Sensorless Control Algorithm Research Articles

Decoupling Algorithm for Online Identification of Inductance in Permanent Magnet Synchronous Motors Based on Virtual Axis Injection Method and Sensorless Control

Among the existing sensorless control algorithms for permanent magnet synchronous motors (PMSMs), the model reference adaptive system (MRAS) is widely utilized due to its merits of good robustness, high stability, and rapid response. Nevertheless, the performance of the sensorless control is largely determined by the identified inductance parameters. The virtual-rotary-axis high-frequency injection (VHFSI) method is an online identification strategy for PMSM inductance parameters which is not affected by the observed rotor position errors among inductance identification algorithms. However, the existing PMSM inductance online identification algorithm based on VHFSI has ignored the influence of the error components, resulting in low accuracy and the weak dynamic performance of the inductance identification algorithm. In response to the problems existing in the original method, this paper improves VHFSI by designing a feedforward decoupling algorithm to compensate for the error components. Theoretical verification and simulation results indicate that the improved identification algorithm enhances the accuracy of inductance parameter identification, significantly improves the dynamic tracking performance of inductance identification, and combines it with the MRAS sensorless control method to constitute a sensorless control system for the motor, thereby enhancing control performance and system stability.

Sensorless control algorithm for induction motor using adaptive observers

Sensorless control algorithm for induction motor using adaptive observers

Sensorless model-based displacement estimator for piezoelectric actuator through a practical three-stage mechanism

Piezoelectric elements (PEMs) are used in a variety of applications. In this paper, we developed a new simple sensorless method for a Piezoelectric Actuator (PEA), which includes piezostack elements and a three-stage amplification mechanism.This research focuses on a piezoelectric actuator that incorporates a three-stage amplification system, where the outcome of one stage serves as the input for the subsequent one. The actuator receives two types of inputs: the voltage applied to the piezoelectric elements and the mechanical load it carries. Its output is defined by the rotation angle observed at the end of the third amplification stage. To indirectly measure the actuator's displacement, a basic external circuit is utilized.The precise movement of these actuators is essential. To circumvent the high costs and limitations associated with highly accurate displacement sensors, there has been a growing interest in sensorless control methods. Certain electrical signals, when measured, can provide an estimation of displacement. However, induced voltage measurements are not effective for piezoelectric stacks. Two more promising measures are the voltage and current of the piezoelectric material.Given that the electrical charge on these actuators closely reflects their displacement with minimal hysteresis across a broad frequency spectrum, it's proposed that displacement can be effectively gauged through current measurements that assess charge.The core contribution of this paper is the introduction and validation, both theoretically and experimentally, of a hybrid algorithm that leverages these two electrical signals to enhance the accuracy of displacement estimates. This was confirmed using a laboratory setup.The primary benefit of this research is the presentation of a straightforward sensorless control algorithm, poised for further exploration within the realm of piezoelectric actuators. The simplicity of both the theoretical model and the sensorless technique facilitates their application across a diverse range of piezoelectric actuators and amplification systems, thereby streamlining the design, modeling, and control strategy development for various actuators.The innovation of this study stems from the application of an uncomplicated sensorless estimation algorithm, coupled with a system-level perspective on piezoelectric actuators. This approach utilizes a simple, adaptable model suitable for a wide array of applications and operational techniques.

Energy-saving starting method of electric motor based on the battery-accumulator hybrid drive

The series electro-hydraulic hybrid powertrain has advantages in improving the dynamic characteristics and increasing the cruising range of battery rail vehicles. In order to reduce the large peak starting current of electric motor, an energy-saving starting method is proposed, which is using the hydraulic pump/motor to reversely drive the electric motor to restart at a speed, based on the energy reverse transfer characteristics between electric motor and hydraulic pump/motor. Firstly, the principle of restarting the electric motor at a speed is proposed based on the designed EH3. Then, PID is adopted to control the starting of electric motor which is driven by hydraulic powertrain. And a speed sensorless control algorithm is designed to control the restarting at a speed. Finally, aiming at the problem that the traditional simulation models of electro-hydraulic hybrid powertrain components are too simple and ideal. The estimation model of battery and SOC, dynamic efficiency model of hydraulic motor and dynamic iron loss model of PMSM are improved and optimized to improve the accuracy of powertrain simulation. The results both of co-simulation and experiments shows that the starting current can be reduced by 69.36 % at most and 64.91 % of battery consumption can be saved by restarting the electric motor at a speed.

