Assessment of high voltage battery parameters in the hybrid electric vehicle

Abstract

The article presents the reasons why the hybrid powertrain in cars was developed. It shows how to make a better use of the internal combustion engine so that the energy in fuel be transformed into mechanical energy to the drive of a car with a greater efficiency. The article also shows the possibilities of better energy management by the recovery of the car's kinetic energy during braking and not using it during the stopover. Such an energy management requires both energy's accumulation and returning depending on the state of motion in which the car is located. The high-voltage (HV) battery is used to accumulate energy, whereas electrical machines and electronic circuits transforming electric current, are used to convert it. All elements mentioned generate energy losses. The balance of the energy's gain and losses in connection with the energy's generation and conversion is also included in the article. The HV battery plays a particular role here, as the efficiency of the entire hybrid powertrain depends on it. Therefore, the research which extended the basic diagnostic of this very important element has been carried out. The diagnostic tester enables to read some data concerning the HV battery, but they are not complete and do not allow to fully assess the condition of the HV battery. The research which has been carried out and its results extend the available diagnostic. The carried out test has concerned the battery of a 13-year-old car Toyota Prius II. The car has turned out to be efficient, and its initial capacity decreased by 18%.