Auxiliary power supply system
By designing an auxiliary power system combining DC and AC power supplies, and using double-knife and double-throw switches to achieve seamless switching, the problems of complex structure and high cost in the existing technology are solved, and the reliable power supply and cost reduction of the auxiliary power supply are achieved.
Patent Information
- Application Number
- CN202421910117.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-08-07
- Publication Date
- 2025-06-24
- Estimated Expiration
- 2034-08-07
AI Technical Summary
In the prior art, the auxiliary power system requires the deployment of two independent DC/DC and AC/DC power systems, resulting in complex structure and high cost.
Design an auxiliary power system to achieve seamless switching between DC and AC power through components such as DC power, AC power, diode and DC/DC converter, combined with dual-knife double-throw switch.
Seamless switching between the two input sources is achieved, ensuring reliable power supply of auxiliary power, and reducing the structural complexity and cost of the system.
Smart Images
Figure CN223024165U_ABST
Abstract
Description
Technical Field
[0001] The utility model belongs to the technical field of power supply, and particularly relates to an auxiliary power supply system. Background Art
[0002] In the energy storage cabinet systems on the market, an auxiliary power supply is generally configured inside a high-voltage box or inside a power conversion system (PCS) to supply power to a fire protection system, an energy management unit (EMU), or a PCS, etc. The auxiliary power supply generally has multiple input source requirements, such as a high-voltage DC source from an energy storage battery, an external UPS, or power taken from the source network side of the PCS.
[0003] The existing conventional method is to adopt two sets of auxiliary power supply systems at the same time. One set is a DC / DC auxiliary power supply, and the other set is an AC / DC auxiliary power supply. The secondary DC outputs of the two sets of power supplies are used in parallel or in series with diodes. However, adopting such a scheme requires deploying two independent power supply systems, and the system structure is complex and the cost is high. Summary of the Utility Model
[0004] The purpose of the utility model is to provide an auxiliary power supply system to solve the above problems existing in the prior art.
[0005] To achieve the above purpose, the utility model adopts the following technical solutions:
[0006] An auxiliary power supply system includes: a DC power supply, an AC power supply, a first diode, a second diode, a third diode, a fourth diode, a first capacitor, a second capacitor, a DC / DC converter, and a double-pole double-throw switch;
[0007] The double-pole double-throw switch includes a conductive knife switch blade, a first static contact group, and a second static contact group. The conductive knife switch blade includes a first knife switch blade and a second knife switch blade. The first static contact group includes a first static contact and a second static contact. The second static contact group includes a third static contact and a fourth static contact;
[0008] The anode of the first diode is connected to the positive pole of the DC power supply, the cathode of the first diode is connected to the first static contact, the cathode of the second diode is connected to the negative pole of the DC power supply, the anode of the second diode is connected to the second static contact, the anode of the third diode is connected to the AC power supply, the cathode of the third diode is connected to the third static contact, the cathode of the fourth diode is connected to the AC power supply, the anode of the fourth diode is connected to the fourth static contact, and when the first knife switch blade abuts against the first static contact, the second knife switch blade abuts against the second static contact, and when the first knife switch blade abuts against the third static contact, the second knife switch blade abuts against the fourth static contact;
[0009] The first knife switch blade is connected to the first input terminal of the DC / DC converter, the second knife switch blade is connected to the second input terminal of the DC / DC converter, and the first capacitor is connected between the first input terminal and the second input terminal of the DC / DC converter;
[0010] One end of the second capacitor is connected between the first output terminal of the DC / DC converter and the load, and the other end of the second capacitor is connected between the second output terminal of the DC / DC converter and the load.
