Gyuláné Vincze, Gergely György Balázs
Budapest University of Technology and Economics Department of Electric Power Engineering
Motive and brake force are opposite, as can be seen in Figure 1.6. In the figure it is not indicated, but most vehicles has to be able to move forward and backward. Operational modes needed for traction can be seen in Figure 1.7.
In I and III quadrant of a general 4/4 quadrant mode, the motive power is P=Fv>0, in this case drive operates as a motor. In II and IV quadrants P=Fv<0, in this case drive operates in brake mode. Modern vehicle drives can change between quadrants without mechanical or electric switches, i.e. drive is also 4/4 quadrant. There are drives suitable only for less quadrants. For example, internal combustion engines can operate only in one quadrant, forward and backward reversal has to be done mechanically and brake is realized only mechanically, except power brake.