Patent ID: 9190905
Filing Date: 2015-11-17
Classification: H02M

Abstract:
1. A switching power supply device, comprising: a positive voltage output circuit connected to a direct-current power supply, the positive voltage output circuit including a first switching element that is switched on and off by a switching control signal, a voltage boosting inductor, a first rectifying element and a first capacitor; a negative voltage output circuit connected to the direct-current power supply, the negative voltage output circuit including a second switching element that is switched on and off by the switching control signal, a voltage dropping inductor, a second rectifying element and a second capacitor; and an adder circuit configured to add switching currents flowing when the first switching element and the second switching element are operated, wherein the switching control signal is input to the first and second switching elements such that the first and second switching elements are switched on and off together, wherein the first switching element, the voltage boosting inductor, the first rectifying element and the first capacitor of the positive voltage output circuit are in a symmetrical arrangement with the second switching element, the voltage dropping inductor, the second rectifying element and the second capacitor of the negative voltage output circuit, and the positive voltage output circuit is configured to generate a first switching current and the negative voltage output circuit is configured to generate a second switching current, wherein the first switching current of the positive voltage output circuit and the second switching current of the negative voltage output circuit are generated in mutually opposite directions and inputted to the adder circuit, and wherein one terminal of the first switching element is connected to a midpoint of the voltage dropping inductor, and one terminal of the second switching element is connected to a midpoint of the voltage boosting inductor, and wherein the voltage boosting inductor and the voltage dropping inductor are center-tap inductors, wherein a third capacitor is provided between the midpoint of the voltage boosting inductor and a grounding point, and a fourth capacitor is provided between the midpoint of the voltage dropping inductor and the grounding point, and wherein a third switching element is provided between one end of the voltage boosting inductor and the midpoint of the voltage dropping inductor, and a fourth switching element is provided between one end of the voltage dropping inductor and the midpoint of the voltage boosting inductor.