Development of an image converter of radical design

A long term investigation of thin film sensors, monolithic photo-field effect transistors, and epitaxially diffused phototransistors and photodiodes to meet requirements to produce acceptable all solid state, electronically scanned imaging system, led to the production of an advanced engineering model camera which employs a 200,000 element phototransistor array (organized in a matrix of 400 rows by 500 columns) to secure resolution comparable to commercial television. The full investigation is described for the period July 1962 through July 1972, and covers the following broad topics in detail: (1) sensor monoliths; (2) fabrication technology; (3) functional theory; (4) system methodology; and (5) deployment profile. A summary of the work and conclusions are given, along with extensive schematic diagrams of the final solid state imaging system product

Design and Advanced Model Predictive Control of Wide Bandgap Based Power Converters

The field of power electronics (PE) is experiencing a revolution by harnessing the superior technical characteristics of wide-band gap (WBG) materials, namely Silicone Carbide (SiC) and Gallium Nitride (GaN). Semiconductor devices devised using WBG materials enable high temperature operation at reduced footprint, offer higher blocking voltages, and operate at much higher switching frequencies compared to conventional Silicon (Si) based counterpart. These characteristics are highly desirable as they allow converter designs for challenging applications such as more-electric-aircraft (MEA), electric vehicle (EV) power train, and the like. This dissertation presents designs of a WBG based power converters for a 1 MW, 1 MHz ultra-fast offboard EV charger, and 250 kW integrated modular motor drive (IMMD) for a MEA application. The goal of these designs is to demonstrate the superior power density and efficiency that are achievable by leveraging the power of SiC and GaN semiconductors. Ultra-fast EV charging is expected to alleviate the challenge of range anxiety , which is currently hindering the mass adoption of EVs in automotive market. The power converter design presented in the dissertation utilizes SiC MOSFETs embedded in a topology that is a modification of the conventional three-level (3L) active neutral-point clamped (ANPC) converter. A novel phase-shifted modulation scheme presented alongside the design allows converter operation at switching frequency of 1 MHz, thereby miniaturizing the grid-side filter to enhance the power density. IMMDs combine the power electronic drive and the electric machine into a single unit, and thus is an efficient solution to realize the electrification of aircraft. The IMMD design presented in the dissertation uses GaN devices embedded in a stacked modular full-bridge converter topology to individually drive each of the motor coils. Various issues and solutions, pertaining to paralleling of GaN devices to meet the high current requirements are also addressed in the thesis. Experimental prototypes of the SiC ultra-fast EV charger and GaN IMMD were built, and the results confirm the efficacy of the proposed designs. Model predictive control (MPC) is a nonlinear control technique that has been widely investigated for various power electronic applications in the past decade. MPC exploits the discrete nature of power converters to make control decisions using a cost function. The controller offers various advantages over, e.g., linear PI controllers in terms of fast dynamic response, identical performance at a reduced switching frequency, and ease of applicability to MIMO applications. This dissertation also investigates MPC for key power electronic applications, such as, grid-tied VSC with an LCL filter and multilevel VSI with an LC filter. By implementing high performance MPC controllers on WBG based power converters, it is possible to formulate designs capable of fast dynamic tracking, high power operation at reduced THD, and increased power density

