CN109600045B

CN109600045B - DC-DC converter

Info

Publication number: CN109600045B
Application number: CN201811251794.3A
Authority: CN
Inventors: 严为人
Original assignee: Zhangjiagang Huawei Electronics Co Ltd
Current assignee: Zhangjiagang Huawei Electronics Co Ltd
Priority date: 2018-10-25
Filing date: 2018-10-25
Publication date: 2021-09-03
Anticipated expiration: 2038-10-25
Also published as: CN109600045A

Abstract

The invention relates to a converter, in particular to a DC-DC converter, which comprises a conversion circuit, a first standby power supply, a first voltage detection module and a first execution module, wherein the conversion circuit comprises an input module and an output module which are mutually coupled through a transformer; when the front end of the conversion circuit is disconnected to reduce the voltage, the first execution module controls the first standby power supply to be connected into the conversion circuit according to the output of the first voltage detection module, so that electric energy is provided for the conversion circuit, and the working reliability of the device is improved.

Description

DC-DC converter

Technical Field

The present invention relates to a converter, and more particularly, to a DC-DC converter.

Background

The advent of synchronous rectification technology has improved the efficiency of DC-DC converters, and chinese invention with publication number CN101860219A discloses a DC-DC converter, comprising an input part and an output part coupled through a transformer; the input part comprises a magnetic reset circuit coupled with the primary side of the transformer in parallel, and a third MOS tube of which the drain electrode is coupled with the primary side of the transformer in series, and the source electrode of the third MOS tube is coupled to the ground; the output part comprises a first MOS tube, a second MOS tube, a fourth MOS tube, a diode, a first auxiliary winding, a second auxiliary winding, a filter inductor and a filter capacitor.

The technical scheme of the invention has the advantages that the first auxiliary winding and the second auxiliary winding can be time-division multiplexed, the number of turns of the windings can be compressed, and the volume is reduced; in addition, the first MOS tube is lower than the grid voltage of the second MOS tube, so that the reliability of the MOS tube is further improved.

However, in the operation process of the converter, the front end of the converter is disconnected and cannot normally operate.

Disclosure of Invention

The purpose of the present invention is to provide a highly reliable DC-DC converter.

The above object of the present invention is achieved by the following technical solutions:

a DC-DC converter comprises a conversion circuit, a first standby power supply, a first voltage detection module and a first execution module, wherein the conversion circuit comprises an input module and an output module which are mutually coupled through a transformer, the first standby power supply, the first voltage detection module is used for detecting the voltage of the front end of the conversion circuit, and the first execution module is used for controlling the connection and disconnection between the first standby power supply and the conversion circuit according to the output of the voltage detection module.

By adopting the technical scheme, when the front end of the conversion circuit is disconnected and the voltage is reduced, the first execution module controls the first standby power supply to be connected into the conversion circuit according to the output of the first voltage detection module, so that electric energy is provided for the conversion circuit, and the working reliability of the device is improved.

The invention is further configured to: the power supply control circuit also comprises a second standby power supply, a second voltage detection module used for detecting the voltage of the output end of the first standby power supply and a second execution module used for controlling the on-off between the second standby power supply and the conversion circuit according to the output of the second voltage detection module.

By adopting the technical scheme, when the electric energy of the first standby power supply is low, the second standby power supply is connected into the conversion circuit, and the working reliability of the device is further improved.

The invention is further configured to: the first voltage detection module comprises a first voltage detection circuit and a first comparator, the first voltage detection circuit is used for detecting the voltage of the front end of the conversion circuit, the first comparator responds to the fact that the output value of the first voltage detection circuit is smaller than a first preset value and sends a first execution signal to the first execution module, and the first execution module acts in response to the first execution signal.

By adopting the technical scheme, when the front end of the conversion circuit is disconnected and the voltage is reduced, the output value of the voltage detection circuit is smaller than the first preset value, the first comparator outputs the first execution signal, and the first execution module controls the first standby power supply to be connected into the conversion circuit and provide electric energy for the conversion circuit.

The invention is further configured to: the first execution module comprises a first switch piece and a first relay, the first switch piece is connected to a power-on loop of the first relay and is turned on in response to a first execution signal, and a normally open contact of the first relay is connected between the first standby power supply and the input end of the conversion circuit.

