Researches on power transmission systems of traction vehicles with a hybrid drive

The structures of modern traction vehicles are based on new generation devices. Technical progress within the field of power transmission concerns such elements as sources of power supply, electric devices and energy electronic solutions in power transmission systems. The prototypes of traction vehicles being currently drawn up are hybrid vehicles using different kinds of sources of power supply ofpower transmission systems, the most important of which are combustion engines, contact systems, supercapacitors (ultracapacitors), accumulators and fuel cells. Main engines are usually electric machines. In energy electronic starting systems it is permissible to use all kinds of main electric engines, for example, direct-current motors (inline engines, commutator motors with permanent magnets or non-commutator motors) or three-phase motors of alternating current (induction and synchronous). This means a complete change of rules in energy managing in a vehicle. Sources of energy can have the function of basic power supply (contact system, combustion engine or combustion cell) or the function of power supply support (supercapacitors, accumulators or fuel cell). New functions of drive operation will be available, namely, leveling of basic power supply load, recuperation of braking energy of the whole train set, driving at the temporary disconnection of basic power supply (short-term application of accumulator as basic power supply). Each of the above functions can contribute to the improvement of watt-hour efficiency of the system or to prolonging the range of driving. Therefore, it is necessary to undertake research on new generation power transmission systems. Research tasks focus on measurement of state variables of a drive, analyses of traction signals, modeling of drive operation in the conditions of driving cycle realization, verification of a model, drawing up a strategy of energy management in order to achieve the best watt-hour efficiency and the range of driving. In the article presented, sample results of researches on applications of hybrid power transmission systems conducted in various national research centers will be demonstrated. They concern both theoretical research (model simulation) and prototype research. The conception will be presented of a laboratory station for conducting research on modern sources of power supply and drives, which is currently being built at the Faculty of Transport of Warsaw Polytechnic at the Division of Exploitation of Tracking Systems and Electric Equipment in Transport.