[0011] Based on the above-disclosed content, the utility model provides a DC power supply, an AC power supply, a first diode, a second diode, a third diode, a fourth diode, a first capacitor, a second capacitor, a DC / DC converter, and a double-pole double-throw switch. The double-pole double-throw switch includes a conductive knife switch blade, a first static contact group, and a second static contact group. The conductive knife switch blade includes a first knife switch blade and a second knife switch blade. The first static contact group includes a first static contact and a second static contact. The second static contact group includes a third static contact and a fourth static contact. The anode of the first diode is connected to the positive pole of the DC power supply, and the cathode of the first diode is connected to the first static contact. The cathode of the second diode is connected to the negative pole of the DC power supply, and the anode of the second diode is connected to the second static contact. The anode of the third diode is connected to the AC power supply, and the cathode of the third diode is connected to the third static contact. The cathode of the fourth diode is connected to the AC power supply, and the anode of the fourth diode is connected to the fourth static contact. When the first knife switch blade abuts against the first static contact, the second knife switch blade abuts against the second static contact. When the first knife switch blade abuts against the third static contact, the second knife switch blade abuts against the fourth static contact. The first knife switch blade is connected to the first input terminal of the DC / DC converter, and the second knife switch blade is connected to the second input terminal of the DC / DC converter. One end of the first capacitor is connected between the first knife switch blade and the first input terminal of the DC / DC converter, and the other end of the first capacitor is connected between the second knife switch blade and the second input terminal of the DC / DC converter. One end of the second capacitor is connected between the first output terminal of the DC / DC converter and the load, and the other end of the second capacitor is connected between the second output terminal of the DC / DC converter and the load. In this way, two different input sources can be provided to supply power to the load, seamless switching can be achieved between the two input sources, reliable power supply of the auxiliary power supply can be ensured, and at the same time, two sets of independent power systems do not need to be deployed separately, the structural complexity of the auxiliary power supply system can be reduced, and the cost of auxiliary power supply can be reduced.
[0012] In a possible design, the auxiliary power supply system further includes a negative temperature coefficient thermistor, and the negative temperature coefficient thermistor is connected between the first knife switch blade and the first input terminal of the DC / DC converter.
[0013] In a possible design, the auxiliary power supply system further includes a first fuse and a second fuse. The first fuse is connected between the first diode and the DC power supply, and the second fuse is connected between the AC power supply and the third diode.
[0014] In a possible design, the auxiliary power supply system further includes an AC power failure detection circuit, and the AC power failure detection circuit is connected to the AC power supply.
[0015] In a possible design, the auxiliary power supply system further includes a double-pole double-throw relay. The double-pole double-throw relay includes a switch coil and the double-pole double-throw switch. The AC power failure detection circuit includes a fifth diode, a sixth diode, a seventh diode, an eighth diode, a first comparator, a first triode, a first P-channel field-effect transistor, and a second P-channel field-effect transistor. The cathodes of the fifth diode and the eighth diode are both connected to the AC power supply. The anode of the fifth diode is connected to the anode of the eighth diode. The gate of the first P-channel field-effect transistor is connected to the common connection end of the fifth diode and the eighth diode. The gate of the second P-channel field-effect transistor is connected between the anode of the fifth diode and the anode of the eighth diode. The drain of the first P-channel field-effect transistor is connected between the AC power supply and the cathode of the fifth diode. The source of the first P-channel field-effect transistor is connected to the anode of the sixth diode. The drain of the second P-channel field-effect transistor is connected between the AC power supply and the cathode of the eighth diode. The source of the second P-channel field-effect transistor is connected to the anode of the seventh diode. The cathodes of the sixth diode and the seventh diode are connected;
[0016] The first input terminal of the first comparator is connected to the common connection end of the sixth diode and the seventh diode. The second input terminal of the first comparator is connected to a reference voltage. The output terminal of the first comparator is connected to the base of the first triode. The emitter of the first triode is grounded. The collector of the first triode is connected to the switch coil.
[0017] In a possible design, the auxiliary power supply system further includes a DC power supply under-voltage protection circuit, and the DC power supply under-voltage protection circuit is connected to the DC power supply.
[0018] In a possible design, the DC power supply under-voltage protection circuit includes an amplifier, a second comparator, and a second triode. The two ends of the DC power supply are respectively and correspondingly connected to the two input terminals of the amplifier. The output terminal of the amplifier is connected to the first input terminal of the second comparator. The second input terminal of the second comparator is connected to a reference voltage. The output terminal of the second comparator is connected to the base of the second triode. The emitter of the second triode is grounded. The collector of the second triode is connected to the switch coil.
[0019] In a possible design, the auxiliary power supply system further includes a rectifier diode, and the rectifier diode is connected between the first output terminal of the DC / DC converter and the load.
