This article aims to present a comprehensive approach with corresponding software that uses index matrices. They have been developed by the authors for an automated model-based design. One of the main goals of this paper is to propose a simple model solving technique for powering electronic devices (particularly, for all subsystems: power supplies, static power converters, electric filters, electrical loads, control systems, etc.). Index matrices, which contain first-order discrete dynamical system parameters, with real numbers as elements, are constructed in order so that voltages, amperages, and discrete values can be calculated. Simulations on a three-phase converter, as well as simulations on buck and boost DC-DC converters with PI controllers, are presented. The function of the proposed software (with examples on the aforementioned devices) is considered, and diagrams of its basic programming classes are shown. The latter draws electronic schemes and their respective graphics, and provides important characteristics. Simulink is used to verify results. Advantages of the proposed approach are a higher speed of calculations (compared to Simulink, due to a lack of differential equations) and a simpler handling of various electronic components. Additionally, a computational scalability is demonstrated.