CN201418030Y - Power supply with surge current prevention - Google Patents

Abstract

A power supply device capable of preventing surge current is applied to a parallel power bus. The power supply with surge current prevention function comprises: a filter capacitor and a current control unit. The current control unit is electrically connected to the filter capacitor. The current control unit controls a charging current flowing through the filter capacitor to avoid a surge current from being generated on the parallel power bus.

Description

Power supply with protection against inrush current

technical field

The utility model relates to a power supply device, in particular to a power supply device capable of preventing surge current.

Background technique

Power supply is the most important part of all electronic systems. Without power supply, the machine cannot be operated. Currently, many electronic systems are designed to have a reserve margin, and not only have one set of power supplies, but also have multiple sets of power supplies. These power supplies are connected to the electronic system through a parallel power bus to operate in parallel to ensure that the electronic system always receives sufficient power to work.

When a single power supply fails, the entire electronic system will not be shut down for replacement with a new power supply due to the failure of the single power supply, so hot swap maintenance is required. And newer power supplies will have fairly large uncharged filter capacitors on the output. When a new power supply is replaced, the uncharged filter capacitor will draw an inrush current from the parallel power bus, which will cause a considerable instantaneous voltage drop on the parallel power bus (as shown in Figure 5 Shown), making the power supply unstable.

On the output of the power supply, if there is no large filter capacitor, as shown in Figure 3, the output current ripple will be quite large. On the output end of the power supply, if there is a large filter capacitor, as shown in Figure 4 (300A in the figure is the filter capacitor), the output current ripple will be relatively small. However, there will be a surge current when the above-mentioned new power supply is just replaced, and the voltage on the parallel power bus will have a considerable instantaneous voltage drop, making the power supply unstable.

Utility model content

The technical problem to be solved by the utility model is that the prior art utility model provides a power supply device capable of preventing surge current.

In order to achieve the above purpose, the utility model provides a power supply with surge current prevention, which is applied to a parallel power bus. The power supply with surge current prevention includes: a filter capacitor and a current control unit for controlling the charging current flowing through the filter capacitor. The current control unit is electrically connected to the filter capacitor. The current control unit controls a charging current flowing through the filter capacitor to avoid generating a surge current on the parallel power bus.

The above-mentioned power supply with surge current prevention is characterized in that the current control unit further includes:

a power switch unit electrically connected to the filter capacitor; and

A control unit for controlling the charging current flowing through the filter capacitor, the control unit is electrically connected to the power switch unit and controls the power switch unit to avoid the surge current on the parallel power bus.

In the above-mentioned power supply with surge current prevention, the control unit further includes:

A first resistor, one end of the first resistor is electrically connected to the filter capacitor, and the other end is electrically connected to the power switch unit;

a second resistor, one end of the second resistor is electrically connected to the power switch unit, and the other end is electrically connected to ground; and

A first capacitor, one end of the first capacitor is electrically connected to the power switch unit, and the other end is electrically connected to the ground.

In the above-mentioned power supply with surge current prevention, the power switch unit is a metal oxide semiconductor field effect transistor.

In the above-mentioned power supply with surge current prevention, the current control unit is a negative temperature coefficient thermistor.

In the above-mentioned power supply with surge current prevention, the filter capacitor is an electrolytic capacitor.

The aforementioned power supply with surge current prevention further includes an Oling switch electrically connected to the filter capacitor.

The aforementioned power supply with surge current prevention further includes a power circuit unit electrically connected to the filter capacitor.

The beneficial effects of the utility model are:

1. Because the inrush current does not occur, there will be no sparks to cause damage to the connection points on the parallel power bus and the power supply.

2. Because the surge current will not appear, a large filter capacitor can be designed at the output end of the power supply, and the output voltage and current ripple can be effectively suppressed.

3. Because the power switch unit can suppress the charging current flowing through the filter capacitor, there will be no large-scale instantaneous voltage drop on the power bus, and the power supply can be kept stable.

