A converter includes a first end, a second end, a first side and a second side switching circuits and a transformer. The first end includes a first positive terminal and a first negative terminal. The second end includes a second positive terminal and a second negative terminal. The first side switching circuit is coupled to the first end and includes a first bridge arm and a second bridge arm. Two terminals of the first bridge arm are coupled to the first positive terminal and the first negative terminal respectively. Two terminals of the second bridge arm are coupled to the first positive terminal and the second positive terminal respectively. The transformer includes a first side winding coupled to the first side switching circuit and a second side winding coupled to the second side switching circuit. The turns ratio of the first side winding and the second side winding is N:1.