CN110497796A - A low-voltage power supply system and control method for a new energy vehicle - Google Patents

Abstract

Present invention discloses a kind of low-voltage power supply systems of new-energy automobile, newly energy automobile is equipped with the battery pack as power source, described battery pack the two poles of the earth connect battery management system, the battery management system is equipped with the trickle charge interface of connection charger and the fast charge interface of connection direct current charge equipment, the input terminal of the two poles of the earth connection DCDC of the battery pack, the low-voltage output of the DCDC is directly connected to vehicle-mounted electricity consumption device, DCDC fuse and DCDC relay are in series between the anode and DCDC of the battery pack, the input end loop of the relay control interface connection DCDC relay of the battery management system.The system not only solves low-voltage power supply, reduces integral vehicle cost, and prevent battery pack during DCDC constantly powers again, solves the problems, such as battery pack low battery and battery over-discharge.

Description

A low-voltage power supply system and control method for a new energy vehicle

technical field

The invention relates to the field of new energy vehicles.

Background technique

At present, whether the new energy vehicle is an electric vehicle or a hybrid vehicle without wheels, the power supply of the low-voltage electrical appliance controller is 12V/24V, and the power supply scheme is used to charge the vehicle battery after the high-voltage battery pack is transformed by DCDC (high-voltage direct current to low-voltage direct current). . The on-board battery supplies power to low-voltage electrical equipment.

Because traditional fuel vehicles do not have high-voltage battery packs, the electrical equipment of the vehicle must use the engine to drive a small motor to generate electricity to charge the battery. Moreover, when starting a traditional fuel vehicle, the starter needs to drive the internal combustion engine to start, so a large peak power is required. Therefore, a low-voltage battery is required to store electricity.

At present, battery vehicles are transitioned from traditional fuel vehicles, and the low-voltage battery power supply method of traditional vehicles is still used. However, the battery low-voltage power supply method has the following disadvantages.

1. The cost of the battery is relatively high, which increases the cost of the vehicle.

2. The quality of the battery is heavy, because the curb quality of the vehicle has a great relationship with the fuel consumption and power consumption of the vehicle, which is not conducive to the lightweight of the vehicle.

3. The battery is large in size and takes up a lot of space in the vehicle, which is not conducive to the layout of the power system.

4. The whole vehicle is powered by a battery. The battery is generally a lead battery, which has a short lifespan and is easily damaged by over-discharge if it is not charged for a long time.

In view of the above problems, DCDC can be used to replace the battery power supply. DCDC takes the high-voltage power of the battery pack and converts it into low-voltage power to supply power for the whole vehicle. However, directly taking the high-voltage power of the battery pack will easily cause the SOC of the battery pack to be too low, and long-term storage of the vehicle will easily cause The ground of the battery pack is damaged.

Contents of the invention

The technical problem to be solved by the present invention is to realize a low-voltage power supply system for a battery pack and a whole vehicle that uses DCDC instead of a storage battery for power supply and can prevent over-discharge.

In order to achieve the above object, the technical solution adopted by the present invention is: a low-voltage power supply system for a new energy vehicle, the new energy vehicle is equipped with a battery pack as a power source, the two poles of the battery pack are connected to a battery management system, and the battery management system There is a slow charging interface connected to a charger and a fast charging interface connected to a DC fast charging device. The two poles of the battery pack are connected to the input end of the DCDC, and the low voltage output end of the DCDC is directly connected to the vehicle-mounted electrical device. A DCDC fuse and a DCDC relay are connected in series between the positive pole of the battery and the DCDC, and the relay control interface of the battery management system is connected to the input end circuit of the DCDC relay.

The positive pole of the battery pack is connected to the positive high-voltage output line, and the negative pole is connected to the negative high-voltage output line. A positive fuse and a positive relay are connected in series on the positive high-voltage output line. A negative relay is connected in series to the negative high-voltage output line. The positive The high-voltage output line and the negative high-voltage output line are connected to the power output interface of the high-voltage battery pack.

A battery pack, a negative relay, a positive fuse, a positive relay, a DCDC fuse, a DCDC relay, and a DCDC are fixed in the casing of the high-voltage battery pack.

The relay control interface of the battery management system is connected to the input end circuits of the negative relay and the positive relay.

The new energy vehicles include pure electric vehicles, hybrid vehicles, and vinyl vehicles.

