DSP based Pre-Processed PWM scheme for 3-Limb core coupled inductor inverters

Performance of a power electronic system is identified with its system efficiency, system cost, and the devices being used. This work illustrates how a Digital Signal Processor (DSP) based Pulse Width Modulation (PWM) switching scheme can be used as a low cost control solution to provide better excitation for the magnetic core of a 3-Limb Core Coupled Inductor Inverter (CII). A modified version of interleaved discontinuous PWM scheme with two carrier signals is conceptually chosen to keep the flux to the magnetic core. The PWM switching patterns are chosen to guarantee that all the inverter switching states maintain a zero inductor net winding voltage for the three phases. In a practical sense, this requires extensive control and modulation tasks which calls for a high-end processor with parallel and post processing capacities. A less complex solution, by manipulating the original conceptual scheme, is introduced as an alternative Pre-Processed scheme for a DSP environment using only one carrier signal. Experimental results verify that the DSP PWM module can successfully implement the target PWM scheme. The DSP realization of the PWM scheme not only provides cost effectiveness by eliminating the need for a high-end processor, but also minimizes the size of the control circuitry. Experimental results confirm that the DSP based scheme offers efficiency enhancements expected from the original conceptual scheme due to benefits related to the reduction of the high-frequency winding current ripple.