Paul Michael Szczesny

Microcomputer Control of a Residential Photovoltaic Power Conditioning System

Microcomputer-based control of a residential photovoltaic power conditioning system is described. The microcomputer is responsible for array current feedback control, maximum power tracking control, array safe zone steering control, phase-locked reference wave synthesis, sequencing control, and some diagnostics. The control functions are implemented using Intel 8751 single-chip microcomputer-based hardware and software. The controller has been tested in the laboratory with the prototype power conditioner and shows excellent performance.

Microcomputer Control of Switched Reluctance Motor

A microcomputer-based four-quadrant control system of a switched reluctance motor is described. The control was implemented with a speed feedback loop, a torque feedback loop, and both the torque and speed feedback loops combined. In addition the controller incorporates a startup operation, sequencing, and synchronized angle steering control. The angle controller was designed using dedicated digital hardware, whereas the other functions were implemented using an Intel 8751 single-chip microcomputer. The complete control system was tested in the laboratory with a 5-hp drive, and the test results were found to be excellent.

System design considerations for a high-power aerospace resonant link converter

A novel variable-speed, constant-frequency (VSCF) 400 Hz aircraft generating system has been developed using an actively clamped resonant DC link converter. The design approach used to select the best configuration for the resonant converter power stage is described, including techniques for choosing power component values to meet key governing performance specifications. Interactions between the various converter components are discussed, suggesting approaches for selecting values which must meet multiple and sometimes conflicting system performance criteria. Verification is provided using a combination of simulation results and test data from a 60 kVA laboratory breadboard system.<<ETX>>

Input voltage pumping control for a multi-level switching amplifier

The paper describes energy pumping among dc busses in a multilevel inverter with isolated power supplies driving a passive load, and an algorithm to eliminate it. In the current switching amplifier application, the output current waveforms are required to be of almost arbitrary shape. Modulation techniques are known to be well suited for conventional inverter operation, however when driving some output current waveforms, they can produce dc bus over voltages due to an undesired energy transfer between busses. The specific cases that cause the pumping are described and an algorithm is proposed that eliminates the effect without disturbing the correct operation of the inverter. The algorithms have been tested in a prototype to verify the expected performance.

Dead-time compensation for a high-fidelity voltage fed inverter

The paper presents an improved method to accurately compensate the dead time effects on a voltage fed inverter for a magnetic resonance imaging (MRI) gradient driver. MRI systems require very high accuracy, errors in the milliamps range, and integral current errors of a few tens of muAs, with output currents of several hundred amperes. In order to achieve the bandwidth required and minimize the output filter size, the ripple frequency is 125 kHz or higher. The power architecture consists of three full-bridges in a stack configuration with a modulation technique that results on current ripple very dependent on the operating point. The accuracy requirement, combined with high power, 1 MVA, high switching frequency, and arbitrary output waveforms, makes compensation crucial and very challenging. The standard techniques for dead time compensation do not meet the required specifications. A new technique based on conventional approaches with a correction based on experimental results is proposed to significantly reduce the transient errors. The new algorithm has been tested on the real gradient driver, and has shown the peak integral error reductions of more than 50%. The system thus configured fully meets the requirements for image quality in the MRI system.

High-fidelity and high-speed modeling and simulation for power conversion systems

High fidelity and high-speed modeling and simulation are essential analytical tools for the design of sophisticated large-scale power conversion systems, like Oil and Gas compressor drives, Wind and Solar converters, and MRI gradient drivers. This paper presents various approaches to the dynamic modeling of power electronics components, new topologies and their control applicable to their system design and analysis. Discussions on the practical technical issues in the system modeling and simulation will also be presented, with a few demonstrative examples of the power converters in as used in power generation and in compressor drives for Oil and Gas.

Dynamic modeling of power electronic systems

Simulation and modeling provide a fast and cost-efficient way for sophisticated analysis and design of power converters. This paper presents various approaches of dynamic modeling of power electronic systems. It discusses practical technical issues in simulation and system modeling. Two demonstrative examples, the power converters in healthcare and energy systems, by using different simulation package and platforms are provided.