An Improved Full-Speed Domain Sensorless Control Scheme for Permanent Magnet Synchronous Motor Based on Hybrid Position Observer and Disturbance Rejection Optimization

A sensorless control algorithm not only reduces the cost of a permanent magnet synchronous motor (PMSM) system, but also broadens its application scope. Expanding speed threshold and enhancing dynamic performance are crucial aspects. To optimize the adaptability of observers and the immunity of the controller in a full-speed domain, an improved sensorless control scheme for a PMSM based on a hybrid position observer and disturbance compensation is proposed. Firstly, the precise detection of the initial position and the scheme of starting with the load at any position are proposed based on high-frequency rotation injection, magnetic pole direction calibration and square-wave high-frequency injection (HFI). Secondly, a higher-order sliding mode observer (HSMO) is designed to improve high-speed observation performance by introducing an extended electromotive force (EEMF). Correspondingly, a speed controller called PI plus is developed utilizing a reverse control algorithm and the observed disturbance quantity, which further enhances the system’s disturbance rejection capability. Subsequently, a linearly weighted observer switching method and a linear signal withdrawal scheme are proposed to suppress torque and speed oscillations in medium-speed threshold. Furthermore, a normalized linear extended state observer (LESO) is designed to enhance rotor information estimation accuracy and enable the observation of unknown disturbances in full-speed thresholds. Finally, the effectiveness of the proposed sensorless control system is tested through experiments involving variations in speed, load, and parameter. The experimental results indicate that the proposed sensorless strategy is capable of achieving a loaded start. The designed observer switching strategy and the scheme of injection signal withdrawal contribute to a smoother acceleration process. Furthermore, load variation test results at high-speed thresholds demonstrate that the proposed controller can reduce speed drop by 45 rpm compared to a traditional PI. Additionally, the results of parameter variation testing validate the observer’s robustness in the disturbances of ψf within the range of ±0.3 pu.

An Enhanced Distributed Control Architecture of Multiple Three-Phase PMSG for Improving Redundancy

Multiple three-phase permanent magnet synchronous generator (MTP-PMSG) has excellent fault-tolerant features in theory. However, the commonly used control architectures, such as the centralized control architecture with only one central controller and the distributed control architecture where the interconnected communication cables between controllers may fail, limit the fault tolerance of MTP-PMSG. Therefore, this paper proposes an enhanced distributed control (EDC) architecture without interconnected communication cables of MTP-PMSG for improving redundancy. The sensorless control and harmonic current suppression algorithm are considered and implemented in the EDC architecture. First, this paper analyzes the magnetic field coupling between the winding sets of MTP-PMSG, and the variation law of equivalent inductance of the winding sets under the condition of arbitrary current sharing is obtained. Then, an enhanced distributed sensorless control (EDSC) method in EDC architecture is proposed based on the equivalent inductance. Furthermore, this paper proposes a model-free predictive harmonic current (MFPHC) suppression method to solve the MTP-PMSG's inherent harmonic problem in the EDC architecture. The effectiveness of the proposed methods is verified by the comparative simulations and experiments in a dual three-phase PMSG (DTP-PMSG) with arbitrary current sharing of winding sets.

A Fixed-Point Position Observation Algorithm and System-on-Chip Design Suitable for Sensorless Control of High-Speed Permanent Magnet Synchronous Motor

In the sensorless control algorithm of permanent magnet synchronous motors (PMSMs), there is a significant research focus on developing a high-performance position observer and a cost-effective, high-performance processor specifically designed for PMSMs. In this paper, we first reviewed the current mainstream position observation algorithms. Subsequently, we proposed a position observation algorithm based on a fixed-point nonlinear flux linkage model that introduces a variable gain model and an observer compensation model. Furthermore, we implemented the improved position observation algorithm in the circuit and designed a System-on-Chip (SOC) suitable for the sensorless control of high-speed permanent magnet synchronous motors using the ARM Cortex-M0 core. The functionality of the proposed SOC was verified on the Field Programmable Gate Array (FPGA) platform. The results demonstrate that the improved algorithm offers an excellent angle observation accuracy and fast convergence speed. The error between the observed angle and the actual angle is less than 0.2 rad. Additionally, the designed SOC balances the high efficiency of hardware implementation with the flexibility of software implementation. When running a sensorless control algorithm for PMSM, it achieves a 30.3% increase in execution efficiency, enabling support for higher frequency output PWM switching and making it suitable for the high-precision control of high-speed PMSM.

