Control method for bidirectional DC-DC converters

摘要

A control method for bidirectional DC-DC converter includes: operating a bidirectional DC-DC converter having a low voltage side including a plurality of low-voltage-side switches, a voltage clamping switch and a voltage clamping capacitor, and a high voltage side including a plurality of high-voltage-side switches in a boost mode; switching the voltage clamping switch with a predetermined duty cycle prior to switching on all of the low-voltage-side switches; adjusting the predetermined duty cycle of the voltage clamping switch to be smaller than a turn-off interval of the low-voltage-side switches to reduce the conduction loss of the low-voltage-side switches and the voltage clamping switch; alternatively, operating the DC-DC converter in a buck mode; and adjusting and extending the duty cycle of the low-voltage-side switches to overlap a turn-off time of the high-voltage-side switches to reduce the conduction loss of the low-voltage-side switches.

主权项

1. A control method comprising:
operating a bidirectional DC-DC converter in a boost mode, with the bidirectional DC-DC converter including a high voltage side and a low voltage side, with the low voltage side provided with a plurality of low-voltage-side switches, a voltage clamping switch and a voltage clamping capacitor, with the plurality of low-voltage-side switches including a plurality of first low-voltage-side switches and a plurality of second low-voltage-side switches; alternatively switching on and off the plurality of first low-voltage-side switches and the plurality of second low-voltage-side switches including cutting off the plurality of first low-voltage-side switches or the plurality of second low-voltage-side switches and utilizing the voltage clamping capacitor to clamp a voltage via a diode reversely parallel-connected to the voltage clamping switch situated in a cut-off state, with switching on the voltage clamping switch prior to switching on all of the plurality of low-voltage-side switches to discharge power energy of the voltage clamping capacitor and to switch on the plurality of first low-voltage-side switches or the plurality of second low-voltage-side switches by a zero-voltage switching operation, thereby reducing a duty cycle of switching the voltage clamping switch; and switching on the voltage clamping switch with a predetermined duty cycle with a switching-on time interval at a first point of a turn-off time interval of at least one set of the plurality of low-voltage-side switches prior to nearly switching on all of the plurality of low-voltage-side switches and switching off the voltage clamping switch at a second point prior to alternatively switching on the at least one set of the plurality of low-voltage-side switches; wherein the switching-on time interval of the voltage clamping switch is smaller than a turn-off time interval and a period of charging and discharging time of the voltage clamping capacitor is reduced due to reduction of the duty cycle of switching the voltage clamping switch.