Power electronics technology plays an important role in the development of the auxiliary converter. Power semiconductor devices such as thyristor, insulated gate bipolar transistor and metal oxide semiconductor field effect transistor have realized high function control and transformation of electric energy and realized auxiliary functions. The converter has high power, integration and high power. With the continuous exploration of practice, the control strategy of the converter has been further studied. As for the electric locomotives that have been working for some time, they need to replace the converter and other equipment due to problems such as aging equipment. In order to reduce costs and take into account industrial stability,