High power-factor control circuit and method for switched mode power supply
AssigneeBCD Semiconductor Manufacturing Limited
InventorsShihai Zhu, Zeqiang Chen, Xuegang Ren, Yajiang Zhu
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Abstract
A switch mode power supply (SMPS) system includes a rectifying circuit for coupling to an AC input voltage and a transformer having a primary winding for coupling to the rectifying circuit and a secondary winding coupled to the primary winding. The system also has a power switch coupled to the primary winding and a control circuit coupled to the power switch. The control circuit is configured to control current flow in the primary winding such that an envelop waveform formed by peak points of current pulses are in phase with the magnitude of the AC input voltage. Moreover, the SMPS system is configured to provide a constant average output current.
Claims22
A switch mode power supply (SMPS) system, comprising:
- a rectifying circuit for coupling to an AC input voltage;
- a transformer having a primary winding for coupling to the rectifying circuit and a secondary winding coupled to the primary winding;
- a power switch coupled to the primary winding;
- and
- a control circuit coupled to the power switch, the control circuit being configured to control current pulses in the primary winding such that an envelop waveform formed by peak points of the current pulses are in phase with the AC input voltage;
- wherein the SMPS system is configured to provide a constant average output current.
A control circuit for a switch mode power supply (SMPS), comprising:
- a first input terminal for coupling to a periodic input voltage;
- a second input terminal for sensing a current flow in the SMPS;
- and
- an output terminal for providing a control signal to a power switch for regulating the current flow in the SMPS;
- wherein the control circuit is configured to control current pulses in the SMPS such that an envelop formed by peak points of the current pulses are in phase with the periodic input voltage, and the control circuit is configured to enable the SMPS to provide a constant average output current.
Dependencies are inferred from the claim text.