Start-up circuit and control for high power isolated boost DC/DC converters

A system to active clamp isolated high power boost converters, the system comprising:

• a primary circuit comprising at least two bridge leg components;
• a secondary circuit comprising at least two bridge leg components;
• a transformer coupling the primary circuit and the secondary circuit;
• the primary circuit further comprising a clamping switch;
• and
• a start-up circuit comprising a high frequency rectifier diode, a high frequency capacitor electrically coupled across the high frequency rectifier diode, and an output capacitor electrically coupled across an output of the secondary circuit, whereby bridge leg components of the primary circuit are protected from in-rush current in a start-up mode, wherein the primary circuit further comprises a snubber resistor, whereby clamping energy is dissipated.

A method to active-clamp isolated high power boost converters comprised of a transformer connected to a primary circuit and a secondary circuit, comprising:

• turning off at least two primary circuit switches during a start-up mode;
• activating a start-up circuit;
• clamping the primary circuit during the start-up mode using a clamping switch;
• and
• snubbing energy, whereby the at least two primary circuit switches are protected from voltage spikes in the start-up mode.

A boost-mode operation timing control method to determine switching of primary side circuit controllers by a first and a second set of duty cycle control signals, the method comprising:

• turning on a first pair of primary side diagonal bridge leg components during normal boost-mode operation at a rise edge of a first pulse width modulation (PWM) signal;
• turning off the first pair of primary side diagonal bridge leg components during normal boost-mode operation at a fall edge of a second PWM signal;
• turning on a second pair of primary side diagonal bridge leg components during normal boost-mode operation at a rise edge of the second PWM signal;
• turning off the second pair of primary side diagonal bridge leg components during normal boost-mode operation at a fall edge of the first PWM signal;
• turning on all of the primary side diagonal bridge leg components when at least one duty cycle control signal is high;
• alternating between turning off the first pair of primary side diagonal bridge leg components and turning off the second pair of primary side diagonal bridge leg components in subsequent intervals when both duty cycle control signals are low.