Implementation Of A New Fast Direct Torque Control Algorithm For Induction Motor Drive

TM4, the industrial partner, is a leading manufacturer and supplier of traction motors and drives for electric vehicle industry in Canada. As a drive manufacturer, they always aim to provide solution which is energy efficient with small footprint. In order to achieve this, they always look for alternative software and hardware solutions. Software modifications, which may improve the system performance in comparison to their existing drive control strategy without increasing the size of the system, are always sought after for continuous improvement of their system. In this regards, the internship is relevant to them for exploring alternative control strategies.

The impact of the proposed sequences has been simulated for 0.4 modulation index with a 0.5 lagging power factor load (power factor angle 60°). The simulation setup consists of the following software: 1) MATLAB/Simulink – used to implement the modulation strategies and switching sequences, and 2) PSIM – used to simulate the T-NPC inverter running with an R-L load and to provide conduction and switching losses of each switch. The inverter switching pulses were generated within Simulink and were fed to PSIM through sim-coupler module which provides a link between PSIM and simulink for the purpose of co-simulation [29].

Using Field Oriented Control, current control is largely unaffected by speed of rotation of the motor[6].In the scheme of filed oriented control motor currents and voltages obtained from the motor are transformed into d-q reference frame. Measured currents from three stator phases these currents which are now in the stator reference frame are converted into two phase using Clarke transformations which are further converted into the corresponding rotor reference frame using Park transformation. The resultant current obtained is dc which is easier for the PI controllers to operate.

Implement various strategies for the overall RPC scheme and perform technical comparison of these different technical options. This includes a special focus on the switching of reactive power elements for following aspects:

In this control method, the error voltage is integrated twice and to generate the reference signal for current tracking, this signal referred to as the nonlinear carrier signal. In the current shaping, instead of the sensed switch current for comparison, the sensed current is integrated to obtain an average value before being compared with the nonlinear carrier signal. This approach reduces the input current distortion and the noise immunity. Its physical realization is more complicated than the OCC control

In the grid new renewable resources are added to extract more power. This adds more power quality issues to grid connection. A Power quality problem is an occurrence manifested as a nonstandard voltage, current or frequency that results in a failure or a mis-operation of end user equipment. This paper investigates the use of a static synchronous compensator (STATCOM) is connected at a point of common coupling with Battery Energy Storage System(BESS)to overcome of a power quality issues of a wind farm equipped with variable speed wind turbines driving Double – Fed Induction Generators (DFIG). A physical control scheme, including four control loops: ac voltage, dc voltage, ac active current and ac reactive current controllers, is pre-specified for the STATCOM. A synthetic algorithm is proposed to embed these physical control loops in the output feedback path. The simulation results demonstrated that under various system disturbances, the proposed mode decoupling STATCOM is effective in regulating IG terminal voltage.

Instructor’s Manual to accompany Electric Machinery Fundamentals, Fourth Edition Copyright  2004 McGraw-Hill, Inc. All rights reserved. Printed in the United States of America. No part of this book may be used or reproduced in any manner whatsoever without written permission, with the following exception: homework solutions may be copied for classroom use. ISBN: ???

A few recent papers [53]-[56] have demonstrated a virtual synchronous machine (VSM) concept, particularly for microgrid applications and usually for distributed generators utilizing the same ac-dc-ac conversion stages. The same concept applied on flywheel based energy storage is discussed in [57]. Given the similarities existed in the MEA power grid and motor controlled thermal storage, it is deemed feasible to implement the VSM concept in this research. A high-level description is shown in Fig. 3. For a synchronous machine in the rotating reference frame, the d-q voltage and current relationship is shown in (1a-b), where vg is the grid voltage, R is the stator resistance, M is the magnetizing, and Ld = Lq = L is assumed. On the other hand, the active front end (i.e., the hex-bridge converter connected to the gird) follows (2a-b) in d-q reference frame at ωc rotating speed, where Rg and Lg are grid tied resistance and inductance, and vc is the output voltage at the converter controlled by modulation index from the dc voltage bus []. The analogy between (1a-b) and (2a-b) is straightforward. By equating the first three terms and varying the modulation indices, md and mq, the active front end mimics the VSM proposed in [ZhongQC]. The purpose of the ac motor-tied inverter (i.e., the left hex-bridge converter in Fig. 3) is to main a constant 270 V dc bus by adjusting the motor speed and torque using conventional vector controls. Given the limited

