CN210183226U

CN210183226U - DC-DC converter and hydrogen fuel cell

Info

Publication number: CN210183226U
Application number: CN201921485009.0U
Authority: CN
Inventors: Shangchen Du; 杜尚琛; Weiguang Sun; 孙维广; Peng Qiao; 乔鹏; Lei Chen; 陈磊; Guangzhi Zhang; 张广志; Dali Shen; 申大力
Original assignee: Invt Powre Electronics (suzhou) Co Ltd
Current assignee: Invt Powre Electronics (suzhou) Co Ltd
Priority date: 2019-09-06
Filing date: 2019-09-06
Publication date: 2020-03-24
Anticipated expiration: 2029-09-06

Abstract

The utility model discloses a DC-DC converter, include: the Boost circuit is used for boosting voltage, the Boost circuit is connected with a positive bus and a negative bus, the input end of the Boost circuit forms a low-voltage side, the output end of the Boost circuit forms a high-voltage side, and an energy storage filter capacitor in the Boost circuit is connected between the positive bus and the negative bus; and the power-on buffer circuit is connected to the positive bus, is positioned between the energy storage filter capacitor and the output end, and is used for charging the energy storage filter capacitor when the high-voltage side is powered on. The utility model discloses be applied to in the new energy automobile, through implementing the embodiment of the utility model provides a, can improve the reliability, promote the security, reduce volume, reduce cost. In addition the utility model also discloses a hydrogen fuel cell, including in the hydrogen fuel cell the DC-DC converter.

Description

DC-DC converter and hydrogen fuel cell

Technical Field

The utility model relates to a new energy automobile field especially relates to a DC-DC converter and hydrogen fuel cell.

Background

The DC-DC converter is a key component in a hydrogen fuel cell power system to achieve energy conversion. The hydrogen fuel cell directly converts hydrogen fuel stored in the cell into electric energy through chemical reaction, and has the advantages of high energy conversion efficiency, no noise, no pollution, rich fuel sources and the like. However, the fuel cell has a disadvantage of soft output characteristics; some disturbances occurring during the operation of the fuel cell may cause the output voltage of the fuel cell stack to fluctuate, thereby affecting the bus voltage to fluctuate by a certain amount. The motor of the electric automobile is a very large dynamic load, and if no disturbance resisting device is arranged between the bus and the electrical appliance, the working voltage of the electrical appliance on the fuel cell automobile can be in an overvoltage or low-voltage state. The long-time operation can influence the life-span of being equipped with on-vehicle electrical apparatus. Therefore, the fuel cell is generally connected with the motor load through a DC-DC converter, and the equipped DC-DC converter is required to have better anti-interference performance, the output voltage can be quickly restored to balance when the load suddenly changes, and the characteristics of high power, small volume, good heat dissipation and the like are met. The decoupling between the fuel cell and the high voltage of the whole vehicle is realized by accurately controlling the output power of the engine, and the power distribution and the optimized control between the power systems of the whole vehicle are realized; the working state of the engine is stabilized, and the service life of the engine is prolonged.

At present, with the change of new energy subsidy policy in China, the output power of a hydrogen fuel automobile is becoming higher and higher, and the output power can reach dozens or even hundreds of kilowatts. In addition, the endurance mileage of the hydrogen fuel automobile is greatly influenced by the specific energy of the whole automobile. In order to improve the power density ratio of the whole vehicle, a non-isolated topology is generally adopted in a high-power DC-DC converter to realize smaller volume and heat dissipation. When the DC-DC converter works, the high-voltage side is firstly electrified, and because the BOOST topological output end has an energy storage filter capacitor with larger capacity, an electrifying buffer circuit is required to be added into a main loop of the DC-DC converter to limit the impact current, and a module and a bus capacitor are protected. As shown in fig. 1, fig. 1 is a power-up buffering scheme that is common at present. The high-voltage side output prevents current from flowing backwards when the high-voltage side is electrified by serially connecting a high-power diode so as to protect the bus capacitor; the low-voltage side input adopts a relay series resistor to be connected with a high-power contactor in parallel to realize power-on buffering. However, as the power of the DC-DC converter is continuously enlarged, the input current of the low-voltage end becomes larger and larger; the power selection and the cost of the contactor at the low-voltage end are higher and higher, so that the device selection is difficult; and the loss caused by the heat generation of the device increases correspondingly with the increase of the power, and a series of problems of increasing the volume and weight of the DC-DC converter are caused.

