METHOD OF REGULATING AN OUTPUT VOLTAGE OF A POWER CONVERTER BY SENSING THE OUTPUT VOLTAGE DURING A FIRST TIME INTERVAL AND CALCULATING A NEXT CURRENT VALUE IN AN INDUCTOR SUFFICIENT TO BRING THE OUTPUT VOLTAGE TO A TARGET VOLTAGE WITHIN A SECOND TIME INTERVAL IMMEDIATELY FOLLOWING THE FIRST TIME INTERVAL AND VARYING A DUTY CYCLE OF A SWITCH DURING THE SECOND TIME INTERVAL
View Patent ↗The output voltage of a power converter is controlled by comparing the output voltage to a target output voltage during a first time interval and calculating an inductor current required in a second time interval immediately following the first time interval to increase the output voltage to the target output voltage. A duty cycle of a switch is varied to modify the current in the inductor during the second time interval according to the calculated inductor current. In one embodiment a fixed duty cycle response is provided if the output voltage is less than a predefined maximum and greater than a predefined minimum. In another embodiment the duty cycle of the switch is bounded by a predetermined maximum and minimum value.
1. A method for regulating an output voltage applied to a load at an output terminal of a power converter, the power converter including an output capacitor coupled between the output terminal and a ground reference, and an inductor that is selectably coupled by a switch between a power supply and the ground reference, the method comprising:
sensing the output voltage during a first time interval; and
when the output voltage sensed deviates from a target value by a predetermined value;
calculating a next current value in the inductor sufficient to bring the output voltage to a target voltage within a second time interval immediately following the first time interval; and
varying a duty cycle of the switch to modify the current in the inductor during the second time interval, according to the calculated next current, the duty cycle being the portion of the second time interval during which the switch couples the inductor to the power supply.
2. A method as in claim 1 , wherein the duty cycle is varied by less than an amount necessary to bring the output voltage to the target voltage.
3. A method as in claim 2 , wherein the duty cycle is varied by an amount according to the magnitude of the difference between the output voltage sensed during the first time interval and the target voltage.
4. A method as in claim 3 , wherein the duty cycle is varied by an amount greater than proportionally to the magnitude of the difference between the output voltage sensed during the first time interval and the target voltage.
5. A method as in claim 1 , wherein the duty cycle is varied by less than an amount necessary to bring the inductor to a saturation current.
6. A method as in claim 1 , wherein the duty cycle is varied by less than a predetermined amount that is less than 1.
7. A method as in claim 1 , wherein the duty cycle is varied by more than a predetermined amount that is greater than 0.
8. A method as in claim 1 , wherein a high limit and a low limit are defined relative to target voltage, and wherein when the voltage sensed deviates from the target voltage by more than the predetermined value but between the high and the low limits, the next current value and the resulting varying of the duty cycle are provided as fixed amounts.
9. A method as in claim 8 , wherein the power converter operates under a low power mode when the voltage sensed is between the high and the low limits.
10. A method for regulating an output voltage applied to a load at an output terminal of a power converter, the power converter including an output capacitor coupled between the output terminal and a ground reference, and an inductor that is selectably coupled by a switch between a power supply and the ground reference, the method comprising:
sensing the output voltage and a current in the inductor during a first time interval; and
calculating a next current value in the inductor sufficient to bring the output voltage to a target voltage within a second time interval immediately following the first time interval; and
varying, within a predetermined range, a duty cycle of the switch to modify the current in the inductor during the second time interval, according to the calculated next current, the duty cycle being the portion of the second time interval during which the switch couples the inductor to the power supply.
11. A method as in claim 10 , wherein the predetermined range is bounded by a maximum duty cycle that is less than 100%.
12. A method as in claim 10 , wherein the predetermined range is bounded by a minimum duty cycle that is greater that 0%.
13. A method as in claim 10 , wherein the duty cycle is varied by less than an amount necessary to bring the output voltage to the target voltage.
14. A method as in claim 13 , wherein the duty cycle is varied by an amount according to the magnitude of the difference between the output voltage sensed during the first time interval and the target voltage.
15. A method as in claim 14 , wherein the duty cycle is varied by an amount greater than proportionally to the magnitude of the difference between the output voltage sensed during the first time interval and the target voltage.
16. A method as in claim 10 , wherein the duty cycle is varied by less than an amount necessary to bring the inductor to a saturation current.
17. A method as in claim 10 , wherein the power converter is one of a plurality of power converters coupled to the power supply.