On-board charger, dcdc converter and control method

A buck DCDC converter, comprising:

• a controller;
• a main power transistor;
• a controllable switching transistor;
• and
• an inductor;
• wherein
• the inductor is connected in series with the main power transistor;
• an output terminal of the buck DCDC converter is connected to a battery;
• and
• the controller is configured to:
• when the buck DCDC converter is performing a startup process, generate a driving signal for the main power transistor by soft starting a current loop to control a current flowing through the inductor to be gradually increased, wherein a predetermined current of the current loop is determined based on a reference current outputted by a voltage loop and an output result of a soft start function;
• and
• after the buck DCDC converter completes the startup process, generate a driving signal for the main power transistor by cascading the voltage loop and the current loop, wherein the voltage loop is configured to output the reference current to an input terminal of the current loop.

A method for controlling an on-board charger, wherein the on-board charger comprises a power factor corrector, a high-voltage direct-current converter, a low-voltage direct-current converter and a controller, an input terminal of the high-voltage direct-current converter is connected to an output terminal of the power factor corrector, an input terminal of the low-voltage direct-current converter is connected to an output terminal of the high-voltage direct-current converter, an output terminal of the low-voltage direct-current converter is connected to a low-voltage battery, and the low-voltage direct-current converter comprises a main power transistor and a controllable switching transistor;

• and
• the method comprises:
• generating, when the low-voltage direct-current converter is performing a startup process, a driving signal for the main power transistor by soft starting a current loop to control a current flowing through an inductor connected in series with the main power transistor to be gradually increased, wherein a predetermined current of the current loop is determined based on a reference current outputted by a voltage loop and an output result of a soft start function;
• and
• generating, after the low-voltage direct-current converter completes the startup process, a driving signal for the main power transistor by cascading the voltage loop and the current loop, wherein the voltage loop is configured to output the reference current to an input terminal of the current loop.