Entire Operating Speed Range Research Articles

Study on QEMF Model and Adaptive Full-Order Observer Design for Universal Sensorless Control of IPMSMs

Quadratic extended electromotive force (QEMF) model enabled the use of traditional high-speed adaptive estimation methods combined to high-frequency signal injection (HFSI) for full-range sensorless position control of interior permanent magnet synchronous motors (IPMSMs). However, the first QEMF model presented in literature only works with HFSI in the q-axis, due to the QEMF being a function of the q-axis current derivative. The q-axis HFSI is known to produce undesired torque ripple. Furthermore, q-axis signal injection can be insufficient for low-speed position estimation in IPMSMs with low salience. A recent study demonstrated that the QEMF concept can be modeled as a function of the d-axis current derivative. In this paper, the influence of d-axis HFSI on QEMF is investigated and compared to the q-axis HFSI method. Furthermore, the electromotive force based observers are usually designed for medium to high-speed operation. Here, the adaptive full-order observer is adapted in order to achieve universal sensorless control through QEMF based d-axis HFSI. The state observer and adaptive law are designed by a cascade methodology, which guarantees accurate EEMF estimation and robustness throughout the entire operating speed range. Experimental results are presented in order to validate the proposed method and analysis under full-range sensorless control.

Synchronous Homopolar Generator without Permanent Magnets for Railway Passenger Cars

The article presents the optimal design of a 35 kW brushless synchronous homopolar generator without permanent magnets for railway passenger cars. The excitation winding of the generator is located on the stator, and the toothed rotor has no windings. The generator characteristics are optimized considering the required constant power speed range. A single-objective Nelder–Mead algorithm and 2D Finite Element Analysis were used for the optimization. As a result of the optimization, power losses are significantly reduced over the entire operating range of the generator rotational speed, the current capacity of the solid-state rectifier, and the torque ripple. A comparison of the calculated characteristics of the generator under consideration with the characteristics of a commercially available undercar generator shows that the active volume is reduced by a factor of 2.1, and the losses are significantly reduced over the entire operating speed range.

Application of a Thermo-Hydrodynamic Model of a Viscous Torsional Vibration Damper to Determining Its Operating Temperature in a Steady State.

The problem of damping torsional vibrations of the crankshaft of a multi-cylinder engine is very important from the point of view of the durability and operational reliability of the drive unit. Over the years, attempts have been made to eliminate these vibrations and the phenomena accompanying them using various methods. One of the methods that effectively increases the durability and reliability of the drive unit is the use of a torsional vibration damper. The torsional vibration damper is designed and selected individually for a given drive system. A well-selected damper reduces the amplitude of the torsional vibrations of the shaft in the entire operating speed range of the engine. This paper proposes a thermo-hydrodynamic model of a viscous torsional vibration damper that enables the determination of the correct operating temperature range of the damper. The input parameters for the model, in particular the angular velocities of the damper elements as well as the geometric and mass dimensions of the damper were determined on a test stand equipped with a six-cylinder diesel engine equipped with a factory torsional vibration damper. The damper surface operating temperatures used in model verification were measured with a laser pyrometer. The presented comparative analysis of the results obtained numerically (theoretically) and the results obtained experimentally allow us to conclude that the proposed damper model gives an appropriate approximation to reality and can be used in the process of selecting a damper for the drive unit.

Investigations of Rubbing Phenomenon During Coast-Up Operation of a Cryogenic Engine Turbopump

Background A turbopump is an important and critical component in the liquid rocket engine assembly where a small deviation in the system parameters such as unbalance level, dimensional tolerances, rotor–stator clearance, etc. can have significant influence on its dynamic behavior and may lead to various faults such as rub. Hence, a detailed rotordynamic study is essential for the entire operating speed range.

Optimal Rotor Design of Claw-Pole Alternator for Performance Improving

Abstract: The subject of this paper is to optimize the design of conventional claw pole alternator for automotive industry, especially at idle speed. Commonly, during idle speed, claw pole alternator isn’t able to sustain active electrical loads for a reasonable amount of time without excessive drain on the battery. Therefore, obtaining sufficient output power at idle speed is required. The optimization process aims to improve alternator output power, at idle speed, for given stator dimensions and footprint. To derive the optimal rotor structure, cyclic coordinate method linked with magnetic equivalent circuit (MEC) model is used, including magnetic saturation effect and leakage flux. Optimization results, which provide the optimized rotor geometrical dimensions, are discussed. Performances regarding the optimized claw pole alternator are evaluated over the entire operating speed range of the vehicle.

