| The paper deals with MATLAB simulations of the regenerative braking for an electrical scooter. Various modern possibilities to achieve regenerative braking at light electric vehicles are approached firstly. Afterward one presents aspects of the original simulations related to a scooter equipped with a single-stage bidirectional DC/AC converter based on a general full-bridge inverter in order to implement regenerative braking. The simulator relies on a model from the SIMULINK library, which represents a synchronous motor with permanent magnet and trapezoidal excitation. Other major components of the simulator are: a model of converter with three-phase bridge, realized with MOSFET transistors and anti-parallel diodes; a logical model of the control circuits for the transistors placed on the bridge’s arms in order to make the motor to advance, respectively to cause its braking. Two modules were conceived to test the current drawn (or injected) from (or toward) the source during scooter’s advance (or brake), respectively to test the consumed (or recovered) energy. The paper includes the simulated waveforms corresponding to various quantities, at the beginning or ending of the braking process, considering a filling factor of 70%. Other simulations were performed with a variable filling factor, in order to evaluate the recovered energy when the speed was reduced from 45 km/h up to 20 km/h. Considering the variation of the recovered energy with the filling factor, the simulations revealed an increase of this energy up to a certain value when the factor is increased at the beginning of the variation range, followed by the recovered energy decrease for higher values of this factor. The phenomena responsible for these variations are discussed. For the studied scooter, the reducing of speed from 45 km/h up to 20 km/h is reflected in a maximum recovered energy of 35% from the total energy stored as kinetic energy by the moving scooter with a maximum weight, respectively 43% from difference between the scooter’s initial and final kinetic energies respectively. |
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