The shortage of energy and concern for the environment due to the release of harmful gases created by the burning of huge amounts of fossil fuels have become the primary problems for humanity as a whole and a great challenge for scientists. Hybrid technology takes on an increasingly important role in trying to solve these problems. Since the transport sector is the largest consumer of fossil fuels, major scientific efforts are being invested in the development of hybrid drivetrain for vehicles. The biggest flaw of existing hybrid drivetrain is dual energy transformation, mechanical to electric and vice versa, and DC to AC and vice versa. With the purpose of reducing disadvantages of existing drivetrain, a new configuration of electromechanical drivetrain for hybrid electric vehicles is proposed in this paper, which is capable of securing greater energy efficiency and lower emission of harmful gases from existing systems for each speed of the vehicle. With this, the planetary drivetrain allows independence of the rotation speed of the shaft of the engine with internal combustion for the speed of the vehicle, enabling minimal fuel consumption for each vehicle load. In addition, with the help of a simple management strategy, the entire energy system is optimized for maximum usability. Energy flows and main system features are analyzed based on simulation results of a dynamic model developed in Matlab/Simulink, where complex mechanical and electrical components (internal combustion engine, electric motor control, control generator and drive battery) are modelled on data extracted from the program package ADVISOR, developed by the US National Renewable Energy Laboratory. The results were compared with a few existing drivetrain systems for the purpose of assessing the quality of the new drivetrain for hybrid electric vehicles. It has been shown that a vehicle with a new drivetrain achieves superior results in the vast majority of comparable categories compared to vehicles that use the current drivetrain and energy conversion systems.