Abstract: In order to solve the problem that the battery car capacitance is damaged because charging voltage of the battery charging systems used in the market is not matched with the model of the battery car capacitance，a new battery charger is proposed． The battery charging system uses NCP1654 as the core control chip，and the Boost Chopper is used as the main circuit． The new silicon carbide semiconductor device is used as the main switching device to convert alternating current into direct current． When the AC voltage on the power supply changes from 180 V to 260 V，the device can operate normally． The intelligent battery car charging system outputs two DC voltages，42 V and 27 V respectively，and the maximum output current are both 2 A． The load regulation is 0． 1，and the peak-to-peak value of output noise ripple voltage is less than 1． 5 V． The protection circuit in the charging device prevents spike voltage and surge current during start － up，and prevents over charge problem． Considering the user experience of the intelligent battery charging system，the touch screen is selected as the operation interface． The STM32 demoboard is used to detect the output voltage and output current，control the output voltage amplitude of the charging system． The STM32 can also detect the output voltage and current and control the amplitude of the output voltage． After testing，the battery charging system reached the design requirements．

Key words: switching mode power supply, Boost chopper, STM32