Mechanical and electrical system control conventionally uses the Lagrange motion equation for general mechanical and electrical motions. However, using the Lagrange approach for the control system is difficult to understand physically and intuitively. This paper proposes estimation and control methods for the reaction energy of a mechanical synchronous motor and an electrical LR circuit. The reaction energy is the inflow energy from outside the actuator; it is estimated and controlled by the newly defined energy disturbance observer and reaction energy observer. A generalized Heaviside operator is also introduced to simplify the representation of the energy control system. The effectiveness of the proposed methods was verified by simulation of a mechanical synchronous motor and an electrical LR circuit.
