Open-end Winding Induction Motor Research Articles

Modified H‐bridge inverter based fault‐tolerant multilevel topologyfor open‐end winding induction motor drive

This study presents a three-phase modified H-bridge based multilevel inverter(MLI) topology for an open-end winding induction motor drive (OEWIMD). Theoperation of the proposed topology under open-circuit and short-circuit faultconditions of a switch is investigated. Proposed MLI topology is designed withthree three-phase modified H-Bridge inverters connected in a star configurationto feed an OEWIMD. This topology has advantage of delivering a maximum voltageof twice the supply voltage and is replicated as nine levels in the phasewindings of OEWIMD, thereby reducing the total harmonic distortion. Therefore,lower voltage rating sources such as solar cells or fuel cells can be used forthis topology. This topology becomes cost effective since the operating voltagerange required for the devices is less. Controlling methods such as conventionallevel-shifted and multi-reference sinusoidal pulse width modulation techniquescan be applied for this topology. A fault-tolerance strategy is proposed forinverter switch open-circuit and short-circuit faults that adds fault-tolerancecapability to the proposed topology. Simulations were performed usingMATLAB/Simulink and experimental results are presented for both normal operatingand fault-tolerance mode that confirms the inherent fault-tolerance property ofthe proposed MLI topology.

An Active Modulation Scheme to Boost Voltage Utilization of the Dual Converter With a Floating Bridge

This paper proposes a capacitor voltage regulation method for the dual converter with a floating bridge for aerospace applications. This topology has previously been reported, but with a constrained voltage utilization factor due to the need for capacitor voltage regulations. In this paper, the effect of switching states on the voltage variation of capacitor is quantitatively modeled and an enhanced space vector modulation scheme with current feedback is proposed to achieve an active control of the floating capacitor voltages. This proposed method also allows further exploitation and utilization of converter voltage. The relationship between the allowed modulation index of dual converter and load power factor is obtained and expressed using a fitted polynomial equation. The advantages of the proposed method include boosted voltage utilization and superior performance in term of capacitor voltage balance. These advantages have been proven through simulation and experimental results on RL loads as well as with an open-end winding induction motor. The proposed modulation scheme can boost the converter voltage utilization by at least 10% while achieving full four-level operation. More importantly, the higher available voltage allows extending the constant torque region of the motor, the further beginning of field weakening operation could be postponed.

Common-Mode Current Elimination PWM Strategy Along With Current Ripple Reduction for Open-Winding Five-Phase Induction Motor Drive

The three-level dual-inverter connected to five-phase open-end winding induction motor (FPOEWIM) drive with a single dc source results in the flow of common mode current (CMC). The CMC flows through the common dc bus connected to dual-inverter and the motor phase windings. The CMC can be eliminated by using the switching states that can generate zero common mode voltage (CMV). In case of FPOEWIM, these switching states may result in higher current ripple. This paper proposes a decoupled pulsewidth modulation (PWM) technique to reduce the motor phase current ripple by using nearest possible space vector locations (SVLs) with zero as well as non-zero CMV. The use of non-zero CMV states results in CMC. So, the CMC is averaged to zero using sample-averaged common-mode current elimination (SACE) PWM technique in conjunction with decoupled PWM, which is named as DSACE PWM technique. Furthermore, the application of the proposed PWM is also supported using simulation for the closed-loop control scheme, such as DTC. Also, the proposed decoupled and DSACE PWM techniques are verified experimentally and the results are compared with the conventional 144° decoupled PWM technique.