4. In the prior art, the electronic system behind the parallel power supply bus may cause an instantaneous voltage drop due to a sudden surge current, resulting in misjudgment by the electronic system. The electronic system will think that the power is insufficient and activate other backup power sources, or even perform a protective action of shutting down after wrongly storing data. In fact, it is only an instantaneous voltage drop caused by inrush current. The utility model does not have these misoperations because the surge current does not appear.

5. One of the means of eliminating the output current ripple in the prior art is to use the circuit before the OR'ing switch. That is, before the power flows to the electronic system through the OR’ing switch, the current ripple has been reduced first, so no large filter capacitors are placed on the output side of the power supply to avoid inrush current. However, the utility model can place a large filter capacitor on the output side of the power supply and avoid surge current. One of the benefits of a large filter capacitor is that it can offset the inductive characteristics of the OR'ing switch and other circuits, making voltage and current ripples smaller.

The utility model will be described in detail below in conjunction with the accompanying drawings and specific embodiments, but not as a limitation of the utility model.

Description of drawings

Fig. 1 is the block diagram (active type) of the power supply device with preventing inrush current of the present utility model;

Fig. 2 is a circuit diagram of an embodiment of the power supply with surge current prevention of the present invention;

Fig. 3 is a schematic diagram of no filter capacitor at the output end of the power supply;

FIG. 4 is a schematic diagram of a filter capacitor at the output end of the power supply;

FIG. 5 is a timing diagram of voltage versus current on the parallel power supply bus in the prior art;

Fig. 6 is the voltage-to-current sequence diagram of the utility model on the parallel power supply bus;

FIG. 7 is a block diagram of a power supply with surge current prevention of the present invention.

Among them, reference signs

10 Power supply with inrush current prevention

20 parallel power bus

100 power circuit unit

200 Ouling switch 300 filter capacitor

400 Current Control Unit

410 control unit

420 power switch unit

412 The first resistance

414 Second resistor

416 The first capacitor

20A parallel power bus

20B parallel power bus

300A filter capacitor

Detailed ways

Below in conjunction with accompanying drawing, structural principle and working principle of the present utility model are specifically described:

Please refer to FIG. 7 . FIG. 7 is a block diagram of a power supply with surge current prevention of the present invention. The power supply 10 with anti-inrush current of the present invention is applied to a parallel power bus 20 . The power supply 10 with surge current prevention includes: a power circuit unit 100 , an OR'ing switch 200 , a filter capacitor 300 and a current control unit 400 . The OR'ing switch 200 is electrically connected to the power circuit unit 100 and the filter capacitor 300 . The current control unit 400 is electrically connected to the filter capacitor 300 .

The power circuit unit 100 is a power circuit for converting DC/DC or AC/DC. The filter capacitor 300 is an electrolytic capacitor. The current control unit 400 controls a charging current flowing through the filter capacitor 300 to avoid generating a surge current on the parallel power bus 20 .

In consideration of safety, it is possible (but not limited) to connect a switch (OR'ing switch) in series with the output terminal of the power supply. That is, a power supply that can be used for hot swap (hot swap) can be connected in series with a switch (Oling switch) at the output end. Its purpose is to open the switch (Oling switch) after confirming that the power supply of the power supply is normal, so that the power flows out to supply the electronic system.

Wherein, the current control unit 400 can be active or passive. The following will be described in detail.

If the current control unit 400 is passive, it can be realized, for example, by a negative temperature coefficient thermistor (NTC Thermistor). The resistance value of a negative temperature coefficient thermistor (NTC Thermistor) decreases as the temperature rises. When the parallel power bus 20 is connected to the power supply of the present invention, the resistance of the current control unit 400 (NTC thermistor) is very large, and the charging current flowing through the filter capacitor 300 is very small. Then as the temperature rises gradually, the resistance value of the current control unit 400 (negative temperature coefficient thermistor) gradually decreases. Finally, the resistance value of the current control unit 400 (negative temperature coefficient thermistor) becomes extremely small, so that the filter capacitor 300 can perform an optimal filter function without generating the inrush current.

