Quadrature Axis Research Articles

Design of a Large Capacity Line-Start Permanent Magnet Synchronous Motor Equipped With Hybrid Salient Rotor

This article presents a successful design of a three-phase large capacity line-start permanent magnet synchro nous motor (LSPMSM) developed for industrial applications. A hybrid rotor containing both slotted solid steels and cage bars is included in the designed LSPMSM to enhance the motor starting and synchronizing abilities. A salient rotor periphery making air-gap length, which maximizes at the quadrature axis and minimizes at the direct axis, is employed to reduce the harmonics of air-gap flux density and motor losses. The implementation of a genetic algorithm coupled with a neural network optimizes the rotor-periphery saliency ratio and other crucial dimensions for further performance improvement. Finite-element analyses highlight the advantages of the designed LSPMSM by comparing its performance indexes with those of a conventional cage-rotor LSPMSM. The effectiveness of the designed motor is validated by a series of prototype tests.

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.

Pole Reduction Concept for Control of Synchronous Reluctance Motor-Based Solar Photovoltaic Water Pumping System for Improved Performance

This article deals with an improved control for synchronous reluctance motor (SyRM)-based photovoltaic (PV) water pumping system, eliminating the speed controller of position sensorless field-oriented control (FOC) of SyRM. The solar water pump drive involves two stages of power conversion. The reference quadrature axis current of FOC is estimated from available PV array power that is being continuously tracked for maximum power point. This eliminates the requirement of an additional speed controller. This improves the transient behavior of overall control under dynamic conditions such as varying solar radiation. A pole is eliminated from overall characteristic equation of open-loop dc link voltage control transfer function. As a result, a single proportional integrator controller satisfactorily controls the whole pumping system. The system is much easier to tune, and by default, immune to aging and variation in pump's constant. This improves fidelity and reduces the overall cost of the system. Performance of this system is validated through a developed laboratory prototype of solar PV array-fed SyRM drive for water pumping. The overall system performance is examined under different environmental conditions.

Equivalent 3-Level PWM: An Improved Technique to Reduce Torque Ripple in DI-WRIM Analyzed as DI-OWIM

In the supersynchronous mode of double-inverter-fed wound rotor induction machine (DI-WRIM) drive, torque ripple is dependent on the sum of the quadrature ( $q$ ) axis stator and rotor flux ripples (termed as overall flux ripple). Therefore, in the existing method, the torque ripple is reduced by merely changing the slope of one of the flux ripples such that their sum is reduced. However, the torque ripple can be further reduced, as the overall flux ripple in DI-WRIM resembles the $q$ -axis stator flux ripple of a double-inverter-fed open-end winding induction machine which is generally analyzed as a three-level neutral-point-clamped inverter fed squirrel cage induction machine (SQIM) (3L-SQIM) drive. Thus, in this article, the stator and rotor voltage source inverters are switched together and the resemblance is explored to develop stator–rotor pulsewidth modulation (PWM) combinations, such that the overall flux ripple is equivalent to the $q$ -axis flux ripple of 3L-SQIM. The effect of phase shift between the stator and rotor voltage vectors on torque ripple is analyzed and a hybrid PWM combination is also proposed to minimize the same. The reduction in torque ripple, with the proposed combinations, is validated in terms of the estimated instantaneous and RMS torque ripples. The simulation and experimental results further validate this reduction.

Optimization of vector control torque ripple of permanent magnet synchronous motor based on internal model principle

Due to the dead zone effect caused by the non-ideal device of inverter, the currents of the quadrature and straight axis in the synchronous rotation coordinate of permanent magnet synchronous motor (PMSM) contain a large number of harmonic components, resulting in violent torque harmonics. Based on the field weakening control in single current regulator of interior permanent magnet synchronous motor (IPMSM), this paper gives an analysis of the reason for speed fluctuation, and a novel current compensation control strategy based on internal model control is proposed. By this means, the influence of harmonic currents on electromagnetic torque can be reduced meanwhile the advantage of single current regulator in filed weakening control is fully exploited. The feasibility and effectiveness of the proposed scheme are evaluated by Simulation analyses and experimental results.

