Operation of electric hybrid drive systems in varied driving conditions

The variety of hybrid drives available from most passenger vehicles manufacturers means that the interest in the energy flow in such vehicles is very high. Vehicle hybrid drives have been dominated by parallel drives with independent internal combustion engine or electric motor propulsion. Parallel systems with the electric motor supporting the internal combustion engine – despite their simpler construction – are much less common. This is due to the less universal nature of such a hybrid drive solution in everyday urban and non-urban traffic [5]. Tests of vehicles powered with alternative fuels or with alternative propulsion systems are carried out with respect to their respective harmful components emissions [6, 8, 9]. Increasingly more often, these studies refer to conditions of energy flow in hybrid [12] or electrical systems [3]. The theoretical and road analysis of the increased energy recovery potential through the use of different gearing reduction strategies is described in [4]. There are currently many models of hybrid drive systems [1, 2, 11, 13], but road tests of such systems are the basis for the verification of simulation test results. Current hybrid drive solutions, despite the use of batteries with rated voltages between 200 V and 250 V, allow the electric motors to operate on up to 650 volts. This input voltage gain allows for a 2.5 to 3 times increase in the nominal voltage. Voltage converters are described in [7, 10], among others. Previous studies have not dealt with the issue of the effect of changes in the electric motor supply voltage to its operating conditions. Taking this into account, the authors have divided the voltage boost value into several compartments: U a) < 300 V, 300 V b) ≤ U < 400 V, 400 V c) ≤ U < 500 V, 500 V d) ≤ U < 600 V, U e) ≥ 600 V.