Generating High Switching Frequency by Integration of FPGA with DSP Using SPI

Power electronic converters are essential for energy conversion, and advancements in wide bandgap devices like SiC MOSFETs and GaN HEMTs have enabled use of higher switching frequencies. Sophisticated control method of power electronic converters increasingly require digital platforms like DSPs and FPGAs for implementation. However, when only DSPs are used, they are limited to switching frequencies of around 50 kHz. In contrast, FPGAs support higher switching frequencies but are costly due to the need for large number of logic gates for complex algorithms. This paper proposes a hybrid approach in which control methods are implemented on DSP, and high-frequency PWM generation is implemented on inexpensive FPGA. Serial peripheral interface (SPI) protocol for communication between DSP and FPGA is used. Existing literature does not provide clear methods for such hybrid implementation. Proposed approach reduces the need for expensive FPGAs and utilizes the computational power of DSP to maximum. The proposed method is experimentally verified by controlling a DC-DC converter at a high switching frequency.