A New Closed Loop Constant v/f Control of Induction Motor with Torque Control Based on DPWM

An easy sensor-less scalar control algorithm is described in this article as a method for controlling the speed of an induction motor. For developing a closed-loop v/f control of the induction motor drive, a torque controller with PI is implemented. The torque command was estimated by utilizing the voltage command, the feedback current, and a torque estimator. Additionally, a torque reference was provided for the Torque PI controller. Considering this, the purpose of this work is to investigate the closed-loop PI-based torque control of an induction motor drive that applies DPWM. In addition to this, it provides a description of a PI-based closed-loop torque control that works in conjunction with v/f control and tries to discover the most effective method for driving an induction motor based on an examination of Total Harmonic Distortion (THD) and torque ripple. To evaluate the performance studies of open- and closed-loop strategies with DPWM techniques for induction motor driving, the MATLAB/Simulink environment has been deployed. Experimental results have been validated.

A New Closed Loop Constant v/f Control of Induction Motor with Torque Control Based on DPWM

An easy sensor-less scalar control algorithm is described in this article as a method for controlling the speed of an induction motor. For developing a closed-loop v/f control of the induction motor drive, a torque controller with PI is implemented. The torque command was estimated by utilizing the voltage command, the feedback current, and a torque estimator. Additionally, a torque reference was provided for the Torque PI controller. Considering this, the purpose of this work is to investigate the closed-loop PI-based torque control of an induction motor drive that applies DPWM. In addition to this, it provides a description of a PI-based closed-loop torque control that works in conjunction with v/f control and tries to discover the most effective method for driving an induction motor based on an examination of Total Harmonic Distortion (THD) and torque ripple. To evaluate the performance studies of open- and closed-loop strategies with DPWM techniques for induction motor driving, the MATLAB/Simulink environment has been deployed. Experimental results have been validated.

Fault-Tolerant Self-Tuning Control for Three-Phase Three-Level T-Type Rectifier

This paper proposes a sensorless self-tuning control algorithm for a three-phase T-type rectifier. The proposed sensorless algorithm consists of three layers including an observer, which estimates grid voltages or currents based on the Kalman filter algorithm (KFA), an online estimator, which estimates the state-space matrix parameters, and a linear quadratic tracker (LQT), which is the main controller in this study. On the other hand, the performance of the LQT depends on the gains that need to be adjusted according to the system parameters, which is a challenge. To overcome this problem, a self-tuning method based on recursive least square algorithm (RLSA) is also proposed to tune the gains of LQT online. An experimental prototype is established, and the results, including the steady-state and dynamic performances, are carried out and presented to validate the effectiveness of the proposed controller.

Transient Response Characteristics Improvement of Permanent Magnet Synchronous Motor Based on Enhanced Linear Active Disturbance Rejection Sensorless Control

The compactness, cost decrease, and reliability of the auxiliary drive permanent magnet synchronous motors (PMSMs) for battery electric commercial vehicles can be further improved by adopting the position sensorless control technique. The conventional extended back electromotive force (EEMF) based sensorless control algorithm usually requires a phase-locked loop (PLL) and low pass filter to postprocess the estimated rotor position, which deteriorates the transient response of the PMSM significantly. To solve this problem, this article proposes an active disturbance rejection control based EEMF sensorless control method. By designing an extended state observer (ESO) considering the differential term of the position estimation error, timely and accurate estimation of the load disturbance and rotor position can be achieved simultaneously. The adaptive mechanism of the ESO exhibits sound system antidisturbance performance. Moreover, a linear state error feedback controller and feedforward compensation of load disturbance can replace the speed loop PI controller accordingly. Through stability and tracking performance analysis, the proposed method is superior in both steady-state performance and transient-state performance. The proposed scheme is experimentally validated by a 3 kW automotive power steering oil pump motor drive system. The results show that the transient response characteristics are obviously enhanced compared with the conventional methods. <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sup>

Steady-State Vibration Level Measurement of the Five-Phase Induction Machine during Third Harmonic Injection or Open-Phase Faults

Multiphase electric machines are increasingly used in various industries and for electromobility. Complex systems have been developed for the control and powering of multiphase machines, which require verification. The quality of control and the power supply of electric machines is usually evaluated by analyzing various electrical parameters. On the other hand, taking into account the fact that a motor is an electrical-mechanical object, its full diagnostics should also include the analysis of vibration signals to verify the operation of the motor as a mechanical device. In this paper, a sensorless control algorithm was studied and applied to a 5-phase induction motor. Various scenarios were considered; in particular, the operation of the studied motor in the absence of one or two phases and in the case of the introduction of the third harmonic to increase the torque was analyzed. In the scenarios considered, the motor was connected to another machine and operated with no load as well as with a preset load. The results obtained were analyzed in the time and frequency domain and were related to the standards used.

