CN112865050A

CN112865050A - Adaptive regulation surge current limiter

Info

Publication number: CN112865050A
Application number: CN201911182884.6A
Authority: CN
Inventors: 陈鹤鸣
Original assignee: Suzhou Meanwell Technology Co ltd; MEAN WELL (GUANGZHOU) ELECTRONICS CO Ltd
Current assignee: Suzhou Meanwell Technology Co ltd; MEAN WELL (GUANGZHOU) ELECTRONICS CO Ltd
Priority date: 2019-11-27
Filing date: 2019-11-27
Publication date: 2021-05-28
Anticipated expiration: 2039-11-27
Also published as: CN112865050B

Abstract

The invention relates to an adaptive surge current limiter which is composed of at least one current-limiting resistor, a voltage detection unit, an adjusting unit, a relay control unit and a relay. Particularly, in the case that the starting time of a power supply unit including the inrush current limiter is less than the pull-in time of the relay, the adjusting unit outputs an adjusting signal to the relay control unit according to whether a resistance voltage detected by the voltage detecting unit exceeds a threshold value, so that the relay control unit controls the relay to perform a pull-in switching operation in advance. On the contrary, under the condition that the starting time of the power supply device is longer than the attraction time of the relay, the relay control unit can control the relay to execute the attraction switching action after a delay time. In short, the inrush current limiter of the invention can adaptively adjust the pull-in time of the relay according to different starting times of different power supply devices.

Description

Adaptive regulation surge current limiter

Technical Field

The present invention relates to Power supply devices, and more particularly, to an inrush current limiter coupled between an ac Power source and a main Power Supply Unit (PSU). Particularly, the inrush current limiter can adaptively adjust the pull-in time of an internal relay thereof according to the specific starting time of the collocated PSU.

Background

The input terminal of a Switching Mode Power Supply (SMPS) is usually connected with a large capacitor (Bulk capacitor) for performing a filtering rectification process on the input ac Power together with a bridge rectifier. However, the large capacitor is equivalent to a short circuit at the moment of starting the switching power supply, and thus generates a large surge current. Therefore, it is conventional practice to suppress this inrush current using Negative Temperature Coefficient (NTC) resistors, however this simple approach has many disadvantages including: (1) the current limiting effect reduces the conversion efficiency of the switching power supply by the ambient temperature and (2) the power loss of the NTC resistor.

In view of this, an inrush current limiter comprising a control unit is proposed. Fig. 1 is a block diagram of an inrush current limiter of the prior art. As shown in fig. 1, a conventional inrush current limiter 1' includes: a current limiting unit 11 ', a relay 12' and a control unit 13 ', wherein the current limiting unit 11' includes at least one current limiting resistor and has two electrical terminals for respectively coupling between a Live wire input terminal Lin 'and a Live wire output terminal Lout'. On the other hand, the relay 12 ' has three electrical connections, and two of the three electrical connections are respectively coupled to the live input Lin ' and the live output Lout '. Furthermore, the control unit 13 'has two electrical connection terminals, one of the two electrical connection terminals is coupled between a neutral wire input terminal Nin' and a neutral wire output terminal Nout ', and the other electrical connection terminal is coupled to the last set of electrical connection terminals of the relay 12'.

More specifically, when a Power Supply Unit (PSU) having the inrush current limiter 1 ' shown in fig. 1 is operated, if the start time (Setup time) of the Power supply unit is less than the pull-in time of the relay 12 ', the Power supply unit is started many times before the relay 12 ' performs the pull-in operation, so that a large current continuously flows through the current limiting resistor, thereby causing the temperature of the current limiting resistor to be too high, and finally causing the fuse of the Power supply unit to be blown.

As can be seen from the above description, the existing inrush current limiter 1 'including the control unit 13' still has room for further improvement. In view of the above, the inventors of the present invention have made intensive studies and finally have developed an adaptive inrush current limiter according to the present invention.

