阅读说明：本技术 一种串联功率模块的自动合闸旁路保护装置及控制方法 (Automatic closing bypass protection device of series power module and control method ) 是由 谢晔源 盛晓东 王宇 叶晗 段军 于 2020-12-31 设计创作，主要内容包括：本申请提供一种串联功率模块的自动合闸旁路保护装置及控制方法。所述装置包括第二直流电容支路、合闸触发单元、分闸触发单元和失电保护单元,合闸触发单元、第二直流电容支路与电源单元并联；旁路开关合闸线圈和触发元件串联后与第一直流电容并联,旁路开关合闸线圈闭合控制功率模块的旁路开关合闸；失电保护单元包括并联在触发元件两端的失电保护开关,测到电源单元输出电压降到一定值时,控制失电保护开关闭合,使旁路开关合闸线圈得电,功率模块的旁路开关闭合。(The application provides an automatic closing bypass protection device of a series power module and a control method. The device comprises a second direct current capacitor branch, a closing trigger unit, an opening trigger unit and a power loss protection unit, wherein the closing trigger unit and the second direct current capacitor branch are connected with a power supply unit in parallel; the bypass switch closing coil is connected in series with the trigger element and then connected in parallel with the first direct current capacitor, and the bypass switch closing coil closes a bypass switch of the control power module; the power-off protection unit comprises power-off protection switches connected in parallel at two ends of the trigger element, and when the output voltage of the power supply unit is detected to be reduced to a certain value, the power-off protection switches are controlled to be closed, so that a closing coil of the bypass switch is electrified, and the bypass switch of the power module is closed.)

1. An automatic closing bypass protection device of series power modules, comprising:

a power supply unit including a power supply;

the second direct current capacitor branch circuit is connected to two ends of the power supply unit in parallel and comprises a second direct current capacitor;

a closing trigger unit connected in parallel at both ends of the second dc capacitor branch, the closing trigger unit including:

a first direct current capacitor, a negative electrode of which is connected with a negative electrode of the power supply unit;

the anode of the diode is connected with the anode of the second direct current capacitor branch, and the cathode of the diode is connected with the anode of the first direct current capacitor;

the bypass switch closing coil and the trigger element are connected in series and then connected in parallel with the first direct current capacitor to control the closing of the bypass switch of the power module;

the switching-off trigger unit is connected to two ends of the power supply in parallel and controls the switching-off of a bypass switch of the power module;

the control unit controls the on or off of the trigger element;

and the power-off protection unit comprises power-off protection switches connected in parallel at two ends of the trigger element, and when the output voltage of the power supply unit is detected to be reduced to a certain value, the power-off protection switches are controlled to be closed, so that a closing coil of the bypass switch is electrified, and the bypass switch of the power module is closed.

2. The apparatus of claim 1, wherein the power loss protection unit further comprises:

and the power loss detection circuit is used for controlling the power loss protection switch to be closed when detecting that the output voltage of the power supply unit is reduced to a certain value, so that the closing coil of the bypass switch is electrified, and the bypass switch of the power module is closed.

3. The apparatus of claim 2, further comprising:

the first parallel resistor is connected to two ends of the first direct-current capacitor in parallel;

the second parallel resistor is connected to two ends of the second direct current capacitor branch in parallel;

the capacitance value of the second direct current capacitor is smaller than that of the first direct current capacitor; or the resistance value of the second parallel resistor is smaller than that of the first parallel resistor; or the product of the capacitance value of the second direct current capacitor and the resistance value of the second parallel resistor is smaller than the product of the capacitance value of the first direct current capacitor and the resistance value of the first parallel resistor.

4. The apparatus of claim 1, the power supply unit further comprising:

and the anti-reverse diode is connected between the anode of the power supply and the output end of the power supply unit in series.

5. The apparatus of claim 3, wherein the power loss protection switch is a normally open node of a first relay, the power loss detection circuit comprising a first auxiliary circuit connected in parallel across the diode, wherein the first auxiliary loop comprises:

the coil of the first relay, both ends of the said coil draw out as the first auxiliary loop carry-out terminal; or

The coil and the resistor of the first relay are connected in series and then led out to serve as the output end of the first auxiliary loop; or

The coil of first relay and at least two divider resistance that establish ties each other, the coil of first relay connects in parallel at the both ends of arbitrary divider resistance, and the series connection is drawn forth the back and is regarded as first auxiliary circuit output.