By adopting the technical scheme, after the first execution signal is received, the first switch piece is conducted, the first relay acts, and the loop between the first standby power supply and the conversion circuit is switched on.

The invention is further configured to: the second voltage detection module comprises a second voltage detection circuit for detecting the voltage of the output end of the first standby power supply, a first AND gate circuit and a second comparator, the second comparator compares the output value of the second voltage detection circuit with a second preset value, the first AND gate circuit sends out a second execution signal in response to the fact that the output value of the second voltage detection circuit is smaller than the second preset value and the first execution signal, and the second execution module acts in response to the second execution signal.

By adopting the technical scheme, when the electric quantity of the first standby power supply is lower, the output value of the second voltage detection circuit is smaller than the second preset value, the second execution module acts to connect the second standby power supply to the conversion circuit, and the working reliability of the device is further improved.

The invention is further configured to: the second execution module comprises a second switch piece and a second relay, the second switch piece is connected to a power-on loop of the second relay and is turned on in response to a second execution signal, a normally open contact of the second relay is connected between the second standby power supply and the input end of the conversion circuit, and a normally closed contact of the second relay is connected between the first relay and the first switch piece.

By adopting the technical scheme, after the second execution signal is received, the second switch part is switched on, the power-on loop of the second relay is switched on, the second relay acts to switch on the loop between the second standby power supply and the conversion circuit, and meanwhile, the first relay resets to switch off the loop between the first standby power supply and the conversion circuit.

The invention is further configured to: one normally closed contact of the first relay is connected to a charging circuit of the first standby power supply, and one normally closed contact of the second relay is connected to a charging circuit of the second standby power supply.

By adopting the technical scheme, when the first standby power supply or the second standby power supply is connected into the conversion circuit, the corresponding charging loop is disconnected, and the situation that the first standby power supply or the second standby power supply generates too much heat is reduced.

The invention is further configured to: the first relay is connected with the first voltage detection circuit, the second relay is connected with the second voltage detection circuit, the third voltage detection circuit is used for detecting the voltage of the output end of the second standby power supply, the third comparator is used for comparing the output value of the third voltage detection circuit with a third preset value, the second AND circuit responds to the fact that the output value of the third voltage detection circuit is smaller than the third preset value, the second AND circuit outputs a third execution signal, and the third execution module responds to the third execution signal to act.

By adopting the technical scheme, when the electric quantity of the second standby power supply is lower, the output value of the third voltage detection circuit is smaller than the third preset value, the second AND gate circuit outputs the third execution signal, the third execution module is connected with the power-on loop of the first relay, the first relay acts, the first standby power supply supplies power for the conversion circuit, the second relay resets at the moment, and then the third relay resets.

The invention is further configured to: the third execution module comprises a third switch piece and a third relay, the third switch piece is connected to an electrifying loop of the third relay and is conducted corresponding to a third execution signal, and a normally open contact of the third relay is bridged with the first switch piece and a normally closed contact of the second relay connected to the first switch piece.

By adopting the technical scheme, when the third execution signal is received, the third switch piece is conducted to communicate the electrifying loop of the third relay, and the third relay acts to connect the electrifying loop of the first relay.

In conclusion, the beneficial technical effects of the invention are as follows:

1. when the front end of the conversion circuit is broken, the first standby power supply is connected into the conversion circuit to provide electric energy for the conversion circuit, so that the working reliability of the device is improved;

2. when the electric quantity of the first standby power supply is low, the second standby power supply is connected into the conversion circuit, and the first standby power supply is charged;

3. when the electric quantity of the second standby power supply is lower, the first standby power supply is connected into the conversion circuit, and meanwhile, the second standby power supply is charged.

Drawings

FIG. 1 is a schematic diagram of the present embodiment;

fig. 2 is a schematic diagram of the conversion circuit in the present embodiment.

Reference numerals: 1. a conversion circuit; 2. a transformer; 3. an input module; 4. an output module; 5. a first backup power supply; 6. a second backup power supply; 7. a first voltage detection circuit; 8. a first comparator; 9. a first switching member; 10. a first relay; 11. a second voltage detection circuit; 12. a first AND gate circuit; 13. a second comparator; 14. a second switching member; 15. a second relay; 16. a third voltage detection circuit; 17. a second AND circuit; 18. a third comparator; 19. a third switching member; 20. a third relay; 21. a magnetic reset circuit; 22. a first MOS transistor; 23. a second MOS transistor; 24. a third MOS transistor; 25. a fourth MOS transistor; 26. a first auxiliary winding; 27. a second auxiliary winding.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings.

