Torque Improvement of Spoke-type Permanent Magnet Motor with Auxiliary Stator Using Harmonic Current Control Strategy

The spoke-type permanent magnet motor with auxiliary stator exhibits high torque performance owing to the flux focus effects.To further improve its torque density,this paper proposes a control method by using harmonic current strategy.Based on the theoretical analysis,a 3-D torque look-up table by dq-axis current and electrical angle is established with the aid of the finite element method(FEM).The maximum torque per ampere curve at each rotor position is identified and summarized to adequately indicate the relationship between torque and current amplitude of the motor.Through theoretical derivation,it is concluded that the minimum torque cost curve is the contour line of?Te/?i2,which can be employed to identify the harmonic current for torque density improvement.Compared to traditional strategies,the proposed control strategy can increase torque density of forward and reverse torque by 1.22%and 1.40%,respectively.The experimental results verify the analysis and simulation results,as well as prove the effectiveness of the proposed strategy.

Research on Open-circuit Fault Tolerant Control of Six-phase Permanent Magnet Synchronous Machine Based on Fifth Harmonic Current Injection

This paper proposes a novel control approach for fault-tolerant control of dual three-phase permanent magnet synchronous motor(PMSM) under one-phase open-circuit fault.A modified six-phase static coordinate transformation matrix and an extended rotating coordinate transformation matrix are investigated considering the influence of the fifth harmonic space on fault-tolerant control. These mathematical models are further analyzed in the fundamental space and the fifth harmonic space after the fault and to eliminate the coupling between the d-q axis voltage equation in the fundamental wave space and the d-q axis voltage equation in the fifth harmonic space, a secondary rotation coordinate transformation matrix is proposed. To achieve the purpose of reducing torque ripple, the fault-tolerant control method proposed in this paper not only takes the minimum copper loss as the constraint condition, but also injects the fifth harmonic current. The experimental result of current and torque is used to verify the accuracy of fault-tolerant control.

An Insight into the Second-Harmonic Current Reduction Control Strategies in Two-Stage Converters

Due to the components at twice the fundamental frequency of output voltage in the instantaneous output power of a two-stage single-phase inverter(TSI),the second harmonic current(SHC)is generated in the frontend dc-dc converter(FDC).To reduce the SHC,optimizing the control strategy of the FDC is an effective and costless approach.Fromthe view of visual impedance,this paper conducts an intensive study on the SHC reduction strategies.Origin of the SHC is illustrated first.Then,the equivalent circuit models of the FDC under different control strategies are proposed to analyse the SHC propagation characteristic.The derived model can offer a better insight into how the inductor SHC is affected by the control parameters.According to the derived models,a synthesis of different control strategies is presented and the relevant parameters are listed for control design to achieve better suppression effect.The benefits and limitations of these control strategies are also discussed.Based on the proposed equivalent circuit models,several optimization methods are proposed to enhance the effect.A 1500 VA TSI prototype is built and simulated on MATLAB/Simulink,verifying the effectiveness of the proposed optimization methods.This paper is aimed to provide a guideline for the control design and control optimization of the TSIs.

Recent Developments of Modulation and Control for High-Power Current-Source-Converters Fed Electric Machine Systems

The pulse-width-modulated(PWM)current-source converters(CSCs)fed electric machine systems can be considered as a type of high reliability energy conversion systems,since they work with the long-life DC-link inductor and offer high fault-tolerant capability for short-circuit faults.Besides,they provide motor friendly waveforms and four-quadrant operation ability.Therefore,they are suitable for high-power applications of fans,pumps,compressors and wind power generation.The purpose of this paper is to comprehensively review recent developments of key technologies on modulation and control of high-power(HP)PWM-CSC fed electric machines systems,including reduction of low-order current harmonics,suppression of inductor–capacitor(LC)resonance,mitigation of common-mode voltage(CMV)and control of modular PWM-CSC fed systems.In particular,recent work on the overlapping effects during commutation,LC resonance suppression under fault-tolerant operation and collaboration of modular PMW-CSCs are described.Both theoretical analysis and some results in simulations and experiments are presented.Finally,a brief discussion regarding the future trend of the HP CSC fed electric machines systems is presented.

Distorted Waveform Balancing Using an Artificial Bee Colony (ABC) Based Optimal Control for Mitigating Total Harmonics in Single Phase Inverter

The main objective of this paper is to reduce the total harmonics in a single phase voltage source inverter using Artificial Bee Colony (ABC) optimization technique for critical load applications. Single phase inverter is a non-linear load using power electronic components causing distortions in the load voltage and current wave patterns from the sinusoidal waveforms due to harmonics. The mapping state space model for a full bridge voltage source inverter was developed using output load resistance. An optimal ABC technique has been designed and optimized values are estimated using a full bridge voltage controlled inverter using Proportional Integral Algorithm. The MATLAB/SIMULINK tool and Experimental setup were implemented and their THD values were estimated. Also this ABC scheme is compared with the previous results such as PI Algorithm, Fuzzy logic controller and Neuro-fuzzy controllers. From the simulation and experimental results using ABC algorithm, it is observed that the total harmonics are mitigated considerably compared to previous results with respect to the power quality standards such as IEEE-519 and IEC 61000.

Research on Torque Ripple Under Healthy and Open-Circuit Fault-Tolerant Conditions in a PM Multiphase Machine

In this paper,research into torque ripple production has been undertaken for both the healthy and open-circuit faulttolerant conditions of a five-phase permanent magnet(PM)machine by using the instantaneous power(I-Power)approach.When only the fundamental component of the phase currents is applied to the phase windings,it has been shown that the 9th and 11th harmonics of the back-electromotive force(back-EMF)causes torque ripples in a five-phase PM machine and its frequency is ten times the frequency of the fundamental phase currents.When the combined fundamental and third harmonic components of the phase currents are applied to the phase windings,it has been shown that the 7th and 13th harmonic of the back-electromotive force(back-EMF)causes additional torque ripples in a five-phase PM machine.These torque ripples under fault-tolerant conditions have been analyzed analytically,as well.It has been proven that there are interactions between the fundamental component of current and the third harmonic component of the back-EMF and vice versa.These interactions cause torque ripples.A finite element analysis(FEA)model of the five-phase PM machine has been done to validate the analytical results.

Realization of Unified Power Quality Conditioner for Mitigating All Voltage Collapse Issues

This paper proposes about a powerful control mechanism of UPQC (Unified Power Quality Conditioner) work on voltage source inverter which can effectively compensate source current harmonics and also mitigate all voltage collapse such as dip, swell, voltage unbalances and harmonics. The consolidation of series and parallel active power filters sharing mutual DC bus capacitor forms UPQC. PI (Proportional Integral) controller is mainly used in order to maintain continual DC voltage along with the hysteresis current controller. The parallel and series power filters were designed using 3-phase voltage source inverter. The reference signals for shunt and series active power filters were obtained by Synchronous Reference Frame (SRF) theory and Power Reactive (PQ) theory respectively. By using these theories, reference signals were obtained which was fed to the controllers for generating switching pulses for parallel and series active filters. The UPQC dynamic performance is obtained through testing terms like the compensation of voltage, current harmonics and all voltage distortion associated with 3-phase 3-wire power system which is simulated using MATLAB-Simulink software.