[0020] Beneficial effects:
[0021] The auxiliary power supply system provided by the present utility model can supply power to a load with two different input sources, and seamless switching can be achieved between the two input sources to ensure reliable power supply of the auxiliary power supply. At the same time, it is not necessary to separately deploy two sets of independent power systems, which can reduce the structural complexity of the auxiliary power supply system, reduce the cost of auxiliary power supply, and facilitate practical application and promotion. BRIEF DESCRIPTION OF THE DRAWINGS
[0022] Figure 1 is a circuit schematic diagram of the auxiliary power supply system provided by an embodiment of the present application;
[0023] Figure 2 is a circuit schematic diagram of the AC power failure detection circuit provided by an embodiment of the present application;
[0024] Figure 3 is a circuit schematic diagram of the DC power shortage protection circuit provided by an embodiment of the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS
[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present utility model or the prior art, the following will briefly introduce the present utility model in combination with the drawings and the description of the embodiments or the prior art. Obviously, the following description of the structures of the drawings is only some embodiments of the present utility model. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings. It should be noted here that the description of these embodiments is used to help understand the present utility model, but does not constitute a limitation to the present utility model.
[0026] It should be understood that although terms such as first and second may be used herein to describe various units, these units should not be limited by these terms. These terms are only used to distinguish one unit from another. For example, the first unit may be called the second unit, and similarly, the second unit may be called the first unit, without departing from the scope of the exemplary embodiments of the present utility model.
[0027] It should be understood that for the term "and / or" that may appear in this article, it is only a description of the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B may represent: A exists alone, B exists alone, and A and B exist simultaneously; for the term " / and" that may appear in this article, it is a description of another association object relationship, indicating that two relationships may exist. For example, A / and B may represent: A exists alone, and A and B exist alone; in addition, for the character " / " that may appear in this article, generally, the front and rear associated objects are in an "or" relationship.
[0028] Such as Figure 1As shown in the figure, this embodiment provides an auxiliary power supply system, which includes a DC power supply DC, an AC power supply AC, a first diode D1, a second diode D2, a third diode D3, a fourth diode D4, a first capacitor C1, a second capacitor C2, a DC / DC converter, and a double-pole double-throw switch.
[0029] Among them, the double-pole double-throw switch includes a conductive knife switch blade, a first static contact group, and a second static contact group. The conductive knife switch blade includes a first knife switch blade Z1 and a second knife switch blade Z2. The first static contact group includes a first static contact K1 and a second static contact K2. The second static contact group includes a third static contact K3 and a fourth static contact K4.
[0030] The anode of the first diode D1 is connected to the positive electrode of the DC power supply DC, and the cathode of the first diode D1 is connected to the first static contact K1. The cathode of the second diode D2 is connected to the negative electrode of the DC power supply DC, and the anode of the second diode D2 is connected to the second static contact K2. The anode of the third diode D3 is connected to the AC power supply AC, and the cathode of the third diode D3 is connected to the third static contact K3. The cathode of the fourth diode D4 is connected to the AC power supply AC, and the anode of the fourth diode D4 is connected to the fourth static contact K4. The first knife switch blade Z1 and the second knife switch blade Z2 are connected by insulating plastic to ensure electrical isolation between them while maintaining a mechanical connection, that is, when the first knife switch blade Z1 abuts against the first static contact K1, the second knife switch blade Z2 abuts against the second static contact K2, and when the first knife switch blade Z1 abuts against the third static contact K3, the second knife switch blade Z2 abuts against the fourth static contact K4.
[0031] The first knife switch blade Z1 is connected to the first input terminal of the DC / DC converter, and the second knife switch blade Z2 is connected to the second input terminal of the DC / DC converter. The first capacitor C1 is connected between the first input terminal and the second input terminal of the DC / DC converter. One end of the second capacitor C2 is connected between the first output terminal of the DC / DC converter and the load, and the other end of the second capacitor C2 is connected between the second output terminal of the DC / DC converter and the load.
[0032] By setting the double-pole double-throw switch, the input source can be switched between DC and AC. In the embodiment of this application, the DC power supply DC may run out of power due to long-term standby. To ensure reliable power supply of the auxiliary power supply system, generally, the AC power supply AC is preferred for power supply.
[0033] Specifically, when powered by an AC power supply AC, the conductive knife switch blade can be switched to make the first knife blade Z1 abut against the third static contact K3, and the second knife blade Z2 abut against the fourth static contact K4. At this time, the loop where the AC power supply AC is located is turned on, and the alternating current output by the AC power supply AC is rectified into pulsating direct current through the third diode D3, the first capacitor C1 and the fourth diode D4. The direct current is chopped at high frequency by the DC / DC converter and filtered by the second capacitor C2 to output low-voltage direct current to supply power to the load.