Referring to fig. 1 and 2, a DC-DC converter disclosed in the present invention includes a converter circuit 1, where the converter circuit 1 includes an input module 3 and an output module 4 coupled to each other through a transformer 2, and further includes a first standby power supply 5, a second standby power supply 6, a first voltage detection module for detecting a voltage at a front end of the converter circuit 1, and a first execution module for controlling on/off between the first standby power supply 5 and the converter circuit 1 according to an output of the voltage detection module.

The first voltage detection module comprises a first voltage detection circuit 7 and a first comparator 8, wherein the first voltage detection circuit 7 is used for detecting the voltage of the front end of the conversion circuit 1, the first execution module comprises a first switch 9 and a first relay 10, the output end of the first voltage detection circuit 7 is electrically connected to the inverting input end of the first comparator 8, the non-inverting input end of the first comparator 8 receives a first preset signal used for providing a first preset value, and when the output value of the first voltage detection circuit 7 is smaller than the first preset value, the first comparator 8 outputs a first execution signal with a high level.

The first switch 9 is an NMOS transistor, a gate thereof is electrically connected to the output terminal of the first comparator 8, a source thereof is grounded, a coil K1 of the first relay 10 is connected between a power supply VCC and a drain of the first switch 9, a normally open contact K1-1 of the first relay 10 is connected between the output terminal of the first backup power supply 5 and the output terminal of the inverter circuit 1, a normally closed contact K1-2 thereof is connected to a charging loop of the first backup power supply 5, when the first comparator 8 outputs a first execution signal of a high level, the first switch 9 is turned on, the coil K1 of the first relay 10 is powered on, and the first relay 10 operates.

The power supply control circuit also comprises a second voltage detection module for detecting the voltage of the output end of the first standby power supply 5 and a second execution module for controlling the on-off between the second standby power supply 6 and the conversion circuit 1 according to the output of the second voltage detection module.

The second voltage detection module comprises a second voltage detection circuit 11 for detecting the voltage of the output end of the first standby power supply 5, a first and gate circuit 12 and a second comparator 13, the second execution module comprises a second switch 14 and a second relay 15, the second switch 14 is an NMOS transistor, the second voltage detection circuit 11 detects the voltage between the normally open contact K1-1 of the first relay 10 and the conversion circuit 1, the output end of the second voltage detection circuit 11 is electrically connected to the inverting input end of the second comparator 13, the non-inverting input end of the second comparator 13 receives a second preset signal for providing a second preset value, and when the output value of the second voltage detection circuit 11 is smaller than the second preset value, the second comparator 13 outputs a high level signal.

The output terminals of the second comparator 13 and the first comparator 8 are electrically connected to the input terminal of the first and circuit 12, the output terminal of the first and circuit 12 is electrically connected to the gate of the second switch device 14, the source of the second switch device 14 is grounded, the drain is connected to the power VCC through the coil K2 of the second relay 15, the normally open contact K2-1 of the second relay 15 is connected between the output terminal of the second backup power supply 6 and the input terminal of the inverter circuit 1, the normally closed contact K2-2 is electrically connected to the charging loop of the second backup power supply 6, the normally closed contact K2-3 is connected between the coil K1 of the first relay 10 and the drain of the first switch device 9, when the second comparator 13 outputs a high level signal and the first comparator 8 outputs a high level first execution signal, the first and circuit 12 outputs a high level second execution signal, and the second switch device 14 is turned on, the second relay 15 operates.

The voltage detection circuit further comprises a third voltage detection circuit 16 for detecting the voltage of the output end of the second standby power supply 6, a second and gate circuit 17, a third comparator 18 and a third execution module for connecting the energizing loop of the first relay 10, the third execution module comprises a third switch 19 and a third relay 20, the third switch 19 is an NMOS tube, the third voltage detection circuit 16 detects the voltage between the normally open contact K2-1 of the second relay 15 and the conversion circuit 1, the output end of the third voltage detection circuit 16 is electrically connected to the inverting input end of the third comparator 18, the non-inverting input end of the third comparator 18 receives a third preset signal for providing a third preset value, and when the output value of the third voltage detection circuit 16 is smaller than the third preset value, the second comparator 13 outputs a high level signal.

