Subtract the given 45V from the actual voltage value detected by the measuring module, and introduce the proportional-integral regulator of the first outer loop to adjust, and the output voltage can be used as the given value of the internal current loop. Then, the given I is subtracted from the actual IL detected by the measurement module, and the output error is introduced into the second proportional-integral regulator to perform PI operation to obtain the duty cycle D of the switching device