6. The apparatus of claim 5, wherein the second DC capacitive branch further comprises:

the normally closed node of the first relay is connected with the second direct current capacitor in series; or

And the discharging branch circuit is connected in parallel at two ends of the second direct current capacitor and comprises a normally open node and a discharging resistor of the first relay which are connected in series.

7. The apparatus of claim 3, wherein the power-loss protection switch comprises a normally closed node of a second relay and a normally open node of a third relay connected in series; the power loss detection circuit comprises a second auxiliary loop and a third auxiliary loop, the output end of the second auxiliary loop is connected with two ends of a second direct current capacitor in parallel, the output end of the third auxiliary loop is connected with two ends of a first direct current capacitor in parallel, and the Nth auxiliary loop comprises:

two ends of the coil of the Nth relay are led out to be used as the output end of the Nth auxiliary loop; or

The Nth auxiliary loop comprises a coil and a resistor of an Nth relay, and the coil and the resistor of the Nth relay are connected in series and then led out to serve as an output end of the Nth auxiliary loop; or

The nth auxiliary loop comprises a coil of an nth relay and at least two voltage dividing resistors which are connected in series, the coil of the nth relay is connected to two ends of any voltage dividing resistor in parallel, the nth relay is connected in series and led out to serve as an nth auxiliary loop output end, and N is 2 or 3.

8. The apparatus of claim 7, wherein an operating voltage of the coil of the second relay is lower than an operating voltage of the coil of the third relay.

9. The apparatus of claim 7, wherein the coil of the second relay and the coil of the third relay have equal operating voltages, and the coil of the second relay has a higher voltage when the voltages across the second auxiliary loop and the third auxiliary loop are equal.

10. The apparatus of claim 1, further comprising:

and the charging resistor is connected between the cathode of the diode and the anode of the first direct current capacitor in series.

11. The apparatus of claim 1, wherein the power-loss protection switch and the trigger element each comprise a power semiconductor device comprising at least one of a thyristor, an IGBT, and a MOSFET.

12. A method of controlling an automatic closing bypass protection device of a series power module according to any of claims 1 to 11, comprising:

the power supply unit is started, and the voltage of the first direct current capacitor gradually rises;

when the power supply unit loses power, the power-losing protection switch is closed, the first direct current capacitor discharges, the bypass switch closing coil is electrified, and the bypass switch is closed.

13. The method of claim 12, wherein the power loss protection switch is a normally open node of a first relay, and wherein the power loss detection circuit includes a first auxiliary circuit connected in parallel across the diode, the method comprising:

the power supply unit is started, and the voltage of the first direct current capacitor and the voltage of the second direct current capacitor gradually rise;

when the power supply unit loses power, the voltage of the second direct current capacitor is rapidly reduced;

when the difference between the voltage of the first direct current capacitor and the voltage of the second direct current capacitor is larger than the action voltage of the first relay coil, the first relay coil acts, and a normally open node of the first relay is closed;

the first direct current capacitor discharges, the closing coil of the bypass switch is electrified, and the bypass switch is closed.

14. The method of claim 12, wherein the power loss protection switch comprises a normally closed node of a second relay and a normally open node of a third relay connected in series, the power loss detection circuit comprises a second auxiliary loop and a third auxiliary loop, an output end of the second auxiliary loop is connected in parallel across a second direct current capacitor, and an output end of the third auxiliary loop is connected in parallel across a first direct current capacitor, the method comprises:

when the power supply unit is started, the voltage of the first direct current capacitor and the voltage of the second direct current capacitor gradually rise, the coil of the second relay is electrified to act, and the normally closed node of the second relay is disconnected;

when the power supply unit is powered off, the voltage of the second direct current capacitor is rapidly reduced, the coil of the second relay is powered off, and the normally closed node of the second relay is closed;

the first direct current capacitor discharges, the third relay coil is electrified to act, the normally open node of the third relay is closed, the bypass switch closing coil is electrified, and the bypass switch is closed.

