Motor Terminal Voltage Research Articles

Sensorless control of submersible permanent magnet synchronous motor under long-line cable model

In the process of oil production, the submerged oil motor works 1-3 km downhole and is connected to the inverter by a long-wire cable, which generates overvoltage at the motor end due to the problem of matching the impedance of the motor with the impedance of the power cable. The downhole environment is not suitable for the installation of precision devices, such as position sensors. To solve these problems, a sensorless control method of submerged oil motors based on a high-frequency voltage injection method is proposed. A motor terminal voltage and current observer under a long-wire cable model is designed to estimate the actual values of motor terminal voltage and current by collecting the voltage and current at the inverter terminal. A three-level inverter is used to provide energy to the submersible oil electric pump through the long-wire cable, which can effectively suppress the motor terminal overvoltage compared to the two-level inverter. The control algorithm is verified by modeling the whole system using simulation software.

Wireless power transfer system with dual‐frequency operation in transmitter side for motor control application

AbstractIn this paper, a transmitter‐side control method is proposed in inductive wireless power transfer (I‐WPT) model for the speed and power control of a single‐phase induction motor (SPIM). Resonant tanks with an electronic driving mechanism are used in the proposed configuration. The receiver side employs two resonant circuits with two full wave rectifiers, comparator, and two gate drivers for the management of the motor speed and power. The resonant circuits and electronic motor drive are presented through detailing the mathematical model and system design. In addition, a comparative section of the proposed model with the previous art is introduced to address the contributions of the paper. Moreover, a prototype model of the proposed topology has been created in simulation environment and tested in a variety of scenarios. The proposed I‐WPT model has a power rating of 140 W, whereas the SPIM has a power rating of 120 W. At full power operation, a 130 W power is supplied from the source during 118 W power consumption of SPIM, indicating that the system's efficiency is over 90%. The motor speed control has been tested by lowering the operation frequency of the motor terminal voltage from 60 to 40 Hz and from 40 to 20 Hz. The dynamic motor power has been also analyzed by reducing the load power from 100% to 70%. The findings reveal that the proposed transmitter‐side controlled I‐WPT system operates in a wide range of circumstances.

Improved Performance of Direct Torque Control with PMSM compared to DTC with Induction Motor

For induction motor torque control, direct torque control is becoming the industry standard. This paper proposes a switching loss minimization technique for improved Direct Torque Control (DTC) of permanent magnet synchronous motors in order to increase the drive system's steady-state and dynamic results. Direct torque control (DTC) of a voltage source inverter-supplied PMSM is a simple scheme that requires little computation time, can be implemented without speed sensors, and is unaffected by parameter variations. In theory, the motor terminal voltages and currents are used to calculate the flux and torque of the motor. A voltage vector is chosen to restrict the flux and torque errors within their flux and torque hysteresis bands based on the instantaneous torque and stator flux magnitude errors, as well as estimates of the flux position. The electromagnetic torque, rotor speed, and stator current of DTC with PMSM and DTC with IM were successfully calculated using Total Harmonic Distortion (THD) in this article. As compared to DTC with IM, DTC with PMSM reduced THD by 12 percent in torque, speed, and stator current [21]. Switching Losses Minimization Technique by THD Minimization is used in this article. Since transistors are only switched when necessary to maintain torque and flux within their hysteresis limits, switching losses are minimised, resulting in increased efficiency and lower losses. Matlab SIMULINK has experimentally confirmed direct torque regulation with PMSM and IM.

A New ${\rm{\delta }}$-MRAS Method for Motor Speed Estimation

This letter introduces a new method to estimate the motor speed based on the Model Reference Adaptive System (MRAS) technique. The novelty of the proposed MRAS control structure relies on using the motor input impedance angle as a reference state variable to estimate the motor speed. In this context, the reference angle is obtained from measuring the angle between the motor terminal voltage and current vectors using a double-structure Phase Locked Loop (PLL). The tunable angle is instantaneously calculated using the per-phase motor equivalent circuit. Having the impedance angle as the only candidate for the proposed scheme inherently decouples the reference and the adaptive models. This decoupling resulted in obtaining a superior performance at low, high, and zero speeds. The simplicity of the reference and the adaptive schemes ease the analysis, design, and implementation. The introduced speed estimation concept is validated under different scenarios of operating conditions.

