Stretch Meat Grinder: A Novel Circuit Topology for Reducing Opening Switch Voltage Stress

Abstract

The slow transfer of energy through capacitive hybrid (STRETCH) meat grinder is an inductive- capacitive current multiplication circuit that reduces switching requirements and achieves a high degree of current multiplication while possessing an energy density approaching that of a purely inductive system. Initially, the STRETCH meat grinder operates like a single-stage meat grinder; it increases the current through an inductor by switching out a coupled inductor. However, during switching in generic meat grinder circuits, leakage flux caused by imperfect coupling and the sudden change in current induces a voltage across the opening switch well beyond what modern solid-state switches can handle. The STRETCH meat grinder mitigates these problems by using a capacitor to recapture the energy in the leakage flux and to slow down the turnoff of current in one of the inductors. The energy from the leakage flux is then used to reverse the current on the turned-off inductor, thereby further increasing the current multiplication. A system comprising several STRETCH meat grinders in parallel can develop currents in the mega-ampere range without exceeding the capabilities of solid-state switches. Such a system could be used to power a railgun.