TW201605157A - Power supply - Google Patents

Abstract

The power supply of this invention includes a rectifier circuit, a boost converter, a first capacitor and a current limiting unit. The boost converter is connected to the rectifier circuit. The current limiting unit is connected to the boost converter and the first capacitor and acts to limit the inrush current at a start instant of the power supply. In addition, the current limiting unit also has an advantage of low-power consumption.

Description

Power Supplier

The present invention relates to a power supply, and more particularly to a power supply for limiting surge current.

The switching power supply usually has a short large current at the moment of starting up. This large current is called an inrush current. As shown in FIG. 1, the conventional power supply 90 is turned on, because the first capacitor C1 is an energy storage component, and the voltage change at the instant of power-on is low impedance. Therefore, at the instant of power-on, the input power is in a short time. A surge current is generated to charge the first capacitor C1 until the first capacitor C1 is fully charged, but the surge current may also damage a certain part of the power supply 90, and the part may be a rectifier or a booster Switch circuits or other.

In order to avoid the surge current, the conventional power supply 90 has a current limiting resistor 92 connected in series between the power input terminal V _I and the bridge rectifier 91 to reduce the input current and avoid excessive surge current. However, the current limiting resistor 92 connected in series at this location increases the power loss. Furthermore, the current limiting resistor 92 generally uses a thermistor with a negative temperature coefficient, so that the starting capability of the conventional power supply 90 is affected at low temperature startup.

Here, it is assumed that the efficiency of the conventional power supply 90 in FIG. 1 is 100%, the input voltage is 100 volts DC (V), the output voltage is 400 volts DC (V), the input current is 1 amp (A), and the output is The current is 0.25 amps (A) and the power is 100 watts (W), and the resistance of the current limiting resistor 92 is equal to 1 ohm. Thus, the power consumption of the current limiting resistor 92 is equal to 1 watt, that is, the square of the input current multiplied by the current limiting resistor. 92.

As shown in FIG. 2, in addition to the current limiting resistor 92, the conventional switching power supply 90 is connected in parallel with a switch 93 and a control circuit 94 of the switch 93. The switch 93 connected in parallel overcomes the aforementioned low temperature start. The problem, but this design also increases the complexity of the circuit and its cost.

In view of the above-mentioned deficiencies, the power supply of the present invention can provide lower power consumption than the prior art in addition to effectively suppressing surge current.

To achieve the above objective, the power supply of the present invention includes a rectifying circuit, a boosting switching circuit, a first capacitor, and a current limiting unit. The boost switching circuit is connected to the rectifier circuit. The current limiting unit is connected to the boost switching circuit and the first capacitor to limit a surge current of the power supply at the starting moment.

In this way, the power supply of the present invention increases the power supply by providing a current limiting unit between the boost switching circuit and the first capacitor to suppress the surge current and reduce the loss of the current limiting unit by the current limiting unit. Efficiency.

Detailed construction, features, assembly or use of the power supply provided by the present invention will be described in the detailed description of the subsequent embodiments. However, it should be understood by those of ordinary skill in the art that the present invention is not limited by the scope of the invention.

Hereinafter, the constituent members of the power supply of the present invention and the achievement of the efficacy will be described with reference to the preferred embodiments of the drawings. The components, components, and configurations of the power supplies in the various figures are only used to illustrate the technical features of the present invention, and are not intended to limit the present invention.

As shown in FIG. 3, the power supply 10 of the first embodiment of the present invention is used to supply power to a load, such as a DC conversion circuit 20. The power supply 10 includes a rectifier circuit 11, a boost switching circuit 13, a first capacitor C1, and a current limiting unit 15. The boosting switching circuit 13 is connected to the rectifier circuit 11, and the current limiting unit 15 is connected to the boosting switching circuit 13 and the first capacitor C1. The load 20 is connected in parallel with the capacitor C1.

The rectifier circuit 11 is for rectifying the AC power of the commercial power into a DC power source. The boost switching circuit 13 receives and processes the DC power source to generate a high frequency output voltage higher than the voltage level of the DC power source, wherein the output current of the boost switching circuit 13 is controlled to control the loss. In more detail, the smaller the output current, the smaller the loss.

Finally, the current limiting unit 15 receives the high frequency output voltage and limits the surge current generated at the instant of the power supply 10 startup. Thus, the power supply 10 of the present invention can achieve the purpose of suppressing surge current by providing the limiting unit 10, and the limiting unit 10 can consume less power and improve efficiency than the prior art current limiting resistor.

