2016 ISCEE International Conference on the Science of Electrical Engineering Averbukh M. Department of Electrical/Electronic Engineering, Ariel University, Israel Abstract – One of the traditional difficulties in the courses “Power Electronics” and “Electrical Drives” is parameters estimation in the non-linear electronic schemes including inductances, capacitances, resistances as well as diodes and switches. These schemes could be found in equivalent circuits of electric motors and multiple electronic devices that are applicable in power electronics. Taking into account complications to solve non-linear ordinary differential equations (ODE) describing occurring processes and their parameters typical student has a problem to achieve analytical results. Numerous linearization methods were used in the past that was aiming to make things easier and this way to get roughly approximate however analytical solution. Today coarsely estimated results are inacceptable as a rule. Therefore, typical approach in this case is an application of simulation software programs such as PSIM, MATLAB Simulink, WOLFRAM Matematica and others giving excellent opportunity to get accurate answer. However, such numerical results are being extremely truthful aren't capable to allow visible representation of outcomes and this circumstance significantly decrease their value. In mentioned above courses of Power Electronics and Electrical Drives are learned in Ariel University a wide application are obtained methods of numerical nomograms with dimensionless representation of input-output parameters. Dimensionless approach allows significant diminishing of a number of involved variables and this way to simplify calculation. A usage of dimensionless method provides acceptable precision of results with the possibility to represent different parameter’s trends in wide range of input conditions. The possible objects of analysis could be for example, output character istics of DC motors fed by controllable and uncontrollable n-phase rectifiers, resistive rectifier losses and motor’s efficiency, and some others. Long time practice of these approaches approved their usefulness, productivity and helpfulness. Keywords – Dimensionless Nomogram, Power Electronics, Electrical Drives, Input-Output Parameters Estimation. I. INTRODUCTION Nomogram usage with dimension and dimensionless representation of involved parameters is well-known relatively long period of time. Power Electronics and Electrical Drives specialties applied and continue to use this method now. Numerous examples of nomogram practice could be found in multiple textbooks [1-3] and many others. Different scientific sources apply nomogram for development circuit parameters [4-6], for education purpose [7] and for estimation of output parameters for different power electronic circuits [8, 9]. Wide and mandatory use of numerical nomogram is presented in almost every engineering catalog and datasheets in electrical/electronic industry, for example [10-12]. Special attention has to be done to the nomogram applications for education process [7]. Theoretical solutions of AC-AC phase control scheme (single phase circuit) firstly are presented. Multiple graphs for assessment different circuit parameters that are based on the represented previously analytical solutions are given in the text for convenience. However, most of parameters are specified in dimension form that causing to enormous number of different graphs and nomogram and this significantly complicates suggested approach. In the present work some important examples of nomograms with dimensionless representation of involved parameters are shown. II. DC MOTOR IS FED BY N-PHASE RECTIFIER For example represented below dimensionless nomogram analysis of DC (external or permanent magnet excitation) motor is fed by single phase half period AC-DC rectifier (Fig.1). Fig.1. Equivalent circuit of DC (external or permanent magnet excitation) motor is fed by single phase rectifier. In the Fig.1 diode, equivalent armature resistance and inductance are designated as D, Ra, and La. Armature electromotive force (EMF) is labeled as Ea and is proportional to the motor rotation velocity ω M . Graph of a current and a voltage is shown in Fig.2 where α – control angle, β-extinction angle and γ is conducting angle. Dimensionless Nomogram Approach in the Courses of Power Electronics and Electrical Drives