For the systems where high switching efficiency is needed, it is required and desirable to keep switching frequency much lower. In this state,

In recent years, Permanent Magnet Synchronous Motor (PMSM) has significantly attracted the attention of researchers due to its simplicity of design, ability of operation at wide range speeds, high efficiency and high power/torque density. Hence it has been increasingly used not only in several industrial sectors but also in household appliance and electrical vehicle applications [1-3], [10]. However, a conventional PMSM control needs a sensor to measure the rotor position and rotor speed for ensuring the precision Field Oriented Control (FOC) and speed control, but such sensor presents some disadvantages such as drive cost, machine size, reliability and noise immunity.

This paper investigates adjustable speed induction motor drive using 2-level and 3-level PWM.The result obtained is verified using Matlab simulation.This result compares the hamonic contect in between 2-level and 3-level by FFT analysis tool.To analyse the resulta a carrier based pwm was taken using 2- level and 3- level topology and a threephase bridge convetor with internally generated capability SPWM/SVPWM was intrduced. Carrier freqency18*60Hz, modulation index 0.9, output voltage freqency 60 Hz and ouput voltage phase 0 degre Was fixed. So corresponing to above values,the motor speed was 1800 rpm. Or 188.5 radian/sec, hence torque is 11.87Nm. A two pole squirrel cage motor was taken subjected to 400V dc source with modulation index0.9 prduces 220v rms.when motor starts, at 0.5s it reaches its steady speed 181 radian/sec or 1728 rpm. Now by discretizing the FFT tool displays the frequency spectrum of voltage and current waveforms. These signals are stored in workspace in the ASM structure with time variable generated by the Scope block. As my model is discretized, the signal saved in this structure is sampled at a fixed step and consequently satisfies the FFT tool requirements.It was observed that value of total harmonic distortion(THD) was 65.77 percent in 2-level and 35.11 percent in 3- level for SPWM invertor and 56.77 percent for SVPWM invertor.

DBR followed by a filter and an isolated zeta converter. The filter is designed to avoid any switching ripple in the DBR and thesupply system. An isolated zeta converter is designed to operate in DCM to act as an inherent power factor corrector. This combinationof DBR and PFC converter is used to feed a BLDC motor drive via a three-phase VSI as shown in Fig. 1. The dc link voltage of the VSI is controlled by varying the duty ratio of the PWM pulses of PFC converter switch. However, VSI is operated in a low frequency switching to achieve an electronic commutation of BLDC motor for reduced switching losses. A single voltage sensor is used at the front-end converter for the control of dc link voltage for speed control of BLDC motor. The proposed drive is designed and its performance is validated on a developed prototype for improved power quality at ac mains for a wide range of speed control and supply voltage variations.

This paper is organized as follows: Section II describes the three phase BLDC motor and mathematical modeling of BLDC. Section III describes the four quadrant operation of the three phase BLDC motor and its features. The controller PI and its features are explained in Section IV. In section V, the simulation results are presented. Section VI concludes the proposed work.

ABSTRACT: Power flow control in a long transmission line plays a vital role in electrical power system. This paper uses the shunt connected STATCOM for the control of voltage and power flow. The proposed device is used in different locations such as sending end, middle and receiving end of the transmission line. The PWM control is used to generate the firing pulses of the controller circuit. Simulation modeling of the system is carried out using MATLAB/SIMULINK. Based on a voltage-source converter, the STATCOM regulates system voltage by absorbing or generating reactive power. This paper deals with a cascaded multilevel converter model, which is a 48-pulse (three levels) GTO converter. The simulation studies are carried for sending end, middle and receiving end of the transmission line. The objective is to define the reactive power generated and voltage control at different locations (at sending end, middle, receiving end) of transmission line using STATCOM. KEYWORDS: FACTS device, STATCOM, SVC, PWM, MATLAB /Simulink.

2Control & Mechatronics Engineering, Faculty of Electrical Engineering, Universiti Teknologi Malaysia, 81310 Skudai Johor Bahru, Malaysia