CN206727724U - Active and standby dc source with defencive function - Google Patents

Abstract

The utility model discloses a main and standby DC power supply with protection function, which comprises a switching circuit and a power supply protection circuit connected with the main DC source and the standby DC source; The transistor Q4 is connected to the anode of the diode D2, the source of the transistor Q4 is grounded, and the gate is connected to the drive resistor R5 in series; the resistor R2 is connected to the cathode of the diode D1, the gate is connected to the transistor Q2 of the resistor R2, and the drain of the transistor Q2 is connected to the main The negative output terminal and the source of the DC source and the backup DC source are grounded; the emitter is connected to the triode Q3 of the gate of the transistor Q2, the collector of the triode Q3 is grounded, and the base is connected in series with the driving resistor R6, and the driving resistor R6 and the driving resistor R5 The common end of the circuit is connected to the short-circuit detection circuit. The utility model can effectively protect the power supply when a short circuit is detected, and has the advantages of simple structure, low realization cost and stable and reliable operation.

Description

Main and backup DC power supply with protection function

technical field

The utility model relates to a power supply, in particular to a primary and backup DC power supply with a protection function.

Background technique

DC power supply is widely used in various electronic devices, and the DC power supply of lithium battery is the most widely used. The existing DC power supply has the following defects:

1. Generally, there is no main and backup power supply, which cannot meet the actual use needs of electronic equipment with high requirements for work stability.

2. In order to prevent short circuit, a large current fuse is connected in series at the output end of the DC power supply. When a short circuit occurs, the fuse melts and disconnects, but this short circuit protection circuit requires frequent replacement of the fuse, resulting in high circuit maintenance costs and troublesome operation.

Utility model content

In order to overcome the defects of the prior art, the utility model proposes a primary and backup DC power supply with simple circuit structure, high reliability and protection function.

The utility model discloses a main-standby DC power supply with a protection function, which comprises: a main-standby DC power supply with a protection function, including a parallel main DC source and a backup DC source, and a main DC source connected with the backup DC source Switching circuit and power supply protection circuit; the power supply protection circuit includes: an inductor L1 and a diode D2 connected in series at the positive output end of the switching circuit; a transistor Q4 whose drain is connected to the anode of the diode D2, the source of the transistor Q4 is grounded, and the gate is connected in series to drive Resistor R5; resistor R2 connected to the cathode of diode D1, transistor Q2 connected to the gate of resistor R2, the drain of the transistor Q2 is connected to the negative output terminal of the main DC source and the negative output terminal of the backup DC source, and the source is grounded; the emitter The triode Q3 connected to the gate of the transistor Q2, the collector of the triode Q3 is grounded, the base of the triode Q3 is connected in series with the drive resistor R6, and the drive resistor R6 is connected in series with the drive resistor R5, and the common end of the drive resistor R6 and the drive resistor R5 is connected for short circuit detection circuit.

Wherein, the power supply protection circuit further includes a diode D4 connected between the positive output terminal of the switching circuit and the ground, and the anode of the diode D4 is grounded.

Wherein, the short-circuit detection circuit includes: a sampling resistor R3 connected in series between the negative output terminal V- of the main and standby DC power supply and the ground, the anode of the diode D3 connected to the sampling resistor R3, and the cathode of the diode D3 connected to the comparator U2 The input end of the comparator U2 is connected to the common end of the drive resistor R6 and the drive resistor R5.

Wherein, the switching circuit includes: a transistor Q1 whose gate is connected to the positive output terminal of the main DC source, the drain of the transistor Q1 is connected to the positive output terminal of the backup DC source, the gate of the transistor Q1 is connected to the source in series with a diode D1, and the diode The anode of D1 is grounded through the resistor R1, and the cathode of the diode D1 is connected to the positive output terminal of the switching circuit.

Compared with the prior art, the utility model has the following beneficial effects:

The main and backup DC power supply proposed by the utility model, the main and backup DC sources can realize seamless switching output, and improve the reliability of the power supply; the main and backup DC power supply also has a power supply protection circuit, which can effectively protect the The power supply has the advantages of simple structure, low implementation cost and stable and reliable operation, and can be widely applied to power supply circuits of various topological structures.

Description of drawings

Fig. 1 is a schematic diagram of a modular structure of the main and backup DC power supplies.

Fig. 2 is a schematic circuit diagram of an embodiment of the present invention.

detailed description

As shown in FIG. 1 , the main and backup DC power supply proposed by the utility model includes a parallel main DC source 1 and a backup DC source 2 , a switching circuit 3 connected to the main DC source 1 and the backup DC source 2 , and a power supply protection circuit 4 . The switching circuit 3 selectively uses the main DC source 1 or the backup DC source 2 as a power supply, and realizes seamless switching between the main DC source 1 and the backup DC source 2 . The power supply protection circuit 4 provides power output and short circuit protection.