The output terminal of the third comparator 18 and the output terminal of the first and circuit 12 are electrically connected to the input terminal of the second and circuit 17, the output terminal of the second and circuit 17 is electrically connected to the gate of the third switch 19, the source of the third switch 19 is grounded, the drain is connected to the power VCC through the coil K3 of the third relay 20, the normally open contact K3-1 thereof is connected across the normally closed contact K2-3 of the second relay 15 and the first switch 9, when the second comparator outputs a high-level signal and the first and circuit 12 outputs a second execution signal of a high level, the second and circuit 17 outputs a third execution signal of a high level, the third switch 19 is turned on, and the third relay 20 operates.

The input module 3 comprises a magnetic reset circuit 21 connected with the primary side of the transformer 2 in parallel and a third MOS tube 24 of which the drain electrode is connected with the primary side of the transformer 2 in series; the output module 4 includes a first MOS transistor 22, a second MOS transistor 23, a fourth MOS transistor 25, a diode D1, a first auxiliary winding 26, a second auxiliary winding 27, a filter inductor L, and a filter capacitor C.

The first auxiliary winding 26 and the second auxiliary winding 27 are connected in series and coupled to the primary side of the transformer 2; the drain of the first MOS transistor 22 is coupled to the secondary side of the transformer 2, the gate thereof is coupled to one end of the second auxiliary winding 27, the gate of the fourth MOS transistor 25 and the cathode of the diode D1, and the source thereof is coupled to the source of the second MOS transistor 23, one end of the filter capacitor C, the source of the fourth MOS transistor 25 and the anode of the diode D1; the drain of the second MOS transistor 23 is coupled to the secondary side of the transformer 2 and the filter inductor L, respectively, and the gate thereof is coupled to the first auxiliary winding 26; the other end of the filter capacitor C is coupled with the filter inductor L; the drain of the fourth MOS transistor 25 is coupled to the first auxiliary winding 26 and the second auxiliary winding 27, respectively.

When the switching circuit works, when the voltage of the positive homonymous terminal of the auxiliary winding is higher than that of the negative homonymous terminal, the grid voltage of the fourth MOS tube 25 is higher than the source voltage, the source electrode is communicated with the drain electrode, the tap of the auxiliary winding is clamped to the ground by the fourth MOS tube 25, and the diode D1 is cut off reversely. The high voltage at the positive end of the auxiliary winding supplies power to the grid electrode of the first MOS tube 22, so that the source electrode and the drain electrode of the first MOS tube are conducted; the gate voltage of the second MOS transistor 23 is a negative voltage, and the source and drain thereof are turned off.

When the positive dotted terminal voltage of the auxiliary winding is lower than the negative dotted terminal, the source and the drain of the fourth MOS transistor 25 are cut off, the positive dotted terminal of the auxiliary winding is clamped to the ground by the diode D1, and the source and the drain of the first MOS transistor 22 are cut off; the negative dotted terminal of the auxiliary winding supplies power to the gate of the second MOS transistor 23, so that the source and the drain are conducted.

The above processes form a complete switching cycle, and the gate-source voltage of the second MOS transistor 23 is obtained by superimposing two sets of auxiliary winding voltages, thereby solving the problem of insufficient driving voltage of the second MOS transistor 23; the first auxiliary winding 26 and the second auxiliary winding 27 can be time-multiplexed, and the number of turns of the windings can be further reduced, so that the size of the windings is reduced.

The specific working process is as follows: when the voltage is reduced due to the open circuit at the front end of the converter circuit 1, the first comparator 8 outputs a first execution signal, and the first relay 10 operates to connect the power-on loop between the first backup power supply 5 and the converter circuit 1, so that the converter circuit 1 is supplied with electric energy, and the reliability of the operation of the device is improved.

When the electric quantity of the first standby power supply 5 is low, the first AND gate circuit 12 outputs a second execution signal, the second relay 15 acts to communicate with a power-on loop between the second standby power supply 6 and the conversion circuit 1 to supply electric energy to the conversion circuit 1, meanwhile, the first relay 10 resets, and the first standby power supply 5 is charged through the charging loop.

