Operating Speed Range Research Articles

Analysis and Classification of Faults in Switched Reluctance Motors Using Deep Learning Neural Networks

The simple and robust construction, less weight, wide operating speed range, and higher fault tolerance capability of switched reluctance (SR) motor make it a viable contender for the conventional dc and ac machines. The faults at the rotor, winding, stator converters, and sensors lead to overcurrent, increase torque ripples, and sudden breakdown of the system. Thus, it is an urgent requirement to recognize and classify the faults that exist in switched reluctance motors, thereby the reliability, robustness, and widespread utilization of SR motors can be increased. The phases of the SR Motor are excited by using an asymmetric bridgeless resonance converter. This paper proposes an automatic diagnosis and classification of faults using radial basis function neural network (RBFNN). A mathematical model of the SR motor is established to determine the state of the art of fault condition of SR motors. The speed data of SR motor are utilized by RBFNN to generate fault information. Gabor filter is used for preprocessing the input data, and segmentation is achieved using high accurate DCT-DOST transformation. A gray-level co-occurrence matrix optimized with a genetic algorithm is used to extract the features in the speed signal of the motor. A test setup was developed in MATLAB to measure the performances of the RBFNN classifier in real-time. The effectiveness of the simulated fault classification model is verified by comparing the results of the conventional PI controller with several optimized algorithm-based tuned PI controllers.

Application of Reference Voltage Control Method of the Generator Using a Neural Network in Variable Speed Synchronous Generation System of DC Distribution for Ships

In the case of DC power distribution-based variable speed engine synchronous generators, if the output reference voltage is kept constant regardless of the generator engine operating speed, it may cause damage to the internal device and windings of the generator due to over-flux or over-excitation. The purpose of this study is to adjust the generator reference voltage according to the engine speed change in the DC distribution system with the variable speed engine synchronous generator. A method of controlling the generator reference voltage according to the speed was applied by adjusting the value of the variable resistance input to the external terminal of the automatic voltage regulator using a neural network controller. The learning data of the neural network was measured through an experiment, and the input pattern was set as the rotational speed of the generator engine, and the output pattern was set as the input current of the potentiometer. Using the measured input/output pattern of the neural network, the error backpropagation learning algorithm was applied to derive the optimum connection weight to be applied to the controller. For the test, the variable speed operation range of the generator engine was set to 1100–1800 rpm, and the input current value of the potentiometer according to the speed increase or decrease within the operation range and the output of the voltage output from the actual generator were checked. As a result of neural network control, it was possible to confirm the result that the input current value of the potentiometer accurately reached the target value 4–20 mA at the point where the initial speed change occurred. It was confirmed that the reference voltage was also normally output in the target range of 250–440 V.

Expansion of Operating Speed Range of High-Speed BLDC Motor Using Hybrid PWM Switching Method Considering Dead Time

In vehicle electrical systems with limited battery power, the output torque and speed of high-speed brushless DC (BLDC) motors can decrease due to unstable and reduced supply voltage or manufacturing errors in the motor back electromotive force (EMF). This paper presents a method that can guarantee the output performance of an inverter through a control algorithm without a separate power supply system and DC-link voltage increase. The proposed control algorithm can increase the output torque and speed of a high-speed BLDC motor by using appropriate selection and change of the inverter’s pulse width modulation (PWM) control method. In this paper, the operation and electrical characteristics of various PWM methods of BLDC motors are analyzed, and the optimal PWM method for improving the control performance of high-speed BLDC motors is presented. In addition, the relationship between the switching frequency, dead time, and voltage utilization was mathematically analyzed. Based on the results of this analysis, the proposed control algorithm automatically changes the PWM switching mode at the point where the output torque and speed need to be extended. The effectiveness and feasibility of the control method proposed in this paper is verified through the experimental results on the designed and manufactured high-speed BLDC motor system for vehicles.

