Investigation of Charge-Rate Increase for a Capacitor Charging Power Supply in Burst Mode Operation

Interest in rep-rate operation of pulsed power systems has led to an increase in power requirements of high voltage (HV) capacitor charging power supplies (CCPS). Compact repetitive pulse power systems provide an impetus to develop supplies with a high power density (HPD). We have an application requiring compact HPD CCPS´s and have evaluated a number of options to determine their applicability to a bipolar charging scheme with a charge rate requirement of 6400 J/s. The load for our application has significantly imbalanced charge rail stray capacitances, which introduces issues with CCPS polarity dominance and no commercially available options were found to be satisfactory. This paper discusses our effort to modify a commercial CCPS to meet our requirements for charge rate and control versatility. Two Lambda Americas model 152A CCPS, of opposite polarities, were modified to operate from DC prime power and used to charge a bench load capacitance with integrated diagnostics. The primary objective was to double the effective rating of the commercial supply in a low duty cycle burst mode through modification of the operating parameters. The impact of variable switching frequency, passive resonant component value, and prime power voltage level on the charge rate is examined in detail. Burst-mode charge rate increases of greater than three times the continuous rating are reported. The impact on efficiency and reliability of the supply after modifications is also discussed.