VLSI Design

This book provides some recent advances in design nanometer VLSI chips. The selected topics try to present some open problems and challenges with important topics ranging from design tools, new post-silicon devices, GPU-based parallel computing, emerging 3D integration, and antenna design. The book consists of two parts, with chapters such as: VLSI design for multi-sensor smart systems on a chip, Three-dimensional integrated circuits design for thousand-core processors, Parallel symbolic analysis of large analog circuits on GPU platforms, Algorithms for CAD tools VLSI design, A multilevel memetic algorithm for large SAT-encoded problems, etc

Implementation of a Digital Signal Processor (DSP) Based Space Vector Control of AC Induction Motor Drives

The inverters transfer energy from a DC source to a controlled process in the form of pulse trains, using semiconductor switches which are turned on and off at fast repetition rates. This thesis explains in depth how these pulse trains synthesize sine waves. AC waveform generation techniques such as the square wave and Pulse Width Modulation (PWM) are compared in terms of their harmonic elimination capability and fundamental gain control. Various PWM techniques such as bipolar switching, unipolar switching, selective harmonic elimination switching and Space Vector PWM (SVPWM) switching are analyzed and compared in terms of their ability to control harmonic distortion (THD), minimize switching losses, control fundamental gain and maximize DC bus utilization capacity. The selective harmonic elimination technique is covered in depth including a technique that utilizes a neural network controller to remove a selected set of harmonics. This thesis focuses on Space Vector PWM (SVPWM) technique since it has many advantages over other conventional methods such as sine wave PWM. Thus, the SVPWM theory and experimental analysis is presented in depth. The SVPWM technique was realized using the state-of-the- art power electronics hardware and Digital Signal Processing (DSP) software. The experimental procedure and harmonics analysis of the DSP based SVPWM output waveforms and inverter output voltages and currents are presented. The experiments were carried out using power electronics development modules such as the Texas Instrument’s TMS320LF2407 DSK (eZdsp), Digital Motor Controller (DMC1500), and the VisSim™/TI C2000 Rapid Prototyper software package and a three-phase AC induction motor. The VisSim™/TI C2000 Rapid Prototyper was extensively used to model an AC induction motor control sub system that generates real time SVPWM waveforms to control a three-phase induction motor. The AC induction motor control sub-system was implemented using the principle of constant Volts/Hertz (V/Hz) profile. S\u27 averal measurements and observations of the phase-voltages, line-voltages and phase currents were made to observe the quality of the power produced using the SVPWM technique. The SVPWM waveforms were simulated using MATi_AB™ software and the VisSim™/TI C2000 Rapid Protctyper software. These simulated SVPWM waveforms were compared with the DSP generated SVPWM waveforms and the inverter output. The completed project will give the user the ability to use the VisSim™/TI C2000 Rapid Prototyper software to generate SVPWM waveform and power the DSP controller (eZdsp), interface the DMC1500 (inverter) with the eZdsp and control a three-phase induction motor. An extension of the conventional three-phase SVPWM to higher order phase systems is reviewed. An overview of the principle of sensorless variable speed three-phase AC motor drives with closed-loop speed control is included

Sliding Mode Control

The main objective of this monograph is to present a broad range of well worked out, recent application studies as well as theoretical contributions in the field of sliding mode control system analysis and design. The contributions presented here include new theoretical developments as well as successful applications of variable structure controllers primarily in the field of power electronics, electric drives and motion steering systems. They enrich the current state of the art, and motivate and encourage new ideas and solutions in the sliding mode control area

Efficiency Optimised Control of Interior Permanent Magnet Machine Drives in Electric Vehicle Applications

The thesis focuses on the losses minimisation of an interior permanent magnet synchronous machine (IPMSM) drive in electric vehicle applications. As drive losses are a combination of the IPMSM losses and the inverter losses, this thesis is mainly divided into two parts: the first part deals with minimising the copper and iron losses of the IPMSM with due account of machine parameters variations and the voltage drop across the stator winding resistance. A new losses minimisation algorithm (LMA) which considers these issues is presented in this research. A comprehensive off-line simulation study based on this LMA is performed in order to evaluate the effect of the parameters variations, resistive voltage drop and iron losses on the IPMSM optimal efficiency operation. It is shown that the parameters variations and resistive voltage drop should be included in the losses minimisation to achieve IPMSM optimal efficiency operation. On the other hand, the minimum losses operation points are not significantly affected by the utilised IPMSM iron losses. The proposed LMA is implemented with non-linear look-up tables (LUTs) using the current commands developed for both constant torque and field weakening operations. Good matching between the simulation and experimental results has been achieved. Reducing the inverter switching losses is the aim of the second part of this PhD research in addition to decrease the common mode voltage (CMV) which may lead to undesirable motor bearing current and electromagnetic interference. A comparative study between up-to-date PWM techniques for CMV reduction with the conventional space vector PWM (SVPWM technique) through simulation studies are presented. Due to its advantages on reducing both the switching losses and CMV of the inverter over all (αβ) voltage hexagon modulation regions, the LuPWM technique is selected for the tested IPMSM drive. Firstly, the scalar implementation of this LuPWM technique using the sine triangle waveform modulation technique on a simulation model of a resistor-inductor (R-L) inductive load is validated with sinusoidal current waveforms. However, implementation of the LuPWM in the closed loop control system of the tested IPMSM drive results in a considerable unexpected distortion in the phase current waveforms especially at low demanded torques. A study on this issue shows that due to the unavoidable ripples on the electrical angle position information leading to the malfunction on determining the (αβ) voltage hexagon sectors, the sector transition point of the LuPWM pulses especially when the state of the LuPWM pulse is changed between On-state and Off-state is strongly affected. Consequently, the current waveforms for a closed-loop drive system under the LuPWM technique during the sectors transition period become seriously distorted. In this thesis, the LuPWM current waveforms distortion problem is proposed to be addressed by modifying the pulse pattern of the traditional LuPWM technique around the (αβ) voltage hexagon sectors transition points associated with significant current waveforms distortion as aforementioned. Under this proposed PWM technique denoted as Mod-LuPWM technique, the switching state of each LuPWM pulse is suggested to be hold for an optimum small period around each transition period. Hence, the adverse effects of the angular ripple and the voltage error will be evened out between the “Turn-On” and “Turn-Off” transitions. Therefore, sinusoidal current waveforms can be obtained for closed-loop drive system under the proposed Mod-LuPWM. In addition, similar to the traditional LuPWM the Mod-LuPWM technique own the ability of on reducing the peak-to-peak common mode voltage value to one sixth of the DC-link voltage compared with the traditional PWMs. On the other hand, due to its switching characteristics, the switching losses of the drive system under the Mod-LuPWM technique are also reduced by one third during the switching period leading to an increase on the switching device life-time. Furthermore, as its implementation does not require any additional hardware, the proposed Mod-LuPWM can be employed for any existing drive system without any increase in the total drive cost. The proposed Mod-LuPWM has been validated with well-matched between simulation and experimental results showing significant current waveform improvements and considerable CMV reduction