PWM of a modular inductive storage millisecond pulse-forming network

Millisecond pulse-forming networks are used to generate an energy pulse of up to several Megajoules in a defined pulse shape and time span. Passive pulse-shaping methods are often used. An alternative is to use switches to commutate energy from a storage medium into the load. The type of storage medium and the power levels used define the switch type. For capacitive storage, one requires a turn-on switch, for inductive storage, a turn-off switch is required, and for battery storage, a turn-on/turn-off switch is generally required. Such a system usually requires a staged energy transfer. In order to shape the pulse, either a final pulse-shaping stage can be included in the system or a modular system can be employed. This paper discusses the use of PWM to approximate the pulse shape as required. This allows the reduction of the number of modules and greater control over the discharge pulse shape. Results using a two-module system are presented and a comparison is made to a four-module system not using PWM.