Constant inrush current circuit for AC input power supply unit
View Patent ↗A power supply circuit includes a rectifier module configured to rectify an input voltage and a capacitor including a first terminal coupled to the rectifier module. In addition, the power supply circuit includes first and second transistors. The first transistor couples to a second terminal of the capacitor, and the second transistor couples in series to the first transistor. The power supply circuit also includes a resistor, configured to set an inrush current value, in parallel with the second transistor. When coupled to a power supply, the power supply circuit is configured to turn-on the first transistor such that an inrush current flows, at the inrush current value, through the capacitor, first transistor, and resistor. After a delay time, the power supply circuit is configured to turn-on the second transistor such that the inrush current drops to around zero, thus maintaining a low impedance path during steady-state operation.
1. A power supply circuit, comprising:
a rectifier module including first and second input terminals and first and second output terminals, the rectifier module configured to rectify an input voltage;
an output capacitor including a first terminal coupled to the first output terminal of the rectifier module;
a first transistor including first and second current electrodes, the first current electrode coupled to a second terminal of the output capacitor;
a second transistor including third and fourth current electrodes, the third current electrode coupled to the second current electrode of the first transistor, and the fourth current electrode coupled to the second output terminal of the rectifier module; and
a resistor connected in parallel with the second transistor, the resistor configured to set an inrush current value;
wherein the power supply circuit is configured, when the first and second input terminals of the rectifier module are coupled to a power supply, to turn-on the first transistor such that an inrush current flows, at the inrush current value, through the output capacitor, the first transistor, and the resistor; and
wherein the power supply circuit is configured, after the rectifier module has been coupled to the power supply for a specified delay time, to ensure that the inrush current has dropped to a value of about zero amperes, to turn-on the second transistor.
2. The power supply circuit of claim 1 , further comprising a charging module coupled in series between the first output terminal of the rectifier module and a gate electrode of the first transistor.
3. The power supply circuit of claim 2 , further comprising a Zener diode coupled between the gate electrode of the first transistor and the second output terminal of the rectifier module, the Zener diode configured to set a gate-to-ground voltage for the first transistor.
4. The power supply circuit of claim 1 , further comprising a delay circuit coupled between the rectifier module and a gate electrode of the second transistor.
5. The power supply circuit of claim 4 , further comprising a Zener diode coupled between the gate electrode of the second transistor and the second output terminal of the rectifier module, the Zener diode configured to set a gate-to-ground voltage for the second transistor.
6. The power supply circuit of claim 1 , further comprising a fast recovery diode connected anti-parallel to the first and second transistors.
7. The power supply circuit of claim 4 , further comprising a discharging module coupled to the gate electrode of the second transistor, the discharging module configured, when the first and second input terminals of the rectifier module are disconnected from the power supply, to discharge the gate electrode of the second transistor.
8. The power supply circuit of claim 1 , wherein the first transistor includes a 500V-600V N-channel power MOSFET, and the second transistor includes a 30V N-channel power MOSFET.
9. An information handling system (IHS), comprising:
a processor;
a memory coupled to the processor; and
a power supply device coupled to processor, the power supply device including:
a diode rectifier bridge including first and second input terminals and first and second output terminals, the second output terminal coupled to a ground terminal, and the diode rectifier bridge configured to rectify an input voltage;
a bulk capacitor including a first terminal coupled to the first output terminal of the diode rectifier bridge;
a first transistor including first and second current electrodes, the first current electrode coupled to a second terminal of the bulk capacitor;
a second transistor including third and fourth current electrodes, the third current electrode coupled to the second current electrode of the first transistor, and the fourth current electrode coupled to the ground terminal; and
a resistor connected in parallel with the second transistor, the resistor configured to set an inrush current value;
wherein the power supply device is configured, when the first and second input terminals of the diode rectifier bridge are coupled to a power supply, to turn-on the first transistor such that an inrush current flows, at the inrush current value, through the bulk capacitor, the first transistor, and the resistor; and
wherein the power supply device is configured, after the diode rectifier bridge has been coupled to the power supply for a specified delay time, to ensure that the inrush current has dropped to a value of about zero amperes, to turn-on the second transistor.
10. The IHS of claim 9 , wherein the power supply device further includes a charging circuit coupled in series between the first output terminal of the diode rectifier bridge and a gate electrode of the first transistor.
11. The IHS of claim 10 , wherein the power supply device further includes a Zener diode coupled between the gate electrode of the first transistor and the second output terminal of the diode rectifier bridge.
12. The IHS of claim 9 , wherein the power supply device further includes a delay circuit coupled between the diode rectifier bridge and a gate electrode of the second transistor.
13. The IHS of claim 12 , wherein the power supply device further includes a Zener diode coupled between the gate electrode of the second transistor and the second output terminal of the diode rectifier bridge.
14. The IHS of claim 9 , wherein the first transistor is configured, when the inrush current flows through the first transistor at the inrush current value, to operate in a linear region of operation.
15. The IHS of claim 12 , wherein the power supply device further includes a discharge circuit coupled to the gate electrode of the second transistor, the discharging module configured to discharge the gate electrode of the second transistor.
16. A method for limiting an inrush current, comprising:
providing a power supply circuit, the power supply circuit comprising:
a rectifier module including first and second input terminals and first and second output terminals, the rectifier module configured to rectify an input voltage;
an output capacitor including a first terminal coupled to the first output terminal of the rectifier module;
a first transistor including first and second current electrodes, the first current electrode coupled to a second terminal of the output capacitor;
a second transistor including third and fourth current electrodes,
the third current electrode coupled to the second current electrode of the first transistor, and the fourth current electrode coupled to the second output terminal of the rectifier module; and
a resistor connected in parallel with the second transistor, the resistor configured to set an inrush current value;
coupling the first and second input terminals of the rectifier module to a power supply;
turning-on the first transistor such that the inrush current flows, at the inrush current value, through the output capacitor, the first transistor, and the resistor; and
turning-on, after a specified delay time, the second transistor, wherein turning-on the second transistor after the specified delay time ensures that the inrush current has dropped to a value of about zero amperes.
17. The method of claim 16 , wherein the turning-on the first transistor further comprises charging a gate electrode of the first transistor by a charging module coupled in series between the first output terminal of the rectifier module and the gate electrode of the first transistor.
18. The method of claim 16 , further comprising fully charging, by the inrush current and prior to the specified delay time, the output capacitor.
19. The method of claim 16 , further comprising operating the first transistor, while the inrush current flows through the first transistor at the inrush current value, in a linear region of operation.
20. The method of claim 16 , further comprising:
disconnecting the first and second input terminals of the rectifier module from the power supply; and
discharging the gate electrode of the second transistor module by a discharging module coupled to the gate electrode of the second transistor.