Motor Start-up Research Articles

Identification of Voltage Sag Sources in the Electrified Railway Power Supply System Based on CNNs

In order to solve the problems of long classification time and low accuracy of traditional voltage sag source identification methods, on the basis of CNNs, the author conducts an in-depth study on the identification of voltage sag sources in the electrified railway power supply systems. Firstly, study and research from three methods of line fault analysis, simulation verification method, and power quality analysis method are conducted. In order to improve the classification and identification of compound-voltage sag sources when the distribution network contains harmonics, the author proposes a new method for the classification and identification of compound-voltage sag sources based on the eigenvalue synthesis method. Among them, according to the different voltage sag waveform characteristics caused by different composite voltage sag sources, the three-phase voltage unbalance is defined, and the result is obtained by combining the compound-voltage sag source including single-phase grounding with the voltage sag source compounded by induction motor startup and transformer input. After experiments and research, the proposed method is verified by simulation experiments, the results show that the method can classify and identify the types and fault sequences of the compound-voltage sag sources well, and the identification accuracy rate is higher than 96%.

DC Motor Control Technology Based on Multisensor Information Fusion.

To solve these uncertain problems by studying the motor fault diagnosis technology, so as to ensure the normal operation of the motor equipment is the primary problem to be solved in the field of motor fault diagnosis. The traditional DC motor is one of the most widely used motors at present. It has excellent speed regulation performance and is easy to control. It is widely used in applications that require high motor startup and speed regulation characteristics. This research mainly discusses DC motor control technology. Evidence theory can combine various fault information at different levels to enhance mutual support between pieces of evidence, thereby improving the accuracy of motor fault detection. Based on the steps of signal processing, feature extraction, feature dimensionality reduction, and state recognition, the research on the state recognition method of belt conveyor drive motor based on multisource information fusion is carried out. By studying the multisource information fusion, this paper proposes a two-stage belt conveyor drive motor information fusion model based on the optimal D-S evidence theory. The correct identification rate of broken rotor bars during fault monitoring is 99.8%. This method divides the specific motor fault feature set into multiple fault subspaces and uses different diagnostic neural networks and different fault feature parameters for local diagnosis, respectively. The scheme designed in this study significantly improves the recognition accuracy of the motor in the same working condition and under variable working conditions. The drive motor state recognition and intelligent decision-making system designed by combining the results of multisource information fusion can effectively describe the fault type and has strong operability.

Treatment Strategy Research on a Squirrel-Cage Induction Motor with Broken Rotor Bar Faults.

Squirrel-cage induction motors are increasingly displaying a broken rotor bar fault, which represents both a technical problem and an economic problem. After confirming that the broken rotor bars do not affect the normal start-up and basic working performance of the squirrel-cage induction motor, this paper focuses on the loss and efficiency changes of the motor brought about by the broken rotor bar fault. Using finite element simulation and experimentation, various losses like stator copper loss, iron loss, rotor copper loss, mechanical loss and additional losses, total loss and efficiency are obtained. By combining price and cost factors, the cost-effective measures that can be taken after the occurrence of different degrees of broken bars are evaluated here to provide guidance for correctly handling this problem.

Inverse thresholding to spectrogram for the detection of broken rotor bar in induction motor

This paper introduces a reliable approach based on start-up transient analysis using inverse thresholding to spectrogram for early detection of a broken rotor bar fault in an induction motor. The investigation has been done in the time–frequency plane since it is based on the non-stationarity assessment of fault frequencies. Typically, time–frequency analysis is carried out in the presence of the fundamental, resulting in the fault features appearing unnoticed. The proposed technique addresses this issue by weakening the fundamental, making fault features more clearly apparent. To achieve this, inverse thresholding to spectrogram has been utilized for motor start-up current. In addition, a quantitative analysis of machines’ health has also been offered. A health score has been calculated based on the spectral entropy in the start-up current to quantify the condition of the motor. To examine the rotor fault, a Finite Element Model (FEM) of the machine is simulated in the ANSYS 2D workbench. The suggested method has been validated with simulated data in multiple simulation scenarios with varying load torques to demonstrate the method’s efficacy. Finally, the diagnosis method is tested against a publicly available data set related to the rotor bar fault.