[0034] When it is necessary to be powered by a DC power supply DC, the conductive knife switch blade can be switched to make the first knife blade Z1 abut against the first static contact K1, and the second knife blade Z2 abut against the second static contact K2. At this time, the loop where the DC power supply DC is located is turned on, and the high-voltage direct current output by the DC power supply DC is sent into the DC / DC converter through the first diode D1, the first capacitor C1 and the second diode D2. The DC / DC converter chops at high frequency and is filtered by the second capacitor C2 to output low-voltage direct current to supply power to the load.
[0035] In one or more embodiments, the auxiliary power supply system provided by the embodiments of the present application further includes a negative temperature coefficient thermistor R1, and the negative temperature coefficient thermistor R1 is connected between the first knife blade Z1 and the first input end of the DC / DC converter. By setting the negative temperature coefficient thermistor, the impact current can be effectively suppressed, the components in the circuit can be prevented from being damaged by excessive current, the service life of the components in the circuit can be prolonged, and the safety of the circuit can be improved.
[0036] In one or more embodiments, the auxiliary power supply system provided by the embodiments of the present application further includes a first fuse FUSE1 and a second fuse FUSE2. The first fuse FUSE1 is connected between the first diode D1 and the DC power supply DC, and the second fuse FUSE2 is connected between the AC power supply AC and the third diode D3. By setting the first fuse FUSE1 and the second fuse FUSE2, it is possible to avoid damage to the equipment caused by abnormal increase in current due to faults such as overload and short circuit, and realize overcurrent and overload protection.
[0037] Please refer to Figure 1 , a rectifying diode D9 can also be provided between the first output end of the DC / DC converter and the load in the auxiliary power supply system provided by the embodiments of the present application. When the auxiliary power supply system supplies power to the load, the direct current output by the DC / DC converter can be rectified through the rectifying diode D9.
[0038] Please refer to Figure 2, when powering a load through an auxiliary power supply system, it is preferentially powered by the AC power supply AC. Once the AC power supply AC is disconnected or the voltage is too low, the power supply requirement of the load cannot be met. Based on this, the auxiliary power supply system provided by the embodiments of the present application is also provided with an AC power failure detection circuit. The AC power failure detection circuit is connected to the AC power supply AC and is used to switch a double-pole double-throw switch to adjust to be powered by the DC power supply DC when it detects that the input of the AC power supply AC is disconnected or the voltage is too low.
[0039] Specifically, the auxiliary power supply system further includes a double-pole double-throw relay. The double-pole double-throw relay includes the aforementioned double-pole double-throw switch. The AC power failure detection circuit includes a fifth diode D5, a sixth diode D6, a seventh diode D7, an eighth diode D8, a first comparator EA1, a first triode Q1, a first P-channel MOS field effect transistor MOS1, and a second P-channel MOS field effect transistor MOS2. The cathodes of the fifth diode D5 and the eighth diode D8 are both connected to the AC power supply AC. The anode of the fifth diode D5 is connected to the anode of the eighth diode D8. The gate of the first P-channel MOS field effect transistor MOS1 is connected to the common connection end of the fifth diode D5 and the eighth diode D8. The gate of the second P-channel MOS field effect transistor MOS2 is connected between the anode of the fifth diode D5 and the anode of the eighth diode D8. The drain of the first P-channel MOS field effect transistor MOS1 is connected between the AC power supply AC and the cathode of the fifth diode D5. The source of the first P-channel MOS field effect transistor MOS1 is connected to the anode of the sixth diode D6. The drain of the second P-channel MOS field effect transistor MOS2 is connected between the AC power supply AC and the cathode of the eighth diode D8. The source of the second P-channel MOS field effect transistor MOS2 is connected to the anode of the seventh diode D7. The cathodes of the sixth diode D6 and the seventh diode D7 are connected.
[0040] The first input terminal of the first comparator EA1 is connected to the common connection end of the sixth diode D6 and the seventh diode D7. The second input terminal of the first comparator EA1 is connected to a reference voltage. The output terminal of the first comparator EA1 is connected to the base of the first triode Q1. The emitter of the first triode Q1 is grounded. The collector of the first triode Q1 is connected to the switch coil.