Technical Field

The application relates to the technical field of high-power electronic converter, in particular to an automatic closing bypass protection device and a control method for a series power module.

Background

In the technical field of high-capacity high-power electronic converter, in order to improve the transmission capability of a converter, a chain type multi-level technology is generally adopted, and a plurality of power modules are connected in series.

Due to the fact that the power modules are connected in series, when one power module fails, other power modules are not adversely affected. Therefore, the bypass switch is connected in parallel to the ac side of the power module, and when the power module fails, the bypass switch is quickly closed to bypass the failure.

The modules in the distributed power flow controller or the voltage sag treatment device are connected in series in a circuit, the two ends of the alternating current side of the series module are connected in parallel with the bypass switch, the function of a fault bypass can be achieved, when the power transmission line is powered off and maintained, the bypass switch can be closed firstly or kept in a closed state all the time, and after the system is normally powered on, the control system is normally started and then the starting process is executed.

If the bypass switch of the series power module is not closed while the line is live, there is a potential risk for the following reasons: the series power module usually gets energy through the current transformer who connects in series in the circuit, consequently the series power module can't get energy when the circuit is uncharged, and the heavy current flows into power module rapidly when the circuit is electrified, and the capacitor voltage rises rapidly, and the power is established and needs time, and control system does not come to start to react, and the bypass switch is not in time to close a floodgate, and direct current voltage will rise always, and power module has the excessive pressure risk. Therefore, it is safest to ensure that the bypass switch is in a closed state in case of power loss of the power supply.

The bypass switch is required to be closed quickly when the power supply is powered off due to line power failure or power failure in the operation process. The prior bypass technology mainly focuses on bypass reliability and bypass speed, and does not consider the operation characteristics of the switch under the condition of no power supply.

Disclosure of Invention

The embodiment of the application provides an automatic closing bypass protection device of a series power module, which comprises a power supply unit, a second direct current capacitor branch, a closing trigger unit, a separating trigger unit, a control unit and a power loss protection unit, wherein the power supply unit comprises a power supply; the second direct current capacitor branch is connected to two ends of the power supply unit in parallel, and comprises a second direct current capacitor; the switching-on trigger unit is connected to two ends of the second direct current capacitor branch in parallel, the switching-on trigger unit comprises a first direct current capacitor, a diode, a bypass switch switching-on coil and a trigger element, and the negative electrode of the first direct current capacitor is connected with the negative electrode of the power supply unit; the anode of the diode is connected with the anode of the second direct current capacitor branch, and the cathode of the diode is connected with the anode of the first direct current capacitor; the bypass switch closing coil is connected with the trigger element in series and then connected with the first direct current capacitor in parallel to control the closing of the bypass switch of the power module; the opening trigger unit is connected to two ends of the power supply in parallel and controls the opening of a bypass switch of the power module; the control unit controls the on or off of the trigger element; the power-off protection unit comprises power-off protection switches connected in parallel at two ends of the trigger element, and when the output voltage of the power supply unit is detected to be reduced to a certain value, the power-off protection switches are controlled to be closed, so that a closing coil of the bypass switch is electrified, and the bypass switch of the power module is closed.

According to some embodiments, the power loss protection unit further includes a power loss detection circuit, and when the power loss detection circuit detects that the output voltage of the power supply unit drops to a certain value, the power loss protection switch is controlled to be closed, so that a closing coil of the bypass switch is powered on, and the bypass switch of the power module is closed.

According to some embodiments, the apparatus further comprises a first parallel resistance and a second parallel resistance, the first parallel resistance being connected in parallel across the first direct current capacitor; the second parallel resistor is connected to two ends of the second direct current capacitor branch in parallel; the capacitance value of the second direct current capacitor is smaller than that of the first direct current capacitor; or the resistance value of the second parallel resistor is smaller than that of the first parallel resistor; or the product of the capacitance value of the second direct current capacitor and the resistance value of the second parallel resistor is smaller than the product of the capacitance value of the first direct current capacitor and the resistance value of the first parallel resistor.