Research on Absolute Positioning Sensor Based on Eddy Current Reflection for High-Speed Maglev Train.

A novel absolute positioning sensor for high-speed maglev train based on eddy current effect is studied in this paper. The sensor is designed with photoelectric switch and four groups of unilateral coplanar code-reading detection coil combination. The photoelectric switch realizes the positioning of the marker plate, and the four groups of detection coils read the mileage code of the mileage sign plate to obtain the absolute mileage information of the vehicle, which effectively reduces the quality and volume of the sensor, and reduces the impact of ice and snow. At the same time, the code-reading reliability and speed adaptability index are proposed. The code-reading reliability of the sensor is analyzed and tested under the fluctuation of levitation guidance, and the positioning error under the speed range of 0–600 km/h is calculated and analyzed. The results show that the novel sensor has the advantages of simple and compact structure. It still satisfies the system’s requirements for absolute vehicle mileage information under the conditions of vehicle operating attitude fluctuations and changes in the full operating speed range.

General principles of expanding the speed range of operation of autonomous power supply systems for passenger cars

Authors address the issues of expanding the speed range for operation of autonomous power supply systems for air-conditioned passenger cars. For the first time in the domestic car construction, the issue of reducing the minimum start-up speed of a generator-drive unit arose when the passenger fleet of the Sakhalin Railway was renewed, where the speed of passenger cars is much lower than the overall network speed. Research carried out by CJSC SO TIV and JSC TVZ has shown that the use of V-belts in the modernization of the textropic-reduction-cardan drive allows solving this problem. Kinematic diagram of the drive was adopted without changes, but with the replacement of the V-belts C (B)-2360T with new narrow belts XPC-2360 without working surface wrap and with a formed tooth on the lower base. In the tensioner, the main spring with a stiffness of 75 N/mm was replaced with a spring of increased stiffness (100 N/mm). The main change was the replacement of the 2GV003 generator with a 2GV008 low-speed generator, which has a minimum rotation at full power (700 rpm). This modernization of the drive made it possible to turn on the generator 2GV008 at rated power, starting at a speed of 30 km/h. The article sets the task of expanding the speed range of operation of the EV-7 and EV-10 autonomous power supply systems for cars without air conditioning. It is solved by forcing the excitation of the generators. Analysis of modern systems of autonomous power supply of passenger cars showed that the expansion of the speed range of its operation can be achieved in three ways: • raising the gear ratio of the gearbox to ensure it is switched on to the nominal mode at a carriage speed of 15 - 20 km/h without changing the parameters of the generator and the entire system of autonomous power supply; • modernization of the electrical equipment complex for passenger cars to ensure the operation of the main power consumers and charge the battery while driving at low speeds (over 18 km/h) without changing the mechanical parameters and composition of the serial generator-drive unit; • modernization of the generator in order to reduce its turnon revolutions to the power required to provide the main power consumers without changing the mechanical parameters of the drive. All three methods have its advantages and disadvantages, the choice of any of them is determined by the technical requirements for a specific car model.

Conceptual Approach on Feasible Hydrogen Contents for Retrofit of CNG to HCNG under Heavy-Duty Spark Ignition Engine at Low-to-Middle Speed Ranges

