Offline optimized pulse pattern with a view to reducing DC-link capacitor application to a starter generator

In an embedded application, electrical equipments are connected to the onboard network. In order to avoid any dysfunction, the DC-link voltage has to be as constant as possible. To achieve this purpose, a high capacitance is inserted in parallel to the network. This paper shows relationship between DC-link voltage ripple and DC-link current ripple by using a simplified equivalent scheme of the onboard network. Control of the DC-link current permits a reduction in the capacitor's size without increasing significantly the DC-link voltage ripple. An optimal pulse width modulation (PWM) strategy is proposed to control DC-link current harmonics. The general equation system and the numerical computation of simple examples are developed in this paper. A starter generator application embedded in an automotive vehicle is used to illustrate our work.