Disclosure of Invention

The invention mainly aims to provide an adaptive regulation surge current limiter, which comprises: at least one current limiting resistor, a voltage detecting unit, an adjusting unit, a relay control unit, and a relay. Particularly, in the case that the starting time of a power supply unit including the inrush current limiter is less than the pull-in time of the relay, the adjusting unit outputs an adjusting signal to the relay control unit according to whether a resistance voltage detected by the voltage detecting unit exceeds a threshold value, so that the relay control unit controls the relay to perform a pull-in switching operation in advance. On the contrary, under the condition that the starting time of the power supply device is longer than the attraction time of the relay, the relay control unit can control the relay to execute the attraction switching action after a delay time. In short, the inrush current limiter of the invention can adaptively adjust the pull-in time of the relay according to different starting times of different power supply devices.

It is worth emphasizing that, since the inrush current limiter of the present invention can adaptively adjust the pull-in time of the relay according to different start times of different power devices, the temperature of the current limiting resistor can be prevented from being too high due to the power devices being started for multiple times, so as to protect the fuse from being fused at high temperature.

To achieve the above objective, the present invention provides an embodiment of the adaptive regulation inrush current limiter, which is applied to a power conversion circuit, wherein the power conversion circuit has a power input stage unit, and the power input stage unit is coupled to a live line input terminal, a live line output terminal, a zero line input terminal, and a zero line output terminal; wherein the adaptive regulation inrush current limiter is coupled between the hot line output terminal and the power input stage unit, and includes:

at least one current limiting resistor having two electrical terminals coupled to the power input stage unit and the live line output terminal, respectively;

a voltage detection unit coupled to the two electrical terminals of the current-limiting resistor for detecting a resistor voltage across the current-limiting resistor;

the adjusting unit is coupled with the power input stage unit and the voltage detecting unit and used for receiving a voltage detecting signal transmitted by the voltage detecting unit;

a relay control unit coupled to the adjusting unit, so that the adjusting unit is coupled between the relay control unit and the power input stage unit; and

a relay, including a coil and a single-pole double-throw switch, wherein two electrical terminals of the relay are coupled with the relay control unit, the single-pole double-throw switch has a first pin, a second pin and a null pin, the first pin is coupled between one of the electrical terminals of the current-limiting resistor and the power input stage unit, and the second pin is coupled with the live wire output terminal;

wherein, after the power conversion circuit is started and the resistance voltage exceeds a critical value, the adjusting unit transmits an adjusting signal to the relay control unit after receiving the voltage detection signal, so that the relay control unit provides a driving signal to the coil of the relay, thereby controlling the single-pole double-throw switch to perform a switching-on and switching-off operation (switch-off);

after the power conversion circuit is started and the voltage of the resistor does not exceed the critical value, the relay control unit provides the driving signal to the coil of the relay after a delay time, so that the single-pole double-throw switch is controlled to execute the pull-in switching action.

In an embodiment, the power conversion circuit is included in a power supply, a power converter, or an LED driving power device.

In one possible embodiment, the adaptive regulation inrush current limiter of the present invention has an average limiting cycle (limiting cycles) and the average limiting cycle is 3 cycles/min.

In the embodiment of the adaptive control inrush current limiter of the present invention, the delay time is 300 ms.

In an embodiment of the adaptive regulation inrush current limiter of the present invention, the voltage detection unit includes:

a light emitting diode, having a cathode terminal and an anode terminal coupled to the two electrical terminals of the current limiting resistor respectively; and

and the input resistor is coupled between the anode end of the light-emitting diode and the current-limiting resistor.

In the embodiment of the adaptive regulation inrush current limiter of the present invention, a first isolation diode has a cathode terminal and an anode terminal respectively coupled between the cathode terminal of the light emitting diode and the current limiting resistor, and at least one zener diode is coupled between the current limiting resistor and the input resistor for providing an overvoltage limiting protection.