Performance Investigation of Quasi Z Source Inverter (QZSI) Fed Induction Motor (IM) Drive System with bGWO-RDF Technique

In this dissertation, a hybrid strategy is intended for performance investigation of Quasi Z Source Inverter (QZSI) fed Induction motor (IM) drive system. The hybrid strategy is the fusion of both the binary version of grey wolf optimization (bGWO) and random decision forest (RDF) and commonly called as bGWO-RDF technique. The main contribution of the dissertation is to control the QZSI for enhancing the stability and the performance of IM drive system using the proposed hybrid strategy. The input of the proposed strategy is the speed and three phase current of IM. With the help of input parameters like actual speed and reference speed of IM, the PI controller gain parameters are optimized using bGWO technique. In order to train the RDF, the PI controller output like reference quadrature axis current and actual quadrature axis current is chosen. By utilizing the RDF, the reference three phase current is generated. By utilizing the actual and reference three phase current, the control pulses are generated at the final stage. Finally, the proposed technique is executed in the MATLAB/Simulink working platform. The effectiveness of the proposed is compared with various existing techniques such as ANN, PSO, PSO-SVM and GSA-SVM. The effectiveness of the proposed and other existing techniques is analyzed in terms of ripples and harmonics reduction, rise time, settling time and steady state error. Furthermore, the statistical analysis is also performed and compared with other existing techniques. The comparison result reveals that the total harmonic distortion (THD) is decreased and the oscillation period of the stator current, torque and speed are eliminated.

Sliding Framework for Inverter-Based Microgrid Control

In this letter, a phase reformulation-based sliding framework is proposed for microgrid to adequately decouple control interacts cross the quadrature axes. This is implemented by formulating another virtual coordinate that rotates with the synchronism frequency, while the original coordinate rotates with the reference frequency. The deviation during transients between coordinates is thus to be eventually mitigated by the intersected controller. The case study in PSCAD/EMTDC shows that, with the sliding framework, frequency and voltage fluctuations can be dramatically reduced.

Field-Oriented Control of a Three-Phase Wireless Power Transfer System Transmitter

This paper presents a method of designing a three-phase wireless power transfer (WPT) transmitter analogous to the stator windings of a three-phase, two-pole electrical machine. A method of deriving the required transmitter coil currents based on lateral receiver misalignment is presented, wherein the transmitter currents are decomposed into direct and quadrature axis components. This decomposition simplifies the derivation of the transmitter currents required to minimize copper losses for a wide range of receiver misalignment by reorienting the transmitter magnetic field toward the receiver. Based on the required transmitter current, the required series compensation capacitors and transmitter voltage sources needed for unity power factor operation are calculated. Simulation results are shown for a 3.3-kW system utilizing a receiver-side voltage-doubling rectifier and 300-V battery. Finally, experimental results on a 1-kW prototype are shown, where a coil efficiency of 95.17% at perfect receiver alignment and 90.52% at 20-cm lateral misalignment was measured.

A Modified LUO Converter for Hybrid Energy System FED Grid Tied Inverter

A novel topology of a hybrid grid connected topology based on photo voltaic system and permanent magnet synchronous generator is proposed in this paper. In this grid connected inverter topology the source are connected to the grid with the help of multi input modified LUO converter followed by a single phase three level inverter. Thus compared to the conventional schemes the proposed topology is modeled with the help of reference frames includes direct axis and quadrature axis elements. The modified LUO converter inherits the advantages compared to other DC-DC to converter topologies. The fuzzy logic based MPPT algorithm shows excellent performance under various testing conditions. The PWM generators are used to trigger the inverter and LUO converter. Steady state and transient response of the controllers are discussed and implement the excellent operation of the hybrid energy system. The grid current synchronization is achieved by using PI controller also it will reduce the THD and satisfies the IEEE harmonics standard.