According to some embodiments, the apparatus further comprises a reverse diode connected in series between the positive pole of the power supply and the power supply unit output.

According to some embodiments, the power loss protection switch is a normally open node of a first relay, and the power loss detection circuit comprises a first auxiliary circuit connected in parallel to two ends of the diode, wherein the first auxiliary circuit comprises a coil of the first relay, and two ends of the coil are led out to serve as a first auxiliary circuit output end; or a coil and a resistor of the first relay are connected in series and then led out to serve as the output end of the first auxiliary loop; or the coil of the first relay and at least two voltage-dividing resistors which are mutually connected in series are connected in parallel at two ends of any voltage-dividing resistor, and the coil of the first relay is connected in series and then taken as the output end of the first auxiliary loop after being led out.

According to some embodiments, the second dc capacitor branch further includes a normally closed node of the first relay or a discharging branch, the normally closed node of the first relay is connected in series with the second dc capacitor, the discharging branch is connected in parallel across the second dc capacitor, and the discharging branch includes a normally open node of the first relay and a discharging resistor connected in series.

According to some embodiments, the power loss protection switch comprises a normally closed node of a second relay and a normally open node of a third relay connected in series; the power loss detection circuit comprises a second auxiliary loop and a third auxiliary loop, the output end of the second auxiliary loop is connected with two ends of a second direct current capacitor in parallel, the output end of the third auxiliary loop is connected with two ends of a first direct current capacitor in parallel, and the Nth auxiliary loop comprises: two ends of the coil of the Nth relay are led out to be used as the output end of the Nth auxiliary loop; or the Nth auxiliary loop comprises a coil and a resistor of an Nth relay, and the coil and the resistor of the Nth relay are connected in series and then led out to serve as an output end of the Nth auxiliary loop; or the Nth auxiliary loop comprises a coil of an Nth relay and at least two voltage-dividing resistors which are mutually connected in series, the coil of the Nth relay is connected in parallel at two ends of any voltage-dividing resistor and is connected in series to be led out to be used as an output end of the Nth auxiliary loop, and N is 2 or 3.

According to some embodiments, an operating voltage of the coil of the second relay is lower than an operating voltage of the coil of the third relay.

According to some embodiments, the coil of the second relay and the coil of the third relay have equal operating voltages, and when voltages across the second auxiliary loop and the third auxiliary loop are equal, the coil of the second relay is divided into higher voltages.

According to some embodiments, the apparatus further comprises a charging resistor connected in series between the cathode of the diode and the anode of the first direct current capacitor.

According to some embodiments, the power loss protection switch and the trigger element each comprise a power semiconductor device comprising at least one of a thyristor, an IGBT, and a MOSFET.

The embodiment of the present application further provides a control method for the automatic closing bypass protection device of the series power module, including: the power supply unit is started, and the voltage of the first direct current capacitor gradually rises; when the power supply unit loses power, the power-losing protection switch is closed, the first direct current capacitor discharges, the bypass switch closing coil is electrified, and the bypass switch is closed.

According to some embodiments, when the power loss protection switch is a normally open node of a first relay and the power loss detection circuit includes a first auxiliary circuit connected in parallel across the diode, the method comprises: the power supply unit is started, and the voltage of the first direct current capacitor and the voltage of the second direct current capacitor gradually rise; when the power supply unit loses power, the voltage of the second direct current capacitor is rapidly reduced; when the difference between the voltage of the first direct current capacitor and the voltage of the second direct current capacitor is larger than the action voltage of the first relay coil, the first relay coil acts, and a normally open node of the first relay is closed; the first direct current capacitor discharges, the closing coil of the bypass switch is electrified, and the bypass switch is closed.