Multimode Control of PV-STATCOM for Stabilization of Remote Critical Induction Motor

New multimode control for PV-STATCOM operation of a photovoltaic (PV) solar plant is presented for preventing the instability of remotely located critical induction motors (IMs) whose shutdown during faults can cause significant financial loss to industries. The proposed control operates in four different modes that are determined by PV plant voltage, IM terminal voltage, and high-voltage ride-through limits of the PV plant. The proposed PV-STATCOM control ensures the stability of remote IM even if a PV plant is located up to 40 km away, a very large delay occurs in communicating motor terminal voltage to PV plant, and the system parameters and operating conditions vary over a wide range. The remote PV-STATCOM provides a similar motor stabilization as locally connected STATCOM. Furthermore, the PV plant with PV-STATCOM control can stabilize remote IM, while the dynamic current injection by PV plant as specified in grid codes' fails to do so. The effectiveness of the proposed PV-STATCOM control is examined on a realistic distribution feeder in Ontario and is field demonstrated on a 10 kW PV plant in the network of Bluewater Power Distribution Corporation, Sarnia, ON, Canada. The proposed PV-STATCOM control is a substantially cost-effective alternative to the installation of expensive STATCOMs or static var compensators for stabilizing critical motors.

Research on multi-core DSP cooperative control system in environmental protection equipment

Traditional multi-servo motor control systems have the problems of poor output stability in environmental protection equipment, weak robustness, and low control ability. Based on this, the research of multi-servo motors control systems based on FPGA are proposed. The paper Construct a parameter distribution models on multi-servo motor control, using motor terminal voltage, current, and back-EMF as control constraints, calculate the difference between the output currents of the multi-servo motors, and construct a saturation function to analyze the multi-servo motor control objective function. Sampling phase current signal and PWM duty cycle as modulation parameters, combined with fuzzy adaptive PID control method to control the output robustness of multiple servo motors, calculating the equivalent mechanical power and equivalent electromagnetic power of multiple servo motors. The optimized parameter adjustment method performs self-tuning processing of the motor output, and the transient stability adjustment of the multi-servo motor is performed based on the method of the average terminal voltage analysis to realize the optimal design of the multi-servo motor control law. The test results show that the output stability of the output of the multi-servo motor control system using this method is better, the motor control is more robust and the control ability is higher.

An analysis of generator trip caused by mistransmitting high temperature signal from excitation transformer

The excitation transformer is a device that specifically provides three-phase AC excitation power for the generator excitation system. The excitation system converts the three-phase power to the generator rotor DC power through the thyristor to form the generator excitation magnetic field, which is adjusted by the excitation system thyristor trigger angle, to achieve the purpose of adjusting the motor terminal voltage and reactive power. This article analyzes an accident in which the excitation transformer high temperature signal is erroneously caused to cause the unit to trip. The unplanned shutdown accident is specifically analyzed from the aspects of on-site situation investigation, cause analysis, main problems exposed, treatment and preventive measures.

Estimation of Rotor Position for Permanent Magnet Synchronous Motor at Standstill Using Sensorless Voltage Control Scheme

The zero-speed rotor position estimation in surface mounted permanent magnet synchronous motor (SM-PMSM) represents a challenge due to the weak magnetic saliency in this type of motors. This article presents a new method to estimate the initial rotor position of SM-PMSMs more simply and more accurately without any form of position or current sensors. It achieves this goal through an injection of three short width pulses and employing only the measurements of the motor terminal voltage responses, which fluctuate sinusoidally with the rotor position. Thereby, memory addresses, or dimensions of a look-up table, were created from the readings of the measured voltages. The memory was primarily loaded with 360 angles, each represents ${1^{{\bf o}}}$ angle of rotor positions. The simulated MATLAB model and experimental results demonstrate the advantages. Comparing with the previous related publications, this research work has fulfilled two main contributions. The first is in achieving a rotor position estimation of ${1^{{\bf o}}}$ resolution. The second is in eliminating the technique needed for detection of the rotor magnet polarity. The measured rates of error for the MATLAB model and the practical model were 2% and 5%, respectively.