A new adaptive control method for induction motor (IM) drive using IMFO-RBFNN strategy with random pulse width modulation

This paper proposes an optimal control of Induction Motor (IM) drives using a new optimization technique. The optimization technique is the joined execution of both the Improved Moth flame Optimization (IMFO) algorithm and Radial Basis Function Neural Network (RBFNN). The main objective of the prop osed strategy is to enhance the control performance of the IM while reducing the Total Harmonic Distortion (THD), eliminating the oscillation period of the stator current, torque, and speed. Here, the IMFO technique is optimized the gain parameters of the PI controller based on the IM speed variation and generates the reference quadrature axis current. By using the RBFNN, the reference three-phase current for accurate control pulses of the voltage source inverter (VSI) is predicted. The RBFNN is trained by the input motor actual quadrature axis current and the reference quadrature axis current with the corresponding target reference three-phase current. Furthermore, the proposed method control signals are connected with random pulse width modulation (RPWM) scheme and appropriate pulses are generated and applied to the inverter. With the proposed strategy, the control pulses of VSI are optimized and the proposed system offers a reliable solution. The proposed methodology is implemented in MATLAB/Simulink working platform. The performance of the IM drive is assessed by utilizing the comparative analysis with the existing techniques. The result obtained using the proposed optimization strategy showed that; it can provide the optimal control of IM drive. Also, the proposed strategy is effective in minimize the acoustic noise, torque ripple, eliminate the oscillation period with less computation, and reduces the complexity of the algorithm.

Squeezing-enhanced Raman spectroscopy

The sensitivity of classical Raman spectroscopy methods, such as coherent anti-stokes Raman spectroscopy (CARS) or stimulated Raman spectroscopy (SRS), is ultimately limited by shot-noise from the stimulating fields. We present the complete theoretical analysis of a squeezing-enhanced version of Raman spectroscopy that overcomes the shot-noise limit of sensitivity with enhancement of the Raman signal and inherent background suppression, while remaining fully compatible with standard Raman spectroscopy methods. By incorporating the Raman sample between two phase-sensitive parametric amplifiers that squeeze the light along orthogonal quadrature axes, the typical intensity measurement of the Raman response is converted into a quantum-limited, super-sensitive estimation of phase. The resonant Raman response in the sample induces a phase shift to signal-idler frequency-pairs within the fingerprint spectrum of the molecule, resulting in amplification of the resonant Raman signal by the squeezing factor of the parametric amplifiers, whereas the non-resonant background is annihilated by destructive interference. Seeding the interferometer with classical coherent light stimulates the Raman signal further without increasing the background, effectively forming squeezing-enhanced versions of CARS and SRS, where the quantum enhancement is achieved on top of the classical stimulation.

Sensorless PMSM Drive Implementation by Introduction of Maximum Efficiency Characteristics in Reference Current Generation

This paper presents the efficiency improvement in a speed closed-loop controlled permanent magnet synchronous machine (PMSM) sensorless drive. The drive efficiency can be improved by minimizing the inverter and the PMSM losses. These can be influenced by proper selection of DC-bus voltage and switching frequency of the inverter. The direct (d-) and quadrature (q-) axis current references generation methods, discussed in this paper, further improve the efficiency of the drive. Besides zero d-axis current reference control, the maximum torque per ampere (MTPA) characteristic is normally applied to generate the d- and q-axis current references in vector controlled PMSM drives. It assures control with maximum torque per unit of current but cannot assure maximum efficiency. In order to improve efficiency of the PMSM drive, this paper proposes the generation of d- and q-axis current references based on maximum efficiency (ME) characteristic. In the case study, the MTPA and ME characteristics are theoretically evaluated and determined experimentally by measurements on discussed PMSM drive. The obtained characteristics are applied for the d- and q-axis current references generation in the speed closed-loop vector controlled PMSM drive. The measured drive efficiency clearly shows that the use of ME characteristic instead of MTPA characteristic or zero d-axis current in the current references generation improves the efficiency of PMSM drive realizations with position sensor and without it—sensorless control.