In an embodiment of the adaptive regulation inrush current limiter of the present invention, the relay control unit includes:

a first resistor, having one end coupled to the power input stage unit;

a delay capacitor, one end of which is coupled to the other end of the first resistor;

a first Zener diode having a cathode terminal coupled between the first resistor and the delay capacitor;

a second resistor, one end of which is coupled to an anode end of the Zener diode;

a third resistor, one end of which is coupled to the other end of the second resistor;

a first Bipolar Junction Transistor (BJT) having a base terminal coupled between the second resistor and the third resistor, and the other terminal of the third resistor, the other terminal of the delay capacitor, and an emitter terminal of the first BJT being coupled to the power input stage unit;

a second BJT having a base terminal coupled to a collector terminal of the first BJT;

a fourth resistor, both ends of which are coupled between the first resistor and a base terminal of the second bipolar junction transistor, and both ends of which are coupled between an emitter terminal and the base terminal of the second bipolar junction transistor; and

a second zener diode having a cathode terminal and an anode terminal coupled between a collector terminal of the second bjt and the emitter terminal of the first bjt.

In an embodiment of the adaptive regulation inrush current limiter of the present invention, the regulation unit includes:

a light sensitive transistor having a light receiving end, a collector end and an emitter end, wherein the light receiving end is coupled to a light signal emitted by the light emitting diode, and the emitter end is coupled between the first Zener diode and the delay capacitor; and

a fifth resistor, one end of which is coupled to the collector terminal of the phototransistor and the other end of which is coupled between the first resistor and the fourth resistor.

In the embodiment of the adaptive control inrush current limiter of the present invention, the first bipolar junction transistor is an NPN-type bipolar junction transistor, and the second bipolar junction transistor is a PNP-type bipolar junction transistor.

In the foregoing embodiment of the adaptive trimming inrush current limiter of the present invention, the photo transistor and the light emitting diode are integrated into an optocoupler.

Drawings

Fig. 1 shows a block diagram of an inrush current limiter of the prior art;

fig. 2 shows a block diagram of an adaptive regulation inrush current limiter according to the present invention;

FIG. 3 shows a first circuit topology block diagram of the adaptive regulation inrush current limiter of the present invention;

FIG. 4 shows a block diagram of a power input stage unit and a circuit topology structure diagram of the adaptive regulation inrush current limiter of the present invention; and

fig. 5 shows a second circuit topology block diagram of the adaptive regulated inrush current limiter of the present invention.

The main symbols in the figures illustrate:

1 surge current limiter with adaptive regulation

11 current limiting resistor

12 Voltage detection Unit

13 adjustment unit

14 Relay control unit

15 Relay

151 coil

152 single-pole double-throw switch

2 power supply input stage unit

21 voltage-limiting protection unit

22 large capacitance

23 plug-in resistance unit

24 step-down current limiting unit

25 bridge rectifier unit

26 voltage stabilizing and filtering unit

3 fuse unit

4 current limiting resistance unit

Lin live wire input end

Lout live wire output end

Nin zero line input end

Output end of Nout zero line

D1 first isolation diode

R8, R18 current limiting resistor

R10 input resistor

R14 first resistor

R17 second resistor

R20 third resistor

R16 fourth resistor

R15 fifth resistor

LD light-emitting diode

LT phototransistor

C3 time delay capacitor

Q1 first bipolar junction transistor

Q2 second bipolar junction transistor

ZD4, ZD5 zener diode

ZD7 first zener diode

ZD1 second zener diode

1C optical coupler

1C1 first connection end

1C2 second connection end

1C3 third connecting end

Fourth connecting end of 1C4

1' inrush current limiter

11' Current limiting Unit

12' relay

13' control unit

Lin' live wire input end

Lout' live wire output end

Nin' zero line input end

Nout' zero line output end

Detailed Description

In order to more clearly describe the adaptive regulation inrush current limiter proposed in the present invention, a preferred embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

Fig. 2 shows a block diagram of a circuit of an adaptive regulation inrush current limiter of the present invention, and fig. 3 shows a first circuit topology structure diagram of the adaptive regulation inrush current limiter of the present invention. As shown in fig. 2 and fig. 3, the adaptive inrush current limiter 1 of the present invention is applied to a power conversion circuit, wherein the power conversion circuit is included in a power supply, a power converter, or an LED driving power device and has a power input stage unit 2. More specifically, the power input stage unit 2 is coupled to a live input terminal Lin, a live output terminal Lout, a neutral input terminal Nin, and a neutral output terminal Nout. It should be understood that the live input Lin and the neutral input Nin are used to couple with the mains (i.e., alternating current). The power input stage unit 2 rectifies, filters and stabilizes the ac power, and then provides a dc power to the back-end circuit unit through the live line output terminal Lout and the neutral line output terminal Nout.

