Power supply device with low standby power consumption

A power device transforms input power into power for output, and includes an input unit, a power factor unit, an output unit, a power saving unit, and a control signal port. The power saving unit includes a first electronic switch, a first diode and a single-direction switch. The first electronic switch is connected between the input unit and the power factor unit. An anode of the first diode is connected to the input unit, and a cathode of the first diode is connected to the output unit. The single-direction switch is connected to the power factor unit and the output unit to block current from the output unit to the power factor unit. The control signal port controls an on/off state of the first electronic switch.

BACKGROUND

1. Technical Field

The disclosure relates to power devices, and particularly to a power device with low standby power consumption.

2. Description of Related Art

FIG. 1is a schematic diagram of a commonly used power device100. The power device100includes an input unit10, a power factor unit11, an output unit12, and a control signal port13. The output unit12includes an output transformer T1having two secondary windings N2and two electronic switches24. The electronic switches24are respectively connected between the two secondary windings N2and two output ports14to provide power to loads. The control signal port13controls an on/off state of the electronic switches24.

If the loads enter a sleep state, the power device100opens the electronic switches124under control of the control signal port13to deny power to the loads. However, the input unit10and the power factor unit11are still connected to input power, causing power loss.

DETAILED DESCRIPTION

Before the embodiments are described, it is noted that similar elements in different embodiments are referred to same reference numbers.FIG. 2is a schematic diagram of a first embodiment of a power device200as disclosed. The power device200transforms input power Vs into power for output to loads connected thereto, and includes an input unit20, a power factor unit30, an output unit40, a power saving unit50, a control signal port60, and a standby power port62. In this embodiment, the power device200may transform alternating current (AC) power into direct current (DC) power for output to the loads.

The input unit20includes a filter C1, and a first rectifying circuit21connected to the filter C1to rectify the input power Vs. The input power Vs is first filtered by the filter C1, and then rectified by the first rectifying circuit21. In one embodiment, the filter C1may be a capacitor. The power factor unit30includes a power factor correction (PFC) circuit31to receive and correct the rectified power from the first rectifying circuit21.

The power saving unit50includes a first electronic switch51, a first diode D1and a single-direction switch D2. The first electronic switch51is connected between the first rectifying circuit21and the power factor correction circuit31. The rectified power from the first rectifying circuit21is also transmitted to the output unit40through the first diode D1before being transmitted to the first electronic switch51. That is, the first diode D1is connected between the first rectifying circuit21and the output unit40. The single-direction switch D2is connected to the power factor unit30and the output unit40to block current from the output unit40to the power factor unit30. Thus, unnecessary power loss, especially power loss in a standby state of the power device200, is avoided. In one embodiment, the single-direction switch D2may be a diode, and is connected between the power factor unit30and the output unit40. It is understood that the single-direction switch D2may use other switch elements, such as transistors.

The output unit40includes an output transformer T1having a primary winding N1and at least one secondary winding N2, a power switch41, a pulse width modulation (PWM) circuit42, at least one second rectifying circuit43, and at least one second electronic switch44. The numbers of the second rectifying circuit43, the second electronic switch44, and the secondary winding N2are the same. In one embodiment, the numbers of the second rectifying circuits43, the second electronic switches44, and the secondary windings N2are two.

The primary winding N1of the output transformer T1couples to the power factor unit to receive the corrected power, and the secondary winding N2is connected to the second rectifying circuit43. The power switch41is connected to the primary winding N1, and is under control of the PWM circuit42. The second rectifying circuit43performs half-wave rectification on output power from the secondary winding N2. In one embodiment, the second rectifying circuit40may use a second diode D3.

The second electronic switch44is connected between the second rectifying circuit43and output ports63, and provides power to the loads connected to the output ports63. The second electronic switch44and the first electronic switch51may be transistors, metal-oxide semiconductors (MOS), or relays. In one embodiment, the numbers of the output ports63and the second electronic switches44are also the same. The output unit40further includes a first filtering capacitor C2connected to the primary winding N1. In one embodiment, the first filtering capacitor C2filters the output power from the power factor circuit30into direct current (DC) power.

The control signal port61receives control signals from a control device outside of the power device200, and controls an on/off state of the first electronic switch51.

