FPGA-based hardware-in-the-loop simulator of high switching frequency power converters

To take advantage of volatile renewable energy, implementation of digital control is effective since it supports the application of various advanced control theory and communication functions. However, it is usually difficult to use the actual plant to be controlled at the control software development stage, particularly in terms of cost and safety. Therefore, during the control software development phase, it is expected to substitute a Hardware-in-the-Loop (HIL-simulator) so that the controller hardware can be placed in the feedback control loop for the actual plant. The development of HIL-simulators for the switching converter has been recognized to be a challenge because of the high control frequencies involved. However, it is possible to realize a HIL-simulator using a partial variable step method that is able to compute switching behavior in a precise manner and with state space equations that help minimize the calculation time required for the execution of the aforementioned method. This technique can also be applied to slower computational devices such as microprocessors. However, using FPGA, it is possible to develop a more realistic simulator with minimal computational delay. This study describes a HIL-simulator that simulates the electrical circuit of the switching converter that is able to provide 0.1% duty ratio resolution at a 100 kHz switching frequency.