracy of pulsating injection strategy. However, such a method for single three-phase PMSM exhibits large oscillation in position estimation error due to undesirable harmonic components in the zero-sequence carrier voltage, and the existing compensation methods usually require complex structures or intensive offline measurements. As for DTP-PMSM, the undesirable harmonic components for the pulsating injection can be suppressed with an optimum phase shift between the two injected high-frequency signals. Besides, a new simple measurement method of zero-sequence carrier voltage is proposed with only one voltage sensor placed between the two isolated neutral points. As a result, the rotor position estimation accuracy can be significantly improved. The experimental results verify the effectiveness of the proposed method for DTP-PMSM.

Real time implementation of a new fuzzy-sliding-mode-observer for sensorless IM drive

PurposeThe purpose of this paper is to improve the performance of sensorless vector control of induction motor drives by developing a new sliding mode observer for rotor speed and fluxes estimation from measured stator currents and voltages and estimated stator currents.Design/methodology/approachIn the present paper, the discontinuity in the sliding mode observer is smoothed inside a thin boundary layer using fuzzy logic techniques instead of sign function to reduce efficiently the chattering phenomenon that affects the rotor speed.FindingsThe feasibility of the proposed fuzzy sliding mode observer has been verified by experimentation. The experimental results are obtained with a 1 kW induction motor using a dSPACE system with DS1104 controller board showing clearly the effectiveness of the proposed approach in terms of dynamic performance compared to the classical sliding mode observer.Practical implicationsThe experimental results of the whole control structure highlights that this kind of sensorless induction motor drive can be used for variable speed drive in industrial applications such as oil drilling, electric vehicles, high speed trains (HSTs) and conveyers. Such drives may work properly at zero and low speed in both directions of rotation.Originality/valueBoth the proposed speed observer and the classical sliding mode observer have been developed and implemented experimentally with other adaptive observers for detailed comparison under different operating conditions, such as parameter variation, no-load/load disturbances and speed variations in different speed operation regions.