Hydrogen-based engines are progressively becoming more important with the increasing utilization of hydrogen and layouts (e.g., onboard reforming systems) in internal combustion engines. To investigate the possibility of HICE (hydrogen fueled internal combustion engine), such as an engine with an onboard reforming system, which is introduced as recent technologies, various operating areas and parameters should be considered to obtain feasible hydrogen contents itself. In this study, a virtual hydrogen-added compressed natural gas (HCNG) model is built from a modified 11-L CNG (Compressed Natural Gas) engine, and a response surface model is derived through a parametric study via the Latin hypercube sampling method. Based on the results, performance and emission trends relative to hydrogen in the HCNG engine system are suggested. The operating conditions are 1000, 1300, and 1500 rpm under full load. For the Latin hypercube sampling method, the dominant variables include spark timing, excess air ratio (i.e., λCH4+H2), and H2 addition. Under target operating conditions of 1000, 1300, and 1500 rpm, the addition of 6–10% hydrogen enables the virtual HCNG engine to reach similar levels of torque and BSFC (brake specific fuel consumption) compared to same lambda condition of λCH4. For the relatively low 1000 rpm speed under conditions similar to those of the base engine, NOx formation is greater than base engine condition, while a similar NOx level can be maintained under the middle speed range (1300 and 1500 rpm) despite hydrogen addition. Upon addition of 6–10% hydrogen under the middle speed operation range, the target engine achieves performance and emission similar to those of the base engine.

Deadbeat-Based Model Predictive Voltage Control for a Sensorless Five-Phase Induction Motor Drive

This paper introduces a direct model predictive voltage control (DMP VC) for a sensorless five-phase induction motor drive. The operation of the proposed sensorless DMP VC is based on the direct control of the applied stator voltages instead of controlling the torque and flux as in model predictive direct torque control (MP DTC). Thus, the simplicity of the control system is enhanced, which saves the computational time and reduces the commutation losses as well. The methodology based on which the proposed sensorless DMP VC performs its operation depends on minimizing a cost function that calculates the error between the reference and actual values of the direct and quadrature (d-q) axes components of stator voltages. The reference values of d-q components of stator voltages are obtained through incorporating the deadbeat control within the proposed model predictive system. A robust back-stepping observer is proposed for estimating the speed, stator currents, rotor flux, and rotor resistance. The validity of the proposed sensorless DMP VC is confirmed through performing detailed and extensive comparisons between the proposed DMP VC and MP DTC approach. The obtained results state that the drive is exhibiting better performance under the proposed DMP VC with less ripples content and reduced computational burden. Moreover, the proposed back-stepping observer has confirmed its effectiveness in estimating the speed and other variables for a wide range of speed operation.

Investigation on the rotordynamic performance of hybrid bump-metal mesh foil bearings rotor system

The rotordynamic performance of a new designed gas foil bearing, hybrid bump-metal mesh foil bearing (HB-MFB), was investigated in this study. The elastic substructure of the HB-MFB was comprised by the foil strips and metal mesh blocks, which is different from the traditional bump-type gas foil bearing. The metal mesh material was introduced to improve the damping of the bearing, thus improving the stability of the rotor system. The new designed HB-MFB was manufactured and tested on a rotordynamic test rig in this study. The rotor responses were measured and analyzed under different operating conditions and bearing parameters. A theoretical model of the HB-MFB rotor system was built and demonstrated by the experiment results. The performance of HB-MFB was compared with traditional bump-type gas foil bearings. The effect of bearing parameters and operating conditions, like imbalance, mesh density, bearing load, and bearing clearance, on the rotordynamic performance of HB-MFB rotor system was studied experimentally and analyzed theoretically. The experiment results demonstrated that introducing metal mesh can suppress the subsynchronous vibration significantly, which means the stability can be improved. The critical speed changes slightly, while the synchronous amplitude increases as the imbalance increases in the whole operating speed range. The rotor responses under different static loads showed the stability was improved as the static load increases because of the improvement of the natural frequency and the threshold speed of instability. The rotordynamic performance of HB-MFB rotor system is sensitive with some of the bearing parameters, like mesh density and bearing clearance.

