Switching time model updating for the real-time simulation of power-electronic circuits and motor drives

The main hurdle in achieving real-time performance for the simulation of power-electronic circuits is the large calculation effort required to update the model after a discontinuous change in switch impedance. The method presented here suggests that by separating the switch model from the rest of the circuit, only a much smaller equation set needs updating. Thus, it reduces the update effort to a level where it is no longer the bottleneck of the overall simulation loop. Unlike previous works on this issue, the method is independent on both the simulation approach and the circuit topology. The method has been tested on a variety of circuits with impressive results, two of which are presented here. First, there is a complete HVdc system, representing the higher limit in size and complexity. Second, a pulse-width-modulated motor drive with an external controller in a hardware-in-the-loop configuration represents a higher limit in performance requirements. Both test circuits are simulated in real time on a low-cost off-the-shelf personal computer, using the xPC technology from Simulink and automatic generation of optimized code, and are compared to a very precise variable step offline simulation.