Combined with Figure 2. The switching circuit is used to realize switching output between the main DC source 1 and the backup DC source 2, the switching circuit includes: a transistor Q1 whose gate is connected to the positive output terminal of the main DC source 1, and the drain of the transistor Q1 is connected to the backup DC source 2 At the positive output terminal, the gate of the transistor Q1 is connected to the source in series with a diode D1, and the anode of the diode D1 is grounded through a resistor R1. When the main DC source 1 supplies power, the diode D1 is turned on and the transistor Q1 is turned off, and the positive output terminal of the main DC source 1 outputs current; on the contrary, when the power of the main DC source 1 is insufficient or disconnected, the diode D1 is turned off and the transistor Q1 is turned on. The positive output terminal of the DC source 2 outputs current through the transistor Q1. It can be seen that seamless switching between the main direct current source 1 and the backup direct current source 2 is possible through the switching circuit.

The power supply protection circuit 4 includes: an inductor L1 and a diode D2 connected in series to the cathode of the diode D1, the cathode of the diode D2 is the positive output terminal V+ of the backup DC power supply; a transistor Q4 whose drain is connected to the anode of the diode D2, and the source of the transistor Q4 The electrode is grounded, and the gate is connected in series with the drive resistor R5; the diode D4 is connected between the cathode of the diode D1 and the ground, and the anode of the diode D4 is grounded; the resistor R2 connected to the cathode of the diode D1, the gate is connected to the transistor Q2 of the resistor R2, and the transistor Q2 The drains of the transistors are connected to the negative output terminal of the main DC source 1 and the negative output terminal of the standby DC source 2, and the source is grounded; the emitter is connected to the triode Q3 of the gate of the transistor Q2, the collector of the triode Q3 is grounded, and the base is connected in series The driving resistor R6 is connected in series with the driving resistor R5, and the common end of the driving resistor R6 and the driving resistor R5 is connected to a short-circuit detection circuit.

The short-circuit detection circuit includes: a sampling resistor R3 connected in series between the negative output terminal V- of the main and standby DC power supply and the ground, the anode of which is connected to the diode D3 of the sampling resistor R3, and the cathode of the diode D3 is connected to the input terminal of the comparator U2 , and the output end of the comparator U2 is connected to the common end of the driving resistor R6 and the driving resistor R5.

During normal operation, the gate of transistor Q2 is at high level, so it is turned on, so that the current output by diode D1 is output through inductor L1 and diode D2. At this time, the output terminal of comparator U2 is at low level, so both transistor Q3 and transistor Q4 are cut off. When a short circuit occurs between the positive output terminal V+ and the negative output terminal V- of the main and standby DC power supplies, the voltage across the sampling resistor R3 rises instantaneously, and the output terminal of the comparator U2 changes from low level to high level, thus the triode Both Q3 and transistor Q4 are turned on, pull down the gate of transistor Q2 to make its potential become zero potential, turn off transistor Q2 instantly so that no closed loop is formed between the positive and negative output terminals of the main DC source 1 or backup DC source 2 , so as to play a protective function; and, the energy in the inductor L1 forms a discharge circuit through the transistor Q4 and the diode D4, which avoids damage to the power supply circuit caused by an arc caused by the instantaneous short circuit protection of the inductor L1 without a discharge circuit.

The above descriptions are only preferred embodiments of the present utility model, and are not intended to limit the present utility model. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present utility model shall be included in this utility model. within the scope of protection of utility models.

Claims (4)

1. A kind of 1. active and standby dc source with defencive function, it is characterised in that main DC source and standby DC source including parallel connection, The switching circuit and power supply protection circuit being connected with main DC source and standby DC source；The power supply protection circuit includes：It is serially connected in The inductance L1 and diode D2 of switching circuit positive output end；The transistor Q4, transistor Q4 of drain electrode connection diode D2 anodes Source ground, grid concatenation driving resistance R5；Connect the resistance R2 of diode D1 negative electrodes, grid connection resistance R2 transistor Q2, the transistor Q2 drain electrode are all connected with the negative output terminal of main DC source and negative output terminal, the source ground of standby DC source；Hair Emitter-base bandgap grading connects the triode Q3 of transistor Q2 grids, triode Q3 grounded collector, base stage concatenation driving resistance R6, and drives Dynamic resistance R6 concatenates with driving resistance R5, and drives resistance R6 with driving resistance R5 common port to be connected short-circuit detecting circuit.
2. 2. the active and standby dc source with defencive function according to claim 1, it is characterised in that the power supply protection circuit also wraps Include the diode D4 between connection switching circuit positive output end and ground, diode D4 plus earth.
3. 3. the active and standby dc source with defencive function according to claim 1, it is characterised in that the short-circuit detecting circuit bag Include：The sample resistance R3 being serially connected between the negative output terminal V- of the active and standby dc source and ground, anode connection sampling resistor R3's Diode D3, the diode D3 negative electrode connection comparator U2 input, and comparator U2 output end connection driving resistance R6 and driving resistance R5 common port.
4. 4. according to the active and standby dc source with defencive function of claim 1 or 2 or 3, it is characterised in that the switching circuit bag Include：Grid connects the transistor Q1 of main DC source positive output end, and transistor Q1 drain electrode connects the positive output of standby DC source End, transistor Q1 grid series diode D1 connection source electrodes, diode D1 anode are grounded by resistance R1, two pole Pipe D1 negative electrode connection switching circuit positive output end.