Evolution of flow characteristics in a centrifugal compressor with an increase in operating speed

Developments in materials, manufacturing and computing methods have catalysed the generation of efficient compressor designs with higher specific power outputs. Centrifugal compressors have become pervasive in environments demanding a combination of higher power with smaller sizes such as unmanned aerial vehicles, micro gas turbines and turbochargers. These compressors are expected to perform optimally in a range of operational speeds and mass flow states with low acoustic emissions. The impact of operating speed on the flow and acoustic characteristics of a ported shroud compressor has been explored in this work. The operation of the open and blocked configurations of the compressor at the design and near surge points each of a lower and a higher speedline was numerically and experimentally investigated. Comparing the results, the model was shown to predict the operation of the compressor for both configurations at the investigated operating points satisfactorily in terms of both performance and dominant acoustic features. With an increase in the velocity and the Mach number due to increased operational speed, changes in the flow behaviour in the inducer and diffuser were observed. An increase in operational speed was shown to generally increase the overall acoustic emission of the compressor for both configurations. The number of distinct tones in the acoustic output and their magnitude were also seen to be a function of operating speed.

Performance Analysis of Encoderless DTC of IPMSM for Wide Operating Range

In this paper, a look-up table-based direct torque control (DTC) of interior permanent magnet synchronous motor (IPMSM) drive is reported. An approach is made to develop a sensorless four-quadrant electric drive for a wide operating speed range. In order to ensure efficient operation of IPMSM, maximum torque per ampere and field weakening algorithms are employed. The constraints associated with pure integrator in DTC are discussed, and an adaptive controller-based approach to estimating stator flux is proposed. A bidirectional DC–DC converter is implemented to allow four-quadrant operation of drive. In order to realize sensorless operation, stator current-based model reference adaptive control is employed to estimate the motor speed. Speed reversal, torque reversal, above-base-speed operation and low-speed operation of IPMSM drive are considered in this paper. The proposed algorithm is implemented in the MATLAB and Simulink, and the soundness of the suggested estimator is presented by simulation results.

Ignition timing and compression ratio as effective means for the improvement in the operating characteristics of a biogas fueled spark ignition engine

In the current investigation, a four stroke, variable speed, single cylinder, variable compression ratio (VCR) SI engine is operated with raw biogas at wide open throttle (WOT) condition and at five different CRs ranging from CR 10 to CR 14 over the operating speed range of the engine. The ignition timing (IT) of the engine is also varied from 23○CA to 47○CA before top dead centre (bTDC) at each operating CR. The optimized operating CR and IT of the engine are obtained through series of experiments and its effects on the performance, combustion and emission characteristic are analysed herein. The rise in operating CR from CR 10 to CR 12 enhanced the power output and efficiency of the biogas fueled SI engine by 12.72% and 5.68%, respectively and reduced fuel consumption by 5.42% at 1400 rpm. Enhancing the CR from CR 10 to CR 12, limited the intensification of NOx and unburnt hydrocarbon emission by 10.17% and 15.6%, respectively at 1400 rpm. Hence, CR 12 is recommended as the optimum CR and its combination with 1400 rpm and WOT setting is recommended as the best operating condition of the engine.

Operation Method of Non-Salient Permanent Magnet Synchronous Machine for Extended Speed Range

This paper proposes an operation method for the extended speed range of a surface-mounted permanent magnet (SPM) synchronous machine. The proposed method is based on a novel winding changeover scheme. The SPM machine has low synchronous inductance and hence poor field weakening capability. To enhance its field weakening capability, the permanent magnet's flux linkage can be reduced by performing a winding changeover. The proposed operation method increases the base speed of the machine by 3.83 times. In contrast to available two-inverter schemes with four thyristor switches, the proposed scheme utilizes a single-inverter topology drive and six bidirectional switches for the winding changeover. The machine works in two modes: cumulative and differential. In the cumulative mode, winding has a high induced back electromotive force (EMF), whereas in the differential mode, it falls by 3.54 times. The base speed increases approximately by the same ratio. After the mode switch, field weakening control is applied to the machine to further increase the speed range to 3.83 per unit. The proposed operation method was simulated in a commercial two-dimensional finite element method software in both modes under no-load and load operating conditions. The transient analysis was performed during the winding changeover, and speed range operation analysis was also carried out. The experimental results are provided to verify the extension of the speed range operation of the proposed novel winding changeover scheme for an SPM machine.