Analysis and Design of a Sine Wave Filter for GaN-Based Low-Voltage Variable Frequency Drives

Gallium nitride (GaN) devices have been widely adopted to achieve high efficiency and high power density as alternative solutions to silicon devices. When the GaN power devices are used for variable frequency drive (VFD) systems, the high dv/dt pulses at the motor terminal, which induce shaft voltage and common mode current, should be carefully considered to ensure system reliability. Although the high dv/dt issues can be mitigated with a dv/dt filter method, it leads to performance degradation depending on cable length. Meanwhile, a matrix converter also becomes a next-generation power converter for the VFDs which has a regeneration capability and unity power factor. Thus, this paper discusses the GaN-based matrix converter for the VFD as a study case considering the motor terminal voltage quality and the common mode current. Also, a sine wave filter is adopted to cope with the terminal voltage quality irrespective of cable length. The optimized design procedure of the sine filter considers practical issues. Experimental results are presented to suggest a suitable solution for the GaN-based VFDs in accordance with the cable length.

Power Capability Improvement of Interior Permanent Magnet Synchronous Motor Drives Using Capacitive Network

This paper proposes a method to boost the terminal voltages using a capacitive network. The boosted voltage can improve the power capability of an interior permanent magnet synchronous motor (IPMSM). In the conventional drive system fed by a voltage-source inverter, the terminal voltages of the motor are limited by the dc-link voltage. Such a voltage limitation reduces the torque capability at high speeds. Thereby, the maximum output power is limited. To overcome this feature, series capacitor network between the inverter and the motor is introduced in the proposed IPMSM drive system. The series capacitors boost the motor terminal voltages higher than the inverter voltages to increase the rated speed, resulting in improved power capability. The rated speed in the proposed drive system can be redefined to the desired value through a capacitive network. The enhanced power capability and design freedom in the rated speed are particularly advantageous in fan-load applications where the load torque is proportional to the square of speed. This article presents the structure, d–q equivalent model, operating characteristics, and operable area of the proposed drive. Experimental results are given to verify the feasibility and effectiveness of the proposed system.

Design and implementation of a test setup for electric mobility scooter for the disabled

In this study, a test setup was designed for three- and/or four-wheeled electric mobility scooter models used by disabled or old people. This system is composed of a test platform that enables measurement of vehicular velocity, a data acquisition card, and an interface prepared in the C# program. Using the data acquisition card that was designed, seven quantities, namely, battery and motor currents, battery and motor terminal voltages, wheel speed in revolution per minute, and ambient and motor temperatures, were measured instantaneously during the test procedure and transferred to a computer via a USB device. Using these data that were transferred, motor speed in revolution per minute, torque generated by the motor, motor shaft power, motor and driver efficiency, instantaneous velocity of the vehicle, and total distance covered information obtained from the moment the vehicle began to be used were computed in real time throughout the experiment in the interface prepared in the C#, and their graphs were drawn and recorded. Thus, the faults in the battery, motor, or driver of electric mobility scooters became easily detectable in tests conducted under various conditions such as different ambient temperatures, different user weights, and roads with different slopes.

Design and Control Method for a Surface-Mounted Permanent Magnet Motor Drive System With Passive Output Power Network

This article proposes a method to extend the operating area of the surface permanent magnet motor by inserting the passive power networks between the motor and the voltage source inverter (VSI). In the conventional motor drive system, since the operating area is limited by the maximum voltage, which is synthesized by the inverter, the output torque capability is reduced in the high-speed region. In order to extend the operating area, two types of passive power networks are proposed in this article. The power networks supply the reactive power to the motor for amplifying the motor terminal voltage. Due to the actions, the proposed motor drive system can utilize a higher maximum motor terminal voltage than that in the conventional drive systems. Depending on the network types, the operating point at which the maximum power or torque is generated is shifted to a high speed. The design, control, and analysis methods of the proposed system are presented in this article. The effectiveness of the proposed system is verified through the experimental results.

