Control methods for switching power supplies
AssigneeLeadtrend Technology Corp.
InventorWen-Chung Yeh
Life of this patent
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Abstract
An embodiment provides a control method capable of controlling a switching-mode power supply to provide an output power source. The switching-mode power supply has a winding coupled to an input power source and controlled by a switch to be energized or de-energized. The maximum current peak through the winding is set to be a predetermined value. A discharge time of the winding in a switching cycle period is detected. The switching cycle period of the switch is controlled to keep the ratio of the discharge time to the switching cycle period as a constant.
Claims19
A control method, for controlling a switching power supply comprising a transformer coupled to an input power source, the transformer controlled by a switch for charging or discharging to generate an output power source, the control method comprising:
- providing a capacitor;
- storing a difference between a real electric charge and a expected electric charge in the capacitor, wherein the real electric charge corresponds to the electric charge flowing through the transformer within a switching cycle period of the switch, and the expected electric charge corresponds to the electric charge expected in the switching cycle period;
- and
- varying the real electric charge or the expected electric charge in a subsequent switching cycle period according to a voltage of the capacitor, to cause the real electric charge approximately equal to the estimated electric charge in the subsequent switching cycle period.
A constant current control method for a switching power supply comprising a switch and a winding coupled in series to an input power source, the switching power supply providing an output power source, the constant current control method comprising:
- providing a first negative feedback loop, for detecting a winding current flowing through the winding so as to generate an estimated average current corresponding to an average current flowing through the winding;
- and
- providing a second negative feedback loop, for making an average output current of the output power source approximately equal to a predetermined average output current according to the estimated average current.
Dependencies are inferred from the claim text.