“Natural modulation” for maximizing efficiency in power converters

A variable dc-dc transformer modulator having an input voltage and an output voltage comprising:

• a variable dc-dc transformer having a plurality of transformer elements, an inductor and an output capacitor
• the variable dc-dc transformer and the inductor comprising a series circuit connecting the input voltage to the output filter capacitor and the output voltage,
• each one of the plurality of transformer elements having first and second synchronous rectifiers connected to first and second outputs of the respective each one of the plurality of transformer elements, and
• each one of the plurality of transformer elements having a shorting switch connected across the first and second outputs of the respective each one of the plurality of transformer elements, so that
• any number of the plurality of transformer elements can be effectively removed from the variable dc-dc transformer by turning off, respectively, both the first and second synchronous rectifiers of the respective transformer elements, and
• by turning on the respective shorting switch of the respective transformer elements,
• so that
• the ratio of the output voltage to the input voltage is controlled by the quantity of the plurality of transformer elements of the variable dc-dc transformer power modulator that are effectively removed from the variable dc-dc transformer.

A variable dc-dc transformer coupled buck converter having an input voltage and an output voltage comprising:

• a buck derived switching means
• a variable dc-dc transformer,
• an inductor, and
• an output filter capacitor;
• the buck derived switching means, the variable dc-dc transformer and the inductor comprising a series circuit connecting the input voltage to the output filter capacitor and the output voltage
• the variable dc-dc transformer coupled buck converter having a normal mode for operation when the input voltage is in its normal range
• the variable dc-dc transformer coupled buck converter having an over voltage mode for operation when the input voltage is above its normal range, and
• the variable dc-dc transformer coupled buck converter having an under voltage mode for operation when the input voltage is below its normal range,
• when the variable dc-dc transformer coupled buck converter is operating in the normal mode, the buck derived switching means is saturated, the variable dc-dc transformer is nearly saturated and voltage regulation of the output voltage is accomplished by varying a ratio control input of the variable dc-dc transformer;
• when the variable dc-dc transformer coupled buck converter is operating in the over voltage mode, the variable dc-dc transformer is saturated and voltage regulation of the output voltage is accomplished by varying a duty cycle control input of the buck switching means, and
• when the variable dc-dc transformer coupled buck converter is operating in the under voltage mode, the buck derived switching means is saturated, and voltage regulation of the output voltage is accomplished by varying the ratio control input of the variable dc-dc transformer.