Fig. 2 and fig. 3 also show that the power conversion circuit has a fuse unit 3 and a current-limiting resistance unit 4, wherein the fuse unit 3 includes at least one fuse, and the current-limiting resistance unit 4 includes at least one current-limiting resistance. As shown in fig. 2 and fig. 3, the adaptive inrush current limiter 1 is coupled between the live line output terminal Lout and the power input stage unit 2, and mainly includes: at least one current limiting resistor 11 (fig. 3 shows current limiting resistors R8 and R18), a voltage detecting unit 12, a (relay pull-in time) adjusting unit 13, a relay control unit 14, and a relay 15. As shown in fig. 2, the at least one current-limiting resistor 11 has two electrical terminals respectively coupled to the power input stage unit 2 and the hot output terminal Lout, and the voltage detection unit 12 is coupled to the two electrical terminals of the current-limiting resistor 11 for detecting a resistor voltage across the current-limiting resistor 11. More specifically, the adjusting unit 13 is coupled to the power input stage unit 2 and the voltage detecting unit 12, and is configured to receive a voltage detecting signal transmitted by the voltage detecting unit 12. On the other hand, the relay control unit 14 is coupled to the adjusting unit 13, such that the adjusting unit 13 is coupled between the relay control unit 14 and the power input stage unit 2.

As described above, the relay 15 includes a coil 151 and a single-pole double-throw switch 152, both electrical terminals of which are coupled to the relay control unit 14; the single-pole double-throw switch 152 has a first pin, a second pin and a dummy pin, wherein the first pin is coupled between one of the electrical terminals of the current-limiting resistor 11 and the power input stage unit 2, and the second pin is coupled to the live line output terminal Lout. According to the design of the present invention, after the power conversion circuit including the adaptive inrush current limiter 1 of the present invention is started, if the voltage detection unit 12 detects that the resistance voltage exceeds a threshold value, the adjustment unit 13 will transmit an adjustment signal to the relay control unit 14 after receiving the voltage detection signal, so that the relay control unit 14 provides a driving signal to the coil 151 of the relay 15, thereby controlling the single-pole double-throw switch 152 to perform a switching-on (switch-off) operation.

In short, if the start time (Set up time) of the power supply device including the power conversion circuit is less than the pull-in time of the relay 15, the power supply device is started many times before the relay 15 performs the pull-in switching operation, so that the resistance voltage across the current limiting resistor 11 exceeds a threshold value. At this time, after receiving the voltage detection signal transmitted by the voltage detection unit 12, the adjustment unit 13 outputs an adjustment signal to the relay control unit 14, so that the relay control unit 14 controls the single-pole double-throw switch 152 to perform the pull-in switching operation in advance. On the contrary, after the power device including the power conversion circuit is started and the resistance voltage does not exceed the threshold value, the relay control unit 14 provides the driving signal to the coil 151 of the relay 15 after a delay time, so as to control the single-pole double-throw switch 152 to perform the pull-in switching operation. In short, in the case that the start time (Set up time) of the power supply device is greater than the pull-in time of the relay 15, the relay control unit 14 controls the relay 15 to perform the pull-in switching operation after a delay time of 300ms elapses.

With continuing reference to fig. 2 and fig. 3, and with further reference to fig. 4, a block diagram of the power input stage unit 2 and a circuit topology structure diagram of the adaptive regulation inrush current limiter of the present invention are shown. In one embodiment, a power input stage unit 2 of a power conversion circuit included in a power device generally includes: a voltage limiting protection unit 21, a large capacitor (bulk capacitor)22, a plug-in resistor unit 23, a voltage reducing and current limiting unit 24, a bridge rectifier unit 25, and a voltage stabilizing and filtering unit 26. In the case of referring to fig. 3 and fig. 4, it should be understood that the voltage detecting unit 12 mainly includes a light emitting diode LD and an input resistor R10; the led LD has a cathode terminal and an anode terminal respectively coupled to the two electrical terminals of the current limiting resistor 11, and the input resistor R10 is coupled between the anode terminal of the led LD and the current limiting resistor 11. In addition, a first isolation diode D1 has an anode terminal and a cathode terminal respectively coupled between the cathode terminal of the led LD and the current limiting resistor 11, and at least one zener diode (ZD4, ZD5) coupled between the current limiting resistor 11 and the input resistor R10 for providing an over-voltage limiting protection.

