Dynamic performance of current control loop still remains crucial for position-, speed-, and torque-controlled drives. In the study, a current loop solution has been designed for field oriented control of permanent magnet synchronous motors (PMSM). It enhances typical PI controller with an estimator of zero-delay current (ZDC) value. The ZDC estimation allows for selecting substantially higher controller gain. It reduces control loop step response rise time to a single control cycle, which is the shortest technically possible value, while avoiding overshoot. The method does not require any hardware changes and it needs only negligible processing overhead. Both simulations made and experimental results obtained in the study have proved the effectiveness of the proposed solution.

Abstract:In-wheel electric drives are promising as actuators in active safety systems of electric and hybrid vehicles. This new function requires dedicated control algorithms, making it essential to deliver models that reflect better the wheel-torque control dynamics of electric drives. The timing of digital control events, whose importance is stressed in current research, still lacks an analytical description allowing for modeling its influence on control system dynamics. In this paper, authors investigate and compare approaches to the analog and discrete analytical modeling of torque control loop in digitally controlled electric drive. Five different analytical models of stator current torque component control are compared to judge their accuracy in representing drive control dynamics related to the timing of digital control events. The Bode characteristics and stepresponse characteristics of the analytical models are then compared with those of a reference model for three commonly used cases of motor discrete control schemes. Finally, the applicability of the presented models is discussed.

. I n t r o d u c t i o nThe art of programming includes knowledge of programming tools and languages, problem-solving skills, and effective strategies for program design and implementation. A common approach in programming education is to first teach the basics of a programming language and then guide students towards effective strategies for the whole programming process. Therefore, the learning of the basic concepts is often emphasized; these form the basis for building more advanced skills.Codewitz project [5] aims at fostering the learning of the basic concepts and structures by creating dynamic visual learning materials for students. In order to create effective visualizations and educational strategies for their use, it is necessary to review the research previously published in the field.This literature study aims at a brief overview on the problems and on visualization solutions in programming education. The emphasis is on novice programmers that are beginning their programming studies; these courses are often referred in the literature as CS1 courses. An excellent source for the study has been a recent review on the research relating to the educational study of programming, written by Robins et. al. [27]. Another vast source of information is an older collection of research papers on novice programmers, edited by Soloway and Spohrer [29]. Also the research by Milne and Rowe [21], who studied students' and tutors' perceptions of difficulties in object-oriented programming, relates closely to our work. However, their work differs from our needs analysis survey in that the group of respondents was considerably smaller (altogether 66 students and teachers) and the questions concentrated on the C++ language concepts. In addition, many other articles contain important information for the Codewitz-Minerva project and will be mentioned later.The structure of this study is organized as follows. First, Section 2 recognizes some characteristics and problems of novice programmers. In Section 3, we discuss educational visualization approaches for programming. Section 4 concludes the study and proposes some

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