Fault Detection and Identification Scheme for Dual-Inverter Fed OEWIM Drive

Dual-inverter configuration has been attracting increasing attention, especially in motor drives, for its advantages in fault tolerance, multilevel modulation effect, dc voltage utilization, etc. However, its switch fault diagnosis is difficult due to the symmetry of the two sub-inverters. A signal processing approach is proposed in this paper to detect the switch open-circuit fault occurrence and further identify the specific faulty switch, benefiting maintenance and fault-tolerant operation. In this scheme, the faulty phase and the faulty switch pair, consisting of the faulty switch and the switch on its diagonal, are identified using the stator phase currents average values. Following that, the bridge of the faulty phase is forced into a unipolar mode by artificially turning off one switch in the healthy pair continuously. Through properly controlling the duty ratios of the other switches in this bridge, the faulty switch is allowed to be further identified from the faulty pair by analyzing the behavior of the induced current in this phase. This approach is independent of either the speed or the voltage information. The effectiveness is validated through experiments on a sensorless controlled open-end winding induction motor drive.

Enhanced direct torque control and predictive torque control strategies of an open‐End winding induction motor drive to eliminate common‐mode voltage and weighting factors

Direct torque control (DTC) and predictive torque control (PTC) strategies emerged as powerful tools for speed control of variable frequency drives (VFD). The limitations in classical DTC and PTC are: higher ripple in torque, flux, variable switching frequency, and higher common-mode voltage (CMV). High dv/dt and CMV results in shaft voltages, bearing currents, malfunction of power electronic devices and electromagnetic interference (EMI). To eliminate the CMVs and also to reduce the switching frequency, voltage vector selection-based DTC and PTC strategies are introduced to an open-end winding induction motor (OEWIM) drive. Another limitation of classical PTC is cumbersome tuning of weighting factors. To address this limitation, modified cost function-based PTC strategy has been developed to eliminate weighting factors. OEWIM drive operates with dual inverter configuration and the two inverters are operated with equal DC-link voltages; therefore, it delivers three-level output voltage. This article introduces various DTC and PTC strategies to an OEWIM drive to reduce torque, flux ripples, switching frequency, elimination of CMV, and weighting factors. The effectiveness of proposed DTC and PTC strategies is tested by dspace-1104 real-time interface controller and comparing the obtained results with classical DTC and PTC.

Effect of center voltage vectors (CVVs) of three-level space plane on the performance of dual inverter fed open end winding induction motor drive

Dual inverter fed open end winding induction motor (IM) drive offers many advantages over other multilevel inverter fed IM drives. Pulse width modulation (PWM) techniques are employed for the control of output voltage and frequency. Space vector base PWM techniques are popular among all the PWM techniques. A simplified space vector PWM method with simple and small look-up table approach is presented for dual inverter configuration. Moreover the proposed space vector based PWM technique provides freedom in selecting the center voltage vector (CVV) by which different PWM techniques will be derived. The implementation of all these PWM techniques is generalized by using a constant a <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">o</sub> . The derived PWM techniques show superior performance in reducing the zero sequence voltage (ZSV) by maintaining the same quality of output voltage. The performance of all these PWM techniques are evaluated theoretically and verified in real time through dSPACE 1104 control board.

A Simplified Predictive Torque Control Scheme for Open-End Winding Induction Motor Drive

Variable speed induction motor (IM) drives with predictive torque control (PTC) technique is an advancing technology nowadays. The PTC technique is introduced for dual-inverter fed open-end winding IM (OEWIM) configuration owing to its benefits. The conventional PTC requires flux weighting factor assignment because of two different control objectives (torque and flux) in single cost function. This weighting factor selection plays a key role in selecting optimal voltage vector for better torque and flux response. Several analytical and empirical methods are introduced for optimal selection of weighting factor, which demands more computation time. This paper aims to develop modified PTC, eliminating flux weighting factor. The flux control objective is replaced by an equivalent reactive torque control. Thus making two control objectives of the same units and eliminating the requirement of flux weighting factor in cost function. Furthermore, nearest voltage vector selection strategy is introduced to limit the number of prediction voltage vectors in each sampling period. Thus, overall computational burden is reduced achieving minimum torque and flux ripples. The performance of the proposed PTC for multilevel inversion fed OEWIM is evaluated through MATLAB/Simulink simulations and experimental analysis. To highlight its benefits, these results are compared with those of the conventional and recent PTC techniques.