Referring again to FIG. 3, it can be seen from the prior art that the current limiting resistor of the conventional power supply consumes 1 watt of power. In this embodiment, the current limiting unit 15 has a resistor R. The resistor R is connected to the high voltage terminal of the boosting switching circuit 13 and one end of the first capacitor C1, and the low voltage terminal (ie, the ground terminal) of the boosting switching circuit 13 is connected to the other end of the first capacitor C1. If the resistance R is equal to 1 ohm and the input current is 1 amp under the same conditions, the boost switching circuit 13 has a large inductance 132, so that the current having ripple after rectification can be ignored, The boost switching circuit 13 operates in a continuous mode of operation. When the on-state period (D) of the diode 131 in the boost switching circuit 13 is equal to 0.25, the output current of the boost switching circuit 13 ( There are two components (such as formula one), one is the DC output current ( ), the DC output current is equal to 0.25 amps, and the other is the AC output current ( ), AC output current ( The approximate solution is calculated by Equation 1 to be 0.433 amps. Therefore, the resistance R of the current limiting unit 15 after conversion is about 0.25 watts. The calculated method is the resistance value multiplied by the square of the DC output current and the resistance value multiplied by The sum of the squares of the AC output current. Thus, the power consumption of the resistor R of the current limiting unit 15 is only 1/4 of that of the prior art current limiting resistor, so the power supply 10 of the present invention can effectively reduce power consumption and improve efficiency.

Formula one:

Formula 2:

In addition, at the moment when the power supply 10 is turned on, the resistance R of the current limiting unit 15 can provide an impedance to avoid the low impedance phenomenon of the first capacitor C1 at the instant of startup, and the power supply 10 generates an excessive surge current. . Therefore, the power supply 10 of the present invention can effectively suppress the surge current by the current limiting unit 15 at the time of starting up, and reduce the impedance consumption to improve the efficiency.

As shown in FIG. 4, the figure is a second embodiment of the present invention, and the resistor R of the current limiting unit 35 is connected to the low voltage terminal L and the first capacitor C1 of the boost switching circuit 33 as compared with the third embodiment. The ground terminal, that is, the resistor R of the current limiting unit 35 is located on the ground side of the entire power supply circuit, and H in the figure is the high voltage terminal of the boost switching circuit 33. As such, the second embodiment can also obtain the same effects and objects as those of the first embodiment, and thus will not be described again.

As shown in FIG. 5, the third embodiment of the present invention is substantially the same as the first and second embodiments except that the current limiting unit 45 further has a second capacitor C2. The second capacitor C2 is connected in parallel with the resistor R, and the capacitance value of the second capacitor C2 is smaller than the capacitance value of the first capacitor C1. Thus, at the moment when the power supply 40 is turned on, since the capacitance value of the second capacitor C2 is smaller than the capacitance value of the first capacitor C1, the second capacitor C2 can be fully charged as long as a small current, so the second capacitor C2 After being fully charged, the surge current that occurs afterwards can be ignored, that is, it does not affect the operation of the power supply 40.

As can be seen from the description of the first embodiment, the output current ( The composition can be divided into direct current ( And alternating current ( ). DC( When passing the current limiting unit 45, the DC current ( ) does not pass the second capacitor C2, so DC current ( ) only passes through the resistor R, so the DC current ( The resulting power loss is constant. Alternating current( When passing through the current limiting unit 45, the alternating current ( The resistor R and the second capacitor C2 are simultaneously passed, but since the resistor R and the second capacitor C2 are in a parallel relationship, the impedance of the two connected in parallel is smaller than the impedance of the only resistor R in the first and second embodiments. Therefore, the alternating current can be reduced ( The resulting power loss means that the power loss of the third embodiment is smaller and more efficient than the first and second embodiments.

As shown in FIG. 6, the figure is a fourth embodiment of the present invention, and compared with the fifth figure, the resistance R of the current limiting unit 55 and the second capacitor C2 connected in parallel with the resistor R are connected to the boosting switching. The low voltage terminal L of the circuit 53 and the ground terminal of the first capacitor C1, that is, the resistor R and the second capacitor C2 of the current limiting unit 55 are located on the ground side of the entire power supply 50. The capacitance value of the second capacitor C2 is smaller than the capacitance value of the first capacitor C1. As such, the fourth embodiment can also obtain the same effects and objects as the third embodiment, and thus will not be described again.

As shown in FIG. 7, the figure is a fifth embodiment of the present invention. Compared with the first embodiment, the current limiting unit 65 of the fifth embodiment further has a second capacitor C2, and the second capacitor C2 is boosted. The switching circuit 63 is connected in parallel and is located at the front end of the resistor R. The capacitance value of the second capacitor C2 is smaller than the capacitance value of the first capacitor C1. Thus, when the power supply 60 is turned on, the second capacitor C2 can be fully charged as long as the current is small, and the continuously occurring surge current can be ignored. That is, the operation of the power supply 60 is not affected by the large capacitance of the first capacitor C1. Moreover, the configuration of the current limiting unit 65 also consumes a small amount of power to improve the efficiency of the power supply.

