DSP control of 400 Hz inverters for aircraft applications

This paper presents a fully digital control method that can be used for inverters used in 400 Hz aircraft ground power units. The method presents an ideal tracking controller that incorporates the computational delay as well as the quantization effects. It uses an observer for the output current third, fifth and seventh harmonics in order to achieve decoupling between the voltage and current loops thus leading to a low THD content in presence of non-linear loads The implementation of the observer is reduced to IIR filters with normal architecture that have minimum round off errors. The control method is implemented on a 16-bit single chip DSP-based controller from Analog Devices (ADMC401) and tested on a single-phase 10 kVA IGBT-based inverter prototype showing almost complete elimination of the third, fifth and seventh harmonics from the output voltage.