Modified Digital Current Controller for High Precision Electric Motor Emulators

The electric motor emulator (EME) represents a practical application of power hardware-in-the-loop (PHIL) technology, facilitating the testing of electric motor drive units (MDUs). Its main function is to replicate both the steady-state and dynamic current characteristics of electric motors. Typically, the current loop in the EME functions as the inner loop of that in the MDU, requiring a high control bandwidth to ensure superior dynamic response performance. This paper analyzes the limitations of the control strategy for the EME introduced in a recent study and proposes a modified digital complex vector controller (MDCVC) with better dynamic performance and enhanced disturbance rejection capability. First, an internal loop is introduced to replace the complex poles of the original platform with real poles, followed by the design of a current controller to achieve overshoot-free current tracking performance. Furthermore, to improve the disturbance suppression performance, an additional active damping term is incorporated into the control loop. As a result, the dynamic characteristics of the target electric motor are accurately reproduced. Comparative evaluation tests are carried out to validate the effectiveness of the proposed control scheme under various operating conditions.