Dual Antiovervoltage Control Scheme for Electrolytic Capacitorless IPMSM Drives With Coefficient Autoregulation

Electrolytic capacitorless vector-controlled interior permanent-magnet synchronous motor (IPMSM) drives have many advantages, such as higher reliability, longer lifetime, and lower cost. However, the dc-link may suffer from the overvoltage during motor transient process due to the use of slim film capacitors in the diode rectifier front end. The conventional antiovervoltage method by controlling the quadrature axis current will lead to energy control error, which causes large dc-link voltage control error. In this paper, a novel antiovervoltage control scheme with coefficient autoregulation is proposed based on the concept of system loss. A dual antiovervoltage controller is designed to enhance the voltage control performance by controlling both the direct and quadrature axis currents to achieve more effective active braking. The coefficients of the dc-link voltage controller are autoregulated to maintain the enough stability margin during the regenerative braking. By using the proposed method, the dc-link overvoltage phenomenon can be avoided while guaranteeing the maximum copper loss during the braking process. The proposed algorithm is ultimately verified on an electrolytic capacitorless IPMSM drive.

Rotor Resistance Estimation for Induction Machines Using Carrier Signal Injection With Minimized Torque Ripple

This paper presents a technique for estimating the rotor resistance of an induction machine over the machine's entire speed and torque range. This technique is based on injecting a relatively low-frequency carrier signal into the reference of the rotor flux linkage magnitude and extracting the induction machine's response to the carrier signal, which is then used in a model reference adaptive system. This paper also presents a technique to minimize the torque ripple generated by the carrier signal. This technique utilizes the rotor flux linkage reference in conjunction with a proportional-integral-resonant feedback plus feedforward control to generate references for the direct and quadrature axis stator currents. This paper also improves tracking of the torque and rotor flux linkage in direct field-oriented control of the induction machine through employing electromotive force and resistive compensation methods for tracking q-axis and d-axis reference stator currents, respectively. Simulation and experimental results demonstrate the effectiveness of the technique over the entire operating range.

A hybrid MWOAL approach for fast and efficient maximum power point tracking in wind energy conversion systems

This paper proposes an efficient hybrid approach for the fast and efficient MPPT in WECS. The system consists of an MPPT based control of IPMSG consisting of a hybrid Meta-heuristic algorithm. The hybrid Meta-heuristic algorithm presented in the proposed approach is the joined execution of both WOA and the ALO algorithm named as MWOAL. In the proposed approach, the WOA is considered to resolve the optimal gain parameters of the PI controller with a minimum error objective function based on the variation of direct and quadrature current parameters. Here, the searching behavior of the whales is modified by using the efficient ALO algorithm is known as modified WOAL MWOAL. The setpoint direct axis and the quadrature axis current parameters of the WECS are determined using the MPPT technique and the loss minimization approach based on the generator speed variation. Hence, the proposed scheme has improved the efficiency of the WECS. At that point, the performance of the proposed adaptive MPPT control of WECS is executed in the MATLAB/Simulink working platform and the execution is assessed using the existing techniques.

Non-Linear Control for Variable Resistive Bridge Type Fault Current Limiter in AC-DC Systems

This paper proposes a non-linear control-based variable resistive bridge type fault current limiter (VR-BFCL) as a prospective solution to ease the effect of disturbances on voltage source converter-based high voltage DC (VSC-HVDC) systems. A non-linear controller for VR-BFCL has been developed to insert a variable optimum resistance during the inception of system disturbances in order to limit the fault current. The non-linear controller takes the amount of DC link voltage deviation as its input and provides variable duty to generate a variable effective resistance during faults. The VSC-HVDC system’s real and reactive power controllers have been developed based on a current control loop where direct axis and quadrature axis currents are used to control the active and reactive power, respectively. The efficacy of the proposed non-linear control-based VR-BFCL solution has been proved with balanced as well as unbalanced faults. The results confirm that the oscillations in active power and DC link voltage have been significantly reduced by limiting the fault current through the insertion of an optimum effective resistance with the proposed control technique. The real time digital simulator (RTDS) has been used to implement the proposed approach. The performance of the proposed non-linear control based VR-BFCL is compared with that of traditional fixed duty control.

