Analysis and design of a current transformer fed power supply from high AC voltage cable

In this paper, a current transformer fed power solution from the high voltage cable is proposed to effectively provide energy to the wireless sensors or other monitor equipments. The equivalent circuit model of the inductive power supply is built and analyzed to optimize the power delivery capability and extend the life span of the magnetic core. Then, the relationship among current transformer´s output power, output voltage, load condition, magnetic core parameter and coil turns are derived to give a design guidance for the proposed solution. Furthermore, a practical power supply circuit with a two-stage converter configuration is proposed to achieve the power transmission. The first stage adopts the hysteresis controlled Boost pre-regulation circuit to get large output power and prevent core saturation as well. Buck circuit is employed as the secondary stage to get the required supply voltage. Finally, the output power of the current transformer and the power supply system with 15V/18W DC output from the 200~1000A current loop is tested to verify the effectiveness of the theoretical derivation.