Acoustic Noise Mitigation of Switched Reluctance Machines with Windows on Stator and Rotor Poles

Switched reluctance machines (SRMs) have been studied by many researchers as an alternative to the other types of electrical machines for use in electric and hybrid vehicle applications. SRMs are fault tolerant and have wide speed operating range. However, they suffer from several disadvantages, including high vibration, acoustic noise, and torque ripple. In this article, the placement of rectangular windows in both the rotor and stator poles is proposed to reduce the vibration and acoustic noise of SRMs. An iterative optimization algorithm in a wide speed range of operation using finite-element analysis (FEA) tools provides the best position and dimension of window design parameters. Multiphysics FEA is also performed to predict the vibration and acoustic noise of the optimized design. The results of this study present that placing windows in both the stator and rotor of the SRMs can significantly reduce the acoustic noise compared with the baseline SRMs. Based on the simulation results, the optimum design has been constructed as a prototype and tested in a wide speed operating condition. The simulation and experimental test validation results prove the effectiveness of the proposed design in mitigating the acoustic noise and vibration.

A Wound-Field Pole-Changing Vernier Machine for Electric Vehicles

This paper proposes a wound field pole changing vernier machine with fractional slot concentrated winding for electric vehicles application. The main aim of the paper is to utilize the advantages of a vernier machine and a wound field synchronous machine in a single topology using a fractional slot concentrated armature winding. The proposed machine operates in a vernier mode at low speeds and a wound-field synchronous mode at high speeds to utilize the merits of both a vernier machine and a wound-field synchronous machine. The topology, operating principle and pole-changing method of the proposed machine are explained initially. Then, finite element analysis (FEA) is utilized to study the electromagnetic characteristics such as back EMF, torque, wide speed range operation and efficiency of the proposed topology in two modes. Further, a prototype of the machine is manufactured and the FEA results are validated through experiments. The FEA and experiment results show that the proposed machine is a promising candidate for electric vehicles application.

Extending the Linear Modulation Range to Full Base Speed Independent of Load Power Factor for a Multilevel Inverter Fed IM Drive

In this article, a method is proposed for the first time, to increase the linear modulation range till full base speed irrespective of load power factor for a multilevel inverter fed induction motor drive. A five-level inverter with a single dc source is used for the proposed scheme. Using this method, linear pulsewidth modulation (PWM) operation of the inverter can be achieved till peak phase fundamental voltage of 0.637 V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dc</sub> without exceeding machine phase voltage rating. This method eliminates all the lower order harmonics from machine phase voltage till the full speed range of operation. The proposed five-level inverter scheme is realized by cascading a two-level inverter with a capacitor fed H-bridge, feeding open-end induction motor drive from one end and a capacitor fed two-level inverter from the other end. The proposed scheme uses space vector redundancy to balance all the capacitors during its operation. Operation of the proposed drive is analyzed extensively for normal five-level operation as well as during the extended modulation range. Experimental results for steady state and transient state operation are presented to validate the proposed scheme.

Comparative study of hybrid-PM variable-flux machines with different series PM configurations

Aiming at extending the operating speed range and increasing the machine efficiency, three series-configuration hybrid-permanent-magnet variable-flux machines (HPM-VFMs) with both low and high coercive-force magnets are proposed. The magnetization characteristics of the machine with different dimensions of the high coercive-force (HCF) magnet are investigated. Then, in order to improve the contribution rate of the HCF magnet, two improved topologies are presented. The electromagnetic characteristics of the two proposed machines, including back electromotive force (EMF), maximum torque characteristics, magnetization state (MS) variation range and magnetic field distribution, are comprehensively analyzed and compared. The influence of different types of windings on the performance of the machine is also investigated. Finally, the torque-speed curves of the machine under different MSs are given by finite element method (FEM). The results show that the HPM-VFM can operate over a wide-speed range with high efficiency.

