Modeling and control of boost converters with application to energy harvesting

In this thesis, we investigate the development of new control schemes for single- and three-phase boost-type converters and their application to energy conversion. The developed algorithms are utilized to efficiently convert energy from a source with an arbitrary voltage waveform to a DC link or a battery. This type of energy transfer is of great interest in energy conversion systems involving low frequency, time-varying input sources such as vibration energy harvesting and marine wave power. In such applications, the generated voltages are sporadic in the sense that the amplitudes and frequencies of the generated waveforms are time-varying and not known a-priori. Motivated by these applications, first a single-phase boost converter is studied and the performance of the proposed controller in providing a resistive input behavior is experimentally verified. Next, the idea proposed for a single-phase converter is extended to a three-phase bridgeless boost-type converter. To this end, an averaged model of the three-phase converter is obtained and utilized in designing a feedback control scheme to enforce a resistive behavior across each phase of the converter. Similar to the single-phase system, the proposed controller does not require a-priori knowledge of the input waveform characteristics and can convert waveforms with time-varying frequencies and amplitudes into DC power by regulating the input resistances at each phase. The proposed solution enables real-time variation of the generator loading using high efficiency switching power devices. Numerical simulations and experimental results are presented that evaluate performance of the proposed modeling and feedback control scheme for the three-phase system. Finally, an application involving energy regeneration for a mechanical suspension system is considered using a setup consisting of a mass-spring test rig attached to a mechanical shaker for single- and three-phase applications using a tubular DC permanent-magnet machine and rotary machine connected to an algebraic screw, respectively. The algebraic screw converts the translational motion of mechanical vibrations into rotary motion that acts as a prime mover for the three-phase synchronous machine. The experimental results reveal that the boost circuit and proposed feedback controller can successfully provide regenerative damping for mechanical vibrations with high-efficiency power conversion.