Sensorless Synchronous Reluctance Research Articles

Dead-Time Compensation Using ADALINE for Reduced-Order Observer-Based Sensorless SynRM Drives

The inverter dead time effect is non-negligible for the control performance of sensorless synchronous reluctance motor (SynRM) drives at low speeds. In this paper, a reduced-order observer-based sensorless control method for SynRM drives combined with the adaptive linear neurons (ADALINE)-based dead-time compensation is proposed. The reduced-order observer-based sensorless control method is presented, for which is parameter tuning is easy. On this basis, the dead-time compensation strategy using ADALINE filters is proposed to reduce the voltage harmonics effect on the estimation performance of the reduced-order observer. With ADALINE filters, the sixth current harmonic can be successfully filtered out by compensating the voltage directly or fitting the current to compensate the voltage. In this way, the low-speed estimation performance of the reduced-order observer is improved. The effectiveness of the proposed method is verified on a 3 kW SynRM experimental platform.

Variable-Angle Random High-Frequency Voltage Injection Strategy with Cross-Saturation Effect Compensation for Sensorless Synchronous Reluctance Motor Drives

There are usually noise problems when the position sensorless control of a synchronous reluctance motor (SynRM) is carried out by high-frequency (HF) signal injection method. Due to the special structure, the cross-saturation effect of the SynRM is particularly serious, resulting in reduced position observation accuracy. In this paper, a variable-angle random HF voltage injection strategy with cross-saturation effect compensation is proposed for position sensorless SynRM drives. Random number generation based on the chaotic mapping method is used to generate random HF voltage signals with different frequencies for injection; the current power spectral density (PSD) distribution is extended and the HF noise can be reduced. A control strategy based on variable-angle square-wave injection is proposed to suppress the cross-saturation effect. By measuring the position error curves of different loads off-line and polynomial fitting the curves, the position error is achieved by combining with the corresponding signal demodulation algorithm. The proposed method does not require additional hardware resources and can maintain high control accuracy and robustness. Finally, the effectiveness of the proposed sensorless control strategy is verified on a 3 kW SynRM experimental platform.

Improved Current Regulators for Sensorless Synchronous Reluctance Motor

Improved Current Regulators for Sensorless Synchronous Reluctance Motor

Rotor Position Error Compensation in Sensorless Synchronous Reluctance Motor Drives

A new approach to compensate rotor position errors caused by parameter mismatching in model-based sensorless synchronous reluctance (SynchRel) motor drives is presented in this article. According to the proposed approach, the error in estimating the rotor position is detected by injecting some low-frequency current signals and adjusting the estimated rotor angular position through a gradient descent algorithm until minimizing the ripple generated on the estimated rotational speed. A rotor position correction can be fully online accomplished coping with saturation and cross saturation effects, as well as with unmodeled phenomena and unpredictable variations of the stator resistance with the temperature. The correction procedure can be accelerated by starting from an approximated correction table, which can be offline built using the same technique. The proposed approach neither needs additional current or voltage sensors nor motor design modifications, thus providing an inexpensive mean to improve the control performance and robustness. Although originally conceived to deal with back EMF-based sensorless control techniques, the correction procedure can be extended to other model-based sensorless SynchRel motor drives.

Hybrid Pseudorandom Signal Injection for Position Sensorless SynRM Drives With Acoustic Noise Reduction

The extra acoustic noise caused by the high-frequency (HF) signal injection imposes restrictions on its extensive applications for sensorless synchronous reluctance motor (SynRM) drives. To attenuate the undesired acoustic noise further, a hybrid pseudorandom (PR) signal injection scheme is proposed in this article. The hybrid PR signal injection is implemented by injecting square wave signals chosen in a random manner from a set of signals having either different frequencies or phases from each other. The optimal assembly of hybrid PR signals is designed via current power spectral density (PSD) analysis, aiming at reducing acoustic noise as much as possible. In this way, the proposed scheme achieves success in a massive acoustic noise reduction by means of completely eliminating the discrete harmonics of the current PSD and distributing the current PSD to a wider range. Besides, the low-pass filters used to separate the fundamental frequency component from injected HF components of currents could be eliminated because no discrete harmonics at injected frequencies exist with the proposed hybrid PR signal injection. The validity and superiority of the proposed sensorless control scheme are verified on a 3-kW position sensorless SynRM drive platform.