When the electric quantity of the second standby power supply 6 is low, the second AND gate circuit 17 outputs a third execution signal, the third relay 20 acts, the first relay 10 is powered on to act, a power-on loop between the first standby power supply 5 and the conversion circuit 1 is communicated, electric energy is provided for the conversion circuit 1, the second relay 15 resets, and the second standby power supply 6 is charged through a charging loop.

The embodiments of the present invention are preferred embodiments of the present invention, and the scope of the present invention is not limited by these embodiments, so: all equivalent changes made according to the structure, shape and principle of the invention are covered by the protection scope of the invention.

Claims

1. A DC-DC converter comprising a conversion circuit (1), the conversion circuit (1) comprising an input module (3) and an output module (4) coupled to each other by a transformer (2), characterized in that: the power supply control circuit also comprises a first standby power supply (5), a first voltage detection module used for detecting the voltage of the front end of the conversion circuit (1) and a first execution module used for controlling the connection and disconnection between the first standby power supply (5) and the conversion circuit (1) according to the output of the voltage detection module;

the power supply also comprises a second standby power supply (6), a second voltage detection module for detecting the voltage of the output end of the first standby power supply (5) and a second execution module for controlling the on-off between the second standby power supply (6) and the conversion circuit (1) according to the output of the second voltage detection module;

when the electric quantity of the first standby power supply (5) is low, a second standby power supply (6) is connected into the conversion circuit (1) and charges the first standby power supply (5); when the electric quantity of the second standby power supply (6) is low, the first standby power supply (5) is connected to the conversion circuit (1) and charges the second standby power supply (6);

the first voltage detection module comprises a first voltage detection circuit (7) and a first comparator (8), wherein the first voltage detection circuit is used for detecting the voltage of the front end of the conversion circuit (1), the first comparator (8) responds to the condition that the output value of the first voltage detection circuit (7) is smaller than a first preset value and sends a first execution signal to a first execution module, and the first execution module acts in response to the first execution signal;

the first execution module comprises a first switch part (9) and a first relay (10), the first switch part (9) is connected to an electrifying loop of the first relay (10) and is turned on in response to a first execution signal, and a normally open contact of the first relay (10) is connected between the first standby power supply (5) and the input end of the conversion circuit (1);

the second voltage detection module comprises a second voltage detection circuit (11) for detecting the voltage of the output end of the first standby power supply (5), a first AND gate circuit (12) and a second comparator (13), the second comparator (13) compares the output value of the second voltage detection circuit (11) with a second preset value, the first AND gate circuit (12) sends out a second execution signal in response to the fact that the output value of the second voltage detection circuit (11) is smaller than the second preset value and the first execution signal, and the second execution module acts in response to the second execution signal;

the second execution module comprises a second switch piece (14) and a second relay (15), the second switch piece (14) is connected to an electrifying loop of the second relay (15) and is turned on in response to a second execution signal, a normally open contact of the second relay (15) is connected between the second standby power supply (6) and the input end of the conversion circuit (1), and a normally closed contact of the second relay (15) is connected between the first relay (10) and the first switch piece (9).

2. A DC-DC converter according to claim 1, wherein: one normally closed contact of the first relay (10) is connected to a charging circuit of the first standby power supply (5), and one normally closed contact of the second relay (15) is connected to a charging circuit of the second standby power supply (6).

3. A DC-DC converter according to claim 2, wherein: the power supply further comprises a third voltage detection circuit (16) used for detecting the voltage of the output end of the second standby power supply (6), a second AND gate circuit (17), a third comparator (18) and a third execution module used for switching on the power-on loop of the first relay (10), wherein the third comparator (18) compares the output value of the third voltage detection circuit (16) with a third preset value, the second AND gate circuit (17) outputs a third execution signal in response to the fact that the output value of the third voltage detection circuit (16) is smaller than the third preset value and the second execution signal, and the third execution module acts in response to the third execution signal.

4. A DC-DC converter according to claim 3, wherein: the third execution module comprises a third switch piece (19) and a third relay (20), the third switch piece (19) is connected to the electrifying loop of the third relay (20) and is conducted in response to a third execution signal, and a normally open contact of the third relay (20) is connected to the normally closed contact of the first switch piece (9) in a mode of being bridged between the first switch piece (9) and the second relay (15).