Abstract
The stability of energy optimal control (EOC) when the hybrid electric vehicle performs self-driving with speed control is verified by simulation and numerical calculation. As for the effects of the dead time of acceleration and velocity feedback, simulation that add dead time stepwise to both feedback results in negligible control error even if the dead time up to 40 ms (equivalent to 4 cycles of control loop) is given. As for the convergence of control, since the necessary and sufficient condition for the solution of the Euler-Poisson equation gives the minimum value of the evaluation function is that the second variation of the evaluation function is positive, the second variation of the evaluation function for both control law of engine and motor are calculated. As a result, it was shown that the engine control law is positive over the whole operation area on the torque-angular velocity plane, and it is the optimum solution over the whole operation area. Regarding the motor control law, although a part of the locus passes through the negative region, most of it exist within the positive region, indicating that the motor operated generally under the condition that the evaluation function had a minimum value.
