Modulation-based Selective Harmonic Elimination For DC-to-AC Inverters

Open Access
Chen, Jeffrey
Area of Honors:
Electrical Engineering
Bachelor of Science
Document Type:
Thesis Supervisors:
  • Jeffrey Scott Mayer, Thesis Supervisor
  • John Douglas Mitchell, Honors Advisor
  • power electronics
  • pwm
  • spwm
  • she
  • harmonic elimination
  • harmonics
Selective harmonic elimination (SHE) is a method of generating pulse width modulated (PWM) signals that do not include low-order harmonics. It is well suited for high power dc-to-ac inverters that must operate at low switching frequencies due to limitations associated with the switching devices. While the development of higher speed switching devices had relegated this method to a small niche, a recent surge in digital implementation of dc-to-ac inverter controllers has spurred renewed interest in the method. The implementation of conventional SHE, particularly in real-time applications, remains challenging due to the need to solve a set of transcendental equations for the switching angles of the PWM signal. In a 2007 paper, a method that combines SHE with direct modulation was proposed. This method is referred to as modulation-based harmonic elimination (MBHE). It offers the possibility of having the advantages of SHE in terms of eliminating low-order harmonics and the advantages of direct modulation in terms of relative ease of implementation. This thesis project aims to replicate and evaluate MBHE. The method has been implemented on an Arduino microprocessor as a proof of concept. The output of the circuit is evaluated for low-order harmonics for a number of different input parameters.