Optoelectronic system for controlling an alternating current motor. Electrical and electronic design

A control system for a three-phase induction motor was designed with the use of optoelectronic components and methods. Motor speed was controlled by changing supply voltage frequency. This solution ensures a wide range of rotational speeds, constant torque and effective start-up of an induction motor. The designed motor is supplied with direct current converted to three-phase alternating current. The adopted solution relies on renewable sources of energy to produce DC power. The designed electric motor is controlled by changing supply voltage frequency. Input voltage with the desired waveform is generated by the motor’s electronic system that relies on two microcontrollers. The presented solution features a user interface.

A new starting capability assessment method for induction motors in an industrial islanded microgrid with diesel generators and energy storage systems

Induction motor (IM) startup can cause voltage dip disturbances and is detrimental to the stable operation of industrial islanded microgrids. Firstly, this study investigates the active power characteristics of the diesel generator and battery energy storage system (BESS) with IM based on the steady-state equivalent circuit to determine the starting capability of an islanded microgrid. Then, the starting conditions and the stable feasible region of the diesel generator and BESS with IM are further deduced considering different mechanical power models. A new Starting Capability Index (SCI) for the IM of the islanded microgrid with diesel generators and BESS is proposed to assess the microgrid's overall starting capability and arrange the starting sequence during motor startup in different locations of islanded microgrids. Based on SCI, a strategy to determine the starting sequence of multiple IMs in the islanded microgrid is proposed to improve the quantities of IM startups and the microgrid's dynamic performance. Two cases of an islanded microgrid with diesel generators and BESS are tested using MATLAB/ SIMULINK to verify the effectiveness of the proposed methods.

A Novel Step Current Excitation Control Method to Reduce the Torque Ripple of Outer-Rotor Switched Reluctance Motors

Featured in low-speed and high-torque operation, outer-rotor switched reluctance motors (OSRMs) have the potential to be widely deployed in low-speed commuter and logistics vehicle applications. In this paper, a five-phase OSRM and the control method featuring torque ripple reduction has been proposed, which can be applied as the wheel hub motor in the electric vehicles. The simulation was carried out to analyze the OSRM operation. The electromagnetic characteristics of single-phase and two-phase hybrid excitation mode, as well as step current excitation mode, were compared and analyzed. To solve the problem of the large torque ripple of OSRMs under traditional excitation modes, the torque ripple suppression method based on step current excitation was also studied. The experiment design, including motor start-up control, speed control, and torque ripple reduction, are presented to verify the system torque ripple mitigation method.

Research on start-up characteristics of electric motor driven reversely by hydraulic pump/motor

The series electro-hydraulic hybrid powertrain can improve the power characteristics of battery rail vehicles (BRVs) while also extending battery life and increasing vehicle mileage. A novel electric motor start-up method using the hydraulic pump/motor to reversely drive the permanent magnet synchronous motor (PMSM) to restart at a speed is proposed based on the energy reverse transfer characteristics between the electric motor and hydraulic pump/motor. PID controls the reverse driving process of the hydraulic motor. The zero vector voltage (ZVV) method is used to determine the initial speed and rotor position of the motor restart at a speed. The electric motor speed control adopts the speed sensorless space vector pulse width modulation (SVPWM) control based on the back-electromotive force (EMF) integration method. The simulation models are carried out in MATLAB/Simulink and AMESim and built a special test platform. The results show that the method for controlling electric motor restart is feasible and effective. The start-up current of the electric motor is related to its initial speed. The closer the initial speed is to its target speed, the smaller its start-up current is, the faster the electric motor reaches the stable target speed.

Conformable fractional order controller design and optimization for sensorless control of induction motor

