Current Loop Bandwidth Extension for AC Servo System Based on GaN-HEMT and FPGA

In order to increase the productivity of the manufacturing process, a servo system with high bandwidth current loop should be realized. Switching frequency and digital delay are the main factors affecting the bandwidth of current controller. This paper focuses on the design of Gallium Nitride (GaN)semiconductors based AC servo drive system, one of its aims is to increase switching frequency. The field-programmable gate array (FPGA)is used, multiple stator current sampling and multiple PWM duty cycle update (MSMU)in a carrier period is proposed to reduce digital delay. Experiments on 100 kHz switching frequency show that the current control loop bandwidth can be extended to 6 kHz.