Assessment of novel power electronic converters for drives applications

Phd ThesisIn the last twenty years, industrial and academic research has produced over one hundred new converter topologies for drives applications. Regrettably, most of the published work has been directed towards a single topology, giving an overall impression of a large number of unconnected, competing techniques. To provide insight into this wide ranging subject area, an overview of converter topologies is presented. Each topology is classified according to its mode of operation and a family tree is derived encompassing all converter types. Selected converters in each class are analysed, simulated and key operational characteristics identified. Issues associated with the practical implementation of analysed topologies are discussed in detail. Of all AC-AC conversion techniques, it is concluded that softswitching converter topologies offer the most attractive alternative to the standard hard switched converter in the power range up to 100kW because of their high performance to cost ratio. Of the softswitching converters, resonant dc-link topologies are shown to produce the poorest output performance although they offer the cheapest solution. Auxiliary pole commutated inverters, on the other hand, can achieve levels of performance approaching those of the hard switched topology while retaining the benefits of softswitching. It is concluded that the auxiliary commutated resonant pole inverter (ACPI) topology offers the greatest potential for exploitation in spite of its relatively high capital cost. Experimental results are presented for a 20kW hard switched inverter and an equivalent 20kW ACPI. In each case the converter controller is implanted using a digital signal processor. For the ACPI, a new control scheme, which eliminates the need for switch current and voltage sensors, is implemented. Results show that the ACPI produces lower overall losses when compared to its hardswitching counterpart. In addition, device voltage stress, output dv/dt and levels of high frequency output harmonics are all reduced. Finally, it is concluded that modularisation of the active devices, optimisation of semiconductor design and a reduction in the number of additional sensors through the use of novel control methods, such as those presented, will all play a part in the realisation of an economically viable system.Research Committee of the University of Newcastle upon Tyn

SCR-Based Wind Energy Conversion Circuitry and Controls for DC Distributed Wind Farms

The current state of art for electrical power generated by wind generators are in alternating current (AC). Wind farms distribute this power as 3-phase AC. There are inherent stability issues with AC power distribution. The grid power transfer capacity is limited by the distance and characteristic impedance of the lines. Furthermore, wind generators have to implement complicated, costly, and inefficient back-to-back converters to generate AC. AC distribution does not offer an easy integration of energy storage. To mitigate drawbacks with AC generation and distribution, direct current (DC) generation and high voltage direct current (HVDC) distribution for the wind farms is proposed. DC power distribution is inherently stable. The generators convert AC power to DC without the use of a back-to-back converter. DC grid offers an easy integration of energy storage. The proposed configuration for the generator is connected to a HVDC bus using a 12 pulse thyristor network, which can apply Maximum Power Point Tracking (MPPT). To properly control the system, several estimators are designed and applied. This includes a firing angle, generator output voltage, and DC current estimators to reduce noise effects. A DSP-based controller is designed and implemented to control the system and provide gate pulses. Performance of the proposed system under faults and drive train torque pulsation are analyzed as well. Additionally, converter paralleling when turbines operate at different electrical power levels are also studied. The proposed new Wind Energy Conversion System (WECS) is described in detail and verified using MATLAB®/ Simulink® simulation and experimental test setup. The proposed solution offers higher reliability, lower conversion power loss, and lower cost. The following is proposed as future work: 1) Study different control methods for controlling the SCR\u27s. 2) Investigate reducing torque pulsations of the PMSG and using the proposed power conversion method for DFIG turbines. 3) Explore options for communication/control between PMSG, circuit protection and grid-tied inverters. 4) Investigate the best possible configuration for DC storage/connection to the HVDC/MVDC bus. 5) Study the filtering needed to improve the DC bus voltage at the generator