SUMMERY OF THE UTILITY MODEL

The utility model provides a DC-DC converter and hydrogen fuel cell aims at solving the technical problem that DC-DC converter reliability is low among the correlation technique.

The utility model provides a DC-DC converter, it includes: the Boost circuit is used for boosting voltage, the Boost circuit is connected with a positive bus and a negative bus, the input end of the Boost circuit forms a low-voltage side, the output end of the Boost circuit forms a high-voltage side, and an energy storage filter capacitor in the Boost circuit is connected between the positive bus and the negative bus; and the power-on buffer circuit is connected to the positive bus, is positioned between the energy storage filter capacitor and the output end, and is used for charging the energy storage filter capacitor when the high-voltage side is powered on.

Further, the power-up buffer circuit includes: and the backward flow unit is used for preventing current from backward flowing when the high-voltage side is electrified, is connected to the positive bus and is positioned between the energy storage filter capacitor and the output end. And the buffer unit is used for limiting impact current when the high-voltage side is electrified and is connected with the backflow unit in parallel.

Furthermore, the backward flow unit comprises a second power diode, the anode of the second power diode is connected with the energy storage filter capacitor, and the cathode of the second power diode is connected with the output end.

Further, the buffer unit comprises a first resistor, and the first resistor is connected with the backflow unit in parallel.

Furthermore, the buffer unit further comprises a switch device, and the switch device is connected in series with the first resistor and is used for controlling the on-off of the buffer unit.

Further, the switching device is a relay.

Furthermore, the power-on buffer circuit comprises a first resistor, a second power diode and a relay, wherein the anode of the second power diode is connected with the energy storage filter capacitor, the cathode of the second power diode is connected with the output end, and the relay is connected with the first resistor in series and then connected with the second power diode in parallel.

Further, still include: and the voltage detection circuit is connected between the positive bus and the negative bus and is used for detecting the voltage at two ends of the filtering energy storage capacitor so as to enable the DC-DC converter to work.

Further, still include: and the current detection circuit is connected with the output end and is used for adjusting the output current.

The utility model also provides a hydrogen fuel cell, it includes: and a DC-DC converter, wherein the DC-DC converter is the DC-DC converter.

Compared with the prior art, the beneficial effects of the utility model are that: the utility model discloses a to go up electric buffer circuit and set up the output at the high-pressure side, charge for energy storage filter capacitor when going up electricity in the high-pressure side, restricted impulse current simultaneously, can improve the reliability, promote the security.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required 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 some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without any creative effort.

FIG. 1 is a circuit schematic of a prior art power-on buffering scheme for a DC-DC converter;

fig. 2 is a schematic circuit block diagram of the DC-DC converter of the present invention; and

fig. 3 is a schematic circuit diagram of the DC-DC converter according to the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, not all, of the embodiments of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative work belong to the protection scope of the present invention.

It will be understood that the terms "comprises" and/or "comprising," when used in this specification and the appended 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.

It is also to be understood that the terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used in the specification and the appended claims, the singular forms "a", "an", and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.

It should be further understood that the term "and/or" as used in the specification and the appended claims refers to any and all possible combinations of one or more of the associated listed items, and includes such combinations.

Referring to fig. 2-3, an embodiment of a DC-DC converter 100 provided by the present invention is shown. The DC-DC converter 100 is smaller and smaller, and the cost and reliability are higher and higher. The utility model provides a DC-DC converter 100, through the technical scheme who goes up electric snubber circuit 20 on the output adoption at DC-DC converter 100 high-pressure side, not only reduce whole DC-DC converter 100's volume, improve production efficiency, the maintenance warranty in the later stage of being convenient for moreover saves the cost, also makes entire system's reliability obtain very big improvement. The utility model discloses use in new energy automobile, the embodiment of the utility model provides a DC-DC converter 100 includes: a Boost circuit 10 and a power-up buffer circuit 20. The Boost circuit 10 is used for boosting voltage, the Boost circuit 10 is connected with a positive bus and a negative bus, the input end of the Boost circuit 10 forms a low-voltage side, the output end of the Boost circuit 10 forms a high-voltage side, and an energy storage filter capacitor C1 in the Boost circuit 10 is connected between the positive bus and the negative bus. The power-on buffer circuit 20 is connected to the positive bus and located between the energy storage filter capacitor C1 and the output terminal, and the power-on buffer circuit 20 is configured to charge the energy storage filter capacitor C1 when the high-voltage side is powered on. Through the design, the power-on buffer circuit 20 is arranged at the output end of the high-voltage side, namely the rear end of the energy storage filter capacitor C1, and the energy storage filter capacitor C1 is charged when the high-voltage side is powered on, so that the impact current is limited, the reliability can be improved, and the safety can be improved.

