Such converter allows the current flow in both directions:
from the battery to the motor when the electrical motor is
working as a motor; from motor to the battery, when it is
working as a generator. In the motor mode, as mentioned
above, the main condition to obtain the motor assistance is
that the cyclist is pedaling in the forward direction. The
converter, in the step-down mode, assures a constant link
voltage value for sourcing the inverter. It has to keep the link
voltage independent from the battery output voltage (V
d
)
which is connected with its state of charge. Fig. 7 shows a
scheme for the step-down converter.