Sensorless Control of High-Speed Motors Subject to Iron Loss

It is widely recognized that the iron loss produced by motors at high speeds will directly affect the angle and size of the back electromotive force, and, therefore, it cannot be ignored. In this paper, a high-performance sensorless control algorithm is proposed for high-speed permanent magnet synchronous motors (HSPMSM), taking the iron loss into account. First, the resistance representing the core loss is precalculated by finite element analysis, and then a sliding mode observer with disturbance observation is designed to estimate the rotor position. The observer possesses the advantages of suppressing the chattering phenomenon and enhancing the robustness against uncertainty. Meanwhile, the idea of the characteristic model is used to design an adaptive robust control law to improve the speed control accuracy. Subsequently, a sensorless control scheme is proposed by using the proposed observer in combination with the designed control scheme. The stability of the observer and controller is verified by the Lyapunov theory method. Finally, a simulation example is given to demonstrate the correctness and the effectiveness of the proposed algorithm.

A novel rotor position fault diagnosis strategy

This paper presents a novel rotor position fault diagnosis strategy for synchronous motor (SM) for identifying rotor position faults of SM. The safe and reasonable operation areas of rotor position and angular speed fluctuation are predicted through the rotor position model prediction method considering the noise and load change. The rotor position fault diagnosis is realized by judging whether the real-time position and angular speed fluctuation data are in a safe and reasonable operation area, and faults can be identified within one PWM cycle. The algorithm is robust to noise on fault diagnosis and considers the effect of load characteristics. Furthermore, it decouples from other sensorless control algorithms. Also, the algorithm can be applied to switch from position-based to position sensorless control of the SM. And fault-tolerant control is further implemented to ensure the safe and reliable operation of the motor control system. Theoretical analysis and simulation results demonstrate the effectiveness of the proposed control strategy.

Hybrid Pulse High-Frequency Voltage Injection Control Algorithm of Sensorless IPMSM for Vehicles

A hybrid pulse vibration high-frequency voltage signal injection method is proposed to solve the problems that the conventional sensorless control algorithm of vehicle IPMSM may generate a large estimated rotor position error and opposite directions in identifying the polarity of magnetic poles under zero-speed and high-torque starting and low-speed operation. The magnetic pole polarity is identified by the saturation effect of the flux chain by injecting a high-frequency sinusoidal voltage signal and opposite pulse voltage signal into the axis of the assumed coordinate system simultaneously. Subsequently, the position relationship between the assumed axis and the actual d axis is studied in accordance with the amplitude of response current to acquire the rotor position and speed information. The simulation and experimental results suggest that the algorithm is capable of accurately identifying the magnetic pole polarity and estimating the rotor position at zero speed and low speeds, starting the motor smoothly at zero speed, and then operating the motor stably at low speeds.

HF-Based Sensorless Control of a FTPMM in Ship Shaftless Rim-Driven Thruster System

Take a dual-winding permanent magnet fault tolerant motor (FTPMM) in the ship shaftless rim-driven thruster (RDT) as the research object, the position sensorless control algorithm based on high frequency (HF) current injection is presented to estimate the rotor position and the rotor position signal is extracted from the voltage. In order to reduce influences of proportional-integral (PI) controller, current regulators and voltage calculation errors, the generalized second-order integrator (SOGI) is discussed along with how to combine with the low-speed sensorless control. And the current vector fault-tolerant control strategy is applied to compensate for the faulty phase current with other healthy phase currents. The rotor position at low speed is estimated under healthy as well as open-circuit faulty conditions by using the HF current injection algorithm based on SOGI (HF-SOGI). After simulation in Matlab/Simulink, the experimental results further demonstrate the feasibility of the HF-SOGI strategy by the FTPMM experimental setup. It can be calculated that the rotor speed ripple is decreased obviously after fault-tolerant control strategy is applied. It can be concluded that the HF-SOGI strategy can estimate the position accurately, which can further improve the reliability and application scope of FTPMM and the RDT system.

