FPGA-Based Implementation of a Predictive Current Controller for Power Converters

Predictive control is generating considerable interest when it comes to implementing current control strategies in power converters. Remarkable accuracy and fast dynamic response are its main characteristics. However, this technique is computationally demanding compared to classic control schemes. This is particularly true in multilevel converters, where several variables of the system such as currents, switching frequency and neutral-point voltage balancing, to name a few, are controlled simultaneously. An important issue is to reduce the delay between the variable sampling and the instant at which the switching state is applied to the converter. Although DSP-based implementations have been proven to be an effective solution, the parallel nature of predictive controllers better fits with the architecture of field-programmable gate array (FPGA) devices. This paper presents a new approach to the FPGA-based implementation of a predictive current controller for a multilevel converter. This approach also aims to reduce the average switching frequency and obtain neutral-point voltage balancing. The switching state is applied in the same sampling period in which the controlled variables are measured thereby enhancing the dynamic response of the system.