Modeling and control of a brushless DC motor

Permanent magnet brushless DC motors (PMBLDC) find wide applications in industries due to their high power density and ease of control. These motors are generally controlled using a three phase power semiconductor bridge. For starting and the providing proper commutation sequence to turn on the power devices in the inverter bridge the rotor position sensors required. Based on the rotor position, the power devices are commutated sequentially every 60 degrees. To achieve desired level of performance the motor requires suitable speed controllers. In case of permanent magnet motors, usually speed control is achieved by using proportional-integral(PI) controller. Although conventional PI controllers are widely used in the industry due to their simple control structure and ease of implementation, these controllers pose difficulties where there are some control complexity such as nonlinearity, load disturbances and parametric variations. Moreover PI controllers require precise linear mathematical models. This thesis presents a Fuzzy Logic Controller(FLC) for speed control of a BLDC by using. The Fuzzy Logic(FL) approach applied to speed control leads to an improved dynamic behavior of the motor drive system and an immune to load perturbations and parameter variations. The FLC is designed using based on a simple analogy between the control surfaces of the FLC and a given Proportional-Integral controller(PIC) for the same application. Fuzzy logic control offers an improvement in the quality of the speed response, compared to PI control. This work focuses on investigation and evaluation of the performance of a permanent magnet brushless DC motor (PMBLDC) drive, controlled by PI, and Fuzzy logic speed controllers. The Controllers are for the PMBLDC motor drive simulated using MATLAB soft ware package. Further, the PI controller has been implemented on an experimental BLDC motor set up

Phase II CRADA ORNL99-0568 Report : Developing Transmission-Less Inverter Drive Systems for Axial-Gap Permanent magnet Accessory and Traction Motors and Generators

Researchers of the Oak Ridge National Laboratory's (ORNLs) Power Electronics and Electric Machine Research Center (PEEMRC) collaborated with Visual Computing Systems (VCS) to develop an electric axial-gap permanent magnet (PM) motor controlled by a self-sensing inverter for driving vehicle accessories such as power steering, air conditioning, and brakes. VCS designed an 8 kW motor based on their Segmented Electromagnetic Array (SEMA) technology. ORNL designed a 10 kW inverter to fit within the volume of a housing, which had been integrated with the motor. This modular design was pursued so that multiple modules could be used for higher power applications. ORNL built the first inverter under the cooperative research and development agreement (CRADA) ORNL 98-0514 and drove a refurbished Delta motor with no load during the Merit Review at ORNL on Monday, May 17, 1999. Inverter circuitry and instructions for assembling the inverters were sent to VCS. A report was prepared and delivered during the Future Car Congress in April 2000, at Arlington, Virginia. Collaboration continued under CRADA ORNL 99-0568 as VCS designed and built a SEMA motor with a dual coil platter to be the traction motor for an electric truck. VCS and ORNL assembled two 45 kW inverters. Each inverter drove one coil, which was designed to deliver 15 kW continuous power and 45 kW peak power for 90 s. The vehicle was road tested as part of the Future Truck Competition. A report was prepared and delivered during the PCIM in October 2000, at Boston, Massachusetts

A matrix converter drive system for an aircraft rudder electro-mechanical actuator

The matrix converter is an attractive topology of power converter for the Aerospace Industry where factors such as the absence of electrolytic capacitors, the potentiality of increasing power density, reducing size and weight and good input power quality are fundamental. The matrix converter potential advantages offers the possibility to achieve the aim of the More Electric Aircraft research which intends to gradually re- place, from the aircraft architecture, the hydraulic power source and its infrastructure with electric power generation and a more flexible power distribution system. The purpose of this work is to investigate the design and implementation of a 40kVA matrix converter for an Electro Mechanical Actuator (EMA) drive system. A SABER simulation analysis of the candidate matrix converter drive systems, for this application, is provided. The design and implementation of the matrix converter is described, with particular attention to the strict requirements of the given aerospace application. Finally, the matrix converter PMSM drive system and the EMA drive system are respectively assembled, tested and commissioned

