A desktop electric machine emulator implementation method based on phase voltage reconstruction

An electric machine emulator (EME) system plays a fundamental role in design and validation of hardware and software for power electronic converters and electric drives. In this paper, a desktop digital signal processor (DSP)-based EME is developed for power converters function test. The principle of EME is demonstrated with mathematical derivation. Since the instantaneous phase voltage is either power supply voltage or ground, high-rated voltage sensors are not suitable for DSP-based EME to obtain the average voltage in a pulse-width modulation cycle. To accurately acquiring phase voltages, a method which reconstructs the phase voltage considering the amplitude and duty cycle error is proposed. Voltage drops, dead time, propagation delay, parasitic rising and falling time delay are all considered in reconstructed voltages based on voltage-second balance theory. This is accomplished without any assistant physical circuits. Based on the reconstructed phase voltages, reference current is derived in motor model by using second order Runge-Kutta method. Factors affecting phase voltage accuracy are verified by simulations step by step. The simulation and experimental results support the validity of the proposed method.