METHOD AND APPARATUS FOR CONTROLLING PARALLELED POWER SUPPLIES
A method of controlling multiple switching power supplies connected in parallel to have respective power inputs connected to each other to receive an input power and respective power outputs connected to each other at a combined power output to supply a total output power to a load, each switching power supply configured to, when enabled and disabled, respectively supply and not supply an individual power to the combined power output, comprises: sensing a level of current indicative of the total output power; when the level is a low level, enabling an initial switching power supply of the multiple switching power supplies and disabling remaining switching power supplies of the multiple switching power supplies; and as the level increases from the low level to a high level, successively enabling the remaining switching power supplies until the remaining switching power supplies are all enabled.
1 . A method of controlling multiple switching power supplies connected in parallel to have respective power inputs connected to each other to receive an input power and respective power outputs connected to each other at a combined power output to supply a total output power to a load, each switching power supply configured to, when enabled and disabled, respectively supply and not supply an individual power to the combined power output, the method comprising:
sensing a level of current indicative of the total output power;
when the level is a low level, enabling an initial switching power supply of the multiple switching power supplies and disabling remaining switching power supplies of the multiple switching power supplies; and
as the level increases from the low level to a high level, successively enabling the remaining switching power supplies until the remaining switching power supplies are all enabled.
2 . The method of claim 1 , further comprising:
as the level decreases from the high level to the low level, successively disabling the remaining switching power supplies until all the remaining switching power supplies are disabled.
3 . The method of claim 1 , further comprising:
establishing enable thresholds that increase successively for respective ones of the remaining switching power supplies; and
as the level increases, comparing the level against the enable thresholds,
wherein successively enabling includes successively enabling the remaining switching power supplies when the level exceeds successive ones of the enable thresholds, based on results of comparing.
4 . The method of claim 3 , further comprising:
establishing disable thresholds for respective ones of the remaining switching power supplies, such that each disable threshold is less than a respective one of the enable thresholds;
as the level decreases from the high level, comparing the level against the disable thresholds; and
as the level decreases, successively disabling the remaining switching power supplies that are enabled when the level falls below successive ones of the disable thresholds, based on results of comparing, wherein the enable thresholds and the disable thresholds establish hysteresis when enabling and disabling the remaining switching power supplies.
5 . The method of claim 1 , wherein the multiple switching power supplies respectively include pulse width modulation (PWM) controllers that, when enabled and disabled, supply and do not supply PWM to one or more switching transistors of each of the multiple switching power supplies, and wherein:
enabling a particular switching power supply includes enabling a particular PWM controller of the particular switching power supply.
6 . The method of claim 5 , wherein the particular PWM controller includes an enable input to receive a voltage that enables or disables the particular PWM controller when the voltage exceeds or does not exceed a threshold voltage, and wherein:
enabling the particular PWM controller includes applying the voltage that exceeds the threshold voltage to the enable input.
7 . The method of claim 5 , wherein the particular PWM controller includes an enable input to receive a voltage that enables or disables the particular PWM controller when the voltage is less than or is not less than a threshold voltage, and wherein:
enabling the particular PWM controller includes applying to the enable input the voltage that is less than the threshold voltage.
8 . The method of claim 5 , wherein the particular PWM controller includes a duty cycle control input to receive a voltage to gradually increase a duty cycle of the PWM from zero to a maximum duty cycle as the voltage gradually increases from a low voltage to a high voltage, and wherein:
enabling the particular PWM controller includes gradually increasing the voltage from the high voltage to the low voltage.
9 . A power supply system comprising:
multiple switching power supplies having respective power inputs connected to each other and respective power outputs connected to each other at a combined output to supply a total output power to a load, each switching power supply configured to, when enabled and disabled, respectively supply and not supply an individual power to the combined output; and
a controller coupled to the multiple switching power supplies and configured to perform:
sensing a level of current indicative of the total output power;
when the level is a low level, enabling an initial switching power supply of the multiple switching power supplies and disabling remaining switching power supplies of the multiple switching power supplies; and
as the level increases from the low level to a high level, successively enabling the remaining switching power supplies until the remaining switching power supplies are enabled.
10 . The power supply system of claim 9 , wherein the controller is further configured to perform:
as the level decreases from the high level to the low level, successively disabling the remaining switching power supplies until all the remaining switching power supplies are disabled.
11 . The power supply system of claim 9 , wherein the controller is further configured to perform:
establishing enable thresholds that increase successively for respective ones of the remaining switching power supplies; and
as the level increases, comparing the level against the enable thresholds,
wherein the controller is configured to perform successively enabling by successively enabling the remaining switching power supplies when the level exceeds successive ones of the enable thresholds, based on results of comparing.
12 . The power supply system of claim 11 , wherein the controller is further configured to perform:
establishing disable thresholds for respective ones of the remaining switching power supplies, such that each disable threshold is less than a respective one of the enable thresholds;
as the level decreases from the high level, comparing the level against the disable thresholds; and
as the level decreases, successively disabling the remaining switching power supplies that are enabled when the level falls below successive ones of the disable thresholds, based on results of comparing.
13 . The power supply system of claim 9 , wherein:
each switching power supply respectively includes a pulse width modulation (PWM) controller that, when enabled and disabled, supplies and does not supply PWM to one or more switching transistors; and
the controller is configured to perform enabling a particular switching power supply by enabling a particular PWM controller of the particular switching power supply.
14 . The power supply system of claim 13 , wherein:
the particular PWM controller includes an enable input to receive a voltage that enables or disables the particular PWM controller when the voltage exceeds or does not exceed a threshold voltage; and
the controller is configured to perform enabling the particular PWM controller includes applying the voltage that exceeds the threshold voltage to the enable input.
15 . The power supply system of claim 13 , wherein:
the particular PWM controller includes an enable input to receive a voltage that enables or disables the particular PWM controller when the voltage is less than or is not less than a threshold voltage; and
the controller is configured to perform enabling the particular PWM controller includes applying to the enable input the voltage that is less than the threshold voltage.
16 . The power supply system of claim 13 , wherein:
the particular PWM controller includes a duty cycle control input to receive a voltage to gradually increase a duty cycle of the PWM from zero to a maximum duty cycle as the voltage gradually increases from a low voltage to a high voltage; and
the controller is configured to perform enabling the particular PWM controller includes gradually increasing the voltage from the low voltage to the high voltage.
17 . A method of controlling multiple power supplies connected in parallel to supply a total output power to a load, each power supply configured to, when enabled and disabled, respectively supply and not supply an individual power to the total output power, the method comprising:
establishing pairs of hysteretic thresholds that successively increase for respective ones of the multiple power supplies;
sensing a level of current indicative of the total output power; and
starting when the multiple power supplies are all disabled, controlling the multiple power supplies based on the level by:
as the level increases, successively enabling the multiple power supplies as the level successively exceeds enable thresholds of the pairs of the hysteretic thresholds until the multiple power supplies are all enabled; and
after the multiple power supplies are all enabled, as the level decreases, successively disabling the multiple power supplies as the level successively falls below disable thresholds of the pairs of the hysteretic thresholds.
18 . The method of claim 17 , wherein the multiple power supplies comprise switching power supply that include respective pulse width modulator (PWM) controllers, wherein:
successively enabling includes successively enabling the PWM controllers.
19 . The method of claim 18 , wherein:
successively disabling includes successively disabling the PWM controllers.
20 . The method of claim 17 , further comprising:
as the level increases, first comparing the level against the enable thresholds, and successively enabling based on first results of first comparing; and
as the level decreases, second comparing the level against the disable thresholds, and successively disabling based on second results of second comparing.