Traditional controllers such as PI, PR, and DB rely on real-time feedback loops. However, due to the control delay in the system, the feedback signal cannot immediately track the reference signal, resulting in overshoot even if the parameter adjustment is ideal. Therefore, if a controller that does not require instantaneous feedback of the target signal can be found, when the reference signal changes, this controller can immediately output a control law to solve the overshoot caused by closed-loop feedback, which is conducive to improving the dynamic characteristics of grid-connected inverters. In this paper, based on the vector relationship between the physical quantities of the energy storage elements in the voltage source inverter, an ideal differential controller that does not require feedback is proposed, and this controller is realized based on a step-combined excitation voltage mode. The step-combined controller consists of Proportional-Proportional-Delay (PPD), so it is named the PPD controller. The PPD controller parameters are designed using methods such as step excitation current response, differential-integral transformation, and error approximation. Then, the dynamic characteristics, universality, and robustness of the PPD controller are analyzed, and a series of measures are proposed to improve the practicality of the PPD controller.