A Load Commutated Multilevel Current Source Inverter Fed Open-End Winding Induction Motor Drive With Regeneration Capability

This paper presents a load commutated silicon controlled rectifier (SCR) based multilevel current source inverter (CSI) fed open-end winding induction motor (IM) drive with regeneration capability. Multilevel current waveform is realized using two isolated load commutated SCR-based CSIs connected in shunt configuration, but operated with a phase shift of 30 $^\circ$ thereby attaining significant reduction in harmonic distortion of the motor current. The multilevel CSI connected to one side of the stator windings supplies real power to the motor. The other end of the stator winding is directly interfaced with a capacitor-fed voltage source inverter (VSI). The control scheme of the VSI facilitates load commutation of the multilevel CSI under all conditions of operation, including regenerative braking. The proposed scheme is experimentally verified on an IM with open-end stator winding, with the help of a digital signal processor TMS320F28335.

Analysis of coupled and decoupled PWM techniques for induction motor drive

Dual inverter fed induction motor drive-in open-end winding gives more advantages than multilevel inverter fed induction motor drives. For better quality of output voltage with low common mode voltage (CMV), in this paper analysis of coupled and decoupled PWM techniques for open end winding induction motor are carried. The analysis is carried in MATLAB/simulink environment for vector controlled open end winding induction motor drive. The performance of drive and PWM techniques are evaluated both in transient, steady state and loaded conditions.

Analysis of coupled and decoupled PWM techniques for induction motor drive

Dual inverter fed induction motor drive-in open-end winding gives more advantages than multilevel inverter fed induction motor drives. For better quality of output voltage with low common mode voltage (CMV), in this paper analysis of coupled and decoupled PWM techniques for open end winding induction motor are carried. The analysis is carried in MATLAB/simulink environment for vector controlled open end winding induction motor drive. The performance of drive and PWM techniques are evaluated both in transient, steady state and loaded conditions.

Investigation on SVM-Backstepping sensorless control of five-phase open-end winding induction motor based on model reference adaptive system and parameter estimation

This paper deals with a new control technique applied to five-phase induction motor under open-end stator winding (FPIM-OESW) topology using the backstepping nonlinear control. The main objective is to improve the dynamics of this kind of machine, which is intended to be used in high power industrial application, where the maintenance is difficult and the fault tolerant is needed to ensure the continuous motor operating mode with minimized number of interruption. This control technique is combined with the Space Vector Pulse Width Modulation (SVPWM) to maintain a fixed switching frequency. In addition, the Model Reference Adaptive System (MRAS) concept is used for the estimation of the load torque, the rotor flux and the rotor speed to overcome the main drawbacks presented with the previous sensorless systems concepts. However, the great sensitivity to the changes of the motor internal parameters and it operating instability problems, especially in low-speed operating region, that causes an estimation error of the rotor speed, is the most disadvantage of the MRAS technique. Therefore, to solve this problem, an estimation method of the motor internal parameters such as the rotor resistance, the stator resistance and the magnetizing inductance, is proposed in this paper. Where, the main aim is to improve furthermore the control performance, to reduce the computational complexity and to minimize the rotor speed estimation error. The obtained simulation results confirm the enhanced performance and the clear efficacy of the proposed control technique under a variety of cases of different operating conditions.

Coupled random PWM technique for dual inverter fed induction motor drive

Dual inverter fed induction motor drives provide more advantages in contrast with other multilevel inverter drives. Coupled PWM techniques provide good standard of output voltage than the decoupled PWM techniques for dual inverter configuration. In this paper analysis of open end winding induction motor by coupled random PWM signals and decoupled SVPWM signals was carried out. Induction motor by random PWM technique generate low acoustic noise and electromagnetic interference to near by systems. The performance evaluation of the drive wss implemented in MATLAB/simulink and the results were presented.