Research on Automatic Balance Control of Active Magnetic Bearing‐Rigid Rotor System

In this paper, in order to solve the problem of unbalance vibration of rigid rotor system supported by the active magnetic bearing (AMB), automatic balancing method is applied to suppress the unbalance vibration of the rotor system. Firstly, considering the dynamic and static imbalance of the rotor, the detailed dynamic equations of the AMB‐rigid rotor system are established according to Newton’s second law. Then, in order to rotate the rotor around the inertia axis, the notch filter with phase compensation is used to eliminate the synchronous control current. Finally, the variable‐step fourth‐order Runge–Kutta iteration method is used to solve the unbalanced vibration response of the rotor system in MATLAB simulation. The effects of the rotational speed and phase compensation angle on the unbalanced vibration control are analysed in detail. It is found that the synchronous control currents would increase rapidly with the increase of rotational speed if the unbalance vibration cannot be controlled. When the notch filter with phase shift is used to balance the rotor system automatically, the control current is reduced significantly. It avoids the saturation of the power amplifier and reduces the vibration response of the rotor system. The rotor system can be stabilized over the entire operating speed range by adjusting the compensation phase of the notch filter. The method in the paper is easy to implement, and the research result can provide theoretical support for the unbalance vibration control of AMB‐rotor systems.

Stabilizing an Urban Semi-Autonomous Bicycle

A comprehensive and a deep analysis on how to stabilize an urban semi-autonomous bicycle was carried out. Its more relevant aspects are presented in this paper. The resulting stabilized bicycle is intended to serve as a future evolution for the current bike-share programs. This bicycle would go to meet the user autonomously, and after that it could be used by the rider in the traditional fashion. Therefore, the resulting system must be stable throughout the entire operating speed range and must be rideable by a person when used in manual mode. A study of bicycle dynamics and stability control has led the way followed throughout this investigation. Consecutively, all the examined aspects are applied to introduce a few alternatives for solving the stability problem. One of them, the Alnilam concept, is further developed to unveil its possibilities. Furthermore, it has been successfully tested in a multibody co-simulation using Adams and Simulink, thus illustrating its behavior and testing its performance. The results of this simulation are very promising and encouraging to further develop this concept.

Power and fuel economy optimizations of gasoline engines using hydraulic variable valve actuation system

The hydraulic variable valve actuation (HVVA) system can provide greater freedoms to the engine valve motions than most of the traditional cam-based valve train systems do. By considering the characteristics of the HVVA system, the strategies of putting its outstanding flexibilities into use for further improving the performances of gasoline engines with respect to power and fuel economy are developed in this research. A new GT-suite HVVA engine model is proposed which is able to realize the interdependencies of the HVVA system and the engine. In addition, the model is calibrated by experimental data and the proposed genetic algorithm (GA) optimization schemes are carried out for optimizing the engine outputs at full engine load and fuel economy at partial engine load. A potential average improvement of 10.4% on the engine outputs at full load over the entire operating speed range of the test engine is noticed from implementing the optimized HVVA valve motions. Moreover, the advanced GA algorithm for fuel economy optimization ensures the GA optimizer could maintain its proper functionality while non-linear constraints are taken into considerations. The late exhaust valve closure (LEVC) and early intake valve closure (EIVC) strategies are adopted at the same time for granting the engine an internal exhaust gas recirculation (IEGR) feature and together evolved into the HVVA strategy for fulfilling the partial engine loads without throttling. By conducting the advanced GA optimizations with the proposed HVVA strategy for partial engine load operations, the resulted break specific fuel consumption (BSFC) of the HVVA engine could be brought down by 13.1% on average with a maximum of 15.8% over its working speed range at the exemplary 7Nm load point comparing to those of the original test engine.

Self-Correction of Commutation Point for High-Speed Sensorless BLDC Motor With Low Inductance and Nonideal Back EMF

This paper presents a novel self-correction method of commutation point for high-speed sensorless brushless dc motors with low inductance and nonideal back electromotive force (EMF) in order to achieve low steady-state loss of magnetically suspended control moment gyro. The commutation point before correction is obtained by detecting the phase of EMF zero-crossing point and then delaying 30 electrical degrees. Since the speed variation is small between adjacent commutation points, the difference of the nonenergized phase's terminal voltage between the beginning and the end of commutation is mainly related to the commutation error. A novel control method based on model-free adaptive control is proposed, and the delay degree is corrected by the controller in real time. Both the simulation and experimental results show that the proposed correction method can achieve ideal commutation effect within the entire operating speed range.

