An AC Drive System with Flexible Driving Modes Applied in Ship Power Station

This paper designed a special ac drive system which could realize directly or softly starting up ac motors. This ac drive system is consisted with boost converter and 3-phase inverter, it could operate either from rectifier utility power or battery packs. The duty cycle forward control is adopted in boost control loop to assure the stability of the output dc bus voltage under the disturbance of input voltage. SVPWM is used in 3-phase inverter to improve the utilization ratio of dc bus voltage and the waveform factor of the output ac voltage. To keep the output ac voltage stability under the disturbance of load and save the compute time of the software simultaneously, a closed output voltage control loop is used after the frequency reach the rated value. This ac drive system is applied in ship power station to drive the ac motors which dragging the ac electric oil pumps of electric power generation unit. It can directly start up 1.5kW, 380V/50Hz ac motor or softly start up 3kW, 380V/50Hz ac motor with constant V/F under flexible input voltages (rectifier utility power or battery packs). The test results show that the designed ac drive system has robust performance with the disturbance of input voltage and loads.