Patent ID: 9025349
Filing Date: 2015-05-05
Classification: H02M

Abstract:
1. A power system, comprising: a power output circuit; a soft start circuit coupled to an input end of the power output circuit; a constant-current source that supplies power to the soft start circuit; a loop circuit coupled to the power output circuit; and a precharge circuit that charges the loop circuit capacitor; wherein the loop circuit comprises a loop circuit capacitor; wherein the precharge circuit charges the loop circuit capacitor before the soft start circuit of the power system is turned off causing the loop circuit of the power system to be turned on to supply power; wherein an input end of the precharge circuit is coupled to the constant-current source, and an output end of the precharge circuit is coupled to the loop circuit capacitor; the precharge circuit comprises a precharge switch, the precharge switch is turned on before the soft start circuit of the power system to supply power; wherein the constant-current source is coupled to the power output circuit by the soft start switch, the precharge circuit is coupled to the loop circuit capacitor by the precharge switch, and the loop circuit is coupled to the power output circuit by a transfer switch; logical operation of the soft start switch is the same as logical operation of the precharge switch, and is opposite to logical operation of the transfer switch; wherein the soft start circuit comprises a first comparator; an inverting input end of the first comparator is coupled to a first reference voltage, a non-inverting input end of the first comparator is coupled to the constant-current source and is coupled to a ground terminal of the power system by the soft start capacitor, and an output end of the first comparator is coupled to control ends of the soft start switch, the precharge switch, and the transfer switch; wherein the loop circuit comprises a second comparator; a non-inverting input end of the second comparator is coupled to a second reference voltage, a inverting input end of the second comparator is coupled to a load feedback, and the output end of the second comparator is coupled to the power output circuit by the transfer switch; the loop circuit capacitor is in series between the output end and the inverting input end of the second comparator; when voltage of the soft start capacitor is less than the first reference voltage, the first comparator turns on the soft start switch and the precharge, and turns off the transfer switch; when the voltage of the soft start capacitor is greater than the first reference voltage after the soft start capacitor is fully charged, the first comparator turns off the soft start switch and the precharge switch, and turns on the transfer switch.