Double Resonant High-Frequency Converters for Wireless Power Transfer

This thesis describes novel techniques and developments in the design and implementation of a low power radio frequency (40kHz to 1MHz) wireless power transfer (WPT) system, with an application in the wireless charging of autonomous drones without physical connection to its on-board Battery Management System (BMS). The WPT system is developed around a matrix converter exploiting the benefits such as a small footprint (DC-link free), high efficiency and high power density. The overall WPT system topology discussed in this thesis is based on the current state-of-the-art found in literature, but enhancements are made through novel methods to further improve the converter’s stability, reduce control complexity and improve the wireless power efficiency. In this work, each part of the system is analysed and novel techniques are proposed to achieve improvements. The WPT system design methodology presented in this thesis commences with the use of a conventional full-bridge converter. For cost-efficiency and to improve the converters stability, a novel gate drive circuit is presented which provides self-generated negative bias such that a bipolar MOSFET drive can be driven without an additional voltage source or magnetic component. The switching control sequences for both a full-bridge and single phase to single phase matrix converter are analysed which show that the switching of a matrix converter can be considered to be the same as a full-bridge converter under certain conditions. A middleware is then presented that reduces the complexity of the control required for a matrix converter and enables control by a conventional full-bridge controller (i.e. linear controller or microcontroller). A novel technique that can maximise and maintain in real-time the WPT efficiency is presented using a maximum efficiency point tracking approach. A detailed study of potential issues that may affect the implementation of this novel approach are presented and new solutions are proposed. A novel wireless pseudo-synchronous sampling method is presented and implemented on a prototype system to realise the maximum efficiency point tracking approach. Finally, a new hybrid wireless phase-locked loop is presented and implemented to minimise the bandwidth requirements of the maximum efficiency point tracking approach. The performance and methods for implementation of the novel concepts introduced in this thesis are demonstrated through a number of prototypes that were built. These include a matrix converter and two full WPT systems with operating frequencies ranging from sub-megahertz to megahertz level. Moreover, the final prototype is applied to the charging of a quadcopter battery pack to successfully charge the pack wirelessly whilst actively balancing the cells. Hence, fast battery charging and cell balancing, which conventionally requires battery removal, can be achieved without re-balance the weight of the UAV

Eksperimentalno ponašanje prototipa matričnog pretvarača izvedenog s novim energetskim modulima

This paper describes the design and the solutions adopted for a matrix converter prototype of 10 kW, based on new integrated power modules. The performance of the converter is verified by means of experimental tests.Članak opisuje projekt i rješenja usvojena za prototip 10 kW matričnog pretvarača, izvedenog s novim integriranim energetskim modulima. Svojstva pretvarača provjerena su eksperimentalnim ispitivanjima

Matrix converter open circuit fault diagnosis with asymmetric one zero SVM

An open-circuit fault detection and diagnosis strategy for a direct matrix converter is proposed in this paper. The current recirculating path during an open circuit condition is considered in detail with the aim of contributing more expert knowledge to the fault detection system for matrix converter. Simulation results are presented demonstrate the open circuit fault behavior of matrix converter. This expert knowledge is extremely important for the fault detection system to avoid false diagnosis. This work leads to the presentation of a reliable and fast fault detector for the Matrix Converter

Matrix converter open circuit behavior analysis

The matrix converter current recirculating path during an open circuit condition is given in detail with the aim of contributing more expert knowledge to a fault detection system for matrix converter. Simulation results were obtained demonstrating how current recirculates in the matrix converter and the clamp circuit during an open-circuit fault. Healthy output phase currents can be canceled to zero due to current recirculating via the clamp circuit. This result could contribute expert knowledge to a fault detection system to avoid false fault detection and diagnosis

Adaptive Neuro Fuzzy Technique for Speed Control of Six-Step Brushless DC Motor

The brushless DC motors with permanent magnets (PM-BLDC) are widely used in a miscellaneous of industrial applications. In this paper, The adaptive neuro fuzzy inference system (ANFIS) controller for Six-Step Brushless DC Motor Drive is introduced. The brushless DC motor’s dynamic characteristics such as torque , current , speed, , and inverter component voltages are showed and analysed using MATLAB simulation. The  propotional-integral (PI) and fuzzy system controllers  are developed., based on designer’s test and error process and experts. The  experimential and hardware resuts for the inverter- driver circuits are presented. The simulation results using MATLAB simulink are conducted to validate the proposed (ANFIS) controller’s robustness and high performance relative to other controllers

Finite Control Set Model Predictive Control Of Direct Matrix Converter And Dual-Output Power Converters