Explaining the d-q Magnetic Couplings Theoretically in Saturated Smooth Air-Gap AC Machines

The current paper discusses the theoretically detailed physical analysis of the effects of main flux saturation in smooth air gap AC machines. For that purpose, three sections are presented. The first one deals for presenting equivalence saturation-air gap. The second presents the equivalence of inductances between saturation induction machines and a dismounted salient pole synchronous machine. The method analyzes the leakage inductances that properly represent the corresponding leakage fluxes. The third section treats the physical interpretation of the cross-saturation. It is possible to show that the equations and physical picture in a saturated smooth-air-gap machine are similar to the equations and physical picture in a non-saturated salient-pole machine, where mutual coupling exists between the direct and quadrature axes and the self-inductances are also different on the non-salient part of the machine due to the variation of the reluctance with the rotor angle.

Research on Vector Control Strategy of Surface-mounted Permanent Magnet Synchronous Machine Drive System with High-Resistance Connection

High-resistance connection (HRC) is a common electrical fault for the electric machine drive system. This fault can lead to the increased power loss and heat, thus possibly causing the damage of the electric machine drive system due to the excessive temperature. Hence, this paper first proposes a vector control strategy of the surface-mounted permanent magnet synchronous machine (PMSM) drive system with the HRC fault to minimize the copper loss. The mathematical model of the PMSM with the HRC is presented in abc stationary frame. The function relationship between the copper loss and the direct axis current, quadrature axis current, stator resistance, and the additional resistance due to the HRC is established and analyzed. The expression of the direct axis current, which minimizes the copper loss, is deduced under the condition of the HRC in one phase and two phases. Consequently, the proposed vector control strategy for the surface-mounted PMSM driving system is achieved. Both the simulation and experimental results show that the proposed method not only preserves the performance of the conventional vector control method, but also can effectively reduce the copper loss, thus protecting the PMSM from the damage due to the increased temperature possibly caused by the HRC fault.

A Modified Direct-Quadrature Axis Model for Characterization of Air-gap Mixed Eccentricity Faults in Three-Phase Induction Motor

Advanced signal processing techniques and high-speed analog to digital converters enabled on-line detection of internal faults of induction motor even at inception. Reliable and accurate identification of fault signatures in practical situations is always a challenge due to load oscillations, supply harmonics or the presence of multiple faults. Hence model-based analyses are essential for diagnostic studies of faults in machines. This paper proposes a modified direct and quadrature (d-q) axis based approach for modeling a three-phase squirrel cage induction motor with air-gap mixed eccentricity faults. In the proposed model, air-gap length- and thus magnetizing reactance- are modeled as a rotor position-dependent function, to represent various variable air-gap fault conditions. Stator current spectrum is used as the diagnostic signal for detection of the presence of these faults. This simple approach of modeling is computationally less intensive compared to alternative approaches such as multiple coupled circuit modeling and finite element approach. Characteristic signatures of mixed eccentricity fault obtained by simulation studies were also validated in the motor current spectrum obtained through experimentation on a motor with prefabricated eccentricity.

Study on Magnetic Flux Weakening Control Strategy of Interior Permanent Magnet Synchronous Motor

When the maximum ratio of torque to current strategy is used for IPMSM flux weakening speed regulation, it is needed to solve nonlinear High-Order equations determining the direct and quadrature axis current given value. Facing this problem, the paper used the curve fitting and obtained the given current, improved the control accuracy of the system. At the same time, in the weak magnetic high speed zone, proposed a new over-modulation control algorithm, which through the optimization of voltage vector and phase, achieved a natural transition of different modulation region, increased the output voltage of the inverter, and enhanced the stator voltage and output torque when motor runs at a certain speed given value, expanded steady weak magnetic region of IPMSM when the load torque is certain.