Output Power Control and Load Mitigation of a Horizontal Axis Wind Turbine with a Fully Coupled Aeroelastic Model: Novel Sliding Mode Perspective

The power control of horizontal axis wind turbines can affect significantly the vibration loads and fatigue life of the tower and the blades. In this paper, we both consider the power control and vibration load mitigation of the tower fore-aft vibration. For this purpose, at first, we developed a fully coupled model of the NREL 5MW turbine. This model considers the full aeroelastic behaviour of the blades and tower and is validated by experiment results, comparing the time history data with the FAST (Fatigue, Aerodynamics, Structures, and Turbulence) code which is developed by NREL (National Renewable Energy Lab in the United States). In the next, novel sensorless control algorithms are developed based on the supper twisting sliding mode control theory and sliding mode observer for disturbance rejection. In region II (the wind speed is between the cut-in and rated wind velocity), the novel sensorless control algorithm increased the power coefficient in comparison to the conventional indirect speed control (ISC) method (the conventional method in the industry). In region III (the wind speed is between the rated and cut-out speed), an adaptive neural fuzzy inference system (ANFIS) is developed to estimate pitch sensitivity. The rotor speed, pitch angle, and effective wind velocity are inputs, and pitch sensitivity is the output. The designed novel pitch control performance is compared with the gain scheduled PI (GPI) method (the conventional approach in this region). The simulation results demonstrate that the flapwise blade displacement is reduced significantly. Finally, to reduce the fore-aft vibration of the tower, a tuned mass damper (TMD) was designed by using the genetic algorithm and the fully coupled model. In comparison to the literature body, we demonstrate that the fully coupled model provides much better accuracy in comparison to the uncoupled model to estimate the vibration loads.

Disturbance Observer Based Sensorless Predictive Control for High Performance PMBLDCM Drive Considering Iron Loss

The control of motor drive without considering iron loss affects the phase back electromotive force and the torque performance. This article investigates the performance of permanent magnet brushless direct current motor (PMBLDCM) modeling taking impact of iron loss into account. A disturbance observer based sensorless scheme is proposed for PMBLDCM model with precise estimation of the rotor angular position. The effect of unmodeled nonlinear parameters on iron loss of PMBLDCM are regarded as disturbances for the proposed sensorless approach. A linear feedback control law with optimal current vector formulation is introduced to minimize the current ripple and torque ripple resulting in reduced copper loss. In order to select optimum switching vector considering the effect of iron loss, a model predictive control technique is proposed for the three-phase three-level neutral point clamped voltage source inverter driven PMBLDCM. The proposed sensorless predictive control (SPC) algorithm is verified both by simulation and experiments. The SPC approach demonstrates improved performance compared to the conventional approach in which the effect of iron loss is not taken into account.

Experimental Investigation of Sensorless Tension Control System for Textile Processes

Sensorless tension control system is investigated for textile processes and machines in this paper. A prototype unit unit was designed and manufactured for this aim. Prototype unit consisted of winding and unwinding warp beams driven by a servomotor and an induction motor. Warp tension was measured by load cells for evaluating the sensorless tension control system performance. Diameters of winding and unwinding warp beams were measured by laser sensors. Wound warp length was measured by an incremental encoder fitted to the shaft of a cylinder rotated by warp yarns. Number of beam rotations of warp beams were measured by separate inductive switches. A software program was developed in LabVIEW to implemet sensorless tension control algorithms and record the performance data. Results showed that the desired tension can be kept constant within 5% deviation limits by the servomotor torque control.

Methanol Sensor-Less Control Strategy for Direct Methanol Fuel Cell Startup

It is critical and challenging to start direct methanol fuel cells (DMFCs) from various environmental states to an ideal operating state by a sensor-less method. This paper presents a novel methanol sensor-less startup control (SLSC) algorithm based on the unimodal relationship of current vs. methanol concentration at a constant cell voltage during DMFC startup. A series of experiments indicate that the SLSC algorithm is capable of starting a DMFC under various initial concentrations and initial temperatures and can be easily adjusted to reduce the startup time or improve the energy efficiency. The wide applicability and easy adjustment characteristics give the SLSC algorithm a potential prospect in the DMFC system.