The invention discloses a multi-
mode control method for a
voltage source type semi-active bridge DC-DC (
Direct Current) converter, which belongs to the direction of
high frequency switching power supply in the field of
power electronics. The implementation method of the invention comprises the following steps that: in the case of
heavy load, the converter operates in a traditional
single phase shift
control mode, the switching period is constant, and VAB high level time or low level time is constant; a output
voltage Vout is adjusted to be stable by adjusting the phase shift between a input side
voltage and a output side voltage; in the case of
light load, the converter operates in a
frequency modulation + PWM (
Pulse Width Modulation) mode, and the VAB high level time or the low level timeis constant; VAB
duty cycle is adjusted to be stable by adjusting a
switching frequency, that is, a VAB period, that is, a
fixed width frequency modulation mode; and in the case of
extremely light load and no load, the converter operates in a
constant frequency + PWM mode, that is, a
fixed frequency width regulation mode. Three control
modes can switch automatically and seamlessly based on load cases. According to the multi-
mode control method for the
voltage source type semi-active bridge DC-
DC converter, conversion efficiency of the converter under the
light load can be significantly improved, the converter has high conversion efficiency within a full load range, and
power density of the converter is improved.