Processor evaluation for low power frequency converter product family

Tässä työssä tutkitaan markkinoilla olevia tai lähitulevaisuudessa markkinoille saapuvia prosessoreja käytettäväksi pienitehoisissa taajuusmuuttajissa. Tutkimuksen tarkoitus on selvittää prosessorin sopivuutta sovellukseen, jossa hinta on merkittävä tekijä. Tutkimuksessa esitettyjen vaatimusten perusteella houkuttelevimmat prosessorit otetaan tarkempaan tutkimukseen. Tarkemman selvityksen jälkeen vaatimuksia teknisesti mahdollisimman tarkasti vastaavat prosessorit pyydettiin valmistajalta testattavaksi. Testaaminen suoritettiin lopulta viidelle eri prosessorille, joista kaksi perustui samaan ytimeen. Testaamisen tavoitteena on selvittää prosessorin sopivuus käyttökohteeseensa. Sopivuus testattiin suorittamalla prosessoreissa taajuusmuuttajakäyttöä mallintavaa testikoodia. Tuloksina testikoodin ajamisesta saatiin tietyissä aliohjelmissa kulutettu aika sekä kulutetut kellosyklit. Suorituskyvyn lisäksi testaukseen kuului prosessorikohtaisen kääntäjän aikaansaaman koodin koko. Aliohjelmat sisälsivät sekä aritmeettisia, että loogisia operaatioita, joiden kombinaationa mahdollisimman hyvä sopivuus saatiin selvitettyä.The aim of this thesis is to study processors to be used in a low power frequency converter. Processors under investigation must be currently or in the near future in the market. The purpose is to examine suitability of a processor to an application in which price is an essential factor. The requirements presented in this study will determine which processor will be reviewed more closely. After a precise review, processor vendors was asked to provide as corresponding device as possible to a test. Testing was accomplished eventually with five different processors of which two were based on a same core. The aim of the testing was to investigate suitability of the processors to their target task. Suitability was tested by executing code that models frequency converter application. As a result, spent time and clock cycles are presented in certain functions. In addition to performance, the testing included evaluation of the size of the output code the compilers created. Functions under test consisted of a combination of arithmetic and logic operations that was used to interpret the suitability of the processor

IMECE2004-60060 DESIGN OF A SPATIAL LINKAGE HAPTIC INTERFACE

ABSTRACT This paper describes the mechanical and electrical design of a compact high fidelity desktop haptic interface that provides three-degree-of-freedom point-force interaction through a handheld pen-like stylus. The complete haptic device combines a spatial linkage, actuation, power amplification, and control electronics in a standalone package with a footprint similar to that of a notebook computer (33cm x 25cm x 10cm). The procedure used to design the statically balanced spatial linkage is explained and both an inexpensive lightweight plastic version and a high stiffness, high strength, aluminum and stainless steel version are presented. The theory and implementation of sinusoidal encoder interpolation and sinusoidal servo-motor commutation used to achieve high-fidelity haptic simulation is covered for two versions of electronic control hardware: custom hardware based on a digital signal processor (DSP) and an off-the-shelf design based on an embedded PC

A matrix converter drive system for an aircraft rudder electro-mechanical actuator

The matrix converter is an attractive topology of power converter for the Aerospace Industry where factors such as the absence of electrolytic capacitors, the potentiality of increasing power density, reducing size and weight and good input power quality are fundamental. The matrix converter potential advantages offers the possibility to achieve the aim of the More Electric Aircraft research which intends to gradually re- place, from the aircraft architecture, the hydraulic power source and its infrastructure with electric power generation and a more flexible power distribution system. The purpose of this work is to investigate the design and implementation of a 40kVA matrix converter for an Electro Mechanical Actuator (EMA) drive system. A SABER simulation analysis of the candidate matrix converter drive systems, for this application, is provided. The design and implementation of the matrix converter is described, with particular attention to the strict requirements of the given aerospace application. Finally, the matrix converter PMSM drive system and the EMA drive system are respectively assembled, tested and commissioned