Bidirectional insulating dc-dc converter, control apparatus therefor, and operating method thereof

A control apparatus for a bidirectional insulating DC-DC converter comprising:

• a step-down circuit including an active clamp forward converter circuit and configured to step down a voltage applied from a first battery and output the stepped-down voltage to a second battery, a discharge voltage of the first battery being relatively higher than that of the second battery, and a step-up circuit including an active clamp flyback converter circuit, connected in parallel to the step-down circuit and configured to step up a voltage applied from the second battery and output the stepped-up voltage to the first battery, the control apparatus comprising:
• a step-down circuit controller configured to control the step-down circuit in a peak current mode control method;
• and
• a step-up circuit controller configured to control the step-up circuit in an average current mode control method,
• wherein the step-down circuit controller comprises a pulse width modulation (PWM) control integrated circuit (IC) configured to output a PWM signal for PWM switching control of a semiconductor switch element of the step-down circuit, and a microcomputer configured to provide a control signal to the PWM control IC, and
• the step-up circuit controller comprises a PWM control IC configured to output a PWM signal for PWM switching control of a semiconductor switch element of the step-down circuit, and a microcomputer configured to provide a control signal to the PWM control IC.

An operating method of a bidirectional insulating DC-DC converter comprising a step-down circuit configured to step down a voltage applied from a first battery and output the stepped-down voltage to a second battery, a discharge voltage of the first battery being relatively higher than that of the second battery, a step-up circuit configured to step up a voltage applied from the second battery and output the stepped-up voltage to the first battery, and a bidirectional back-to-back semiconductor switch element configured to separate a second voltage stage, the operating method comprising:

• (1) when a starting operation of a vehicle is performed, determining whether a failure of the bidirectional insulating DC-DC converter occurs;
• (2) when the failure occurs, performing a starting impossible process, and if the failure does not occur, turning the bidirectional back-to-back semiconductor switch element in the second voltage stage of the bidirectional insulating DC-DC converter on and determining whether a difference in voltage between both ends of the bidirectional back-to-back semiconductor switch element occurs;
• (3) when the voltage difference occurs, performing the starting impossible process for safety, and when the voltage difference does not occur, operating the step-up circuit of the bidirectional insulating DC-DC converter and charging the first battery;
• (4) during the charging of the first battery, performing a diagnosis on the second battery, and when the diagnosis is completed, stopping the operation of the step-up circuit;
• and
• (5) operating the step-down circuit and performing charging of the second battery.