The active current control unit 400 will be described in detail below.

Please refer to FIG. 1 , which is a block diagram (active type) of a power supply with inrush current prevention of the present invention. The power supply 10 with anti-surge current of the present invention is applied to the parallel power bus 20 . The power supply 10 with anti-surge current of the present invention includes: a control unit 410, a power switch unit 420, the filter capacitor 300, the power circuit unit 100 and the OR'ing switch 200. The power switch unit 420 is electrically connected to the control unit 410 and the filter capacitor 300 . The OR'ing switch 200 is electrically connected to the power circuit unit 100 and the filter capacitor 300 . The power circuit unit 100 is a power circuit for converting DC/DC or AC/DC. The filter capacitor 300 is an electrolytic capacitor.

Firstly, when the power supply 10 with anti-surge current is connected to the parallel power bus 20 , the control unit 410 controls the power switch unit 420 to be in a cut-off state. Next, after the power supply 10 with anti-inrush current is completely connected to the parallel power bus 20, the control unit 410 controls the power switch unit 420 in the linear resistance working area, and controls the size of the linear resistance to control the current flow. The magnitude of the charging current through the filter capacitor 300 . The power switch unit 420 not only has a switching function, but also has a function of controlling the magnitude of the charging current flowing through the filter capacitor 300 . When the filter capacitor 300 is charged close to the voltage of the parallel power bus 20 , the control unit 410 controls the power switch unit 420 to be completely turned on, so that the filter capacitor 300 can perform an optimal filter function.

Please refer to FIG. 2 . FIG. 2 is a circuit diagram of an embodiment of the power supply with inrush current prevention of the present invention. The power supply 10 with anti-surge current of the present invention is applied to the parallel power bus 20 . The power supply 10 with surge current prevention of the present invention includes: the control unit 410 , the power switch unit 420 , the filter capacitor 300 , the power circuit unit 100 and the OR'ing switch 200 . The power switch unit 420 is electrically connected to the control unit 410 and the filter capacitor 300 . The OR'ing switch 200 is electrically connected to the power circuit unit 100 and the filter capacitor 300 . The power circuit unit 100 is a power circuit for converting DC/DC or AC/DC. The filter capacitor 300 is an electrolytic capacitor. The power switch unit 420 can be a metal oxide semiconductor field effect transistor (MOSFET).

The control unit 410 further includes: a first resistor 412 , a second resistor 414 and a first capacitor 416 . One end of the first resistor 412 is electrically connected to the filter capacitor 300 , and the other end is electrically connected to the power switch unit 420 . One end of the second resistor 414 is electrically connected to the power switch unit 420 , and the other end is electrically connected to the ground. One end of the first capacitor 416 is electrically connected to the power switch unit 420 , and the other end is electrically connected to the ground.

Firstly, when the power supply 10 with anti-surge current is connected to the parallel power bus 20, the OR'ing switch 200 is open and the power switch unit 420 is also in a cut-off state. Next, the parallel power bus 20 charges the first capacitor 416 through the first resistor 412 and the second resistor 414 . When the first capacitor 416 is charged to a voltage value, the power switch unit 420 will work in a linear resistance region. The parallel power bus 20 charges the filter capacitor 300 . And because the power switch unit 420 works in the linear resistance region, the charging current flowing through the filter capacitor 300 is limited below a limit value. The power switch unit 420 not only has a switching function, but also has a function of controlling the magnitude of the charging current flowing through the filter capacitor 300 . Finally, when the voltage on the first capacitor 416 enters to make the power switch unit 420 fully turned on, the filter capacitor 300 will work normally and play an optimal filter function.

