This selective harmonic current mitigation pulse width modulation (SHCM-PWM) and phase-shifted pulse width modulation (PSPWM) hybrid increases the efficiency of converters during steady-state and transient conditions. This hybrid modulation is advantageous when using DC to DC power converters, which are used in many electronic devices, such as cell phones, laptops, or charging stations, and it can also maximize the energy harvest for photovoltaic systems and wind turbines. Both SHCM-PWM and PSPWM are used separately now, but each exhibits individual problems with modulation. SHCM-PWM has poor dynamic performance, due to a low number of switching transitions, and often has an inadequate power range. PSPWM has low efficiency because it requires high switching frequencies and requires passive filters to meet the power quality requirements. Researchers at the University of Florida have developed a SHCM-PWM and PSPWM hybrid that alternates between the two modulations depending on whether the system is in steady-state or transient conditions.
Hybrid current modulation system that increases the efficiency of four-quadrant, grid-tied converters for use in electronics such as electrical vehicle charging stations, renewable energy harvesting, or HVDC and PET applications
This hybrid modulation technique combines SHCM-PWM and PSPWM to achieve high dynamic performance for four-quadrant grid-tied converters. This hybrid uses SHCM-PWM under steady-state and PSPWM under transient conditions. During steady state conditions SHCM-PWM increases the efficiency of the system, while PSPWM updates switching transitions several times in each fundamental cycle to achieve high dynamic response performance under transient conditions. A specifically designed controller switches between these two modulations. In order to process four-quadrant active and reactive power, the modulation index range of SHCM-PWM greatly extends by modifying the constraints of switching angles. The lowest number of switching transitions for PSPWM prevents a reduction in efficiency and performance of the indirect controller.