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The main physical parameters in case of traction vehicle design are: Maximal desired velocity, desired traction power and traction torque on vehicle velocity dependence. In case of electrically driven vehicles these requirements are solved by the variable parameters of electric energy for motor supply. Power required for motor terminals in accordance with vehicle speed are for comparable vehicles the same. In case of electric drive, the power, needed for motor supplying could have different parameters, characterized by the supply voltage, current and its frequency. Supply voltage and current frequency must be proportional to vehicle required speed of course. But torque creation is very sensitive on air gap magnetic field revolutions and machine rotor revolutions difference. This difference is characterized by the rotor current frequency (f2) or by the corresponding rotor current angular velocity ω2 = 2π f2. Operational regime of AC induction motor is characterized by three independent parameters: Stator voltage U1, stator voltage frequency f1 and rotor current frequency f2. These parameters determinates torque T, stator current I1 and its relation T/I1 unequivocally. Electrically driven vehicles enable to recuperate electric energy during braking interval. It is very temptingly to recuperate braking energy with maximal efficiency when relation I/T achieved its maximum for desired braking torque. To solve this problem is possible theoretically in case, if basic motor parameters – winding inductance and resistivity are constant parameters. But in real case resistivity changes with temperature and inductance depends on current. Therefore, in real case of this troubleshooting is based on theory and experiments combination. In case of induction machine working regime optimization it is necessary to split the task on the motor and generator regimes. In case of electric vehicle recuperation braking, it is convenient to achieve for desired braking torque maximal active current for electric accumulator charging. From theory and previous experiments imply that it exists I/T relation maximum like in motor so in generator regimes. Optimization of motor regime were analysed and experimentally verified in L/1/. The case of recuperation regime is analysed in this article.
Prof. Pavel Mindl, Czech Technical University in Prague FEE, CZECH REPUBLIC Prof. Zdeněk Čeřovský, Czech Technical University in Prague FEE, CZECH REPUBLIC Dr.-Ing. Pavel Mňuk, Czech Technical University in Prague FEE, CZECH REPUBLIC
Optimization of induction machine generator regime in electro mobile
F2020-ADM-099 • Paper + Video • FISITA World Congress 2021 • ADM - Advanced Vehicle Driveline and Energy Management
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