According to some embodiments, the power loss protection switch comprises a normally closed node of a second relay and a normally open node of a third relay which are connected in series, the power loss detection circuit comprises a second auxiliary loop and a third auxiliary loop, an output end of the second auxiliary loop is connected in parallel to two ends of a second direct current capacitor, and an output end of the third auxiliary loop is connected in parallel to two ends of a first direct current capacitor, and the method comprises: when the power supply unit is started, the voltage of the first direct current capacitor and the voltage of the second direct current capacitor gradually rise, the coil of the second relay is electrified to act, and the normally closed node of the second relay is disconnected; when the power supply unit is powered off, the voltage of the second direct current capacitor is rapidly reduced, the coil of the second relay is powered off, and the normally closed node of the second relay is closed; the first direct current capacitor discharges, the third relay coil is electrified to act, the normally open node of the third relay is closed, the bypass switch closing coil is electrified, and the bypass switch is closed.

According to the technical scheme provided by the embodiment of the application, the bypass switch can be reliably closed when the power supply unit is powered off, and the system reliability is greatly improved.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.

Fig. 1 is a schematic diagram of an automatic closing bypass protection device of a series power module according to an embodiment of the present disclosure.

Fig. 2 is a schematic flowchart of a control method of an automatic closing bypass protection device of a series power module according to an embodiment of the present application.

Fig. 3 is a second schematic diagram of an automatic closing bypass protection device of a series power module according to an embodiment of the present disclosure.

Fig. 4 is a third schematic diagram of an automatic closing bypass protection device of a series power module according to an embodiment of the present application.

Fig. 5 is a fourth schematic diagram of an automatic closing bypass protection device of a series power module according to an embodiment of the present application.

Fig. 6 is a schematic diagram of an implementation of an auxiliary loop of an automatic closing bypass protection device of a series power module according to an embodiment of the present application.

Fig. 7 is a second schematic diagram of an implementation of an auxiliary circuit of an automatic closing bypass protection device of a series power module according to an embodiment of the present application.

Fig. 8 is a third schematic diagram of an implementation of an auxiliary circuit of an automatic closing bypass protection device of a series power module according to an embodiment of the present application.

Fig. 9 is a fifth schematic diagram of an automatic closing bypass protection device of a series power module according to an embodiment of the present application.

Fig. 10 is a second flowchart illustrating a control method of an automatic closing bypass protection device of a series power module according to an embodiment of the present application.

Fig. 11 is a sixth schematic view of an automatic closing bypass protection device of a series power module according to an embodiment of the present application.

Fig. 12 is a seventh schematic diagram of an automatic closing bypass protection device of a series power module according to an embodiment of the present application.

Fig. 13 is a third schematic flowchart of a control method of an automatic closing bypass protection device of a series power module according to an embodiment of the present application.

Detailed Description

The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are some, but not all, embodiments of the present application. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

It will be understood that the terms "comprises" and/or "comprising," when used in this specification and claims, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

Fig. 1 is a schematic diagram of an automatic closing bypass protection device of a series power module according to an embodiment of the present disclosure.

The automatic closing bypass protection device of the series power module comprises a power supply unit 2, a second direct current capacitor branch 7, a closing trigger unit 1, an opening trigger unit 8, a power-off protection unit 3 and a control unit 6.

The power supply unit 2 includes a power supply. A second dc capacitive branch 7 is connected in parallel across the power supply unit 2, the second dc capacitive branch 7 comprising a second dc capacitor C2.

The closing trigger unit 1 is connected in parallel to two ends of the second direct current capacitor branch 7. The closing trigger unit 1 includes a first dc capacitor C1, a diode 4, a bypass switch closing coil L1, and a trigger element 5. The negative electrode of the first direct-current capacitor C1 is connected to the negative electrode of the power supply unit 2. The anode of the diode 4 is connected to the anode of the second dc capacitor branch 7, and the cathode of the diode 4 is connected to the anode of the first dc capacitor C1. And a bypass switch closing coil L1 is connected with the trigger element 5 in series and then is connected with a first direct current capacitor C1 in parallel, so that the closing of a bypass switch KM of the power module is controlled.

The opening trigger unit 8 is connected in parallel at two ends of the power supply and controls the opening of the bypass switch KM of the power module. The control unit 6 controls the switching on or off of the triggering element 5. The power-off protection unit 3 comprises a power-off protection switch K1 connected in parallel at two ends of the trigger element 5, and when the output voltage of the power supply unit 2 is detected to be reduced to a certain value, the power-off protection switch K1 is controlled to be closed, so that a closing coil L1 of the bypass switch is powered on, and a bypass switch KM of the power module is closed.