In one embodiment, the power-up buffer circuit 20 includes: the reverse flow unit 21 is used for preventing current from flowing backwards when the high-voltage side is powered on, and the reverse flow unit 21 is connected to the positive bus and located between the energy storage filter capacitor C1 and the output end. The buffer unit 22 is used for limiting the impact current when the high-voltage side is powered on, and the buffer unit 22 is connected with the backflow unit 21 in parallel. Through the design, because the high-voltage side is firstly electrified when the DC-DC converter 100 works, when the high-voltage side is electrified, the buffer unit 22 is used for charging the energy storage filter capacitor C1 and limiting the impact current, and the backflow unit 21 is used for preventing the current from flowing backwards to protect other devices when the energy storage filter capacitor C1 is charged, so that the reliability is improved, and the safety is improved.

In an embodiment, the backward flow unit 21 includes a second power diode D2, an anode of the second power diode D2 is connected to the energy storage filter capacitor C1, and a cathode of the second power diode D2 is connected to the output terminal. When the high-voltage side is powered on, the second power diode D2 is turned off, so that current flows through the buffer unit 22 to charge the energy storage filter capacitor C1. By adopting the second power diode D2 as the backward flow unit 21, compared with the existing scheme, the direct current contactor of the low-voltage side main loop current is omitted, the reliability is improved, the cost is greatly saved, and the volume and the weight are reduced.

In an embodiment, the buffer unit 22 includes a first resistor R1, and the first resistor R1 is connected in parallel with the backflow unit 21. When the high-voltage side is powered on, the backward flow unit 21 is turned off to enable current to charge the energy storage filter capacitor C1 through the first resistor R1, and the first resistor R1 provides buffering to limit the impact current at the moment of powering on the high-voltage side. The use of the first resistor R1 as the buffer unit 22 provides a significant cost savings.

In an embodiment, the buffer unit 22 further includes a switching device, which is connected in series with the first resistor R1, and is used for controlling on/off of the buffer unit 22. When the high-voltage side is powered on, the switching device is closed so that current flows through the buffer unit 22 to charge the energy storage filter capacitor C1. When the DC-DC converter 100 is in the working state, the switching device is turned off to ensure that the current does not pass through the first resistor R1, and the first resistor R1 is prevented from heating and seriously damaging the device.

In one embodiment, the switching device is relay RLY1, although it is understood that other switching devices are possible.

In an embodiment, the Boost circuit 10 includes an inductor L1, a first diode D1, an IGBT, and a storage filter capacitor C1, the inductor L1 is connected in series to a positive bus and is located at an input end of a low voltage side, a positive electrode of the first diode D1 is connected to the inductor L1, a negative electrode of the first diode D1 is connected to the upper buffer circuit 20, the IGBT is connected between the positive bus and the negative bus, the IGBT is located between the inductor L1 and the first diode D1, the storage filter capacitor C1 is connected between the positive bus and the negative bus, and the storage filter capacitor C1 is located between the first diode D1 and the upper buffer circuit 20. It is of course understood that the Boost circuit 10 may also have other forms of topologies.

In an embodiment, the DC-DC converter 100 further includes a voltage detection circuit 30 and a current detection circuit 40, the voltage detection circuit 30 is connected between the positive bus and the negative bus, and the voltage detection circuit 30 is configured to detect a voltage across the filtering energy storage capacitor C1 to enable the DC-DC converter 100 to operate. The current detection circuit 40 is connected to the output terminal, and the current detection circuit 40 is used for adjusting the output current. When the high-voltage side is powered on, the energy storage filter capacitor C1 is charged through the power-on buffer circuit 20, the voltage detection circuit 30 detects the capacitance at the two ends of the energy storage filter capacitor C1, and when the capacitance at the two ends of the energy storage filter capacitor C1 reaches a threshold value, the DC-DC converter 100 is enabled to operate. And when the buffer unit 22 or the backward flow unit 21 is damaged and cannot work, the voltage detection circuit 30 may detect that the voltage at the two ends of the energy storage filter capacitor C1 does not reach the output voltage, so that the DC-DC converter 100 cannot operate, and may still play a role in protecting the DC-DC converter 100. In addition, when the DC-DC converter 100 works, the duty ratio of the IGBT is controlled to adjust the output voltage of the Boost circuit 10, and the voltage detection circuit 30 and the current detection circuit 40 perform a closed-loop feedback control function to adjust the output voltage and the output current when the DC-DC converter works in a high-frequency switching state.

