Direct current power supply device

摘要

In a direct-current power supply device that includes a smoothing capacitor C1, which performs a DC/DC converter operation, a transformer T1, a switching element Q1, a diode D2, a smoothing capacitor C2, a reactor L1, which performs a PFC operation, a fast recovery diode D1 and a switching element Q1, when compared with the case of a rated load, the voltage of the smoothing capacitor C1 of a PFC circuit rises at a time when a load is light. Therefore, the following has been required: a capacitor having a sufficient withstanding voltage rating, or an operation of connecting a plurality of capacitors in series or any other operation to secure a voltage-withstanding capability.;A direct-current power supply device 1, in which a switching element Q1 used by a PFC circuit is shared as a switching element Q1 by a DC/DC converter, includes voltage suppression means (switching elements Q2 and Q3 and resistance R2) for supplying electric charge accumulated in a smoothing capacitor C1 to a power supply Vcc of a control circuit CTL1 that controls the switching element Q1 at a time when a load is light in order to suppress a rise in voltage in the smoothing capacitor C1.

主权项

1. A direct-current power supply device that converts energy obtained from an alternating-current power supply into direct-current energy, the device comprising:
a rectifier that converts alternating-current voltage of the alternating-current power supply into direct-current voltage; a transformer that includes a primary winding, which includes a tap at a connection point where a first primary winding and a second primary winding are connected, and a secondary winding; a primary-side smoothing capacitor whose positive electrode-side terminal is connected to a terminal at a side opposite to the tap of the first primary winding and whose negative electrode-side terminal is connected to a negative electrode-side output terminal of the rectifier; a first switching element whose drain and source terminals are connected between the negative electrode-side output terminal of the rectifier and a terminal at a side opposite to the tap of the second primary winding; a reactor and backflow preventing diode that are connected in series between a positive electrode-side output terminal of the rectifier and the tap of the transformer; a direct-current smoothing circuit that includes a rectifying diode, which is connected to the secondary winding of the transformer, and a secondary-side smoothing capacitor; and discharging means for detecting a light-load state of an output and discharging electric charge of the primary-side smoothing capacitor in a way that suppresses an increase in voltage of the primary-side smoothing capacitor.