The anode of the power supply unit 2 is connected to the anode of the diode 4, and the cathode of the power supply unit 2 is connected to the cathode of the first dc capacitor C1.

According to some embodiments, the opening trigger unit 8 comprises a second anti-reverse diode D2, a third direct current capacitor C3, a shunt resistor 13, a third parallel resistor R3, an opening coil F1 and a trigger element 15. The anode of the second anti-reverse diode D2 is connected with the anode of the power supply, the cathode of the second anti-reverse diode D2 is connected with one end of the shunt resistor 13, the other end of the shunt resistor 13 is connected with the anode of the third direct current capacitor C3, and the cathode of the third direct current capacitor C3 is connected with the cathode of the power supply unit 2. The third parallel resistor R3 is connected in parallel at two ends of the third direct current capacitor C3, and the opening coil F1 and the trigger element 15 are connected in series and then connected in parallel at two ends of the third direct current capacitor C3.

When the switch is normally switched on, the control unit triggering element 5 is closed, the first direct current capacitor C1 discharges electricity, the switch-on coil L1 is electrified, and the bypass switch KM is closed.

When the switch is normally opened, the control unit triggering element 15 is closed, the third direct current capacitor C3 discharges, the switch-on coil F1 is electrified, and the bypass switch KM is opened.

Optionally, the device further comprises an anti-reverse diode D2, the positive electrode of the power supply is connected with the positive electrode of the anti-reverse diode D2, the negative electrode of the power supply unit 2 is connected with the negative electrode of the first direct current capacitor C1, and the negative electrode of the anti-reverse diode D2 is connected with the positive electrode of the second direct current capacitor branch 7.

The power-off protection unit 3 comprises a power-off protection switch K1 connected in parallel at two ends of the trigger element 5, and when the output voltage of the power supply unit 2 is detected to be reduced to a certain value, the power-off protection switch K1 is controlled to be closed, so that a closing coil L1 of the bypass switch is powered on, and a bypass switch KM of the power module is closed. The control unit 6 controls the switching on or off of the triggering element 5.

The power loss protection switch K1 and the trigger element 5 each include a power semiconductor device, and the power semiconductor device includes at least one of a thyristor, an IGBT, and a MOSFET, but not limited thereto.

Optionally, the power loss protection unit 3 further includes a power loss detection circuit, and when the power loss detection circuit detects that the output voltage of the power supply unit drops to a certain value, the power loss protection switch K1 is controlled to be closed, so that the bypass switch closing coil L1 is powered on, and the bypass switch KM of the power module is closed.

Optionally, the apparatus further includes a charging resistor 11 connected in series between the cathode of the diode 4 and the anode of the first dc capacitor C1, for shunting the charging current of the first dc capacitor C1.

Optionally, if the power loss protection switch K1 includes a normally open node of the first relay, the second dc capacitor branch 7 further includes a normally closed node of the first relay, and is connected in series with the second dc capacitor C2. When the power loss protection is carried out, the second direct current capacitor C2 is disconnected with a subsequent circuit.

According to some embodiments, a control method of an automatic closing bypass protection device of a series power module includes the following processes, as shown in fig. 2.

In S110, the power supply unit 2 is started, and the voltage of the first dc capacitor C1 gradually rises.

In S120, when the power supply unit 2 loses power, the power-loss protection switch K1 is closed, the first dc capacitor C1 discharges, the bypass switch closing coil L1 gets powered, and the bypass switch KM is closed.

Fig. 3 is a second schematic diagram of an automatic closing bypass protection device of a series power module according to an embodiment of the present disclosure.

As shown in fig. 3, in addition to the embodiment of fig. 1, the automatic closing bypass protection device of the series power module further includes a first parallel resistor R1 and a second parallel resistor R2. The first parallel resistor R1 is connected in parallel across the first dc capacitor C1. The second parallel resistor R2 is connected in parallel across the second dc capacitor C2.

When the second dc capacitor C2 does not have the second parallel resistor R2, the capacitance of the second dc capacitor C2 is smaller than that of the first dc capacitor C1.