A Novel FLC Based Closed-Loop V/f Control of Five-Level Inverter Fed Open-End Winding Induction Motor Drive

A fuzzy logic based closed-loop V/f control scheme for five-level inverter-fed open-end winding induction motor drive is proposed and experimentally validated in this paper. To the best of the authors’ knowledge, closed-loop V/f control for open-end winding induction motor has not been explored so far. The five-level inversion operation is achieved by feeding one end of the open-end winding induction motor by 3-phase, 3-level cascade inverter and other by 3-phase, 2-level inverter. To achieve the closed-loop V/f speed control, a fuzzy logic based auto tuned controller is designed. The controller is capable of reducing undesired sustained oscillations under different loading conditions. A hardware prototype model of the drive is developed to investigate the performance of the proposed controller for the full range of speed under light and high loading conditions.

Fixed switching frequency predictive control of an asymmetric source dual inverter system with a floating bridge for multilevel operation

This study proposes a modified modulated model predictive control (MMPC) scheme to control an open-end winding induction motor drive using an asymmetric source dual inverter with one floating bridge. The control algorithm uses a modulation algorithm within the cost function optimisation scheme to avoid variable switching frequency. The voltage of the floating capacitor is regulated utilising predefined redundant switching sequences as well as the voltage vector location is identified to improve calculation time. The proposed MMPC scheme enhances the output performance with comparison to the model predictive control scheme. Experimental results are presented to verify theory and simulation results.

Enhanced Predictive Torque Control for Open End Winding Induction Motor Drive Without Weighting Factor Assignment

Nowadays, predictive torque control (PTC) is the most popular control technique in the field of electric drives. This PTC strategy is introduced for open end winding induction motor (OEWIM) drive in view of advantages. The conventional PTC offers a single-cost function where torque and stator flux control objectives are present. Since these control objectives are dissimilar, weighting factor designation to the respective control objective is essential. Weighting factor tuning by an empirical approach leads to a cumbersome control process. To overcome this tuning problem, this paper suggests a single control objective containing stator reference and predicted flux space vectors. This simplified proposed control scheme relieves PTC from weighting factor and facilitates combined torque and flux control. However, to control inverter switching frequency including torque and flux in a single cost function, weighting factors assignment and its proper tuning is indispensable. The proposed scheme is extended by replacing a single-cost function with separate multiobjectives and its optimization is achieved using a simple ranking analysis with limited prediction voltage vectors (VVs). This proposed feature permits PTC independent from weighting factors. Simulation and experimentation are performed on a dual inverter fed OEWIM drive. The achieved results are related with conventional PTC to verify the effectiveness of the proposed PTC.

High-Efficiency Operation of an Open-Ended Winding Induction Motor Using Constant Power Factor Control

A controller is presented for an open-ended winding motor dual-inverter drive (DID), where main and floating inverters are supplied from a dc power source and a floating dc capacitor, respectively. The controller utilizes the efficiency characteristic of induction machines, where high power conversion efficiencies are obtained when operating the machine with a constant fundamental power factor, typically around 0.70–0.75, over a wide load range and under variable frequency. The controller uses the drive's topology to maintain the motor's desired power factor. In essence, the main inverter's output voltage is used to control the floating inverter's dc capacitor voltage to keep the injected fundamental voltages of both inverters at a desired ratio. The floating inverter's voltage is operated with a 90° lead relative to the main inverter and uses a constant maximum amplitude modulation depth to minimize the capacitor's operating voltage. This approach updates the motor's voltage automatically to ensure constant power factor operation and improves the floating capacitor's voltage stability during transient conditions. The inherent voltage-boosting capability of this topology is especially beneficial in extending the constant torque region of the motor and improving performance in the speed range extension region. Simulation and experimental results verify the predicted motor efficiency gains and stability under speed and load transients.

