Switch-mode AC-to-DC converter

The switch-mode power supply having a power factor substantially equal to unity, coupled to a utility source for receiving an unrectified AC input voltage and drawing an input current therefrom, the switch-mode power supply comprising:

• shaping means coupled to the utility source for shaping the input current;
• H-bridge driver means having first and second switching pairs coupled to the shaping means for receiving the AC input voltage and the input current for generating a DC bulk voltage therefrom, the H-bridge driver means further coupled for receiving a first plurality of switching signals wherein the first plurality of switching signals alternately switch the first and second switching pairs such that the input current is drawn to substantially follow the unrectified AC input voltage;
• regulator means coupled for receiving the unrectified AC input voltage and input current, the regulator means scaling the AC voltage into a reference current signal, the reference current signal representing a desired input current for achieving a unity power factor, the regulator means further comparing the reference current signal and the input current and generating a first error signal therefrom;
• feedback means coupled for receiving the DC bulk voltage and a first reference voltage and generating a second error signal therefrom for regulating the DC bulk voltage, the second error signal being further offset by a programmable constant, K;
• and
• first controller means coupled to the regulator and feedback means for generating the plurality of switching signals by multiplying the first error signal and the offset second error signal to control the first and second switching pairs of the H-driver means.

A switch-mode power supply coupled to a utility source for receiving an unrectified AC input voltage and drawing an input current therefrom, using negative feedback to reduce harmonics injected into the utility source and to ensure a power factor substantially equal to unity, the switch-mode power supply comprising:

• an inductor coupled to the utility source for shaping the input current;
• an H-bridge driver having first and second switching pairs coupled to the inductor for receiving the unrectified AC input voltage and the input current for generating a DC bulk voltage therefrom, the H-bridge driver further coupled for receiving a first a first plurality of switching signals, wherein the first plurality of switching signals alternately switch the first and second switching pairs such that the input current is drawn to continually flow in the H-bridge driver;
• an input current regulator coupled for receiving the unrectified AC input voltage and the input current, the input current regulator filtering and scaling the AC input voltage into a reference current signal, the reference current signal representing a desired input current necessary for achieving a unity power factor, the input current regulator further comprising the reference current signal and the input current and generating a first error signal therefrom;
• a DC bulk regulator coupled for receiving for receiving the DC bulk voltage and first reference voltage and generating a second error signal therefrom for regulating the DC bulk voltage, the second error signal being further offset by a constant, K, to adjust the effect the second error signal has upon the H-bridge driver;
• and
• a controller coupled to the input current regulator and the DC bulk regulator for receiving the first and second error signals therefrom and generating the plurality of switching signals by multiplying the first error signal by the second error signal, the plurality of switching signals facilitated the control of the first and second switching pairs of the H-driver.