With the first parallel resistor and the second parallel resistor, the resistance of the second parallel resistor R2 is smaller than that of the first parallel resistor R1, i.e., R2< R1. Or the product of the capacitance value of the second direct current capacitor C2 and the resistance value of the second parallel resistor R2 is smaller than the product of the capacitance value of the first direct current capacitor C1 and the resistance value of the first parallel resistor R1, namely R2 × C2< R1 × C1.

Optionally, if the power-off protection switch K1 includes the normally open node of the first relay, the second dc capacitor branch 7 further includes the normally open node of the first relay, and is connected in series with the discharge resistor. When the power-off protection is performed, the discharge resistor is turned on, and the second dc capacitor C2 is disconnected from the subsequent circuit, as shown in fig. 4.

Fig. 5 is a fourth schematic diagram of an automatic closing bypass protection device of a series power module according to an embodiment of the present application.

As shown in fig. 5, based on the embodiment of fig. 3, the power loss protection switch of the automatic closing bypass protection device of the series power module is a normally open node of the first relay K1, and the power loss detection circuit includes a first auxiliary circuit H1 connected in parallel to two ends of a diode, where the first auxiliary circuit H1 has three implementation manners.

In a first implementation, the first auxiliary circuit H1 includes a coil of the first relay K1, and two ends of the coil are led out as the first auxiliary circuit output end, as shown in fig. 6.

In a second implementation manner, the first auxiliary circuit H1 includes a coil and a resistor of the first relay K1, and the coil and the resistor of the first relay K1 are connected in series and then led out as a first auxiliary circuit output end, as shown in fig. 7. Fig. 9 is a schematic diagram of an automatic closing bypass protection device of a series power module.

In a third implementation manner, the first auxiliary loop H1 includes a coil of the first relay K1 and at least two voltage dividing resistors connected in series with each other, and the coil of the first relay K1 is connected in parallel to two ends of any voltage dividing resistor and connected in series to be taken as the output end of the first auxiliary loop, as shown in fig. 8.

According to some embodiments, when the automatic closing bypass protection device of the series power module comprises a second direct current capacitor C2, the power loss protection switch is a normally open node of a first relay K1, and the power loss detection circuit comprises a first auxiliary circuit H1 connected in parallel across a diode, the method comprises the following process, as shown in fig. 10.

In S210, the power supply unit 2 is turned on, and the voltages of the first dc capacitor C1 and the second dc capacitor C2 gradually increase.

The voltage of the first direct current capacitor and the voltage of the second direct current capacitor continue to rise, the voltages at two ends of the coil of the first relay are kept equal, and the normally open node of the first relay is kept disconnected. When the relay normally operates, the first relay coil is in a power-off state, and the power-off protection switch is in a breaking position.

In S220, when the power supply unit 2 loses power, the voltage of the second dc capacitor C2 rapidly drops.

At this time, since the capacitance value of the first dc capacitor C1 is greater than that of the second dc capacitor C2, or when there is a first parallel resistor and a second parallel resistor, the resistance value of the second parallel resistor R2 is smaller than that of the first parallel resistor R1, that is, R2< R1. Or the product of the capacitance value of the second direct current capacitor C2 and the resistance value of the second parallel resistor R2 is smaller than the product of the capacitance value of the first direct current capacitor C1 and the resistance value of the first parallel resistor R1, namely R2 × C2< R1 × C1. Causing the voltage of the first dc capacitor C1 to drop more slowly.

In S230, when the difference between the voltage of the first dc capacitor C1 and the voltage of the second dc capacitor C2 is greater than the voltage for operating the coil of the first relay K1, the coil of the first relay K1 is operated, and the normally open node of the first relay is closed.

In S240, the first dc capacitor C1 discharges, the bypass switch closing coil L1 is energized, and the bypass switch KM is closed.

Fig. 11 is a sixth schematic view of an automatic closing bypass protection device of a series power module according to an embodiment of the present application.