Implementation of a MFAC based position sensorless drive for high speed BLDC motors with nonideal back EMF

In order to improve the reliability and reduce power consumption of the high speed BLDC motor system, this paper presents a model free adaptive control (MFAC) based position sensorless drive with only a dc-link current sensor. The initial commutation points are obtained by detecting the phase of EMF zero-crossing point and then delaying 30 electrical degrees. According to the commutation error caused by the low pass filter (LPF) and other factors, the relationship between commutation error angle and dc-link current is analyzed, a corresponding MFAC based control method is proposed, and the commutation error can be corrected by the controller in real time. Both the simulation and experimental results show that the proposed correction method can achieve ideal commutation effect within the entire operating speed range.

Four-Quadrant Torque Ripple Minimization of Switched Reluctance Machine Through Current Profiling With Mitigation of Rotor Eccentricity Problem and Sensor Errors

This paper presents a method of profiling the phase currents to minimize the torque ripple of switched reluctance machines (SRMs) operating in four-quadrant mode over the entire speed range of operation. The method is based on machine and controller design through coupled simulation of the finite-element-based machine model and the dynamic controller model. The method considers the mutual coupling effect between conducting phases. The research quantifies the effect of sensor error and manufacturing build variations on the level of torque ripple minimization. The mitigation processes to address the issues in mass production are also presented.

Suppression of imbalance vibration for AMBs controlled driveline system using double-loop structure

Because of the couplings without off-line balancing and the uneven distribution of the rope, the equivalent residual unbalances in the active magnetic bearing (AMB) controlled driveline system are considerable. Therefore it is necessary to achieve suppressing the synchronous vibration force over the entire operating speed range. To completely achieve automatic balance of the rotor, a double-loop compensation design approach based on the AMB is proposed. Firstly, a dynamic model of the rotor with imbalance and the decentralized control system of magnetic bearing are established. Then the imbalance characteristic of the rotor system is identified by the generalized notch in which sign of the convergence coefficient needs to be changed according to the rotational speed. Finally, the second loop which is a simply feedforward loop at low speeds and switched to an adaptively tuning loop at high speeds is used to adjust the control current to achieve complete suppression of the imbalance vibration force. The method can achieve automatic balancing within the entire operating speed range and the effectiveness is unaffected by the attenuation of power amplifier at high speeds. Simulation and experiment results well demonstrate effectiveness of the approach, and the stability of the whole system is guaranteed.

A Fixed Switching Frequency Predictive Current Control Method for Switched Reluctance Machines

The paper presents a novel fixed switching frequency predictive current control method for switched reluctancemachines (SRM). The proposed deadbeat predictive current controller accurately predicts the required duty ratio for thePWM pulse for a given reference current in each digital time step over the entire speed range of operation. The pulsewidth depends on the operating conditions, machine parameters and the rotor position. The controller utilizes themachine inductance profile as a function of current and rotor position to accurately predict the required voltage. Thecontrol method is studied through computer simulation and followed by experimental validation. The method is suitablefor torque ripple sensitive applications requiring accurate tracking of a given current profile and mitigating theaudible noise due to the switching of the inverter.

Improving Switching Frequency Variation of Hysteresis Current Controlled VSI Fed Induction Motor Drive

Switching frequency variation over the entire operating speed range of an induction motor (IM) drive is the major problem associated with conventional two-level threephase hysteresis controller as well as the space phasor based pulse width modulation (PWM) hysteresis controller. This paper presents a new variable band hysteresis current controller for controlling the switching frequency variation in the two-level PWM inverter fed IM drives for various operating speeds. A novel concept of online variation of the band based on both the instantaneous load current and current change for eachsampling period is presented to determine the hysteresis band. A performance comparison of the proposed with conventional hysteresis current controller for IMdrive is provided in simulation. The proposed drive system is also implemented in real-time using DSP board DS1104 for a laboratory 1.5 hp motor. Comparative simulation andreal-time results verify the feasibility of the proposed scheme and demonstrate that the proposed method has obtained constant switching frequency and improved the performance of the drive system.