Please refer to FIG. 5 . FIG. 5 is a timing diagram of voltage and current on the parallel power bus 20 when the power switch unit 420 does not control the filter capacitor 300 in the prior art. It can be seen that in the prior art, when the power supply is connected to the parallel power bus 20 , a large inrush current will be generated at the moment, thus causing a sudden drop in voltage and causing voltage instability. Please refer to FIG. 6 . FIG. 6 is a timing diagram of the voltage and current of the parallel power bus 20 when the power switch unit 420 of the present invention controls the filter capacitor 300 . It can be seen that the utility model does not generate a large surge current when the power supply is connected to the parallel power bus 20, so the voltage is still stable.

The focus of the present invention is: when a new power supply is connected to the parallel power bus 20, the current control unit 400 controls the charging current flowing through the filter capacitor 300, so that the filter capacitor 300 can be charged slowly to avoid The inrush current is generated on the parallel power bus 20 .

The utility model has the advantages of:

1. Because the inrush current does not occur, there will be no sparks to cause damage to the connection points on the parallel power bus and the power supply.

2. Because the surge current will not appear, a large filter capacitor can be designed at the output end of the power supply, and the output voltage and current ripple can be effectively suppressed.

3. Because the power switch unit can suppress the charging current flowing through the filter capacitor, there will be no large-scale instantaneous voltage drop on the power bus, and the power supply can be kept stable.

4. In the prior art, the electronic system behind the parallel power supply bus may cause an instantaneous voltage drop due to a sudden surge current, resulting in misjudgment by the electronic system. The electronic system will think that the power is insufficient and activate other backup power sources, or even perform a protective action of shutting down after wrongly storing data. In fact, it is only an instantaneous voltage drop caused by inrush current. The utility model does not have these misoperations because the surge current does not appear.

5. One of the means of eliminating the output current ripple in the prior art is to use the circuit before the OR'ing switch. That is, before the power flows to the electronic system through the OR’ing switch, the current ripple has been reduced first, so no large filter capacitors are placed on the output side of the power supply to avoid inrush current. However, the utility model can place a large filter capacitor on the output side of the power supply and avoid surge current. One of the benefits of a large filter capacitor is that it can offset the inductive characteristics of the OR'ing switch and other circuits, making voltage and current ripples smaller.

Of course, the utility model can also have other various embodiments, and those skilled in the art can make various corresponding changes and deformations according to the utility model without departing from the spirit and essence of the utility model, but These corresponding changes and deformations should all belong to the protection scope of the appended claims of the present utility model.

Claims (8)

1. A power supply with inrush current prevention, applied to a parallel power bus, characterized in that, the power supply with inrush current prevention includes: a filter capacitor; and A current control unit for controlling the charging current flowing through the filter capacitor is electrically connected to the filter capacitor. 2. The power supply with surge current prevention as claimed in claim 1, wherein said current control unit further comprises: a power switch unit electrically connected to the filter capacitor; and A control unit for controlling the charging current flowing through the filter capacitor, the control unit is electrically connected to the power switch unit and controls the power switch unit to avoid the surge current on the parallel power bus. 3. The power supply with surge current prevention as claimed in claim 2, wherein said control unit further comprises: A first resistor, one end of the first resistor is electrically connected to the filter capacitor, and the other end is electrically connected to the power switch unit; a second resistor, one end of the second resistor is electrically connected to the power switch unit, and the other end is electrically connected to ground; and A first capacitor, one end of the first capacitor is electrically connected to the power switch unit, and the other end is electrically connected to the ground. 4. The power supply with anti-surge current as claimed in claim 2, wherein the power switch unit is a metal oxide semiconductor field effect transistor. 5. The power supply with inrush current prevention as claimed in claim 1, wherein the current control unit is a negative temperature coefficient thermistor. 6. The power supply with inrush current prevention as claimed in claim 1, wherein the filter capacitor is an electrolytic capacitor. 7. The power supply with inrush current prevention as claimed in claim 1, further comprising an Oling switch electrically connected to the filter capacitor. 8. The power supply with inrush current prevention as claimed in claim 1, further comprising a power circuit unit electrically connected to the filter capacitor.

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