The standby power port62receives output power from one of the second rectifying circuits43, and provides necessary power to the loads to maintain a sleep state and awaken the power device200and the loads quickly. In one embodiment, the standby power port62is connected between the secondary winding N2and the second electronic switch44.

In one embodiment, the power factor unit30further includes a coil L, a second electronic switch32, a third diode D4, a resistor R1and a capacitor C3. The coil L receives the rectified power from the first rectifying circuit21, and outputs power to the output unit40via rectifying by the third diode D4and filtering by the capacitor C3. In one embodiment, the output power from the capacitor C3may be DC power with a high voltage value, such as, 380V. The third electronic switch32is connected between an output end of the coil L and ground, and is controlled by the power factor correction circuit31. In one embodiment, the third electronic switch32may be grounded through a resistor. The resistor R1feeds back power rectified by the third diode D4to the power factor correction circuit31. In one embodiment, the coil L may be a primary winding of a transformer that has a secondary winding providing power to the power factor correction circuit31. In one embodiment, the output unit40transforms the output power from the capacitor C3into DC power with a low voltage value, such as, 5V.

When in the standby state, the power device200not only denies power to the loads, but also opens the first electronic switch51by the control signals from the control signal port61to deny power to the power factor unit30, and only provides minimal power to the output unit40through the first diode D1. Thus, power loss of the power device200in the standby state is further reduced to achieve strict standby power loss standards and comply with power saving criteria.

FIG. 3is a schematic diagram of a second embodiment of the power device200as disclosed, differing from that of the first embodiment in connections of the first electronic switch51and the first diode D1of the second embodiment. The first electronic switch51is connected to an input end of the first rectifying circuit21, and receives the input power Vs. The first diode D1receives the input power Vs and provides power to the output unit40. Thus, when the power device200is in the standby state, and the first electronic switch51is kept open, power loss of the power factor unit30as well as of the input unit20is avoided, which results in lower standby power than that of the first embodiment.

FIG. 4is a schematic diagram of a third embodiment of the power device200as disclosed, differing from that of the first embodiment in that the power device200of the third embodiment further includes a third rectifying circuit70receiving the input power Vs and connected to the standby power port62.

FIG. 5is a schematic diagram of a fourth embodiment of the power device200as disclosed, differing from that of the first embodiment in that the output transformer T1of the output unit40has three secondary windings N2and that the second rectifying circuit43rectifies output power from the three secondary windings N2, one of which is provided to the standby power port62.

FIG. 6is a schematic diagram of a fifth embodiment of the power device200as disclosed, differing from that of the first embodiment in a structure of the power factor unit30and a connection between the power factor unit30and the single-direction switch D2. In this embodiment, the power factor unit30includes the power factor correction circuit31, the coil L, the third electronic switch32, the third diode D4, a fourth diode D5, the resistor R1, the capacitor C3and a second filtering capacitor C4. Functions and connections of the coil L, the third diode D4, the capacitor C3, and the third electronic switch32of the fifth embodiment are similar to those of the first embodiment, therefore descriptions are omitted here.

An anode of the fourth diode D5is connected to the output end of the coil L, and a cathode of the fourth diode D5is connected to the power factor correction circuit31through the resistor R1. The fourth diode D5provides power substantially the same as power rectified by the third diode D4to the resistor R1to feed back to the power factor correction circuit31. One end of the second filtering capacitor C4is connected between the fourth diode D5and the resistor R1, and the other end of the second filtering capacitor C4is grounded. The single-direction switch D2is connected between the third diode D4and the fourth diode D5, in this disclosure, especially between the cathodes of the third diode D4and the fourth diode D5, and an anode of the single-direction switch D2is connected to the cathode of the fourth diode D5.

In the fifth embodiment, the second filtering capacitor C4has a low capacitance value, and the first filtering capacitor C2with a large capacitance value of the first embodiment may be omitted. Thus, cost of the power device200of the fifth embodiment is reduced.

It is noted that the designs of the standby power port62of the third embodiment and the fourth embodiment can also be used in the power device200of the second embodiment, and that the designs of the power factor unit30and the power saving unit50of the fifth embodiment can also be used in the power device200of the second embodiment.