The objectivity and validity of dynamics test for power-train is guaranteed by emulating the mechanical inertia accurately. The control method is the key to inertia electrical emulation. According to the dynamic model for dynamometer with angular acceleration control method and torque control method

the equivalent inertia is defined according to the physical define of the moment of inertia. Furthermore

the equivalent inertia is adopted as the criterion of evaluating the control method of electrical emulation system. The equivalent inertia is analyzed in frequency domain. The results show that the emulation precision and response speed of angular acceleration control method are prior to torque control method under the same characteristics of dynamometer motor as well as its driving control system. The signal delay has a significant influence on precision and response speed of inertia electrical emulation

and the torque control method is more sensitive to delay.