In another embodiment, the power-on buffer circuit 20 includes a first resistor R1, a second power diode D2, and a relay RLY1, wherein an anode of the second power diode D2 is connected to the energy storage filter capacitor C1, a cathode of the second power diode D2 is connected to the output terminal, and the relay RLY1 is connected in series with the first resistor R1 and then connected in parallel with the second power diode D2. Through the design, the power-on buffer circuit 20 is arranged at the output end of the high-voltage side, namely the rear end of the energy storage filter capacitor C1, and the energy storage filter capacitor C1 is charged when the high-voltage side is powered on, so that the impact current is limited, the reliability can be improved, the safety can be improved, the size can be reduced, and the cost can be reduced.

The embodiment of the utility model provides a show a DC-DC converter 100, through to go up electric buffer circuit 20 and set up the output at the high-pressure side, for energy storage filter capacitor C1 charges when going up the electricity in the high-pressure side, restricted impulse current simultaneously, can improve the reliability, promote the security, reduce volume, reduce cost.

In another embodiment, the present invention provides a hydrogen fuel cell, which includes the DC-DC converter 100 of the above embodiment, and the DC-DC converter 100 can improve reliability, improve safety, reduce volume, and reduce cost.

The above description is only for the specific embodiments of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily think of various equivalent modifications or replacements within the technical scope of the present invention, and these modifications or replacements should be covered within the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. A DC-DC converter, comprising:

the Boost circuit is used for boosting voltage, the Boost circuit is connected with a positive bus and a negative bus, the input end of the Boost circuit forms a low-voltage side, the output end of the Boost circuit forms a high-voltage side, and an energy storage filter capacitor in the Boost circuit is connected between the positive bus and the negative bus;

and the power-on buffer circuit is connected to the positive bus, is positioned between the energy storage filter capacitor and the output end, and is used for charging the energy storage filter capacitor when the high-voltage side is powered on.

2. The DC-DC converter of claim 1, wherein the power-up snubber circuit comprises:

a backward flow unit for preventing current from backward flowing when the high voltage side is powered on, the backward flow unit is connected to the positive bus and is positioned between the energy storage filter capacitor and the output end,

and the buffer unit is used for limiting impact current when the high-voltage side is electrified and is connected with the backflow unit in parallel.

3. The DC-DC converter according to claim 2, wherein the backward flow unit comprises a second power diode, an anode of the second power diode is connected with the energy storage filter capacitor, and a cathode of the second power diode is connected with the output terminal.

4. The DC-DC converter of claim 2, wherein the snubber unit includes a first resistor connected in parallel with the back-flow unit.

5. The DC-DC converter according to claim 4, wherein the snubber unit further comprises a switching device connected in series with the first resistor for controlling the switching of the snubber unit.

6. The DC-DC converter according to claim 5, wherein the switching device is a relay.

7. The DC-DC converter of claim 1, wherein the power-up snubber circuit comprises a first resistor, a second power diode, and a relay, wherein an anode of the second power diode is connected to the energy storage filter capacitor, a cathode of the second power diode is connected to the output terminal, and the relay is connected in series with the first resistor and then connected in parallel with the second power diode.

8. The DC-DC converter according to any one of claims 1 to 7, further comprising:

and the voltage detection circuit is connected between the positive bus and the negative bus and is used for detecting the voltage at two ends of the filtering energy storage capacitor so as to enable the DC-DC converter to work.

9. The DC-DC converter of claim 8, further comprising:

and the current detection circuit is connected with the output end and is used for adjusting the output current.

10. A hydrogen fuel cell, characterized by comprising: a DC-DC converter according to any one of claims 1 to 9.