New constant-frequency current-mode control for power converters, stable for all values of duty ratio, and usable in all four quadrants

A constant-frequency, current-mode, pulse-width modulator (PWM) for switching power converters is presented. The PWM is stable for any value of the duty ration (δ) and is suitable for operation in one to four quadrants of the output current-voltage plane. The control system can be used with most DC-DC power-converter topologies. Due to its unique properties of δ range stability and four-quadrant operation, the control process is particularly useful in DC-AC conversion. The process is clearly advantageous compared to the other current-mode control method, the bang-bang process. It has all the advantages inherent to constant-frequency operation, including the possibility of paralleling different converters without low-frequency beating and the suppression of low-frequency subharmonics in DC-AC conversion