Efficiency optimization of a solar boat induction motor drive

This paper describes a fuzzy logic based on-line efficiency optimization control of a solar boat drive that uses an indirect vector controlled induction motor for either speed or torque control. Besides acting on the flux level to reach optimum balance between the core and copper losses, this controller also acts upon the DC link voltage, in order to reduce the inverter losses as well. Due to its quadratic characteristics, the load torque is quite small at low to medium speeds, and the potential for energy saving is great. As the power source consists of a 48 V battery pack fed by solar panels, a boost converter is controlled to yield just the voltage level required for proper current control, at partial speeds, resulting in additional efficiency improvements. An experimental drive system with the proposed controller implemented on a TMS320C25 DSP based control board was next constructed and tested in a laboratory to validate the proposed technique.