In particular, the relay control unit 14 is formed by a first resistor R14, a delay capacitor C3, a first zener diode ZD7, a second resistor R17, a third resistor R20, a first Bipolar Junction Transistor (BJT) Q1, a second Bipolar junction transistor Q2, a fourth resistor R16, and a second zener diode ZD 1. As shown in fig. 3 and 4, one end of the first resistor R14 is coupled to the power input stage unit 2, one end of the delay capacitor C3 is coupled to the other end of the first resistor R14, and a cathode end of the first zener diode ZD7 is coupled between the first resistor R14 and the delay capacitor C3. In addition, one end of the second resistor R17 is coupled to an anode end of the zener diode ZD7, and one end of the third resistor R20 is coupled to the other end of the second resistor R17. On the other hand, the first Bipolar Junction Transistor (BJT) Q1 is an NPN-type bipolar junction transistor, and has a base terminal coupled between the second resistor R17 and the third resistor R20. It is noted that the other terminal of the third resistor R20, the other terminal of the delay capacitor C3, and an emitter terminal of the first bjt Q1 are all coupled to the power input stage unit 2.

As described above, the second bjt Q2 is a PNP-type bjt, and has a base terminal coupled to a collector terminal of the first bjt Q1. The fourth resistor R16 is coupled between the first resistor R14 and a collector of the first bjt Q1 at two ends, and the fourth resistor R16 is coupled between an emitter and a base of the second bjt Q2 at two ends. In addition, fig. 3 and 4 also show that the second zener diode ZD1 is coupled between a cathode terminal and an anode terminal of the second bjt Q2 and the emitter terminal of the first bjt Q1.

According to the design of the present invention, the adjusting unit 13 includes a phototransistor LT and a fifth resistor R15. The photo transistor LT has a light receiving terminal coupled to a light signal (i.e., the voltage detection signal) emitted from the light emitting diode LD, a collector terminal coupled between the first zener diode ZD7 and the delay capacitor C3, and an emitter terminal. Also, one end of the fifth resistor R15 is coupled to the collector of the phototransistor LT, and the other end is coupled between the first resistor R14 and the fourth resistor R16.

Fig. 2 and 3 distinguish the respective circuit units or modules according to circuit functions so that the voltage detection unit 12 and the adjustment unit 13 look like two independent circuit units. However, in a possible embodiment, the light emitting diode LD in the voltage detection unit 12 and the phototransistor LT in the adjustment unit 13 may be integrated into an optocoupler. Fig. 5 shows a second circuit topology block diagram of the adaptive regulated inrush current limiter of the present invention. In fig. 5, the voltage detecting unit 12 also includes a light emitting diode LD and an input resistor R10, and the adjusting unit 13 also includes a phototransistor LT and a fifth resistor R15. It is noted that the led LD and the phototransistor LT are integrated into an optical coupler 1C, and the optical coupler 1C has a first connection terminal 1C1, a second connection terminal 1C2, a third connection terminal 1C3, and a fourth connection terminal 1C 4.

With careful reference to fig. 5, it should be understood that the optocoupler 1C is coupled with its first connection terminal 1C1 to the anode terminal of the first isolation diode D1 and with its second connection terminal 1C2 to the input resistor R10, so that the light emitting diode LD and the input resistor R10 of the optocoupler 1C together form the voltage detecting unit 12 of the adaptive regulation inrush current limiter 1 of the present invention. On the other hand, the optocoupler 1C is also coupled with its third connection 1C3 to the fifth resistor R15 and with its fourth connection 1C4 to the relay control unit 14 between the first zener diode ZD7 and the delay capacitor C3. It is arranged such that the phototransistor LT and the fifth resistor R15 of the optocoupler 1C together form the adjusting unit 13 of the adaptively adjusted inrush current limiter 1 according to the invention.