[0041] By setting the AC power failure detection circuit, the output voltage of the AC power supply AC can be detected. When the output voltage of the AC power supply AC is too low or zero (i.e., disconnected) and less than the reference voltage, a level signal can be output by the first comparator EA1 and control the conduction / cutoff of the collector and emitter of the first triode Q1, so that the current of the switch coil of the double-pole double-throw relay changes, thereby controlling the double-pole double-throw switch of the double-pole double-throw relay to switch, and switching from being powered by the AC power supply AC to being powered by the DC power supply DC.
[0042] In the embodiment of the present application, the drain of the first P-channel MOSFET MOS1 is connected between the AC power supply AC and the cathode of the fifth diode D5, the source of the first P-channel MOSFET MOS1 is connected to the anode of the sixth diode D6, the drain of the second P-channel MOSFET MOS2 is connected between the AC power supply AC and the cathode of the eighth diode D8, and the source of the second P-channel MOSFET MOS2 is connected to the anode of the seventh diode D7. It can be understood that in some other embodiments, it may also be that the source of the first P-channel MOSFET MOS1 is connected between the AC power supply AC and the cathode of the fifth diode D5, the drain of the first P-channel MOSFET MOS1 is connected to the anode of the sixth diode D6, the source of the second P-channel MOSFET MOS2 is connected between the AC power supply AC and the cathode of the eighth diode D8, and the drain of the second P-channel MOSFET MOS2 is connected to the anode of the seventh diode D7.
[0043] Please refer to Figure 3 , the auxiliary power supply system provided by the embodiment of the present application further includes a DC power supply under-voltage protection circuit, and the DC power supply under-voltage protection circuit is connected to the DC power supply DC. Specifically, the DC power supply under-voltage protection circuit includes an amplifier AMP, a second comparator EA2, and a second triode Q2. The two ends of the DC power supply DC are respectively and correspondingly connected to the two input ends of the amplifier AMP, the output end of the amplifier AMP is connected to the first input end of the second comparator EA2, the second input end of the second comparator EA2 is connected to a reference voltage, the output end of the second comparator EA2 is connected to the base of the second triode Q2, the emitter of the second triode Q2 is grounded, and the collector of the second triode Q2 is connected to the switching coil.
[0044] By setting the DC power supply under-voltage protection circuit, when powered by the DC power supply DC, if the voltage output by the DC power supply DC is too low and less than the reference voltage, a level signal can be output by the second comparator EA2 to control the conduction / cutoff of the collector and emitter of the second triode Q2, so that the current of the switching coil of the double-pole double-throw relay changes, thereby controlling the switching of the double-pole double-throw switch of the double-pole double-throw relay to switch from being powered by the DC power supply DC to being powered by the AC power supply AC.
[0045] In summary, the auxiliary power supply system provided by the present utility model can provide two different input sources to supply power to the load, and seamless switching can be achieved between the two input sources to ensure reliable power supply of the auxiliary power supply. At the same time, it is not necessary to deploy two sets of independent power systems separately, which can reduce the structural complexity of the auxiliary power supply system, reduce the auxiliary power supply cost, and facilitate practical application and popularization.
[0046] Finally, it should be noted that the above are only the preferred embodiments of the present utility model and are not intended to limit the protection scope of the present utility model. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present utility model shall be included within the protection scope of the present utility model.
Claims
1. An auxiliary power supply system, characterized in that: include: A direct current power supply (DC), an alternating current power supply (AC), a first diode (D1), a second diode (D2), a third diode (D3), a fourth diode (D4), a first capacitor (C1), a second capacitor (C2), a DC / DC converter, and a double-pole double-throw switch; The double-pole double-throw switch comprises a conductive knife switch, a first static contact group and a second static contact group, wherein the conductive knife switch comprises a first knife switch (Z1) and a second knife switch (Z2), the first static contact group comprises a first static contact (K1) and a second static contact (K2), and the second static contact group comprises a third static contact (K3) and a fourth static contact (K4); The anode of the first diode (D1) is connected to the positive electrode of the DC power supply (DC), the cathode of the first diode (D1) is connected to the first static contact (K1), the cathode of the second diode (D2) is connected to the negative electrode of the DC power supply (DC), the anode of the second diode (D2) is connected to the second static contact (K2), the anode of the third diode (D3) is connected to the AC power supply (AC), the cathode of the third diode (D3) is connected to the third static contact (K3), the cathode of the fourth diode (D4) is connected to the AC power supply (AC), the anode of the fourth diode (D4) is connected to the fourth static contact (K4), and when the first knife gate piece (Z1) is in contact with the first static contact (K1), the second knife gate piece (Z2) is in contact with the second static contact (K2), and when the first knife gate piece (Z1) is in contact with the third static contact (K3), the second knife gate piece (Z2) is in contact with the fourth static contact (K4); The first switch blade (Z1) is connected to a first input end of the DC / DC converter, the second switch blade (Z2) is connected to a second input end of the DC / DC converter, and the first capacitor (C1) is connected between the first input end and the second input end of the DC / DC converter; One end of the second capacitor (C2) is connected between the first output end of the DC / DC converter and the load, and the other end of the second capacitor (C2) is connected between the second output end of the DC / DC converter and the load.
