The load box can be divided into pure resistive load, inductive load and capacitive load; it can also be divided into resistance-inductance integration, resistance-capacitance integration and resistance-inductance-capacitance integration. Pure resistive load can be divided into pure resistive non-inductive load and pure resistive inductive load, but inductive and non-inductive are relative, the inductive amount of non-inductive will be relatively low, and there is no pure non-inductive load. Under different operating frequencies of the power supply, control the allowable inductance value of the high-power load box.