Performance Comparison Between Two-Level and Three-Level SiC-Based VFD Applications With Output Filters

One of the recent trends in power electronics field is to achieve high efficiency and compact size by using wide bandgap power devices such as silicon carbide (SiC) or gallium nitride switches. This paper compares the efficiency, the motor terminal voltage quality ( dv/dt ), and the common mode current of the SiC-based variable frequency drives (VFDs) according to the inverter topologies with and without the output filters. For this purpose, both the 2-level (2L) and 3-level (3L) topologies with SiC devices are built and tested. Here, the well-known 2L half-bridge inverter is compared with the well-known 3L T-type neutral point clamped inverter. A dv/dt filter and a sine wave filter have been discussed to satisfy the National Electrical Manufacturers Association standards as well. The experiments have been carried out with a 380-V/60-Hz, 3.7-kW induction motor and the custom designed power stages. Additionally, the experiments with both a 3-m and a 50-m cable length between the VFD and the induction motor are performed and reported.

A novel flux observer in sensorless PMSM drives

This paper investigates problems associated with direct torque control (DTC) of PMSM, such as the stator resistance variations, the integration drift and the integration saturation in order to reduce the system ripples. The standard particle filter (PF) algorithm was introduced to DTC system of PMSM. The motor terminal voltages and stator currents are the system input and output variables. and the two stator fluxes are used as system state variables. Then the flux can be estimated according to PF algorithm when the voltages and stator currents have been measured. The method was implemented in Simulink. The simulation results indicate that the system based on PF observer has good performance.

Observing the Permanent-Magnet Temperature of Synchronous Motors Based on Electrical Fundamental Wave Model Quantities

Estimating the magnet temperature of permanent-magnet synchronous motors on a model basis is the key for both the highest device utilization and preventing irreversible demagnetization. Using an exact flux linkage observer in the fundamental wave domain is an elegant way to indirectly retrieve the magnet temperature without requiring any additional sensors or signal injection. This contribution addresses several important issues for the real-world applicability of a permanent magnet temperature observer: thermal expansion affecting the radial air gap thickness, operation at low speeds or even standstill, and estimating the fundamental content of the motor's terminal voltage within one switching cycle. The proposed observer is comprehensively validated in the entire electrical and thermal operation range achieving a satisfying worst case error less than 10 K.

Switching losses minimization by using direct torque control of induction motor

Direct torque control is becoming the industrial standards for induction motor torque control. This paper presents switching loss minimization technique of improved direct torque control (DTC) of induction motor. Direct torque control (DTC) of an induction motor supplied by a voltage source inverter is a simple scheme that does not need long computation time, can be implanted without speed sensors and is insensitive to parameter variations. In principle, the motor terminal voltages and currents are used to estimate the motor flux and torque. Based on the instantaneous errors in torque and stator flux magnitude and estimates of the flux position, a voltage vector is selected to limit the flux and torque errors within their flux and torque hysteresis bands. In the conventional DTC, the selected voltage vector applies for the whole switching period, irrespective of the magnitude of the torque error. DTC drive gives variable switching frequency and high torque ripple. DTC gives torque and flux ripples because no any VSI states are capable to generate the exact voltage vector from switching table required to make zero both the torque electromagnetic error and the stator flux error. To minimize this problem, a torque hysteresis band with variable amplitude fuzzy logic controller is proposed. The fuzzy logic controller is used to reduce the flux and torque ripples and it improves performance DTC especially at low speed. A duty ratio control scheme for an inverter-fed induction machine using DTC method is presented in this article. The use of the duty ratio control gives improved steady state torque response, with less torque ripple than the conventional DTC. Fuzzy logic control (FLC) used to implement the duty ratio controller. Total harmonic distortion (THD) calculation of electromagnetic torque, rotor speed and stator current of DTC and DTC with fuzzy has done successfully in this article. With the help of FLC with duty ratio, 8% THD in torque, speed and stator current have minimized compared with DTC (Uddin and Hafeez, 2012). In this paper, switching loses minimization technique through THD minimization. Switching losses are minimized because the transistors are only switched when it is needed to keep torque and flux within their hysteresis bounds, improve efficiency & reduced losses. Direct torque control with the fuzzy logic controller has verified by MATLAB SIMULINK and experimentally.

