Computer Products, Incorporated

Robert Chun Lee

Francis Man Ho

Franki Ngai Poon

Fu-Sheng Tsai

An AC-to-DC power converter draws input current through an inductor. When the input voltage of the converter is sufficiently high and the switch of the converter is on, current flows into the converter, through the inductor, to the tap of a transformer, through a first primary winding of the transformer, and through the switch. When the switch is then turned off, current continues to flow through the inductor and to the tap of the transformer but then flows through a second primary of the transformer and into a storage capacitor. Energy stored in the storage capacitor is transferred to the load when it is not possible to obtain sufficient energy from the input current to supply the load. The AC-to-DC converter has very few circuit components and low input current harmonics.

Low cost AC-to-DC converter having input current with reduced harmonics

An AC-to-DC power converter achieves greater than 80 percent power factor correction with greater than 75 percent efficiency using only one power switch, only one magnetic component, only one control loop, and a storage capacitor. The only magnetic component is a transformer having first primary winding, a second primary winding, and at least one secondary winding. During a first time interval of the period of the AC input current, the second primary winding is energized with energy previously stored in a storage capacitor. During a second time interval of the period of the AC input current, the first primary winding is energized with energy of an input current flowing through the AC input terminals. As a result, the AC-to-DC power converter drawns input current for an extended period of time before the point in time when the input voltage peaks and also for an extended period of time after the point in time when the input voltage peaks. Magnitudes of input current harmonics with respect to the fundamental input current are therefore reduced with an AC-to-DC power converter having only one magnetic

An AC-to-DC power converter achieves greater than 80 percent power factor correction with greater than 75 percent efficiency using only one power switch, only one magnetic component, only one control loop, and a storage capacitor. The only magnetic component is a transformer having first primary winding, a second primary winding, and at least one secondary winding. During a first time interval of the period of the AC input current, the second primary winding is energized with energy previously stored in a storage capacitor. During a second time interval of the period of the AC input current, the first primary winding is energized with energy of an input current flowing through the AC input terminals. As a result, the AC-to-DC power converter drawns input current for an extended period of time before the point in time when the input voltage peaks and also for an extended period of time after the point in time when the input voltage peaks. Magnitudes of input current harmonics with respect to the fundamental input current are therefore reduced with an AC-to-DC power converter having only one magnetic component.

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Hong Kong, China

Robert Chun Lee