Differential Evolution Technique Of HEPWM For Three-Phase Voltage Source Inverter

This paper presents the execution of Differential Evolution (DE) algorithm in order to understand the principle operation of Harmonic Elimination Pulse-Width Modulation (HEPWM) switching technique. HEPWM utilizing the DE technique is proposed to eliminate low frequency harmonic components of three-phase inverter output voltage. Explanation of DE algorithm execution is given and the best approach of mutation strategy used in DE has been investigated. Switching angles of HEPWM are calculated offline by using the DE technique. Subsequently, the calculated switching angles are used to operate the three-phase voltage source inverter. Computation of DE algorithm and simulation of voltage source inverter using the calculated switching angles are carried out by using Matlab/Simulink software package. Simulation results show the effectiveness of proposed DE technique in eliminating the low order harmonic components of output voltage for three-phase voltage source inverter

Analysis, design and control of grid connected three phase pulse width modulated AC-DC converter

The increasing penetration of line-commutated power diode and thyristor rectifiers into the grid power system is becoming a problem in transmission and distribution lines due the harmonic and reactive currents they inject to the grid system. Therefore, three-phase pulse width modulation (PWM) ac-dc converters are becoming more and more attractive for replacing the line-commutated rectifiers in the utility-interface applications. With a proper control technique, the PWM ac-dc converter is able to reduce the harmonics in the line currents. This leads to the achievement of almost sinusoidal input currents and provides controllable de-link output voltage, unity power factor operation and regeneration capability. These features are not necessarily achieved under non-ideal operating conditions such as unbalanced, distorted and disturbed grid supply. -- This thesis investigates a virtual flux control for reducing the number of sensors in the direct power control (DPC) and the voltage oriented control (VOC) of a three phase PWM ac-dc converter. The use of input ac voltage sensors to measure the grid voltage for synchronization and estimation of input instantaneous active and reactive powers is avoided by applying a virtual flux concept in the new proposed control schemes. The virtual flux control technique is used to extract the grid voltage information from the converter switching states, de output voltage and line currents. -- A virtual flux direct power control (VFDPC) utilizing an improved virtual flux estimator and a newly designed switching look-up table, is proposed in this thesis. The switching look-up table is developed based on the instantaneous power derivative method which relies on the sign and magnitude of the change in instantaneous active and reactive powers. In this way, the switching table is able to choose the best converter voltage vector in order to ensure smooth control of active and reactive powers. -- Furthermore, a new virtual flux oriented control (VFOC) technique is proposed so that the ac-dc converter operates with a fixed switching frequency. The VFOC control structure is developed by using a newly derived mathematical model of the three phase ac-dc converter incorporating the estimated virtual flux components. Subsequently, the proposed VFOC is able to include the decoupling network and feed-forward control components to enhance the converter performance during the grid and load disturbances. -- It has been confirmed through simulation and experiment that the proposed VFDPC and VFOC are able to produce three phase sinusoidal input currents with low total harmonic distortion, near unity power factor and adjustable de-link output voltage under balanced and non-ideal conditions of the input voltage supply

Analysis of natural sampled PWM switching strategy for a cascaded multilevel inverter using double integral fourier method

This paper describes a method to obtain a closed-form solution of the PWM output voltage waveform using a technique known as the double integral Fourier series expansion. A thorough treatment of on the mathematical derivation spectra of output voltage of a cascaded five-level inverter using this approach is given. This is followed by a verification of the results using practical results from a specially built test-rig. In addition, the harmonic spectra obtained from the closed-loop solution are compared with the calculation using the MATLAB time-based simulation

Real-Time Implementation Of D-Q Control For Grid Connected Three Phase Voltage Source Converter

This paper investigates a new approach to develop and implement a virtual flux oriented control (VFOC) for the front-end three phase bidirectional voltage source converter (VSC) by adapting the principle operations of voltage oriented control (VOC) and power estimation used in virtual flux direct power control (VFDPC).The proposed VFOC operates with minimal number of sensors by avoiding the used of ac voltage supply sensors.In addition,the proposed control scheme utilizes the direct and quadrature (d-q) decoupling and feed-forward components to enhance the performance of front-end VSC during load and supply voltage disturbances.The steady-state as well as the dynamic performance of the proposed controller is presented and analyzed by means of the Matlab simulation, and verified through experiment.The ac-dc converter utilizing VFOC is able to produce adjustable dc output voltage,fixed switching frequency,unity power factor and low harmonic distortion of the line current

HEPWM Using Differential Evolution Technique For Three Phase Voltage Source Inverter

This paper presents the implementation of Differential Evolution (DE) algorithm to solve Harmonic Elimination Pulse-Width Modulation (HEPWM) problem. HEPWM is widely used in eliminating the low frequency harmonic of output voltage of the inverter. The DE is a simple and efficient evolutionary algorithm in solving the HEPWM transcendental equation. Operations of DE technique were elaborated and the best approach of mutation strategy has been analyzed. Switching angles of HEPWM were calculated offline using DE technique. Then, the switching angles were applied to three-phase voltage source inverter (VSI). Simulation of DE technique and VSI experiment set up were run in Matlab/Simulink

Independent Control For Dual-PMSM Drives Using Five-Leg Inverter

This paper aims to implement an independent speed control for dual-PMSM drives fed by a single Five-Leg Inverter (FLI). In general, dual-motor drives are designed to reduce size and cost with respect to single motor drives. However, dual-motor drives using a single three-leg inverter has its limitation in the case of operation at different operating conditions and independent speed control requirement. By employing this FLI topology, the dual-motor drives can be used for four-quadrant control, variable speed operation and load disturbance rejection. In other words, it can be operated for different applications. This paper investigates the behaviour of independent speed control for Dual-Permanent Magnet Synchronous Motor drives. The speed and current controllers are implemented in d-q rotor reference frame using Simulink/MATLAB and the switching signals are generated by the built-in function and dSPACE. The overall performance of the drives is presented in terms of speed responses under forward and reverse operation. The three-phase current and quadrature current responses are also included. The experimental results of the drives under investigated study have proven that dual-PMSM can independently controlled by using FLI

An Improved Simplified Rules Fuzzy Logic Speed Controller Method Applied For Induction Motor Drive

Fuzzy Logic Speed Controller (FLSC) has been widely used for motor drive due to its robustness and its non-reliance to real plant parameters. However, it is computationally expensive to be implemented in real-time and prone to the fuzzy rules’ selection error which results in the failure of the drive's system. This paper proposes an improved simplified rules method for Fuzzy Logic Speed Controller (FLSC) based on the significant crisp output calculations to address these issues. A systematic procedure for the fuzzy rules reduction process is first described. Then, a comprehensive evaluation of the activated crisp output data is presented to determine the fuzzy dominant rules. Based on the proposed method, the number of rules was significantly reduced by 72%. The simplified FLSC rule is tested on the Induction Motor (IM) drives system in which the real-time implementation was carried out in the dSPACE DS1103 controller environment. The simulation and experimental results based on the proposed FLSC have proved the workability of the simplified rules without degrading the motor performance