PurposeIn recent years, use of sensorless control methods for electrical motor-based variable speed drive systems has been increasing rapidly to compensate the increasing costs in industrial systems. Also, use of induction motors is popular for a long time to decrease the cost of these industrial systems. This study aims to design an effective controller to improve the sensorless speed control performance of induction motor. To achieve this, a conformable fractional order proportional integral (CFOPI) controller is designed.Design/methodology/approachThe system is modeled based on small signal analysis by using the input–output data, experimentally. To do this, system identification toolbox of Matlab is used. The proposed controller is established on conformable fractional integral approach proposed by Khalil et al. (2014). CFOPI controller coefficients are optimized using particle swarm optimization method on the created small signal-based simulation model of the system to minimize the integral time absolute error. To prove the success of the proposed method, a traditional fractional order proportional integral (TFOPI) controller is tested under the same experimental system with the CFOPI controller.FindingsTFOPI and CFOPI controllers are tested with the optimum parameters. Reference and actual speed trends are obtained for both methods. In induction motor start-up test, settling-times are measured as 8.73 and 8.44 s and steady-state oscillations are 2.66% and 0% (almost) for TFOPI and CFOPI controllers, respectively. In variable referenced speed tracking test, CFOPI performs well at all speed levels, while TFOPI fails to reach the reference speed at most speed levels.Practical implicationsProposed CFOPI control method can be easily implemented in industrial systems, thanks to its simple algorithm. digital signal peripheral interface controller (dsPIC) based driver circuit with designed CFOPI controller used in this study can be applied directly to industrial systems such as elevators, conveyors, cranes and drills. Moreover, it can improve the performance of induction motor-based variable speed drive systems.Originality/valueThe proposed method provides robust performance for induction motor used in control systems. Additionally, it does this by using less complex algorithm written on the processors according to the traditional fractional order controllers.

Fault Diagnosis of Rotor Broken Bar in Induction Motor Based on Successive Variational Mode Decomposition

When an induction motor is running at stable speed and low slip, the fault signal of the induction motor’s broken bar faults are easily submerged by the power frequency (50 Hz) signal. Thus, it is difficult to extract fault characteristics. The left-side harmonic component representing the fault characteristics can be distinguished from power frequency owing to V-shaped trajectory of the fault component in time-frequency (t-f) domain during motor startup. This article proposed a scheme to detect broken bar faults and discriminate the severity of faults under starting conditions. In this scheme, successive variable mode decomposition (SVMD) is applied to analyze the stator starting current to extract the fault component, and the signal reconstruction is proposed to maximize the energy of the fault component. Then, the quadratic regression curve method of instantaneous frequency square value of the fault component is utilized to discriminate whether the fault occurs. In addition, according to the feature that the energy of the fault component increases with the fault severity, the energy of the right part of the fault component is proposed to detect the severity of the fault. In this paper, experiments are carried out based on a 5.5 kW three-pole induction motor. The results show that the scheme proposed in this paper can diagnose the broken bar faults and determine the severity of the fault.

Experimental and numerical study on self-sustaining performance of a 30-kW micro gas turbine generator system during startup process

The safe startup of micro gas turbine (MGT) generator system is the premise of normal operation. The whole start-up process contains motor startup, ignition, speed acceleration, motor switching to generator and power acceleration. Motor switching to generator happens at the self-sustaining state, which is significant to safe start-up process. However, characteristics of MGT generator system at self-sustaining state are hardly to investigate due to the lack of performance maps and complete experiments. Therefore, this work analyzed start-up schedule and presented a theoretical and experimental study on the self-sustaining performance of MGT generator system, based on the self-designed 30 kW MGT generator system built in Jiangjin Turbocharger Plant, China. The self-sustaining speed boundary and fuel consumption area is determined from the aspects of safe startup. A novel principle for determining the self-sustaining point (SSP) is proposed. Results show that the self-sustaining state can be achieved only when speed is over 26,750 rpm, and the SSP is determined at the speed of 30,750 rpm based on the proposed principle. Finally, the self-sustaining TIT and natural gas flow are compared with the experimental data, with two relative errors both almost within 4%. This method is instructive to the MGT generator system startup process.

Dynamic Simulation of High-Speed Induction Motor

In the drives of high-speed devices, such as a blood centrifuge, dynamic states also play an important role in terms of the time and quality of the tests performed. The article presents the application of modified equations resulting from the mathematical model of an induction motor to model dynamic phenomena during motor start-up, both with mains supply and with frequency start-up. The applied solution considers the phenomenon of current displacement in the rotor bar and the phenomenon of saturation. The comparison of the obtained results with the experiment shows that the method is sufficiently accurate. The obtained results can also be extended to higher power machines and to modeling other dynamic states.