A control method based on the low-voltage power supply system of the new energy vehicle:

1) The battery management system controls the DCDC relay to be normally closed;

2) When the battery management system is working, obtain the status information of the battery pack in real time;

3) When the acquired state information of the battery pack reaches the preset condition of disconnecting the DCDC relay, the battery management system disconnects the DCDC relay.

In the above 3), if the whole vehicle is in the driving state, the DCDC relay is cut off with a delay, and an alarm is given through the car audio.

In the above 3), the voice of the alarm includes playing the cause of the failure, about to cut off the power supply of the vehicle-mounted electrical device, and playing the countdown to the upcoming cut-off action in the final stage of the delay.

When the vehicle is not running for more than the set time, the battery management system cuts off the DCDC relay, and when the battery management system receives the charging signal, it restores the DCDC relay to the state of the circuit.

The state information of the battery pack includes discharge capacity information, power SOC information, and fault information, and the condition for disconnecting the DCDC relay is that the discharge capacity is lower than a set value, the power SOC is lower than a set value, and/or a preset fault occurs type.

The advantages of the present invention are:

1. The battery is canceled, the quality of the curb is reduced, and the battery life of the vehicle is improved;

2. The cost of the whole vehicle is reduced, which is beneficial to the automobile manufacturer to reduce the cost of the whole vehicle;

3. Reduce the layout of batteries in the whole vehicle. Conducive to power system layout;

4. It can intelligently identify that the SOC of the battery pack is too low, and automatically protect the battery pack from being over-discharged;

5. After the vehicle is powered off, the DCDC can be activated by slow charging or fast charging, so that it can continue to work;

6. Prevent the high voltage of the battery pack from being drawn out of the battery pack.

Description of drawings

The following is a brief description of the content expressed in each drawing in the description of the present invention and the marks in the figure:

Figure 1 is a schematic diagram of a low-voltage power supply system for a new energy vehicle;

The marks in the above figures are: 1. High voltage battery pack; 2. Battery management system; 3. Slow charging interface; 4. Charger; 5. Charging gun; 6. DC fast charging; 7. Battery pack; 8. Negative Class relay; 9. Positive class fuse; 10. Positive class relay; 11. DCDC fuse; 12. DCDC relay; 13. DCDC.

Detailed ways

Referring to the accompanying drawings, through the description of the embodiments, the specific embodiments of the present invention include the shape, structure, mutual position and connection relationship of each part, the function and working principle of each part, and the manufacturing process of the various components involved. And the method of operation and use, etc., are described in further detail to help those skilled in the art have a more complete, accurate and in-depth understanding of the inventive concepts and technical solutions of the present invention.

As shown in Figure 1, the low-voltage power supply system of new energy vehicles includes high-voltage battery pack 1, battery management system 2 (BMS), charger 4, charging gun 5, DC fast charging 6, battery pack 7, negative relay 8, positive pole Fuse 9, positive relay 10, DCDC fuse 11, DCDC relay 12, DCDC13 (high voltage DC to low voltage DC).

A battery pack 7 , a negative relay 8 , a positive fuse 9 , a positive relay 10 , a DCDC fuse 11 , a DCDC relay 12 , and a DCDC13 are fixed in the casing of the high-voltage battery pack.

The battery management system BMS2 mainly manages the battery pack, including the management of the battery pack charge and discharge capacity, battery voltage, current power, battery SOC/HOC and other system indicators.

When the high-voltage battery pack 1 leaves the factory, the battery pack does not output high-voltage power and low-voltage electrical appliances. After the car is produced and assembled with a battery pack, a DC fast charging gun or an AC slow charging gun can be inserted, and the slow charging charger 4 or DC fast charging 6 will output low-voltage power supply for the battery management system 2 to supply power. The battery management system thus engages the DCDC relay 12 , thereby starting the DCDC 13 to supply power to the external electrical appliances and the battery management system 2 . The whole vehicle starts to start normal function operation, and the pull-in work of the positive relay 10 or the negative relay 8 can be carried out according to the demand of the whole vehicle.

The battery pack 1 starts to work synchronously with the battery management system 2 after the DCDC 13 is activated by the slow charging charger 4 or the DC fast charging 6 , and the DCDC relay 12 is always in the pull-in state, thereby outputting low-voltage direct current to the outside. At the same time, the battery management system 2 detects the discharge capacity/power SOC/fault of the battery pack. When the battery management system 2 detects that the power SOC is low, the discharge capacity is insufficient, and there are serious faults and other factors. If the whole vehicle is not in the running state, the battery management system 2 cuts off the DCDC relay 12 and stops outputting low-voltage electricity. If the whole vehicle is in a driving state, the battery management system 2 requests the whole vehicle to drive to a safe area for delayed power-off.