2. The auxiliary power supply system according to claim 1, characterized in that: It also comprises a negative temperature coefficient thermistor (R1), wherein the negative temperature coefficient thermistor (R1) is connected between the first knife switch (Z1) and the first input end of the DC / DC converter.
3. The auxiliary power supply system according to claim 1, characterized in that: It also includes a first fuse (FUSE1) and a second fuse (FUSE2), wherein the first fuse (FUSE1) is connected between the first diode (D1) and the DC power supply (DC), and the second fuse (FUSE2) is connected between the AC power supply (AC) and the third diode (D3).
4. The auxiliary power supply system according to claim 1, characterized in that: It also includes an AC power failure detection circuit, which is connected to the AC power supply (AC).
5. The auxiliary power supply system according to claim 4, characterized in that: The invention also comprises a double-pole double-throw relay, wherein the double-pole double-throw relay comprises a switch coil and the double-pole double-throw switch, and the AC power-off detection circuit comprises a fifth diode (D5), a sixth diode (D6), a seventh diode (D7), an eighth diode (D8), a first comparator (EA1), a first triode (Q1), a first P-channel field effect transistor (MOS1) and a second P-channel field effect transistor (MOS2), wherein the cathode of the fifth diode (D5) and the cathode of the eighth diode (D8) are both connected to the AC power supply (AC), the anode of the fifth diode (D5) is connected to the anode of the eighth diode (D8), and the gate of the first P-channel field effect transistor (MOS1) is connected to the common connection of the fifth diode (D5) and the eighth diode (D8). end, the gate of the second P-channel field effect transistor (MOS2) is connected between the anode of the fifth diode (D5) and the anode of the eighth diode (D8), the drain of the first P-channel field effect transistor (MOS1) is connected between the alternating current power supply (AC) and the cathode of the fifth diode (D5), the source of the first P-channel field effect transistor (MOS1) is connected to the anode of the sixth diode (D6), the drain of the second P-channel field effect transistor (MOS2) is connected between the alternating current power supply (AC) and the cathode of the eighth diode (D8), the source of the second P-channel field effect transistor (MOS2) is connected to the anode of the seventh diode (D7), and the cathode of the sixth diode (D6) is connected to the cathode of the seventh diode (D7); The first input end of the first comparator (EA1) is connected to the common connection end of the sixth diode (D6) and the seventh diode (D7), the second input end of the first comparator (EA1) is connected to a reference voltage, the output end of the first comparator (EA1) is connected to the base of the first transistor (Q1), the emitter of the first transistor (Q1) is grounded, and the collector of the first transistor (Q1) is connected to the switch coil.
6. The auxiliary power supply system according to claim 5, characterized in that: It also includes a DC power supply under-power protection circuit, and the DC power supply under-power protection circuit is connected to the DC power supply (DC).
7. The auxiliary power supply system according to claim 6, characterized in that: The DC power supply underpower protection circuit comprises an amplifier (AMP), a second comparator (EA2) and a second triode (Q2); two ends of the DC power supply (DC) are respectively connected to two input ends of the amplifier (AMP) in a one-to-one correspondence; the output end of the amplifier (AMP) is connected to the first input end of the second comparator (EA2); the second input end of the second comparator (EA2) is connected to a reference voltage; the output end of the second comparator (EA2) is connected to the base of the second triode (Q2); the emitter of the second triode (Q2) is grounded; and the collector of the second triode (Q2) is connected to the switch coil.
8. The auxiliary power supply system according to claim 1, characterized in that: It also includes a rectifier diode (D9), which is connected between the first output terminal of the DC / DC converter and the load.