Performance Evaluation of 18-Level Inverter Fed Open-end Winding IM Drive

A novel hybrid 18-level inverter topology for open-end winding induction motor (OWIM) is presented in this paper. In the proposed topology one end of the open-end winding IM is fed by a conventional two-level inverter, while other end is connected to a nine-level cascade H-bridge (CHB) inverter. The combined effect of these two inverters generates 18 levels in the phase voltage of open-end winding IM. The two-level inverter with higher DC link voltage has lower switching frequency and thereby reduces the switching losses. In addition to that, the proposed topology requires less number of components as compared to conventional multilevel inverter (MLI) topologies. An interesting feature of the proposed topology is that, it can operate in nine-level mode by connecting the motor winding in star in case of failure of the two-level inverter. Similarly, if the fault occurs in CHB inverter the proposed inverter can operate in two-level mode. Thus, the reliability of the system is improved. The proposed topology is experimentally verified on 1.5 kW OWIM. The experimental results have proven an excellent steady-state as well as transient-state performance of the proposed inverter in the entire range of linear modulation.

Dual Solar Photovoltaic Fed Three-Phase Open-End Winding Induction Motor Drive for Water Pumping System Application

The distributed maximum power point tracking (DMPPT) technique is employed in most of the photovoltaic (PV) systems to achieve better conversion efficiency. There exist two basic structures to implement DMPPT technique. The first one uses multiple DC–DC converters connected to the individual PV arrays and a DC–AC inverter connected to the load. The DC–DC converters extract maximum power from each PV array independently. Whereas, the other structure avoids the use of the DC–DC converters and the DMPPT technique is implemented using the multiple DC–AC inverters. This may improve the overall efficiency and reduces the losses, cost, and size of the system. Hence, in this article, the aforesaid structure is adopted for PV pumping system which uses two DC–AC inverters connected to an open-end winding induction motor (OEWIM). Apart from the implementation of DMPPT technique, the proposed system is capable of generating four-level inverter output voltage and work under extreme environmental conditions for two PV sources, which could improve the performance of the motor drive system. The detailed design of all the major components used in the proposed system along with the operation and control are presented in this article. In support, the simulation results and the practical verification are presented.

Five-Level Inverter-Fed Space Vector Based Direct Torque Control of Open-End Winding Induction Motor Drive

This work proposes a space vector based direct torque control scheme implemented on an open-end winding type induction motor fed by a five-level inverter. The modulation algorithm uses a 60-degree coordinate system to avoid fractional arithmetic as present in the standard Cartesian coordinate system, which reduces the arithmetic calculation complexity. Making use of the natural fractal structure of a hexagonal space vector diagram of the multilevel inverter, this scheme uses a fractal-based algorithm for sector identification and switching vector generation. In this scheme, three-phase signals to the space vector modulator are generated based on a torque-flux error by means of transformation logic. Two three-level inverters are fed from both open ends of an induction motor for realizing a five-level inverter. The scheme includes implementation of different levels of inverter-fed direct torque control drive. The control scheme is implemented on a laboratory prototype 2hp induction motor through a TMS320F240 DSP processor based dSPACE DS-1104 controller. The inverter gating signals are generated by using a Virtex-II FPGA board. The hardware results of different direct torque control configurations are presented for validating the algorithm and all the measurements are done under closed-loop operation.

Sample-Averaged Zero-Sequence Current Elimination PWM Technique for Five-Phase Induction Motor With Opened Stator Windings

The five-phase dual-inverter connected to the five-phase open-end winding induction motor (FPOEWIM) with a single dc source could result in the flow of common-mode current (CMC) through the common dc bus and motor phase windings. In addition, the FPOEWIM drive contains third-harmonic content which do not contribute for torque generation in a distributed wound motor. So, to nullify the CMC as well as the third-harmonic content the sample-averaged zero-sequence current elimination (SAZE) pulsewidth modulation (PWM) technique is proposed in this paper. Wherein, the concept of alternative clamping of the inverters is used with the generation of virtual vector to eliminate third-harmonic content and the effective time region is moved to eliminate the CMC in average sense. The detailed analysis of the proposed SAZE PWM technique is presented along with the simulation results and experimental verification.