Ismael Araujo-Vargas

Relative coupling strategy

Multi-motor arrangements have grown as an important field in the manufacturing process where high-performance applications that are able to achieve precise control of position, speed, acceleration, and deceleration are required. Several approaches exist for such synchronisation control all of them with the main aim to synchronize multiple machine axes and to emulate the actions of the mechanism they replace. However, so far little work has been done in the relative speed and position error between axes during the start-up, shutdown conditions and under load impacts on any motor. This paper present a novel multi-motor synchronisation strategy called relative coupled strategy, which can be easily applied into a real industrial environment. This novel approach is specifically compared with the electronic (virtual) line shaft. Results are presented showing the ability of the novel and current strategies to cope with different load conditions.

Capacitor Voltage-Balancing Techniques for a Multipulse Rectifier With Active Injection

Two techniques are presented to balance the filter capacitor voltages of a multipulse rectifier with the active injection operating on a variable-frequency supply. The active injector consists of a low-rated bidirectional switch that modifies the behavior of a 12-pulse rectifier at either low or high frequency, resulting in 24-pulse or multilevel pulse width modulation operation, respectively. The operation of the rectifier and the injector, the practical issues that unbalance the capacitor voltages, and the methods to correct this imbalance are explained together with experimental results obtained with a 4-kW prototype.

High-Performance Multipulse Rectifier With Single-Transistor Active Injection

A three-phase, multilevel rectifier using active voltage injection with one MOSFET device is presented. The injector consists of a bidirectional switch that modifies the behavior of a 12-pulse rectifier resulting in either 24-pulse or multilevel pulsewidth-modulated (PWM) operation. The resultant input currents are almost sinusoidal, the line current THD being 2.36% for 24-pulse operation and 1.06% for PWM operation. The MOSFET current is 2.9% of the load current. The circuit operation, idealized waveforms and modulation strategy are explained and experimental results are presented.

A Space Vector PWM algorithm for a hybrid multilevel inverter

The implementation of a Space Vector PWM (SVPWM) algorithm to generate the switching scheme for a multilevel hybrid inverter is presented in this paper. Unlike other multilevel inverters, a minimum number of switching devices, a split DC link, and a 50% rated, three-phase transformer are combined to generate seven-level SVPWM output voltage waveforms. The principle of operation and implementation of the algorithm are described in this paper along with simulation results obtained with a 1kW prototype for utility applications.

Capacitor voltage balancing techniques for a multi-pulse pulse rectifier with active injection

Two techniques are presented to balance the filter capacitor voltages of a multi-pulse rectifier with active injection operating on a variable frequency supply. The active injector consists of a low-rated, bidirectional switch that modifies the behaviour of a 12-pulse rectifier at either low or high-frequency, resulting in 24-pulse or multi-level PWM operation respectively. The operation of the rectifier and the injector, the practical issues that unbalance the capacitor voltages and the methods to correct this imbalance are explained together with experimental results obtained with a 4 kW prototype.

36-Pulse Hybrid Ripple Injection for High-Performance Aerospace Rectifiers

This paper presents a 3-phase, voltage-sourced, 36-pulse converter that draws almost sinusoidal currents. The converter results from the combination of a series connected, 12-pulse, voltage-sourced rectifier with a passive voltage injection circuit and a bi-directional switch. The voltage injection circuit uses a single-phase rectifier bridge and a single-phase transformer. Both the voltage injection circuit and the bi-directional switch operate at six times the supply frequency and have a low rating. In this paper, the converter operation is explained and analysed. Subsequently, the converter is evaluated experimentally using a 4 kW, 400 Hz prototype, where the THDI of the line currents was measured to be below 1.2%.

A Single DC-Source Seven-Level Inverter for Utility Equipment of Metro Railway, Power-Land Substations

This paper presents an unusual topology of a medium-power seven-level inverter that utilizes a single dc source and a three-phase transformer to generate high-performance seven-level voltage waveforms without complex cascade H-bridges with isolated dc supplies or neutral-point-clamped circuits with capacitor balancing techniques. In contrast to typical topologies of multilevel inverters, the control strategy of the presented circuit facilitates its implementation on a simple 16-bit microcontroller, such that the proposed inverter is operated under a space vector mode. The principle of operation of the seven-level inverter is analyzed, using idealized waveforms for easy and straight implementation together with a description of its practical development, showing experimental results obtained with a 1-kW prototype.

Control of a hybrid seven-level PWM inverter

A control strategy to operate a hybrid multilevel inverter is described in this paper. The inverter produces seven-level PWM voltage waveforms using twelve transistors and a three-phase transformer for harmonic elimination offering the following advantages: flying capacitors with neutral clamped circuits are not required, a small number of switching devices is used and the PWM switching losses are minimal. The proposed control technique is implemented on an 8 - bit microcontroller, and was designed to operate all the transistors of the converter using only one carrier and modulating signals, offering a simple control solution. The circuit operation and the design of the control principle are discussed in this paper together with experimental results obtained with a 1 kW prototype.

Design and Construction of a Three-Phase Transformer for a 1 kW Multi-level Converter

This paper describes the techniques used to design a three-phase transformer which is a fundamental component of a 1 kW multi-level inverter. The transformer interconnects the outputs of two 6-pulse inverters to produce 12-pulse voltage waveforms at the output. The transformer transfers half of the throughput power to the inverter output. The design and construction of a 500 VA three-phase transformer for a 1kW inverter is presented in this paper together with the practical issues and considerations to build a transformer prototype.

Space vector PWM strategy for a thirteen-level hybrid inverter

Multilevel Inverters are increasingly being used in high-power and medium voltage applications; there are many modulation techniques available to control their operation. In this paper, the Space Vector PWM Technique (SVPWM) to control a hybrid multilevel inverter is described. The inverter produces thirteen-level, SVPWM, three-phase waveforms using a bidirectional switch, twelve transistors and a delta-star transformer. The simulation and experimental results obtained with a 1 kW prototype are provided to verify the correct operation of the converter.