There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

[신간의 별자리x] 우리/미술, 그리고 ‘슬픔의 박물관’

This paper presents a detailed description of finite control set model predictive control (FCS-MPC) applied to power converters Several key aspects related to this methodology are, in depth, presented and compared with traditional power converter control techniques, such as linear controllers with pulsewidth-modulation-based methods The basic concepts, operating principles, control diagrams, and results are used to provide a comparison between the different control strategies The analysis is performed on a traditional three-phase voltage source inverter, used as a simple and comprehensive reference frame However, additional topologies and power systems are addressed to highlight differences, potentialities, and challenges of FCS-MPC Among the conclusions are the feasibility and great potential of FCS-MPC due to present-day signal-processing capabilities, particularly for power systems with a reduced number of switching states and more complex operating principles, such as matrix converters In addition, the possibility to address different or additional control objectives easily in a single cost function enables a simple, flexible, and improved performance controller for power-conversion systems

Model Predictive Control—A Simple and Powerful Method to Control Power Converters

Predictive control is a very wide class of controllers that have found rather recent application in the control of power converters. Research on this topic has been increased in the last years due to the possibilities of today's microprocessors used for the control. This paper presents the application of different predictive control methods to power electronics and drives. A simple classification of the most important types of predictive control is introduced, and each one of them is explained including some application examples. Predictive control presents several advantages that make it suitable for the control of power converters and drives. The different control schemes and applications presented in this paper illustrate the effectiveness and flexibility of predictive control.

Predictive Control in Power Electronics and Drives

This paper presents a predictive current control method and its application to a voltage source inverter. The method uses a discrete-time model of the system to predict the future value of the load current for all possible voltage vectors generated by the inverter. The voltage vector which minimizes a quality function is selected. The quality function used in this work evaluates the current error at the next sampling time. The performance of the proposed predictive control method is compared with hysteresis and pulsewidth modulation control. The results show that the predictive method controls very effectively the load current and performs very well compared with the classical solutions

Predictive Current Control of a Voltage Source Inverter

In this paper, a new optimal two-switching cycle compensation algorithm is proposed to achieve optimal transient performance for DC-DC converters under an input voltage change. Using the principle of capacitor charge balance, the proposed algorithm predicts the optimized two-switching cycle duty cycle series to drive the output voltage back to the steady state when the input voltage changes. Experiments are performed in a 2.5 V, 10 A, synchronous buck converter to verify the effectiveness of the proposed algorithm. The results show that using the proposed algorithm, good dynamic performance, including as small overshoot/undershoot and short recovery time is achieved.

A digital control algorithm for DC-DC converters under input voltage changes

Two-phase Three-dimension (3D) common inductor LLC resonant converter is proposed to achieve automatic current sharing. The series inductor of each phase are connected by a Coupled impedance which is inductor, capacitor or short-circuit. A Coupled index is indicated to analyze the current sharing performance under three types converter based on the Fundamental Harmonic Analysis (FHA). The previous method only work at Coupled index equals to 1 and 0, However, the Coupled index can be design any value in (−∞, +∞) for two-phase 3D common inductor LLC converter, and the current sharing performance is better if the Coupled index is designed in negative value. Four steady-state operations under Coupled index is 1, 0.5, 0, −1 are discussed to verify the current sharing improving. A 600W, 12V two-phase LLC converter with short-circuit Coupled impedance prototype is built. The prototype verified the feasibility and demonstrated advantages of the proposed converter.

Two-phase three-dimension common inductor LLC resonant converter with automatic current sharing

In this paper, a new configuration called the auto disturbance rejection controller (ADRC) is used in induction motor speed control. The key part of the ADRC is the extended state observer (ESO). By using ESO, the ADRC can estimate accurately the derivative signals and accurate decoupling of the induction motor is also achieved. In addition, the external disturbances and parameter variations could also be estimated and compensated by ADRC, so that the closed loop motor drive system under ADRC control does not depend on the accurate mathematical model of induction motors. Therefore, the robustness and adaptability of the control system is improved too. The simulation and experiment results show that the controller operates quite robustly under modeling uncertainty and external disturbance, and it can provide good dynamic performance such as small overshoot and fast transient time in the speed control.

An improved nonlinear control strategy for induction motor drive

DC microgrids (MGs) have many potential advantages compared with AC microgrids, which have attracted more and more attention in recent years. However, DC bus voltage control of these systems can be an important issue undergoing the power surplus or deficit. An energy buffer in the DC MG powered by the bidirectional DC/DC converter with energy storage systems (ESS) such as super capacitor were investigated. In this paper, a novel hybrid control algorithm based on capacitor charge balance control (CBC) for the bidirectional DC/DC converter to achieve near-optimal dynamic performance is presented. A hybrid control strategy is proposed in order to make the DC MG recover from a sudden bus current step change with the smallest voltage deviation in the shortest settling time. And a set of equations are developed to design the proposed hybrid controller. The effectiveness and the fast transient performance of the proposed hybrid approach has been verified by PSIM simulation results.

Digital capacitor charge balance control strategy of bidirectional DC/DC converter in DC microgrid

The switched-capacitor converter (SCC) topology has been gaining attention in recent years because of their advantages of higher power density, switch utilization, and reduced component stress compared to existing converter topologies. However, SCCs have a major drawback in which capacitor charge redistribution results in significant current spikes. One method of addressing charge redistribution is split-phase operation, which accomplishes this by imposing voltage control on the SCC’s flying capacitors. However, an important design consideration was identified regarding the implementation of the split-phase Dickson SCC in high-current applications. Mismatched flying capacitors exhibit uneven charge rates, resulting in incomplete elimination of charge redistribution by split-phase control. This paper presents a discussion of the effects of mismatched flying capacitors on the operation of the split-phase Dickson SCC. Furthermore, design processes and test results of a prototype high-current split-phase Dickson SCC will be presented.

Yan-Fei Liu

Papers

A digital control algorithm for DC-DC converters under input voltage changes

Two-phase three-dimension common inductor LLC resonant converter with automatic current sharing

An improved nonlinear control strategy for induction motor drive

Digital capacitor charge balance control strategy of bidirectional DC/DC converter in DC microgrid

Optimization and Design of a 48-to-12 V, 35 A Split-Phase Dickson Switched-Capacitor Converter