Grid-Tied Battery Integrated Wind Energy Generation System With an Ability to Operate Under Adverse Grid Conditions

An efficient control of a grid integrated microgrid with wind energy generating system (WEGS) and a battery storage, is implemented in this work. The quality of power injected to the utility is deteriorated with the level of unbalance and/or distortions present in the grid voltages. To compensate for the abnormalities, such as unbalance and distortions in the grid voltages, positive sequence components (PSCs) of grid voltages are extracted from their filtered $ \alpha \beta$ components. This work implements hybrid generalized integrator (HGI) filters for filtering the $ \alpha \beta$ components of grid voltages and also provides its 90 $\circ$ delayed signals, which are useful in generating PSCs. Phase and frequency of the grid currents are decided by the unit active templates derived from the PSCs of the grid voltages, therefore, high-quality grid currents are injected into the grid even for abnormal grid conditions. For faster dynamics during variations in load power, HGI filters are used for quick and accurate estimation of fundamental components of load currents. Intermittent power generation from WEGS is compensated for by integrating a battery bank into the system. Along with high-quality power injection, the grid side converter operates the microgrid in off-grid mode (during grid outages) and provides smooth grid integration once the grid reappears. A 3.7 kW speed sensorless synchronous reluctance generator is used in WEGS, which is controlled by the machine side converter. The control techniques are validated in MATLAB /Simulink platform, and experimental validation is done on a prototype developed in the laboratory.

Sensorless Synchronous Reluctance Motor Drives: A Projection Vector Approach for Stator Resistance Immunity and Parameter Adaptation

This article presents a general projection vector framework for the analysis of flux and position observers applied to sensorless control of synchronous reluctance (SyR) machines, with emphasis to parametric errors sensitivity. The stator resistance immunity property of Adaptive Projection vector for Position error estimation (APP) technique is demonstrated in maximum torque per ampere (MTPA) conditions. Out of MTPA, additional resistance adaption is devised for accurate estimation of stator flux and torque. Alternatively, inductance adaptation might be preferred to resistance's, when dealing with inaccurate motor flux-maps. Inductance adaptation is shown to decrease the steady-state position error. All the proposed APP observers with adaptation techniques are subjected to stability analysis. The merit and the feasibility of the proposed scheme are experimentally demonstrated on a 1.1-kW SyR machine test bench.

Simulation and Implementation of Predictive Speed Controller and Position Observer for Sensorless Synchronous Reluctance Motors

A position observer and a predictive controller for sensorless synchronous-reluctance-motor (SynRM) drive systems are investigated in this paper. The rotor position observer, based on motor parameters, and stator currents and voltages, was designed and implemented to compute the rotor position. A pole-assignment technique was used to provide similar converging rates of the position observer, even when operated at different speeds. Furthermore, a predictive controller was designed to enhance performance. A digital-signal processor (DSP), TMS-320F-28335, was used as a computation tool. Several simulated results are provided and compared with the measured results. The measured results showed that the implemented predictive controller sensorless SynRM drive system could be adjusted from 30 to 1800 rpm with satisfactory performance, including quicker and better tracking responses, and a lower speed drop than that of a proportional-integral (PI) controller.

Position Sensor-Less Synchronous Reluctance Generator Based Grid-Tied Wind Energy Conversion System With Adaptive Observer Control

A new wind energy conversion system (WECS), with a position sensor-less synchronous reluctance generator (SynRG), integrated to the grid is proposed in this paper. Simple, brushless, compact structure of SynRG along with a full-scale converter makes it suitable for wind power applications. SynRG offers a fast dynamic response due to the absence of permanent magnets and windings in the rotor thus eliminating rotor losses completely. The torque pulsation from wind turbine (WT) are prevented from being transmitted to the grid by making use of a back-to-back (BTB) connected full-scale converters. The WECS and the grid are sharing a common DC-link through their respective voltage source converters (VSCs). The VSC connected to the machine side provides the required reactive power to the SynRG and operates it at a speed decided by the maximum power point (MPP) algorithm. A rotor position/speed sensor-less field-oriented control is implemented for controlling the SynRG. A fast, accurate, and oscillation-less adaptive observer based algorithm is introduced for the grid integration of WECS. MATLAB®/Simulink platform is used for the modeling and simulation of the system and a laboratory prototype is used for its experimental validation.

Predictive controller design for a high‐frequency injection sensorless synchronous reluctance drive system

This study proposes implementation of a predictive controller for a sensorless synchronous reluctance drive system. First, high-frequency voltage is injected in the α -axis. Then by measuring the α - β axis high-frequency currents, the rotor position of the SynRM can be estimated. After that, a predictive speed controller is implemented to improve transient responses, load disturbance responses, and tracking responses. To demonstrate its viability, a proposed 560 W sensorless drive system is implemented by using a TMS-320F-28335 DSP made by Texas Instruments and some circuits. Experimental results clearly indicate that the proposed high-frequency α -axis voltage injection method with a predictive speed-loop controller offers superior responses including faster transient responses, better load disturbance responses, and better tracking responses than a high-frequency d - q axis voltage injection method with a PI speed-loop controller.

