An Analog Optimum Torque Control IC for a 200-W Wind Energy Harvesting System

An optimum torque (OT) control integrated circuit (IC) is implemented for harvesting the most available energy from a wind turbine generator (WTG) in a wind energy harvesting (WEH) system. For maximum power point tracking (MPPT), a rotor speed detector is proposed to obtain the root-mean-square (RMS) value of the WTG output voltage, which is proportional to the rotor speed. Then, three-phase current references are generated by multiplying the RMS value with the three-phase WTG output voltages for regulating the three-phase WTG output currents to achieve OT control. Further, a background calibration circuit is also implemented for adjusting the OT trajectory to maintain high MPPT efficiency. Moreover, to achieve a high power factor and low total current harmonic distortion (THDi), this brief applies three-phase carrier-based current sinusoidal PWM to drive a fully controlled boost rectifier. The chip is fabricated in 0.5-μm CMOS process with a 0.35-mm
²
chip area and measured with a WTG test rig designed to emulate the electrical output of a WTG. Measurement shows the proposed IC with fully controlled boost rectifier achieves 96.1% peak power conversion efficiency, 0.99 power factor, and 1.7% minimum THDi based on a 200-W WEH system. Compared with prior IC-implemented state-of-the-arts, this brief featuring welldesigned circuit linearity has superior power conversion efficiency and THDi.