Thus, the basic structure and technical features of an adaptive regulation inrush current limiter 1 disclosed in the present invention have been fully and clearly described above; moreover, it can be seen from the above that the present invention has the following advantages:

(1) the invention uses at least a current limiting resistor 11, a voltage detecting unit 12, an adjusting unit 13, a relay control unit 14 and a relay 15 to form the surge current limiter 1 with self-adaptive adjustment. In the case that the start time of a power supply unit including the inrush current limiter 1 is shorter than the pull-in time of the relay 15, the adjusting unit 13 outputs an adjusting signal to the relay control unit 14 according to whether a resistance voltage detected by the voltage detecting unit 12 exceeds a threshold value, so that the relay control unit 14 controls the relay to perform an attraction switching operation in advance. On the contrary, in case that the start time of the power supply apparatus is longer than the pull-in time of the relay 15, the relay control unit 14 controls the relay 15 to perform the pull-in switching action after a delay time elapses. In short, the inrush current limiter 1 of the present invention can adaptively adjust the pull-in time of the relay 15 according to different start-up times of different power devices.

(2) As described above, since the inrush current limiter 1 of the present invention can adaptively adjust the pull-in time of the relay 15 according to different start times of different power devices, the temperature of the current limiting resistor 11 can be prevented from being too high due to multiple starts of the power device, so as to protect the fuse from being fused at high temperature.

It should be emphasized that the above detailed description is specific to possible embodiments of the invention, but this is not to be taken as limiting the scope of the invention, and all equivalent implementations or modifications that do not depart from the technical spirit of the invention are intended to be included within the scope of the invention.

Claims

1. A surge current limiter of self-adaptive regulation is applied to a power conversion circuit, the power conversion circuit is provided with a power input stage unit, and the power input stage unit is coupled with a live wire input end, a live wire output end, a zero line input end and a zero line output end; wherein the adaptive regulation inrush current limiter is coupled between the hot line output terminal and the power input stage unit, and includes:

wherein, after the power conversion circuit is started and the resistance voltage exceeds a critical value, the adjusting unit transmits an adjusting signal to the relay control unit after receiving the voltage detection signal, so that the relay control unit provides a driving signal to the coil of the relay, thereby controlling the single-pole double-throw switch to perform a suction switching action;

2. The adaptive-regulation inrush current limiter of claim 1, wherein the power conversion circuit is included in a power supply, a power converter, or an LED driving power device.

3. The adaptively adjusted inrush current limiter of claim 1, wherein the delay time is 300 ms.

4. The adaptively adjusted inrush current limiter of claim 1, having an average limit cycle frequency, wherein the average limit cycle frequency is 3 cycles/min.

5. The adaptively adjusted inrush current limiter of claim 1, wherein the voltage detection unit comprises:

6. The adaptive regulation inrush current limiter of claim 5, wherein an anode terminal and a cathode terminal of a first isolation diode are coupled between the cathode terminal of the light emitting diode and the current limiting resistor, respectively, and at least one zener diode is coupled between the current limiting resistor and the input resistor for providing an overvoltage limiting protection.

7. An adaptively adjusted inrush current limiter according to claim 5, characterized in that the relay control unit comprises:

a first resistor, having one end coupled to the power input stage unit;

a first BJT having a base terminal coupled between the second resistor and the third resistor, and the other terminal of the third resistor, the other terminal of the delay capacitor, and an emitter terminal of the first BJT being coupled to the power input stage unit;

a fourth resistor, both ends of which are coupled between the first resistor and a collector terminal of the second bipolar junction transistor, and both ends of which are coupled between an emitter terminal and the base terminal of the second bipolar junction transistor; and

8. The adaptively adjusted inrush current limiter of claim 7, wherein the adjustment unit comprises:

9. The adaptive-tuning inrush current limiter of claim 7, wherein the first bipolar junction transistor is an NPN bipolar junction transistor and the second bipolar junction transistor is a PNP bipolar junction transistor.

10. The adaptively adjusted inrush current limiter of claim 8, wherein the phototransistor and the light emitting diode are integrated into an optocoupler.