As shown in FIG. 8, the figure is a sixth embodiment of the present invention. Compared with the fifth embodiment, the sixth embodiment connects the resistor R to the low voltage terminal L of the boost switching circuit 73 and the first capacitor. The grounding end of the C1, that is, the resistor R of the current limiting unit 75 is located on the ground side of the entire circuit. Thus, the sixth embodiment can also obtain the same effects and objects as those of the fifth embodiment, and details are not described herein again.

As shown in Fig. 9, the figure is a seventh embodiment of the present invention. Compared with the fifth embodiment, the current limiting unit 85 further has a third capacitor C3. The third capacitor C3 is connected in parallel with the resistor R. The capacitance of the third capacitor C3 is smaller than the capacitance of the first capacitor C1. As such, the power supply 80 of the seventh embodiment can also suppress the surge current by the second and third capacitors C2 and C3, and only consume a small amount of power compared with the prior art to improve the starting efficiency.

In summary, the power supply of the present invention provides a current limiting unit between the boost switching circuit and the first capacitor to suppress the surge current and reduce the loss of the current limiting unit by the current limiting unit. Improve the efficiency of the power supply.

Finally, it is emphasized that the constituent elements disclosed in the foregoing embodiments are merely illustrative and are not intended to limit the scope of the present invention, and alternatives or variations of other equivalent elements should also be the scope of the patent application of the present application. Covered.

10, 30, 40, 50, 60, 70, 80‧‧‧ power supplies
11, 41, 51, 61‧‧ ‧ rectifier circuit
13, 33, 43, 53, 63, 73, 83‧‧‧ boost switching circuit
131‧‧‧ diode
132‧‧‧Inductance
15, 35, 45, 55, 65, 75, 85‧‧‧ current limiting units
20‧‧‧DC conversion circuit
90‧‧‧Traditional power supply
91‧‧‧Bridge rectifier
92‧‧‧ Current limiting resistor
93‧‧‧ switch
94‧‧‧Control circuit
C1‧‧‧first capacitor
C2‧‧‧second capacitor
C3‧‧‧ third capacitor
R‧‧‧resistance
L‧‧‧Low end
H‧‧‧High end
V _I ‧‧‧ input
‧‧‧Output current

Figures 1 and 2 are schematic views of a conventional power supply, respectively. Figure 3 is a schematic view of a first embodiment of the power supply of the present invention. Fig. 4 is a schematic view showing a second embodiment of the power supply of the present invention. Fig. 5 is a schematic view showing a third embodiment of the power supply of the present invention. Fig. 6 is a schematic view showing a fourth embodiment of the power supply of the present invention. Fig. 7 is a schematic view showing a fifth embodiment of the power supply of the present invention. Figure 8 is a schematic view of a sixth embodiment of the power supply of the present invention. Figure 9 is a schematic view showing a seventh embodiment of the power supply of the present invention.

10‧‧‧Power supply

11‧‧‧Rectifier circuit

13‧‧‧Boost switching circuit

131‧‧‧ diode

132‧‧‧Inductance

15‧‧‧ Current limiting unit

20‧‧‧DC conversion circuit

C1‧‧‧first capacitor

R‧‧‧resistance

I _o ‧‧‧Output current

Claims (8)

A power supply device includes: a rectifying circuit; a boosting switching circuit connected to the rectifying circuit; a first capacitor; and a current limiting unit connecting the boosting switching circuit and the first capacitor to Limit the surge current of the power supply at the moment of startup. The power supply device of claim 1, wherein the boosting switching circuit has a high voltage end and a low voltage end, the first capacitor has two terminals, and the current limiting unit has a resistor, the current limiting unit The resistor is connected to the high voltage end of the boosting switching circuit and one end of the first capacitor, and the low voltage end of the boosting switching circuit is connected to the other end of the first capacitor. The power supply device of claim 2, wherein the current limiting unit further has a second capacitor connected in parallel with the resistor, and the capacitance value of the second capacitor is smaller than a capacitance value of the first capacitor. The power supply device of claim 2, wherein the current limiting unit further has a second capacitor connected in parallel with the boosting switching circuit and located at a front end of the resistor, the second capacitor The capacitance value is less than the capacitance value of the first capacitor. The power supply device of claim 4, wherein the current limiting unit further has a third capacitor connected in parallel with the resistor, and the capacitance value of the third capacitor is smaller than a capacitance value of the first capacitor. The power supply device of claim 1, wherein the boosting switching circuit has a high voltage end and a low voltage end, the first capacitor has two terminals, and the current limiting unit has a resistor, the boosting type The high voltage end of the switching circuit is connected to one end of the first capacitor, and the resistance of the current limiting unit is connected to the low voltage end of the boosting switching circuit and the other end of the first capacitor. The power supply device of claim 6, wherein the current limiting unit further has a second capacitor connected in parallel with the resistor, and a capacitance value of the second capacitor is smaller than a capacitance value of the first capacitor. The power supply device of claim 6, wherein the current limiting unit further has a second capacitor connected in parallel with the boosting switching circuit and located at a front end of the resistor.