Development of Compact Rapid Capacitor Charging Power Supply for TMS

To improve the stimulation efficiency of transcranial magnetic stimulation (TMS) and reduce the size and power consumption of the overall circuit, a compact and efficient capacitor charging power supply using an inductor-capacitor-inductor-capacitor resonant converter (LC-LC RC) is designed in this study. The LC-LC RC has the characteristics of low power consumption, high efficiency and uses the voltage gain of the resonant circuit itself and a voltage doubler rectifier circuit instead of the transformer to reduce the size and weight of the overall circuit. A detailed ac analysis with fundamental frequency approximation of the LC-LC RC is presented. Expressions for converter gain, operating condition of the converter as a constant-current power supply, and condition of the converter voltage and current zero-phase difference are derived. In addition, RC design value conditions for the minimum resonant network size are derived. An experimental 1.05 A 120 V prototype converter is designed, developed, and tested to verify the theoretical analysis. Experimental results indicate that this circuit is suitable for use in capacitor charging to increase the stimulation performance of TMS.