Start-up of PM synchronous motors

Start-up of PM synchronous motors

Diagnosis of Broken Rotor Bars during the Startup of Inverter-Fed Induction Motors Using the Dragon Transform and Functional ANOVA

A proper diagnosis of the state of an induction motor is of great interest to industry given the great importance of the extended use of this motor. Presently, the use of this motor driven by a frequency converter is very widespread. However, operation by means of an inverter introduces certain difficulties for a correct diagnosis, which results in a signal with higher harmonic content and noise level, which makes it difficult to perform a correct diagnosis. To solve these problems, this article proposes the use of a time-frequency technique known as Dragon Transform together with the functional ANOVA statistical technique to carry out a proper diagnosis of the state of the motor by working directly with the curves obtained from the application of the transform. A case study is presented showing the good results obtained by applying the methodology in which the state of the rotor bars of an inverter-fed motor is diagnosed considering three failure states and operating at different load levels.

Performance Improvement of Grid-Connected Induction Motors through an Auxiliary Winding Set

A technique to improve the performance of grid-connected induction motors by exploiting an auxiliary winding set is proposed in this paper. This auxiliary winding features the same distribution of the main winding, although with a reduced number of turns and it is fed by an inverter a fraction of the power in comparison with the rated size of the induction motor. As shown in the paper, through the auxiliary winding, it is possible to set the machine power factor, increasing the efficiency of the power conversion system and mitigating speed oscillations due to torque disturbances. A mitigation of the grid current peaks due to motor start-up is obtainable. First, the proposed technique is theoretically introduced, then a feasibility assessment is accomplished by simulations.

Thermal problems during start-up of cage induction motors

Thermal problems during start-up of cage induction motors

유도전동기 기동용 변압기의 용량 산정에 관한 연구

Induction motor have the advantage of simple structure, robustness, low-price and easy maintain. Therefore, it is most widely used in the industrial field. The induction motor has two disadvantages when starting. The first is that the power factor is low and the second is that the voltage drop due to the high starting current is large. Therefore, many studies have been conducted to reduce such shortcomings. If the voltage drop on the same bus increases, it affects other loads as well, so the system should be designed so that the voltage drop is as low as possible. Although the previous research focused on improving the induction motor start-up method, this research introduces a method that can improve the voltage drop through the change of the capacity of the transformer. Therefore, in this study, we applied the calculation method of the capacity of the emergency generator to the transformer and analyzed the voltage drop that occurs automatically when the induction motor is directly started. In order to verify the analysis, it was confirmed that the actual circuit was very similar as a result of comparative analysis by applying an analytical method and an analysis program.

Development of an optimal control system with pulse control in the rotor circuit for cargo movement mechanisms

The paper analyzes the methods of starting an asynchronous motor with a phase rotor. The control system used on the object under consideration, the mechanism of cargo movement, is obsolete. Current problems in modern production are measures aimed at energy saving at all stages of production, as well as ensuring the necessary dynamic indicators of control systems. In this paper, several control systems for the mechanism of cargo movement are considered and investigated. The optimal control system for several indicators is proposed. The Matlab Simulink package simulates various start-up methods, namely: direct start-up from the network, rheostatic start-up of an asynchronous motor with a phase rotor, pulse start-up of an asynchronous motor with a phase rotor, asynchronous-valve stage and asynchronous-valve stage with pulse regulation. According to the obtained graphs, a comparison is made and conclusions are drawn about the advantages and disadvantages of each of the start-up methods, as well as graphs of the consumption of active and reactive energy of each of the methods and the most energy-efficient control method is identified.

Phase Inductance and Rotor Position Estimation for Sensorless Permanent Magnet Synchronous Machine Drives at Standstill

Sensorless control is a common control method used in variable speed drive applications with permanent magnet synchronous machines (PMSMs). In these drive systems, phase inductance (i.e., ${q}$ - and ${d}$ -axis inductance) is the key parameter in designing current controllers. Additionally, the rotor position is essential for coordinate transformation during the motor startup. This paper presents the two offline methods of 1) line-to-line voltage injection and 2) stator qd voltage injection of sensorless PMSM drives for the estimation of phase inductance and initial rotor position, respectively. A distinct feature of the proposed methods is that they estimate both inductance and rotor position using the same algorithm. These methods were experimentally verified using an interior PMSM (IPMSM) and a surface-mounted PMSM (SPMSM). Because of the use of a least-squares algorithm, only a limited number of voltage vectors are required to achieve reasonable accuracy for measuring inductance. However, the accuracy of the estimated position was linearly proportional with the number of voltage vectors injected. Furthermore, the position error for IPMSM was found to be smaller than that for SPMSM.

A Novel PID Optimization Technique for Synchronous Motor Start-Up

A Novel PID Optimization Technique for Synchronous Motor Start-Up