In view of demerits of existing power supply topological structure for UHV tests

we proposed a topological structure of power supply for cascaded multi-level FM resonance extra-high voltage tests and its control method. In order to reduce the total distortion rate of output voltage

the traditional single-level AC/AC converter was replaced by the carrier phase shifting-based back-to-back cascaded multi-level converter to constitute the high-power frequency and pressure-modulation signal source. Firstly

we studied the mathematical model of rectification system and its double-closed-loop control strategy

and introduced a balance strategy for the capacitor voltage. Then

we studied the mathematical model of boosting part of inverter

proposed the multi-loop control strategy

and performed the stability analysis on the improved topological structure and its control method. Taking a cascaded five-level converter as an example

we conducted system simulation on the improved test power supply on the PSIM platform taking 10 kV high-pressure AC as input voltage. The simulation results show that the method can successfully be used to lower the total distortion rate of output voltage of high-power frequency-pressure-modulation signal source

and the transformation ratio

volume and weight of transformer can be reduced

thereby improving the system efficiency.