Pulse step modulation (PSM) high-voltage power supply is widely used in the heating systems of the Experimental Advanced Superconducting Tokamak (EAST). This power supply adopts a modular topology, where the high output voltage is generated by superimposing the outputs of multiple independent DC power modules. In conventional designs, input over-voltage and under-voltage protection for each power module is achieved by installing individual voltage sensors across the input capacitors.

However, this method requires a large number of voltage sensors, which significantly increases system monitoring costs and complicates the hardware detection circuitry. To address these limitations, this study aims to develop a sensorless voltage measurement (SVM) method capable of estimating the input voltage of each power module using only a single voltage sensor on the output side.

This paper first introduces the circuit topology of the PSM high-voltage power supply and provides a detailed analysis of its control strategy. Building on this foundation, a novel sensorless voltage detection technique is proposed to estimate the input voltage of each power module. The method utilizes only one voltage sensor installed at the output side of the PSM high-voltage power supply to collect voltage signals, from which the input voltages of individual modules are derived through algorithmic processing.

To validate the proposed method, a model was constructed and tested based on the RT-LAB real-time simulation platform. Experimental results demonstrate that the SVM technique can effectively estimate input voltages, thereby confirming the feasibility of the proposed method.

The study concludes that the SVM method not only reduces the number of required sensors and associated costs but also simplifies the system architecture while maintaining reliable module-level voltage monitoring. The findings provide valuable insights for the design of modular power supplies in large-scale experimental setups and suggest potential applications in other multi-module power electronic systems.