Adaptive controller with an improved high‐frequency injection technique for sensorless synchronous reluctance drive systems

This paper proposes an adaptive controller with an improved high-frequency injection method for sensorless synchronous reluctance drive systems. A mathematical model is presented to show that the use of a high-frequency injection method that takes into account the effects of unequal mutual-inductances and the influence of speed reduces the rotor position estimation error. The adaptive speed control algorithm offers improved transient performance in comparison to typical proportional–integral (PI) controllers that are employed in sensorless drive systems. To demonstrate the viability, the proposed adaptive controller and the modified high-frequency injection method are implemented using a TMS-320F-28335A digital signal processor to control a 500 W prototype synchronous reluctance motor drive. Experimental results are presented to show that the transient, load disturbance, and tracking responses of the proposed drive system are superior in comparison to a drive that uses a PI controller. Both experimental and theoretical analyses clearly indicate that the proposed high-frequency injection method with an adaptive speed-loop controller offers improved performance in adjustable speed synchronous reluctance drive systems.

Design and implementation of a passivity-based controller for sensorless synchronous reluctance motor drive systems

This study proposes a passivity-based controller for sensorless synchronous reluctance motor drive systems. By using the proposed controller, the drive systems can achieve fast transient responses, good load disturbance responses and good tracking responses. The parameters of the controller can be derived according to the required specification of the drive systems. In addition, a new sensorless technique based on an extended flux estimator is proposed as well. The estimator provides good performance in transient and steady-state conditions. The details are discussed. A digital signal processor TMS-320F-28335 is used to execute the rotor position/speed estimation, the passivity-based control algorithm, the d–q to a–b–c coordinate transformation, and the pulse width modulation switching strategy. As a result, the hardware is very simple. Experimental results show that the proposed system can perform in a wide adjustable speed range from 1 to 2000 r/min and a precise position control with satisfactory performance.

Adaptive controller design for a synchronous reluctance motor drive system with direct torque control

The design and implementation of adaptive controllers for a sensorless synchronous reluctance drive system with direct torque control is proposed. Two adaptive control algorithms, which include adaptive backstepping control and model-reference adaptive control, are proposed to improve the performance of a sensorless direct torque control synchronous reluctance motor drive system. A digital signal processor, TMS320-C30, is used to execute the rotor position estimating technique and the adaptive control algorithms. The system shows good transient responses, good load disturbance responses and good tracking responses. Several experimental results validate the theoretical analysis. The advanced controller design for a sensorless synchronous reluctance motor drive with direct torque control is proposed.

Position Control of a Sensorless Synchronous Reluctance Motor

This paper presents a novel position control for a sensorless synchronous reluctance drive system. By measuring the three-phase currents of the motor, a rotor position estimator is achieved. Then, a velocity estimator is derived from the estimated rotor position by using a state estimating technique. The estimated velocity tracks the real velocity well. Next, a robust position controller is designed to improve the transient and load disturbance responses. By using the proposed estimating techniques and control algorithm, a high-performance sensorless synchronous reluctance drive is obtained. A digital signal processor, TMS-320-C30, is used to execute the estimating and control algorithms. No hardware circuit or external signal is added as compared with the traditional drive system with an encoder or resolver. To evaluate the performance of the position control system, a moving table is connected with the drive system. The drive system can precisely control the moving table. Experimental results show that the proposed system has good performance. Several experimental results validate the theoretical analysis.

Sensorless synchronous reluctance drive with standstill starting

This paper presents a novel sensorless synchronous reluctance drive system. Based on the dynamic model of the synchronous reluctance motor (SRM), a new rotor position estimator is proposed. This estimator is only related to the rate change of the stator currents. It is not related to the parameters, speed, voltage, and external load of the motor. As a result, the estimator is simple and robust. Based on the proposed estimator, a sensorless synchronous reluctance drive has been implemented. This drive system can start from standstill and accelerate to a rated speed; the traditional open-loop starting method, therefore, is unnecessary. A digital signal processor, TMS-320-C30, is used to implement the estimating and control algorithms. Experimental results show that the proposed system works well. The adjustable speed range can be from 1 r/min to 1800 r/min. Moreover, by adding the position-loop controller the proposed system can perform as a position control drive as well. Several experimental results validate the theoretical analysis.