As shown in fig. 11, based on the embodiment of fig. 3, the power-off protection switch of the automatic closing bypass protection device of the series power module includes a normally closed node of the second relay K2 and a normally open node of the third relay K3 which are connected in series. The power loss detection circuit comprises a second auxiliary loop H2 and a third auxiliary loop H3, wherein the output end of the second auxiliary loop H2 is connected in parallel with two ends of a second direct current capacitor C2, and the output end of the third auxiliary loop H3 is connected in parallel with two ends of a first direct current capacitor C1. The nth auxiliary loop has three implementation modes, wherein N is 2 or 3.

In a first implementation manner, the nth auxiliary loop includes a coil of the nth relay, and two ends of the coil are led out to serve as output ends of the nth auxiliary loop, as shown in fig. 6.

In a second implementation manner, the nth auxiliary circuit includes a coil and a resistor of the nth relay, and the coil of the nth relay is connected in series with the resistor and then led out as an output end of the nth auxiliary circuit, as shown in fig. 7. Fig. 12 is a schematic diagram of an automatic closing bypass protection device of a series power module.

In a third implementation manner, the nth auxiliary loop includes a coil of the nth relay and at least two voltage dividing resistors connected in series, the coil of the nth relay is connected in parallel to two ends of any voltage dividing resistor, and the N-th auxiliary loop is connected in series and led out to serve as an output end of the nth auxiliary loop, as shown in fig. 8.

Alternatively, the operating voltage of the coil of the second relay K2 is lower than the operating voltage of the coil of the third relay K3. When the power supply unit normally operates, the second relay K2 can be ensured to operate before the third relay K3, and the power-off protection switch can be kept in an off state.

Alternatively, the coil of the second relay K2 and the coil of the third relay are equal in operating voltage, and when the voltages at both ends of the second auxiliary circuit and the third auxiliary circuit are equal, the voltage divided by the coil of the second relay K2 is higher, so that it can be ensured that the second relay K2 operates earlier than the third relay K3 to maintain the off state of the power loss protection switch when the power supply unit is operating normally. The voltage divided by the coil is usually adjusted by adjusting the resistance of the voltage dividing resistor.

According to some embodiments, when the automatic closing bypass protection device of the series power module comprises a second direct current capacitor C2, the power loss protection switch comprises a normally closed node of a second relay K2 and a normally open node of a third relay K3 which are connected in series, the power loss detection circuit comprises a second auxiliary loop H2 and a third auxiliary loop H3, an output end of the second auxiliary loop H2 is connected in parallel to two ends of the second direct current capacitor C2, and an output end of the third auxiliary loop H3 is connected in parallel to two ends of the first direct current capacitor C1, the method comprises the following procedures, as shown in fig. 13.

In S310, the power supply unit 2 is turned on, the voltages of the first dc capacitor C1 and the second dc capacitor C2 gradually increase, the coil of the second relay K2 is energized, and the normally closed node of the second relay K2 is turned off.

The voltages of the first direct current capacitor C1 and the second direct current capacitor C2 continue to rise, and after the coil of the third relay K3 reaches the action voltage, the normally-open node of the third relay K3 is closed. When the circuit breaker normally operates, the coils of the second relay K2 and the third relay K3 are in an electrified state, and the power-off protection switch is in an off position.

In S320, when the power supply unit 2 loses power, the voltage of the second dc capacitor C2 rapidly drops, the coil of the second relay K2 loses power, and the normally closed node of the second relay K2 is closed.

In S330, the first dc capacitor C1 discharges, the coil of the third relay K3 turns on, the normally open node of the third relay K3 is closed, the closing coil L1 of the bypass switch turns on, and the bypass switch KM is closed.

According to the technical scheme provided by the embodiment of the application, the bypass switch can be reliably closed when the power supply unit is powered off, and the system reliability is greatly improved. The embodiment of the application also provides a method for realizing the power failure detection circuit, the automatic detection when the power supply unit is in power failure is realized through the reasonable configuration of the relay coil in the circuit, and the automatic switch-on of the bypass switch is realized after the coil is powered on.

The above embodiments are only for illustrating the technical idea of the present application, and the protection scope of the present application is not limited thereby, and any modifications made on the basis of the technical solution according to the technical idea presented in the present application fall within the protection scope of the present application.