Research and design of a wide-output and high-efficient charger

With the fast development of power batteries in electric vehicles, charging technology has been received a lot of research. It is difficult to get wide charging voltage and realize high efficient at any charging state. This paper proposes a two stage charger, which contains totem pole bridgeless power factor correction (PFC) and series resonant circuit (LLC). PFC can meet sinusoidal wave of input current while LLC can achieve high efficient for its soft switching. When bus voltage is fixed, Phase shift angle or operating frequency of LLC will not be in reasonable range which keep charger on high-efficient state. So the strategy of dynamical changing of bus voltage with the charging voltage is put forward, reducing the range of frequency changes and improving efficient at both ends of the output voltage. Finally, a charger prototype is made, whose input is 130VAC, output voltage ranges from 130VDC to 200VDC, bus voltage ranges from 200VDC to 240VDC. Experimental efficient is 91.8% on rated state; by using new strategy efficient can be raised from 87.4% to 90.1% at 130V output, from 89.3% to 90.1% at 200V output, respectively.