Current Transformer-Based Power Supply for Pulse Encoders on Motor Power Lines in Adjustable Speed Drive Systems

This paper proposes a novel power supply system for an encoder in motor drive systems. The proposed system eliminates the need for a dedicated power supply cable for the encoder by utilizing a current transformer connected to the load motor. A design method for the current transformer is presented, considering its operation under non-linear loads and variable frequencies. The design process is simplified by modeling the diode rectifier as an equivalent voltage source. The validity of the proposed design is verified through experiments, demonstrating that the output voltage closely matches the design values. Additionally, a DC- DC converter is implemented at the output side of the diode rectifier to stabilize the output voltage. Experimental results confirm voltage stabilization across the entire operating range on the N-T map.