Dynamic stability of an aerodynamically efficient motorcycle

Motorcycles exhibit two potentially dangerous oscillatory modes known as ‘wobble’ and ‘weave’. The former is reminiscent of supermarket castor shimmy, while the latter is a low frequency ‘fish-tailing’ motion that involves a combination of rolling, yawing, steering and side-slipping motions. These unwanted dynamic features, which can occur when two-wheeled vehicles are operated at speed, have been studied extensively. The aim of this paper is to use mathematical analysis to identify important stability trends in the on-going design of a novel aerodynamically efficient motorcycle known as the ECOSSE Spirit ES1. A mathematical model of the ES1 is developed using a multi-body dynamics software package called VehicleSim [Anon, VehicleSim Lisp Reference Manual Version 1.0, Mechanical Simulation Corporation, 2008. Available at http://www.carsim.com]. This high-fidelity motorcycle model includes realistic tyre–road contact geometry, a comprehensive tyre model, tyre relaxation and a flexible frame. A parameter set representative of a modern high-performance machine and rider is used. Local stability is investigated via the eigenvalues of the linearised models that are associated with equilibrium points of interest. A comprehensive study of the effects of frame flexibilities, acceleration, aerodynamics and tyre variations is presented, and an optimal passive steering compensator is derived. It is shown that the traditional steering damper cannot be used to stabilise the ES1 over its entire operating speed range. A simple passive compensator, involving an inerter is proposed. Flexibility can be introduced deliberately into various chassis components to change the stability characteristics of the vehicle; the implications of this idea are studied.

Rotor Model Validation for an Active Magnetic Bearing Machining Spindle Using Mu-Synthesis Approach

Model-based identification and μ-synthesis are employed for model updating of the rotor for a high-speed machining spindle supported on active magnetic bearings. The experimentally validated model is compared with a nominal engineering model to identify the unmodeled dynamics. The extracted missing dynamics from the nominal rotor model provides engineering insight into an effective model correction strategy. The corrected rotor model is validated by successful implementation of a number of μ-synthesized controllers, providing robust and stable levitation of the spindle over its entire operating speed range.

Vibration Control of a Nonlinear Rotor System through Electro-Magnetic Bearings

In rotating machinery, vibration resonance with large amplitude and complex pattern occurs at critical speeds due to rotor imbalance and nonlinear effects. In this paper, a vibration control method is proposed for a rotor system supported by a ball bearing and an electro-magnetic bearing. In particular, a disturbance observer combined with the current delay estimation is implemented to improve the controller's ability of compensating for system's nonlinear effects and uncertainty. As a result, the rotor vibration is suppressed to very small amplitudes in the entire operating speed range. The proposed method is validated through numerical simulations and experiments.

Vibration Control of a Nonlinear Rotor System through Electro-Magnetic Bearings

In rotating machinery, vibration resonance with large amplitude and complex pattern occurs at critical speeds due to rotor imbalance and nonlinear effects. In this paper, a vibration control method is proposed for a rotor system supported by a ball bearing and an electro-magnetic bearing. In particular, a disturbance observer combined with the current delay estimation is implemented to improve the controller's ability of compensating for system's nonlinear effects and uncertainty. As a result, the rotor vibration is suppressed to very small amplitudes in the entire operating speed range. The proposed method is validated through numerical simulations and experiments.

A Rotor Flux Estimation During Zero and Active Vector Periods Using Current Error Space Vector From a Hysteresis Controller for a Sensorless Vector Control of IM Drive

This paper proposes a sensorless vector control scheme for general-purpose induction motor drives using the current error space phasor-based hysteresis controller. In this paper, a new technique for sensorless operation is developed to estimate rotor voltage and hence rotor flux position using the stator current error during zero-voltage space vectors. It gives a comparable performance with the vector control drive using sensors especially at a very low speed of operation (less than 1 Hz). Since no voltage sensing is made, the dead-time effect and loss of accuracy in voltage sensing at low speed are avoided here, with the inherent advantages of the current error space phasor-based hysteresis controller. However, appropriate device on-state drops are compensated to achieve a steady-state operation up to less than 1 Hz. Moreover, using a parabolic boundary for current error, the switching frequency of the inverter can be maintained constant for the entire operating speed range. Simple σLs estimation is proposed, and the parameter sensitivity of the control scheme to changes in stator resistance, Rs is also investigated in this paper. Extensive experimental results are shown at speeds less than 1 Hz to verify the proposed concept. The same control scheme is further extended from less than 1 Hz to rated 50 Hz six-step operation of the inverter. Here, the magnetic saturation is ignored in the control scheme.

Nonlinear Model Predictive Control of a Simplified Wind Turbine

AbstractThis paper discusses the implications of formulating a single control law governing the entire wind speed range of operation for a wind turbine. Furthermore, the knowledge of future wind speeds provided by e.g. LIDARs is included in the controller framework. This is possible as the presented controller is based on nonlinear model predictive control and includes the knowledge of the future wind speed in the prediction horizon of the controller. The potential benefits of exploiting the knowledge provided by LIDARs is demonstrated in simulations with a simplified 1 degree-of-freedom nonlinear wind turbine model.