Due to the limited operation mode

a large number of power electronic devices in the high voltage direct current（HVDC） circuit breaker are unable to be powered by the system

which is one of the main difficulties in the development of the HVDC circuit breaker. Based on the load characteristics of insulated gate bipolar transistor（IGBT） driving boards in 500 kV HVDC circuit breaker

this paper presents a layer-isolated power supply scheme including layer to ground

layer to layer

and single component. The multi physical field simulation research of electromagnetic field

mechanical field and thermal field of the ground-isolated power supply transformer is carried out

and the power supply coil of the IGBT driving board at high potentials is designed. The simulation model of the power supply coil and the load is built through the finite element simulation module Maxwell and the circuit simulation module Simplorer

and the field-circuit coupling simulation is conducted. Finally

the feasibility and reliability of the proposed scheme are verified by the tests on a 500 kV HVDC circuit breaker. The results show that the isolated power supply can provide stable input current for power supply coils in each layer

so as to reliably provide power for driving boards of power electronic devices at high potentials. The proposed model not only solves the problem that HVDC circuit breaker cannot be powered through the direct current（DC） grid system

but also significantly lower the insulation requirements and difficulty of the power supply equipment. The proposed scheme has been utilized in a ±500 kV flexible DC power grid pilot project in Zhangbei. The multi-layer isolated transformers in series can satisfy the insulation requirement of 500 kV. The internal temperature rise is less than 30 K

and the seismic intensity reaches level 9. The capacity of the designed power supply coil which is made of silicon steel and operates at power frequency is more than 5 VA

which is sufficient to the operation of the driving board. Meanwhile

the size of the coil is optimized to be small enough to fulfill large-scale application in practice.