IMPROVING THE REACTIVE POWER CAPABILITY OF GRID CONNECTED DOUBLY FED INDUCTION GENERATOR

Due to increasing wind power generation in the electric power system, the reactive power generation by the wind farms is a major concern during both steady state and faulty conditions. This work, first, presents the reactive power capability (RPC) curve of doubly-fed induction generator (DFIG) considering three limitations (rotor voltage, rotor current and stator current) for reactive power production/consumption, for the complete operating range which is obtained by optimal rotor speed employing maximum power point tracking (MPPT) algorithm. It is established that the total reactive power generation is limited by rotor voltage at low speeds and by rotor current at higher speed. However, the total reactive power consumption is limited by stator current, for entire operating region. Selection of partial rated converter rating is crucial in terms of cost, efficiency, operating speed range and reactive power capability. The effect of converters rating on the enhancement of RPC of doubly fed induction generation is analyzed. Complete capability curves of DFIG for different stator voltages are developed considering grid-side converter (GSC) contribution towards reactive power capability.

Suppression of Synchronous Current Using Double Input Improved Adaptive Notch Filter Algorithm

In order to suppress the influence of the synchronous vibration generated by the unbalance of magnetically suspended control moment gyro on the attitude control accuracy and stability of the satellite platform, this article first introduces the working principle of the magnetically suspended high-speed rotor system, and also establishes the dynamic model of the magnetically suspended rotor with unbalance mass. At the same time, the main sources of unbalance vibration are also analyzed. Finally, an improved adaptive notch filter based on double input is designed. The filter takes the rotor radial X, Y two-channel displacement sensor signals as inputs, and uses the characteristics orthogonal to each other to simultaneously enter the system. The rotor can be automatically balanced by adjusting the convergence factor and the compensation angle to adaptively suppress the synchronous current in a widely operating speed range. Simulation and experimental results show that the method can effectively eliminate the synchronous current in a widely operating speed range and improve the stability of the system. This research on the microvibration of the rotor is of great significance and application value.

A Comprehensive Review of State-of-the-Art Parameter Estimation Techniques for Permanent Magnet Synchronous Motors in Wide Speed Range

Permanent magnet synchronous motor (PMSM) drive has emerged as one of the most preferred motor drives for industrial applications owing to its distinguished advantages, such as high torque density, high efficiency, and wide speed range operation. However, accurately updated knowledge about the PMSM parameters is crucial to designing a high-performance trajectory tracking controller. This article presents a state-of-the-art comprehensive review and up-to-date progress of the offline and online parameter estimation techniques of the PMSM drives. First, the problems associated with parameter estimation of the PMSM are systematically summarized to identify the parameters having fast and accurate convergence. Second, the offline parameter estimation techniques are categorized based on the frequency and time responses. Third, the recent advances and developments of the online parameter estimation techniques for PMSMs are assessed. Finally, there is a discussion of extensive industrial applications and future research trends for the parameter estimation techniques.

Investigation of Aluminium and Copper Wound PMSM for Direct–drive Electric Vehicle Application

This paper investigates aluminium and copper windings for a permanent magnet synchronous machine (PMSM) developed for direct–drive electric vehicle (EV) application. Previously, studies have been conducted on comparison of these windings in terms of thermal and electrical conductivity, cost and mass density. However, the impact of these windings on the machine’s performance in terms of efficiency and torque has not been analysed. In this paper, for the same machine volume and geometry, a comparative analysis of PMSMs with copper and aluminium windings has been performed in terms of efficiency, torque, weight, operating speed range, ohmic losses and temperatures. Furthermore, as these machines are developed for direct–drive EV application, drive–cycle-based analysis was conducted for urban and highway cycles for a 2013 Ford Focus vehicle dynamics model. For these drive cycles, analysis in terms of torque speed characteristics and maximum energy density efficiency for both the machines has been performed.