Analysis of a low power, high voltage and high gain capacitor charger with output sourcing behavior

Abstract

This study presents a novel, triangular current shaped, low power, low input and high output capacitor charger with current sourcing characteristics. Unlike the Flyback topology, which is commonly used for high voltage low power chargers, high leakage of the isolation transformer is allowed here. Consequently, the primary and the secondary windings need not be kept close to each other, and the transformer can be wound on a bobbin with several sections. This way, the primary and the secondary sides are isolated by the bobbin fins. Moreover, the secondary winding can be spread over a number of sub-sections. This is advantageous in applications where high voltage, developed between the primary and the secondary sides of the transformer, as well as between the windings of the secondary side itself, can lead to electrical breakdown. A theoretical analysis is verified by simulations and experiments on a 2.5kV capacitor charger which is fed from a low voltage source. The analytical considerations and experimental results show that the proposed charger is an excellent engineering choice for low power high gain and high voltage applications.