Rotor Flux-Oriented Control of Induction Motor With Synchronized Sinusoidal PWM for Traction Application

This paper proposes a vector-controlled squirrel cage induction motor drive with synchronized sinusoidal pulse width modulation (PWM) for traction applications. In traction applications, switching loss in insulated-gate bipolar transistors is very important, and hence, a switching frequency of few hundred hertz is used in these devices. A triangular carrier comparison-based synchronized sinusoidal PWM for medium-voltage inverters with low switching frequency (less than 500 Hz) is proposed in this paper. To have very good dynamic behavior of the synchronization scheme, the triangular carrier is generated from the instantaneous voltage references in a phase-locked manner. A synchronous carrier-based overmodulation scheme that ensures linearity between the reference voltage and the fundamental motor terminal voltage is also proposed. An inverse gain-based linearization method is used to match the reference and inverter output voltage fundamental. This overmodulation strategy fails at the zone of high values of modulation index and a reference modification approach is used in that zone. The proposed PWM and overmodulation schemes integrate methods of field weakening and harmonic current estimation available in the literature and propose a consolidated scheme, which ensures good dynamic response with wide speed variation for rotor flux-oriented induction motor drive. The scheme is experimentally verified and the results are presented.

Model Reference Adaptive Controller Based Rotor Resistance Estimation for Vector Controlled Induction Motor Drive Using Artificial Intelligence

For high performance application in industries induction motor with indirect field oriented control is used due to its excellent dynamic behavior. However, it is sensitive to changes in rotor time constant and has to be estimated online. In this paper a scheme based on the reactive power model reference adaptive controller is designed for estimating the rotor time constant. One of the major advantages of the reactive power adaptive controller is that the rotor time constant estimation is not affected due to the change in stator resistance. The estimation requires only the measurement of motor terminal voltage and current. The effectiveness of the TS fuzzy controller as an adaptive mechanism for estimation of rotor resistance during four quadrant operation of motor drive is investigated in Matlab/Simulink environment and is compared with the conventional PI and Mamdani fuzzy controller.

A study of bipolar control action with EMPC for the position control of DC motors

The paper studies the use of bipolar control action with experience mapping based prediction controller (EMPC) for the position control of DC motors. EMPC is based on the human learning mechanism without any need for a detailed mathematical plant model. Experiential learning is used in EMPC to control and adapt to environmental changes introducing robustness. An improved method for the development of experiences to achieve faster settling times is presented. A new concept of control action in EMPC to achieve faster response named ‘bipolar action’ is presented. The advantages of bipolar action are studied in terms of the transient response characteristics and adaptation to changes in system parameters. The performance of EMPC using bipolar action is compared against the use of unipolar action and also against the popular MRAC for position control for changes in active load torque, motor terminal voltage and armature resistance. A new method of correcting the control action by sampling the system response during the initial phase to reduce the overshoots in systems where overshoots are not tolerated is presented. EMPC with bipolar action is practically implemented and the results are provided and compared with the simulation results.

Rotor eccentricity fault compensation by voltage control of brushless DC motor

Rotor eccentricity is one of the common failures that can happen to a motor. In recent years, considerable amount of researches for rotor eccentricity fault diagnosis have been presented. However, no attention is given to the case of ‘eccentricity fault tolerant control’. The necessity of ‘eccentricity fault tolerant control’ is the importance of motor continuous operation during fault in sensitive industries with the best possible performance. Applying conventional control methods during eccentricity fault is not efficient. Since, these methods do not consider eccentricity fault effects such as distortion in flux linkage distribution and motor back-electro-motive force (EMF) waveform, as well as phase inductances changes which may lead to undesirable torque ripples. Hence, a new control strategy for improving motor performance is advantageous. In this study, a control method for brushless direct current (BLDC) motor in presence of static rotor eccentricity is proposed. On-line estimation of phase inductances and phase-to-phase flux linkages during eccentricity is the basis of the proposed control method. In the proposed strategy, the controller adjusts motor terminal voltages considering changes in motor specifications because of eccentricity, without using phase current control loop. Experimental results verify performance of the proposed method in reducing electromagnetic torque pulsations during fault.