Generalized selective harmonic control

Selective harmonic elimination/control is a widely researched alternative to traditional PWM techniques. Previous work made fundamental assumptions that enforce quarter-wave symmetry, presumably in order to reduce the complexity of the resulting equations. This assumption is not required, and it restricts the solution space, which could result in suboptimal solutions with regard to the uncontrolled harmonic distribution. More general formulations can be proposed which have varying degrees of additional complexity.; The first section of this dissertation describes a generalized selective harmonic control (GSHC) problem by first relaxing the quarter-wave symmetric restriction to a half-wave symmetric restriction. This half-wave symmetric problem is examined in detail with a focus on two-level waveforms. Next, the half-wave symmetric restriction is removed and the resulting GSHC problem is again examined with a focus on two-level waveforms. Although two-level waveforms are described extensively, both relaxations can be applied to the m-level, n-harmonic control problem which is also discussed. Analysis of the harmonic spectrum sensitivity to errors in the placement of switching edges is presented to assess the practicality of new solutions that can have very narrow pulse widths.; The generalization presented here results in sets of solutions that bear a distinct resemblance to traditional PWM methods. The next section of the dissertation explores this relationship between GSHC and traditional PWM. A modulation design process is detailed, illustrating how a series of GSHC solutions can be used to develop a modulation process for obtaining GSHC solutions with varying numbers of harmonics controlled. This design process is applied to typical cases encountered in SHC applications including waveforms where all harmonics are controlled and those where triplen harmonics are left uncontrolled.; In the final section of the dissertation, performance aspects of GSHC are examined within the limitations of the current ability to obtain solutions. Relative performance of an available set of solutions is compared, illustrating the importance of selecting a particular solution over another. Additionally, the potential for improved EMI performance by solutions which reduce strong peaks in the energy related to the switching frequency of the waveform is examined.