A 115V bi-phasic pulse electrical muscle stimulator by using inductor-sharing dual-output boost converter with supply-stepping switch driver

This paper presents an approach of sharing one inductor to generate dual-output boost converter circuit with supply-stepping switch driver circuit in order to generate biphasic pulse in Electrical Muscle Stimulation (EMS) application. The inductor-sharing dual-output boost converter in this paper is an approach that shares one inductor in both positive path and negative path of the boost converter. The proposed circuit can provide dual high supply voltages at stimulator output by using only one inductor. In order to perform EMS function, supply-stepping switch driver circuit is introduced. The presented supply-stepping switch driver is composed of two resistor-based inverters which has different level of supply voltage. Also, comparator-based voltage limiter circuit is added for limiting output voltage of the proposed boost converter to prevent overboosted voltage due to discontinuous mode of boost converter operation. The experimental result shows that the proposed converter can achieve dual boosted output voltage and the simulation result confirms that the proposed circuit can generates bi-phasic symmetry voltage pulse of +/-115V driving a resistive load of 1kΩ under supply voltage of 9V.