Minimizing DC capacitor current ripple and DC capacitance requirement of the HEV converter/inverter systems

This paper presents an accurate theory of calculating the DC link capacitor voltage ripples (Ampere-Second) and current ripples (Irms) for inverters and PWM rectifiers, which are most commonly used in hybrid electric vehicle (HEV) converter/inverter systems. The results are analyzed and summarized into graphs according to the theory, which helps to find the right capacitance value for a given voltage ripple tolerance and the rms ripple current that the capacitor has to absorb. The comparison shows that the calculation result and experimental result are in close agreement. Therefore, these theoretical calculation results help to minimize the DC capacitors rather than merely relying on simulation methods.