Model Predictive Control (MPC) with a finite control set has been successfully applied to several power converter topologies as reported in the scientific literature and research activity on predictive control techniques has increased over the last few years. MPC uses a discrete-time model of the system to predict future values of control variables for all possible control actions and computes a cost function related to control objectives to find the optimal control action. The control action which minimizes the cost function is selected and applied to the system for the next time interval. Different control objectives can be introduced in the user-defined cost function and controlled simultaneously by solving the multi-objective optimization problem. This approach is particularly advantageous for certain power converter topologies, such as Direct Matrix Converter (DMC) and dual-output power converters, for which conventional control techniques require complicated Pulse Width Modulation (PWM) schemes and multi-loop control, incurring high computational burden and complexity. Conversely, since MPC does not need a modulator to generate switching signals, implementation of the MPC technique is simple and intuitive. However, the MPC method also has several drawbacks:1. Real-time implementation of MPC incurs high computational burden2. There is no analytical procedure to adjust the weighting factors for multi-objective optimization problem3. A complete system model must be derived since MPC method uses this model to predict control variables4. MPC implementation is not straightforward for several power converter topologies, such as dual-output power converters. In this dissertation four specific contributions are reported that address these drawbacks. First, a fully FPGA-based real-time implementation of model predictive controller is proposed for direct matrix converter. In conventional real-time implementation of model predictive control method, Digital Signal Processors (DSPs) and Field-Programmable Gate Arrays (FPGA) are both used to ensure fast processing operation and preserve performance of the predictive controller. For the proposed, real-time implementation method, all control calculations and the safe commutation scheme for DMC are fully implemented in the FPGA and the need for a DSP is eliminated. Advantages of the proposed approach are simplicity and the ability to exploit the parallel computation capability of the FPGA to calculate in parallel the predictive state for all switch combination. This translates in a significant reduction of required computation time and potentially in reduced control hardware cost. Second, a novel model predictive control scheme for the three-phase direct matrix converter based on switching state elimination is proposed. The conventional MPC solves a multi-objective optimization problem by minimizing a multi-objective cost function over a one-step horizon. The control performance is strongly affected by the weighting factors used in the cost function and this is problematic. The proposed method solves this difficulty by eliminating the weighting factors and using a state elimination method based on error constraints that have a clear physical interpretation. Third, the model predictive control scheme is proposed for Nine-Switch Inverter (NSI) under an unknown load condition. Nine-switch inverter is a dual-output inverter and the proposed method can control two three-phase load simultaneously by solving single optimization problem. In power electronics applications, control of the power converter must work well under all load conditions and the control method should provide clean power no matter what the load is. In this work, two ac load currents are estimated using full-order observers and converter is controlled by using model predictive control method. Fourth, the model predictive control scheme is proposed for dual-output Indirect Matrix Converter (IMC). Modulation method for this topology is complicated and conventional linear control techniques require tuning of the controller parameters. In conventional control technique, multi-loop control is required to independently adjust the two ac outputs. The usage of multi-loop control techniques increases the complexity of implementation of the controller. On the other hand, proposed method can achieve several control goals by using single control loop and provide good system performance

Two decades of condition monitoring methods for power devices

Condition monitoring (CM) of power semiconductor devices enhances converter reliability and customer service. Many studies have investigated the semiconductor devices failure modes, the sensor technologies, and the signal processing techniques to optimize the CM. Furthermore, the improvement of power devices’ CM thanks to the use of the Internet of Things and artificial intelligence technologies is rising in smart grids, transportation electrification, and so on. These technologies will be widespread in the future, where more and more smart techniques and smart sensors will enable a better estimation of the state of the health (SOH) of the devices. Considering the increasing use of power converters, CM is essential as the analysis of the data obtained from multiple sensors enables the prediction of the SOH, which, in turn, enables to properly schedule the maintenance, i.e., accounting for the trade-off between the maintenance cost and the cost and issues due to the device failure. From this perspective, this review paper summarizes past developments and recent advances of the various methods with the aim of describing the current state-of-the-art in CM research