When the new energy vehicle is placed outside the non-driving state for a long time, the system can detect factors such as battery power through the battery management system 2 to prevent the battery pack 7 from being overcharged by continuous discharge when the DCDC 13 is always working. damage the battery. When the DCDC13 stops working, only the charging activation process needs to be performed.

The positive relay 10 can be controlled by the battery management system 2, or can be controlled by other controllers according to the needs of the whole vehicle; the positive relay 10 may be placed inside the battery pack or outside the battery pack according to the whole vehicle plan.

The negative relay 8 can be controlled by the battery management system 2, or can be controlled by other controllers according to the needs of the whole vehicle. The negative relay 8 can be placed inside the battery pack or outside the battery pack according to the vehicle scheme.

The positive fuse 9 can be placed inside the battery pack or outside the battery pack according to the whole vehicle plan, or it can be canceled. The positive fuse 9 is only used for protection against short circuit and overload, and can be canceled according to requirements.

The DCDC fuse 11, DC relay 12, and DCDC13 can be placed inside the battery pack or elsewhere in the vehicle according to the vehicle solution. DC Quick Charge 6 meets the national standard for electric power fast charging, and the voltage range of the low-voltage controller is within the range of 6-50V.

The present invention has been exemplarily described above in conjunction with the accompanying drawings. Obviously, the specific implementation of the present invention is not limited by the above methods, as long as various insubstantial improvements are adopted in the method concept and technical solutions of the present invention, or there is no improvement Directly applying the conception and technical solutions of the present invention to other occasions falls within the protection scope of the present invention.

Claims (9)

1. A low-voltage power supply system for a new energy vehicle. The new energy vehicle is provided with a battery pack as a power source, and the two poles of the battery pack are connected to a battery management system. The fast charging interface of the DC fast charging device is characterized in that: the two poles of the battery pack are connected to the input terminals of the DCDC, the low-voltage output terminals of the DCDC are directly connected to the vehicle-mounted electrical devices, and the positive pole of the battery pack and the DCDC are connected to each other. A DCDC fuse and a DCDC relay are connected in series, and the relay control interface of the battery management system is connected to the input end circuit of the DCDC relay. 2. The low-voltage power supply system for new energy vehicles according to claim 1, characterized in that: the positive pole of the battery pack is connected to the positive high-voltage output line, the negative pole is connected to the negative high-voltage output line, and a positive pole is connected in series on the positive high-voltage output line A fuse and a positive relay, the negative high-voltage output line is connected in series with a negative relay, and the positive high-voltage output line and the negative high-voltage output line are connected to the output interface of the high-voltage battery pack power supply. 3. The low-voltage power supply system for new energy vehicles according to claim 2, characterized in that: a battery pack, a negative relay, a positive fuse, a positive relay, a DCDC fuse, DCDC relay, DCDC. 4. The low-voltage power supply system for new energy vehicles according to claim 2 or 3, characterized in that: the relay control interface of the battery management system is connected to the input circuit of the negative relay and the positive relay. 5. The low-voltage power supply system for new energy vehicles according to claim 4, characterized in that: said new energy vehicles include pure electric vehicles, hybrid vehicles, vinyl vehicles. 6. The control method based on the low-voltage power supply system of the new energy vehicle described in any one of claims 1-5, characterized in that: 1) The battery management system controls the DCDC relay to be normally closed; 2) When the battery management system is working, obtain the status information of the battery pack in real time; 3) When the acquired state information of the battery pack reaches the preset condition of disconnecting the DCDC relay, the battery management system disconnects the DCDC relay. In the above 3), if the whole vehicle is in the driving state, the DCDC relay is cut off with a delay, and an alarm is given through the car audio. 7. The control method according to claim 6, characterized in that: in said 3), the voice of the alarm includes playing the cause of the failure, about to cut off the power supply of the vehicle-mounted electrical device, and in the final stage of the delay to the upcoming Cut off the action for a countdown playback. 8. The control method according to claim 7, wherein the battery management system cuts off the DCDC relay when the vehicle is not running for more than the set time, and restores the DCDC relay to the state of the DCDC relay when the battery management system receives the charging signal . 9. The control method according to claim 6, 7 or 8, wherein the state information of the battery pack includes discharge capacity information, power SOC information, and fault information, and the condition for disconnecting the DCDC relay is that the discharge capacity is low is lower than the set value, the power SOC is lower than the set value, and/or a preset fault type occurs.